Russell A Chipman

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Journals/Publications

• Banerjee, S., Chipman, R., & Otani, Y. (2020). Simultaneous balancing of geometric transformation and linear polarizations using six-fold-mirror geometry over the visible region. Opt. Lett., 45(9), 2510--2513.
• Banerjee, S., Chipman, R., Hagen, N., & Otani, Y. (2020). Broadband achromatic tunable polarization rotator. Optics Communications, 454, 124456.
• Banerjee, S., Chipman, R., Hagen, N., & Otani, Y. (2020). Native oxide layer effect on polarization cancellation for mirrors over the visible to near-infrared region. Advanced Optical Technologies, 9(4), 175--181.
• Hart, K. A., Kupinski, M. K., Wu, D. L., & Chipman, R. A. (2020). First results from an uncooled LWIR polarimeter for cubesat deployment. Optical Engineering, 59(7), 1 -- 17.
• Li, L. W., Kupinski, M., Brown, M., & Chipman, R. (2020). Comparing Classification Performance of Mueller Matrix Parameters for Diffuse Materials. Electronic Imaging, 2020(14), 263-1-263-7.
• Bradley, C. L., Diner, D. J., Xu, F., Kupinski, M., & Chipman, R. A. (2019). Spectral Invariance Hypothesis Study of Polarized Reflectance With the Ground-Based Multiangle SpectroPolarimetric Imager. IEEE Transactions on Geoscience and Remote Sensing, 57(10), 8191-8207.
• Kupinski, M. K., Bradley, C. L., Diner, D. J., Xu, F., & Chipman, R. A. (2019). Angle of linear polarization images of outdoor scenes. Optical Engineering, 58(8), 1-12.
• López-Téllez, J. M., Chipman, R. A., Li, L. W., McEldowney, S. C., & Smith, M. H. (2019). Broadband extended source imaging Mueller-matrix polarimeter. Opt. Lett., 44(7), 1544-1547.
• Diner, D. J., Boland, S. W., , M., , C., Burke, K. A., , R., Di, L., Garay, M. J., , S., , E., , M., , V., Kalashnikova, O. V., , Y., Lyapustin, A. I., Martin, R. V., , A., Ostro, B. D., , B., , , J., et al. (2018). Advances in multiangle satellite remote sensing of speciated airborne particulate matter and association with adverse health effects: from MISR to MAIA. Journal of Applied Remote Sensing, 12(4), 1-23.
• Harten, G. v., Diner, D. J., Daugherty, B., Rheingans, B. E., Bull, M. A., Seidel, F. C., Chipman, R. A., Cairns, B., Wasilewski, A. P., & Knobelspiesse, K. D. (2018). Calibration and validation of Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) polarization measurements. Appl. Opt., 57(16), 4499-4513.
• Breckinridge, J. B., & Chipman, R. A. (2016). Telescope polarization and image quality: Lyot coronagraph performance. Proc. SPIE, 9904, 99041C-99041C-16.
• Jota, T. S., & Chipman, R. A. (2016). Polarization aberrations induced by graded multilayer coatings in EUV lithography scanners. Proc. SPIE, 9776, 977617-977617-14.
• Kupinski, M., & Chipman, R. (2016). Power spectra trends in imaging polarimetry of outdoor solar illuminated scenes. Proc. SPIE, 9853, 98530P-98530P-5.
• Bradley, C. L., Kupinski, M., Diner, D. J., Xu, F., & Chipman, R. A. (2015). Spectral invariance hypothesis study of polarized reflectance with Ground-based Multiangle SpectroPolarimetric Imager (GroundMSPI). Proc. SPIE, 9613, 96130U-96130U-9.
• Chipman, R. A. (2015). Polarimeter calibration error gets far out of control. Proc. SPIE, 9583, 95830H-95830H-6.
• Chipman, R. A., & Lam, W. (2015). The Polaris-M ray tracing program. Proc. SPIE, 9613, 96130J-96130J-18.
• Chipman, R. A., & Lam, W. (2015). The point spread function in paraxial optics. Proc. SPIE, 9578, 957803-957803-10.
• Chipman, R. A., Lam, W., & Breckinridge, J. (2015). Polarization aberration in astronomical telescopes. Proc. SPIE, 9613, 96130H-96130H-11.
• Chipman, R. A., Lam, W., & Onishi, M. (2015). Why diffractive retarders are not in common use. Proc. SPIE, 9613, 96130L-96130L-4.
• Hsu, W., Davis, J., Chipman, R., & Pau, S. (2015). Compound dichroic polarizers with wavelength-dependent transmission axes. Appl. Opt., 54(21), 6476--6481.
• Keresztes, J. C., Koshel, R. J., Chipman, R., Stover, J. C., & Saeys, W. (2015). A cross-polarized freeform illumination design for glare reduction in fruit quality inspection. Proc. SPIE, 9629, 962904-962904-15.
• Kupinski, M., Bradley, C., Diner, D., Xu, F., & Chipman, R. (2015). Applying a microfacet model to polarized light scattering measurements of the Earth's surface. Proc. SPIE, 9613, 96130T-96130T-11.
• LaCasse, C. F., Rodr\'iguez-Herrera, O. G., Chipman, R. A., & Tyo, J. S. (2015). Spectral density response functions for modulated polarimeters. Appl. Opt., 54(32), 9490--9499.
• Lam, W., & Chipman, R. (2015). Balancing polarization aberrations in crossed fold mirrors. Appl. Opt., 54(11), 3236--3245.
• Kupinski, M. K., Chipman, R. A., & Clarkson, E. (2014). Relating the statistics of the angle of linear polarization to measurement uncertainty. Optical Engineering, 53(11), 113108--113108.
• Chipman, R., & Peinado, A. (2013). The mystery of the birefringent butterfly. Optics and Photonics News, 24(10), 52-57.
• Diner, D. J., Garay, M. J., Kalashnikova, O. V., Rheingans, B. E., Geier, S., Bull, M. A., Jovanovic, V. M., Feng, X. u., Bruegge, C. J., Davis, A., Crabtree, K., & Chipman, R. A. (2013). Airborne multiangle spectro polarimetric imager (AirMSPI) observations over California during NASA's Polarimeter Definition Experiment (PODEX). Proceedings of SPIE - The International Society for Optical Engineering, 8873.
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  Abstract: The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) is an ultraviolet/visible/near-infrared pushbroom camera mounted on a single-axis gimbal to acquire multiangle imagery over a ±67° along-track range. The instrument flies aboard NASA's high-altitude ER-2 aircraft, and acquires Earth imagery with ∼10 m spatial resolution across an 11km wide swath. Radiance data are obtained in eight spectral bands (355, 380, 445, 470, 555, 660, 865, 935 nm). Dual photoelastic modulators (PEMs), achromatic quarter-wave plates, and wire-grid polarizers also enable imagery of the linear polarization Stokes components Q and U at 470, 660, and 865 nm. During January-February 2013, AirMSPI data were acquired over California as part of NASA's Polarimeter Definition Experiment (PODEX), a field campaign designed to refine requirements for the future Aerosol-Cloud-Ecosystem (ACE) satellite mission. Observations of aerosols, low- and mid-level cloud fields, cirrus, aircraft contrails, and clear skies were obtained over the San Joaquin Valley and the Pacific Ocean during PODEX. Example radiance and polarization images are presented to illustrate some of the instrument's capabilities. © 2013 SPIE.
• Diner, D. J., Xu, F., Garay, M. J., Martonchik, J. V., Rheingans, B. E., Geier, S., Davis, A., Hancock, B. R., Jovanovic, V. M., Bull, M. A., Capraro, K., Chipman, R. A., & McClain, S. C. (2013). The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI): A new tool for aerosol and cloud remote sensing. Atmospheric Measurement Techniques, 6(8), 2007-2025.
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  Abstract: The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) is an eight-band (355, 380, 445, 470, 555, 660, 865, 935 nm) pushbroom camera, measuring polarization in the 470, 660, and 865 nm bands, mounted on a gimbal to acquire multiangular observations over a ±67 along-track range. The instrument has been flying aboard the NASA ER-2 high altitude aircraft since October 2010. AirMSPI employs a photoelastic modulator-based polarimetric imaging technique to enable accurate measurements of the degree and angle of linear polarization in addition to spectral intensity. A description of the AirMSPI instrument and ground data processing approach is presented. Example images of clear, hazy, and cloudy scenes over the Pacific Ocean and California land targets obtained during flights between 2010 and 2012 are shown, and quantitative interpretations of the data using vector radiative transfer theory and scene models are provided to highlight the instrument's capabilities for determining aerosol and cloud microphysical properties and cloud 3-D spatial distributions. Sensitivity to parameters such as aerosol particle size distribution, ocean surface wind speed and direction, cloud-top and cloud-base height, and cloud droplet size is discussed. AirMSPI represents a major step toward realization of the type of imaging polarimeter envisioned to fly on NASA's Aerosol-Cloud-Ecosystem (ACE) mission in the next decade. © Author(s) 2013.
• Diner, D. J., Feng, X. u., Martonchik, J. V., Rheingans, B. E., Geier, S., Jovanovic, V. M., Davis, A., Chipman, R. A., & McClain, S. C. (2012). Exploration of a polarized surface bidirectional reflectance model using the ground-based multiangle spectropolarimetric imager. Atmosphere, 3(4), 591-619.
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  Abstract: Accurate characterization of surface reflection is essential for retrieval of aerosols using downward-looking remote sensors. In this paper, observations from the Ground-based Multiangle SpectroPolarimetric Imager (GroundMSPI) are used to evaluate a surface polarized bidirectional reflectance distribution function (PBRDF) model. GroundMSPI is an eight-band spectropolarimetric camera mounted on a rotating gimbal to acquire pushbroom imagery of outdoor landscapes. The camera uses a very accurate photoelastic-modulator-based polarimetric imaging technique to acquire Stokes vector measurements in three of the instrument's bands (470, 660, and 865 nm). A description of the instrument is presented, and observations of selected targets within a scene acquired on 6 January 2010 are analyzed. Data collected during the course of the day as the Sun moved across the sky provided a range of illumination geometries that facilitated evaluation of the surface model, which is comprised of a volumetric reflection term represented by the modified Rahman-Pinty-Verstraete function plus a specular reflection term generated by a randomly oriented array of Fresnel-reflecting microfacets. While the model is fairly successful in predicting the polarized reflection from two grass targets in the scene, it does a poorer job for two manmade targets (a parking lot and a truck roof), possibly due to their greater degree of geometric organization. Several empirical adjustments to the model are explored and lead to improved fits to the data. For all targets, the data support the notion of spectral invariance in the angular shape of the unpolarized and polarized surface reflection. As noted by others, this behavior provides valuable constraints on the aerosol retrieval problem, and highlights the importance of multiangle observations. © 2012 by the authors.
• Myhre, G., Hsu, W., Peinado, A., LaCasse, C., Brock, N., Chipman, R. A., & Pau, S. (2012). Liquid crystal polymer full-stokes division of focal plane polarimeter. Optics Express, 20(25), 27393-27409.
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  PMID: 23262690;Abstract: A division-of-focal-plane polarimeter based on a dichroic dye and liquid crystal polymer guest-host system is presented. Two Stokes polarimeters are demonstrated: a linear Stokes and the first ever Full-Stokes division-of-focal-plane polarimeter. The fabrication, packaging, and characterization of the systems are presented. Finally, optimized polarimeter designs are discussed for future works. © 2012 Optical Society of America.
• Noble, H. D., & Chipman, R. A. (2012). Mueller matrix roots algorithm and computational considerations. Optics Express, 20(1), 17-31.
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  PMID: 22274325;Abstract: Recently, an order-independent Mueller matrix decomposition was proposed in an effort to elucidate the nine depolarization degrees of freedom [Handbook of Optics, Vol. 1 of Mueller Matrices (2009)]. This paper addresses the critical computational issues involved in applying this Mueller matrix roots decomposition, along with a review of the principal matrix root and common methods for its calculation. The calculation of the pth matrix root is optimized around p = 105 for a 53 digit binary double precision calculation. A matrix roots algorithm is provided which incorporates these computational results. It is applied to a statistically significant number of randomly generated physical Mueller matrices in order to gain insight on the typical ranges of the depolarizing Matrix roots parameters. Computational techniques are proposed which allow singular Mueller matrices and Mueller matrices with a half-wave of retardance to be evaluated with the matrix roots decomposition. © 2011 Optical Society of America.
• Noble, H. D., McClain, S. C., & Chipman, R. A. (2012). Mueller matrix roots depolarization parameters. Applied Optics, 51(6), 735-744.
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  PMID: 22358163;Abstract: The Mueller matrix roots decomposition recently proposed by Chipman in [1] and its three associated families of depolarization (amplitude depolarization, phase depolarization, and diagonal depolarization) are explored. Degree of polarization maps are used to differentiate among the three families and demonstrate the unity between phase and diagonal depolarization, while amplitude depolarization remains a distinct class. Three families of depolarization are generated via the averaging of different forms of two nondepolarizing Mueller matrices. The orientation of the resulting depolarization follows the cyclic permutations of the Pauli spin matrices. The depolarization forms of Mueller matrices from two scattering measurements are analyzed with the matrix roots decomposition-a sample of ground glass and a graphite and wood pencil tip. © 2012 Optical Society of America.
• Young, G., & Chipman, R. A. (2012). Skew aberration analysis. Proceedings of SPIE - The International Society for Optical Engineering, 8550.
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  Abstract: Skew aberration is an intrinsic rotation of polarization states due to the geometric transformation of local coordinates via parallel transport of vectors. Skew aberration is a component of polarization aberration but is independent of the incident polarization state or the coatings applied to the optical interface. Skew aberration occurs even for rays propagating through ideal, aberration-free, and non-polarizing optical systems. Skew aberration is typically a small effect in optical systems but it should be of concern in microlithography optics and other polarization sensitive systems with high numerical aperture and large field of view. The variation of skew aberration across the exit pupil causes undesired polarization components in the exit pupil. Typically cross polarized satellites form around the point spread function (PSF). The PSF and optical transfer function (OTF) are different from ideal PSF or OTF and thus the image quality can be degraded. In the presence of polarization aberration, the scalar PSF and OTF can be generalized to a two-by-two point spread matrix (PSM) or optical transfer matrix (OTM) in Jones matrix notation. We demonstrate analysis of skew aberration effects separate from other polarization aberrations by using a two-by-two PSM and OTM of the U.S. patent 2,896,506. We demonstrate a relationship between skew aberration, Lagrange invariant and the sum of the individual surface powers of the system, using paraxial optics. © 2012 SPIE.
• Denninghoff, K. R., Sieluzycka, K. B., Hendryx, J. K., Ririe, T. J., DeLuca, L., & Chipman, R. A. (2011). Retinal oximeter for the blue-green oximetry technique. Journal of Biomedical Optics, 16(10).
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  PMID: 22029366;PMCID: PMC3206928;Abstract: Retinal oximetry offers potential for noninvasive assessment of central venous oxyhemoglobin saturation (SO 2) via the retinal vessels but requires a calibrated accuracy of ±3% saturation in order to be clinically useful. Prior oximeter designs have been hampered by poor saturation calibration accuracy.We demonstrate that the bluegreen oximetry (BGO) technique can provide accuracy within ±3% in swine when multiply scattered light from blood within a retinal vessel is isolated. A noninvasive on-axis scanning retinal oximeter (ROx-3) is constructed that generates a multiwavelength image in the range required for BGO. A field stop in the detection pathway is used in conjunction with an anticonfocal bisecting wire to remove specular vessel reflections and isolate multiply backscattered light from the blood column within a retinal vessel. This design is tested on an enucleated swine eye vessel and a retinal vein in a human volunteer with retinal SO 2 measurements of ∼1 and ∼65%, respectively. These saturations, calculated using the calibration line from earlier work, are internally consistent with a standard error of the mean of ±2% SO 2. The absolute measures are well within the expected saturation range for the site (-1 and 63%). This is the first demonstration of noninvasive on-axis BGO retinal oximetry. © 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).
• Mahler, A., & Chipman, R. A. (2011). Polarization state generator: A polarimeter calibration standard. Applied Optics, 50(12), 1726-1734.
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  PMID: 21509064;Abstract: A polarization state generator (PSG) was built to generate light having a degree of linear polarization (DoLP) varying from 0.0005 to 0.4 with 0.0005 uncertainty. The PSG operates by tilting a plane parallel SF11 glass plate in a nearly unpolarized beam. The DoLP of collimated, unpolarized light passing through a plane parallel plate over a defined range of field angles can be calculated from theory, and the PSG was intended to act as a calibration standard based on this calculation. Several effects make the DoLP distribution as a function of field and tilt plate difficult to model to the desired 0.0005 uncertainty: source DoLP and intensity nonuniformity, lens surface diattenuation, and errors in optical alignment. Because of these effects, modeled DoLP was not used as a standard. Instead, DoLP was characterized with repeatability of 0.0005. © 2011 Optical Society of America.
• Mahler, A., Diner, D. J., & Chipman, R. A. (2011). Analysis of static and time-varying polarization errors in the multiangle spectropolarimetric imager. Applied Optics, 50(14), 2080-2087.
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  PMID: 21556109;Abstract: Multiangle Spectropolarimetric Imager (MSPI) sensitivity to static and time-varying polarization errors is examined. For a system without noise, static polarization errors are accurately represented by the calibration coefficients, and therefore do not impede correct mapping of measured to input Stokes vectors. But noise is invariably introduced during the detection process, and static polarization errors reduce the system's signal-to-noise ratio (SNR) by increasing noise sensitivity. Noise sensitivity is minimized by minimizing the condition number of the system data reduction matrix [Appl. Opt. 41, 619 (2002)]. The sensitivity of condition numbers to static polarization errors is presented. The condition number of the nominal MSPI data reduction matrix is approximately 1.1 or less for all fields. The increase in the condition number above 1 results primarily from a quarter wave plate and mirror coating retardance magnitude errors. Sensitivity of the degree of linear polarization (DoLP) error with respect to timevarying diattenuation and retardance error was used to set a time-varying diattenuation magnitude tolerance of 0.005 and a time-varying retardance magnitude tolerance of ± 0:2°. A Monte Carlo simulation of the calibration and measurements using anticipated static and time-varying errors indicates that MSPI has a probability of 0.9 of meeting its 0.005 DoLP uncertainty requirement. © 2011 Optical Society of America.
• Mahler, A., McClain, S., & Chipman, R. (2011). Achromatic athermalized retarder fabrication. Applied Optics, 50(5), 755-765.
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  PMID: 21343998;Abstract: A method for fabricating an achromatic, athermalized quarter-wave retarder is presented that involves monitoring retardance during polishing. A design specified by thicknesses alone is unlikely to meet specification due to uncertainties in birefringence. This method facilitates successful fabrication to a retardance specification despite these uncertainties. A retarder made from sapphire, MgF2, and quartz was designed, fabricated, and its performance validated for the 0.470 to 0.865 μm wavelength region. Its specifications are as follows: at wavebands centered at 0.470, 0.660, and 0.865 μm the band-averaged retardance should be 90° ± 10° for all fields and retardance should change less than 0.1° for a 1° change in temperature. Retarder fabrication accommodated birefringence and thickness uncertainties via the following steps. The first plate was polished to a target thickness. The retardance spectrum of the first plate was then measured and used to determine a retardance target for the second plate. The retardance spectrum of the combined first and second plates was then used to specify a retardance target for the third plate. The retardance spectrum of the three plates in combination was then used to determine when the final thickness of the third plate was reached. © 2011 Optical Society of America.
• Mawet, D., Murakami, N., Delacroix, C., Serabyn, E., Absil, O., Baba, N., Baudrand, J., Boccaletti, A., Burruss, R., Chipman, R., Forsberg, P., Habraken, S., Hamaguchi, S., Hanot, C., Ise, A., Karlsson, M., Kern, B., Krist, J., Kuhnert, A., , Levine, M., et al. (2011). Taking the vector vortex coronagraph to the next level for ground- and space-based exoplanet imaging instruments: Review of technology developments in the USA, Japan, and Europe. Proceedings of SPIE - The International Society for Optical Engineering, 8151.
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  Abstract: The Vector Vortex Coronagraph (VVC) is one of the most attractive new-generation coronagraphs for ground- and space-based exoplanet imaging/characterization instruments, as recently demonstrated on sky at Palomar and in the laboratory at JPL, and Hokkaido University. Manufacturing technologies for devices covering wavelength ranges from the optical to the mid-infrared, have been maturing quickly. We will review the current status of technology developments supported by NASA in the USA (Jet Propulsion Laboratory-California Institute of Technology, University of Arizona, JDSU and BEAMCo), Europe (University of Li'ege, Observatoire de Paris- Meudon, University of Uppsala) and Japan (Hokkaido University, and Photonics Lattice Inc.), using liquid crystal polymers, subwavelength gratings, and photonics crystals, respectively. We will then browse concrete perspectives for the use of the VVC on upcoming ground-based facilities with or without (extreme) adaptive optics, extremely large ground-based telescopes, and space-based internal coronagraphs. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
• Mawet, D., Serabyn, E., Moody, D., Kern, B., Niessner, A., Kuhnert, A., Shemo, D., Chipman, R., McClain, S., & Trauger, J. (2011). Recent results of the second generation of vector vortex coronagraphs on the high-contrast imaging testbed at JPL. Proceedings of SPIE - The International Society for Optical Engineering, 8151.
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  Abstract: The Vector Vortex Coronagraph (VVC) is an attractive internal coronagraph solution to image and characterize exoplanets. It provides four key pillars on which efficient high contrast imaging instruments can be built for ground- and space-based telescopes: small inner working angle, high throughput, clear off-axis discovery space, and simple layout. We present the status of the VVC technology development supported by NASA. We will review recent results of the optical tests of the second-generation topological charge 4 VVC on the actively corrected High Contrast Imaging Testbed (HCIT) at the Jet Propulsion Laboratory (JPL). New VVC contrast records have been established. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
• Milster, T. D., Noble, H., Ford, E., Dallas, W., Chipman, R. A., Matsubara, I., Unno, Y., McClain, S., Khulbe, P., Lam, W. S., & Hansen, D. (2011). Polarization holograms for source-mask optimization. Proceedings of SPIE - The International Society for Optical Engineering, 7973.
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  Abstract: A new technique is introduced to replace DOEs that are used for illumination in lithographic projectors with polarization computer generated holograms (PCGHs) that produce both arbitrary intensity and arbitrary polarization state in the illumination pupil. The additional capability of arbitrary polarization state adds an additional degree of freedom for source-mask optimization. The PCGHs are similar in design and construction to DOEs, but they incorporate polarizationsensitive elements. Three experiments are described that demonstrate different configurations of PCGHs deigned to produce a tangentially polarized ring. Measurements of ratio of polarization and polarization orientation indicate that all three configurations performed well. Experimetns are performed with visible (λ = 632.8nm) light. © 2011 SPIE.
• Noble, H. D., Lam, W. T., Dallas, W., Chipman, R. A., Matsubara, I., Unno, Y., McClain, S. C., Khulbe, P., Hansen, D., & Milster, T. D. (2011). Square-wave retarder for polarization computer-generated holography. Applied Optics, 50(20), 3703-3710.
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  PMID: 21743584;Abstract: An etched calcite square-wave retarder is designed, fabricated, and demonstrated as an illuminator for an interlaced polarization computer-generated hologram (PCGH). The calcite square-wave retarder enables alternating columns of orthogonal linear polarizations to illuminate the interlaced PCGH. Together, these components produce a speckled, tangentially polarized PCGH diffraction pattern with a measured ratio of polarization of 84% and a degree of linear polarization of 0.81. An experimental alignment tolerance analysis is also reported. © 2011 Optical Society of America.
• Onishi, M., Crabtree, K., & Chipman, R. A. (2011). Formulation of rigorous coupled-wave theory for gratings in bianisotropic media. Journal of the Optical Society of America A: Optics and Image Science, and Vision, 28(8), 1747-1758.
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  PMID: 21811338;Abstract: A formulation of rigorous coupled-wave theory for diffraction gratings in bianisotropic media that exhibit linear birefringence and/or optical activity is presented. The symmetric constitutive relations for bianisotropic materials are adopted. All of the incident, exiting, and grating materials can be isotropic, uniaxial, or biaxial, with or without optical activity. The principal values of the electric permittivity tensor, the magnetic permeability tensor, and the gyrotropic tensor of the media can take arbitrary values, and the principal axes may be arbitrarily and independently oriented. Procedures for Fourier expansion of Maxwell's equations are described. Distinctive polarization coupling effects due to optical activity are observed in sample calculations. © 2011 Optical Society of America.
• Venkatasubbarao, S., Dixon, C. E., Chipman, R., Scherer, A., Beshay, M., Kempen, L. U., Ganesh, J., Yan, H., Puccio, A., Okonkwo, D., McClain, S., Gilbert, N., & Vyawahare, S. (2011). Field-based multiplex and quantitative assay platforms for diagnostics. Proceedings of SPIE - The International Society for Optical Engineering, 8029.
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  Abstract: The U.S. military has a continued interest in the development of handheld, field-usable sensors and test kits for a variety of diagnostic applications, such as traumatic brain injury (TBI) and infectious diseases. Field-use presents unique challenges for biosensor design, both for the readout unit and for the biological assay platform. We have developed robust biosensor devices that offer ultra-high sensitivity and also meet field-use needs. The systems under development include a multiplexed quantitative lateral flow test strip for TBI diagnostics, a field test kit for the diagnosis of pathogens endemic to the Middle East, and a microfluidic assay platform with a label-free reader for performing complex biological automated assays in the field. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
• Yun, G., Crabtree, K., & Chipman, R. A. (2011). Skew aberration: A form of polarization aberration. Optics Letters, 36(20), 4062-4064.
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  PMID: 22002386;Abstract: We define a new class of aberration, skew aberration, which is a component of polarization aberration. Skew aberration is an intrinsic rotation of polarization states due to the geometric transformation of local coordinates, independent of coatings and interface polarization. Skew aberration in a radially symmetric system has the form of a circular retardance tilt plus coma aberration. Skew aberration causes undesired polarization distribution in the exit pupil. We demonstrate statistics on skew aberration of 2383 optical systems described in Code V's U.S. patent library [Code V Version 10.3 (Synopsys, 2011), pp. 22-24]; the mean skew aberration is 0:89° and the standard deviation is 1:37°. The maximum skew aberration found is 17:45° and the minimum is -11:33°. U.S. patent 2,896,506, which has-7:01° of skew aberration, is analyzed in detail. Skew aberration should be of concern in microlithography optics and other high NA and large field of view optical systems. © 2011 Optical Society of America.
• Yun, G., Crabtree, K., & Chipman, R. A. (2011). Three-dimensional polarization ray-tracing calculus I: Definition and diattenuation. Applied Optics, 50(18), 2855-2865.
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  PMID: 21691348;Abstract: A three-by-three polarization ray-tracing matrix method for polarization ray tracing in optical systems is presented for calculating the polarization transformations associated with ray paths through optical systems. The method is a three-dimensional generalization of the Jones calculus. Reflection and refraction algorithms are provided. Diattenuation of the optical system is calculated via singular value decomposition. Two numerical examples, a three fold-mirror system and a hollow corner cube, demonstrate the method. © 2011 Optical Society of America.
• Yun, G., McClain, S. C., & Chipman, R. A. (2011). Three-dimensional polarization ray-tracing calculus II: Retardance. Applied Optics, 50(18), 2866-2874.
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  PMID: 21691349;Abstract: The concept of retardance is critically analyzed for ray paths through optical systems described by a three-by-three polarization ray-tracing matrix. Algorithms are presented to separate the effects of retardance from geometric transformations. The geometric transformation described by a "parallel transport matrix" characterizes nonpolarizing propagation through an optical system, and also provides a proper relationship between sets of local coordinates along the ray path. The proper retardance is calculated by removing this geometric transformation from the three-by-three polarization ray-tracing matrix. Two rays with different ray paths through an optical system can have the same polarization ray-tracing matrix but different retardances. The retardance and diattenuation of an aluminum-coated three fold-mirror system are analyzed as an example. © 2011 Optical Society of America.
• Chipman, R. A. (2010). Challenges in polarization ray tracing. Optics InfoBase Conference Papers.
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  Abstract: New polarization methods allow the ray tracing simulation of polarization critical components, including multilayer biaxial films, anisotropic and gyrotropic crystals, electro-optical, magneto-optical, and stressoptical modulators, photonic crystals and meta-materials. © OSA / IODC/OF&T 2010.
• Chipman, R. A. (2010). Challenges in polarization ray tracing. Proceedings of SPIE - The International Society for Optical Engineering, 7652.
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  Abstract: New polarization methods allow the ray tracing simulation of polarization critical components, including multilayer biaxial films, anisotropic and gyrotropic crystals, electro-optical, and magneto-optical materials bring many new challenges. © 2010 Copyright SPIE - The International Society for Optical Engineering.
• Crabtree, K., & Chipman, R. (2010). Polarization conversion cube-corner retroreflector. Applied Optics, 49(30), 5882-5890.
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  PMID: 20962954;Abstract: Polarization conversion cube-corner retroreflectors rotate the major axis of the incident electric field by 90°. We show that polarization conversion cube-corner retroreflectors cannot be created with isotropic reflecting surfaces, but can be created by incorporating nonisotropic reflecting surfaces. Two types are considered - cube corners with surfaces having elliptical eigenstates and cube corners having subwave- length gratings. Implementations that use subwavelength surface relief phase gratings are investigated, and three examples are shown. © 2010 Optical Society of America.
• Daugherty, B., & Chipman, R. (2010). Low polarization microscope objectives. Optics InfoBase Conference Papers.
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  Abstract: Microscope objectives used for biaxial ellipsometry require small levels of polarization aberrations. The approach outlined in this paper allows the design and fabrication of microscope objectives with twelve times less diattenuation than commercially available objectives. © 2010 Optical Society of America.
• Daugherty, B., & Chipman, R. (2010). Low polarization microscope objectives. Proceedings of SPIE - The International Society for Optical Engineering, 7652.
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  Abstract: Low polarization, high numerical aperture microscope objectives ideal for polarization sensitive applications are designed, fabricated, and measured. A microscope objective is designed to meet the application requirements using Code V. Performance of typical AR coatings is examined and determined to be insufficient to meet the polarization performance desired. Custom AR coatings are optimized using an in house polarization ray tracing program to reduce the objectives diattenuation. The resulting microscope objectives perform about 5 times better than our low polarization Nikon objectives. © 2010 Copyright SPIE - The International Society for Optical Engineering.
• Diner, D. J., Ackerman, T. P., Braverman, A. J., Bruegge, C. J., Chopping, M. J., Clothiaux, E. E., Davies, R., Girolamo, L. D., Kahn, R. A., Knyazikhin, Y., Liu, Y., Marchand, R., Martonchik, J. V., Muller, J., Nolin, A. W., Pinty, B., Verstraete, M. M., Wu, D. L., Garay, M. J., , Kalashnikova, O. V., et al. (2010). Ten years of MISR observations from Terra: Looking back, ahead, and in between. International Geoscience and Remote Sensing Symposium (IGARSS), 1297-1299.
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  Abstract: The Multi-angle Imaging SpectroRadiometer (MISR) instrument has been collecting global Earth data from NASA's Terra satellite since February 2000. With its nine along-track view angles, four visible/near-infrared spectral bands, intrinsic spatial resolution of 275 m, and stable radiometric and geometric calibration, no instrument that combines MISR's attributes has previously flown in space. The more than 10-year (and counting) MISR data record provides unprecedented opportunities for characterizing long-term trends in aerosol, cloud, and surface properties, and includes 3-D textural information conventionally thought to be accessible only to active sensors. © 2010 IEEE.
• Diner, D. J., Davis, A., Hancock, B., Geier, S., Rheingans, B., Jovanovic, V., Bull, M., Rider, D. M., Chipman, R. A., Mahler, A., & McClain, S. C. (2010). First results from a dual photoelastic-modulator-based polarimetric camera. Applied Optics, 49(15), 2929-2946.
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  PMID: 20490256;Abstract: We report on the construction and calibration of a dual photoelastic-modulator (PEM)-based polarimetric camera operating at 660 nm. This camera is our first prototype for a multispectral system being developed for airborne and spaceborne remote sensing of atmospheric aerosols. The camera includes a dual-PEM assembly integrated into a three-element, low-polarization reflective telescope and provides both intensity and polarization imaging. A miniaturized focal-plane assembly consisting of spectral filters and patterned wire-grid polarizers provides wavelength and polarimetric selection. A custom push-broom detector array with specialized signal acquisition, readout, and processing electronics captures the radiometric and polarimetric information. Focal-plane polarizers at orientations of 0° and -45° yield the normalized Stokes parameters q = Q/I and u = U/I respectively, which are then coregistered to obtain degree of linear polarization (DOLP) and angle of linear polarization. Laboratory test data, calibration results, and outdoor imagery acquired with the camera are presented. The results show that, over a wide range of DOLP, our challenging objective of uncertainty within ±0.005 has been achieved. © 2010 Optical Society of America.
• Noble, H., Ford, E., Dallas, W., Chipman, R. A., Matsubara, I., Unno, Y., McClain, S., Khulbe, P., Hansen, D., & Milster, T. D. (2010). Polarization synthesis by computer-generated holography using orthogonally polarized and correlated speckle patterns. Optics Letters, 35(20), 3423-3425.
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  PMID: 20967087;Abstract: An interlaced polarization computer-generated hologram [PCGH] is designed to produce specific irradiance and polarization states in the image plane. The PCGH produces a tangentially polarized annular pattern with correlated speckle, which is achieved by a novel application of the diffuser optimization method. Alternating columns of orthogonal linear polarizations illuminate an interlaced PCGH, producing a ratio of polarization of 88% measured on a fabricated sample. The demonstrated technique can be applied to designs for arbitrary irradiance and polarization states in the image plane. © 2010 Optical Society of America.
• Sze, W., McClain, S., Smith, G. A., & Chipman, R. (2010). Ray tracing in biaxial materials. Proceedings of SPIE - The International Society for Optical Engineering, 7652.
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  Abstract: Algorithms for polarization ray tracing biaxial materials and calculating the directions of ray propagation and energy flow, the refractive indices, and the coupling coefficients for all four resultant reflected and transmitted rays are presented. Examples of polarization state maps, retardance maps and diattenuation maps are generated as a function of angle of incidence for comparing plane parallel plate systems with uniaxial and biaxial materials. © 2010 Copyright SPIE - The International Society for Optical Engineering.
• Sze, W., McClain, S., Smith, G., & Chipman, R. (2010). Ray tracing in biaxial materials. Optics InfoBase Conference Papers.
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  Abstract: Algorithms for polarization ray tracing biaxial materials and calculating the directions of ray propagation and energy flow, the refractive indices, and the coupling coefficients for all four resultant reflected and transmitted rays are presented. © 2010 Optical Society of America.
• Yun, G., & Chipman, R. A. (2010). Three-dimensional polarization ray tracing, retardance. Optics InfoBase Conference Papers.
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  Abstract: The retardance associated with a three-by-three polarization ray tracing matrix P is analyzed. A method to separate the geometrical transformation from the "physical" retardance is presented using a nonpolarizing ray tracing matrix Q. © 2010 Optical Society of America.
• Yun, G., & Chipman, R. A. (2010). Three-dimensional polarization ray tracing, retardance. Proceedings of SPIE - The International Society for Optical Engineering, 7652.
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  Abstract: The retardance associated with a three-by-three polarization ray tracing matrix is analyzed. The retardance of the polarization ray tracing matrix contains both a geometrical transformation and the polarization properties of diattenuation and retardance associated with a ray path through the optical and polarization elements. A method using parallel transport of transverse vectors is able to separate the geometrical transformation from the "physical" retardance, allowing the retardance to be calculated. A non-polarizing ray tracing matrix provides proper local coordinates to calculate the physical retardance without the geometrical transformation. © 2010 Copyright SPIE - The International Society for Optical Engineering.
• Yun, G., Crabtree, K., & Chipman, R. A. (2010). Three-dimensional polarization ray tracing and diattenuation calculation. Optics InfoBase Conference Papers.
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  Abstract: A three-by-three polarization ray tracing matrix P for calculating polarization transformations associated with ray paths through optical systems is presented. Diattenuation of the optical system is calculated via singular value decomposition of the P matrix. © 2010 Optical Society of America.
• Yun, G., Crabtree, K., & Chipman, R. A. (2010). Three-dimensional polarization ray tracing and diattenuation calculation. Proceedings of SPIE - The International Society for Optical Engineering, 7652.
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  Abstract: A three-by-three polarization ray tracing matrix method for polarization ray tracing in optical systems is presented for calculating the polarization transformations associated with ray paths through optical systems. The method is a three dimensional generalization of a Jones matrix. Diattenuation of the optical system is calculated via singular value decomposition. © 2010 Copyright SPIE - The International Society for Optical Engineering.
• Lam, W. T., Chipman, R. A., Twietmeyer, K. M., Zhou, Y., Denninghoff, K. R., Elsner, A. E., & Burns, S. A. (2009). Depolarization properties of the normal human fovea measured by the GDx-MM. Proceedings of SPIE - The International Society for Optical Engineering, 7461.
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  Abstract: A custom imaging Mueller matrix retinal polarimeter (the GDx-MM) is built. Mueller matrix images of normal human fovea were acquired with the GDx-MM over a 9°field at 780nm and have been analyzed for depolarization index and the variation of degree of polarization with incident polarization state. The degree of polarization (DoP) was often above 50% and varied in complex ways as a function of the incident polarization states. The depolarization properties around the macula loosely correlated with the retardance image. High spatial frequency depolarizing structures were evident throughout the fovea. © 2009 Copyright SPIE - The International Society for Optical Engineering.
• McEldowney, S. C., Shemo, D. M., & Chipman, R. A. (2009). Photoaligned liquid crystal polymers for space variant polarization control. Optics InfoBase Conference Papers.
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  Abstract: We present developments using photo-aligned liquid crystal polymers for creating space variant polarization control. We demonstrate novel components which create both systematic and random polarization orientation profiles. Theoretical and experimental properties of vortex retarders and speckle control components are presented. © 2009 OSA.
• Noble, H., Lam, W., & Chipman, R. A. (2009). Inferring the orientation of texture from polarization parameters. Proceedings of SPIE - The International Society for Optical Engineering, 7461.
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  Abstract: It is shown that once the diffusely scattered polarization properties are calibrated, the texture orientation can be calculated directly from diattenuation and retardance. Polarization scattering properties are studied for a rough aluminum surface with one-dimensional rough texture and well-defined orientation. Functions of Mueller matrix elements related to sample orientation about the normal via the arctangent function are investigated. The Mueller matrix bidirectional reflectance distribution function is measured for a linearly sanded aluminum sample. Sinusoidal fits to the Mueller matrix show that the angular orientation of the data can be recovered explicitly from its properties. © 2009 Copyright SPIE - The International Society for Optical Engineering.
• Ubach, C. C., Chipman, R. A., & Potter, D. E. (2009). PEPPER: Polarization-encoding differential photometer and polarimeter. Proceedings of SPIE - The International Society for Optical Engineering, 7461.
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  Abstract: PEPPER is a high-speed differential Polarization-Encoded Photometer and Polarimeter developed in the Center for Astronomical Adaptive Optics at the University of Arizona, Tucson, by Dr. Dan Potter and Matthew Graham. PEPPER is capable of acting as a high-speed polarimeter by using electro-optical switching to chop between standard star and target star, and between in and out-feature bandpass filter at frequencies fast enough to suppress atmospheric variations. PEPPER is capable of either high-speed polarimetry or differential photometry using a combination of simultaneous imaging and electro-optical switching. In the differential photometry mode, PEPPER utilizes the electro-optical switching to calibrate instrumental and atmospheric photometric variation. This technique coupled with a zero-read noise photon counting detector achieves photon noise limited results demonstrated to an accuracy of less than 1 part in 10 5. Herein we present the design concept behind the photometer and the polarimeter mode of PEPPER, as well as, results from observations in the differential photometer mode at the Steward 90 inch telescope, at the Kitt Peak National Observatory, Tucson, Arizona. Results from the analysis of near IR polarimetry observations of young stars with circumstellar disks taken at the Gemini North Telescope with the Hokupa'a adaptive optics system are also presented. © 2009 Copyright SPIE - The International Society for Optical Engineering.
• Yun, G., & Chipman, R. A. (2009). Retardance in three-dimensional polarization ray tracing. Proceedings of SPIE - The International Society for Optical Engineering, 7461.
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  Abstract: A three-by-three polarization ray tracing matrix P which is defined in global coordinates characterizes the polarization transformations associated with single ray through optical system. The P matrix contains both a geometrical transformation effect and the polarization characteristics of diattenuation and retardance from the optical and polarization elements. In order to separate the geometrical transformation and calculate the "physical" retardance, a non-polarizing ray tracing matrix Q is used. The diattenuation and the retardance of a dove prism are analyzed as an example. © 2009 Copyright SPIE - The International Society for Optical Engineering.
• Denninghoff, K. R., Salyer, D. A., Basavanthappa, S., Park, R. I., & Chipman, R. A. (2008). Blue-green spectral minimum correlates with oxyhemoglobin saturation in vivo. Journal of Biomedical Optics, 13(5).
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  PMID: 19021438;Abstract: An imaging multi-spectral retinal oximeter with intravitrial illumination is used to perform the first in vivo test of the blue-green minima shift oximetry method (BGO) in swine eyes [K. R. Dennighoff, R. A. Chipman, and L. W. Hillman, Opt. Lett. 31, 924-926 (2006); J. Biomed. Opt. 12, 034020 (2007).] A fiber optic intravitreal illuminator inserted through the pars plana was coupled to a monochromator and used to illuminate the retina from an angle. A camera viewing through the cornea recorded a series of images at each wavelength. This intravitreal light source moves the specular vessel glint away from the center of the vessel and directly illuminates the fundus behind most blood vessels. These two conditions combine to provide accurate measurements of vessel and perivascular reflectance. Equations describing these different light paths are solved, and BGO is used to evaluate large retinal vessels. In order to test BGO calibration in vivo, data were acquired from swine with varied retinal arterial oxyhemoglobin saturations (60-100% saturation.). The arterial saturations determined using BGO to analyze the multispectral image sets showed excellent correlation with co-oximeter data (r 2=0.98, and residual error ±3.4% saturation) and are similar to results when hemoglobin and blood were analyzed using this technique. © 2008 Society of Photo-Optical Instrumentation Engineers.
• Denninghoff, K., Walter, F. G., Langa, A. J., Yao, H. e., & Chipman, R. A. (2008). Spectrophotometry of hydroxocobalamin and hemoglobin reveals production of an unanticipated methemoglobin variant. Clinical Toxicology, 46(6), 545-550.
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  PMID: 18584368;Abstract: Introduction. Cyanide-poisoned patients often require pulse oximetry and co-oximetry to measure oxyhemoglobin, deoxyhemoglobin, carboxyhemoglobin, and methemoglobin. These and other critical laboratory measurements can be confounded by the cyanide antidote hydroxocobalamin. The postulated mechanism of this confounding is direct optical interference. Methods. The spectra of swine hemoglobin with and without hydroxocobalamin were measured from 450-800 nm. The resulting complex spectrum was divided into hemoglobin, hydroxocobalamin, and a remainder spectrum. Results. The remainder spectrum appears to be a methemoglobin variant quantitatively dependant on the amount of hydroxocobalamin added to the hemoglobin solution and the presence of oxygen. The Pearson's correlation coefficient comparing the known swine methemoglobin spectrum with the remainder spectrum reveals a very high degree of correlation (r2=0.986). Conclusion. This is the first study to document methemoglobin formation caused by hydroxocobalamin. Further studies are needed in vitro and in vivo to assess this previously unreported methemoglobin variant. Copyright © Informa Healthcare USA, Inc.
• Diner, D. J., Michael, M., Chipman, R. A., Davis, A., Cairns, B., Davies, R., Kahn, R. A., Muller, J., & Torres, O. (2008). WindCam and MSPI: Two cloud and aerosol instrument concepts derived from Terra/MISR heritage. Proceedings of SPIE - The International Society for Optical Engineering, 7081.
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  Abstract: The Multi-angle Imaging SpectroRadiometer (MISR) has been acquiring global cloud and aerosol data from polar orbit since February 2000. MISR acquires moderately high-resolution imagery at nine view angles from nadir to 70.5°, in four visible/near-infrared spectral bands. Stereoscopic parallax, time lapse among the nine views, and the variation of radiance with angle and wavelength enable retrieval of geometric cloud and aerosol plume heights, height-resolved cloud-tracked winds, and aerosol optical depth and particle property information. Two instrument concepts based upon MISR heritage are in development. The Cloud Motion Vector Camera, or WindCam, is a simplified version comprised of a lightweight, compact, wide-angle camera to acquire multiangle stereo imagery at a single visible wavelength. A constellation of three WindCam instruments in polar Earth orbit would obtain height-resolved cloud-motion winds with daily global coverage, making it a low-cost complement to a spaceborne lidar wind measurement system. The Multiangle SpectroPolarimetric Imager (MSPI) is aimed at aerosol and cloud microphysical properties, and is a candidate for the National Research Council Decadal Survey's Aerosol-Cloud-Ecosystem (ACE) mission. MSPI combines the capabilities of MISR with those of other aerosol sensors, extending the spectral coverage to the ultraviolet and shortwave infrared and incorporating high-accuracy Polarimetrie imaging. Based on requirements for the non-imaging Aerosol Polarimeter Sensor on NASA's Glory mission, a degree of linear polarization uncertainty of 0.5% is specified within a subset of the MSPI bands. We are developing a polarization imaging approach using photoelastic modulators (PEMs) to accomplish this objective.
• Mahler, A., Chipman, R., McClain, S. C., Diner, D. J., Davis, A., Raouf, N., Geier, S., & Hancock, B. (2008). Calibration and performance validation of optical elements in a photoelastic modulator-based polarimetric camera. International Geoscience and Remote Sensing Symposium (IGARSS), 3(1), III526-III529.
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  Abstract: As part of NASA's Instrument Incubator Program (IIP), we have been developing enabling technologies for the Multiangle SpectroPolarimetric Imager (MSPI), a candidate instrument for the Aerosol-Cloud-Ecosytem (ACE) mission. ACE is one of several satellite concepts identified in the 2007 National Research Council Earth Sciences Decadal Survey. MSPI is a multiangle, multispectral, high-accuracy polarization imager, and is envisioned to contain multiple cameras pointed at different viewing angles, with intensity imaging in several spectral bands between the ultraviolet and shortwave infrared, and accurate polarimetric imaging in a subset of the bands. To achieve a degree of linear polarization (DOLP) uncertainty of 1%, we temporally modulate the linear-polarization component of the incoming light at a rapid rate, enabling each detector within a focal-plane array combined with polarization analyzers to measure the relative proportions of the linear Stokes components Q or U to the total intensity I. Our system uses tandem photoelastic modulators (PEMs) within a reflective camera design. We report on the status of our prototype camera development, with particular emphasis on theoretical and experimental work on the required and measured performance of optical elements within the system including: the spectropolarimetric filters, quarter wave plates, and tandem PEMs. We also report on the end-to-end measurement and calibration of camera polarization aberrations using a custom polarization state generator (PSG). Careful design and control of scattered light enables the PSG to generate polarization states between DOLP of 0.07% and 40% with an uncertainty of 0.05%, making it a precision tool for polarimetric calibration and validation of MSPI. © 2008 IEEE.
• Mahler, A., Raouf, N. A., Smith, P. K., McClain, S. C., & Chipman, R. A. (2008). Minimizing instrumental polarization in the multiangle spectropolarimetric imager (MSPI) using diattenuation balancing between the three mirror coatings. Proceedings of SPIE - The International Society for Optical Engineering, 7013.
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  Abstract: Special enhanced silver mirror coatings were designed and fabricated to minimize the polarization introduced by a three-mirror off-axis high-accuracy telescope. A system diattenuation of approximately 1% in the VIS-NIR was achieved by both reducing the diattenuation from each mirror individually and by balancing the diattenuations introduced by the three mirrors over the spectral range. This process of low-polarization engineering involves minimizing system polarization introduced by surface geometry, thin film coatings and birefringent elements, and measuring the system. In this report we will outline a methodology to minimize instrumental polarization aberrations, with an emphasis on achieving low diattenuation in the MSPI camera, given its off-axis geometry and coating design constraints imposed by the space-based application. This polarization balancing technique for mirror coatings can be applied to astrophysics applications.
• McEldowney, S. C., Shemo, D. M., & Chipman, R. A. (2008). Vortex retarders produced from photo-aligned liquid crystal polymers. Optics Express, 16(10), 7295-7308.
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  PMID: 18545435;Abstract: We present developments using photo-aligned liquid crystal polymers for creating vortex retarders, halfwave retarders with a continuously variable fast axis. Polarization properties of components designed to create different polarization vortex modes are presented. We assess the viability of these components using the theoretical and experimental point spread functions and optical transfer functions in Mueller matrix format, point spread matrix (PSM) and optical transfer matrix (OTM). The measured PSM and OTM of these components in an optical system is very close to the theoretically predicted values thus showing that these components should provide excellent performance in applications utilizing polarized optical vortices. The impact of aberrations and of vortex retarder misalignment on the PSM and OTM are presented. © 2008 OSA.
• McEldowney, S. C., Shemo, D. M., Chipman, R. A., & Smith, P. K. (2008). Creating vortex retarders using photoaligned liquid crystal polymers. Optics Letters, 33(2), 134-136.
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  PMID: 18197216;Abstract: We present developments using photoaligned liquid crystal polymers for creating vortex retarders, half-wave retarders with a continuously variable fast axis. Polarization properties of components designed to create different polarization vortex modes are presented. We assess the viability of these components by using the theoretical and experimental point spread functions in Mueller matrix format, or a point spread matrix (PSM). The measured PSM of these components in an optical system is very close to the theoretically predicted values, thus showing that these components should provide excellent performance in applications utilizing polarized optical vortices. © 2008 Optical Society of America.
• Salyer, D. A., Denninghoff, K. R., Beaudry, N., Basavanthappa, S., Park, R. I., & Chipman, R. A. (2008). Diffuse spectral fundus reflectance measured using subretinally placed spectralon. Journal of Biomedical Optics, 13(4).
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  PMID: 19021332;Abstract: The diffuse fundus reflectance and the spectral transmittance of the swine sensory retina was measured in vivo using intravitreal illumination. Pars plana vitrectomy and intravitreal manipulations were performed on a female American Yorkshire domestic swine. Light from a scanning monochromator was coupled into a fiber optic intraocular illuminator inserted into the vitreous. A 1.93-mm 2 region of the illuminated fundus was imaged from an oblique illumination angle. Multispectral retinal images were acquired for four experimental conditions: the eye (1) prior to vitrectomy, (2) after vitrectomy, (3) after insertion of a Spectralon disk super-retinally, and (4) after subretinal insertion of the disk. The absorption of melanin and hemoglobin in the red wavelengths was used to convert relative spectral reflectance to absolute reflectance. The flux scattered from the super-retinal Spectralon was used to correct for scattering in the globe. The transmittance of the sensory retina was measured in vivo using the scatter corrected subretinal Spectralon disk reflectance. The hemoglobin and melanin components of the spectrum due to scattered light were removed from the retinal transmission spectrum. The in vivo spectral transmittance of the sensory retina in this swine was essentially flat across the visible spectrum, with an average transmittance >90%. © 2008 Society of Photo-Optical Instrumentation Engineers.
• Smith, P. K., McClain, S. C., & Chipman, R. A. (2008). Characterizing dielectric tensors with Biaxial ellipsometry. Digest of Technical Papers - SID International Symposium, 39(3), 1533-1536.
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  Abstract: Dielectric tensors of anisotropic substrates and films can be determined by biaxial ellipsometry, an extension of conventional ellipsometry. This technique utilizes an angle-of-incidence Mueller matrix imaging polarimeter. An example of the determination of the dielectric tensor of liquid crystal polymer films for retarders is presented. © 2008 SID.
• Twietmeyer, K. M., & Chipman, R. A. (2008). Optimization of Mueller matrix polarimeters in the presence of error sources. Optics Express, 16(15), 11589-11603.
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  PMID: 18648480;Abstract: Methods are presented for optimizing the design of Mueller matrix polarimeters and and in particular selecting the retardances and orientation angles of polarization components to ensure accurate reconstruction of a sample's Mueller matrix in the presence of error sources. Metrics related to the condition number and to the singular value decomposition are used to guide the design process for Mueller matrix polarimeters with the goal of specifying polarization elements, comparing polarimeter configurations, estimating polarimeter errors, and compensating for known error sources. The use of these metrics is illustrated with analyses of two example polarimeters: a dual rotating retarder polarimeter, and a dual variable retarder polarimeter. © 2008 Optical Society of America.
• Twietmeyer, K. M., Chipman, R. A., Elsner, A. E., Zhao, Y., & VanNasdale, D. (2008). Mueller matrix retinal imager with optimized polarization conditions. Optics Express, 16(26), 21339-21354.
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  PMID: 19104564;PMCID: PMC3375112;Abstract: A new Mueller matrix Polarimeter was used to image the retinas of normal subjects. Light from a linearly polarized 780 nm laser was passed through a system of variable retarders and scanned across the retina. Light returned from the eye passed through a second system of retarders and a polarizing beamsplitter to two confocal detection channels. Optimization of the Polarimetric data reduction matrix was via a condition number metric. The accuracy and repeatability of polarization parameter measurements were within ± 5%. The magnitudes and orientations of retardance and diattenuation, plus depolarization, were measured over 15° of retina for 15 normal eyes. © 2008 Optical Society of America.
• Beaudry, N. A., Zhao, Y., & Chipman, R. (2007). Dielectric tensor measurement from a single Mueller matrix image. Journal of the Optical Society of America A: Optics and Image Science, and Vision, 24(3), 814-824.
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  PMID: 17301869;Abstract: A technique for measuring dielectric tensors in anisotropic layered structures, such as thin films of biaxial materials, is demonstrated. The ellipsometric data are collected in a quasi-monochromatic Mueller matrix image acquired over a large range of incident and azimuthal angles by illuminating a very small area on the sample with a focused beam from a modulating polarization state generator. After the beam interacts with the sample, the reflected and/or transmitted light is collected using an imaging polarization state analyzer. An image of the exit pupil of a collection objective lens is formed across a CCD such that each pixel collects light from a different angle incident on the sample, thus acquiring ellipsometric data at numerous incident angles simultaneously. The large range of angles and orientations is necessary to accurately determine dielectric tensors. The small but significant polarization aberrations of the low-polarization objective lenses used to create and collect the focused beams provide a significant challenge to accurate measurement. Measurements are presented of a thin-film E-type polarizer and a stretched plastic biaxial film. © 2007 Optical Society of America.
• Chipman, R. A. (2007). Degrees of freedom in depolarizing mueller matrices. Proceedings of SPIE - The International Society for Optical Engineering, 6682.
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  Abstract: Most measured Mueller matrices tend to be slightly non physical due to noise and calibration issues.1 Based on a simple white noise model and higher dimensional geometrical considerations, only 1 out of 90 measured Mueller matrices for a non depolarizing sample should be physical, a number given by the relation ∫0π/4sin7 φ dφ/∫0πsin7 φ dφ≈0.0111 which describes the ratio of the 9-dimensional solid angle inside a 9-dimensional 45° cone to the 9-dimensional solid angle in the entire 9-dimensional hypersphere. The remaining majority of measured matrices would be expected to be slightly non physical.
• Crabtree, K., & Chipman, R. A. (2007). Subwavelength-grating-induced wavefront aberrations: A case study. Applied Optics, 46(21), 4549-4554.
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  PMID: 17609699;Abstract: The on-axis wavefront aberrations of a one-dimensional subwavelength- grating antireflection coating on an f/1.7 lens surface are shown to be small with noticeable contributions of defocus, astigmatism, and piston. The astigmatism is 0.02 wave, and the magnitude of the piston approaches one wave peak-to-valley. The difference in aberrations between orthogonally polarized wavefronts, or the retardance aberration, shows 0.01 wave of astigmatismlike variation and more than 0.01 wave of retardance-induced defocuslike variation. A small coupling between polarization states occurs in the form of the familiar Maltese cross, yielding a maximum of 3% coupling in the four diagonal edges of the pupil. © 2007 Optical Society of America.
• Denninghoff, K. R., Chipman, R. A., & Hillman, L. W. (2007). Blood oxyhemoglobin saturation measurements by blue-green spectral shift. Journal of Biomedical Optics, 12(3).
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  PMID: 17614728;Abstract: Previous work describing a resilient method for measuring oxyhemoglobin saturation using the blue-green spectral shift was performed using cell free hemoglobin solutions. Hemoglobin solution and whole blood sample spectra measured under similar conditions in a spectrophotometer are used here to begin evaluating the impact of cellular scattering on this method. The blue-green spectral shift with changing oxyhemoglobin saturation was preserved in these blood samples and the blue-green spectral shift was relatively unaffected by physiological changes in blood pH (6.6, 7.1, and 7.4), path length through blood (100 and 200 μm), and blood hematocrit (19 to 48%). The packaging of hemoglobin in red blood cells leads to a decreased apparent path length through hemoglobin, and an overall decrease in scattering loss with increasing wavelength from 450 to 850 nm. The negative slope of the scattering loss in the 476 to 516-nm range leads to a +3.0 nm shift in the oxyhemoglobin saturation calibration line when the blue-green spectral minimum in these blood samples was compared to cell free hemoglobin. Further research is needed to fully evaluate the blue green spectral shift method in cellular systems including in vivo testing. © 2007 Society of Photo-Optical Instrumentation Engineers.
• Diner, D. J., Davis, A., Hancock, B., Gutt, G., Chipman, R. A., & Cairns, B. (2007). Dual-photoelastic-modulator-based polarimetric imaging concept for aerosol remote sensing. Applied Optics, 46(35), 8428-8445.
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  PMID: 18071373;Abstract: A dual-photoelastic-modulator- (PEM-) based spectropolarimetric camera concept is presented as an approach for global aerosol monitoring from space. The most challenging performance objective is to measure degree of linear polarization (DOLP) with an uncertainty of less than 0.5% in multiple spectral bands, at moderately high spatial resolution, over a wide field of view, and for the duration of a multiyear mission. To achieve this, the tandem PEMs are operated as an electro-optic circular retardance modulator within a high-performance reflective imaging system. Operating the PEMs at slightly different resonant frequencies generates a beat signal that modulates the polarized component of the incident light at a much lower heterodyne frequency. The Stokes parameter ratio q = Q/I is obtained from measurements acquired from each pixel during a single frame, providing insensitivity to pixel responsivity drift and minimizing polarization artifacts that conventionally arise when this quantity is derived from differences in the signals from separate detectors. Similarly, u = U/I is obtained from a different pixel; q and u are then combined to form the DOLP. A detailed accuracy and tolerance analysis for this polarimeter is presented. © 2007 Optical Society of America.
• Mahler, A., & Chipman, R. (2007). Tolerancing and alignment of a three-mirror off-axis telescope. Proceedings of SPIE - The International Society for Optical Engineering, 6676.
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  Abstract: When the optical elements of a system are not collinear, there are advantages to aligning all elements simultaneously. This paper presents the steps taken to prepare for system alignment and the alignment plan for such a system. A tolerance analysis of the system defines the compensators necessary for system alignment and allows an estimate of the expected magnitude of initial aberrations present in the system. Polarization and pupil aberrations are characterized in order to further understand expected system aberrations before alignment. A two step alignment plan is outlined. First, a CCD array placed at the focal plane indicates spot size and shape as elements are aligned. Once spot size is minimized, the CCD array is replaced by a ball bearing for retroreflection. Useful interferograms can be obtained with which remaining aberrations can be minimized. This technique is presented as the alignment plan for an off-axis telescope system consisting of one spherical and two ellipsoidal mirrors.
• Mahler, A., Smith, P. K., & Chipman, R. A. (2007). Low polarization optical system design. Proceedings of SPIE - The International Society for Optical Engineering, 6682.
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  Abstract: Polarization-sensitive optical systems include those requiring very accurate irradiance measurements and those where polarization is the intended measurement. Low-polarization optical system design is the process of minimizing system polarization introduced by surface geometry, thin film coatings and birefringent elements, and measuring system components to verify polarization performance. The complicated, multi-step, iterative low polarization optical system design process requires initial system design, witness sample fabrication and measurement, reverse engineering of fabricated coatings and coating redesign, end-to-end system polarization aberration analysis, and system measurement and calibration. Most of this process will be spent iterating between design and measurement phases until a final design is reached that can be fabricated and calibrated to perform within the desired system tolerances. This work discusses low polarization optical system design using a three-mirror off-axis camera as an example.
• Noble, H., Lam, W. T., Smith, G., McClain, S., & Chipman, R. A. (2007). Polarization scattering from a Spectralon calibration sample. Proceedings of SPIE - The International Society for Optical Engineering, 6682.
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  Abstract: The in-plane Mueller matrix bidirectional reflectance distribution function (MMBRDF) is measured for a Spectralon calibration target with a reflectance of 99%. Measurements are acquired using a Mueller matrix active imaging, goniometric polarimeter operated in the near infrared at 1550nm. The Spectralon is measured for both incident and scattering angles from -80 degrees to 80 degrees to within 20 degrees of retro-reflection. A range of polarization states is generated and scattered polarization states are analyzed by means of a dual rotating retarder Mueller matrix polarimeter. Complete Mueller matrix data is measured with a high-resolution camera in image form. Polarization scatter data is presented in Mueller matrix angular arrays. As expected the Spectralon is a strong depolarizer and weak s-plane oriented diattenuator. It was also a weak retarder. Diattenuation and retardance are strongest at horizontal and vertical polarizations, and weakest for circular polarization states.
• Noble, H., Smith, G. A., Wai, S. L., McClain, S., & Chipman, R. A. (2007). Polarization imaging light scattering facility. Proceedings of SPIE - The International Society for Optical Engineering, 6682.
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  Abstract: Understanding the interaction of polarized light with materials is critical to applications such as remote sensing, laser radar, and quality control. The availability of angular and spatial information add additional dimensions to this understanding. A facility is constructed for Mueller Matrix Bidirectional Reflectance Distribution (MMBRDF) imaging. Polarized light at near infrared and visible wavelengths is scattered from samples ranging from bare metals to complex organic structures with various textures and orientations. The resulting scattered polarized light is measured with a Mueller matrix active imaging Polarimeter. The in-plane MMBRDF is measured for a sanded aluminum sample as a demonstration of the facility. The aluminum is found to be a weak depolarizer, with a somewhat higher depolarization index at specular angles. Retardance is dominated by its linear component and is close to 180° for the majority of angles. Diattenuation is weak, especially in the specular region, and increases in the region further away from specular angles.
• Smith, P. K., & Chipman, R. A. (2007). Characterizing dielectric tensors from angle-of-incidence mueller matrix images. Proceedings of SPIE - The International Society for Optical Engineering, 6682.
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  Abstract: Biaxial ellipsometry is a technique that measures the dielectric tensor and thickness of a biaxial substrate, single-layer thin film, or multi-layer structure. The dielectric tensor of a biaxial material consists of the real and imaginary parts of the three orthogonal principal indices (nx+ ikx, ny+ iky and nz + ikz) and three Euler angles (⊖, Φ Δ) to describe its orientation. The method utilized in this work measures an angle-of-incidence Mueller matrix from a Mueller matrix imaging Polarimeter equipped with a pair of microscope objectives with low polarization aberrations. The dielectric tensors for multilayer samples are determined from multi-spectral angle-of-incidence Mueller matrix images in either a transmission or reflection mode using an appropriate dispersion model. Given approximate a priori knowledge of the dielectric tensor and film thickness, a Jones matrix image is first calculated by solving Maxwell's equations at each surface which is then transformed into a Mueller matrix image. An optimization algorithm then finds the best fit dielectric tensor based on matching the measured and calculated angle-of-incidence Mueller matrix images. One use for this application is to more accurately determine the dielectric tensors of biaxial films used in liquid crystal displays.
• Yun, G., Crabtree, K., & Chipman, R. A. (2007). Properties of the polarization ray tracing matrix. Proceedings of SPIE - The International Society for Optical Engineering, 6682.
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  Abstract: The properties of a 3 × 3 polarization ray tracing matrix formalism are presented and the role of this method in optical design. Properties of diattenuator matrices are derived and methods for analyzing diattenuation of arbitrary homogeneous and inhomogeneous matrices are presented. The 3x3 matrix formalism is used to analyze polarization properties of an example corner cube.
• Crabtree, K., & Chipman, R. A. (2006). Sub-wavelength grating induced wavefront aberrations: A case study. Proceedings of SPIE - The International Society for Optical Engineering, 6342 I.
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  Abstract: The on-axis wavefront aberrations of a one-dimensional sub-wavelength grating anti-reflection coating on a f/1.7 lens surface is dominated by defocus, astigmatism, and piston. The astigmatism is 0.02 waves and the magnitude of the piston approaches 1 wave peak-to-valley. The difference in aberrations between orthogonally polarized wavefronts, or the retardance aberration, shows 0.01 waves of astigmatism like variation and more than 0.01 waves of retardance induced defocus like variation. Diffraction Gratings; Thin films, sub-wavelength Gratings © 2006 SPIE-OSA.
• Denninghoff, K. R., Chipman, R. A., & Hillman, L. W. (2006). Oxyhemoglobin saturation measurements by green spectral shift. Optics Letters, 31(7), 924-926.
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  PMID: 16599213;Abstract: From an analysis of new hemoglobin solution transmission spectra at various oxygen saturations (SO2), path lengths, and pH, we find the determination of SO2 by using the classical oximetry technique to be poorly calibrated. We used this data set to develop a proposed method for SO2 determination based on the spectral shift of the hemoglobin transmission minimum between 475 and 510 nm. The method does not require accurate knowledge of hemoglobin extinction coefficients and is linear in relation to SO2 despite changes in path length, pH, or hemoglobin concentration. © 2006 Optical Society of America.
• Salyer, D., Beaudry, N., Basavanthappa, S., Twietmeyer, K., Eskandari, M., Denninghoff, K., Chipman, R., & Park, R. (2006). Retinal oximetry using intravitreal illumination. Current Eye Research, 31(7-8), 617-627.
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  PMID: 16877270;Abstract: Purpose: To demonstrate spectroscopic retinal oximetry measurements on arteries and veins in swine using intravitreal illumination. Retinal arterial and venous saturations are measured for a range of inspired O 2 levels after pars plana vitrectomy. Methods: Pars plana vitrectomy and intravitreal manipulations were performed on two female American Yorkshire domestic swine. Light from a scanning monochromator was coupled into a fiberoptic intraocular illuminator inserted into the vitreous. The retinal vessels were illuminated obliquely, minimizing vessel glints. Multispectral images of the retinal vasculature were obtained as the swine's arterial blood oxygen saturation was decreased from 100% to 67% in decrements of approximately 10%. Retinal vessel spectra were used to calculate oxygen saturation in selected arteries and veins. Arterial oxygen saturations were calibrated using blood gas analysis on blood drawn from a Swan-Ganz catheter placed in the femoral artery. Results: Oblique illumination of retinal vessels using an intravitreal fiberoptic illuminator provided a substantial reduction in the central vessel glint usually seen in fundus images, thus simplifying the analysis of spectral data. The vessel shadows were displaced from the vessel image simplifying the light paths in the eye. Using a full spectral analysis simplified by the light path reductions, we calculated retinal vessel saturations. The reduction of glint allowed for increased accuracy in measuring retinal vessel spectral optical density. Abnormally low retinal venous oxygen saturations were observed shortly after pars plana vitrectomy. Conclusions: Retinal oximetry using intravitreal illumination has been demonstrated. As a research tool, intravitreal illumination addresses several difficulties encountered when performing retinal oximetry with transcorneal illumination. Copyright © Informa Healthcare.
• Venkatasubbarao, S., Beaudry, N., Zhao, Y., & Chipman, R. (2006). Evanescent-imaging-ellipsometry-based microarray reader. Journal of Biomedical Optics, 11(1).
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  PMID: 16526905;Abstract: We describe the development of a label-less ellipsometric imaging microarray reader. The ability of the ellipsometric microarray reader to measure binding of sample to microarray surface is verified using oligonucleotide complementary DNA (cDNA) microarrays. Polarized light illuminates the microarray surface through a glass substrate at an angle beyond the critical angle and changes in the polarization of totally internally reflected light resulting from binding events on the microarray surface are measured. This polarization change is used to measure the thickness of biomolecules bound to the microarray. A prototype ellipsometric imaging microarray reader is constructed and calibrated, and the performance is evaluated with cDNA microarrays. The microarray reader measures changes in refractive index changes as small as 0.0024 and thickness changes as small as 0.28 nm. The optimization of angle of incidence and substrate refractive index necessary to achieve high sensitivity is also described. This ellipsometric technique offers an attractive alternative to fluorescence-microarray readers in some genomic, proteomic, diagnostic, and sensing applications. © 2006 Society of Photo-Optical Instrumentation Engineers.
• Wolfe, J. E., & Chipman, R. A. (2006). Polarimetric characterization of liquid-crystal-on-silicon panels. Applied Optics, 45(8), 1688-1703.
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  PMID: 16572683;Abstract: Mueller matrix imaging polarimetry of liquid-crystal-on-silicon (LCoS) panels provides detailed information useful for the diagnosis of LCoS problems and to understand the interaction of LCoS panels with other projector components. Data reduction methods are presented for the analysis of LCoS Mueller matrix images yielding contrast ratio, efficiency, spatial uniformity, and the calculation of optimum trim retarders. The effects of nonideal retardance, retardance orientation, and depolarization on LCoS system performance are described. The white-state and dark-state Mueller matrix images of an example LCoS panel are analyzed in terms of LCoS performance metrics typical for red-green-blue wavelengths of 470, 550, and 640 nm. Variations of retardance, retardance orientation, and depolarization are shown to have different effects on contrast ratio, efficiency, and brightness. Thus Mueller matrix images can diagnose LCoS problems in a way different from radiometric testing. The calculation of optimum trim retarders in the presence of spatial variations is discussed. The relationship of the LCoS retardance in single-pass (from front to back) to the double-pass retardance (from entrance to exit) is established and used to clarify coordinate system issues related to Mueller matrices for reflection devices. © 2006 Optical Society of America.
• Beaudry, N. A., Zhao, Y., & Chipman, R. (2005). Multi-angle generalized ellipsometry of anisotropic optical structures. Proceedings of SPIE - The International Society for Optical Engineering, 5888, 1-11.
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  Abstract: A new technique for simultaneous multi-angle ellipsometric measurements of anisotropic optical structures such as films used in the display industry is introduced. A very small area on the sample is illuminated with a focused beam which after it interacts with the sample and is polarization analyzed is spread across a CCD. Each pixed collects light from a different angle incident on the sample allowing data collection at numerous incident angles simultaneously. The small but significant polarization aberrations of the microscope objectives provide a significant challenge to accurate measurement A mathematical description of the ellipsometric technique is presented. The optical properties of two biaxial samples, a stretched plastic retarder element used for correcting angle of incident effects in LC displays, and a thin layer of E-type polarizing dried liquid crystal material are measured and maps of the ellipsometric parameters ψ and Δ as a function incident and azimuthal angles are presented. Data from both samples are reduced using an iterative algorithm with a biaxial thin film modeling software package to compute all three principle components of the dielectric tensor as well as it's orientation.
• Chipman, R. A. (2005). Biaxial ellipsometry. Proceedings of SPIE - The International Society for Optical Engineering, 5875, 1-8.
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  Abstract: Biaxial ellipsometry measures the optical constants of materials, anisotropic films, and stacks of anistropic films. Materials of interest include birefringent crystals, polarizing materials and films, and the complex multilayer anisotropic structures used in liquid crystal displays. An approach using Mueller matrix imaging polarimetry to simultaneously measure and angularly resolve reflection and transmission over large solid angles is presented. Biaxial materials have three refractive indices and three absorption coefficients in orthogonal directions but with arbitrary orientation. Determination of the dielectric tensor provides a succinct and suitable material representation, and its accurate determination is the focus of this investigation.
• Chipman, R. A. (2005). Depolarization index and the average degree of polarization. Applied Optics, 44(13), 2490-2495.
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  PMID: 15881055;Abstract: Two single number metrics for depolarization of samples are contrasted: (1) the average degree of polarization of the exiting light averaged over the Poincaré sphere and (2) the depolarization index of Gill and Berhenau [Opt. Acta 32, 259-261 (1985); 33, 185-189 (1986)]. The depolarization index is a geometric measure that varies from 0 for the ideal depolarizer to 1 for nondepolarizing Mueller matrices. The average degree of polarization also varies from 0 to 1 and characterizes the typical level of depolarization. Although the depolarization index is very often close to the average degree of polarization, these two metrics can differ by more than 0.5 for certain Mueller matrices. © 2005 Optical Society of America.
• Chipman, R. A. (2005). Metrics for depolarization. Proceedings of SPIE - The International Society for Optical Engineering, 5888, 1-10.
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  Abstract: Several single-valued metrics have been introduced for the assessment of depolarization including the Depolarization Index and the Average Degree of Polarization (obtained by averaging the exiting degree of polarization over all incident polarization states). These metrics are compared then a more complete representation of depolarization is introduced, the Degree of Polarization Surfaces, which help elucidate the structure of the depolarization degrees of freedom within the Mueller calculus.
• Chipman, R. A., & Wolfe, J. (2005). Reducing symmetric polarization aberrations in a molded glass lens by annealing. Proceedings of SPIE - The International Society for Optical Engineering, 5888, 1-8.
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  Abstract: Mueller matrix imaging polarimetry was used to study stress in a series of a high numerical aperture molded glass lenses. An interesting radially symmetric retardance was found which resembled the polarization aberration induced by coatings. Upon investigation the source of the polarization aberration is traced to a remarkably symmetric radial stress birefringence in the glass believed to arise during fire-polishing of the surfaces. While annealing the lenses relieves much of the stress birefringence, reducing the retardance of the lenses by a factor of five, the lenses remained unusable for critical polarization applications.
• Crabtree, K., Beaudry, N., & Chipman, R. (2005). Off-resonance properties of a photoelastic modulator. Proceedings of SPIE - The International Society for Optical Engineering, 5888, 1-6.
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  Abstract: Polarization modulation in photo-elastic modulators (PEM) driven on and off resonance has been investigated for a commercially available PEM using a high speed infrared (lambda=1550 nm) polarimeter. Off-resonance operation was explored in the hope of finding a slower operating mode than the primary resonance. The primary resonance, used for normal PEM operation, was 5 Hz wide with a Q of 8500. The phase transfer function was well behaved and typical of electrical resonances. Device startup and shutdown had smooth amplitude changes occurring over 1/3 rd of a second. The photo-elastic modulator was examined at drive frequencies significantly below the resonant frequency. Driving the PEM with several odd sub-harmonics generated resonance at the fundamental frequency. Three other lower frequency resonances were discovered, but all at an oscillation amplitude more than 12 db below the amplitude of the fundamental resonance. Thus a practical configuration to allow slower operation of the PEM was not found.
• Diner, D. J., Chipman, R. A., Beaudry, N., Cairns, B., Foo, L. D., Macenka, S. A., Cunningham, T. J., Seshadri, S., & Keller, C. (2005). An integrated multiangle, multispectral, and polarimetric imaging concept for aerosol remote sensing from space. Proceedings of SPIE - The International Society for Optical Engineering, 5659, 88-96.
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  Abstract: Techniques for passive remote sensing of aerosol optical and microphysical properties from space include visible, near-and shortwave-infrared imaging (e.g., from MODIS), multiangle intensity imaging (e.g., ATSR-2, AATSR, MISR), near-ultraviolet mapping (e.g., TOMS/OMI), and polarimetry (e.g., POLDER, APS). Each of these methods has unique strengths. In this paper, we present a concept for integrating these approaches into a unified sensor. Design goals include spectral coverage from the near-UV to the shortwave infrared; intensity and polarimetric imaging simultaneously at multiple view angles; global coverage within a few days; kilometer to sub-kilometer spatial resolution; and measurement of the degree of linear polarization (DOLP) for a subset of the spectral complement with an uncertainty of 0.5% or less. This high polarimetric accuracy is the most challenging aspect of the design, and is specified in order to achieve climate-quality uncertainties in optical depth, refractive index, and other microphysical properties. Based upon MISR heritage, a pushbroom multi-camera architecture is envisioned, using separate line arrays to collect imagery within each camera in the different spectral bands and in different polarization orientations. For the polarimetric data, accurate cross-calibration of the individual line arrays is essential. An electro-optic polarization "scrambler", activated periodically during calibration sequences, is proposed as a means of providing this cross-calibration. The enabling component is a rapid retardance modulator. Candidate technologies include liquid crystals, rotating waveplates, and photoelastic modulators (PEMs). The PEM, which uses a piezoelectric transducer to induce rapid time-varying stress birefringence in a glass bar, appears to be the most suitable approach. An alternative measurement approach, also making use of a PEM, involves synchronous demodulation of the oscillating signal to reconstruct the polarization state. The latter method is potentially more accurate, but requires a significantly more complex detector architecture.
• Park, R., Twietmeyer, K., Chipman, R., Beaudry, N., & Salyer, D. (2005). Wavelength dependence of the apparent diameter of retinal blood vessels. Applied Optics, 44(10), 1831-1837.
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  PMID: 15813519;Abstract: Imaging of retinal blood vessels may assist in the diagnosis and monitoring of diseases such as glaucoma, diabetic retinopathy, and hypertension. However, close examination reveals that the contrast and apparent diameter of vessels are dependent on the wavelength of the illuminating light. In this study multispectral images of large arteries and veins within enucleated swine eyes are obtained with a modified fundus camera by use of intravitreal illumination. The diameters of selected vessels are measured as a function of wavelength by cross-sectional analysis. A fixed scale with spectrally independent dimension is placed above the retina to isolate the chromatic effects of the imaging system and eye. Significant apparent differences between arterial and venous diameters are found, with larger diameters observed at shorter wavelengths. These differences are due primarily to spectral absorption in the cylindrical blood column. © 2005 Optical Society of America.
• Salyer, D. A., Twietmeyer, K., Beaudry, N., Basavanthappa, S., Park, R. I., & Chipman, R. (2005). In vitro multispectral diffuse reflectance measurements of the porcine fundus. Investigative Ophthalmology and Visual Science, 46(6), 2120-2124.
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  PMID: 15914632;Abstract: PURPOSE. To quantify the reflectance of the swine fundus as a function of illumination angle and wavelength using a novel technique of intravitreal illumination. METHODS. Enucleated swine eyes were illuminated with a scanning monochromator coupled to a fiber-optic probe placed in the vitreous at several locations. Intravitreal illumination was used to reduce the effects of extraneous reflections and scatter from the anterior structures of the eye, including glints from the internal limiting membrane and blood vessels. Intravitreal illumination provided different light paths and additional information to apply to retinal reflectance modeling. A 25-mm2 region of the illuminated fundus was imaged while the angle of illumination was varied over a maximum range of 22°. Multispectral images from areas free of large blood vessels were acquired. The diffusely reflected intensity was integrated over the pupil with a solid angle of 0.028 steradians. The spectral reflectance function was calculated for multiple illumination angles. RESULTS. Multispectral fundus image sets were obtained for two enucleated swine eyes by using intravitreal illumination. The fundus spectral reflectance function showed decreasing reflectance with increasing illumination angle, rapid changes in the 430- to 480-nm range, and a fairly consistent reflectance decrease for 480 to 700 nm. CONCLUSIONS. Variations in fundus spectral reflectance with change in the illumination angle were found to deviate from Lambertian behavior, varying from Lambertian by 5% across the spectrum in one sample and 20% in a second sample. Intravitreal illumination resulted in markedly decreased extraneous reflections. Copyright © Association for Research in Vision and Ophthalmology.
• Chipman, R. A., & Kinnera, R. (2004). First- and second-order polarization mode dispersion generated by a two-stage emulator. Applied Optics, 43(33), 6074-6079.
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  PMID: 15605546;Abstract: A two-stage polarization mode dispersion (PMD) emulator design consisting of two variable delay lines separated by a rotatable half-wave linear retarder is analyzed and shown to generate an adjustable amount of first- and second-order PMD without any higher orders. This two-stage PMD emulator configuration provides a simple easy-to-breadboard solution for second-order PMD emulators. When compared with PMD emulators based on birefringent crystals, this two-stage emulator is simpler to calibrate. © 2004 Optical Society of America.
• DeBoo, B., & Chipman, R. A. (2004). Polarization scatter measurements with a Mueller matrix imaging polarimeter. Proceedings of SPIE - The International Society for Optical Engineering, 5526, 176-187.
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  Abstract: A Mueller matrix imaging polarimeter is used to acquire polarization-sensitive images of seven different manmade samples in multiple scattering geometries. Successive Mueller matrix images of a sample with changing incidence and scatter angles are used to develop a Mueller matrix bidirectional reflectance distribution function for the sample in one plane of measurement. The Mueller matrix bidirectional reflectance distribution functions are compared, and patterns are noted. The most significant data for the scattering samples measured occurs along the diagonal of the respective Mueller matrices, indicating significant depolarization effects. Reduced depolarization data in the form of the average degree of polarization (of exiting light) for each sample is examined as a function of changing scattering geometry. Five of seven manmade samples exhibit an inverted Gaussian profile of depolarization with changing scattering geometry, the shape of which may prove useful for measuring sample properties (e.g. roughness) and for classifying or categorizing samples in a remote sensing scheme. Depolarization differences for each sample in response to changing incident polarization states are also examined, and a new metric, the degree of polarization surface, has been developed to visualize all such data simultaneously.
• Diner, D. J., Macenka, S. A., Bruce, C. F., Seshadri, S., Jau, B., Chipman, R. A., Cairns, B., Keller, C., & Foo, L. D. (2004). Enabling technologies for high-accuracy multiangle spectropolarimetric imaging from space. A Collection of Technical Papers - AIAA Space 2004 Conference and Exposition, 2, 1092-1098.
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  Abstract: Satellite remote sensing plays a major role in measuring the optical and radiative properties, environmental impact, and spatial and temporal distribution of tropospheric aerosols. In this paper, we envision a new generation of spaceborne imager that integrates the unique strengths of multispectral, multiangle, and polarimetric approaches, thereby achieving better accuracies in aerosol optical depth and particle properties than can be achieved using any one method by itself. Design goals include spectral coverage from the near-UV to the shortwave infrared; global coverage within a few days; intensity and polarimetric imaging simultaneously at multiple view angles; kilometer to sub-kilometer spatial resolution; and measurement of the degree of linear polarization for a subset of the spectral complement with an uncertainty of 0.5% or less. The latter requirement is technically the most challenging. In particular, an approach for dealing with inter-detector gain variations is essential to avoid false polarization signals. We propose using rapid modulation of the input polarization state to overcome this problem, using a high-speed variable retarder in the camera design. Technologies for rapid retardance modulation include mechanically rotating retarders, liquid crystals, and photoelastic modulators (PEMs). We conclude that the latter are the most suitable. Two approaches for using a PEM to achieve high polarimetric accuracy are presented. In the first approach, amplitude modulation, the device is used intermittently to modify the incoming polarization state so that different detectors-those with polarizing filters in different orientations-can be accurately cross-calibrated. In the other approach, synchronous demodulation, signals accumulated during sub-cycles of the modulation are sorted and stored using a high-speed electronic charge-caching circuit built into the detector array. Copyright © 2004 by the American Institute of Aeronautics and Astronautics, Inc.
• Venkatasubbarao, S., Beaudry, N., Zhao, Y., & Chipman, R. (2004). Evanescent imaging ellipsometry based microarray readers. Proceedings of SPIE - The International Society for Optical Engineering, 5586, 1-12.
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  Abstract: Microarrays are being widely used in genomic, proteomic, and diagnostic applications. The binding events to the microarrays are measured with fluorescent labels. Fluorescent microarray readers offer high sensitivity and normalization of the reference and test samples. The use of labels increases the number of steps involved in array testing, concerns about storage labels, and cost of additional labeling steps. This paper describes an alternative approach that does not require the use of fluorescent or other labels. The binding events on the microarray introduce changes in polarization of the illuminated light which is measured to determine the concentrations of biomolecules bound to the microarray. Oligonucleotide microarrays were synthesized and tested on the imaging microarray reader. The refractive index changes of 0.006 and changes in thickness of 1 nm are demonstrated at a spatial resolution of 20 μm over a field of view of 1 cm 2. This ellipsometric technique offers an attractive alternative to fluorescence-based measurement and could be very valuable in some of the genomic, proteomic, diagnostic, and sensing applications.
• Wolfe, J., & Chipman, R. A. (2004). Reducing symmetric polarization aberrations in a lens by annealing. Optics Express, 12(15), 3443-3451.
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  PMID: 19483870;Abstract: Radially symmetric retardance was found in antireflection coated, molded aspheric glass lenses by measurement with a Mueller matrix imaging polarimeter. The source of the unexpected polarization aberration is traced to a remarkably symmetric radial stress birefringence in the glass believed to arise during fire-polishing of the surfaces. While annealing the lenses relieves much of the stress birefringence, reducing the retardance of the lenses by a factor of five, the lenses remained unusable. © 2004 Optical Society of America.
• Chipman, R. A. (2003). Advances in Polarization Metrology. Proceedings of SPIE - The International Society for Optical Engineering, 5174, 43-50.
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  Abstract: Three new polarimeters are described which represent advances in polarization metrology capabilities. Two are at a new polarization laboratory started at the University of Arizona's Optical Sciences Center, (1) a Fiber Optic Spectropolarimeter and (2) a High Speed Mueller Matrix Imaging Polarimeter. The third is a new visible Mueller Matrix Spectropolarimeter for optical component test from a startup company, Axometrics, which is useful for detailed characterization of optical components and thin films via spectra of diattenuation, retardance, and depolarization.
• Chipman, R. A. (2003). Depolarization in the Mueller Calculus. Proceedings of SPIE - The International Society for Optical Engineering, 5158, 184-192.
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  Abstract: Depolarization is the generation of partially polarized light or unpolarized light from a completely polarized incident beam. For example when polarized light scatters from rough surfaces, the degree of polarization is usually reduced from one. Depolarization figures of merit are discussed and difficulties with the depolarization index are highlighted. Interesting depolarization patterns are presented for a liquid crystal in reflection are measured with a commercial polarimeter. Depolarization data from rough metal surfaces and paint is also discussed.
• Martinelli, M., & Chipman, R. A. (2003). Endless Polarization Control Algorithm Using Adjustable Linear Retarders With Fixed Axes. Journal of Lightwave Technology, 21(9), 2089-2096.
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  Abstract: New designs are presented for polarization-transforming elements equivalent to rotating quarter-wave plates and rotating half-wave plates. These are constructed from sequences of adjustable linear retarders with fixed retardation axes, such as liquid-crystal cells (untwisted nematic) and electrooptical modulators. Then, a new endless polarization control algorithm is proposed and demonstrated. The variable linear retarders in this endless polarization controller operate over a finite range of retardance without any reset or unwinding procedure. This endless algorithm can produce all possible sequences of continuous polarization state transformations.
• Wolfe, J., & Chipman, R. (2003). Characterization of Polarization Aberrations in Liquid Crystal Devices. Proceedings of SPIE - The International Society for Optical Engineering, 5188, 1-5.
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  Abstract: Reflective Liquid Crystal on Silicon (LCoS) panels are widely used as light valves for projection displays. LCoS panels and the associated beam splitters, retardance films, and dichroic beam splitters display significant variations in polarization properties over the area, angle of incidence and spectral bandwidth of the projector. This paper surveys these polarization aberrations and describes a high speed Mueller Matrix Imaging Polarimeter (MMIP) for the characterization of these polarization aberrations. The characterization of projection systems and components by the MMIP enables advanced modeling and compensation of polarization aberrations.
• Wolfe, J., & Chipman, R. (2003). High Speed Imaging Polarimeter. Proceedings of SPIE - The International Society for Optical Engineering, 5158, 24-32.
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  Abstract: A high speed Mueller matrix imaging polarimeter is presented. The instrument enables measurement of the full Mueller matrix in transmission, reflection, or retro-reflection. The Mueller matrix provides a complete description of the polarization transforming properties of the sample. The retardance, diattenuation, polarizance, and depolarization are all characterized by the polarimeter. The polarimeter is able to measure the polarization properties of samples ranging from sub-millimeter optical components to large optics. The imaging capabilities can be modified to measure the polarization properties across the surface of the sample or as a function of the angle through the sample. The dual rotating retarder polarimeter provides up to sixty-two full Mueller matrix images per second. Instrument details, measurement techniques, example data, and applications are presented.
• Chipman, R. A. (2002). Polarization issues in fiber systems. Proceedings of SPIE - The International Society for Optical Engineering, 4481, 81-86.
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  Abstract: Polarization issues drive the design of fiber optic communications systems. The polarization properties, polarization dependent loss (PDL), retardance, polarization mode dispersion (PMD), and depolarization of many fiber system components must be controlled to tight specifications. This demand for tight component quality is leading to new generations of improved polarization measurement systems for fiber optics. Because of the complexity of polarization properties and their interaction in fiber systems, Mueller matrix measurements are recommended for those components, such as thin films and polarization controllers, which have combinations of polarization mode dispersion and polarization dependent loss.
• Chipman, R., & Kinnera, R. (2002). High-order polarization mode dispersion emulator. Optical Engineering, 41(5), 932-937.
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  Abstract: A system for generating polarization mode dispersion is developed to reproduce a close approximation to the polarization mode dispersion (PMD) of fiber links in the laboratory. A multistage system of rotating wave plates and combinations of birefringent elements generates a mixture of first-order, second-order, and higher order PMD suitable for testing OC-192 and OC-768 hardware. The PMD emulator can be operated in either static or time-varying modes. In the static mode, first-order PMD is generated with the differential group delay (DGD) continuously adjustable from 0 to 160 ps. In the dynamic mode, time-varying PMD containing first and higher orders is generated with an approximately Maxwellian DGD distribution. The PMD emulator generates PMD variations at adjustable frequencies up to 400 Hz.
• DeSalvo, R., Wilson, A. G., Rollman, J., Schneider, D. F., Lunardi, L. M., Lumish, S., Agrawal, N., Steinbach, A. H., Baun, W., Wall, T., Ben-Michael, R., Itzler, M. A., Fejzuli, A., Chipman, R. A., Kiehne, G. T., & Kissa, K. M. (2002). Advanced components and sub-system solutions for 40 Gb/s transmission. Journal of Lightwave Technology, 20(12), 2154-2181.
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  Abstract: With the commissioning of the latest 10-Gb/s systems, vendors are now in the process of developing architectures for their next-generation products. 40-Gb/s components and subsystems are currently in development to address the necessities of these next-generation systems. The top three challenges associated with 40-Gb/s transmission are optical signal-to-noise ratio, dispersion, and high-speed components. In order to realize 40-Gb/s transmission, new component and subsystem developments are crucial. This paper reviews the latest transmission technologies and dispersion compensation techniques developed to fulfill 40-Gb/s transmission system requirements.
• Smith, M. H., & Chipman, R. A. (2002). Comparison of different PMD compensator configurations based on outage probability. Conference on Optical Fiber Communication, Technical Digest Series, 70, 233-234.
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  Abstract: The comparison of different polarization mode dispersion (PMD) compensator configurations was done based on outage probability. Each of the configurations performed an all-optical compensation and used the degree of polarization (DOP) of the compensated signal as a feedback parameter. The uncompensated and compensated bit error rate (BER) for each of the PMD compensator configuration was also plotted.
• Hadaway, J. B., Ahmad, A., Pezzaniti, J. L., Chipman, R. A., Wilkes, D. R., Hummer, L. L., Crandall, D. G., & Bennett, J. M. (2001). Real-time total integrated scattering measurements on the Mir spacecraft to evaluate sample degradation in space. Applied Optics, 40(16), 2755-2768.
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  PMID: 18357293;Abstract: An instrument to measure total integrated scattering (TIS) in space was built as part of the Optical Properties Monitor instrument package and flown on the Russian Mir Space Station in a low Earth orbit. TIS at two wavelengths was measured in space at approximately weekly intervals from 29 April to 26 December 1997 and telemetered to Earth during the mission. Of the 20 TIS samples, 13 are described here to illustrate the performance of the TIS instrument. These include ten optical samples and three thermal control samples. Two optical samples and one thermal control sample were severely degraded by atomic oxygen. All samples received a light dusting of particles during the mission and an additional heavier layer after the samples returned to Earth. The initial brassboard instrument and the validation tests of the flight instrument are also described. © 2001 Optical Society of America.
• Chipman, R. A. (2000). Structure of the Mueller calculus. Proceedings of SPIE - The International Society for Optical Engineering, 4133, 1-9.
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  Abstract: The sixteen elements of the Mueller matrix are associated with sixteen degrees of freedom, seven nonpolarizing, and nine depolarizing degrees of freedom. Combinations of polarization elements are associated with all the degrees of freedom demonstrating that physically realizable polarization elements span all sixteen degrees. Two alternative polarization basis states are introduced.
• Chipman, R. A. (1999). Depolarization. Proceedings of SPIE - The International Society for Optical Engineering, 3754, 14-20.
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  Abstract: Depolarization is the reduction in degree of polarization which occurs when a light beam interacts with surfaces or optical elements. Depolarization is a scrambling of polarization states. The depolarization of Mueller matrices is studied here by mapping the resultant degree of depolarization for all possible polarized incident states (over the surface of the Poincare sphere). Example Mueller matrices are constructed with a variety of different depolarization properties to demonstrate the different depolarization degrees of freedom. These properties can then be applied to understand measurements of depolarization. A classification is presented where depolarization is considered as occurring before diattenuation, in series with diattenuation, or following diattenuation.
• Gerligand, P., Smith, M. H., & Chipman, R. A. (1999). Polarimetric images of a cone. Optics Express, 4(10), 420-430.
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  PMID: 19396298;Abstract: Scenes from a Mueller matrix movie of a brass cone are shown. From the Mueller matrix image, a variety of polarization measures are calculated and displayed. These polarization images reveal considerable details about the geometry of the cone despite the fact that the images are taken from a single vantage point, i. e. they are "flat images". As the cone rotates, the orientation of the diattenuation and retardance follow the shape of the cone, providing a clear indication of its shape. © 1999 Optical Society of America.
• Lamb, D. J., Chipman, R. A., Dimmock, J. O., Hillman, L. W., & Takahashi, Y. (1998). AIRWATCH: The collection optics. Proceedings of SPIE - The International Society for Optical Engineering, 3445, 494-504.
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  Abstract: The Airwatch optical system is shown to have minimal resolution requirements (when compared to more standard imaging systems) while requiring both a large entrance aperture and a simple configuration. Several single and double element optical systems are discussed, and Fresnel lenses are shown to be a promising candidate for the Airwatch optical system. Design techniques of Fresnel lens systems are presented, and it is shown how complex Fresnel lenses systems can be modeled and analyzed using commercially available ray tracing programs. It is then demonstrated how the performance of the single element system can be improved through the use of a two element configuration. Specifically, focal surface curvature can be eliminated, and the field of view of a single aperture can be increased by switching to the two element design. Techniques for reducing the size of the focal surface are also discussed. Finally, current research efforts involving the construction of prototype Fresnel lens systems are explained.
• Lu, S., & Chipman, R. A. (1998). Mueller matrices and the degree of polarization. Optics Communications, 146(1-6), 11-14.
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  Abstract: This article shows that only polarizers, retarders, and improper rotation Mueller matrices do not decrease the degree of polarization for any input Stokes vector. On the other hand, a Mueller matrix does not increase the degree of polarization for any input Stokes vector if and only if it has an unpolarized Stokes vector as eigenvector. Furthermore, for any Mueller matrix an unpolarized incident Stokes vector always has the maximum gain in the degree of polarization. It is pointed out that a general Mueller matrix deforms the Poincaré sphere (for input Stokes vectors) into an ellipsoid (for output Stokes vectors). Finally, several inequalities involving the input and output degrees of polarization are derived. © 1998 Published by Elsevier Science B.V.
• Smith, M. H., R.deiminghoff, K., Hillman, L. W., & Chipman, R. A. (1998). Oxygen saturation measurements of blood in retinal vessels during blood loss. Journal of Biomedical Optics, 3(3), 296-303.
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  PMID: 23015083;Abstract: We describe a noninvasive technique and instrumentation for measuring the oxygen saturation of blood in retinal arteries and veins. The measurements are made by shining low-power lasers into the eye, and scanning the beams across a retinal blood vessel. The light reflected and scattered back out of the eye is collected and measured. The oxygen saturation of blood within the vessel is determined by analyzing the vessel absorption profiles at two wavelengths. A complete saturation measurement can be made in less than 1 s, allowing real-time measurement during physiologic changes. The sensitivity of this measurement technique to changes in retinal saturation has been demonstrated through a series of pilot studies in anesthetized swine. We present data indicating that retinal venous oxygen saturation decreases during ongoing blood loss, demonstrating a potential application of an eye oximeter to noninvasively monitor blood loss. © 1998 Society of Photo-Optical Instrumentation Engineers.
• Chipman, R. A. (1997). Polarization Diversity Active Imaging. Proceedings of SPIE - The International Society for Optical Engineering, 3170, 68-73.
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  Abstract: Polarization Diversity Active Imaging is a new active imaging technique which illuminates a scene or target with a sequence of polarization states and then measures images of the polarization state scattered from a scene. These polarization images are then analyzed to determine the polarization characteristics at each pixel by measuring the Mueller matrix image, then mapping the retardance, diattenuation, and depolarization images over the scene. These data sets are used to estimate the plane of incidence and target orientation pixel by pixel.
• Chipman, R. A., & Lu, S. (1997). Decomposition of Mueller matrices. Proceedings of SPIE - The International Society for Optical Engineering, 3120, 385-396.
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  Abstract: We present an algorithm which decomposes a Mueller matrix into a sequence of three matrix factors: a diattenuator, followed by a retarder, then followed by a depolarizer. Those factors are unique except for singular Mueller matrices. Based upon this decomposition, the diattenuation and retardance of a Mueller matrix can be defined and computed. Thus, this algorithm is useful for performing data reduction upon experimentally determined Mueller matrices. ©2004 Copyright SPIE - The International Society for Optical Engineering.
• Denninghoff, K. R., Smith, M. H., Chipman, R. A., Hillman, L. W., Jester, P. M., Hughes, C. E., Kuhn, F., & Rue, L. W. (1997). Retinal large vessel oxygen saturations correlate with early blood loss and hypoxia in anesthetized swine. Journal of Trauma - Injury, Infection and Critical Care, 43(1), 29-34.
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  PMID: 9253904;Abstract: Background: Noninvasive monitoring would likely improve trauma care. Using laser technology, we monitored the oxygen saturation in retinal vessels during exsanguination and hypoxia. Methods: Seven anesthetized swine were bled at 0.4 mL/kg/min for 40 minutes. During exsanguination, retinal venous saturation (S(rv)O2) was measured using an eye oximeter, and central venous saturation (S(v)O2) was measured using a fiber-optic catheter. After the shed blood was reinfused, the FiO2 was progressively decreased from 0.97 to 0.07. Femoral artery oxygen saturation (S(a)O2) and retinal artery oxygen saturation (S(ra)O2) were measured at each increment. Results: During exsanguination, S(rv)O2 correlated with blood loss (r = -0.93) and S(v)O2 (r = 0.94). S(ra)O2 correlated with S(a)O2 during incremental hypoxia (R2 = 0.93 ± 0.15). Conclusions: In this model of exsanguination, retinal venous oxygen saturation correlates with blood volume and with central venous oxygen saturation. The S(ra)o2 correlates with S(a)O2 during graded hypoxia. Use of an eye oximeter to noninvasively monitor trauma patients appears promising and warrants further study.
• Drewes, J. J., Chipman, R. A., Hadaway, J. B., & Ahmad, A. (1997). Automated MTF analyzer for spectacle lenses. Proceedings of SPIE - The International Society for Optical Engineering, 3134, 122-135.
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  Abstract: An optical testing instrument, the Eyeglass Image Quality Mapper, has been developed that maps the power, astigmatism, and modulation transfer function over the surface of a progressive addition eyeglass lens. This instrument models the manner in which the eye views different regions of the lens and is automated so that testing can be performed without supervision and in a reasonable amount of time.In this paper, we describe the concept development, final design, and use of the instrument. ©2004 Copyright SPIE - The International Society for Optical Engineering.
• Gerligand, P., Chipman, R. A., Sornsin, E. A., & Smith, M. H. (1997). Polarization signatures of spherical and conical targets measured by Mueller matrix imaging polarimetry. Proceedings of SPIE - The International Society for Optical Engineering, 3121, 63-73.
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  Abstract: The polarization and depolarization properties of two types of targets (spherical and conical targets) have been derived from the experimental determination of their Muller matrix image. Each polarization signature is deduced from the polar decomposition of the Mueller matrix into images of retardance, diattenuation, polarizance, and depolarization. Different correlations between the polarization parameters and synthesized angle of incidence and angle of scatter images have been developed to determine an approximation of the angle of incidence from the polarization signatures.
• Goldstein, D. H., & Chipman, R. A. (1997). Erratum: Polarization: Measurment, analysis, and remote sensing (30 July - 1 August 1997). Proceedings of SPIE - The International Society for Optical Engineering, 3121, 476-477.
• Goldstein, D. H., & Chipman, R. A. (1997). Proceedings of SPIE - The International Society for Optical Engineering: Introduction. Proceedings of SPIE - The International Society for Optical Engineering, 3121, ix.
• Lompado, A., Sornsin, E. A., & Chipman, R. A. (1997). HN22 sheet polarizer, an inexpensive infrared retarder. Applied Optics, 36(22), 5396-5402.
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  PMID: 18259360;Abstract: The popular sheet polarizer, Polaroid HN22, has been measured to be a nearly half-wave retarder in the 3.6-5.4-μm spectral band with a transmittance of approximately 20%. Tuning of the retardance value between 60° and 260° has been demonstrated by tilting of the HN22 sheet with respect to the incident beam. The material's availability, relatively large aperture, large field of view, and low cost make it an excellent candidate for use as an infrared retarder for systems operating in this wave band. Thus HN22 may be employed as an inexpensive half-wave linear retarder and used for rotating the plane of polarization as well as for conversion between circular polarization states. © 1997 Optical Society of America.
• Lompado, A., Sornsin, E. A., & Chipman, R. A. (1997). Near-achromatic retardance behavior of HN22 Polaroid 3.6 - 5.4 microns. Proceedings of SPIE - The International Society for Optical Engineering, 3121, 193-202.
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  Abstract: Polaroid HN22, a popular sheet polarizer, has been measured to be a nearly half wave retarder in the 3.6 to 5.4 μ m spectral band with a transmittance of approximately 20%. The exact retardance value may be tuned to the range of 60° - 260° by tilting the HN22 with respect to the incident beam. The material's polarizing effects have been shown to be minimal in this waveband. Its availability, relatively large available aperture, large field of view, and low cost make HN22 an excellent candidate for use as an infrared retarder for systems operating from 3.6 to 5.4 μ m. As such, HN22 may be used for rotating the plane of polarization of an incident linearly polarized beam as well as to convert between circular polarization states.
• Smith, M. H., Denninghoff, K. R., Hillman, L. W., Hughes, C. E., Minnich, T. E., & Chipman, R. A. (1997). Technique for noninvasive monitoring of blood loss via oxygen saturation measurements in the eye. Proceedings of SPIE - The International Society for Optical Engineering, 2982, 46-52.
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  Abstract: We describe a noninvasive technique and instrumentation (the eye oximeter) for measuring the oxygen saturation of blood in retinal arteries and veins. A white-light image of a subject s retina is presented to an operator. The operator targets a particular retinal artery or vein and initiates the measurement procedure. The measurements are made by scanning low-power lasers into the eye and across the retinal vessel. The light reflected and scattered back out of the eye is collected and measured. The oxygen saturation of blood within the vessel is spectroscopically determined by analyzing the vessel absorption profiles at two or more wavelengths. A complete saturation measurement can be made in less than one second, allowing real-time measurement during physiologic changes. The sensitivity of this measurement technique to changes in retinal saturation has been demonstrated through a series of pilot studies in anesthetized swine. We present data indicating that retinal venous oxygen saturation decreases predicably during ongoing blood loss, indicating a potential application of an eye oximeter to noninvasively monitor blood loss. Current invasive techniques for monitoring bleeding, such as fiber optic pulmonary catheters, are not suited for use early in trauma situations. A portable eye oximeter may therefore provide a new technique for reducing mortality in the emergency department setting.
• Smith, M. H., Sornsin, E. A., Tayag, T. J., & Chipman, R. A. (1997). Mueller matrix imaging of GaAs/AlGaAs self-imaging beamsplitting waveguides. Proceedings of SPIE - The International Society for Optical Engineering, 3121, 47-54.
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  Abstract: Imaging polarimetry is a novel method of characterizing the polarization effects of optoelectronic devices. From the Mueller matrix image, any polarization property of a device can be determined. High resolution polarization images of the outcoupling faces of several self-imaging GaAs/AlGaAs waveguide beamsplitters were made in the Mueller Matrix Imaging Polarimeter at The University of Alabama in Huntsville. Interesting polarization effects were observed in these measurements. While the orientation of linear retardance was, uniformly aligned with the polarization states of the device modes (TE and TM), the magnitude of linear retardance varied significantly across a device. Polarization losses (diattenuation) were also observed to vary across the faces of the devices. These effects could not have been observed by simply measuring the crosstalk between the TE and TM modes. The results of this study could lead to the detection of defect mechanisms in optoelectronic devices through Mueller matrix measurements.
• Smith, M. H., Sornsin, E. A., Tayag, T. J., & Chipman, R. A. (1997). Polarization characterization of self-imaging GaAs/AlGaAs waveguide beamsplitters using Mueller matrix imaging polarimetry. Proceedings of SPIE - The International Society for Optical Engineering, 2994, 330-337.
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  Abstract: Mueller matrix imaging polarimetry represents a novel means of characterizing the polarization effects of optoelectronic devices. The Mueller matrix contains the complete polarization properties of a sample, and can therefore be used to calculate properties such as phase retardance, polarization dependant losses and polarization crosstalk. The complete polarization properties of a series of GaAs/AlGaAs self-imaging waveguide beamsplitters were measured with an imaging Mueller matrix polarimeter. Polarization properties were mapped across high resolution images of the devices' outcoupling faces, and the uniformity of the polarization properties was measured. Properties investigated include magnitude and orientation of linear retardance, polarization dependant losses, and crosstalk between TE and TM modes.
• Sornsin, E. A., & Chipman, R. A. (1997). Alignment and calibration of an infrared achromatic retarder using FTIR Mueller matrix spectropolarimetry. Proceedings of SPIE - The International Society for Optical Engineering, 3121, 28-34.
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  Abstract: An infrared achromatic retarder was aligned and characterized using the University of Alabama in Huntsville's Fourier Transform Infrared (FTIR) Spectropolarimeter. The FTIR Spectropolarimeter produces a full polarization description of a sample over wavelengths 3-14μm. Mueller matrices were measured for different relative alignments between the complementary plates of the achromat until the retardance orientation variation was reduced to within ±1° and the retardance magnitude varied smoothly with a peak-to-valley difference of 24° from 4-14μm. The results presented here include the progression of retardance magnitudes and retardance orientations as the plate alignment varied as well as the final Mueller matrix and retardance components of the achromat element.
• Sornsin, E. A., & Chipman, R. A. (1997). Electro-optic spatial light modulator characterization using Mueller matrix imaging. Proceedings of SPIE - The International Society for Optical Engineering, 3121, 161-166.
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  Abstract: A series of electro-optic spatial light modulators have been measured with the Mueller matrix imaging polarimeter (MMIP). The MMIP is a dual rotating-retarder polarimeter which illuminates a sample with calibrated polarized states and analyzes the exiting polarized state over a spatially-resolved image of the sample. Images of the retardance magnitude and retardance fast axis orientation reveal the relative electric field strengths in a device with lead-lanthanum-zirconate-titanate (PLZT 9/65/35) modulating material. By measuring Mueller matrix images of the device at several different applied voltages, a quadratic electro-optic coefficient of 2 × 10-16 (m/V)2 was determined in the modulator active regions.
• Sornsin, E. A., & Chipman, R. A. (1997). High-resolution Mueller matrix polarimetry of thin-film PLZT electro-optic modulators. Proceedings of SPIE - The International Society for Optical Engineering, 3008, 373-378.
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  Abstract: A thin-film lead-lanthanum-zirconate-titanate (PLZT) electro-optic spatial light modulator has been characterized with the Mueller matrix imaging polarimeter (MMIP). The MMIP is a dual rotating-retarder polarimeter which illuminates a sample with calibrated polarized states and analyzes the exiting polarized state over a spatially-resolved image of the sample. Images of the retardance magnitude and retardance fast axis orientation reveal the relative electric field strengths in the PLZT 9/65/35 material. By measuring Mueller matrix images of the device at several different applied voltages, a quadratic electro-optic coefficient of 2×10-16 (m/V)2 was determined in the modulator active regions.
• Sornsin, E. A., & Chipman, R. A. (1997). Visible Mueller matrix spectropolarimetry. Proceedings of SPIE - The International Society for Optical Engineering, 3121, 156-160.
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  Abstract: A Mueller matrix spectropolarimeter operating between 400-900nm has been developed for optical element characterization at The University of Alabama in Huntsville. Mueller matrices are measured as a function of wavelength and the spectral behavior of the polarization properties can be determined. Measurements of an achromatic retarder in transmission, a reflective beamsplitter, and the electro-optic dispersion of a spatial light modulator will be presented.
• Lu, S., & Chipman, R. A. (1996). Interpretation of Mueller matrices based on polar decomposition. Journal of the Optical Society of America A: Optics and Image Science, and Vision, 13(5), 1106-1113.
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  Abstract: We present an algorithm that decomposes a Mueller matrix into a sequence of three matrix factors: a diattenuator, followed by a retarder, then followed by a depolarizer. Those factors are unique except for singular Mueller matrices. Based on this decomposition, the diattenuation and the retardance of a Mueller matrix can be defined and computed. Thus this algorithm is useful for performing data reduction upon experimentally determined Mueller matrices. © 1996 Optical Society of America.
• Smith, M. H., Chipman, R. A., & Denninghoff, K. R. (1996). Oxygen saturation measurements of retinal arteries and veins during physiologic changes. Investigative Ophthalmology and Visual Science, 37(3), S840.
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  Abstract: Purpose. The development of an instrument to noninvasively measure the oxygen saturation of blood within retinal arteries and veins, and the characterization of retinal saturation variations during physiologic changes. Methods. A prototype Eye Oximeter (EOX) has been completed that shines low-power diode lasers into the eye and scans them across the large vessels of the retina. The reflected light intensities are digitized via 14-bit A/D, and transferred to a 486-based PC for analysis. Curve fitting techniques compensate for vessel specular reflections, and determine the percent absorption of the blood. Oxygen saturation is calculated from the measured absorptions at multiple wavelengths. A complete saturation measurement is made by averaging 8 scans occurring in less than one second. The EOX was used in a pilot study with anesthetized swine. Arterial measurements made during graded hypoxia provide in vivo calibration of the EOX. Retinal venous saturation (SrO2) was correlated with mixed venous saturation (Sv̄O2) as 20% of total blood volume was removed over 40 minutes. Results. We measured a strong correlation (r 2=0.96±0.03) between retinal arterial saturation and femoral artery blood gas measurements during graded hypoxia. During exsanguination, we measured a strong correlation (r2=0.86±0.09) between SrO2 and Sv̄O2. Conclusions. Due to the strong correlation between SrO2 and Sv̄O2 during blood loss, the EOX could provide a portable, noninvasive technique for early monitoring of occult bleeding.
• Takahashi, Y., Chipman, R. A., Dimmock, J. O., Hillmann, L. W., Lamb, D. J., Leslie, T. M., Weimer, J. J., Christl, M. J., Fishman, G. J., Parnell, T. A., Barbier, L. M., Boyce, K., Christian, E. R., Krizmanic, J. F., & Mitchell, J. W. (1996). Maximum-energy Auger (AIR)-shower satellite (MASS/AIRWATCH). Proceedings of SPIE - The International Society for Optical Engineering, 2806, 102-112.
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  Abstract: A concept for observation from space of the highest energy cosmic rays above 10 20 eV with a satellite-borne observatory has been considered. A maximum-energy auger (air)-shower satellite (MASS) would use segmented lenses (and/or mirrors) and an array of imaging devices (about 10 6 pixels) to detect and record fluorescent light profiles of cosmic ray cascades in the atmosphere. The field-of-view of MASS could be extended to about (1000 km) 2 so that more than 10 3 events per year could be observed above 10 20 eV. From far above the atmosphere, MASS would be capable of observing events at all angles including near horizontal tracks, and would have considerable aperture for high energy photon and neutrino observation. With a large aperture and the spatial and temporal resolution, MASS could determine the energy spectrum, the mass composition, and arrival anisotropy of cosmic rays from 10 20 eV to 10 22 eV, a region hitherto not explored by ground-based detectors such as the fly's eye and air-shower arrays. MASS's ability to identify comic neutrinos and gamma rays may help providing evidence for the theory which attributes the above cut-off cosmic ray flux to the decay of topological defects.
• Chipman, R. A. (1995). Mechanics of polarization ray tracing. Optical Engineering, 34(6), 1636-1645.
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  Abstract: Polarization ray tracing is a collection of methods that extends geometrical ray tracing allowing the calculation of the evolution of polarization states along ray paths and the determination of the intrinsic polarization properties, such as diattenuation and retardance, associated with ray paths. The suitability of the Jones, Mueller, and three-dimensional polarization ray tracing calculi are compared, examining the issues of local versus global coordinates, amplitude versus phase representations, inclusion of the wavefront aberration function, partially polarized light, measurements of images by polarimeters, and diffraction image formation by low- and high-numerical-aperture beams.
• Crandall, D. G., & Chipman, R. A. (1995). Polarization aberrations of crossed folding mirrors. Proceedings of SPIE - The International Society for Optical Engineering, 2537, 83-93.
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  Abstract: Polarization aberrations due to varying polarization state across the field of view (FOV) are investigated for crossed folding mirrors. We define crossed mirrors as oriented in space such that s-polarized light incident on the first mirror is p-polarized at the second mirror. This completely compensates for polarization state changes at one point in the field of view. The resulting polarization aberrations are explored across the FOV using the example of aluminum mirrors overcoated with a 12 layer, highly reflective, dielectric stack. The polarization aberration is very low along a band across the field of view. For arbitrary points in the FOV, the retardance and diattenuation are slightly elliptical.
• McClain, S. C., Bartlett, C. L., Pezzaniti, J., & Chipman, R. A. (1995). Depolarization measurements of an integrating sphere. Applied Optics, 34(1), 152-154.
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  Abstract: The depolarization measurements of a commercially available integrating sphere were performed using a Mueller-matrix polarimeter. These measurements determine the extent to which the light exiting an integrating sphere is unpolarized for all possible polarization states incident on the entrance port. The measurements were taken in the visible and near IR.
• Pezzaniti, J. L., & Chipman, R. A. (1995). Linear polarization uniformity measurements taken with an imaging polarimeter. Optical Engineering, 34(6), 1569-1573.
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  Abstract: Four types of polarizers are experimentally evaluated and compared for the uniformity of their transmission axis orientations and the contrast ratio and their spatial variation. Representative samples of calcite Glan-Thompson polarizers, polarizing beamsplitters, silver glass polarizers, and stretched polymer polarizers are characterized at 850 nm using a rotating polarizer imaging polarimeter. The sample Glan-Thompson polarizers show the highest contrast ratios and greatest uniformity of transmission axis. Silver glass polarizers and stretched polymer polarizers show intermediate contrast ratios, but all samples of both show a systematic variation of the transmission axis orientation with a magnitude of several tenths of a degree. The polarizing beamsplitter cube samples have very good uniformity of transmission axis but the smallest contrast ratios with noticeable spatial variations of contrast.
• Pezzaniti, J. L., & Chipman, R. A. (1995). Mueller matrix imaging polarimetry. Optical Engineering, 34(6), 1558-1568.
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  Abstract: The design and operation of a Mueller matrix imaging polarimeter is presented. The instrument is configurable to make a wide variety of polarimetric measurements of optical systems and samples. In one configuration, it measures the polarization properties of a set of ray paths through a sample. The sample may comprise a single element, such as a lens, polarizer, retarder, spatial light modulator, or beamsplitter, or an entire optical system containing many elements. In a second configuration, it measures an optical system's point spread matrix, a Mueller matrix relating the polarization state of a point object to the distribution of intensity and polarization across the image. The instrument is described and a number of example measurements are provided that demonstrate the Mueller matrix imaging polarimeter's unique measurement capability.
• Pezzaniti, J. L., & Chipman, R. A. (1995). Mueller matrix scatter polarimetry of a diamond-turned mirror. Optical Engineering, 34(6), 1593-1598.
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  Abstract: A novel technique for measuring the polarization light scattering function of surfaces using a Mueller matrix imaging scatter polarimeter is presented. This technique measures the near- specular scatter of reflective surfaces as Mueller matrix images, enabling the diattenuation, retardance, and depolarization of the scattered light to be determined. An example of measurements of a diamond-turned aluminum mirror with an rms roughness of 11.4 nm is presented and interpreted. The most surprising result in our data was that this scattering process created partially elliptical polarized light from unpolarized incident light, where we had expected essentially partially linearly polarized light.
• Chenault, D. B., & Chipman, R. A. (1994). Measurements of linear diattenuation and linear retardation spectra with a rotating sample spectropolarimeter: erratum. Applied Optics, 33(7), 1145-.
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  Abstract: This short note gives a correction for a typographical error in the equation for diattenuation published in an earlier paperin the journal `Applied Optics' 32, 3513-3519 (1993).
• Chenault, D. B., Chipman, R. A., & Shih-Yau, L. (1994). Electro-optic coefficient spectrum of cadmium telluride. Applied Optics, 33(31), 7382-7389.
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  Abstract: This paper presents a measurement of the electro-optic coefficient of CdTe. It is shown that electro-optic properties are constant in the range 8-14 μm, except for a small dip in the response near the absorption band around 6 μm. Measured Meuller matrix spectra are used for determination of retardance as a function of voltage and wavelength. The matrix spectra allows complete characterization of polarization properties including diattenuation, retardance and depolarization.
• Chipman, R. A. (1994). Progress in polarization ray tracing. Proceedings of SPIE - The International Society for Optical Engineering, 2265, 141-151.
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  Abstract: Polarization ray tracing is a collection of methods that extend geometrical ray tracing allowing the calculation of the evolution of polarization states along ray paths and the determination of the intrinsic polarization properties, such as diattenuation and retardance, associated with ray paths. This paper compares the suitability of the Jones, Mueller, and 3D polarization ray tracing calculi, examining the issues of local vs. global coordinates, amplitude vs. phase representations, inclusion of the wavefront aberration function, partially polarized light, measurements of images by polarimeters, and diffraction image formation by low and high numerical aperture beams.
• Chipman, R. A., & Pezzaniti, J. L. (1994). Imaging ellipsometry of optical coatings in situ. Proceedings of SPIE - The International Society for Optical Engineering, 2262, 124-134.
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  Abstract: A Mueller matrix imaging polarimeter has been developed and demonstrated for characterizing the polarization properties of optical coatings in place in optical systems. This Mueller matrix imaging polarimeter is a form of ellipsometer which measures the polarization characteristics of ray paths through systems in image form. It is a highly versatile instrument capable of making a variety of polarimetric measurements on optical samples or entire optical systems. Two data sets will be presented. The first shows the polarization behavior for example lenses which display the typical Maltese cross variation. The second shows images of polarizing beam splitter behavior as a function of angle of incidence, clearly showing how the plane of polarization as determined by the s- and p-planes rotates for light incident out of the normal plane.
• Lu, S., & Chipman, R. A. (1994). Homogeneous and inhomogeneous Jones matrices. Journal of the Optical Society of America A: Optics and Image Science, and Vision, 11(2), 766-773.
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  Abstract: The concepts of diattenuation and retardance are generalized on the basis of polar decomposition to include inhomogeneous polarization element. Explicit expressions of these concepts are derived in terms of Jones matrices elements. These expressions are used to perform data reduction in Jones matrices. Results of polarization elements classification by their unitary invariants, eigenvalues, and inhomogeneity are also discussed.
• McGuire Jr., J. P., & Chipman, R. A. (1994). Polarization aberrations. 1. Rotationally symmetric optical systems. Applied Optics, 33(22), 5080-5100.
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  Abstract: This paper presents the development of a formulation that takes into consideration phase-amplitude, linear diattenuation, and linear retardance effects of thin-film coatings on lenses and mirrors in aberration theory. Specifically, a discussion and calculation of an exponential expansion of the polarization aberrations for the case of strong polarization aberrations through fourth order, is described and applied to the understanding of polarization ray-tracing results. The theory is applicable to a variety of existing optical systems and for integration of thin-film design and optical design for optical systems that are polarization-sensitive.
• McGuire Jr., J. P., & Chipman, R. A. (1994). Polarization aberrations. 2. Tilted and decentered optical systems. Applied Optics, 33(22), 5101-5107.
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  Abstract: This paper presents the development of a polarization-aberration theory applicable to tilted and decentered systems. A polarization-aberration matrix is used for accurate calculations of the aberrations of systems with weakly polarizing coatings or small angles of incidence, where polarization is quadratic in the angle of incidence. Examples of such systems include: systems having elements whose center of curvature are collinear and pupils are decentered; and, systems having rotationally symmetric elements with arbitrary tilts and decenters. Analysis of a simple infrared scan-mirror is presented.
• Pezzaniti, J. L., Chipman, R. A., & McClain, S. C. (1994). Polarizer uniformity measurements taken with an imaging polarimeter. Proceedings of SPIE - The International Society for Optical Engineering, 2265, 113-118.
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  Abstract: The objective of this paper is to evaluate four types of polarizers in terms of three criteria: (1) their contrast ration, (2) the uniformity of their contrast ratios across 20 mm apertures, and (3) the uniformity of their transmission axis orientations across 20 mm apertures. The types of polarizers evaluated are calcite Glan-Thompson polarizers, polarizing beam splitters, silver glass polarizers, and stretched polymer polarizers. The measurements are performed with a rotating polarizer imaging polarimeter.
• Pezzaniti, J., & Chipman, R. A. (1994). Angular dependence of polarizing beam-splitter cubes. Applied Optics, 33(10), 1916-1929.
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  Abstract: Phenomenological data for three polarizing beam-splitter cubes is presented. The cube divides the incident beam on the basis of its polarization state. Description of the polarization aberration of such cubes is provided. Six figures of merit that provide the most useful polarization information about the cubes are measured with an imaging parameter over a ±10° field of view.
• Reiley, D. J., & Chipman, R. A. (1994). Coating induced wave-front aberrations: on-axis astigmatism and chromatic aberration in all-reflecting systems. Applied Optics, 33(10), 202-2012.
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  Abstract: Authors' earlier publication used commercial polarization ray tracing programs to demonstrate how coatings can degrade image quality in a Cassegrain telescope. This paper presents a theory of coating induced wavefront aberrations. Polarization aberration theory is used to show explicit relationship between the s- and p-phase change at optical interfaces and wavefront aberration expansion. Two results from polarization aberration theory are demonstrated: an all reflecting telescope can suffer from chromatic aberration; and coatings can induce on-axis astigmatism in a radially symmetric system.
• Cheault, D. B., & Chipman, R. A. (1993). Measurements of linear diattenuation and linear retardance spectra with a rotating sample spectropolarimeter. Applied Optics, 32(19), 3513-3519.
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  Abstract: The use of a rotating sample spectropolarimeter is described to measure linear diattenuation and linear retardance spectra. The technique is derived and demonstrated in the paper. A comparison is given of the rotating sample polarimeter to rotating retarder polarimeters. The configuration of the rotating sample polarimeter is shown. A schematic is presented showing the Fourier transform infrared spectropolarimeter.
• Chenault, D. B., & Chipman, R. A. (1993). Infrared birefringence spectra for cadmium sulfide and cadmium selenide. Applied Optics, 32(22), 4223-4227.
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  PMID: 20830073;Abstract: Measurements of the birefringence spectra for cadmium sulfide and cadmium selenide from 2.5 to 16.5 μm obtained with a rotating sample spectropolarimeter are presented. Because of the similarity in the birefringence spectra for cadmium sulfide and cadmium selenide, a highly achromatic IR retarder can be constructed from a combination of these materials. The ordinary and extraordinary refractive indices for cadmium sulfide are estimated in the region from 10.6 to 15 μm and for cadmium selenide from 10.6 to 16.5 μm by combining these birefringence data with an extrapolation of previous dispersion relations. © 1993 Optical Society of America.
• Chipman, R. A., Brown, D. M., & McGuire Jr., J. P. (1993). Polarization aberration analysis of the advanced x-ray astrophysics facility telescope assembly: Errata. Applied Optics, 32(22), 4236-4237.
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  PMID: 20830076;
• Hilman, L. W., & Chipman, R. A. (1993). Polarization ray tracing in anisotropic optically active media. II. Theory and physics. Journal of the Optical Society of America A: Optics and Image Science, and Vision, 10(11), 2383-2393.
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  Abstract: Refraction, reflection, and amplitude relations are derived for polarization ray tracing in quartz. Maxwell's equations are discussed together with an eigenvalue equation, and Fresnel equations for transmission and reflection.
• McClain, S. C., Hillman, L. W., & CHipman, R. A. (1993). Polarization ray tracing in anisotropic optically active media. I. Algorithms. Journal of the Optical Society of America A: Optics and Image Science, and Vision, 10(11), 2371-2382.
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  Abstract: This paper presents a polarization ray-tracing procedure incorporating crystalline quartz. Algorithms for refraction and reflection are described like polarization ray tracing in optically active uniaxial media. A description is given of birefringent media, and quartz parameters. Fresnel coefficients, and ray transfer and optical path lengths are described.
• Pezzanaiti, J. L., & Chipman, R. A. (1993). Phase-only modulation of a twisted nematic liquid crystal TV by use of the eigenpolarization states. Optics Letters, 18(18), 1567-1569.
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  Abstract: Measured eigenpolarization states of an InFocus TVT-6000 liquid crystal television (LCTV) for 0-255 range gray levels are reported. It is shown that the eigenpolarization states remain nearly constant with dependence on gray level for several bias voltage settings. The LCTV eigenpolarization states were computed from Mueller matrix.
• Pezzaniti, J. L., Chipman, R. A., & Gregory, D. A. (1993). Polarization characterization of an LCTV with a Mueller matrix imaging polarimeter. Proceedings of SPIE - The International Society for Optical Engineering, 1959, 235-247.
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  Abstract: The polarization properties of a TVT-6000 LCTV have been investigated. Mueller matrices of multiple ray paths through the TVT-6000 were measured for a single (typical) pixel, and through several pixels, using an imaging polarimeter. The TVT-6000 was characterized as a function of applied voltage and angle of incidence. From the Mueller matrices, the spatially dependent retardance, diattenuation, and depolarization are calculated and displayed as topographic maps. In another set of measurements, the LCTV is illuminated with a plane wave, and the spatial distribution of polarization in the Far Field Diffraction Pattern is measured in Mueller matrix form.
• Pezzaniti, L. J., McClain, S. C., Chipman, R. A., & Lu, S. (1993). Depolarization in liquid-crystal televisions. Optics Letters, 18(23), 2071-2073.
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  Abstract: TVT-6000 liquid crystal television (LCTV) polarization properties have been mapped as a function of biased voltage to the pixel and angle of incidence by a Mueller-matrix imaging polarimeter at 632.8 nm. Operating without polarizers the LCTV shows between 2% to 9% depolarization depending on angle of incidence, the incident polarization state, and the pixel bias voltage.
• Chenault, D. B., Pezzaniti, J. L., & Chipman, R. A. (1992). Mueller matrix algorithms. Proceedings of SPIE - The International Society for Optical Engineering, 1746, 231-246.
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  Abstract: A method for the correction of systematic errors generated by large orientational and retardance errors in the polarization optics in the dual rotating retarder polarimeter is presented. Small orientational and retardance errors ( 10% in some matrix elements). We incorporate correction terms for large orientation and retardance errors into the dual rotating retarder data reduction algorithm. Using these data reduction algorithms and a calibration step, the associated systematic errors are calculated and removed from the measured Mueller matrix. This procedure is especially useful for spectral and multi-wavelength systems in which the retardance and often the orientation of the retarders are wavelength dependent. The equations, the procedure to calculate the orientations of the polarization elements and the retardances of the retardation elements, and the method to correct for any errors are presented here. The effect of these errors on the calculated Mueller matrix elements and their correction is shown analytically and through experimental data taken on an infrared spectropolarimeter.
• Chipman, R. A. (1992). Mechanics of polarization ray tracing. Proceedings of SPIE - The International Society for Optical Engineering, 1746, 62-75.
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  Abstract: Polarization ray tracing, which consist of several extensions to geometrical ray tracing, calculates the evolution of polarization states along ray paths and determines the intrinsic polarization properties, such as diattenuation and retardance, associated with ray paths. This paper compares the suitability of the Jones, Mueller, and a three-dimensional polarization ray tracing calculi, examining the issues of local versus global coordinates, amplitude versus phase representations, inclusion of the wavefront aberration function, partially polarized light, measurements of images by polarimeters, and diffraction image formation by low and high numerical aperture beams.
• Chipman, R. A. (1992). Precision polarimetry of polarization components. Proceedings of SPIE - The International Society for Optical Engineering, 1746, 49-60.
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  Abstract: Polarization elements are inadequately characterized for many applications. For retarders, usually only the retardance is specified. For polarizers, usually only the two principal transmittances or the extinction ratio are given. For polarization elements used in critical applications, this level of characterization is woefully inadequate. Defects of polarization elements are described, and the Mueller calculus suggested as the most appropriate measure of performance. Examples of the characterization of polarization elements as a function of angle of incidence, and as a function of wavelength are provided.
• Lu, S., & Chipman, R. A. (1992). Generalized diattenuation and retardance for inhomogeneous polarization elements. Proceedings of SPIE - The International Society for Optical Engineering, 1746, 197-200.
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  Abstract: Two useful quantities, diattenuation and retardance, that characterize the polarization properties of a polarization element, are generalized for inhomogeneous polarization elements, i.e., the polarization elements with nonorthogonal eigenpolarizations. Moreover, an inhomogeneity parameter is introduced to characterize the inhomogeneity of a polarization element. The equations for calculating inhomogeneity, diattenuation, and retardance from the Jones matrix are presented. These equations are suitable for performing data reduction on Jones matrices or nondepolarizing Mueller matrices.
• Maymon, P. W., & Chipman, R. A. (1992). Linear polarization sensitivity specifications for spaceborne instruments. Proceedings of SPIE - The International Society for Optical Engineering, 1746, 148-156.
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  Abstract: The radiometric accuracy of space-borne instruments such as radiometers and spectroradiometers which make measurements of the earth and other celestial objects can be compromised by the linear polarization sensitivity (LPS) induced by the optical system. Most of these optical systems contain optical elements whose reflectance or transmission is polarization dependent, such as diffraction gratings, folding and scanning mirrors, dichroic filters, and optical fibers. Optical systems incorporating such elements generally display linear polarization sensitivity; different linear polarization states incident with equal radiometric power are measured as different power levels. If the incident polarization state is unknown, the linear polarization sensitivity cannot be compensated during the data reduction. The light reflected from the earth and other planets and moons is usually partially linearly polarized, but in a random distribution. Thus, to make accurate radiometric measurements of these bodies, a radiometer or spectrometer should have a low level of linear polarization sensitivity. This paper contains a mathematical description of LPS, contains references to systems which have imposed an LPS specification, describes some of the sources of LPS, describes how to model LPS by polarization ray tracing, and discusses methods to reduce the LPS of an optical system.
• McClain, S. C., & Chipman, R. A. (1992). Polarization ray tracing in anisotropic optically active media. Proceedings of SPIE - The International Society for Optical Engineering, 1746, 107-118.
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  Abstract: Procedures for performing polarization ray tracing through birefringent media are presented in a form compatible with the standard methods of geometric ray tracing. The birefringent materials treated include the following: anisotropic optically active materials such as quartz, non-optically active uniaxial materials such as calcite, and isotropic optically active materials such as mercury sulfide or organic liquids. Refraction and reflection algorithms are presented which compute both ray directions and wave directions. Methods for computing polarization modes, refractive indices, optical path lengths, and Fresnel transmission and reflection coefficients are also specified.
• McClain, S. C., Maymon, P. W., & Chipman, R. A. (1992). Design and analysis of a depolarizer for the NASA MODerate-resolution Imaging Spectrometer-Tilt (MODIS-T). Proceedings of SPIE - The International Society for Optical Engineering, 1746, 375-385.
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  Abstract: The design and analysis of a depolarizer for the NASA MODIS-T spectrometer is presented. The theory of spatial pseudodepolarizer operation and its effect on linear polarization sensitivity is described. Details of the HV depolarizer design and issues of depolarizer location and material are discussed. The image doubling and aberrations induced by the depolarizer and the trade-offs between increased polarization performance and decreased image quality are also addressed. The issues considered apply directly to depolarizer design for other remote sensing instruments.
• Pezzaniti, J. L., & Chipman, R. A. (1992). Off-axis polarizing properties of polarizing beamsplitter cubes. Proceedings of SPIE - The International Society for Optical Engineering, 1746, 343-357.
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  Abstract: The field of view dependence of polarizing beam splitter cubes has been studied to characterize their behavior in imaging systems, such as optical computers, optical correlators, and other applications which involve non-collimated light. Significant polarization aberration is present in polarizing beam splitter cubes for two reasons, (1) the s and p orientations at the beamsplitting interface, which define the polarizing axes, vary with direction of propagation; and (2) the coating performance is a function of angle of incidence. Here we present measurements made on several polarizing beam splitter cubes from various vendors. The measurements show typical polarization behavior which is of concern when the cubes are used in imaging systems. A near infra-red imaging polarimeter is used to measure the cubes.
• Reardon, P. J., & Chipman, R. A. (1992). Lens measurement in fundamental units of length and power. Proceedings of SPIE - The International Society for Optical Engineering, 1690, 4-10.
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  Abstract: A lens configuration called the limiting lens has been studied which describes the highest power, shortest focal length system for a given cylindrical volume. We consider here the classification and study of lenses which are constrained to fit into small packages in terms of how close the configurations come to the limiting lens.
• Reardon, P. J., Chipman, R. A., & Pietrzak Jr., S. F. (1992). Calculation of rotationally symmetric multi-focal lens surface.. Journal of the American Optometric Association, 63(2), 140-144.
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  PMID: 1583268;Abstract: A numerical method to calculate surfaces for refractive multi-focal intraocular lenses is presented. The computations, performed in a plane containing the axis of rotation of the surface, provide sag values as well as the curvature of the surface between values. Standard ray tracing techniques may then be applied to the calculated surface to verify the optical performance.
• Reiley, D. J., & Chipman, R. A. (1992). Adjustable distortion correctors. Proceedings of SPIE - The International Society for Optical Engineering, 1690, 11-19.
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  Abstract: Distortion can be corrected in an image by placing a fourth-order aspheric optical element near the image plane. Moving the aspheric surface longitudinally changes the amount of distortion added by the aspheric surface without changing the paraxial image. This ability to readily adjust the amount of image correction can be a powerful design tool for distortion-critical optical systems, such as digital optical computers. Third order astigmatism limits the performance of distortion correctors and may be eliminated by adding another fourth-order aspheric surface. Example elements were fabricated using diamond turning and were shown to introduce distortion without significantly degrading image quality. Three arrangements of distortion correctors are discussed: a single-element plano-aspheric arrangement, an anti- symmetric two-element arrangement, and a biaspheric arrangement in which distortion is not adjustable.
• Reiley, D. J., & Chipman, R. A. (1992). Coating-induced wavefront aberrations. Proceedings of SPIE - The International Society for Optical Engineering, 1746, 139-146.
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  Abstract: Distortion can be corrected in an image by placing a fourth-order aspheric optical element near the image plane. Moving the aspheric surface longitudinally changes the amount of distortion added by the aspheric surface without changing the paraxial image. This ability to readily adjust the amount of image correction can be a powerful design tool for distortion-critical optical systems, such as digital optical computers. Third order astigmatism limits the performance of distortion correctors and may be eliminated by adding another fourth-order aspheric surface. Example elements were fabricated using diamond turning and were shown to introduce distortion without significantly degrading image quality. Three arrangements of distortion correctors are discussed: a single-element plano-aspheric arrangement, and anti-symmetric two-element arrangement, and a biaspheric arrangement in which distortion is not adjustable.
• Chenault, D. B., & Chipman, R. A. (1990). Linear diattenuation and retardance measurements in an IR spectropolarimeter. Proceedings of SPIE - The International Society for Optical Engineering, 1317, 263-278.
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  Abstract: A technique to measure linear diattenuation and retardance spectra of infrared samples in transmission has been developed. A sample is rotated between two fixed linear polarizers in the sample compartment of an infrared spectrometer. The intensity modulation resulting from the rotation of the sample is Fourier analyzed and the diattenuation and retardation of the sample are calculated from these Fourier series coefficients. For single plate devices, such as waveplates, sheet polarizers, or liquid crystals, whose thickness is known, the birefringence spectrum can also be determined. This technique has been utilized in the sample compartment of a Fourier transform infrared spectropolarimeter to determine the linear diattenuation and retardance spectra from 2.5 to 16.5 microns of an infrared multiple order retarder, two achromatic retarders, and a liquid crystal sample.
• Chipman, R. A. (1990). Polarimetric impulse response and polarimetric transfer function for time sequential polarimeters. Proceedings of SPIE - The International Society for Optical Engineering, 1317, 223-241.
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  Abstract: An analysis of polarimetric measurements in the presence of noise is presented with emphasis on rotating polarizer polarimeters. A method is presented for estimating the error bars associated with a polarization measurement of an object whose intensity is rapidily fluctuating in a noisy manner. The method requires knowledge of the power spectral density of the intensity fluctuation, and uses this information combined with the sequence of polarizing element settings and measurement times to determine the error bar estimate. The rotating polarizer polarimeter is used as an example of this technique. A relationship is established between the power spectrum of the source intensity fluctuations and the error bars associated with measurements of the stokes vector elements. The impulse response and transfer function of a polarimetric measurement and data reduction sequence are introduced.
• Hodgson, R. R., & Chipman, R. A. (1990). Measurement of corner cube polarization. Proceedings of SPIE - The International Society for Optical Engineering, 1317, 436-447.
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  Abstract: Corner cube retroreflectors are geometrically simple devices which have fascinating optical properties. Photographs of corner cube retroreflectors using a polarimeter and collimated laser illumination have verified their polarization properties. The Jones calculus and Pauli spin matrix coefficients have been utilized to classify the observed results.
• Pezzaniti, J. L., & Chipman, R. A. (1990). Imaging polarimeters for optical metrology. Proceedings of SPIE - The International Society for Optical Engineering, 1317, 280-294.
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  Abstract: In this paper we describe two configurations of imaging polarimeters designed for polarimetric optical metrology. The first is a Stokes imaging polarimeter which measures the polarization response of optical systems to spherical or planar waves of known polarization. The output is images of the degree of polarization, orientation and eccentricity of polarization ellipses, or Stokes parameters displayed as a function of either the exit pupil or image coordinate of the optical system. The second configuration is a Mueller imaging polarimeter which measures the Mueller matrix of an optical system on a ray by ray basis. Calibration issues involved in building these instruments are addressed along with a brief discussion on polarization aberration mechanisms.
• Pezzaniti, J. L., Hadaway, J. B., Chipman, R. A., Wilkes, D., Hummer, L., & Bennett, J. (1990). Total Integrated Scatter instrument for in-space monitoring of surface degradation. Proceedings of SPIE - The International Society for Optical Engineering, 1329, 200-210.
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  Abstract: A Total Integrated Scatter (TIS) system was built to test the viability of a TIS instrument to be used in space to monitor damage to optical and thermal control surfaces due to the low earth orbit environment. The systems accuracy and repeatability in detecting changes in the surface quality of various space materials after exposure to atomic oxygen was tested. A method for distinguishing roughening of a surface from dust contamination is described.
• Reardon, P. J., & Chipman, R. A. (1990). Lens with maximum power occupying a given cylindrical volume. Proceedings of SPIE - The International Society for Optical Engineering, 1354, 234-239.
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  Abstract: This paper describes a method by which designs for high power lenses, and lenses constrained to very short spaces can be evaluated or started. First, the fundamentally highest power refractive lens is presented. Then, the paraxial properties of this lens are fully described, followed by a brief third order analysis.
• Chipman, R. A. (1989). Polarization analysis of optical systems. Optical Engineering, 28(2), 090-099.
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  Abstract: For most optical systems it is assumed that the transmitted wavefront has uniform (or Gaussian) amplitude and constant polarization state. This is the default assumption of geometrical optics. This paper considers methods suitable for analyzing systems for which this assumption is not valid. Such methods of polarization analysis include polarization ray tracing and polarization aberration theory. Definitions of the basic classes of polarization phenomena and a review of the Jones calculus are included to form a basis for the discussion.
• Chipman, R. A., & Chipman, L. J. (1989). Polarization aberration diagrams. Optical Engineering, 28(2), 100-106.
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  Abstract: Polarization aberrations are variations of the polarization associated with different ray paths through an optical system. This paper presents a polarization aberration expansion that is second order in the object and pupil coordinates and describes polarization effects that are functionally equivalent to the wavefront aberration terms: piston, tilt, and defocus. This polarization aberration expansion is applicable to weakly polarizing systems, such as radially symmetric systems of lenses and coatings, as well as to strongly, polarizing systems incorporating polarizers and retarders. A computer simulation of this expansion has been performed, and graphical results are presented displaying the effect of 24 of these polarization aberrations acting on linearly and circularly polarized light.
• Goldstein, D. H., Chipman, R. A., & Chenault, D. B. (1989). Infrared spectropolarimetry. Optical Engineering, 28(2), 120-125.
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  Abstract: This paper treats the fundamentals of infrared spectropolarimetry as a step in understanding electro-optical materials and designing better spatial light modulators. It describes the issues in converting a Fourier transform spectrometer to perform spectropolarimetric measurements and includes mathematics to interpret the resulting spectropolarimetric data. Two differences exist between this proposed instrumentation and previous infrared crystal optics studies: (1) this instrument acquires data simultaneously at all wavelengths within its spectral range and (2) it measures Mueller polarization matrices. Conventional measurements with laser polarimeters take birefringence data with applied fields at a few laser wavelengths. With the spectropolarimeter, data are obtained over the entire spectrum, including on and near absorption bands where the most interesting phenomena occur. Measuring Mueller matrices as a function of wavelength provides data on polarization and scattering, effects that will ultimately limit the performance of a modulating crystal.
• McGuire Jr., J. P., & Chipman, R. A. (1989). Polarization aberrations in the solar activity measurements experiments (SAMEX) solar vector magnetograph. Optical Engineering, 28(2), 141-147.
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  Abstract: An optical design and polarization analysis of the Air Force/NASA Solar Activity Measurements Experiments solar vector magnetograph optical system is performed. Polarization aberration theory demonstrates that conventional telescope coating designs introduce high levels of polarization aberrations into the optical system. Several ultralow polarization mirror and lens coatings designs for this instrument are discussed. Balancing of polarization aberrations at different surfaces is demonstrated.
• Chipman, R. A. (1987). POLARIZATION RAY TRACING.. Proceedings of SPIE - The International Society for Optical Engineering, 766, 61-68.
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  Abstract: A method of polarization ray tracing for calculating the instrumental polarization function of an optical system using the Jones calculus is presented. Polarization ray tracing supplements the equations of ray tracing to include amplitude, phase, polarization and retardance effects of thin films, polarization elements and polarizing materials. Results of a polarization ray trace analysis of a Cassegrain telescope are presented.
• Chipman, R. (1986). POLARIZATION ABERRATIONS OF LENSES.. Proceedings of SPIE - The International Society for Optical Engineering, 554, 82-87.
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  Abstract: Polarization aberrations are variations of intensity and polarization of an optical beam in the exit pupil of an optical system, and the dependence of these variations on the position of the object in the field. A set of functions has been derived to describe the low-order polarization aberrations of a symmetric optical system. A method is given for calculating polarization aberration coefficients for a refracting system from a paraxial raytrace. A model of these aberrations as weak polarizers that vary across the pupil will be discussed.
• Chipman, R. A. (1983). HIGH PRECISION ANGLE MEASUREMENTS OFF SMALL SURFACES.. Proceedings of SPIE - The International Society for Optical Engineering, 429, 148-152.
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  Abstract: A method is described for measuring the orientation of small plane surfaces several tens of micrometers on a side with a resolution of several seconds of arc. A laser beam waist is located on the test surface which underfills the surface. The reflected beam is detected by a quadrant detector to determine the offset of the beam from its nominal position. This displacement determines the relative angular difference from a predetermined angular standard. Advantages of this method for precise angle determination are the ability to measure small surfaces, insensitivity to translations of the test piece, large test piece clearance for inaccessible surfaces, and compensation for laser drift.
• Chipman, R. A. (1980). MONOCHROMATOR DESIGNS WITH ABERRATION CORRECTED GRATINGS.. Proceedings of the Society of Photo-Optical Instrumentation Engineers, 237, 439-445.
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  Abstract: Seya-Namioka monochromators using concave aberration corrected holographic gratings have been designed to cover the spectrum from 180-900 nm. This broad wavelength range (4. 5 octaves) severely tests the aberration correction ability of this monochromator. All holographic Seya-Namioka monochromators displayed severe loss of resolution at one or both ends of the spectrum.

Proceedings Publications

• Li, L. W., Chipman, R. A., & Kupinski, M. K. (2020). Effects of surface roughness and albedo on depolarization in Mueller matrices. In Polarization: Measurement, Analysis, and Remote Sensing XIV, 11412.
• Omer, K., Chipman, R., & Kupinski, M. (2020). Road scene object detection using pre-trained RGB neural networks on linear Stokes images. In Polarization: Measurement, Analysis, and Remote Sensing XIV, 11412.
• Breckinridge, J. B., Harvey, J. E., Irvin, R., Chipman, R., Kupinski, M., Davis, J., Kim, D. W., Douglas, E., Lillie, C. F., & Hull, T. (2019, 2019/9/9 DOI - 10.1117/12.2528825). ExoPlanet Optics: conceptual design processes for stealth telescopes. In ExoPlanet Optics: conceptual design processes for stealth telescopes, 11115.
• Hart, K. A., Amici, G. D., Horne, T., Kupinski, M., Langworthy, K., Stohn, A., Wu, D. L., & Chipman, R. (2019, 2019/9/10 DOI - 10.1117/12.2532075). Demonstration of LWIR channeled spectro-polarimeter (Conference Presentation). In Demonstration of LWIR channeled spectro-polarimeter (Conference Presentation), 11132.
• Kimura, R., Seigo, M., Chipman, R. A., & Kitagawa, S. (2019, 2019/2/26 DOI - 10.1117/12.2506129). Optical simulation for illumination using GPGPU ray tracing. In Optical simulation for illumination using GPGPU ray tracing, 10912.
• Richter, J. M., Chipman, R., Daugherty, B., Diner, D. J., Eldering, A., Hyon, J. J., Kupinski, M., Neu, J. L., & Fu, D. (2019, 2019/5/22 DOI - 10.1117/12.2510750). Specifying polarimetric tolerances of a high-resolution imaging multiple-species atmospheric profiler (HiMAP). In Specifying polarimetric tolerances of a high-resolution imaging multiple-species atmospheric profiler (HiMAP), 10925.
• , J., Kupinski, M. K., Chipman, R. A., & Breckinridge, J. B. (2018, 2018/7/16). HabEx polarization ray trace and aberration analysis. In HabEx polarization ray trace and aberration analysis, 10698.
• Banerjee, S., Chipman, R., Hagen, N., & Otani, Y. (2018, 2018). Experimental determination of Berry phase introduced by three mirrors using spectroscopic Mueller matrix polarimeter. In Experimental determination of Berry phase introduced by three mirrors using spectroscopic Mueller matrix polarimeter, 30aBJ5.
• Gillis, J. M., Chipman, R. A., Diner, D. J., & Dubin, M. B. (2018, 2018/5/14). Polarization considerations in the multi-angle imager for aerosols (MAIA). In Polarization considerations in the multi-angle imager for aerosols (MAIA), 10655.
• Hart, K. A., Chipman, R. A., & Wu, D. L. (2018, 2018/5/14). Compact LWIR polarimeter for cirrus ice properties. In Compact LWIR polarimeter for cirrus ice properties, 10655.
• Li, L. W., & Chipman, R. A. (2018, 2018/5/14). Short-wave infrared Mueller matrices and polarization parameters for in vivo skin surface reflectance. In Short-wave infrared Mueller matrices and polarization parameters for in vivo skin surface reflectance, 10655.
• , K., & , R. (2017, 2017). Modeling the polarization aberrations of optical elements (Conference Presentation). In Modeling the polarization aberrations of optical elements (Conference Presentation), 10407, 1040708.
• Chipman, R. A. (2017, 2017). Challenges in coronagraph optical design. In Challenges in coronagraph optical design, 10374, 1037403-10374-12.
• Chipman, R. A. (2017, 2017). Image formation in coronagraphs due to mirror polarization aberrations. In Image formation in coronagraphs due to mirror polarization aberrations, 10590, 105901V-10590-7.
• Chipman, R. A. (2016). Aberration Functions Due To Coatings. In Optical Interference Coatings 2016.
• Chipman, R. A. (2015). Berry Phase and Polarization Aberration. In Frontiers in Optics 2015.
• Chipman, R. A. (2014, June). Characterization of DKIST retarder components with polarization ray tracing. In International Optical Design Conference, 929308-929308-5.
• Chipman, R. A. (2014, October). The Polarization Ray Tracing Calculus. In Frontiers in Optics, FM4D--1.
• Chipman, R. A., & Young, G. (2014, June). Multi-order Retarders and the Mystery of Retardance Discontinuities. In Computational Optical Sensing and Imaging, JTu5A--25.
• Young, G., & Chipman, R. A. (2014). Multi-order Retarders and the Mystery of Retardance Discontinuities. In Classical Optics 2014.
• Young, G., Chipman, R. A., & Lam, W. T. (2014, June). A review of skew aberration, the intrinsic polarization aberration in high NA optical systems. In International Optical Design Conference, 92931X--92931X.

Poster Presentations

• Chipman, R. A., Seidel, F. C., Diner, D. J., Kalashnikova, O. V., Xu, F., Rheingans, B. E., Garay, M. J., Daugherty, B. J., & Davis, A. (2015, April). Airborne Multi-angle SpectroPolarimeter Imager (AirMSPI): Polarimetric Calibration, Validation and Aerosol Retrieval Example from the SEAC4RS campaign. SEAC4RS Sci team meeting. Pasadena, CA: NASA.
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  The Airborne Multi-angle SpectroPolarimetric Imager(AirMSPI)[1] is a pushbroom multi-angle spectropolarimetriccamera with spectral bands near 355, 380,445, 470, 555, 660, 865, and 935 nm. Flying on NASAs'shigh-altitude ER-2 aircraft since 2010, AirMSPI uses dualphotoelastic modulator (PEM)-based technology [2] toachieve accurate measurements of the Stokes linearpolarization parameters Q and U in the 470, 660, and 865nm bands. This provides unique observing capabilities foraerosol, cloud, and surface studies.We describe the polarimetric measurement, calibration, andaccuracy of the AirMSPI instrument. A well-calibratedPolarization State Generator is used to provide knownpolarimetric inputs. A high-extinction rotating wiregridpolarizer is used to derive polarimetric calibrationcoefficients for each pixel, and the results are thenvalidated using partially polarized light generated usingtilted glass plates.We also provide an overview of the AirMSPI data collectedduring the SEAC4RS campaign in collocation with otherremote sensing and in-situ data. And in addition,preliminary retrieval example of spatially resolved aerosoloptical depth (AOD) and single scattering albedo (SSA) areshown in good agreement with reference data from theAerosol Robotic Network (AERONET).