John Koshel

Interests

Teaching

Illumination optics, nonimaging optics, optical design, radiometry

Research

Illumination optics, nonimaging optics, optical design, radiometry, solid-state lighting, solar energy, computer graphics and rendering

Courses

Scholarly Contributions

Journals/Publications

• Fang, Y. C., Liang, C., Koshel, J., Sasian, J., Yatagai, T., Wang, Y., & Zavisian, J. M. (2015). Optical design and testing: introduction. Applied optics, 54(28), ODT1-2.
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  Optical design and testing have numerous applications in industrial, military, consumer, and bio-medical settings. This issue features original research ranging from the optical design of image and nonimage optical stimuli for human perception, optics applications, bio-optics applications, displays, and solar energy systems to novel imaging modalities from deep UV to infrared spectral imaging, a systems perspective to imaging, as well as optical measurement. In addition, new concepts and trends for optics and further optical systems will be especially highlighted in this special issue.
• Keresztes, J. C., De, K. B., Audenaert, J., Koshel, R. J., & Saeys, W. (2015). Illumination system development using design and analysis of computer experiments. NOVEL OPTICAL SYSTEMS DESIGN AND OPTIMIZATION XVIII, 9579.
• Koshel, R. J. (2015). Illumination system tolerancing. OPTICAL SYSTEM ALIGNMENT AND TOLERANCING, 6676.
• Koshel, R. J., & Mulder, S. (2015). Toleranced freeform optical design with extended sources using ray targeting. NOVEL OPTICAL SYSTEMS DESIGN AND OPTIMIZATION XVI, 8842.
• Keresztes, J. C., Koshel, R. J., Chipman, R., Stover, J. C., & Saeys, W. (2014). A cross-polarized freeform illumination design for glare reduction in fruit quality inspection.. OPTICAL SYSTEMS DESIGN 2015: ILLUMINATION OPTICS IV, 9629.
• Liang, C., Koshel, J., Sasian, J., Breault, R., Wang, Y., & Fang, Y. C. (2014). Optical design and testing: introduction. Applied optics, 53(29), ODT1-4.
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  Optical design and testing has numerous applications in industrial, military, consumer, and medical settings. Assembling a complete imaging or nonimage optical system may require the integration of optics, mechatronics, lighting technology, optimization, ray tracing, aberration analysis, image processing, tolerance compensation, and display rendering. This issue features original research ranging from the optical design of image and nonimage optical stimuli for human perception, optics applications, bio-optics applications, 3D display, solar energy system, opto-mechatronics to novel imaging or nonimage modalities in visible and infrared spectral imaging, modulation transfer function measurement, and innovative interferometry.
• Keresztes, J. C., Aernouts, B., Koshel, R. J., & Saeys, W. (2013). Dynamic noise corrected hyperspectral radiometric calibration in the SWIR range using a Supercontinuum laser. NOVEL OPTICAL SYSTEMS DESIGN AND OPTIMIZATION XVIII, 9579.
• Seassal, C., & Koshel, J. (2013). Focus issue introduction: renewable energy and the environment. Optics express, 21 Suppl 3, A430-2.
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  This focus issue highlights selected contributions from authors who presented promising concepts at OSA's Renewable Energy and the Environment Optics and Photonics Congress held 11-15 November 2012 in Eindhoven, The Netherlands.
• Kim, J. J., & Koshel, R. J. (2010). Modeling Transflective LCD Illumination Systems. INTERNATIONAL OPTICAL DESIGN CONFERENCE 2010, 7652.
• Koshel, R. J., Seassal, C., Deparis, O., & Kumar, R. (2010). Focus issue introduction: Renewable energy and the environment 2013. OPTICS EXPRESS, 22(5), A561-A563.
• Koshel, R. J. (2008). Software conquers design and analysis of backlit LCDs. LASER FOCUS WORLD, 43(10), 62-+.
• Gregory, G. G., & Koshel, R. J. (2007). Introduction. NOVEL OPTICAL SYSTEMS DESIGN AND OPTIMIZATION XIII, 7787, IX-X.
• Koshel, R. J. (2007). A course in illumination engineering - art. no. 66680F. NOVEL OPTICAL SYSTEMS DESIGN AND OPTIMIZATION X, 6668, F6680-F6680.
• Koshel, R. J. (2007). Fractional Optimization of Illumination Optics. NOVEL OPTICAL SYSTEMS DESIGN AND OPTIMIZATION XI, 7061.
• Koshel, R. J. (2007). Why illumination engineering? - art. no. 667002. NONIMAGING OPTICS AND EFFICIENT ILLUMINATION SYSTEMS IV, 6670, 67002-67002.
• Gregory, G. G., & Koshel, R. J. (2006). Modeling the operating conditions of solar concentrator systems - art. no. 61970J. Photonics for Solar Energy Systems, 6197, J1970-J1970.
• Kintner, E. C., Wong, W. K., Jacobs, E. S., Cucchiaro, P. J., & Koshel, R. J. (2006). Efficient and versatile internal reference sources for remote sensing space telescopes - art. no. 62970F. Infrared Spaceborne Remote Sensing XIV, 6297, F2970-F2970.
• Koshel, R. J. (2006). Optimization of parameterized lightpipes - art. no. 63420P. International Optical Design Conference 2006, Pts 1 and 2, 6342, P3420-P3420.
• Koshel, R. J. (2005). Simplex optimization method for illumination design. Optics letters, 30(6), 649-51.
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  A modified simplex optimization method is developed for the design of illumination systems. The simplex method is a judicious choice for illumination optimization because of its robustness and convergence properties. To optimize the simplex method, its four parameters are adjusted dependent on the dimensionality of the space to converge with fewer iterations. This work is presented for the end game, when the optimizer is converging on a local optimum rather than searching for it. Up to a 37% reduction in the number of computations is realized. An example using a compound parabolic concentrator is compared between the standard and the modified simplex methods, providing over 22% improvement in the end game.
• Koshel, R. J., & Walmsley, I. A. (2004). Non-edge-ray design: improved optical pumping of lasers. OPTICAL ENGINEERING, 43(7), 1511-1521.
• Gupta, A., Lee, J., & Koshel, R. J. (2001). Design of Efficient LightPipes for Illumination by an Analytical Approach. Applied optics, 40(22), 3640-8.
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  We present the concept of principal sections of a lightpipe to analyze the propagation of light through the lightpipe by total internal reflection. Only the principal sections determine the acceptance angle and thus help in the identification of regions where the leakage occurs first. Use of principal sections for analysis leads to a significant reduction in the design effort. We present an analysis of several commonly used lightpipe configurations, e.g., straight and single circular bend, and different cross sections, e.g., elliptical and rectangular. This analysis leads to the maximization of throughput and transfer efficiency. The uniformity characteristics of elementary configurations and scaling factors for a lightpipe with a single circular bend are also discussed.
• Koshel, R. J., & Walmsley, I. A. (1993). Modeling of the gain distribution for diode pumping of a solid-state laser rod with nonimaging optics. Applied optics, 32(9), 1517-27.
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  We investigate the absorption distribution in a cylindrical gain medium that is pumped by a source of distributed laser diodes by means of a pump cavity developed from the edge-ray principle of nonimaging optics. The performance of this pumping arrangement is studied by using a nonsequential, numerical, three-dimensional ray-tracing scheme. A figure of merit is defined for the pump cavities that takes into account the coupling efficiency and uniformity of the absorption distribution. It is found that the nonimaging pump cavity maintains a high coupling efficiency with extended two-dimensional diode arrays and obtains a fairly uniform absorption distribution. The nonimaging cavity is compared with two other designs: a close-coupled side-pumped cavity and an imaging design in the form of a elliptical cavity. The nonimaging cavity has a better figure of merit per diode than these two designs. It also permits the use of an extended, sparse, two-dimensional diode array, which reduces thermal loading of the source and eliminates all cavity optics other than the main reflector.
• Blough, C. G., Bowen, J. P., Haun, N., Kindred, D. S., Koshel, R. J., Krill, D. M., Moore, D. T., Saxer, C. E., & Wang, D. Y. (1990). Effects of axial and radial gradients on Cooke triplets. Applied optics, 29(28), 4008-15.
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  This study investigates the role of gradient-index materials in the design of Cooke triplets for use as 35-mm format photographic objectives. Cooke triplet designs are presented with different types of gradient-index profiles. Both linear axial and shallow radial gradients are shown to provide effective control of spherical aberration and astigmatism. In particular, a Cooke triplet with a combination of both linear axial and radial gradients attains performance comparable to a six-element double Gauss lens. In virtually all cases, the use of gradient-index components improves the Cooke triplets' performance significantly.