Yuzuru Takashima

Interests

Research

• Lidar:o Laser beam steering device, MEMS-LiDAR, Automotive LiDAR, Single-chip LiDAR• AR Display:o Image steering and Foveation, Giga-pixel deisplay, Multiplexed Display, Near-to-eye display, Multi-perspective 3D display, On-chip 3D display, Holographic Display• Information optics:o Optical and holographic data storage• Optical system design engineeirng:o THz space optics, Camera optics• Optical engineering in general:o Digital Micromirror Device, MEMS phase light modulators, Computer Generated Holograms, Metrology, Photonics device design and modeling

Courses

Scholarly Contributions

Journals/Publications

• Takashima, Y. (2023). How students who don’t know anything about optics become optical engineers: Four years at the Wyant College of Optical Sciences. Kougaku, Optical Society of Japan, 52(12).
• Takashima, Y. (2023). Synthetic Aperture Scatter Imaging. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing.
• Brady, D. J., Wang, C., Takashima, Y., Schulz, T. J., & Hu, M. (2022). Snapshot ptychography on array cameras.. Optics express, 30(2), 2585-2598. doi:10.1364/oe.447499
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  We use convolutional neural networks to recover images optically down-sampled by 6.7 × using coherent aperture synthesis over a 16 camera array. Where conventional ptychography relies on scanning and oversampling, here we apply decompressive neural estimation to recover full resolution image from a single snapshot, although as shown in simulation multiple snapshots can be used to improve signal-to-noise ratio (SNR). In place training on experimental measurements eliminates the need to directly calibrate the measurement system. We also present simulations of diverse array camera sampling strategies to explore how snapshot compressive systems might be optimized.
• Takashima, Y. (2019). Holographic display with a wide viewing zone using a MEMS SLM without pixel pitch reduction. Optics Express.
• Takashima, Y. (2019). Multi-pulse laser beam steering with digital micro mirror device for time-of-flight lidar. Applied Optics.
• Takashima, Y. (2019). Wide-angle MEMS-based imaging lidar by decoupled scan axes. Applied Optics.
• Takashima, Y. (2021). Snapshot Ptychography on Array Cameras. Optics Express.
• Takashima, Y. (2021). Surface Measurement of a Large Inflatable Reflector in Cryogenic Vacuum. Photonics.
• Takashima, Y. (2022). Diffraction efficiency of MEMS phase light modulator, TI-PLM, for quasi continuous and multi-point beam steering. Micromachines.
• Takashima, Y. (2022). Modeling and characterization of OASIS inflatable primary antenna by dual modality metrology. Opt. Express.
• Takashima, Y. (2022). Optical design of the Orbiting Astronomical Satellite for Investigating Stellar Systems. J. Astron. Telesc. Instrum. Syst..
• Takashima, Y. (2022). Optical enhancement of diffraction efficiency of Texas Instruments Phase Light Modulator for beam steering in near infrared. Micromachines.
• Takashima, Y. (2022). Real-Time CGH Generation by CUDA-OpenGL Interoperability for Adaptive Beam Steering with a MEMS Phase SLM. Micromachines.
• Takashima, Y. (2022). Snapshot Ptychography on Array Cameras. Optics Express.
• Takashima, Y. (2022). Solid-state lidar by hybrid optical architecture with Digital Micromirror Devices and a 2D-MEMS mirror. Micromachines.
• Takashima, Y. (2022). Special Section Guest Editorial: MEMS Lidar. Journal of Optical Microsystems.
• Takashima, Y. (2022). Surface Measurement of a Large Inflatable Reflector in Cryogenic Vacuum. Photonics.
• Takashima, Y. (2022). Special Section Guest Editorial: MEMS Lidar. Journal of Optical Microsystems, 2(01). doi:10.1117/1.jom.2.1.011001
• Takashima, Y., Sirsi, S., Palisoc, A., Choi, H., Arenberg, J. W., Kim, D., & Walker, C. (2022). Optical design of the Orbiting Astronomical Satellite for Investigating Stellar Systems. Journal of Astronomical Telescopes, Instruments, and Systems, 8(03). doi:10.1117/1.jatis.8.3.034002
• Takashima, Y. (2020). Fast laser beam steering into multiple diffraction orders with a single digital micromirror device for time-of-flight lidar. Applied Optics, G239-G248.
• Takashima, Y. (2020). Holographic display having a wide viewing zone using a MEMS SLM without pixel pitch reduction. Optics Express.
• Takashima, Y. (2020). Review paper: imaging Lidar by Digital Micromirror Device. Optical Review.
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  Invited review paper
• Takashima, Y. (2020). Disruptive space telescope concepts, designs, and developments: OASIS and Nautilus. EOSAM 2020 EPJ Web of Conferences 238, 06001 (2020).
• Takashima, Y. (2020). Gigapixel and 1440-perspective extended-angle display by megapixel MEMS-SLM. Optics Letter, 5016-5019.
• Takashima, Y. (2020). Occlusion-capable optical-see-through near-eye display using a single digital micromirror device. Optics Letters, 3361-3364.
• Takashima, Y. (2020). Single-chip holographic beam steering for lidar by a digital micromirror device with angular and spatial hybrid multiplexing. Optics Express.
• Takashima, Y. (2020). Wide-angle MEMS-based imaging lidar by decoupled scan axes. Applied Optics.
• Takaki, Y., Takekawa, Y., Takashima, Y., & Nagahama, Y. (2019). Electronic Holographic Display Using MEMS-SLM with 40 Degree Viewing Zone. Proceedings of the International Display Workshops, 1017. doi:10.36463/idw.2019.1017
• Takashima, Y. (2019). Angular and spatial light modulation by single digital micromirror device for multi-image output and nearly-doubled étendue. Optics Express.
• Takashima, Y., & Nakamura, T. (2018). Design of discretely depth-varying holographic grating for image guide based see-through and near-to-eye displays. Optics Express.
• Takashima, Y., & Yamazaki, K. (2018). Time Differential Phase Detection Method for Robust Industrial Non-destructive Inspections. Japanese Journal of Applied Physics.
• Takashima, Y., Ozdemir, A., & Kurt, H. (2018). Analysis of the focusing crosstalk effects of broadband all-dielectric planar metasurface microlens arrays for ultra-compact optical device applications. OSA Continuum.
• Takashima, Y. (2017). Coherent Scattering Noise Reduction Method with Wavelength Diversity Detection for Holographic Data Storage System. Japanese Journal of Applied Physics.
• Takashima, Y. (2017). Coherent super resolution imaging via grating-based illumination. Applied Optics.
• Takashima, Y. (2017). Fast fabrication of polymer out-of-plane optical coupler by gray-scale lithography. Optics Express.
• Takashima, Y. (2017). Improvement of fill factor in pinhole-type integral imaging display using a retroreflector. Optics Express.
• Takashima, Y. (2017). Polarization independent high transmission large numerical aperture laser beam focusing and deflection by dielectric Huygens' metasurfaces. Optics Communications.
• Takashima, Y. (2017). Single Chip Lidar with Discrete Beam Steering by Digital Micromirror Device. Optics Express.
• Takashima, Y., Nakamura, Y., & Hoshizawa, T. (2016). Coherent Scattering Noise Reduction Method with Wavelength Diversity Detection for Holographic Data Storage System. Japanese Journal of Applied Physics.
• Takashima, Y., Ozdemir, A., Hayran, Z., & Kurt, H. (2016). Polarization independent high transmission large numerical aperture laser beam focusing and deflection by dielectric Huygens' metasurfaces. Optics Communications.
• Takashima, Y., Smith, B., Hellman, B., Gin, A., & Espinoza, A. (2016). Single Chip LIDAR with Discrete Beam Steering by Digital Micromirror Device. Optics Express.
• Takashima, Y., Takashima, Y., Goodman, J., Wilde, J., Elder, Y., Elder, Y., Wilde, J., & Goodman, J. (2016). Coherent super resolution imaging via grating-based illumination. Applied Optics.
• Takashima, Y., Widle, J., Elder, Y., & Goodman, J. (2016). Coherent super resolution imaging via grating-based illumination. Applied Optics.
• Takashima, Y., & Miller, B. (2016). Cavity techniques for holographic data storage recording. Optics Express.
• Takashima, Y., & Miller, B. (2016). Cavity-enhanced eigenmode and angular hybrid multiplexing in holographic data storage systems. Optics Express.
• Takashima, Y., & Miller, B. (2016). Enabling energy-efficient holographic optical storage for cold data. SPIE News Room.
• Takashima, Y., & Miller, B. E. (2016). Cavity enhanced image recording for holographic data storage. Proceedings of SPIE, 9959. doi:10.1117/12.2237078
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  We report the experimental verification of cavity enhanced recording of image bearing holograms in Fe:LiNbO3 with a 532 nm wavelength, CW, single mode, DPSS, Nd:YAG, laser with a cavity on the reference arm. Diffraction efficiency evolution was monitored via pseudo-phase-conjugate readout during recording. Additionally, optimization of grating strengths in standing wave cavity writing is explored, and a means of eliminating unwanted gratings via quarter wave plates with isotropic recording media is proposed.
• Takashima, Y., Ishii, T., Hoshizawa, T., & Shimada, K. (2016). Modeling and analysis of vibration effects on signal quality for angular multiplexed holographic data storage. Japanese Journal of Applied Physics.
• Takashima, Y., & Miller, B. E. (2015). Enhancement of data rates by single and double cavity holographic recording. Proceedings of SPIE, 9587. doi:10.1117/12.2187253
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  To satisfy the growing need for faster archival data storage and retrieval, we proposed an improvement to the read and write data transfer rates of Holographic Data Storage Systems (HDSS). Conventionally, reading and writing of data utilize only a fraction of the available light. Our techniques apply a resonator cavity to the readout and recording of holograms so that more of the available light is used. Functionally, more power is used than what is provided without violating energy conservation. Thus, data rates and/or capacities can be increased due to enhanced power. These improvements are also inversely related to the diffraction efficiency of a hologram, which makes these cavity enhanced techniques well suited to HDSS where large numbers of multiplexed holograms require low diffraction efficiencies. Previously, we presented the theory of cavity enhanced HDSS, the experimental effect of enhancement on readout, and the lack of effects on Bragg Selectivity. We have now formalized the enhancement in writing power and experimentally evaluated the improvement in writing speed over conventional means for writing a single plane wave hologram in Fe:LiNbO3 with a 532 nm wavelength, CW, single mode, DPSS, Nd:YAG, laser with a cavity on one of the writing arms. The diffraction efficiency was read during the recording by using a 632.8 nm wavelength HeNe Laser. We found that the enhancement of recording power for this configuration asymptotically approaches a factor of two, while the use of cavities in both writing arms provides a power enhancement which is limited only by the losses in the cavities. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
• Takashima, Y., Ishii, T., & Shimada, K. (2015). Analysis of vibration effects on holographic data storage system. Jpn. J. Appl. Phys..
• Takashima, Y., Ishii, T., Shimada, K., & Hoshizawa, T. (2015). New optical modeling and optical compensation for mechanical instabilities on holographic data storage system using time averaged holography. Jpn. J. Appl. Phys..
• Zaverton, M., Wang, S., Takashima, Y., Summitt, C., Milster, T. D., Johnson, L., & Ge, T. (2015). Process optimization for a 3D optical coupler and waveguide fabrication on a single substrate using buffer coat material. Proceedings of SPIE, 9374. doi:10.1117/12.2080425
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  We have developed a hybrid lithography process necessary to fabricate a vertical optical coupler and an array of waveguide structures using the same buffer coat material on a single substrate. A virtual vernier scale built into the process enables precise alignment of both structures.
• Takashima, Y. (2014). Evaluation of channel capacities of OAM-based FSO link with real-time wavefront correction by adaptive optics. Optics Express.
• Takashima, Y. (2014). Optical design in high density and high capacity multi-layer data storage system. Front. Optelectron.
• Takashima, Y., & Hesselink, L. (2012). Design and implementation of multi-layer and multi-bit micro holographic optical data storage employing blue lasers. Proceedings of SPIE - The International Society for Optical Engineering, 8486.
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  Abstract: A zoom objective lens for a multi-layer optical recording has been designed. A newly proposed optical power arrangement enables varying back focal length while focal length invariant by a linear movement of single zooming component. The zoom lens is implemented into multi-layer and multi-bit holographic recording system employing 405 nm blue lasers. © 2012 SPIE.
• Cheng, Y., Takashima, Y., Maldonado, J. R., Scipioni, L., Ferranti, D., Pianetta, P. A., Hesselink, L., & Pease, R. F. (2011). Sub-15 nm photo-electron source using a nano-aperture integrated with a nano-antenna. 2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011.
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  Abstract: We propose a nano-scale C-aperture nano-tip photo-electron source with a CsBr photo-cathode. We fabricated the structure and estimated the optical spot available in the CsBr thin film with photoresist exposure. © 2011 OSA.
• Cheng, Y., Takashima, Y., Maldonado, J. R., Scipioni, L., Ferranti, D., Pianetta, P. A., Hesselink, L., Pease, R. F., Cheng, Y., Takashima, Y., Maldonado, J. R., Scipioni, L., Ferranti, D., Pianetta, P. A., Hesselink, L., Pease, R. F., Cheng, Y., Takashima, Y., Maldonado, J. R., , Scipioni, L., et al. (2011). Sub-15 nm photo-electron source using a nano-aperture integrated with a nano-antenna. Optics InfoBase Conference Papers.
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  Abstract: We propose a nano-scale C-aperture nano-tip photo-electron source with a CsBr photo-cathode. We fabricated the structure and estimated the optical spot available in the CsBr thin film with photoresist exposure. © OSA/CLEO 2011.
• Cheng, Y., Takashima, Y., Yuen, Y., Hansen, P. C., Leen, J. B., & Hesselink, L. (2011). Ultra-high resolution resonant C-shaped aperture nano-tip. Optics Express, 19(6), 5077-5085.
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  PMID: 21445142;Abstract: We report a new optical near-field transducer comprised of a metallic nano-antenna extending from the ridge of a C-shaped metallic nano-aperture. Finite-difference time domain simulations predict that the C-aperture nano-tip (CAN-Tip) provides high intensity (650x), high optical resolution (∼λ/60), and background-free near-field illumination at a wavelength of 980 nm. The CAN-Tip has an aperture resonance and tip antenna resonance which may be tuned independently, so the structure can be made resonant at ultraviolet wavelengths without being unduly small. This near-field optical resolution of 16.1 nm has been experimentally confirmed by employing the CAN-Tip as an NSOM probe. © 2011 Optical Society of America.
• Takashima, Y., Hesselink, L., Liu, J., & Yang, L. (2011). Novel optical architecture for high capacity and high data transfer rate holographic data storage. 2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011.
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  Abstract: A novel optical system architecture employing local holographic recording with a pico-second pulsed fiber laser and a small page size SLM has the potential towards realizing compact, high capacity and high data transfer rate optical storage. © 2011 OSA.
• Takashima, Y., Hesselink, L., Liu, J., Yang, L., Takashima, Y., Hesselink, L., Liu, J., Yang, L., Takashima, Y., Hesselink, L., Liu, J., & Yang, L. (2011). Novel optical architecture for high capacity and high data transfer rate holographic data storage. Optics InfoBase Conference Papers.
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  Abstract: A novel optical system architecture employing local holographic recording with a pico-second pulsed fiber laser and a small page size SLM has the potential towards realizing compact, high capacity and high data transfer rate optical storage. © OSA/ CLEO 2011.
• Wilde, J. P., Takashima, Y., Goodman, J. W., & Eldar, Y. C. (2011). Grating-enhanced coherent imaging. Ntm. doi:10.1364/ntm.2011.nma3
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  We describe a coherent imaging technique that utilizes a diffraction grating placed near the object to alias high spatial frequency information through the imaging system pupil. Linear signal processing is used to reconstruct high-resolution images.
• Yen, S., Takashima, Y., Tendulkar, M., Jameson, J. R., Nishi, Y., & Kazovsky, L. G. (2011). Quasi passive optical switch based on transition metal oxide device. 2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011.
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  Abstract: We propose optical switch architecture based on transition metal oxide material. It use electrical field to change oxygen vacancy distribution and its optical property such as absorption coefficient. We demonstrate the absorption coefficient of such device can be latched in binary state, which is useful for optical networking and interconnect applications. © 2011 OSA.
• Takashima, Y., & Hesselink, L. (2010). Design and implementation of recording and readout system for micro-holographic optical data storage. Proceedings of SPIE - The International Society for Optical Engineering, 7786.
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  Abstract: A lens design having constant working distance while having variable recording depth for micro holographic data storage system has been proposed. Variation of focal length is suppressed for the entire depth within 1% which enables focusing and tracking servoing without changing servo parameters. © 2010 SPIE.
• Takashima, Y., Cheng, Y., Hansen, P., Yuen, Y., Hesselink, L., Pease, R. F., Maldonado, J. R., & Pianetta, P. A. (2010). 8.1: Experimental verification of a λ/50 optical spot size of a C-aperture nano antenna tip for photo-electron emitter applications. 23rd International Vacuum Nanoelectronics Conference, IVNC 2010, 113-114.
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  Abstract: We propose a photo-electron emitter structure whose electron beam size is 20nm using CsBr photo-emission layer and a novel nano-optical antenna structure. The optical spot size of 20nm has been experimentally demonstrated. © 2010 IEEE.
• Takashima, Y., Koc, A., & Hesselink, L. (2010). Systematic analysis of the validity regions of scalar diffraction integral and angular spectrum method. IEEE Transactions on Biomedical Engineering. doi:10.1364/biomed.2010.jma4
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  A systematic comparison of the accuracies of scalar diffraction integral and angular spectrum method with respect to FDTD are done. Validity regions of the methods are derived and optimal method for each region is determined.
• Takashima, Y., Shi, X., Ross, F., Ren, Z., Ostroverkhov, V. P., Lawerence, B., & Boden, E. P. (2010). Micro-Holographic Data Storage: Materials and Systems. The Review of Laser Engineering, 38(5), 349-355. doi:10.2184/lsj.38.349
• Takashima, Y., & Hesselink, L. (2009). Designs and tolerances of numerical aperture 0.8 objective lenses for page-based holographic data storage systems. Japanese Journal of Applied Physics, 48(3 PART 2).
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  Abstract: A two-element aspheric objective lens having numerical aperture (NA) of 0.8 has been designed for media interchangeable holographic recordings. Lens design tolerance of offence against the sine condition and lens aberrations of object and reference beams have been formalized by coupled wave theory and related to diffraction efficiency of holograms. An optimum first-order power arrangement of objective lenses having two air-spaced elements has been identified by minimizing fifth-order aberrations and is further optimized ray-tracebased optimization code. Within tolerances criteria required for media-interchangeable systems, the design has demonstrated high NA of 0.8 with long working distance of 20% of the focal length. © 2009 The Japan Society of Applied Physics.
• Takashima, Y., & Hesselink, L. (2007). Lens Designs of High NA Objectives for Page-based Holographic Data Storage Systems. Frontiers in Optics. doi:10.1364/fio.2007.pdp_a2
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  High NA (0.7 ~ 0.8) objective lens in which both object and pupil aberrations are compensated for are designed in two-element configurations, and are usable for a combination of holographic and surface recordings.
• Takashima, Y., Orlov, S., & Hesselink, L. (2007). Lens designs for page-based holographic storage systems. Proceedings of SPIE - The International Society for Optical Engineering, 6620.
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  Abstract: A single meniscus aspherical lens and air-spaced spherical lenses having negative and positive powers are identified as minimum aberration configurations for page-based holographic recording systems. Further correction of pupil aberrations makes the lens system usable both for holographic and for surface recording, and the lens is realizable by using two air-spaced apsherics. Two air-spaced apsherics can attain high an imaging NA of 0.7 for holographic recording only, and an NA of 0.45 for a combination of holographic and surface recording.
• Takashima, Y., & Hesselink, L. (2006). En-squared power based optical design for page-based holographic storage systems. Proceedings of SPIE - The International Society for Optical Engineering, 6342 I.
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  Abstract: The Fourier transform lens consisting of an aspherical element is analyzed in terms of the supportable number of pixels by formalizing an en-squared-power ratio as a function of the Nyquist aperture ratio and aberrations. © 2006 SPIE-OSA.
• Takashima, Y., & Hesselink, L. (2006). Media tilt tolerance of bit-based and page-based holographic storage systems. 2006 Optical Data Storage Topical Meeting - Post Deadline Papers, 221-223.
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  Abstract: Under a constraint of the same diffraction efficiency per pixel/detector and media dynamic range, a bit-based holographic storage has a larger media tilt tolerance compared to a page-based system with relatively large page size. © 2006 IEEE.
• Takashima, Y., & Hesselink, L. (2006). Media tilt tolerance of bit-based and page-based holographic storage systems. Optics Letters, 31(10), 1513-1515.
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  PMID: 16642156;Abstract: Tilt tolerance of media is compared for bit-based and page-based holographic storage systems having an equal diffraction efficiency per bit detector, dynamic range of the medium, and surface recording density. We have formalized the diffraction efficiency degradation caused by aberrations of a reconstructing reference beam induced by tilt of the medium, using a coupled wave theory in the Fourier domain. The bit-based holographic storage system has a larger media tilt tolerance compared with a page-based system with relatively large page size. © 2006 Optical Society of America.
• Takashima, Y., & Hesselink, L. (2006). Media tilt tolerance of bit-based and page-based holographic storage systems. Proceedings of SPIE - The International Society for Optical Engineering, 6282.
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  Abstract: Tilt tolerance of media is compared for bit-based and page-based holographic storage systems having an equal diffraction efficiency per bit detector, dynamic range of the medium and surface recording density. We have formalized the diffraction efficiency degradation caused by aberrations of a reconstructing reference beam induced by tilt of the medium, using a coupled wave theory in the Fourier domain. The bit-based holographic storage system has a larger media tilt tolerance compared to a page-based system with relatively large page size.
• Orlov, S. S., Phillips, W., Bjornson, E., Takashima, Y., Sundaram, P., Hesselink, L., Okas, R., Kwan, D., & Snyder, R. (2004). High-transfer-rate high-capacity holographic disk data-storage system. Applied Optics, 43(25), 4902-4914.
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  PMID: 15449477;Abstract: We describe the design and implementation of a high-data-rate high-capacity digital holographic storage disk system. Various system design trade-offs that affect density and data-rate performance are described and analyzed. In the demonstration system that we describe, high-density holographic recording is achieved by use of high-resolution short-focal-length optics and correlation shift multiplexing in photopolymer disk media. Holographic channel decoding at a 1-Gbit/s data rate is performed by custom-built electronic hardware. A benchmark sustained optical data-transfer rate of 10 Gbits/s has been successfully demonstrated. © 2004 Optical Society of America.
• Orlov, S. S., Bjornson, E., Phillips, W., Takashima, Y., Li, X., & Hesselink, L. (2000). High transfer rate (1 Gbit/sec) high-capacity holographic disk digital data storage system. Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, 190-191.
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  Abstract: The holographic disk approach allows for an easy access to a large area of data storage media, and therefore, is more suitable for high capacity applications. The holographic disks storage system developed within DARPA Holographic Data Storage Systems consortium includes hardware implemented channel decoding providing high transfer rate (1 Gbit/sec) and high capacity storage (>100 Gbit per 6.5 disk).
• Takashima, Y., Kitagawa, T., Amano, A., Hata, Y., Yamagata, Y., & Higuchi, T. (1997). Fabrication and testing of a blazed holographic optical element. Proceedings of SPIE - The International Society for Optical Engineering, 3135, 188-196.
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  Abstract: A blazed holographic optical element (HOE) has developed with injection molding technique. It is able to function as a beam splitter and aberration generator for focusing error detection of optical pick up head for optical storage system. The die was made by 4 axis controlled ultra precision cutting machine using single crystalline diamond cutting tool We carried out fabrication error estimation caused by cutting and injection, and derived adequate tolerance budget. The efficiency of HOE defined y the product of 0th and 1st order diffraction efficiency was measured by knife-edge method. We attained high efficiency of 15.5% which is close to theoretical limit. The efficiency is about 1.5 times as that of conventional non- blazed HOE. ©2004 Copyright SPIE - The International Society for Optical Engineering.
• Yamagata, Y., Higuchi, T., Takashima, Y., & Ueda, K. (1996). Fabrication of micromechanical and optical components by ultraprecision cutting. Proceedings of SPIE - The International Society for Optical Engineering, 2881, 148-157.
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  Abstract: Micro mechanical parts and optical parts are fabricated through ultra precision cutting technique. The precision cutting technique has been considered to be inappropriate for micro parts fabrication of the micrometer order. Our ultra precision cutting technique with sub-micrometer cutting depth made it possible to fabricate 3D micro mechanical parts and micro optical parts. Following micro mechanical parts are fabricated: 10 micrometer shaft by lathe machining, 100 micrometer screw with 20 micrometer pitch thread, and 50 micrometer thickness lever made by stainless steel. Also it was able to fabricate micro optical parts such as holographic optical element with sawtooth cross section and pitch of 3 micrometer. The fabrication was carried out with newly developed ultra precision machine tool with X, Y, Z linear axis and one rotational axis using single crystalline diamond cutting tool. Those linear axis are controlled through hologram scale with 1 nm resolution. The fabrication process by precision cutting has proved to be faster and more precise compared to the lithography and etching method.

Proceedings Publications

• Takashima, Y. (2023). Beam and image steering towards solid-state lidar and all-day wearable AR near-to-eye display. In International Symposium on Imaging, Sensing, and Optical MemoryThe Laser Display and Lighting Conference (ISOM 2023).
• Takashima, Y. (2023). Beam tracking and image steering by TI PLM based on camera input for lidar and AR applications. In SPIE Photonics West.
• Takashima, Y. (2023). Evaluation of pulsed laser sources for a solid-state diffractive image steering and foveation by Texas Instruments Digital Micromirror Device. In SPIE AR/VR/MR (2023).
• Takashima, Y. (2023). Field-of-view expansion via diffractive image steering and prism array. In SPIE AR/VR/MR 2023.
• Takashima, Y. (2023). Image Steering by MEMS SLM for Near-to-eye AR Display Engin. In The 30h International Display Workshops (IDW ’23), Niigata, Japan.
• Takashima, Y. (2023). Lidar and Near-to-eye AR Display by Angular and Spatial Light Modulation with MEMS SLM. In The Laser Display and Lighting Conference (LDC 2023).
• Takashima, Y. (2023). Metrology in meter class inflatable antenna for a space observatory. In Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems IV, SPIE Optics and Photonics.
• Takashima, Y. (2023). Multi-Domain Multiplexing for Large Field of View in Near-to-Eye Displays. In ODS 2023: Industrial Optical Devices and Systems, part of SPIE Optical Engineering + Applications.
• Takashima, Y. (2023). Solid-state lidar and all-day-wearable AR display with MEMS SLM. In SPIE Digital Optical Technologies, (DOT 2023).
• Takashima, Y. (2023). Wide Field of View Real-time flash DMD-Lidar with 2D Multi-Pixel Photon Counter. In SPIE Photonics West.
• Choi, H., Takashima, Y., Luo, C., Guan, J., Hong, Y., Evans, E., Lee, T., Liu, P., Deng, X., Smith, B., Rodriguez, J., Hellman, B., & Kang, E. (2022). Large etendue solid-state-lidar with MEMS-resonant mirror assisted diffractive beam steering by digital micromirror device. In SPIE.
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  By combining a Micro Electro Mechanical System based resonant mirror and a Digital Micromirror Device, we demonstrated a large scan angle, fast scan rate, and high resolution beam steering for the lidar applications. The proposed optical architecture preserves a large Etendue of DMD-based diffractive beam steering with a synchronized short pulsed laser to transition of micromirror array while increasing angular resolution.
• Takashima, Y. (2020, April 2020). Lidar and AR Displays by MEMS-based Angular and Spatial Light Modulation. In 12th International Conference on Optics-photonics Design and Fabrication (ODF 2020).
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  Meeting postponed to June, 2021 due to COVID19 travel restriction
• Takashima, Y. (2020, Sep 2020). MEMS Imaging Lidar. In ICO-OWLS-2020.
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  Meeting postponed to Sep. 17, 2021 due to COVID19 travel restriction.
• Takashima, Y. (2022). Angular and Spatial Light Modulation for Lidar and AR display. In ISOM 2022.
• Takashima, Y. (2022). Beam and Image Steering for Mobility Photonics Application of MEMS SLM for solid-state lidar and AR display. In The 2nd Mobility Photonics Research Meeting, Optoelectronics Industry and Technology Development Association (OITDA) Japan.
• Takashima, Y. (2022). CUDA-OpenGL GPU-based real time beam tracking by MEMS phase SLM. In SPIE Photonics West Emerging Digital Micromirror Device Based Systems and Applications XIV.
• Takashima, Y. (2022). DMD-based diffractive FOV expansion for real-time flash lidar with 2D multi-pixel photon counter. In Industrial Optical Devices and Systems (ODS) SPIE Optics and Photonics.
• Takashima, Y. (2022). Diffraction efficiency of MEMS Phase Light Modulator for quasi continuous beam steering. In SPIE Photonics West Emerging Digital Micromirror Device Based Systems and Applications XIV.
• Takashima, Y. (2022). Large Etendue laser beam steering by 2D MEMS resonant mirror and Digital Micromirror Device for time-of-flight lidar and AR display. In Industrial Optical Devices and Systems (ODS) SPIE Optics and Photonics.
• Takashima, Y. (2022). Large Etendue solid-state-lidar with MEMS-resonant mirror assisted diffractive beam steering by Digital Micro Mirror devices. In SPIE Photonics West Emerging Digital Micromirror Device Based Systems and Applications XIV.
• Takashima, Y. (2022). Optical enhancement of diffraction efficiency of Texas Instrument Phase Light Modulator by Talbot imaging-based pixel matching for infrared lidar beam steering. In SPIE Photonics West Emerging Digital Micromirror Device Based Systems and Applications XIV.
• Takashima, Y. (2022). Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS): A Paradigm Shift in Realizing Large Space Apertures. In SPIE Space Telescopes and Instrumentation 2022: Optical, Infrared, and Millimeter Wave, SPIE Astronomical Telescopes + Instrumentation.
• Takashima, Y. (2022). Unlocking the potential of TI-DMD for AR display and lidar engine: Image and beam steering by MEMS SLMs. In ICO-OWLS-2022.
• Takashima, Y. (2022). Volume holographic grating for wavelength multiplexed field-of-view expansion. In Optical Architectures for Displays and Sensing in Augmented, Virtual, and Mixed Reality (AR, VR, MR) III, SPIE AR/VR/MR.
• Takashima, Y. (2022). Wavelength multiplexed field of view expansion for high-resolution near-to-eye displays. In Optical Architectures for Displays and Sensing in Augmented, Virtual, and Mixed Reality (AR, VR, MR) III, SPIE AR/VR/MR.
• Takashima, Y. (2022). SALTUS Probe Class Space Mission: Enabled by 20-m Inflatable Mirror. In CLEO 2022.
• Takashima, Y. (2021). All reflective THz telescope design with a 20m inflatable primary antenna for Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS) mission. In Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems III, SPIE Optics and Photonics.
• Takashima, Y. (2021). Analysis of diffraction efficiency of TI-PLM and its potential in bean steering. In Industrial Optical Device and Systems, SPIE Optics and Photonics.
• Takashima, Y. (2021). Analytical and finite element analysis tool for nonlinear membrane modeling and inflatable antenna design. In Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems III, SPIE Optics and Photonics.
• Takashima, Y. (2021). Design and performance of the Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS) primary reflector. In Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems III, SPIE Optics and Photonics.
• Takashima, Y. (2021). Gigapixel 1440-perspective display by sub-megapixel DMD. In SPIE AR/VR/MR 2021, SPIE Photonics West.
• Takashima, Y. (2021). Inflatable Space Terahertz Optics Technology. In XLIV OSI Symposium on Frontiers in Optics and Photonics 2021.
• Takashima, Y. (2021). Mid to high frequency characterization of inflatable membrane optics. In Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems III, SPIE Optics and Photonics.
• Takashima, Y. (2021). Occlusion-capable AR near to eye display using a single digital micromirror device. In SPIE Photonics West.
• Takashima, Y. (2021). Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS) Following the Water Trail from the Interstellar Medium to Oceans. In Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems III, SPIE Optics and Photonics.
• Takashima, Y. (2021). Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS) observatory design. In Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems III, SPIE Optics and Photonics.
• Takashima, Y. (2021). Parametric design study of all reflective 20m telescope with an inflatable primary antenna for Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS. In Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems III, SPIE Optics and Photonics.
• Takashima, Y. (2021). Pre-flight Optical Metrology for Varifocal Pneumatic Terahertz Antenna. In Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems III, SPIE Optics and Photonics.
• Takashima, Y. (2021). Preface: Enablers for DX (Digital Transformation), can AR display and automotive lidar be next optical data storage industry?. In 71st symposium of Optical Design Research group.
• Takashima, Y. (2021). Pulsed illumination driver with intensity control and RGB mixing capabilities for high-resolution near-eye display. In SPIE AR/VR/MR 2021, SPIE Photonics West.
• Takashima, Y. (2021). Single-chip DMD-based hybrid holographic beam steering for lidar. In Emerging Digital Micromirror Device Based Systems and Applications XIII, SPIE Photonics West.
• Takashima, Y. (2021). Stability of diffractive beam steering by a Digital Micromirror Device. In Emerging Digitalmicromirrors Applications, SPIE Photonics West.
• Takashima, Y. (2021). Stressed Deformable Reflector Design and Pneumatic Membrane Antenna for Cryogenic Thermal Vacuum Chamber Testing. In Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems III, SPIE Optics and Photonics.
• Choi, H., Walker, C. K., Takashima, Y., Sirsi, S., Phan, A. V., Kim, D. W., & Chandra, A. (2020). Thermally formed inflatable reflectors for space telescopes. In SPIE.
  More info

  Imaging distant objects with increasing spatial resolution is instrumental towards furthering space exploration abilities. Telescopic imaging of exoplanets and other objects requires mirrors with large surfaces which when used at terahertz frequencies can further capture object chemistry, mass structure and dynamics. Membrane mirrors could lead to a dramatic scale up in size of telescope mirrors deployed on orbit. Large membrane reflectors built in the past have had a primary challenge of uncontrolled inflation dynamics and surface shape. A major contribution to such inaccuracies has been attributed to manufacturing techniques employed. The surface shape attained by a tensioned membrane has been described as an oblate spheroid or Hencky surface. Traditionally built out of smaller gore units, membrane mirrors tend to attain faceted final shapes that deviate from the intended. They have unreliable and unrepeatable final surface shapes. This makes the design of corrective optics difficult. Further, complex assembly jigs are required for the precise manufacture of such membrane units. A repeatable and scalable manufacturing method is required to harness the advantages offered by membrane reflectors. Our present work is focused on thermally formed membrane reflectors. This involves heating a whole flat membrane close to its glass-transition region followed by pressurization at a constant fixed temperature. The intent is to induce plastic deformation of the membrane causing a retention of induced curvature when cooled down. This method eliminates breaking down the membrane structure into smaller gore units and can be scaled over to vast membrane sizes. An experimental set-up has been designed and built to thermally form a 1-meter diameter Mylar membrane reflector and conduct shape measurement on its surface. We present development efforts in the design, manufacture and surface shape measurement of thermally formed reflectors. The results are being used to validate thermo-structural simulations conducted on the expected membrane surface behavior. Further analysis is underway to understand optimal circumferential stress distributions to improve the reliability of obtained membrane shapes. Our work contributes towards an understanding of key design variables in the development of tensioned thermally formed membrane reflectors that can provide a potential pathway towards dramatic scale up in size of such mirrors.
• Choi, H., Walker, C. K., Takashima, Y., Sirsi, S., Phan, A., Kim, D. W., & Chandra, A. (2020). Thermally formed inflatable reflectors for space telescopes. In 2020 IEEE Aerospace Conference.
  More info

  Imaging distant objects with increasing spatial resolution is instrumental towards furthering space exploration abilities. Telescopic imaging of exoplanets and other objects requires mirrors with large surfaces which when used at terahertz frequencies can further capture object chemistry, mass structure and dynamics. Membrane mirrors could lead to a dramatic scale up in size of telescope mirrors deployed on orbit. Large membrane reflectors built in the past have had a primary challenge of uncontrolled inflation dynamics and surface shape. A major contribution to such inaccuracies has been attributed to manufacturing techniques employed. The surface shape attained by a tensioned membrane has been described as an oblate spheroid or Hencky surface. Traditionally built out of smaller gore units, membrane mirrors tend to attain faceted final shapes that deviate from the intended. They have unreliable and unrepeatable final surface shapes. This makes the design of corrective optics difficult. Further, complex assembly jigs are required for the precise manufacture of such membrane units. A repeatable and scalable manufacturing method is required to harness the advantages offered by membrane reflectors. Our present work is focused on thermally formed membrane reflectors. This involves heating a whole flat membrane close to its glass-transition region followed by pressurization at a constant fixed temperature. The intent is to induce plastic deformation of the membrane causing a retention of induced curvature when cooled down. This method eliminates breaking down the membrane structure into smaller gore units and can be scaled over to vast membrane sizes. An experimental set-up has been designed and built to thermally form a 1-meter diameter Mylar membrane reflector and conduct shape measurement on its surface. We present development efforts in the design, manufacture and surface shape measurement of thermally formed reflectors. The results are being used to validate thermo-structural simulations conducted on the expected membrane surface behavior. Further analysis is underway to understand optimal circumferential stress distributions to improve the reliability of obtained membrane shapes. Our work contributes towards an understanding of key design variables in the development of tensioned thermally formed membrane reflectors that can provide a potential pathway towards dramatic scale up in size of such mirrors.
• Kim, D., Walker, C. K., Apai, D., Milster, T. D., Takashima, Y., Schneider, G., Kim, Y., Fellows, C., Zhang, Y., Gaspar, A., Smith, S., Crowe, D., Bixel, A., O'Dougherty, S., Sirsi, S., Chandra, A., Phan, A., Wang, Z., Purvin, K., , Quach, H., et al. (2020, August 2020). Disruptive space telescope concepts, designs, and developments: OASIS and Nautilus. In Topical Meeting 6 – Frontiers in Optical Metrology (EOS Annual Meeting 2020), 238 (2020), 06001.
• Takashima, Y. (2020, Aug 2020). Full-Aperture Optical Metrology for Large, Ultralightweight Membrane Mirrors. In Optical Manufacturing and Testing XIII at SPIE Optics Photonics San Diego (2020).
• Takashima, Y. (2020, Aug. 2020). Controlling transitional time of DMD mirror array by physical and electrical methods. In SPIE Optics and Photonics, Proc. SPIE 11500, ODS 2020: Industrial Optical Devices and Systems, 115000D (28 August 2020).
• Takashima, Y. (2020, Feb. 2020). Angular and spatial light modulation by single digital micromirror device for display applications. In SPIE Photonics West AR/VR/MR 2020 (AVR2020)..
• Takashima, Y. (2020, March 2020). Angular and spatial light modulation by single digital micromirror device for beam and pattern steering. In SPIE Photonics West (SPIE OPTO-PW20O) (2020).
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  Best Student Paper Award
• Takashima, Y. (2020, May 2020). Lidar Optical Architectures with Digital Micromirror Devices. In CLEO 2020.
• Takashima, Y. (2020, May 2020). Occlusion-capable optical-see-through near-eye display using single digital micromirror device. In OSA Topical Meeting on Digital Holography.
• Takashima, Y. (2020, May 2020). Reduction of Effective Pixel Pitch of Digital Micromirror Device for Lidar Transmitter and Receiver. In CLEO 2020 ATTR: Optical Technologies for Autonomous Cars and Mobility I (AF1M.4.).
• Takashima, Y. (2020, Sep 2020). Design, Optimization, and De-sensitizing of Radiation Hard Wide Angle Space-mission Camera. In Frontiers in Optics 2020, Washington DC (2020).
• Takashima, Y. (2020, Sep 2020). MEMS-based Angular and Spatial Light Modulation for Lidar and AR Displays. In Frontiers in Optics 2020, Washington DC (2020).
• Takashima, Y., & Katayama, R. (2020). Opening remarks to ODS 2020: Industrial Optical Devices and Systems. In ODS 2020: Industrial Optical Devices and Systems, 11500.
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  The ODS has been held as part of SPIE Optics + Photonics since 2014. Formerly, the scope of ODS was optical data storage, but since 2018, it has been extended to industrial optical devices and systems. The new scope includes emerging industrial domains such as automotive, IoT, big data, healthcare, security, etc. We are pleased that the number of papers is increasing in the last three years, and that their areas are expanding from traditional optical data storage to various industrial optical devices and systems. This means that the new scope of ODS has been recognized by optics research and development community in industry. We hope that all of you will enjoy this conference and help make it more attractive in the future.
• Takashima, Y. (2019, August). High-speed LIDAR by multi-order laser beam steering with digital micromirror device. In SPIE Optics and Photonics 2019.
• Takashima, Y. (2019, December). Occlusion Capable Near-Eye Display for Augmented Reality using Single Digital Micromirror Display. In The 9th Korea-Japan Workshop on Digital Holography and Information Photonics.
• Takashima, Y. (2019, Fall). Design of discretely depth-varying holographic grating for image guide based see-through and near-to-eye displays. In Imaging Sensing and Optical Memory (ISOM 2019).
• Takashima, Y. (2019, Fall). Imaging LIDARs by Digital Micromirror Device. In Imaging Sensing and Optical Memory (ISOM 2019).
• Takashima, Y. (2019, Fall). Thermally formed inflatable reflectors for space telescopes. In IEEE Aerospace Conference 2019.
• Takashima, Y. (2019, June). Proposal of holographic display using MEMS-SLM and pulse modulated laser. In OSA Digital Holography 2019.
• Takashima, Y. (2019, May). Multi-order Laser Beam Steering with Digital Micro Mirror Device for High-speed LIDARs. In CLEO 2019.
• Takashima, Y. (2019, September). Angular and Spatial Light Modulation by Single Digital Micromirror Device for Multi-Image Output and Nearly-Doubled Étendue. In Frontiers in Optics + Laser Science, 15-19 September 2019.
• Takashima, Y., & Katayama, R. (2019). ODS 2019: Industrial Optical Devices and Systems. In ODS 2019: Industrial Optical Devices and Systems, 11125.
• Takashima, Y., & Katayama, R. (2018). Optical Data Storage 2018: Industrial Optical Devices and Systems. In Optical Data Storage 2018: Industrial Optical Devices and Systems, 10757.
• Takashima, Y., & Nakamura, T. (2018, August). Physical and geometrical hybrid design of two-layer and depth-chirped holographic image guide for see-through glass type head mounted display. In SPIE Optics and Photonics.
• Takashima, Y., Chen, G., Hellman, B., Rodriguez, J., Smith, B., & Gin, A. (2018, August). Light Recycling Techniques for Efficient Beam Steering by Digital Micromirror Device. In SPIE Optics and Photonics.
• Takashima, Y., Hellman, B., Smith, B., Rodriguez, J., Gin, A., Winkler, P., & Kim, Y. (2018, August). Single detector imaging lidar by digital micromirror device for large field-of-view and mid-range mapping applications. In SPIE Optics and Photonics.
• Takashima, Y., Rodriguez, J., Chen, G., Smith, B., Gin, A., Espinoza, A., Winkler, P., Perl, C., Luo, C., Kang, E., Kim, Y., Choi, H., & Kim, D. (2018, November). MEMS-based Imaging LIDAR. In OSA E2.
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  Invited Talk
• Takashima, Y., Rodriguez, J., Kang, E., Hellman, B., Chen, G., Smith, B., Gin, A., & Espinoza, A. (2018, August). Beam steering by digital micro-mirror device for multi-beam and single-chip LIDAR. In SPIE Optics and Photonics.
• Takashima, Y., Rodriguez, J., Smith, B., Hellman, B., Gin, A., & Espinoza, A. (2018, March). Multi-beam and single-chip LIDAR with discrete beam-steering by digital micromirror device. In SPIE Photonics West.
• Takashima, Y., Sanaka, K., Takeuchi, M., & Suzuki, R. (2018, August). Recording arbitrary polarization states on photorefractive media. In SPIE Optics and Photonics.
• Takashima, Y., Yamaz, N., Ozdemir, A., Bagci, F., & Kurt, H. (2018, August). All-dielectric metasurface lenses for focal plane arrays operating in mid-wave infrared spectrum. In SPIE Optics and Photonics.
• Yilmaz, N., Takashima, Y., Ozer, A., Ozdemir, A., Kurt, H., Giden, I. H., & Bagci, F. T. (2018). Tunable metasurfaces with liquid crystals. In Metamaterials XI, 10671.
  More info

  Intensive researches in the area of metasurfaces have provided a new insight to obtain flat and compact optical systems. In this letter, we numerically show that, highly efficient tunable beam steering effect in transmission mode is achieved at wavelength λ = 550 nm using nematic liquid crystals (LCs) infiltrated into double sided metasurfaces. Using the electrooptical feature of LCs, the phase profile of the metasurfaces is controlled and thus, the transmitted beam is deflected within the range from -15° to 15° steering angles. Transparent dielectric materials are used in the designed structure that provides highly efficient beam-steering; the corresponding transmission efficiency is above 83% in the visible spectrum, which is another superiority of the proposed hybrid tunable structure over present plasmonic/metamaterial approaches. The designed metasurface still preserves its beam deflection property covering the visible spectrum and hence, such hybrid structure can be implemented for broadband electro-optically controllable beam steering applications.
• Takashima, Y. (2017, Aug). 3D Visualization of Optical Ray Aberration and Its Broadcasting to Smartphones by Ray Aberration Generator. In IODC 2017.
• Takashima, Y. (2017, Aug). Cavity Enhanced Image Recording for Holographic Data Storage. In Proceedings Volume 10384, Optical Data Storage 2017: From New Materials to New Systems.
• Takashima, Y. (2017, Aug). Cavity enhanced eigenmode multiplexing with spatial light modulators for volume holographic data storage. In Proceedings Volume 10384, Optical Data Storage 2017: From New Materials to New Systems;1038407 (2017).
• Takashima, Y. (2017, Aug). Spherical Reflectors for Space Based Telescopes. In International Microwave Symposium 2017.
• Takashima, Y. (2017, May). Wide Field-of-View and Mid-Range Distance Imaging LIDAR by Digital Micro-Mirror Device. In CLEO 2017.
• Takashima, Y. (2017, Oct). Environmentally Robust Phase Detection Methods for Industrial Non-destructive Inspection. In Imaging Sensing and Optical Memory (ISOM) 2017.
• Takashima, Y. (2017, Oct). MEMS-based Single Chip Lidar. In FiO 2017.
• Takashima, Y., & Katayama, R. (2017). Optical Data Storage 2017: From New Materials to New Systems. In Optical Data Storage 2017: From New Materials to New Systems, 10384.
• Takashima, Y., & Miller, B. (2016, August). Cavity Enhanced Image Recording for Holographic Data Storage. In Optical Data Storage, in SPIE Optics and Photonics 2017.
• Takashima, Y., Chen, G., & Miller, B. (2016, August). Cavity enhanced eigenmode multiplexing with spatial light modulators for volume holographic data storage. In Optical Data Storage 2017, in SPIE Optics and Photonics 2017.
• Takashima, Y., Hellman, B., Smith, B., Gin, A., Chen, G., & Winkler, P. (2016, December). Wide Field-of-View and Mid-Range Distance Imaging LIDAR by Digital Micro-Mirror Device. In CLEO 2017.
• Tsai, D. P., Takashima, Y., & Katayama, R. (2017). Near-field coupling and readout of nano recording marks (Conference Presentation). In Optical Data Storage 2017: From New Materials to New Systems, 10384.
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  Near-field optical disk (NFOD) is a novel and demanded developments of optical storage technology. The nonlinear plasmonic coupling effect of the complete nano recording unit is important for increasing the near and far field optical readout contrast. Here, we present a simple plasmonic near-field coupling optical disk system. The near-field coupling effect between two nano-recording marks with various thickness of the dielectric spacer layer are investigated.
• Wu, P. C., Wu, H. J., Wang, H., Tsai, D. P., Takashima, Y., Katayama, R., Hsiao, H., & Chu, C. H. (2017). Ultra-thin film metasurface (Conference Presentation). In Optical Data Storage 2017: From New Materials to New Systems, 10384.
  More info

  Metasurfaces, the two-dimensional (2D) sub-wavelength artificial structures, where light is not required to have a deep penetration, have shown the ability to tailor the amplitude, phase and polarization of light. The functionalities of various optical components can be realized by metasurface-based design, such as beam splitters, filters, waveplates, deflector, lens and holograms. Here, we propose a new type of metasurface based on the concept of ultra-thin film interference and experimentally demonstrate its feasibilities in beam deflector, light focusing and broadband meta-hologram in visible spectrum. Considering an ultra-thin thin film interference system, a sandwich structure, composed of air, a lossy material layer and a metallic mirror, the reflection of this system can be regarded as the linear superposition of the partial reflections from first interface and from the cavity after several roundtrips. First, we calculate the phases and reflections of various thicknesses of amorphous silicon (a-Si) on top of aluminum layer under normal illumination of an unpolarized light in the wavelength region from 400 to 850nm. 2 π phase coverage can be achieved by changing the film thickness of a-Si within 50 nanometers. We select two thicknesses (2-level phase modulation) for the demonstration of meta-devices. The ultra-flat grating metasurface for beam steering are designed. The reflection angles of grating metasurface can be modulated by changing its period, while the specular reflection is inhibited. We further demonstrate computer-generated holograms (CGH) based on ultra-thin interference metasurface. The holographic images are reconstructed by the combinations of phase- and amplitude- modulation. These devices show the great potential and CMOS-compatibility in the application of optics, display, security printing, and metasurface-based optical storage system.
• Takashima, Y., & Miller, B. (2016, August). Cavity Enhanced Image Recording for Holographic Data Storage. In SPIE Optics and Photonics 2016.
• Takashima, Y., Hellman, B., Bosset, E., Ender, L., Jafari, N., McCann, P., Nguyen, C., Summitt, C., & Wang, S. (2016, December). 3D Visualization of Optical Ray Aberration and Its Broadcasting to Smartphones by Ray Aberration Generator. In International OSA Network of Students (IONS 2016).
• Takashima, Y., Hellman, B., Erstad, A., Kim, Y., Kim, J., & Min, S. (2016, August). Images Transfer through Thin Image Guides by Pseudo Phase Conjugation. In OSA Imaging and Applied Optics 2016.
• Takashima, Y., Hellman, B., Erstad, A., Kim, Y., Kim, J., & Min, S. W. (2016). Images transfer through thin image guides by pseudo phase Conjugation. In SPIE.
• Takashima, Y., Hellman, B., Erstad, A., Kim, Y., Kim, J., & Minc, S. W. (2016). Images transfer through thin image guides by pseudo phase conjugation. In SPIE.
• Takashima, Y., & Miller, B. (2015, Oct). Enhancement of Data Rates by Single and Double Cavity Holographic Recording” SPIE Optics and Photonics, Optical Data Storage. In SPIE Optics and Photonics, Optical Data Storage (ODS 2015).
• Takashima, Y., Espinoza, A., Gao, W., Cvijetic, M., & Odom, G. (2015, Aug). Optical design of communication simulator for orbital angular momentum based free-space link with an adaptive optics receiver. In SPIE Optics and Photonics, Laser Communication and Propagation through the Atmosphere and Oceans IV.
• Takashima, Y., Ge, T., Yang, J., Summitt, C., Wang, S., Johnson, L., Zaverton, M., & Milster, T. (2015, Feb). High contrast and metal-less alignment process for all polymer optical interconnect devices. In SPIE Photonics West, MOEMS-MEMS, Advanced Fabrication Technologies for Micro/Nano Optics and Photonics VIII (2015).
• Takashima, Y., Ishii, T., Shimada, K., & Hoshizawa, T. (2015, Oct). Pre-Write Operation and Post Optical Compnsation for Robust Holographic Data Storage System. In Intrenational Symposium on Optical Memory (ISOM 2015).
• Takashima, Y., Kim, Y., Kim, J., Summitt, C., & Wang, S. (2015, Aug). Design of X-ray Differential Phase Contrast Imaging System for High Energy and Incoherent X-ray Sources. In SPIE Optics and Photonics, Radiation Detectors: Systems and Applications XVI (2015).
• Takashima, Y., Shimada, K., Ishii, T., & Hoshizawa, T. (2015, Aug). Modeling and measures against the effect of mechanical instabilities on holographic data storage system. In SPIE Optics and Photonics, Optical Data Storage (ODS 2015).
• Takashima, Y., Summitt, C., Wang, S., Ge, T., Yang, J., Johnson, L., Zervarton, M., & Milster, T. (2015, Feb). Process Optimization for a 3D Optical Coupler and Waveguide Fabrication on a Single Substrate Using Buffercoat Material. In SPIE Photonics West, MOEMS-MEMS, Advanced Fabrication Technologies for Micro/Nano Optics and Photonics VIII (2015).
• Takashima, Y., Yang, J., Ge, T., Summitt, C., Wang, S., & Milster, T. (2015, Oct). All-polymer based fabrication process for an all-polymer flexible and parallel optical interconnect. In SPIE Optics and Photonics, Nanoengineering: Fabrication, Properties, Optics, and Devices XII (2015).
• Takashima, Y. (2014, Aug). Formalization and experimental evaluation of cavity-enhanced holographic readout. In Proc. SPIE 9201, Optical Data Storage 2014.
• Takashima, Y. (2014, July). Beyond 1 Mb/s free-space optical quantum key distribution. In 16-th. IEEE Conference of on Transparent Optical Networks.
• Takashima, Y. (2014, June). Design and Analysis of an X-ray Differential Phase Contrast Imaging System with Grating-less X-ray Source and Detectors. In IODC 2014.
• Takashima, Y. (2014, Mar). Alignment Process for Fabrication of Mirror-based Optical Via using Maskless Lithography Tool with Buffer Coat Materials. In IMAPS 10th International Conference and Exhibition on Device Packaging 2014.
• Takashima, Y. (2014, Mar). Micro-optics fabrication by mask-based and mask-less mixed lithography process towards 3D optical circuits. In Proc. SPIE 8974, Advanced Fabrication Technologies for Micro/Nano Optics and Photonics VII.
• Takashima, Y. (2014, May). Design of X-ray Differential Phase Contrast Imaging System for High Energy and Wide Spectrum X-ray Applications. In CLEO 2014.
• Takashima, Y. (2014, May). Evaluation of channel capacity of the OAM-based FSO links with a precise assessment of turbulence impact. In CLEO 2014.
• Takashima, Y. (2014, Oct). Beyond 1Mb/s Free-Space Optical Quantum Key Distribution via Orbital Angular Momentum and WDM-based MIMO in Turbulent Atmospheric Channels. In OFC 2014.
• Takashima, Y. (2014, Oct). Efficent Write Mode Control against Vibration Effect on Holographic Data Storage System. In ISOM 2014.
• Takashima, Y. (2014, Oct). Enhancement of channel capacity of OAM-based FSO link by correction of distorted wave-front under strong turbulence. In FIO 2014.
• Takashima, Y. (2014, Oct). New Optical Modeling of the Effect of Mechanical Instabilities on Holographic Data Storage System using Time Average Holography. In ISOM 2014.
• Takashima, Y. (2014, Oct). Phase contrast alignment for all polymer optical interconnect devices. In OSA-FIO 2014.
• Takashima, Y. (2014, Sep). Optical characterization of CMOS compatible micro optics fabricated by mask-based and mask-less hybrid lithography. In SPIE 9170, Nanoengineering: Fabrication, Properties, Optics, and Devices XI.
• Wang, S., Wang, S., Summitt, C., Ge, T., Johnson, L., Zaverton, M., Milster, T. D., Takashima, Y., Takashima, Y., & Wang, S. J. (2014). Alignment process for fabrication of mirror-based optical via using maskless lithography tool with buffer coat materials. In SPIE.
• Zaverton, M., Wang, S., Takashima, Y., Summitt, C., Milster, T. D., & Johnson, L. (2013). Flexible micro-optics fabrication by direct laser writing toward CMOS compatible 3D optical circuit. In Advanced Fabrication Technologies for Micro/Nano Optics and Photonics VI, 8613.
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  We demonstrated a 45 degree micro mirror by a direct laser writing method. A flat, smooth and clearly defined mirror surface has been fabricated despite of the finite size and long tail of the point spread function of the exposure tool.
• Takashima, Y., & Hesselink, L. (2011). Design and implementation of zoom objectives for multi-layer optical data storage. In Nonlinear Optics.
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  A zoom objective lens has been designed and implemented based on a newly proposed power arrangement having a constant focal length and a linear movement of single zooming component for selection of recording layers.
• Watkins, V. H., Takashima, Y., Shi, X., Pickett, J. E., Ostroverkhov, V. P., Natarajan, A., Misner, M. J., Mccloskey, P. J., Lorraine, P. W., Kim, E. M., Dylov, D. V., Chan, K. P., & Boden, E. P. (2011). Recent Progress in Micro-Holographic Storage. In Nonlinear Optics.
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  Advances in micro-holographic materials and systems are presented. New materials show improved index change (10x) and sensitivity (100x) at >3x lower intensity vs. previously reported. Experimental results supporting single-sided optical drive concept is presented.
• Takashima, Y., & Hesselink, L. (2007). En-squared power-based optical design for page-based holographic storage systems. In International Optical Design Conference 2006, 6342.
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  The Fourier transform lens consisting of an aspherical element is analyzed in terms of the supportable number of pixels by formalizing an en-squared-power ratio as a function of the Nyquist aperture ratio and aberrations.
• Takashima, Y., Orlov, S. S., & Hesselink, L. (2007). Lens designs for page-based holographic storage systems. In Optical Data Storage 2007, 6620.
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  An aspherical-meniscus and air-spaced-spherics are identified as minimum aberration configurations for page-based holographic recordings. Air-spaced-apsherics attain imaging NA’s of 0.7 for holographic recording only, and of 0.45 for a combination of holographic and surface recording.
• Takashima, Y., & Hesselink, L. (2006). En-Squared Power Based Optical Design for Holographic Storage Systems. In International Optical Design.
  More info

  The Fourier transform lens consisting of an aspherical element is analyzed in terms of the supportable number of pixels by formalizing an en-squared-power ratio as a function of the Nyquist aperture ratio and aberrations.

Presentations

• Takashima, Y. (2023).

  Optical Design Challenge Pitch - Nero

  . SPIE AR/VR/MR (2023).
• Takashima, Y. (2023). Image steering: delivering photons when and where they are needed.. Meta Reality Labs Research 5th AR/VR/MR Optics Academic Forum on October 11th, Redmond WA 2023.
• Takashima, Y. (2023). Multiplexed image-transfer and dynamic image-steering for Augmented Reality applications with Texas Instruments Digital Micromirror Device. AR, VR, and MR Vision Systems: Innovations, Promising Start-Ups, Future Roadmap, TechBlick, July 21.
• Takashima, Y. (2023). Optical Design Challenge Pitch - Pei. SPIE AR/VR/MR.
• Takashima, Y. (2023). Optical Design Challenge Pitch - Zhang. SPIE AR/VR/MR (2023).
• Takashima, Y. (2023). Solid-state and adaptive beam steering by Texas Instruments MEMS SLMs for Lidar and AR display. TxACE/SRC e-Seminar.
• Takashima, Y. (2023). Solid-state and adaptive laser beam steering by large area MEMS SLMs with high Technology Readyness Level. 5th LiDAR Tech forum, EAC 2023, June 6-7 (2023).
• Takashima, Y. (2020, June 2020). Lidar and AR Displays by MEMS-based Angular and Spatial Light Modulation. 12th International Conference on Optics-photonics Design and Fabrication (ODF 2020).
  More info

  Meeting postponed to June, 2021 due to COVID19 travel restriction.
• Takashima, Y. (2020, June 2020). MEMS Imaging Lidar. ICO-OWLS-2020.
• Takashima, Y. (2022). Beam- and Image-Steering for Lidar and Augmented Reality Applications with MEMS Spatial Light Modulators. Photonics Spectra Conferences.
• Takashima, Y. (2022). Optical Engineering: A Key Enabler for Technology in Daily Life. Optical Science Windter School.
• Takashima, Y. (2022). TI PLM to Advanced Lidar and Display Systems. Analog/Mixed-Signal, Circuits, Systems and Devices Annual Review, UT Dallas.
• Takashima, Y. (2022). Unlocking the potential of Digital Micromirror Device for AR display systems. Meta (Facebook) Reality Labs.
• Takashima, Y. (2021). A pathway towards advanced lidar and all-day AR display. Made it happen, Tech Launch Arizona.
• Takashima, Y. (2021). Diffraction efficiency of Texas Instruments Phase Light Modulator for quasi continuous laser beam steering. Annual TxACE Symposium.
• Takashima, Y. (2021). Infrared Light Modulation with MEMS Phase Light Modulator. Annual TxACE Symposium.
• Takashima, Y. (2021). Real time beam tracking by Texas Instruments Phase Light Modulator. Annual TxACE Symposium.
• Takashima, Y. (2020, Oct 2020). Phase, Wavelength, and Cavity Techniques for Holographic Data Storage Systems. Optoelectronic and Microelectronic Technology and Application (OMTA2020).
• Takashima, Y. (2020, Sep 2020). Disruptive space telescope concepts, designs, and developments: OASIS and Nautilus. European Optical Society Annual Meeting 2020.
• Takashima, Y. (2020, Sep. 2020). Emerging Technologies for Optics in Future: from AR Displays to Lidar”, Specially invited paper and panel discussion. The 56th Annual Meeting of the Japanese Society of Ophthalmological Optics (Focus 2020). https://www.56jsoo.com/program.
  More info

  Specially invited paper and panel discussion https://www.56jsoo.com/program
• Takashima, Y. (2020, Sep. 2020). Phase, Wavelength, and Cavity Techniques for Holographic Data Storage Systems. Invited for Optoelectronic and Microelectronic Technology and Application (OMTA2020).
• Takashima, Y., & Salem, M. (2018, August). Design of Phased Array Beam Steering Device for Situation Awareness Applications. SPIE Optics and Photonics.
• Takashima, Y., Cameron, P., Hellman, B., & Rodriguez, J. (2018, October). MEMS Based Beam Steering for Holographic LIDAR Systems. Council on Undergraduate Research, Research Experiences for Undergraduates Symposium.
• Takashima, Y., Hellman, B., & Rodriguez, J. (2018, May). Single-chip LIDAR. CLEO.
• Takashima, Y. (2017, Jun). Imaging Lidar. OSA Imaging Congress 2017.
• Takashima, Y. (2017, Oct). Interactive Graphical User Interface for Ray Aberration Generator 3.0. Research Experience for Undergraduates Symposium.
• Takashima, Y. (2015, Aug). Recent progress towards practical holographic digital data storage system. SPIE Optics and Photonics, Optical Data Storage (ODS 2015).
• Takashima, Y., Hesselink, H., Cheng, Y., Yuen, M., Orlov, S., Akameier, D., Aitkenhead, W., Kim, Y., Summitt, C., Wang, S., Herring, G., Chang, C., Pianetta, P., & Pease, F. (2015, June). Novel 3D X-ray Differential Phase Contrast Imaging System. Korea KBSI Seminar.
• Takashima, Y., Hesselink, L., Cheng, Y., Yuen, M., Orlov, S., Akameier, D., Aitkenhead, W., Kim, Y., Summitt, C., Wang, S., Herring, G., Chang, C., Pianetta, P., & Pease, F. (2015, June). Novel 3D Differential Phase Contrast Imaging System. Collaborative Conference on 3D and Materials Research (CC3DMR) 2105.
• Takashima, Y., Kim, Y., Summitt, C., & Wang, S. (2015, Aug). Design of Photonic-channeled X-ray Detector Array for Single Grating X-ray Differential Phase Contrast Imaging System. SPIE Optics and Photonics, Radiation Detectors: Systems and Applications XVI (2015).
• Takashima, Y., Kim, Y., Summitt, C., & Wang, S. (2015, Sep). Design and Optimization of Single Grating X-ray Differential Phase Contrast Imaging System with Free-form and Micro-optics-channeled Detector Array. SPIE Optical Design and Engineering V.
• Takashima, Y., Kim, Y., Summitt, C., & Wang, S. (2015, Sep). Fast and End-to-end X-ray Differential Phase Contrast Imaging Simulator. Optical Design and Engineering V.
• Takashima, Y., Kim, Y., Wang, S., Summitt, C., Yuen, M., Qi, C., & Hesselink, L. (2015, Aug). Virtual X-ray Differential Phase Contrast Imaging System Simulator. SPIE Optics and Photonics, Advances in X-Ray/EUV Optics and Components X (2015).
• Takashima, Y. (2014, Sep). Optical Compensation and Enhancement Techniques for Holographic Digital Data Storage System. SPIE Optics and Photonics, Optical Data Storage 2014.

Poster Presentations

• Takashima, Y. (2021). Diffraction efficiency of Texas Instruments Phase Light Modulator for quasi continuous laser beam steering. TxACE Annual Review Meeting.
• Takashima, Y. (2021). Infrared Light Modulation with MEMS Phase Light Modulator. TxACE Annual Review Meeting.
• Takashima, Y. (2021). Real time beam tracking by Texas Instruments Phase Light Modulator. TxACE Annual Review Meeting.