Electronic Military & Defense Annual Resource

5th Edition

Electronic Military & Defense magazine was developed for engineers, program managers, project managers, and those involved in the design and development of electronic and electro-optic systems for military, defense, and aerospace applications.

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increases instrument complexity, but gives us more freedom in the design space. We also evaluated a spatio-temporally modulated design (STD) that used only two rotating retard- ers (reducing instrument complexity over the four-retarder design), but using two retarders does not allow for as much improvement in temporal bandwidth. We can achieve a frame rate of one-eighth the base camera frame rate while reducing our spatial resolution by a factor of one-fourth with our quad retarder spatio-temporally modulated system. A typical (historical) dual-rotating retarder (DRR) Mueller matrix imaging system is limited to one-twenty-fourth the base camera rate, and there is no opportunity to trade off spatial resolution for temporal bandwidth. The following table outlines the performance improvements/tradeoffs of the spatio-temporal designs over the historical design. Our final design has a 300 percent temporal bandwidth improvement over the typical DRR system design. It is por- table and fast enough for research testing and remote sensing testing tasks. All of our components except for the camera can support faster acquisition so in the future we plan to upgrade to a higher speed camera (120 fps or more) to improve the effective Mueller matrix frame rate. In the next year, we intend to complete the control system software and begin field testing. The Future Of Polarimetric Imaging For TTI With the advent of linear systems theory for polarimetric sys- tems design — including partial Mueller matrix polarimeters (pMMP), which only measure some subset of the Mueller matrix — and advances in imaging science and machine learning for classification tasks, I believe we are at the incep- tion of inexpensive, reasonably fast, portable Mueller matrix polarimeters that will be adequate for TTI applications. Over the next five to 10 years, I fully expect polarimetric imag- ers to mature to (and perhaps surpass) the current level of hyperspectral imagers. Current research suggests that the fusion of passive polar- imeters and multispectral is coming very soon xi , but hybrid hyperspectral/active polarimetric instruments probably are more than five years away. It is a very exciting time for polari- metric imaging, and the pace of innovation is increasing in the field, especially for TTI and related applications, such as aerosol quantification and pollutant detection. References i I.J. Vaughn, "Stokes parameters review II," http://maxwellsmuse.com/stokes-parameters- review-ii/ ii Brian G. Hoover and J. Scott Tyo, "Polarization components analysis for invariant discrimina- tion," Appl. Opt. 46, 8364-8373 (2007) iii I.J. Vaughn, B.G. Hoover, J.S. Tyo, "Classification using active polarimetry," Proceedings of SPIE Vol. 8364, 83640S (2012) iv T. Wakayama, K. Komaki, Y. Otani, and T. Yoshizawa, "Achromatic axially symmetric wave plate," Opt. Express 20, 29260-29265 (2012) v M.W. Kudenov, M.J. Escuti, N.Hagen, E.L. Dereniak, and K. Oka, "Snapshot imaging Mueller matrix polarimeter using polarization gratings," Opt. Lett. 37, 1367-1369 (2012) vi C.F. LaCasse, T. Ririe, R.A. Chipman, J.S.Tyo, "Spatio-temporal modulated polarimetry," Proc. SPIE 8160, Polarization Science and Remote Sensing V, 81600K (September 9, 2011); doi:10.1117/12.896068. vii Andrey S. Alenin and J. Scott Tyo, "Generalized channeled polarimetry," J. Opt. Soc. Am. A 31, 1013-1022 (2014) viii D.A. LeMaster, K. Hirakawa, "Improved microgrid arrangement for integrated imaging polarimeters." Optics Letters 39(7), (2014) ix D. A. LeMaster, "Stokes image reconstruction for two-color microgrid polarization imaging systems," Opt. Express 19, 14604-14616 (2011) x regions with an active polarimetric imager," Opt. Express 19, 25367-25378 (2011) xi Andrey S. Alenin, Lynne Morrison, Clara Curiel, et al., "Hyperspectral measurement of the scattering of polarized light by skin," Proceedings of SPIE Vol. 8160, 816014 (2011) Technology 12 Figure 7: HyDMIP-P design schematic; LA denotes the illuminating laser, LP the linear polarizer, LR the linear retarder, MG the microgrid (micropolarizer) array and focal plane. The red rectangle represents a generic target. Electronic Military & Defense Annual Resource, 5th Edition Israel Vaughn is the principal engineer at maxwell's muse, llc, and a Ph.D. candidate in the Advanced Sensing Lab at the College of Optical Sciences, University of Arizona, studying under Prof. J. Scott Tyo. Vaughn has an extensive background in mathematics, instrumentation control, software engineering, and polarimetric imaging systems, and worked in industry for many years before pursuing a Ph.D. in optical engineering. Fig. 8: Channel structure in the Fourier domain of a channel structure, similar to the one used in our HyDMIP-P instrument. This design was accomplished using the linear systems theory developed for polarimetric systems. System Type Mueller matrix frames per second for a base camera @ 30fps Spatial resolution as a fraction of sensor resolution Typical DRR 1.25fps 1 (full sensor resolution) Dual retarder STD 1.875fps 1/4 Quad retarder STD 3.75fps 1/4

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