21 May 2014 A 250 frames-per-second 640 by 480 pixel division-of-focal-plane polarimeter for the visible spectrum
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The most common method of polarimetery involves imaging a scene through a polarization analyzer at multiple configurations. Switching among these configurations requires capturing multiple images of the scene, limiting the ability to capture real-time polarization data due to multiple scene sampling and motion artifacts. Advances in nanofabrication technology have allowed direct integration of polarization analyzers onto the sensor, enabling the capture of multiple analyzer intensities from a single frame. Using this technique, we have fabricated a high frame rate, VGA resolution, division of focal plane polarization imager for the visible spectrum. The imaging sensor is realized by monolithic integration of aluminum nanowires with an array of CCD imaging elements. The pixelated nanowire polarization filters are at four different orientations offset by 45° This allows for recording of the first three Stokes parameters at every super pixel, and subsequently the degree of linear polarization and angle of polarization are computed at 250 frames per second at full VGA resolution and over 1000 when limited to a subsection of the array. The imaging sensor also employs a per pixel calibration scheme which mitigates the variations in the aluminum nanowire sizes. We present an optical characterization of the sensor, and then utilize the increased frame rate to capture high speed polarization images of pieces of polycarbonate plastic placed under stress. The high frame rate allows us to recover strain information that regular rate sensors cannot.
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Timothy York, Timothy York, Radoslav Marinov, Radoslav Marinov, Viktor Gruev, Viktor Gruev, "A 250 frames-per-second 640 by 480 pixel division-of-focal-plane polarimeter for the visible spectrum", Proc. SPIE 9099, Polarization: Measurement, Analysis, and Remote Sensing XI, 909915 (21 May 2014); doi: 10.1117/12.2049832; https://doi.org/10.1117/12.2049832

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