Fiber faceplates to mitigate diffraction effects in an imaging snapshot polarimeter

Abstract

We investigate the advantages of employing a fiber faceplate in a snapshot polarimetry system. Our previous work at Sandia National Laboratories indicates that diffraction and propagation between the micropolarizer array, the microwaveplate array, and the Focal Plane Array (FPA) degrade performance, as quantified by the extinction ratio 1,2 . Crosstalk between adjacent pixels due to diffraction increases uncertainty of the measured polarization states in a scene of interest. These issues are exacerbated in the long-wavelength regime and as FPA pixel dimensions decrease. One solution, since it minimizes propagation distance, is to construct the micropolarizer and micro-waveplate arrays on a single substrate surface and to place this combination on the FPA 3 . This solution is a significant fabrication challenge and decreases yield due to its serial assembly nature. An alternative solution that would improve yield is to fabricate the micropolarizer on top of a fiber faceplate, place the faceplate on the FPA with the micropolarizer facing away, then place the waveplate array on top of the micropolarizer. The optical field that passes through the plane of the microwaveplate array and the micropolarizer array is guided to the FPA plane, without suffering diffraction effects associated with free-space propagation. We will quantify the utility of these proposed configurations with predicted imaging polarimetric system extinction ratios.