Fused spectropolarimetric visible near-IR imaging

We report on the development and characterization of a compact, lightweight, robust, and field-portable spectropolarimetric imaging system at the U.S. Army Research Laboratory (ARL). It operates in the 400 to 900 nm region with a passband of 10 nm at 600 nm. This automated imager is designed using a tellurium dioxide (TeO₂) acousto-optic tunable filter (AOTF) as an agile spectral selection element and a commercial nematic liquid-crystal variable retardation (LCVR) plate as a tunable polarization selection device with an off-the-shelf uncooled charge coupled device (CCD) camera and optics. Image acquisition with both spectral and polarization features facilitates significant improvement in target detection. This paper has described the design concept and a program, with a detailed description of the VNIR imager, and present images obtained from it and the analysis of the results.