Lab and Field Measurements to Evaluate a Differential Polarimetric IR (DPIR) Search Sensor

Differential polarimetry has shown the ability to enhance target signatures by reducing background signatures, thus effectively increasing the signal-to-noise ratio on target. This method has mainly been done for resolved, high contrast targets. For ground-to-air search and tracking of small, slow, airborne targets, the target at range can be sub-pixel and hard to detect against the background sky. Given the unpolarized nature of the thermal emission of the background sky, it should be possible to use differential polarimetry to "filter out" the background, and thus enhance the ability of detecting sub-pixel targets. The first step in testing this hypothesis is to devise a set of surrogate sample targets and measure their polarimetric properties in the thermal IR in both the lab and the field. The goal of this paper is to determine whether or not it is feasible to use differential polarimetry to search, detect, and track small airborne objects.