A Dual Wave Infrared Imaging Polarimeter

Detection of targets can be difficult using thermal camera during thermal cross-over periods. Under these conditions, the target takes on the apparent temperature of objects in the foreground or background and becomes undetectable. It is commonly said that the thermal imagery is "washed-out". When the thermal contrast of an object against its background is zero, many times a polarization contrast of the same object is non-zero. In this paper, we introduce a camera that measures thermal and polarization images in both the mid-wave infrared (MWIR) and long-wave infrared (LWIR). We also show example images and derive a simple equation that explains the conditions under which a polarization signature of an object can be expected.