A Spectro-Polarimetric Imager for Scene Discrimination

Abstract

We have assembled a wide spectral range, all-electronic spectro-polarimetric imager utilizing an acousto-optic tunable filter (AOTF), a liquid crystal variable retardation plate, and real-time, software-adaptable signature masks. This combination of rapidly adjustable parameters allows operation at 30/sec. frame rate, and near real time adaptability to changing target signatures. The spectral capability of the AOTF permits us to apply simultaneous, multiple wavelength filtering which greatly increases selectivity. Electronically agile polarization analysis adds a valuable signature feature for many scenarios. The adjustable retardation gives the capability to analyze and display not only linear polarization, but more generally, elliptical polarization as well. We have developed background suppression algorithms based on spectral and polarization signatures so that a wide variety of targets may be displayed with greatly enhanced contrast. We present several examples of battle scene target identification and detection of road hazards for vehicle navigation.