Polarization diversity active imaging

Abstract

We present the concept of a Polarization Diversity Active Imager operating at (lambda) equals 810 nm. Each pixel of the image is encoded by the polarization degree Pd (0% < Pd < 100%) given by its Mueller Matrix. The measurement of the Mueller matrices is obtained using the Dual Rotation Retarder Technique. A theoretical analysis and an experimental validation of this technique are presented. The device is operating in a monostatic configuration, using a semiconductor laser ((lambda) equals 810 nm) to illuminate the target and a telescope to create the image on a CCD matrix. The experiment is controlled by a computer that drives the rotation of the retarders, the digitalization and the encoding of the image. The measured intensity and polarization images are compared and the information contained in the polarization degree are analyzed. Dual images (intensity-polarization) of different targets are presented, showing the experimental validation of the technique. The application of this active imager to the detection and the decamouflage of target buried in the background (same albedo but different polarization degree) is proposed.