Target recognition study using polarimetric laser radar

Imaging laser radar (ladar) systems have been developed for automatic target identification in surveillance systems. A processor in the ladar uses the range value at the target pixels to estimate the target's 3-D shape (angle-angle-range) and, from the 3-D shape, identify the target. For targets in clutter and partially hidden targets, there are ambiguities in determining which pixels are on target, that lead to uncertainties in determining the target's 3-D shape. A method for improving the determination of which pixels are on target is to use the polarization components of the reflected light. Laser light retroreflected from man-made (smoother) surfaces is depolarized less than light from natural (rougher) surfaces. By sensing the depolarization of the reflected light at every pixel, the pixels on target can be distinguished from pixels on clutter and background. We describe the operation of a polarization diverse imaging laser radar and a preliminary evaluation of this ladar. We simulated the laser radar output, which are polarization diverse images. The polarization diverse images are fused into a single image. We then showed that, using the fused image, we are better able to identify and distinguish the target from other objects of the same class.