Two optronic identification techniques: lidar-radar and multispectral polarimetric imaging

We propose to review two concepts that can be used for target detection and identification in optronic systems: lidar-radar and multipectral polarimetric active imaging. The lidar-radar concept uses an optically pre-amplified intensity modulated lidar, where the modulation frequency is in the microwave domain (1-10 GHz). Such a system permits to combine directivity of laser beams with mature radar processing. As an intensity modulated or dual-frequency laser beam is directed onto a target, the backscattered intensity is collected by an optical system, pass through an optical preamplifier, and is detected on a high speed photodiode in a direct detection scheme. A radar type processing permits then to extract range, speed and profile of the target for identification purposes. The association of spatially multimode amplifier and direct detection allows low sensitivity to atmospheric turbulence and large field of view. We present here the analysis of a lidar-radar that uses a radar waveform dedicated to range resolution. Preliminary experimental results are presented and discussed. For the multispectral polarization active imaging concept, the acquisition, at different wavelengths, of images coded in intensity and in degree of polarization enables to get information about the spectral signature of targets as well as their polarization properties. A theoretical analysis and a experimental validation of this technique are presented. Preliminary experiments, using a monostatic configuration, will be also presented.