Performance of differential synthetic aperture ladar versus phase-gradient autofocus at large phase errors and low return levels

The performance of differential synthetic aperture ladar (DSAL) processing versus phase-gradient autofocus (PGA) technique in SAL image formation is demonstrated experimentally using phase history data (PHD) with large random phase errors and various target returns generated from a laboratory DSAL setup operating at 1550-nm wavelength. Results show that at strong return levels, both DSAL and PGA are very robust in focusing high-resolution images from the PHD; whereas, as target returns become weak and PHD is dominated by noise, the iterative PGA performs less effectively than the DSAL does. It is concluded that, on the whole, the DSAL technique is possibly more robust than PGA in both effectiveness and efficiencies. (C) 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)