Analytic versus adaptive image formation using optical phased arrays

Current optical phased arrays produce images by adaptively phasing the output of several telescopes on a common focal plane. Image based phasing techniques such as Phase Diversity, are used to maintain the phasing in real time. This requires both a computationally intensive algorithm for estimating the phasing errors as well as a means for rapidly adjusting the optical path length through each telescope. In this paper we will compare the adaptive technique of phasing multiple telescopes with the analytic technique of digital holography. Digital holography provides a means of digitally estimating and correcting the phasing errors between the multiple telescopes. The process can occur long after the data has been acquired which relaxes the requirements on the stability of the phased array as well as the mechanical complexity. Experimental results will be shown for adaptive and analytical image formation in remote sensing applications.