Study Of Phase Compensation Technique For Optical Sparse-Aperture Imaging System

Optical sparse aperture imaging system is composed of several subapertures that arranged according to specific rule, it images using interferometry, and its resolution is higher than any subaperture. Coherent phased beam combining is the key for sparse aperture system to achieve high resolution. Therefore the beam combining errors are the main reason which affect the resolution of sparse aperture system. This paper mainly undertake the study of phase compensation technique for beam combining errors.Analysis of three beam combining errors is done in the paper, they are Piston Error、 Tip/Tilt Error and Pupil Mapping Error, and they need to be kept within certain tolerance values to achieve coherent phased beam combining.Three error measurement methods are discussed for beam combining errors, they are Shack-Hartmann techniques、Pyramid techniques and Phase Diversity techniques, then beam combining errors can be measured precisely by using these methods independently or together. In the following, Optical Delay Line (ODL) is designed for control of beam combining errors, by means of coupled design of OPD and FSM, precisely control of beam combining errors can be achieved to keep coherent phased beam combining, thus sparse aperture system can image with high resolution.