The application of wavefront coding technology to a large segmented synthetic aperture telescope

Abstract

The utilization of a telescope with a large single aperture is limited by the manufacturing technique, cost, volume and weight of a monolithic mirror. In order to solve these problems, the technology of the segmented synthetic aperture was introduced. The primary mirror of a large segmented synthetic aperture telescope consists of several segmented mirrors, whose misalignment errors make the wavefront change drastically and influence the MTF of the optical system badly. The wavefront coding technology (WFC) is an innovative technology that joints the optical design and digital image processing together. By adding a phase mask close to the pupil of an optical system and modulating the wavefront, the WFC system becomes very insensitive to defocus and other aberrations based on defocus. The theoretical analysis of characteristics of the WFC system was done in the form of PSF. The application of WFC to a segmented three mirror anastigmat (TMA) was presented. A space telescope with an effective focal length as 40m, a F number as 10, a field of view as 0.5°x0.05° was designed, whose primary mirror consisted of seven segmented mirrors. The influence of defocus and misalignment errors on the telescope was discussed. The imaging process of the WFC system and following image restoration were simulated. As a result, sharp images were obtained and the large segmented synthetic aperture telescope had looser misalignment tolerance and extended depth of focus.