Tolerance design of short focal length catadioptric telescope for remote sensing instruments with sub-meter resolution

A short focal length telescope is essential for remote sensing instruments (RSI) to achieve sub-meter resolution, with the premise of precise fabrication and alignment. The tolerance becomes tighter when the focal length becomes shorter, which makes the assembly issue even harder. In this paper, the catadioptric telescope with short focal length is taken as the target for developing a design methodology with the consideration on the permissible tolerance specifications of mirror surface root-mean-square (RMS) wavefront error (WFE) in system tolerance for fabrication, as well as the tolerance of surface tilt and decenter of mirror in assembly process. The parameter chosen as the trade-off variable is the aperture size of the telescope, and the tolerance budget for aligning high-resolution RSI is evaluated upon the requirement of a ground sampling distance (GSD) less than 60 cm. The result has been used as the guideline for finding optimal aperture size in an experimental remote sensing satellite (RSS) project.