Optimization of structural parameters of sparse apertures with four rectangular sub-apertures

A sparse aperture consisting of four rectangular sub-apertures for deployable mirror was presented. An R-C system is designed before analysis. The pupil function and the modulation transfer function (MTF) were calculated and analyzed. The strict expression of MTF of diffraction limited system with this aperture was given. In order to solve the problem that the minimum of MTF in partial directions are close to zero when the fill factor is high, the sub-aperture configuration is optimized based on the relationship curve between MTF minimum and sub-aperture’s length-width ratio. In this paper, the MTF evaluation indexes along with calculation methods for four rectangular sub-aperture sparse aperture structure are given, including MTF average and average MTF curve. Imaging simulation of the system shows that the resolution of the unoptimized structure is low in horizontal and vertical directions, while the image quality of the optimized structure is similarly high in all directions.