Error analysis and compensation of a segmented flat diffractive telescope

Segmented flat optics has been considered promising for future spaceborne imaging systems with apertures exceeding 10 m. Nonetheless, subaperture errors considerably degrade the image quality. This study focuses on analyzing the impact of six types of misalignment errors and three types of fabrication errors that can cover most errors in such a stitching system. A proof-of-principle simulation with eight subapertures was performed, and the system's tolerance of misalignment and fabrication errors were subsequently determined. In particular, a 13-m segmented flat imaging system with 72 subapertures was designed to investigate the errors in a practical scenario. Moreover, an aft compensation optic is inserted to compensate for the subaperture errors. Simulation results show that our error analysis theory and compensation method are efficient and accurate, which could provide guidance for future large-scale aperture stitching.