Active compensation for optimal RMS wavefront error in perturbed off-axis optical telescopes using nodal aberration theory

Abstract

This paper presents an active compensation strategy for RMS wavefront error of perturbed off-axis telescopes in the framework of nodal aberration theory. First, the orthogonalized expression of the wave aberration function in the vector form for perturbed off-axis telescopes is derived by using RMS normalization. The orthogonalized aberration function is applied to analytically describe the RMS wavefront error in perturbed off-axis telescopes with circular apertures. Then, the system compensation model for perturbed off-axis telescopes is established. The compensation model takes the weighted square sum of the RMS wavefront errors at representative field points as the objective function, which is minimized to obtain the optimal compensation solution of off-axis systems with perturbation constraints. The compensation model is solved by using a particle swarm optimization algorithm. Then, the off-axis three-mirror anastigmatic telescope is taken as an example, and the system compensations for the misaligned tertiary mirror and deformed primary mirror are discussed. After compensation, the average RMS wavefront errors in the perturbed off-axis systems are greatly reduced, which can well meet the system requirements. Finally, Monte Carlo simulations of the optimal compensation method and sensitivity table method are carried out to demonstrate the correctness and accuracy of the proposed method.

An in-orbit correction method based on CNN for the figure errors and component misalignments of TMA telescope

“…When the TMA telescope works on orbit, due to its own errors of design, manufacturing and alignment and the influences of external environment such as temperature change and gravity effect, the image quality of the perturbed system will deteriorate caused by both the figure errors of the primary mirror (PM) and the misalignments of the secondary mirror (SM) and tertiary mirror (TM). To solve the problem, the optimal strategy is to compensate for system aberrations of the perturbed TMA telescope by adjusting the smaller mirror such as the SM [1][2][3] . Two kinds of traditional methods have been used to realize the system aberration compensation.…”