Gravity-Thermal Coupling Response of a 1m Off-Axis Primary Mirror for AIMS Telescope

Abstract

This paper takes the 1-meter off-axis primary mirror of the AIMS solar telescope as the research object, and adopts the finite element method to analyze its gravity-thermal coupling deformation characteristics under seven elevation angles and three temperature conditions. The results show that the worst surface figure of the primary mirror occurs at −15◦C and 0 ◦ elevation, with an RMS surface accuracy of λ/112.9 (@ 632.8 nm, corresponding to PV = λ/16.4). It is found that the mirror surface error exhibits a non-monotonic variation law with the elevation angle, which is mainly dominated by the temperature-dependent stiffness of the radial unloading mechanism and the direction of the gravity vector. An empirical model between the surface figure error (RMS), temperature and elevation angle is established in this study, which can provide quantitative support for the active optics correction and observation optimization of the telescope.