Design and simulation investigation of a large-aperture secondary mirror system with flexible passive support for...

The Multiplexed Survey Telescope (MUST) is a 6.5-meter class wide-field survey telescope set to be constructed in Lenghu Town, China. It features a concave hyperbolic primary mirror (M1) and a convex hyperbolic secondary mirror (M2). The M2 system is crucial for achieving the high image quality of MUST over a field of view (FOV) of 2.8° and must maintain precise surface accuracy under varying attitudes and environmental temperatures. To address the challenges associated with measuring and supporting large-aperture convex secondary mirrors, a novel secondary mirror system based on flexible passive support was proposed for MUST. This system enables the sub-aperture stitching measurement of the M2 during manufacturing under different attitudes and ensures stable performance across a wide temperature range of -40°C to +40°C, as well as operating attitudes from 0° to 90°. This paper presents the design, finite element modeling, and simulation results of the M2 system, exploring the effects of gravity, temperature variations, and assembly errors on M2 surface distortion and wavefront aberrations for the MUST telescope.