Design and analysis of support system of LAMOST primary mirror

LAMOST (The Large Sky Area Multi-object Fiber Spectroscopic Telescope) is a reflecting Schmidt telescope. There are two large segmented mirrors in LAMOST: One is the Schmidt plate M-A, and the other is the spherical primary mirror M-B. The dimension of M-B is about 6.7m x 6m and it is face down in 25degrees. M-B is composed of 37 hexagonal sub-mirrors. During the observation, one should maintain the correct mirror figure for each sub-mirror and co-focus for all 37 sub-mirrors to obtain the good image, even it is an unconventional designed telescope without tracking movement on the primary mirror. This paper presents the design and the finite element analysis for the whole primary mirror support system, which includes the optimization of the mirror support points distribution, the design and the testing of the prototype of M-B sub-cell, the structure analysis and the design of the mirror support truss.