Correction experiment of 620mm thin mirror active optics telescope

For 620 mm diameter active optics telescope, surface error correction for primary mirror and system wavefront aberration correction experiment were carried out respectively. The support system of primary mirror consisted of 36 axial active supports and 6 lateral passive supports, in which 33 axial supports were used for active correction, and 3 were used as dummy hard points for controlling the position of primary mirror. The Shack-Hartmann wavefront sensor was used as testing equipment and the least square method was used to calculate the active corrective forces. In the experiment, low frequency Zernike terms were selected for correction through analyzing the correction ability of the system. Through fixing the S-H sensor at the curvature center of primary, the mirror surface error correction experiment was carried out at different elevation, and around 0.6RMS surface error of the initial state can be corrected to /12-/15 RMS. Then the wavefront error of the telescope system was corrected using the star object of collimator, around 0.65RMS of the initial state was corrected to 0.2RMS, and the resolution is improved from 18 lp/mm to 45 lp/mm correspondingly.