拼接主镜是建设大型天文望远镜最有效的技术途径, 尤其是对10 m及更大口径的望远镜.本文从光学衍射理论出发, 以10 m左右口径望远镜为例, 推导出了拼接望远镜光学系统点扩展函数的解析表达式, 建立了数学仿真模型, 并对影响望远镜系统远场像质的因素进行了计算分析.理论分析和仿真结果表明: 拼接望远镜的点扩散函数是分块镜的位置干涉函数和分块镜的点扩散函数的乘积; 分块镜间的间距会引起分块镜的衍射光斑展宽, 使远场峰值能量下降; 分块镜的平移误差会严重影响望远镜点扩散函数中的位置干涉函数, 从而降低望远镜系统的斯特列尔比; 分块镜的倾斜误差会在每个分块镜的点扩散函数引入频移, 因而影响拼接望远镜光学系统的点扩散函数, 降低望远镜系统的斯特列尔比.

The Segmented Telescope is the most effective way to build a giant telescope. 10 meter and larger telescopes are needed to be carried out further for our country. The analytical expression of the Point Spread Function (PSF) for 10 meter Segmented telescope was derived, based on optical diffraction theory. A numerical simulation model was established. The Gaps of Sub-segmented mirrors and Piston error, which affect far-field image quality, were analyzed. Both theoretical analysis and simulation results demonstrated the following: PSF of Segmented telescope can be obtained by multiply coherence function(GF) of Sub-segmented mirrors′ center position with single Sub-segmented mirror′s PSF. Gaps between Sub-segmented mirrors could blur diffraction spot and decrease the peak energy. Piston error of the Sub-segmented mirror could affect the GF of the PSF seriously. Thereby, Strehl Ratio of the system could be decreased and the frequency of GF is not changed. Tip-Tilt error of Sub-segmented mirrors would cause frequency shift in every PSFs and the whole PSF could be affected and the Strehl Ratio would be decreased.