中文摘要：

为探索大口径超轻高精度可展开光学系统的可行性，对5m全口径空间可展开主镜的2m离轴分块镜进行了研究。首先通过分析和比较，确定了分块镜的材料、轻量化结构型式和支撑点的位置；然后，通过有限元建模和分析，得到面密度小于40kg／m2的超轻量化分块镜初始结构；最后，在分块镜3D板壳模型的基础上建立了带三个定位孔的3D实体模型。分析结果显示，分块镜在支撑条件下自重变形误差为7．93nmRMS／46．9nmPV，优于面形精度入／50RMS的要求，实现了超轻量化和高精度，且分块镜能承受发射状态下的力学环境。该研究为大口径超轻高精度可展开光学系统的工程应用提供了一种技术方案，具有工程实用价值。

英文摘要：

In order to explore the feasibility of large ultra-lightweight and high precision deployable optical systems, a 2 m SiC segmented mirror of a 5 m primary mirror was investigated. According to analysis and comparison, the mirror＇s material, ultra-lightweight structure pattern and support location were determined respectively. By FEM, an ultra-lightweight structure with areal density less than 40 kg/m2 was gotten. Based on 3D plate-shell model, a 3D solid model with three locating holes was built. The results show that the mirror＇s self-weight deformation is 7.93 nm RMS/46.9 nm PV under supports, and the ultra-lightweight mirror has enough strength to bear the stress at launch. The result meets the requirement in which the surface error should be less than A/50 RMS. The study may provide a technical scheme to develop the large ultra-lightweight deployable optical system.