针对1.2 m大口径望远镜主镜支撑系统, 为保证主镜面形精度均方根要求, 提出了一种有效的装调方法。该主镜支撑系统结合运动学原理, 分别设计了Whiffletree轴向支撑和柔性切向杆侧向支撑结构, 以保证其在较大温差范围内(-20~60 ℃)以及不同俯仰状态下(垂直-水平)始终具有较好的面形精度。机械加工误差及安装误差使柔性机构在组装过程中极易引入装配应力, 明显地增大主镜表面变形。借助于有限元软件对装调过程中可能出现的误差进行仿真分析, 根据结果制定装调流程, 并对实际装调进行指导。完成主镜支撑系统装调后, 采用补偿器和干涉仪对主镜的垂直检测及水平检测, 检测出两种状态下主镜的实际面形误差分别为λ/42和λ/31(λ=632.8 nm)。

According to 1.2 m large aperture telescope primary mirror support system, an effective assembly method was advanced to insure the root-mean-square (RMS) of the surface accuracy. The primary mirror support system was designed following kinematic principle. To achieve excellent performance of the RMS of primary mirror surface accuracy at different ambient temperature (from -20 ℃ to 60 ℃) and different elevation(from vertical to horizontal), whiffletree structure were used for axial support,while lateral support mechanisms based on flexible tangent link structure were adopted. Resulting from machining error and installation error of the flexible structures, assembly stress was presented certainly, that could increase primary mirror distortion range evidently. By the finite element analysis(FEA) simulation, the effects of various errors were calculated. According to simulation results, assembly processes were established. After assembly of primary mirror support system, the RMS of primary mirror surface accuracy was measured by compensator and laser interferometer. In measurement, the RMS of surface accuracy was λ/42 and λ/31(λ=632.8 nm), when optical axis of primary mirror was vertical and horizontal.