针对中型反射镜提出了一种柔性半运动学支撑方式, 以便简化主镜的支撑结构, 降低安装应力对主镜的影响, 以及提高主镜支撑对温度变化的适应性。对比小口径主镜的刚性半运动学支撑, 详细阐述了柔性半运动学支撑的特点和优势。运用该原理对一口径为710 mm的主反射镜的支撑进行了设计、分析、和检测, 其中反射镜的轴向采用6点带有柔性细杆的Whiffletree支撑, 径向采用带有柔性环的中心轴支撑。然后, 利用有限元方法进行了详细的结构优化设计。最后, 利用4D干涉仪对主镜竖直和水平两个工况进行了检测。检测结果显示: 反射镜的支撑面形与加工面形误差分别为8.7 nm和8.4 nm, 与有限元分析结果基本吻合, 验证了文中有限元建模和分析方法的合理性。提出的柔性半运动学支撑很好地保证了主镜面形精度, 综合性能良好, 达到了设计预期, 为中型主镜的支撑设计提供了重要的参考。

A flexible semi-kinematic support was proposed for a middle-sized mirror to simplify the support structure of the primary mirror , reduce its assembled difficulty and improve its adaptability to temperature variation. By compared with rigid semi-kinematic support for a small-sized mirror, the features and merits of the flexible semi-kinematic support were expatiated. Based on these features and merits, a support structure for the primary mirror with an aperture of 710 mm was designed, analyzed and tested, in which the axial support was Whiffletree with 6 flexible bars and the radial support was a center shaft with a flexible ring. Then, the finite element analysis was used to optimize the designed support structure. Finally, the mirror surface was tested by a 4D interferometer in vertical and horizontal states. The results show that the error between tested and machined is 8.7 nm and 8.4 nm, respectively, very proximity to the results of finite element analysis, which verifies the rationality of proposed modeling and analysis methods. In conclusion, the flexible semi-kinematic support maintains high surface figure accuracy and excellent combination property,so it provides an important value for middling mirror support.