2m SiC反射镜拱形轻量化结构设计

Lightweight Design for 2 m SiC Arch Mirror

针对口径为2060mm的地基大口径望远镜主反射镜,选用SiC材料和新型拱形轻量化结构进行了详细的轻量化参数设计,并对支撑环半径进行了优化。对于Whiffletree18点支撑和27点支撑形式,从静力学(重力作用)和热力学两方面对比分析了两种轻量化结构的镜面变形,结合SiC反射镜的加工工艺,最终确定18点支撑的轻量化结构为首选方案。同时,就SiC反射镜对稳态温度差导致的热变形较敏感的问题,提出可通过设计与镜体热变形相匹配的支撑结构来满足镜面变形的要求。

For a primary mirror with the diameter 2 060 mm in large aperture based-ground telescope, parameters of new arch light-weighted structure are detailedly designed with the material SiC. Meanwhile, radius of supporting rings is also optimized. According to 18-point and 27-point Whiffle tree support scheme, mirror deformation for two models is analyzed and contrasted individually in statics （gravity effect） and thermodynamics. Considering the processing technic of SiC mirror, the 18-point supporting light-weighted structure is judged to be the preferred scheme at last. However, thermal deformation for SiC mirror is sensitive to the steady temperature difference. Referring to this problem, a measure that the supporting-structure design should be suited to the mirror thermal deformation is provided to achieve the design requirements.