望远镜主镜柔性侧支撑机构设计研究

Research on Flexure Lateral Support Mechanism Design Applied to Primary Mirror of Telescope

侧支撑是大型望远镜主镜支撑的关键技术之一,侧支撑机构具有结构复杂、精密性高、运动量微小、无污染等特点,其性能优劣直接影响望远镜的成像质量甚至主镜自身安全。相比于传统机械式铰链机构,柔性结构具有体积小、无摩擦、无间隙以及无需润滑等优点,更加适用于大型望远镜主镜侧支撑机构。本文通过对柔性结构柔度矩阵的分析,利用等效弹性模量方法降低柔性结构设计及分析难度;针对一种基于运动学平衡原理的柔性侧支撑方式,通过等效弹性模量方法优化柔性结构尺寸,以满足大型望远镜主镜对于侧支撑机构的面形精度、定位精度、热匹配能力、固有频率的技术要求。

Lateral support is one of the key technologies of large telescope. Intricate structure, high precision, tiny stroke, and pollution-free are the most important characteristics of lateral support mechanism, which determine imaging quality and security of primary mirror. Compared with traditional mechanical pivot mechanism, there are advantages for flexure mechanism, which are smaller volume, friction-free, drawback-free, and lubrication-free. Due to these advan- tages, flexure mechanism is applied to lateral support system of large telescope primary mirror. In this paper, flexibility matrix of flexure lateral support mechanism was deduced, analyzed, and simplified. The size of flexure mechanism is depended upon equivalent Young＇s modulus method. Based on kinematic theory, a flexure lateral support mechanism has been designed. The flexure mechanism size is optimized to content the specification, which are the root-mean-square （RMS） of the mirror distortion accuracy, positioning accuracy, thermal adaptability, and natural frequency.