拼接子镜力矩促动器布局的优化设计

Layout optimization of warping harness for segmented-mirror telescope

为了降低较为昂贵的镜面抛光和光机装配费用,以及应对温度、重力及其他意外因素导致的镜面低阶像差,一种在被动浮动支撑结构上施加力矩以实现面形实时校正的力矩促动器在部分望远镜上已有成熟应用。本文旨在针对我国未来的大口径地基光学望远镜,对其拼接子镜力矩促动器的分布进行优化与设计。根据工程经验和参考文献初步确定力矩促动器所需的校正能力,通过三维建模软件对拼接子镜及镜室进行建模,最后通过有限元仿真和最小二乘法拟合对力矩促动器的布局进行优化设计。计算结果表明,采用18个力矩促动器的分布方案能够对离焦、像散、彗差和三叶像差进行良好的校正。对于具有数百面子镜的拼接望远镜来说,18个力矩促动器方案在满足光学设计需求的同时,有效节约了建设经费并降低了工艺的复杂性。

To reduce the high costs of mirror polishing and opto-mechanical assembly,and to correct low-order aberrations caused by thermal and gravity deformation,the so called'warping harness'has been used to apply moment to the pivot of whiffletrees to achieve real-time correction of the mirror surface.Indeed,warping harnesses have been adopted in some large astronomical telescopes.This study aimed to optimize the layout of actuators that may be applied to large optical telescopes in China in the near future.Firstly,the correction ability of the warping harness was determined according to engineering experience and the wider literature.Secondly,integrated modeling of the segment support assembly was carried out using 3 Ddrawing software.Finally,the layout of actuators was optimized using finite element simulation and the least-squares method.The results show that an optimized design of 18 actuators can correct aberration of focus,astigmatism,coma,and trefoil.The design of18 actuators not only meets the requirements of optical design,but also has a lower cost and higher efficiency.