大口径主镜的侧向定位系统

Lateral positioning system for large aperture primary mirror

针对采用Whiffletree式底支撑和推拉平衡重式侧支撑的大口径主镜在主镜室中的准确定位,基于运动学约束原理提出了一种大口径主镜侧向定位方法。介绍了运动学约束的基本原理,提出了一套主镜侧向定位系统实现方案,包括定位点位置的选取、柔性铰链和定位基座的设计,并设计了一种侧向定位系统。利用有限元方法,分析了设计的侧向定位系统对大口径主镜系统的位置、谐振频率和镜面面形精度等方面的影响。结果表明,使用该侧向定位系统的整个主镜系统谐振频率达到13.6Hz,光轴水平时主镜沿Y轴方向的平均位移为-355.863nm,镜面面形未受影响,所有指标均满足设计要求。实验结果验证了提出的主镜侧向定位系统设计方案对大口径望远镜主镜的支撑和定位系统设计具有工程指导意义。

To locate accurately a large aperture primary mirror with balance weight support and Whiffletree support in the primary mirror cell,a lateral positioning method for the large aperture primary mirror was proposed based on the kinematic constraint.The principle of kinematic constraint was introduced,a design scheme of lateral positioning system for the primary mirror was proposed including the selection of location points and the design of flexure hinges and location bases,and then a lateral positioning system was implemented.With finite element method,the influences of the lateral positioning system on the large aperture primary mirror system was analyzed in several aspects,such as system location,resonant frequency and mirror surface profile.As the results,it shows that the resonant frequency of the primary mirror reaches 13.6 Hz,the average displacement of the primary mirror is-355.863 nm along the Y-axis direction,and the primary mirror surface profile is uninfluenced.These parameters all meet the design requirements of this lateral positioning system.Experimental results verify the engineering signification of proposed lateral positioning system on the design of support and position systems of primary mirror in large aperture telescopes in the future.