大口径非球面透镜支撑方法的优化

Optimization on Supporting Method of Large-Aperture Aspheric Lens

大口径光学镜面检测系统常常需要透镜元件。透镜元件由自重引起的表面变形严重干扰了系统成像质量,优化设计合适的支撑方案获得较小的变形量是较为关键的工作。针对某检测装置中直径为1.5m的透镜进行研究,使用三维绘图软件Solidworks和有限元软件Ansys模拟透镜支撑点的位置和力的大小,通过实验设计软件Design-Expert以及Ansys中的OPT模块进行优化,选定最佳的设计方案,借助Zernike多项式拟合出透镜前后表面的面形。结果表明:透镜两个表面变形量的均方根(RMS)值分别为1.85nm和3.28nm,波峰-波谷值分别为9.4nm和24.4nm,透镜的整体变形量引起的透射波前像差RMS值为0.998nm,满足镜面检测对于透镜的精度要求。

Usually, a lens is used in a large-aperture mirror testing system. The deformation caused by gravity of the lens seriously influences imaging quality, so it is a critical work to reduce deformation of a support system by optimization. We investigated a large-aperture lens with 1.5 meter diameter in a testing system, and the 3D solid model constructed by Solidworks was imported into Ansys software for finite element analysis. The position of support points and support force were optimized with Design-Expert software and OPT workbench of Ansys. The front and rear surfaces of the distorted mirror were simulated with Zernike polynomial. The root mean square （RMS） values of the two surfaces deformation are 1.85 nm and 3.28 nm, Peak to valley （PV） values are 9.4 nm and 24.4 nm. Meanwhile the RMS wavefront error is 0. 998 nm, which meets the technical requirements.