透镜面形精度是影响透射式光学系统性能的主要因素之一, 支撑结构、自重和热载荷是引起透镜面形发生变化的三个主要原因。为了实现大口径透镜 (Φ>200 mm)的高面形精度, 本文设计了一种新的基于多点柔性支撑的透镜支撑结构, 通过有限元分析, 给出该柔性支撑结构下自重和热载荷对透镜面形的影响。分析结果表明: 重力作用下透镜上、下表面面形 RMS值分别为 6.78 nm和 3.46 nm; 热载荷作用下透镜上、下表面面形 RMS值分别为 8.30 nm和 5.57 nm。由此得出, 本文设计的多点柔性支撑结构可以有效减少自重和热载荷对大口径镜面面形的影响, 满足透射式光学系统对透镜面形的精度要求 (RMS<λ/50, λ=632.8 nm)。

The surface-profile precision of lens is a main factor which influences the performance of the optical system.There are three main reasons which influence the lens surface-profile most, and they are the supporting structure, gravity and thermal load.In order to achieve the goal of getting high surface-profile precision of the lens (Φ>200 mm), a new multi-points flexible supporting structure is designed.Then, the influence of gravity and thermal load with the designed structure is analyzed.The results are as follows: for the deformation caused by gravity, the surface root-mean-square (RMS) value is 6.78 nm and 3.46 nm for the upper and lower surface respectively; for the deformation caused by thermal load, the surface (RMS) value is 8.30 nm and 5.57 nm for the upper and lower surface respectively.The designed structure with multi-point flexible support can effectively reduce the influence of precision loss which is caused by gravity and thermal load, and meet the requirements of high surface-profile precision of large-aperture lens for transmission-type optical system(RMS<λ/50, λ=632.8 nm).