光学望远镜镜片旋转镀膜修正挡板的仿真设计

Simulation Design of Correction Masks for Optical Telescope Mirrors in Rotating Coating System

目的提高新疆天文台南山观测基地ZZS1800-1/G真空镀膜机的膜厚均匀性指标。方法通过建立旋转行星夹具系统的膜厚分布模型,利用高精度数值计算,基于ZZS1800-1/G真空镀膜机,研究镀膜机结构参数与镜面几何结构对膜厚均匀性的影响,分析蒸发源位置、望远镜镜片参数与修正挡板形状的关系,并进行修正挡板的仿真设计与验证。结果在旋转行星夹具系统中,蒸发源与原点的距离对半径较大的镜面膜厚均匀性的影响最为明显。该距离600 mm以内,在镜面半径小于100 mm时,膜厚均匀性均低于1.7%;镜面半径为600 mm时,膜厚均匀性最佳,为23%。加入修正挡板后,膜厚均匀性理论计算值为0.035%。在镀半径为600 mm的镜片时,为保证均匀性小于1%,修正挡板的加工形变量要控制在2.2%以内。结论加入修正挡板可有效提高ZZS1800-1/G真空镀膜机的膜厚均匀性,本文建立的仿真模型可为ZZS1800-1/G真空镀膜机在实际镀膜工作时修正挡板的设计提供理论参考依据。

This paper focuses on researching on the design method of correction masks utilizing for the mirror coating and aims to improve the film thickness uniformity based on ZZS1800-1/G vacuum coating machine,which equipped in Nanshan Station of Xinjiang Astronomical Observatory.By establishing the film thickness distribution model and using high precision numerical calculation,we studied the effects of structural parameters corresponding to ZZS1800-1/G vacuum coating machine and geometry structural parameters corresponding to different mirrors on film thickness uniformity,and analyzed the relevance between the shape of correction mask and the position of evaporate sources,parameters of the mirror,and display the simulation and numerical validation results of correction mask.Results showed that the distance between the evaporation source and the origin was the most obvious influence on the thickness uniformity of the mirror film with larger radius in the rotary planetary fixture system.When the distance was within 600 mm,and the mirror radius was less than 100 mm,and the uniformity of film thickness was less than 1.7%;when the mirror radius was 600 mm,the best uniformity of film thickness was 23%;and the theoretical value of the uniformity was 0.035%after adding correction mask,which shows the necessity of adding correction mask.The deformation of the correction mask needs to be within 2.2%for the purpose of keeping the uniformity less than 1%when the mirror radius was 600 mm.Correction mask can effectively improve the uniformity for ZZS1800-1/G vacuum coating machine,the simulation model proposed in this paper provides theoretical reference for the design of the masks.