为提高真空相机光学性能, 对现有改正镜作为真空相机封窗进行了可行性研究。通过现有改正镜几何模型, 将力学场映射到有限元模型中, 计算改正镜在受大气压强差状态下的变形。利用最小二乘法求解Zernike多项式前6项系数和拟合求解改正镜面形方程, 分析变形后的改正镜对真空相机像质影响。研究结果表明: 相对于原有像质的弥散半径, 变形后的改正镜使得真空相机点阵图的弥散半径增大且最大增大41.9%, 通过调节CCD焦距从249.554 mm变为249.574 mm, 使得CCD点阵图弥散半径相对于原来增大0.301%~1.09%, 保持了LAMOST低分辨率光谱仪相机原有的像质要求, 说明现有改正镜可直接用于真空相机设计方案。

To improve optical performance of vacuum camera as the goal, feasibility of existing corrector lens as a vacuum camera window is studied. Through existing geometric model of corrector lens, mechanics field is mapped into the finite element model, and deformation of corrector lens under atmospheric pressure difference is calculated. The least squares method is used to solve 6-order coefficients of Zernike polynomial and the fitting solution are used to solve corrector lens shape equation. Effect of modified corrector lens on vacuum camera image quality is analyzed. Results show that deformation radius of the latent image of vacuum camera is 41.9% higher than that of original image, but CCD focal length changes from 249.554 mm to 249.574mm, so that CCD diffuse radius of bitmap is between 0.301% and 1.09% of the original, and the original image quality of LAMOST low-resolution spectrometer camera is maintained. Therefore, existing corrector lens can be used directly in vacuum camera design.