由于红外镜片材料的温度特性, 环境温度的变化会对红外镜头的成像质量造成影响。为了研究不同温度场下镜片的应力状态以及镜面面形变化情况, 利用光机热集成分析方法, 运用有限元分析软件ANSYS WORKBENCH对设计的红外镜头进行了热结构耦合分析, 从分析结果中得到了镜片等效压应力的大小。利用Zernike多项式拟合了变形后的镜面面形, 将得到的Zernike系数导入到ZEMAX中建立了多重温度结构, 分析了不同温度下镜面变形前与变形后的光学系统离焦量的变化量。结果表明, 镜片在低温-40℃时受到较大的等效压应力, 最大等效应力81.118MPa, 小于材料的断裂强度345MPa; 不同温度下由于镜片面形发生变化, 导致红外光学系统成像质量以及离焦量发生改变。

Because of the temperature characteristics of infrared lens material, the imaging quality of infrared lens is affected when the environment temperature change. In order to study the stress state and the change of mirror surface shape of lenses at different temperatures, the method of thermal-structural optical integrated analysis is used. The thermal-structure coupling analysis for designed infrared lens was completed by ANSYS WORKBENCH, and the value of equivalent compressive stress of lens was obtained from the analysis results. Zernike polynomial was used to fit the deformed mirror surface, the Zernike coefficient was imported into the ZEMAX and the multiple temperature structure was established, then the variation of the defocusing amount of the optical system before and after the mirror surface deformation was analyzed. The results indicate that the lens is subjected to a equivalent compressive stress as 81.118 MPa at -40℃, which the value is less than the rupture strength 345MPa of lens material. The image quality and the defocus amount of the infrared optical system are changed at different temperatures due to the change of the lens surface shape.