航空变焦距镜头被动消热设计

Passive Athermal Design of Aerial Zoom Lenses

为减小温度对航空变焦距镜头成像质量的影响,设计了一种基于差动原理的被动消热结构。通过NXNastran有限元分析软件对变焦镜头在高温和低温两种工况下进行了热分析,利用消热原理及分析数据对变焦镜头4个组件进行了消热设计。对消热设计前、后的变焦镜头进行了消热结构耦合分析,分析结果表明变焦镜头经过消热设计后最大热变形量减小了0.03mm。利用泽尼克系数作为数据接口,将获得的热结构分析结果作为光学分析软件Code V输入,仿真出了消热设计前、后变焦镜头在+55℃时的光学传递函数曲线。和镜头设计传递函数值相比,消热设计前镜头在78lp/mm处传递函数值减小约0.2,传递函数值下降了50%,而消热设计后镜头传递函数值基本保持不变。仿真结果证实了消热设计的有效性。最后通过实验验证了仿真结果的正确性。

In order to diminish the negative temperature effect on image quality of aerial zoom lens, a passive athermal subtraction structure is designed, based on the differential principle. The thermal analysis of zoom lens in working conditions of both high and low temperatures is taken out through NX Nastran finite element analysis software, and the four components are designed by making use of athermal subtraction principle and analytical data. By means of the athermal structural coupling analysis on the zoom lens before and after design, it is proved that the reduction of the maximum athermal distortion of zoom lens is 0.03 mm on the lens after athermal subtraction design. By adopting the Zernike coefficient as the data interface and taking the obtained thermo-structural analysis results as the input of an optical analysis software named Code V, the optical transfer function curve of a zoom lens at ^-55 ~C before and after athermal subtraction design is simulated, Compared with the design value of transfer function of the lens, the transfer function value of the lens at 78 lp/mm before the athermal subtraction design is decreased by about 0.2, namely, the transfer function value is reduced by 50 %, while the transfer function value of the lens after the athermal subtraction design remains unchanged essentially. The effectiveness of the thermal subtraction design is verified. Finally, the correctness of the simulation result is verified through the experiment.