低温红外镜头设计仿真方法及试验验证

Simulation method and its test verification of cryogenic infrared lens design

在低温环境下镜头结构会产生热变形,对镜头光学传递函数(MTF)及离焦量均会产生影响,从而影响光学成像质量。在此基于某红外遥感器,针对210 K低温工作环境,设计了一套具备热卸载功能的透射式低温镜头。对其建立有限元模型,并加载模拟在轨工作环境温度场,得到热变形数据,最终计算出镜头MTF及离焦量变化,并通过该仿真分析手段对低温镜头结构进行优化设计。低温镜头装调完成后,将低温镜头及其他配合测试设备置于真空罐内,在常温与低温环境条件下,对光学系统MTF及最佳焦面位置进行测试标定。测试结果表明,各项偏差在可接受范围之内,MTF仅变化0.2%,说明使用的低温镜头多场耦合仿真方法是可靠的,能够对红外遥感器低温镜头设计进行指导。

At low temperature,the lens structure will produce thermal deformation,which will affect the modulation transfer function(MTF)and defocus of the lens,thus affecting the quality of optical imaging.Based on an infrared remote sensor,a set of transmission cryogenic lens with thermal unloading function was designed for the 210 K low-temperature working environment.The finite element model was established,and the thermal deformation data was obtained by loading the simulation of the in-orbit working environment temperature field.Finally,the variation of lens MTF and defocusing amount were calculated,and the structure of cryogenic lens was optimized through this simulation analysis method.After the installation and adjustment of the cryogenic lens,the cryogenic lens and other test equipment were placed in a vacuum tank,and MTF and the best focal plane position of the lens were tested and calibrated under ambient temperature and low temperature conditions.The test results show that the errors are within the acceptable range,the MTF variation is only 0.2%,indicating that the cryogenic lens multi-field coupling simulation method is reliable and can guide the design of cryogenic lens for infrared remote sensor.