8～12μm红外动态热像模拟器光机结构设计

Opto-mechanical structural design for 8-12μm infrared dynamic thermal image simulator

针对常规红外动态热像模拟器光能利用率低,结构复杂,机加与装调困难,无法模拟地面目标及场景的问题,提出一种基于DMD调制的大视场、易装调、结构紧凑的长波红外动态热像模拟器。模拟器采用场镜与反射镜分离照明与投影光束,光能利用率约为TIR棱镜分光结构的2倍左右,同时针对两者的特殊位置设计了多维微调结构;为避免不同材料间热膨胀系数不同所引起的透镜光学表面受力不均,影响照明均匀性,对照明光学系统进行了热稳定结构设计;利用MATLAB求解出黑体的温度变化范围,并拟合出经光学系统前后辐射出射度的比值随温度变化曲线。温度测试与仿真实验表明,黑体温度从50℃变化为350℃的过程中,仿真背景温度漂移为8.1℃,约为模拟温差的7.84%,黑体温度为400℃时其图像对比度达到0.8以上,满足现阶段红外动态热像模拟器的使用要求。

Conventional infrared dynamic thermal image simulator has several shortages, such as low luminous energy usage efficiency, complicated structure, difficulty in machining and adjustment, and incapability in simulating the targets and scenes on the ground. In or- der to solve these problems, this paper proposes a long-wave infrared dynamic thermal image simulator based on DMD （ Digital Micro- mirror Device） modulation, which has the advantages of wide view field, easy machining and adjustment, and compact structure. The simulator uses the field lens and reflector to separate the lighting and projecting beams. The luminous energy usage efficiency is about as twice much as that of TIR （Total Internal Reflection） prism beam-splitting structure. Meanwhile, aiming at the special position of the field lens and reflector, the multi-dimension fine adjustment structure is designed. In order to avoid the fact that the different thermal ex- pansion coefficients of different materials cause uneven pressure on the lens optical surface and influence the illumination uniformity, the thermal stability structure of the illumination optical system is designed. The Matlab software is used to solve the temperature variation range of blackbody, and fit the variation curve of the radiant emittance ratio hefore and after the optical system vs. temperature. The temperature test and simulation experiment show that in the process of blackbody temperature changing from 50℃ to 350℃, the simula- ted background temperature drift is 8.1 ℃, which is about 7.84% of the simulated temperature difference. When the blackbody tempera- ture is 400℃, the image contrast reaches above 0.8, which meets current requirement of infrared dynamic thermal image simulator.