高对比度中/长波红外双波段视景仿真系统光学设计及测试实验

为了实现中/长波红外双波段制导系统的性能测试与评估，设计了一套基于数字微镜器件的红外双波段视景仿真光学系统，系统包括投影镜头和照明系统。利用非球面技术和大出瞳距、无穷远投影系统的像差特性，采用常规的红外材料，通过光焦度的合理分配与非球面像差校正的优势相结合，解决了双波段、大出瞳距离带来的彗差、像散、畸变和色差的平衡问题。采用阿贝式直接照明的方案，解决了斜入射情况下均匀照明的问题，有效地控制了杂光的影响，提高了光能利用率。设计结果显示:最终仿真系统全视场角为2，出瞳距离为250 mm，出瞳直径为70 mm，系统畸变小于0.2%，系统双波段的调制传递函数曲线均接近衍射极限；照明均匀性高于95%。系统实验测试表明:在黑体温度为300 ℃时，模拟温度最低为31.6 ℃，最高为250 ℃，温差为215.4 ℃，系统的对比度达到0.98，像面均匀性高于98.1%。仿真系统具有高对比度，宽温差和图像逼真的特点。

Design and testing of high contrast ratio MW/LW infrared dual-bands scene simulation system

For the requirements of performance testing and evaluation of IR guidence system which works in dual-bands of MW/LW, a DMD based dual-bands infrared scene simulation system was designed, including a projection lens and illumination optical system. The aberration characteristics of the aspherical surface and the projection system with long exit pupil relief and infinity projection was taken into account. Using common infrared materials with reasonable distribution of power and ashperical surface, it balanced the coma, astigmatism, distortion and chromatic aberration, introduced by the dual-bands and long exit pupil relief. In the design of the illumination system, directly irradiation combined with the Abbe illumination principle was adopted to achieve an uniform illumination in the case of oblique incidence, also the improvement of light energy utilization and suppression of the stray light as well. The design result shows that IR MW/LW scene simulator has a full field of view of 2, exit pupil relief of 190 mm, and exit pupil dimeter of 70 mm. The distortion of the lens is less than 0.2%, the modulation transfer function(MTF) is close to the diffraction limination at all the field of view in both the MWIR and LWIR; meanwhile, the relative illumination is higher than 95%. The test result shows, when blackbody temperature is 300 ℃, the lowest simulated temperature is 31.6 ℃, the highest temperature is 250 ℃, and the temperature difference reaches to 215.4 ℃, the system contrast ratio is higher than 0.98, and the relative illumination is higher than 98.1%. The simulation system has the characteristics of high contrast, wide temperature difference and realistic image.