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高灵敏度的红外光学系统中,系统自身热辐射成为影响系统探测性能的重要因素之一,而在一些应用低散射光学元件的散射敏感红外光学系统中,污染微粒经常是杂散辐射的主要来源。以卡塞格伦结构为例,利用ASAP光学分析软件,建立了红外望远镜系统的三维仿真模型。在此基础上,对反射镜干净、基本洁净(洁净度250)、轻度污染(洁净度500)及重度污染(洁净度750)4种情况下探测器像面上的系统自身热辐射通量进行了仿真计算,并基于有效发射率的概念对系统的杂散辐射性能进行了评价。最后,分别以镜面干净和重度污染为例,展开污染微粒对探测器像面上杂散辐射通量分布影响的讨论,利用标准差对像面上辐射通量分布的均匀性进行了评价。研究结果表明,污染微粒会轻微地改变探测器像面上的辐射通量分布,明显增大系统的有效发射率,显著降低系统的杂散辐射性能。因此,保持光学元件表面的清洁至关重要。
Highly sensitive infrared optics systems are one of the most important factors affecting the detection performance of the system. In some scattering-sensitive infrared optics using low-scattering optics, however, contaminant particles are often the main source of stray radiation. Taking Cassegrain as an example, a three-dimensional simulation model of infrared telescope system was established by using ASAP optical analysis software. On this basis, the self-radiant flux of the system on the image plane of the detector under the four conditions of clean mirror, cleanliness (cleanliness 250), light pollution (cleanliness 500) and heavy pollution (cleanliness 750) The simulation calculation is carried out and the stray radiation performance of the system is evaluated based on the concept of effective emissivity. Finally, taking the case of mirror clean and heavy pollution as an example, the influence of pollutant particles on the distribution of stray radiation fluxes on the image plane of the detector is discussed. The standard deviation is used to evaluate the uniformity of radiation flux distribution on the image plane. The results show that the pollutant particles will slightly change the radiation flux distribution on the detector image surface, significantly increase the effective emissivity of the system and significantly reduce the stray radiation performance of the system. Therefore, it is important to keep the surface of the optical element clean.