针对红外光学系统元件表面缺陷问题, 基于米氏散射理论定量分析了不同疵病等级光学元件表面散射特性, 讨论了光学元件表面双向散射分布函数(BSDF)的变化规律, 进而建立光学元件不同疵病等级的散射模型。在此基础上, 以双子望远镜系统为例, 利用ASAP光学分析软件对其主镜在不同疵病等级的情况下, 到达探测器像面上的系统自身热辐射通量及其分布进行了仿真计算, 并根据有效发射率的定义, 对系统杂散辐射性能进行了定量评价。研究分析发现: 光学元件不同疵病等级不仅会造成系统杂散辐射特性及其在探测器像面上的辐射通量分布发生变化, 而且还会导致其有效发射率发生变化。对主镜疵病等级分别为0、 I-10、 I-20、I-30、II 和 III的情况, 计算得到系统有效发射率分别为2.19%、2.34%、2.46%、2.59%、2.72%和3.08%。由此可见, 随着疵病等级的增加, 系统杂散辐射性能逐渐降低。实际工作中, 必须严格控制光学元件表面疵病等级。

Aimimg at the problem of the defects on the surface of components in infrared optical systems, the scattering characteristics of optical components surface under different levels of defects were analyzed quantitatively based on Mie scattering theory. The variation of the bidirectional scattering distribution function(BSDF) on the surface of the optical component was discussed, and then a scattering model of optical components under different levels of defects was established. On this basis, a Gemini telescope was taken as an example, and the self-generated thermal radiation flux and its distribution of the system on the image plane was simulated quantitatively by using the ASAP optical analysis software for the case of the primary mirror under different levels of defects. Furthermore, according to the definition of the effective emissivity, the quantitative evaluation of the stray radiation of the system was carried out. The results indicate that the optical component under different levels of defects not only alter the stray radiation flux and its radiation distribution of the system on the image plane, but also change its effective emissivity, the effective emissivity of the system is 2.19%, 2.34%, 2.46%, 2.59%, 2.72% and 3.08% respectively when primary mirror defect levels under six cases such as 0, I-10, I-20, I-30, II and III. Thus, the stray radiation performance of the system decreases with the increasing of the level of the defects. Consequently, the levels of defects on the surface of the optical component should be strictly controlled in the practical applications.