光学系统性能的优劣与光学镜表面的散射情况息息相关.根据米氏理论并利用MATLAB软件，对可见光(0.632 8 μm)、近红外光(1.053 μm)和热红外光(10.6 μm)三种激光在干净、基本洁净(洁净度200)、轻度污染(洁净度500)及重度污染(洁净度750)四种光学镜面洁净度下镜面的双向反射分布函数进行了模拟计算.结果表明：光学镜面的表面粗糙度和表面洁净度影响镜面的双向反射分布函数.进而对光学系统的性能会产生显著的影响，且波长越短，双向反射分布函数越大，散射越复杂.这为光学工程中光学镜面的污染评估和镜面清洁提供有益帮助.

Performance of optical systems is closely related to the scattering characteristics of optical mirror surface. According to Mie theory, the bidirectional reflectance distribution function of optical mirror surface under four cases of mirror surface cleanliness levels such as clean, basic clean (cleanliness level 200), slight pollution (cleanliness level 500) and severe pollution (cleanliness level 750) was simulated and computed by MATLAB software when incident laser wavelengths are the visible light (0.632 8 μm), near infrared light (1.053 μm) and thermal infrared light (10.6 μm), respectively. The results show that the bidirectional reflectance distribution function of mirror surface is affected by mirror surface roughness and clean lines level, which will make a very important impact on properties of optical system. If wavelength is shorter, bidirectional reflectance distribution function will be greater, and scattering becomes more complicated. Useful help will be provided to estimate the pollution of optical mirror and clean the mirror surface in optical engineering.