为了研究污染颗粒对光学系统镜面散射的影响, 将光学镜面暴露在室内, 得到三种不同污染程度的镜面, 利用电子显微镜表征三种污染镜面的颗粒分布。使用光束质量分析仪采集洁净镜面和三种不同颗粒污染镜面的镜向散斑图像, 结合双向反射分布函数(BRDF)对其从水平和垂直方向进行分析。研究结果表明, 不同入射角下, 颗粒污染镜面的镜向BRDF值都在同一个数量级；从水平和垂直方向分析, 颗粒尺寸越大, 颗粒数量越多, 镜向BRDF的中心变化较小, 边缘起伏较大, 镜面散射越严重。

Three different kinds of contaminated mirror exposed to indoor are obtained to study the influence of contaminated particles on mirror surface scattering in optical system. Particulate distributions of three contaminated mirrors are characterized by an electron microscope. A beam quality analyzer is used to collect the specular speckle images of clean mirror and three different contaminated mirrors and the images are analyzed in horizontal and vertical directions with bidirectional reflectance distribution function (BRDF). Research results show that the specular BRDF values of particulate-contaminated mirrors with different incident angles are in the same order of magnitude. From horizontal and vertical directions, the larger is the particle size, the more is the number of particles, the center of the specular BRDF changes slightly, the edge of them are volatile, and the mirror surface scattering will be more serious.