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光学镜面的散射对光学系统的性能有十分重要的影响。选用可见光0.6328μm、近红外光1.053μm和热红外光10.6μm三种激光波长,利用修正的米氏理论和光学表面的双向反射分布函数(BRDF)研究光学镜面在不同污染条件下激光的传输特性。研究结果表明:当镜面粗糙度远远小于入射光波长(σ<<λ)时,干净镜面的散射强度与σ成正比,与λ成反比。污染镜面散射强度与污染颗粒的尺寸和数量有关,颗粒分布越复杂,散射越显著。另外,波长越短,BRDF越大,散射越复杂。
Optical specular scattering has a very important effect on the performance of the optical system. The wavelength of visible light 0.6328μm, near infrared light 1.053μm and thermal infrared light 10.6μm were selected. The modified Mie theory and the birefringence distribution function (BRDF) of optical surface were used to study the transmission characteristics of laser under different pollution conditions . The results show that when the mirror roughness is far less than the wavelength of incident light (σ << λ), the scattering intensity of a clean mirror is proportional to σ and inversely proportional to λ. The intensity of the contaminated speckle scattering is related to the size and amount of polluted particles. The more complicated the particle distribution, the more significant the scattering. In addition, the shorter the wavelength, the larger the BRDF and the more complicated the scattering.