为保证空间相机热设计中表面辐射换热计算准确可靠, 基于两种金属材料的光学常数, 结合Monte Carlo射线跟踪法应用几何光学近似对其粗糙表面的双向反射分布函数(BRDF)进行了研究。分析了不同入射光波长、不同入射角度及不同表面粗糙度对金属铝和钛材料粗糙表面的BRDF的影响。结果表明, 金属铝和钛材料粗糙表面的BRDF分布具有明显的镜反射特征, 入射平面内的BRDF峰值随入射光波长增加而增大, 在本文研究的波长范围内, 钛表面的BRDF随入射光波长增大的增幅最高达到41.0%, 远高于铝表面的8.7%。当表面粗糙度较大时, 光子在粗糙表面内会经历多次散射, 粗糙表面内多次散射光子数比例随着表面粗糙度的增大而增加, 并且随着入射角度的增大具有增加的趋势。

In order to guarantee the accuracy and reliability in calculation of surface radiative heat transfer in thermal design of space camera, based on the optical constants of two metal materials, the bidirectional reflectance distribution function (BRDF) of their rough surfaces was studied by using the geometrical optical approximation and Monte Carlo ray tracing method.The influence of wavelength of incident light, incident angles and surface roughness on the BRDF of rough surface of aluminum and titanium is analyzed.The results indicate that the distribution of BRDF on rough surface of aluminum and titanium material has clear mirror reflection characteristic, the peak value of BRDF in the incident surface increases with the wavelength increasing of incident light, in the range of wavelength studied in this paper, BRDF of the titanium surface increasing with the wavelength of incident light increases up to 41.0%, far higher than 8.7% of the aluminum surface.When roughness is larger enough, the photon will experience multiple scattering in the rough surface, the ratio of multiple scattering photons in the rough surface increases with the surface roughness increasing, and has increasing trend as the incident angle increases.