空间目标表面材料光谱双向反射分布函数测量与建模

介绍了双向反射分布函数（BRDF）的绝对测量原理和方法，选用光谱分辨率为3 nm的光谱辐射度计及精度为001°的三维转角系统，搭建了BRDF自动测量平台，对空间目标表面包覆材料在400—2500 nm的光谱BRDF进行了测量.结果表明，BRDF曲线极大值所对应的散射角度一般在镜反射方向左右，其余BRDF值随散射角变化很平缓，从中间向两边逐渐变小，近似成余弦分布.测量误差为495%.应用模拟退火算法，结合BRDF五参量统计模型，获得了测量光谱范围内各波长对应的共2101组五参量值，通过对比参量计算结果和 关键词： 双向反射分布函数 绝对测量 误差分析 参量模型

Measuring and modeling the spectral bidirectional reflection distribution function of space target's surface material

An absolute measuring principle and method of bidirectional reflection distribution function(BRDF)is presented.A spectral radiation meter with 3 nm spectral resolution and a three-dimensional rotating system with 0.01°accuracy are utilized to establish the automatic measuring platform.The spectral BRDF of typical space target's surface materials (yellow and silver tinfoil)is measured in the range of 400-2500 nm.Measured results show that the scattering angle,which corresponds to the maximum value of BRDF curve,is generally in the specular reflection direction;the other BRDF values change slowly as scattering angle varies,declining from middle to both sides and approximately following the cosine distribution.A BRDF error analysis method is introduced by using the RMS error calculation,which provides a new way for the BRDF measurement system evaluation.The measurement error is 4.95%.With five-parameter model of BRDF and the simulated annealing(SA)algorithm,the optimum parameters of the model at each wavelength in the measured spectrum are retrieved at intervals of 1 nm.A comparison of the data calculated by the parametric model with the data measured originally verifies the feasibility and reliability of the modeling.The measuring and modeling results can provide reference data for space target detection and identification.