弱散射体的宽谱BRDF测量与分析

弱反射体粗糙表面具有复杂的散射现象.随着入射光天顶角的增加,这类弱反射体的光反射由方向性漫散射过渡到镜面反射,且波长不同的反射光出现不同强度的镜面反射.为了研究这个波动光学现象,使用一台宽谱全向反射计测量了两个弱反射体样品在多个可见波长的双向反射分布函数;使用一台探针式表面轮廓仪测量了样品的表面轮廓,进而获得了样品表面统计特性.一个基于波动光学的BRDF模型通过拟牛顿法优化算法逐次逼近被拟合到测量数据,准确地描述了散射光随角度和波长的变化.通过拟合结果和测量数据比较,证明基于波动光学的BRDF模型适用于解释该现象.

Broad-Band BRDF Measurement and Analysis of Weak Scatterers

Complex wave-optics scattering phenomenon exists on the surfaces of the weak scatterers. With the increase of the incidence angle, the light scattering from such a surface varies from directional diffuse scattering to mirror reflection, while the magnitude of mirror reflections varies with the wavelengths. To study the phenomenon, a broad-band gonioreflectometer was used to measure the bidirectional reflectance distribution functions (BRDFs) of two weak scatterer at various wavelengths; on the other hand, a stylus profilometer was used to obtain the surface height data and, furthermore, the statistical characteristics of the rough surfaces. A wave-optics BRDF model was fitted to the measured data with Quasi-Newton optimization algorithm, and accurately predicted the correlation of the scattered light with the angles and the wavelengths. By comparing the fitting results and the measured data, we prove that the phenomena can be predicted accurately with the wave-optics based model.