Simulation and Experimental Study on the Scattering Properties of Two Dimensional Rough Surfaces
|School||Harbin Institute of Technology|
|Keywords||scattering properties surface topographic roughness Bi-Directional Reflectance Distribution Function (BRDF)|
Light scattering is one of the most important natural phenomenon, and has very wide range of applications. In this dissertation, light scattering from rough surfaces is systematically investigated by numerical simulation and experiment. Main research works are as follows:1. Based on geometric optics approximation, light scattering from two dimensional rough surfaces was simulated by Monte Carlo method, considering the shadowing effect of incidence and the multiple reflections, also with the depolarization in surfaces scattering, the traditional ray-tracing algorithms are improved.2. Scattering properties of some typical materials were investigated by experimental measurements: first we learned the surface scattering properties of satellite coating; then analyzed the temperature affect on the scattering properties of Cu, PTFE and graphite; the bidirectional reflectance function (BRDF) of granite with dry/wet surfaces were measured in BRDF experimental device, results show that the BRDF of granite is largely affected by the dry/wet status, and there exits obviously mirror reflection component when the surface is wet.3. Characteristics of real surfaces were analyzed according to the surface topographic data, measured using an atomic force microscope (AFM) for a rough granite surface. Height distribution of real surface is not completely Gaussian, showing slightly anisotropy. The surface topographic data are implanted into Monte Carlo method to model the in plane BRDF at the wavelength of 0.6328μm, the modeling results were compared with the measurements, we can get reasonable agreement between them.4. Several factors: wavelength, shield, multiple reflections and distribution of local incidence angles that affected the emissivity of rough surface were systematically investigated. Research shows that: emissivity of ideal plane is determined by incidence angles and physical characteristics of the medium; emissivity of rough surfaces will be changed because of the multiple reflections; the shield probability may be affected by the change of incidence angles and roughness, which lead to the change of multiple reflections and the distribution of local incidence angle, variety of factors working together result in the emissivity of rough surfaces showed increase after the first decrease with the increasing incidence angles and increase with the increasing roughness.Scattering properties of rough surfaces are studied throw numerical simulation and experimental measurements, the main factors that affected light scattering from rough surfaces are systematically analyzed and discussed.