钛合金粗糙表面的偏振光及变温BRDF特性

基于红外光谱椭偏仪测得钛合金TC4在298~773 K范围的光学常数,结合Monte Carlo射线跟踪法对钛合金随机粗糙表面的双向反射分布函数(BRDF)进行了研究.分析了不同表面粗糙度、入射光偏振态及温度对钛合金表面BRDF分布的影响.结果表明:偏振光入射下钛合金的BRDF分布随入射角度及表面粗糙度的变化趋势与非偏振光相同;入射平面内粗糙钛合金表面的BRDF随光源偏振态变化与光滑平板具有相同趋势;TE波入射时的BRDF反射峰值大于TM波入射;钛合金粗糙表面的BRDF镜反射峰值随温度升高有下降趋势;在所研究的温度范围内(298~773 K),峰值变化在10.2%以内,温度变化对TM波下钛合金BRDF分布特性的影响大于TE波,且在入射角度增大时影响增大.

Polarization and temperature dependent BRDF of titanium alloy rough surface

Based on the measured optical constants of titanium alloy TC4 in temperature range 298~773K, the bidirectional reflectance distribution function (BRDF) of rough titanium alloy TC4 surface was studied by numerical simulation with the Monte Carlo raytracing approach. The effect of different polarized light incidence, different surface roughness and different temperature on BRDF distribution of rough titanium alloy surface was analyzed. The results show that, the change of BRDF distribution with the incident angle and the roughness of titanium alloy under polarized light is the same as that for unpolarized light. The BRDF of rough titanium alloy surface in incident plane changes with light polarization has the same trend with that of smooth plate. The BRDF peak under TE light incidence is greater than that of TM light. The BRDF peak in specular reflective direction of rough titanium alloy surface decreases with temperature increasing. In the temperature range studied in this paper (298~773 K), the peak changes within 10.2%. The effect of temperature on the BRDF distribution of titanium alloy under TM polarized light is greater than that of TE light, which increases with the increase of incident angle.