BRDF measurement of material surface at variable temperatures

A measurement system of bidirectional reflectance distribution function (BRDF) was developed based on the BRDF measurement principle of single reference measurement method, and it works at up to 500℃. Different angle position transfer was realized by a turntable device. The sample was heated by a furnace and the temperature was controlled by a fuzzy PID controller. The BRDF on a Cu surface was measured at the temperature of 25℃～500℃ by using a He-Ne laser as the light source whose wavelength was 0.6328μm and power was 8 mW. The Si1336-5BK photoelectric detector was selected for the measurement. The experiment shows that the measured value of BRDF on the Cu surface changes when the temperature on the sample surface is rising, and the BRDF value on the Cu surface is different when it increases or decreases to the same temperature. The forming mechanism of the phenomenon was analyzed. The conclusions can be used for further study on spatial reflectance characteristics of material surfaces.