Variable temperature BRDF measurement up to 1000 °C for highly reflective surfaces

Bidirectional Reflectance Distribution Function (BRDF) under variable temperature conditions is important for target identification and stealth in aerospace applications of highly reflective materials. In this paper, a variable temperature BRDF measurement system based on a robotic arm with an ingenious heater is designed. For BRDF measurements of highly reflective surfaces, a scanning strategy with variable angle intervals in continuous space is proposed to improve the resolution near the maximum BRDF and to reduce the measurement time. An ingenious heater is designed to be mounted on the robotic arm to move in space and heat a sample. The measurement uncertainty of the proposed variable temperature BRDF of highly reflective materials is discussed, which has been divided into the components of laser intensity fluctuations, scanning speed and heating stability. The effectiveness of the measurement system was verified by the variable temperature BRDF measurements during two heating processes on a highly reflective stainless-steel sample.