在激光破坏机理研究中,经常关注材料对入射激光的反射率随辐照面温度的变化规律。利用基于积分球法的反射率测量系统,测量了915nm激光辐照下45#钢对3.8μm探针光的反射率的变化,确定了探针光辐照区的温度变化。结果表明,反射率的快速减小是由高温下样品表面快速氧化导致的,反射率随温度的缓慢变化是由电导率随温度变化导致的。 In the research of laser damage mechanism, the regularity of reflectivity of incident laser with the temperature of irradiated surface is often concerned. The reflectivity measurement system based on the integrating sphere method was used to measure the change of the reflectivity of 3.8μm probe light of 45 # steel irradiated by 915nm laser and the temperature change of the probe irradiated area was determined. The results show that the rapid decrease of reflectivity is caused by the rapid oxidation of the sample surface at high temperature, and the slow change of reflectivity with temperature is caused by the change of conductivity with temperature.