本文研究了强激光辐照下漫反射金膜在近红外波段的反射特性, 建立了漫反射金膜表面反射率在线测试系统, 得到了不同激光参数辐照下膜层表面反射率变化曲线。检测了金膜表面氧化产物的主要成分, 给出了氧化产物的生成机理。根据氧化理论和单层膜反射理论建立了金膜表面反射率变化计算模型, 并基于该模型分析了膜层氧化对激光辐照温升的影响。结果表明: 强激光辐照下漫反射金膜表面生成了一层光学薄膜, 组分为NiO, 生成速率满足对数定律; NiO薄膜对入射激光的吸收是金膜表面反射率下降的主要原因, 而且辐照光强越强膜层氧化越快。

To investigate the reflective characteristics of diffusing gold film irradiated by high power lasers, an online testing system was set up to deduce the films′ reflectivity variation with different laser irradiation parameters. The elements of the oxidation products were analyzed and an oxidation mechanism for a diffusing gold film was proposed. A numerical model for the reflectivity of a gold plating film under high power laser radiation was built using oxidation theory and single-layer reflection theory. With this model, the influence of film oxidation on the temperature rise from laser irradiation was analyzed. The results show that the oxidation product is NiO, the dynamic curve of the oxidation of the gold film follows the law of logarithms and the degradation of the reflectivity of the gold film results from the absorption-enhancement effects induced by the NiO film. Moreover, the stronger the intensity of the irradiation, the faster the oxidation of the film.