S-on-1测量方式下薄膜激光损伤的累积效应

为了研究薄膜激光损伤机理及影响因素，基于平顶光束辐照测量的原理，采用1064nm的Nd:YAG激光器，对电子束热蒸发方式镀制的HfO₂薄膜在重复频率激光作用下损伤的累积效应进行了理论分析和实验验证。运用损伤阈值的测量原理，分析了1-on-1和S-on-1两种测量方式的特点，并分别开展了测量实验。采用二分法查找辐照激光能量，每个能量密度辐照20个测试点，应用零几率损伤阈值和最小二乘法拟合确定测量结果。结果表明，对同种薄膜，1-on-1测量方式测得的损伤阈值为15.75J/cm2，S-on-1测量方式测得的损伤阈值为11.90J/cm2；从损伤阈值与损伤形貌两方面的对比表明，S-on-1测量方式体现了典型的累积效应。此结果对深入研究薄膜激光损伤的机理和影响因素具有重要意义。

Cumulative effect of thin film laser damage under S-on-1 measurement mode

In order to study the damage mechanism and influencing factors of laser thin films, the principle of radiation measurement based on flat top beam was proposed. The cumulative damage effect of HfO₂ films processed by electron beam thermal evaporation under the repeated frequency laser irradiation was studied by using 1064nm Nd:YAG laser. After theoretical analysis and experimental verification, the characteristics of two measuring methods, 1-on-1 and S-on-1, were analyzed based on the measuring principle of damage threshold. The irradiation laser energy was seeked by dichotomy. Each energy density was irradiated at 20 test points. Zero probability damage threshold and least square method were used to fit and determine the measurement results. The results show that for the same kind of film, the damage threshold measured by 1-on-1 method is 15.75J/cm2 and the damage threshold measured by S-on-1 method is 11.90J/cm2. The comparison of damage threshold and damage morphology shows that S-on-1 measurement method reflects the typical cumulative effect. The study is of great importance for the study of laser damage mechanism and influencing factors of thin film.