基于分数泰伯效应的激光损伤阈值测量

Fractional Talbot effect based measurement of laser-induced-damage thresholds

介绍了一种基于分数泰伯效应的单脉冲激光损伤阈值测量方法。该方法是根据六角相位光栅的分数泰伯效应,将激光光束整形成许多不同能量密度的高斯形状光斑,通过比较光斑分布图和损伤分布图即可统计计算得到各个能量密度区间的损伤概率。根据角谱传输理论数值模拟得到了六角相位光栅的分数泰伯像并得到实验验证。用该方法和传统的1-on-1测得HfO2/SiO2高反介质膜的激光零损伤阈值分别为7.9和8.0 J/cm2,并进行了误差分析。

A method based on fractional Talbot effect is studied for single-shot measurement of laser-induced damage threshold. Using hexagonal phase grating, a laser beam is transformed into an ensemble of Gaussian-like spots with different energy densities at the test sample. Therefore, a statistical determination of the damage threshold of thin-film coatings can be performed by comparison of the intensity distribution with the damage pattern. Basic theories about the spectrum transmission and the frac- tional Talbot self-imaging are applied to calculating the Fresnel image of the hexagonal phase grating, and the results are testified by experiment. The laser-induced damage thresholds of HfO2/SiO2 coating sample measured by this method and the traditional 1- on-1 method are 7.9 J/cm^2 and 8.0 J/cm^2 , respectively. The errors of the single-shot measurement are analyzed.