近阈值能量密度下薄膜的激光损伤特点

Laser damage mechanisms of optical coating under near threshold energy

采用毫米量级大光斑的近单模的激光器 ,控制入射薄膜表面的激光能量 ,获得了几种常见单层膜和增透膜的损伤形貌 ,实验结果表明 ,薄膜的损伤可区分为熔化型和应力型两种 ,薄膜表面等离子体对损伤斑点的扩大有重要作用。

A laser damage facilities,which has mm size spot and operates in TEM 00 mode, were achieved.In order to know the reasons of laser damage,the laser energy density was controlled near the damage threshold of the oxide thin films.According to the examined near threshold damage morphology,the damage mechanisms of the optical coatings can be divided into two types.One was caused by melting of the coating materials,another by exploding,induced with the inner stress of the film.The plasma generated was an important reason to expand the damage area.