三倍频分光膜在1064nm的破斑特性研究

Laser Damage Characteristic of Third Harmonic Separator at 1064nm

采用电子束蒸发方式制备了两种不同材料组合的分光膜,分别对其在波长1064 nm激光辐照下的损伤阈值进行了测试,用Alpha-Step 500台阶仪对破斑进行了深度测量。实验结果表明,破斑呈现出表面层的剥落和深坑破坏两种形态。表面层的剥落深度在一定范围内不随能量密度的变化而变化;深坑破坏深浅不一,是膜内缺陷融化、汽化及喷发的综合作用的结果,是损伤阈值降低的主要原因。

The two kinds of 3ω harmonic separator were prepared by electron beam evaporation with different materials. Laser induced damage threshold （LIDT） was measured at 1064 nm and the damage morphologies were mapped by Alpha-Step 500 meter. It was found that there are two different damage geometries： shallow denudation and deep crater. Shallow denudation in a certain range had same depth at different energy fluences, and material was removed from the top film layers. Deep crater had different depths caused by the combination of melting vaporization and fracture of inner defects of coatings, which was the main cause for decreased damage threshold.