重复率激光作用下光学薄膜损伤的累积效应

使用脉宽12 ns,频率10 Hz的1064 nm调Q NdYAG激光器,研究了高反射膜在重复率激光作用下的损伤的累积效应.实验发现,高反射膜的损伤阈值随辐照脉冲数增加而降低,表现出明显的累积效应.通过对损伤阈值和损伤概率以及辐照次数的统计性研究,并结合单脉冲辐照的结果,说明了存在于薄膜中微小的缺陷参与了多脉冲激光对薄膜的损伤过程.可用预损伤机制解释实验结果.得到了关于IBS制备的高反射膜的损伤阈值和照射次数的关系式,并用实验结果进行验证,发现具有很好的一致性.实验过程中样品的损伤形貌通过Nomarski偏光显微镜进行了观察,发现是典型的缺陷损伤.

Accumulation effect of multi-shot laser-induced damage to optical coatings

The accumulation effect of multi-shot laser-induced damage to optical coatings was investigated. Laser damage testing was performed at 1 064 nm with nanosecond pulses at a pulse length of 12 ns, using an accurate and reliable measurement system. The damage threshold and the number of shots were studied by a statistical method. Compared with the case of single shot laser damage, it is concluded that the microdefects in the optical coatings are responsible for the multiple-pulse damage to mirrors. The damage mechanism can be used to explain the damage process. The expressions for the damage threshold and the number of shots are founded. Nomarski microscope was employed to observe the laser-induced damage morphology after laser irradiation.