激光辐照下薄膜镜面波纹损伤机理研究

 用透镜将脉冲激光束聚焦在铝膜镜面上，在部分样品的激光损伤边缘区，出现波纹状损伤形貌。大多数情况下，有多套波纹同时存在，在镜面形成花纹，或者其中有一两套波纹占优势。提出了脉冲激光辐照下光学元件损伤区边缘产生波纹的一种光干涉模型：认为样品表面本身存在微米级杂质颗粒或者表面缺陷点在激光辐照下首先产生鼓包变形，鼓包或杂质颗粒将激光反射（散射）在未发生变形的区域，与直接辐照在该区域的激光束产生干涉，使得变形区周围的光强呈周期性分布，当变形区进一步损伤后，则在损伤区周围留下了波纹状图案。模拟实验验证了这种设想。

Mechanism of laser induced ripple damage on a film mirror

Pulsed laser induced ripple damage on an aluminum film mirror has been investigated by experiments. Ripples have been found at the periphery of damage site by atomic force microscopy. In most cases, several set of ripples appear at the same time in the same area. A laser interference theoretical model has been presented to explain pulsed laser induced ripples at the periphery of damage site in optical surface. This model assumes that the impurity grain or laser induced sphere-like distortion at the surface of optical sample reflects or scatters laser beam to its periphery area, and this reflected or scattered beam interferes with the laser beam irradiated directly on this area. So the beam spatial profile becomes periodic and ripple damage morphology forms instantly. A simulated experiment is also presented to validate this assumption.