Experimental Study of Multiple Wavelength Laser-Induced Damage in Si02 Based on Near Field and Image Segmentation

在复合波长(波长分别为1053、527、351 nm)情况下,利用激光近场对熔石英样品进行损伤实验。设计了一种基于激光近场辐照的损伤阈值定义方法,并利用带有灰度抑制的分水岭标记算法对损伤图像进行损伤区域提取,通过对比损伤图像与相应光束近场能量分布,计算出损伤区域与非损伤区域临界处的光能量密度,即为熔石英样品的损伤阈值。实验结果表明,复合波长激光诱导熔石英损伤是3种波长激光共同作用的结果,但351 nm激光对损伤起主要作用,初始损伤阈值为8.22 J/cm2;在复合波长激光多次辐照样品的情况下,熔石英样品后表面的损伤成指数形式增长,损伤增长系数为0.59。Damage experiments are conducted by irradiating fused silica with the multiple wavelength laser near field. The multiple wavelength laser consists of 1053、 527、 351 nm laser. It designs a definition of damage threshold based on laser near-field irradiation and extracts damage areas from damage images by the marker-based watershed algorithm with gray control. The initial damage threshold is defined as the fluence of critical site between damage region and no damage region, which is calculated by comparing the damage image with the multiple wavelength laser near field. The research shows that the damage of fused silica is induced by the three wavelength lasers. The 351 nm laser plays a leading role. The initial damage threshold is 8.22 J/cm2. With multiple irradiation of fused silica in multiple wavelength laser, the damage growth of exit surface is exponential, and the coefficient of damage growth is 0.59