Damage experiments are conducted by irradiating 351 nm laser near-filed to fused silica based on the damage threshold definition of near-filed irradiating. Damage areas are extracted 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 351nm laser near-field. This damage testing method is sample, quick, which can effectively decrease the effect of beam diameter for damage threshold due to the bigger aperture. The algorithm of image segmentation effectively removes the noise and suppresses the over-segmentation, and improves the accuracy of initial damage and damage growth. The research shows that the damage of fused silica is induced by 351 nm laser near-field with pulse width of 3.13 ns. The initial damage threshold is 2.94 J/cm2. With multiple irradiation of fused silica, the damage growth of exit surface is exponential, and the coefficient of damage growth is 0.32.

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.

针对351 nm激光诱导熔石英样品进行损伤实验。采用激光近场辐照样品，并基于近场辐照的损伤阈值定义方法进行损伤测试。利用带有灰度抑制的分水岭标记分割算法对损伤图像进行损伤区域提取，与相应近场分布进行比较，得到损伤区域边界点对应的局域能量密度即为损伤阈值。这种损伤测试方法简单、快速，有效降低了损伤阈值口径效应，且采用了能够有效去除噪声和抑制图像过分割问题的算法对损伤图像进行处理，使得到的损伤阈值和损伤增长系数有较高的准确性。实验结果表明，脉冲宽度为3.13 ns的 351 nm激光诱导熔石英样品的损伤阈值为2.94 J/cm2；在多次辐照样品情况下，熔石英样品出射面的损伤尺寸随着辐照次数的增加呈指数增长，其损伤增长系数为0.32。

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。

介绍了高功率激光系统的谐波转换系统匹配角调节的离线-在线技术。研究了如何将CCD近场仪应用于离线调节三倍频最佳匹配角, 该方案与光能量判断和肉眼观察光强相比更可靠。实验结果表明三倍频最佳匹配角的调节精度达到20″, 能够满足工程应用的要求。