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.

在神光Ⅱ系列装置中，为降低成本和减少示波器、快响应光电管等设备的使用，采用紫外光纤对高功率紫外纳秒激光脉冲进行取样并束测量。对高功率紫外纳秒激光脉冲在光纤中的传输特性和保真传输条件进行了理论分析和模拟研究，并据此选取了不同芯径的阶跃型紫外多模光纤进行实验研究。结果表明，对于芯径为25 μm的光纤，传输纳秒量级的紫外激光脉冲时畸变小，能进行较长距离传输，可以作为紫外激光脉冲的取样传输介质。利用芯径为25 μm的光纤演示了光纤取样传输并束测量实验方案，验证了光纤并束测量的可行性。研究结果为神光Ⅱ高功率紫外激光脉冲时间波形的光纤并束测量提供了理论和实验依据。

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。

为了准确测量皮秒量级超短脉冲的信噪比，扩大测量仪器的可测动态范围，针对高功率超短激光脉冲在相关过程中产生参量荧光的问题,研制了一台重复频率扫描测量的三阶相关仪，并在皮秒域短脉冲光学参量啁啾脉冲放大(OPCPA)抽运源上开展了测量技术研究。研究实验表明，通过采用大角度非共线匹配方式，消除了参量荧光对测量过程的影响，进而通过结构优化降低了背景噪声的影响，使可测动态范围达到107左右。由于互相关技术的非对称性，该测量系统可同时提供时间波形的分析功能。测量结果显示，激光脉冲前沿与双曲正割(sech)型曲线比较吻合，而脉冲后沿与高斯型曲线吻合得比较好。