熔石英表面激光损伤发展问题一直制约着激光器的运行通量。采用CO2激光在线熔融修复损伤点，修复后形成一个光滑的高斯坑，去除了损伤点中的裂纹，平滑了凹凸不平的表面，并且在紫外脉冲激光作用下，修复斑再次产生损伤的阈值高于熔石英元件的损伤生长阈值。因此CO2熔融修复技术能有效地抑制损伤发展。通过分析CO2激光作用下熔石英表面的温度分布，讨论修复坑的形成过程，确定激光参数对修复效果的影响，为寻找最佳修复参数提供理论基础。同时利用原子力显微镜(AFM)、轮廓仪细致分析损伤点和修复斑的微细结构，采用有限差分时域方法计算损伤点和修复斑周围的光强分布，探索消除裂纹和平滑表面对抑制损伤生长的作用。

Growth of laser induced damage on the surface of fused silica plays a major role in determining optics lifetime in high power laser systems. CO2 laser is used to mitigate the damaged spot. It locally meltes and evaporates the fused silica surface, producing smooth, Gaussian shaped pit, eliminating the cracks and rough, uneven on surface. Moreover, the damage threshold of mitigation spot is much higher than the damage growth threshold of fused silica. So CO2 laser mitigation treatment can successfully inhibit the growth of laser-induced surface damage on fused silica. The temperature distribution on the surface of fused silica induced by a CO2 Gaussian beam has been discussed to analyze the formative process of Gaussian shaped pits and determine the best mitigation parameter. Atomic force microscopy (AFM) and profiler are applied to observe the micro-structure of damage and mitigation spots. Finite-difference time-domain (FDTD) method is applied to calculate the light intensity distribution around the mitigation and damage spots. They provide useful information to understand the mitigation mechanisms.