CO2激光对熔石英表面小尺寸损伤的修复

利用10.6 μm的CO2激光对不同直径的点状损伤和不同宽度的划痕进行了修复。经过波长351 nm的紫外激光考核发现，对于直径小于80 μm的点状损伤和对于宽度小于40 μm的划痕，随着损伤点尺寸和划痕宽度的增加，修复后阈值提高程度逐渐降低。划痕的宽度在达到40 μm以后修复效果非常微弱。修复过程中，由于作用时间较短及温度分布不均产生了热应力导致样片损伤以后产生径向裂痕，后续的紫外激光会使裂痕明显扩展。当样品被置于高温退火炉内退火3 h以后，应力导致开裂的现象得到了解决。

Small size damage mitigation on fused silica surface with CO2 laser

CO2 laser with 10.6 μm wavelength is used to irradiate damage of different types. Testing with 351 nm wavelength ultra-violet laser, it is found that for damage pits with size below 80 μm and scratchs with size below 40 μm, the larger damage size is, the less threshold enhancement of damage is. Mitigation is not distinct when the size of scratch is wider than 40 μm. During laser conditioning, heat stress results from short interaction time and asymmetrical temperature distribution, thus radial crack appears after damage and could expand if exposed to ultraviolet laser. After annealed in an oven for 3 hours, crack would not occur on the sample with damage.