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采用不同光斑直径的10.6μm CO2激光束对熔石英表面损伤进行辐照处理。实验发现,对于50μm以下的损伤点,单发激光脉冲辐照即可使得激光损伤阈值恢复到基底完好区域的水平,对于在50~300μm之间的损伤点,采用低功率较长时间辐照后逐渐增加功率修复的方式可以彻底消除材料内部更深的裂痕。对不同尺寸光斑辐照后的应力分布研究表明,激光束尺寸、激光功率和激光作用时间是影响材料体内应力分布的主要因素,相比较而言,激光尺寸对应力分布的影响更为明显。对前后表面损伤分析表明,当辐照区域置于入射面时,辐照带来的微小环状凸起会造成后表面环形调制损伤,是损伤的最薄弱环节,当辐照区域置于后表面时,烧蚀主要影响阈值的整体提升。
The surface damage of fused quartz was irradiated by 10.6μm CO2 laser beam with different spot diameter. Experiments showed that for the damage point below 50μm, single laser pulse irradiation can make the laser damage threshold returned to the level of the substrate intact area, for the damage point between 50 ~ 300μm, after a relatively low power for a long time after irradiation A gradual increase in power recovery can completely eliminate deeper cracks in the material. The research on the stress distribution of different size spots shows that laser beam size, laser power and laser action time are the main factors that affect the stress distribution in the material. In contrast, the effect of laser size on the stress distribution is more obvious. The analysis of the front and back surface damage shows that when the irradiation area is placed on the incident surface, the tiny annular protrusion caused by the irradiation will cause ring modulation rear surface damage, which is the weakest link of the damage. When the irradiation area is placed on the back surface When ablation mainly affects the overall improvement of the threshold.