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利用有限元法对脉冲CO2激光辐照K9玻璃样品中的温度和应力分布进行了数值分析。对半径为20mm、厚为2mm的圆盘样品的计算结果表明,K9玻璃的损伤由环向应力控制,体损伤先于面损伤产生,且光斑半径和脉冲数目对损伤阈值有较大的影响,在激光光斑半径为5mm,脉宽为10μs的条件下K9玻璃的单脉冲CO2激光的损伤阈值为0.5J,相应的能量密度为0.637J/cm2。损伤阈值随光斑半径的增大而增大,随脉冲数目的增加而变小。讨论了样品半径和厚度对损伤结果的影响,结果表明样品半径在10～20mm范围内所产生的拉伸应力较小。
The temperature and stress distribution in K9 glass irradiated by pulsed CO2 laser were numerically analyzed by finite element method. The calculation results of a disc sample with a radius of 20 mm and a thickness of 2 mm indicate that the damage of the K9 glass is controlled by the circumferential stress, the body damage occurs before the surface damage, and the spot radius and the number of pulses have a greater impact on the damage threshold. Under the laser spot radius of 5mm and the pulse width of 10μs, the damage threshold of single-pulse CO2 laser of K9 glass is 0.5J and the corresponding energy density is 0.637J / cm2. The damage threshold increases with the increase of spot radius and decreases with the increase of pulse number. The effects of sample radius and thickness on the damage results are discussed. The results show that the tensile stress is small when the sample radius is in the range of 10 ~ 20mm.