脉冲CO_2激光辐照K9玻璃的热力效应分析

Thermal and Mechanical Damage in K9 Glass Irradiated by Pulse CO_2 Laser

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。

A numerical simulation was performed to calculate temperature and stress distribution in K9 glass sample irradiated by pulse CO2 laser using finite element method. The simulation results indicated that for a circle plate sample of 20 mm in radius and 2 mm in thickness the damage threshold was dominated by circular stress, damage was initialized inside the K9 glass sample, and laser beam radius affected damage threshold considerably. The damage threshold of K9 glass irradiated by single pulse CO2 laser was 0. 5 J. The damage threshold increased with the beam radius increasing, and decreased with the number of laser pulse increasing. The damage effect influenced by the size of K9 glass sample was investigated. It is shown that the radius and the thickness of K9 glass sample affect stress damage considerably. The optimal radius of K9 glass is from 10 mm to 20 mm.