光斑尺寸对K9玻璃近红外激光损伤阈值的影响

基于热弹性模型 ,用有限元法对不同光斑近红外激光辐照下K9玻璃样品中的温度和压力分布进行了计算。对厚 2mm、半径 10mm的圆片样品的计算结果表明 ,K9玻璃的损伤受表面环向拉伸应力的控制 ,光斑大小对损伤阈值有较大的影响 ,对光束总入射功率为 2 8kW的激光辐照 ,当光斑半径从 0 .4mm增加到 3mm时 ,损伤所需时间从 14ms增加到 1s。在一定光斑尺寸范围内 ,样品损伤 (表面拉伸断裂 )所需的激光功率密度在同一量级内变化 ,在更小光斑时 ,损伤时的最高温升趋于 5 6 5K。

Near-infrared Laser Beam Diameter Effect on Damage Threshold in K9 Glass

Based on thermal elastic constitution model,temperature and stress distributions in K9 glass samples irradiated with near infrared laser beams with various diameters were calculated using finite element method.Calculated results for circle plate sample of 2mm in thickness and 10mm in diameter show that circular tensile stress at sample surfaces dominates damage threshold,and laser beam diameter affects damage threshold cousiderably.For total irradiate power of 28kW,damage occurring time rises from 14ms to 1s when spot radius increases from 0.4mm to 3mm.In a certain range of spot size,laser intensities induced damage in samples varies in the same order.However when spot size beams smaller,damage is correlated with maximum temperature in samples.