光学窗口材料激光辐照热-力效应的解析计算研究

Calculation of Thermal and Mechanical Effect Induced by Laser in Optical Window Materials

建立了高功率连续激光辐照透明光学材料的热力学模型,通过积分变换方法求解三维热传导方程,得出了激光辐照引起的瞬态温度场分布的精确解析解,并在此基础上进一步求得热应力场的瞬态分布。以1.315μm的高能氧碘激光辐照熔石英玻璃为例,计算了熔石英在激光辐照下的温度场与热应力场分布,分析了其激光损伤机理。研究结果表明由于熔石英具有优良的热稳定性,温度不均匀分布所产生的热应力相对较小,激光损伤主要是受辐照区域温度值超过材料熔点发生熔融破坏。理论分析结果与相关的实验结论一致,说明所建立激光辐照效应模型的合理性。

The thermal-mechanical model of transparent optical materials induced by high-power continuous laser is set up and the precise resolution of transient temperature field distribution induced by laser is obtained through resolving the 3-dimensional heat conduction equation using integral-transform method. On the base of the above analysis, the thermal stress field transient distribution induced by laser is worked out. Taking fused silica irradiated by 1. 315 μm high-power chemical oxygen-iodine laser （COIL） as an example, the fused silica temperature field and thermal—— stress field transient distributions irradiated by COIL laser are calculated and the laser induced damage mechanism is analyzed further. The calculation result shows that the laser induced damage is mostly melt damage in the areas where temperature exceeds melt point of fused silica. Because fused silica has a fine thermal stability, the thermal stresses induced by the temperature ununiformity are small relatively. The theoretical analyzing result is in accordance with the relative experimental result, so the laser irradiation effect model proves correct.