光学与光电技术, 2008, 6 (1): 0022, 网络出版: 2010-06-08
脉冲激光烧蚀过程中靶材表面熔融前温度分布与激光功率密度分布的研究
Target Surface Temperature Distribution Before Melting and Pulsed Laser Power Density Distribution in the Pulsed Laser Ablation Process
摘要
用较为符合实际的高斯分布表示了脉冲激光输出功率密度分布,讨论了脉冲激光功率密度分布函数形状变化对烧蚀过程中靶材表面熔融前温度分布的影响。建立了考虑热源项的热传导方程,并给出了相应的边界条件。以Si为例,用有限差分方法模拟了温度随时间、位置的变化规律,模拟过程中强调了对边界条件的处理,使整体截断误差保持最小。通过改变脉冲激光功率密度分布函数的形状,分析了温度分布的变化。结果表明,相比恒定脉冲功率密度输出,功率密度高斯分布的激光束与靶材作用时高温阶段的温度变化率变大,靶材表面熔融时刻热扩散距离增加;当激光器上升沿变陡时,在有效作用时间内温度上升得更快,对加工区域周围热效应的影响明显减弱,而热扩散距离变小。
Abstract
The effect of the pulsed laser power density distribution function on the temperature distribution of the target surface before melting in ablation process is discussed with Gauss function standing for the pulsed laser power density distribution. The heat conduction equations considering heat resource are established, and the corresponding boundary conditions are given. Taking Si target as an example, the evolvement law of temperature varying with time and position is simulated by finite difference method. The boundary conditions treatments are emphasized to make the whole error keeping the least level in the simulation. The variation of the temperature distribution is discussed with the variation of the pulsed laser power density. The results show that comparing with the invariable pulse power density, the Gauss distribution results in faster temperature variety during the high temperature and the distance of the thermal diffusion will increase when the surface is melting.When the rise time is steeper, the temperature rises faster, and the surrounding of the machining filed are less affected while the distance of the thermal diffusion reduces.
张磊, 王秀凤, 林晓东. 脉冲激光烧蚀过程中靶材表面熔融前温度分布与激光功率密度分布的研究[J]. 光学与光电技术, 2008, 6(1): 0022. ZHANG Lei, WANG Xiu-feng, LIN Xiao-dong. Target Surface Temperature Distribution Before Melting and Pulsed Laser Power Density Distribution in the Pulsed Laser Ablation Process[J]. OPTICS & OPTOELECTRONIC TECHNOLOGY, 2008, 6(1): 0022.