用光声信号飞越时间法对纯铜脉冲激光烧蚀的研究

Pulsed-laser ablation of pure copper using TOF of photoacoustic signals

利用脉冲激光束轰击金属样品表面时在周围空气中激发的光声信号研究了纯铜的激光烧蚀。实验中,用He-Ne探测光束偏转方法检测光声信号,并根据光声信号飞越时间随激光能量密度的变化测定了纯铜的脉冲激光烧蚀阈值。文中还给出了一种理论估计脉冲激光烧蚀阈值的较为实用的方法。纯铜的脉冲激光烧蚀阈值的实测值约为3.0 J/cm2,理论估计值为3.2 J/cm2。两者符合较好。结果表明,光声信号方法是测定纯铜的脉冲激光烧蚀阈值的一种简单可行的方法。

Laser ablation of pure copper was investigated using photoacoustic signals excited in surrounding air when a pulsed-laser beam impinges a metallic surface. The photoacoustic signals were detected by means of deflection of a He-Ne probe beam in the experiment. The pulsed-laser ablation threshold of pure copper was determined according to the variation of the time-of-flight （TOF） of photoacoustic signals with the laser energy. A more practical method for theoretical evaluation of pulsed-laser ablation threshold is given in the paper. The measured pulse-laser threshold of pure copper was about 3.0 J/cm^2, which is closed to the theoretical value of 3.2 J/cm^2. It has been shown that the method of TOF of photoacoustic signals is reliable and simple for determining pulsed-laser ablation threshold of pure copper.