使用衍射光学元件将高斯激光光束整形为能量分布均匀的平顶激光光束,对比了两种激光诱导铜等离子体的特性,研究了光束整形对激光诱导击穿光谱稳定性的改善作用。研究结果表明:激光光束能量分布的均匀性引起了烧蚀坑形貌以及单次烧蚀量的差异,高斯激光和平顶激光诱导光谱的强度、等离子体温度和电子密度的相对标准偏差分别为12.33%和6.37%、2.10%和1.32%、5.31%和0.65%;光束整形后激光诱导击穿光谱的稳定性得到了明显改善,两种激光诱导产生的等离子体均呈局部热力学平衡状态。

The Gaussian laser beam is shaped into a flattop laser beam with uniform energy distribution by a diffractive optical element. The Cu plasma characteristics induced by two lasers are compared, and the improvement of the beam shape modification on the stability of laser-induced breakdown spectrum is studied. The research results show that the uniformity of beam energy distribution causes the difference in the morphology of the ablation crater and single-shot ablation amount. The relative standard deviations of the Gaussian laser and the flattop laser induced spectra intensity, plasma temperature and electron density are 12.33% and 6.37%, 2.10% and 1.32%, 5.31% and 0.65%, respectively. The stability of the laser-induced breakdown spectrum after beam shaping is significantly improved, and the two laser-induced plasmas are all in the local thermodynamic equilibrium state.