Uncertainty reduction is of great importance for laser-induced breakdown spectroscopy (LIBS). In this work, we modulated the evolution of the laser-induced plasma by shaping the laser beam from a commonly used Gaussian profile to a flat-top profile. With a more homogeneous distribution of laser power density, the flat-top beam was expected to achieve a more stable plasma morphology by more uniform ablation, which would lead to higher repeatability of LIBS signals, and to reduce plasma shielding effects by avoiding excessively high laser power at the center of the laser beam, which would lead to stronger signals. The results showed that by using a flat-top beam, the aluminum–magnesium alloy plasma morphology was meliorated with a larger and more stable plasma core, the relative standard deviation (RSD) of the Mg(I) 285.21 nm line was reduced from 33% to 18% for a laser energy of 30 mJ, and the signal intensity was enhanced 1.5 to 3.5 times for different laser energies. Overall, plasma modulation using beam shaping was proved to be very effective in improving LIBS signal quality.

中文翻译：

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使用光束整形的等离子体调制可改善激光诱导击穿光谱的信号质量

降低不确定度对于激光诱导击穿光谱法（LIBS）至关重要。在这项工作中，我们通过将激光束从通常使用的高斯轮廓成形为平顶轮廓来调制激光诱导的等离子体的演变。随着激光功率密度的分布更加均匀，期望通过更均匀的烧蚀实现平顶光束更稳定的等离子体形态，这将导致LIBS信号具有更高的重复性，并通过避免过高的激光来降低等离子体的屏蔽效果激光束中心的功率，会产生更强的信号。结果表明，通过使用平顶光束，铝镁合金的等离子体形态被改善，并具有更大，更稳定的等离子体核心，Mg（I的相对标准偏差（RSD））对于30 mJ的激光能量，285.21 nm线从33％降低到18％，并且对于不同的激光能量，信号强度提高了1.5到3.5倍。总的来说，使用波束整形的等离子体调制被证明对改善LIBS信号质量非常有效。