Plasma modulation effect of beam shaping to improve signal quality of laser induced breakdown spectroscopy
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 commonly used Gaussian profile to flat-top profile. With a more homogeneous distribution of laser power density, the flat-top beam was expected to achieve 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 over high laser power at the center of the laser beam, which would lead to stronger signal. Results showed that using 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 Mg(I) 285.21 nm line was reduced from 33% to 18% for the laser energy of 30mJ, and the signal intensity was enhanced to 1.5 to 3.5 times for different laser energy. Overall, plasma modulation using beam shaping was proved to be very effective in improving LIBS signal quality.