Effect of laser beam shaping on the determination of manganese and chromium elements in steel samples using laser-induced breakdown spectroscopy

To investigate the effect of laser beam shaping on the determination of manganese (Mn) and chromium (Cr) elements in steel samples with different matrices using laser-induced breakdown spectroscopy (LIBS), a commercial beam shaper was used to convert the Gaussian laser into a top-hat laser. Owing to the uniform beam energy distribution and the less unwanted heating, the crater produced by the top-hat laser is much flatter and smoother than that produced by the Gaussian laser. The leave-one-out cross-validation (LOO-CV) method was used to evaluate the predictive capability of the calibration models. After laser beam shaping, the determination coefficient (R2) values of the calibration curves were slightly improved, and the root mean squared error of cross-validation (RMSECV), relative error (RE), relative standard deviation (RSD), and the limits of detection (LOD) values were all about 2 times reduction. The results indicate that the laser beam shaping method is an effective approach to reduce the matrix effect and improve the repeatability and accuracy of LIBS.