Iterative multi-energy calibration and its application in online alloy smelting process monitoring using laser-induced breakdown spectroscopy

This report proposes an iterative multi-energy calibration (IMEC) method for online alloy smelting process monitoring and describes its performance verification on laser-induced breakdown spectroscopy (LIBS) online monitoring equipment in application factories. The proposed IMEC method is an improvement upon the existing MEC method, it involves two stages: standard sample preparation and implementation of a quantitative analysis algorithm. Compared with the internal standard (IS) method, the average root mean square error (RMSE) and relative standard deviation are improved from 0.19 wt.% to 0.11 wt.% and from 2.2% to 1.1%, respectively. To evaluate the IMEC performance more scientifically, a ‘bootstrapping’ method was employed, in which 10,000 sets of data sequences were reconstructed from real data and input for IMEC. With this statistics-based approach, the average RMSEs for the IMEC and IS methods were found to be 0.084 wt.% and 0.185 wt.%, respectively. Furthermore, the IMEC convergence graph indicated that the prediction RMSE quickly decreases to approximately 0.080 wt.% and stabilises within 40 iterations. The proposed IMEC method has important potential industrial-grade LIBS online quantitative analysis applications.