Fig 1.
The experimental materials and instruments.
(a) The photo of tellurium copper pellet, gold-plated red copper pin, gold-plated brass pin, and brass pin with gold-plating layer removed. The samples had been ablated by LIBS. (b) The schematic diagram of LIBS system.
Table 1.
The mass fraction of elements in three kinds of materials.
Table 2.
The spectral lines of Te and Zn extracted from the LIBS spectra acquired by monochromator and echelle grating spectrometer.
Fig 2.
The Te lines for LIBS parameter optimization.
Fig 3.
The SBR and RSD of Te lines under (a) laser pulse energy ranging from 50 to 90 mJ, and (b) delay time ranging from 1.0 to 3.0 μs.
Fig 4.
The mean LIBS spectra of Tellurium Copper, Brass and Red Copper acquired by (a) monochromator, and (b) echelle grating spectrometer.
Fig 5.
The PCA scatter plots of LIBS spectra acquired by (a) monochromator, and (b) echelle grating spectrometer.
Table 3.
The results of machine learning models based on extracted features for discrimination of three kinds of materials.
Fig 6.
The feature bands extracted by CARS, SPA algorithm and Te & Zn lines extracted based on NIST database from spectra acquired by (a) monochromator, and (b) echelle grating spectrometer.
Table 4.
The results of machine learning models based on full-spectra for discrimination of three kinds of materials.