Fig. 1. Schematic of laser cleaning monitoring system structure

Fig. 2. Morphological characteristics of material matrix carbon fiber and film epoxy resin

Fig. 3. Spectrometer collects reference LIBS of different materials. (a) Carbon fiber matrix; (b) film layer

Fig. 4. Movement track and diameter of laser spot. (a) Movement track; (b) diameter

Fig. 5. LIBS spectra of different single pulse energy densities. (a) 3.057 J/cm²; (b) 3.567 J/cm²; (c) 4.076 J/cm²; (d) 4.586 J/cm²

Fig. 6. LIBS of with different ablation times

Fig. 7. Spectra after mean smoothing and removing background under different times. (a) 1 time; (b) 2 times; (c) 3 times; (d) 4 times; (e) 5 times; (f) 6 times

Fig. 8. Peak values of Na atom changes under different ablation times at same location

Fig. 9. Correlation analysis results of matrix reference spectrum and 3^rd ablation spectrum collected

Fig. 10. Clustering results of DBSCAN algorithm. (a) Noise area division; (b) information-rich spectral data isolated point extraction

Fig. 11. Pearson correlation analysis results under different ablation times. (a) 1 time and 2 times; (b) 3 times and 4 times; (c) 5 times and 6 times

Fig. 12. Changing trend of Pearson coefficient under different laser ablation times

Fig. 13. Surface morphology of carbon fiber material after different times of ablation. (a) 1 time; (b) 2 times; (c) 3 times