Fig. 1. Experimental setup of laser-induced breakdown spectroscopy

Fig. 2. Stainless steel sample

Fig. 3. Effects of different parameters on signal intensity, relative standard deviation, and signal-to-background ratio. (a)-(c) Effects of laser energy; (d)-(f) effects of delay time; (g)-(i) effects of focus depth

Fig. 4. Original spectrum and spectrum after pretreatment of 304 stainless steel. (a) Original spectrum; (b) spectrum after preprocessing

Fig. 5. Classification model establishment and test flow chart

Fig. 6. Influence of decision tree number on classification accuracy

Fig. 7. Classification accuracy of 100 experiments