Fig. 1. Schematic of experimental setup

Fig. 2. Peak intensity calculated with cubic spline interpolation

Fig. 3. (a) Line graph and (b) histogram plot of laser energy

Fig. 4. (a) Line graph and (b) histogram plot of background signal of spectrometer

Fig. 5. (a) Line graph and (b) histogram plot of intensity f H atomic 656.30 nm spectral line

Fig. 6. Relationship between RSD and average pulse number

Fig. 7. Relationship between average spectral intensity of 50 pulses and order number

Fig. 8. Diagram of laser-matter interaction at different positions

Fig. 9. Diagram of laser-matter interaction under different pulses

Fig. 10. (a) Line graph and (b) histogram plot of intensity of Mg atomic spectral line at different sample positions

Fig. 11. Surface images of laser ablation crater after 1000 pulses at different sample positions. (a) 0 mm; (b) 3 mm; (c) 6 mm; (d) 9 mm; (e) 12 mm; (f) 15 mm

Fig. 12. Marginal histogram of spectral intensity of two repeated experiments at position of 12 mm

Fig. 13. Relationship between average spectral intensity of 50 pulses and order number. (a) Sampling point 1; (b) sampling point 2