Fig. 1. Spot diameter corresponding to different ablation power. (a) Ablated sequence spots; (b) relationship curve

Fig. 2. Spot images processed by different methods. (a) Original image; (b) grayscale transformation method; (c) histogram equalization method; (d) PCA method

Fig. 3. Pseudo-color image and its graying. (a) Pseudo-color image; (b) grayscale image

Fig. 4. L component. (a) L component of original image; (b) L component after mask processing

Fig. 5. Average gray curves of L component of original spot image and spot image after mask processing. (a) Original spot image; (b) spot image after mask processing

Fig. 6. Average gray characteristic curve of sample

Fig. 7. Average gray characteristic curves before and after fractal interpolation. (a) Before fractal interpolation; (b) after fractal interpolation

Fig. 8. Average gray characteristic curves obtained by combining fractal interpolation with wavelet transformation. (a) With fractal interpolation; (b) combing fractal interpolation with wavelet transformation

Fig. 9. Average gray characteristic curves before and after wavelet transformation. (a) Before wavelet transformation; (b) after wavelet transformation

Fig. 10. Laser ablation experiment of monocrystalline silicon

Fig. 11. Average gray characteristic curve of spot images under different power

Fig. 12. Correlation curve of grayscale and power

Fig. 13. Average gray characteristic curve in a cycle of processing