Fig. 1. Configuration of surface defect detection system

Fig. 2. Optical paths of incident light under influence of double surfaces

Fig. 3. Primary reflection light path

Fig. 4. Secondary reflection light path

Fig. 5. Experimental setup

Fig. 6. Defect detection results for front surface. (a) Detection result of UIT; (b) detection result of SIT; (c) phase distribution of front surface obtained by ECA; (d) phase distribution of front surface obtained by SMM; (e) detection result of proposed method; (f) comparison of cross-sections among different methods

Fig. 7. Local comparison of detection results among different methods

Fig. 8. Result comparison between SIT and proposed method. (a) Grayscale distributions corresponding to Figs. 6(b) and 6(e);(b) binarization result corresponding to Fig. 6(b); (c) binarization result corresponding to Fig. 6(e)

Fig. 9. Comparison between single surface detection methods and proposed method. (a) Detection result of UIT; (b) detection result of SIT; (c) detection result of front surface obtained by proposed method; (d) detection result of back surface obtained by proposed method; (e) comparison of cross-sections among different methods

Fig. 10. Comparison between double surface detection methods and proposed method. (a) Phase distributions of front and back surfaces obtained by ECA; (b) phase distributions of front and back surfaces obtained by SMM; (c) detection results of front and back surfaces obtained by proposed method; (d) comparison of cross-sections among different methods