Fig. 1. Schematic diagram of phase measurement deflectometry

Fig. 2. Surface reflection and refraction

Fig. 3. Refraction and reflection superposition

Fig. 4. Iterative flow chart

Fig. 5. Schematic diagram of gradient calibration

Fig. 6. Parasitic reflection of fringe. (a) Horizontal fringe; (b) Vertical fringe

Fig. 7. Wrapped phase optimization. (a) Before optimization; (b) After optimization

Fig. 8. Comparison between phase and true value. (a) Initial phase; (b) First iteration; (c) Second iteration; (d) Third iteration

Fig. 9. The difference between the phase calculation result and the true value. (a) The upper surface phase; (b) Phase difference of the upper surface; (c) Lower surface phase; (d) Phase difference of the lower surface

Fig. 10. Hardware system structure diagram

Fig. 11. (a) Transparent glass plate; (b) Parasitic reflection of horizontal fringe; (c) Parasitic reflection of vertical fringe

Fig. 12. Transparent glass plate phase. (a) Horizontal fringes on the upper surface; (b) Horizontal fringes on the lower surface; (c) Horizontal fringe unwrapped phase; (d) Vertical fringes on the upper surface; (e) Vertical fringes on the lower surface; (f) Vertical fringe unwrapped phase

Fig. 13. Comparison of solution methods. (a) Comparison of initial values of the upper surface; (b) Comparison of initial values of the lower surface; (c) Multi-frequency phase-shifting method on the upper surface; (d) Multi-frequency phase shifting method lower surface; (e) Multi-frequency method upper surface; (f) Multi-frequency method lower surface

Fig. 14. Surface gradient of transparent glass panels. (a) x direction of the upper surface; (b) ydirection of the upper surface; (c) x direction of the lower surface; (d) y direction of the lower surface

Fig. 15. Three-dimensional morphology of upper and lower surfaces of transparent glass plate. (a) Upper surface morphology; (b) Lower surface morphology

Fig. 16. Measurement results of glass plate with different thickness. (a) 6 mm; (b) 6 mm cross-sectional; (c) 12 mm; (d) 12 mm cross-sectional

Fig. 17. (a) Plano-convex lens; (b) Parasitic reflection of horizontal fringe; (c) Parasitic reflection of vertical fringe

Fig. 18. Calculation and comparison of lens phase. (a) Horizontal fringes on the upper surface; (b) Horizontal fringes on the lower surface; (c) Vertical fringes on the upper surface; (d) Vertical fringes on the lower surface

Fig. 19. Three-dimensional morphology of plano-convex lens