Fig. 1. Geometric model of deflectometric measurement. (a) Physical drawing; (b) schematic diagram

Fig. 2. Principle model of deflectometric surface measurement

Fig. 3. Reverse ray-tracing model^[20]

Fig. 4. Projection screen shift model^[17]

Fig. 5. Stereo deflectometry ^[21]

Fig. 6. Preknowledge model^[29]

Fig. 7. Calibration method of flat mirror with markers ^[33]

Fig. 8. Experimental results of measured surface ^[35]. (a) Measurement result of ZYGO interferometer; (b) measurement result based on three-coordinate calibration; (c) measurement result after first-step correction; (d) measurement result after second-step correction; (e) residual error between measurement result after first-step correction and measurement result based on three-coordinate calibration; (f) residual error between measurement result after second-step correction and measurement result based on three-coordinate calibration

Fig. 9. Layout of on-axis geometry with beam splitter^[38]

Fig. 10. Models of regional reconstruction method

Fig. 11. Architecture of D-UNet^[54]

Fig. 12. Photo of experimental measurement with infinite deflectometric system^[58]. (a) Tested convex spherical optic with 50-mm diameter aperture; (b) interferogram acquired with Zygo interferometer; (c) photo of infinite deflectometric system

Fig. 13. Computer-aided deflectometric system for reflective convex surface measurement^[35]

Fig. 14. Annular steps^[69]. (a) Photo of steps; (b) fringe pattern reflected by steps

Fig. 15. Measurement result of stained glass surface^[70]

Fig. 16. Computer-aided deflectometric system for transmitted multisurface measurement^[77]

Fig. 17. Reconstruction results of front and rear surfaces of freeform refractive lens^[77]

Fig. 18. Experimental setup for microscopic deflectometric system^[78]

Fig. 19. Schematic diagram of off-axis deflectometric microscope system^[80]

Fig. 20. Comparison between measurement results obtained by off-axis deflectometric microscope system and Wyko profilometer^[80]. (a) Surface roughness measured by off-axis deflectometric microscope system; (b) surface roughness measured by Wyko profilometer; (c) line profile comparison in x direction; (d) line profile comparison in y direction

Fig. 21. Schematic diagram of on-axis deflectometric microscope system^[39]

Fig. 22. Flow chart of fringe decoding in instantaneous deflectometry^[80-81]

Fig. 23. Fringe coding process in instantaneous deflectometry based on frequency carrier^[86]