Fig. 1. Measurement system for the bottom of a cavity. (a) Traditional system and (b) new system.

Fig. 2. Principle of the system structure.

Fig. 3. Principle of the system calibration.

Fig. 4. Calibration steps.

Fig. 5. Image of the fringe pattern.

Fig. 6. System structure.

Fig. 7. Experimental result. (a) The bottom shape of jar, (b) one of the fringe pattern images, (c) reconstruction result of the left part in Fig. 7(b), (d) reconstruction result of the right part in Fig. 7(b), and (e) stitching results of Figs. 7(c) and 7(d).

Fig. 8. Standard cube.

Fig. 9. Measurement of the standard plane.

Fig. 10. Standard ball.

Fig. 11. Measurement of the standard ball.