A novel 2+1 three-dimensional measurement for temporal phase unwrapping

A novel 2+1 three-dimensional (3D) measurement for temporal phase unwrapping is proposed. While two high-frequency complimentary sinusoidal fringes and one low-frequency sinusoidal fringe are projected onto the measured object respectively, the corresponding deformed patterns can be captured. Then the high-frequency wrapped phase can be extracted from the two high-frequency complimentary deformed patterns by high-accuracy computer-generated moiré profilometry (HCGMP). Due to its shared direct current (DC) component with the high-frequency deformed pattern, the low-frequency wrapped phase can still be extracted from the only one low-frequency deformed pattern by HCGMP. Because the extracted wrapped phase excludes the phase contribution of the reference plane, a sufficiently high low-frequency fringe projection can also make the low-frequency wrapped phase become its continuous phase without phase unwrapping. And then, the high-frequency wrapped phase is unwrapped, guided by the low-frequency unwrapped phase. Finally, the 3D profile of the measured object can be reconstructed successfully. Compared to the conventional 2+1 algorithm, the proposed algorithm can accomplish temporal phase unwrapping and improve the 3D measuring accuracy. It has a good application prospect in real-time 3D measurement. The experiment results show the feasibility and effectiveness of the proposed algorithm.