Absolute phase retrieval method based on De Bruijn sequence and phase coding

Existing methods of the phase unwrapping method require additional fringe patterns to determine the fringe order. This process has a significant impact on the measurement speed. To address this problem, we proposed a self-encoded phase shift method based on segmented phase coding. A De Bruijn sequence code of arbitrary order is embedded into the sinusoidal fringe and introduced a set of phase coding expanded codewords. We obtain information on fringe order by a set of phase-shift sinusoidal fringes while extracting the unwrapped phase and combine the information of the fringe order in the phase coding to get the complete fringe order. The proposed method does not require any priori information, and only six fringe patterns need to be projected to complete the workload of the traditional segmented phase coding, which saves the projection time of a set of patterns. The experimental results confirm the feasibility of the proposed method and demonstrate its ability to measure complex isolated objects with a maximum root mean square error of 0.059 mm.