Self-Unwrapping Phase-Shifting for Fast and Accurate 3-D Shape Measurement

Phase unwrapping is one of the most important procedures in 3-D phase measurement profilometry (PMP) and has attracted great research interest in the past few decades. However, the existing phase unwrapping methods require additional patterns or preassumptions to determine the fringe orders for further absolute phase retrieval, which dramatically affect the measurement efficiency. To address this problem, we propose a generic self-unwrapping phase-shifting (SUPS) algorithm that retrieves the absolute phase without external information or priors. To this end, we first embed a novel space-varying phase shift (SPS) that uniquely determines the fringe order information into sinusoidal patterns, and then extract it to retrieve the absolute phase by pixelwise calculation. Our method achieves higher efficiency over previous methods while preserving the measurement precision, and the minimum number of patterns required is only four. All the theoretical, simulation, and extensive experimental results demonstrate its superiority in fast and accurate 3-D shape measurement.

Automated summary

Phase unwrapping is a crucial step in 3-D phase measurement. Existing methods require additional information or assumptions, which affect measurement efficiency. To address this, we propose a self-unwrapping phase-shifting algorithm that retrieves absolute phase without external information, achieving higher efficiency and accuracy.