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

Abstract

Phase unwrapping is one of the most important procedures in three-dimensional phase measurement profilometry and has attracted great research interest in the past few decades. However, existing phase unwrapping methods require additional patterns or pre-assumptions 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 algorithm that retrieves the absolute phase without external information or priors. To this end, we firstly embed a novel space-varying phase shift that uniquely determines the fringe order information into sinusoidal patterns, and then extract it to retrieve the absolute phase by pixel-wise 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 theoretical, simulation and extensive experimental results demonstrate its superiority in fast and accurate 3D shape measurement.