Full-field phase error analysis and compensation for nonsinusoidal waveforms in phase shifting profilometry with projector defocusing

Phase shifting profilometry (PSP) using binary fringe patterns with projector defocusing is widely used for high-speed three-dimensional (3D) shape measurement. In this technique, the projector projects binary fringe patterns instead of the sinusoidal fringe patterns to perform 3D shape measurement. However, inappropriate defocusing degree of the projector causes the captured fringe patterns to be nonsinusoidal waveforms or remaining binary structure, which results in phase error and therefore measurement error. In this paper, a novel method was proposed not only to measure the phase error directly but also to extract the full-field phase error distribution in a large depth range of projector defocusing. Then a mathematical phase error function in terms of the depth z was established. Finally, with help of the detected phase error distribution, the phase error function was calibrated and used to compensate the phase error at arbitrary depth ranges within the calibration volume. The experimental results demonstrated that the proposed method can detect full-field phase error distribution successfully, and improve the phase accuracy significantly.