Multi-Wavelength Digital-Phase-Shifting Moire Based on Moire Wavelength

Featured Application The multi-wavelength digital-phase-shifting moire based on moire wavelength permits 3D shape measurement of surfaces with geometric discontinuities and multiple spatially-isolated surfaces, using only two or three captured images. This is advantageous in the image data acquisition process to enable fast measurement of dynamic surfaces, either moving or deforming. Abstract Multi-wavelength digital-phase-shifting moire was demonstrated using multiple moire wavelengths determined by system calibration over the full working depth. The method uses the extended noisy phase map as a reference to unwrap the phase map with a shorter wavelength, and thus achieve a less noisy and more accurate continuous phase map. The moire wavelength calibration determines a moire-wavelength to height relationship that permits pixelwise refinement of the moire wavelength and height during 3D reconstruction. Only a single pattern has to be projected and, thus, a single image captured to compute each phase map with a different wavelength to perform digital-phase-shifting moire temporal phase unwrapping. Only two captured images are required for two-wavelength phase unwrapping and three captured images for three-wavelength phase unwrapping. The method has been demonstrated in the 3D surface-shape measurement of an object with surface discontinuities and spatially isolated objects.