Abstract
Multi-wavelength digital-phase-shifting moiré was demonstrated using multiple moiré 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 moiré wavelength calibration determines a moiré-wavelength to height relationship that permits pixelwise refinement of the moiré 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 moiré 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.
Highlights
Fringe projection profilometry (FPP) [1] is commonly used for full-field non-contact surface-shape measurement for a wide range of applications
In spatial phase unwrapping [5,6], phase unwrapping at each pixel is computed based on phase values at adjacent pixels; phase errors can occur at surfaces with geometric discontinuities or spatially isolated surfaces [7], and the error can propagate across pixels
This paper combines heterodyne multi-wavelength temporal phase unwrapping and digital moiré in a new method of multi-wavelength digital-phase-shifting moiré based on moiré wavelength
Summary
Fringe projection profilometry (FPP) [1] is commonly used for full-field non-contact surface-shape measurement for a wide range of applications. Phase-shifting profilometry (PSP) [2] has been commonly used because of its high accuracy, high spatial resolution, and low sensitivity to variations of background intensity and surface reflectivity [2,3]. In PSP, typically three or four phase-shifted sinusoidal patterns are projected onto a surface and camera captured images of the deformed patterns are used to compute a phase map, which contains surface-height information. In spatial phase unwrapping [5,6], phase unwrapping at each pixel is computed based on phase values at adjacent pixels; phase errors can occur at surfaces with geometric discontinuities or spatially isolated surfaces [7], and the error can propagate across pixels. Multiple wrapped phase maps of different fringe frequencies or wavelengths are required.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
