A phase unwrapping method using the error-controlled fringe projection scheme for phase-shifting projected fringe profilometry is presented. Most unwrapping methods cannot cope with the problems caused by low signal-to-noise ratios. The presenting method can detect such kind of errors and recover the mistake.
A pulsed-encoding scheme for phase-shifting projected fringe profilometry is presented. The projected fringe patterns used to perform the phase-shifting technique can be used to identify the fringe orders directly. For the filed of view 300mm×300mm, systematic accuracy was approximately 600μm.
A contrast-encoded method based on the phase-shifting technique for 3D shape measurements is presented. Phase extraction is performed by the phase-shifting technique, while unwrapping is discerned by the quaternary contrastencoded patterns. There is no need to take additional projections for phase unwrapping. The fringe patterns used for phase extraction can be analyzed for unwrapping directly. This makes it more efficient to perform high speed, real time, and low cost 3-D shape measurements.
A full-field method using fringe patterns to identify the profile of a specular surface is presented. A virtual image of the fringe pattern is formed by the specular surface. The specular surface deforms the image of fringe pattern. Thus, phase of the deformed fringes can be utilized to retrieve the profile of the inspected surface.
A one-shot technique for profile measurements is presented. A two-dimensional deinge-encoded pattern is used to illuminate the inspected object and a monochromatic camera is employed to observe the deformed fringes at another view angle. The 2D fringe-encoded pattern provides additional information to identify the fringe order. Even though the surface color or reflectivity varies rapidly with positions, it distinguishes the fringe order very well.
A fringe projection profilometry is presented. It uses the phase-shifting technique perform the phase-extraction and use the ternary-encoded patterns to identify the fringe orders. Only five-shot measurements are required for data processing. Experiments show that absolute phases could be obtained with high reliability.
A one-shot profilometry for surfaces with color or reflectivity discontinuties is presented. It uses binary-encoded pattern to illuminate the inspected object and a monochromatic camera to observe the deformed fringes at another view angle. The encoded pattern provides additional to identify the fringe order. For spatially isolated objects or surfaces with large depth discontinuities, unwrapping can be identified without ambiguity. Even though the surface color or reflectivity varies rapidly with position, it distinguishes the fringe order as well.
A phase unwrapping method by spatially encoding the fringe patterns is presented for phase-shifting projected fringe
profilometry. For spatially isolated objects or surfaces with large depth discontinuities, unwrapping can be identified
without ambiguity. Even though the surface color or reflectivity varies rapidly with position, it distinguishes the fringe
order accurately.
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