Deformation Measurement Using Dual-Frequency Projection Grating Phase-Shift Profilometry
2π phase ambiguity problem is very important in phase measurement when a deformed object has a large out of plane displacement. The dual-frequency projection grating phase-shifting profilometry (PSP) can be used to solve such an issue. In the measurement, two proper-chosen frequency gratings are utilized to synthesize an equivalent wavelength grating which ensures the computed phase in a principal phase range. Thus, the error caused by the phase unwrapping process with the conventional phase reconstruct algorithm can be eliminated. Finally, experimental result of a specimen with large plastic deformation is given to prove that the proposed method is effective to handle the phase discontinuity.
Key wordsdual-frequency phase-shift profilometry projection grating phase unwrapping deformation
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