Spatiotemporal phase unwrapping and its application in fringe projection fiber optic phase-shifting profilometry

Abstract

A spatiotemporal phase unwrapping method is proposed that combines the dynamic optic fiber interferometric fringe projection method and the phase-shifting technique. A fringe projection fiber optic phase- shifting interferometer was set up, in which the fringe spacing and rotation can be easily adjusted. In the first step of the spatiotemporal phase unwrapping method, a large effective wavelength can be chosen so that the phase jump at the discontinuous profile is less than ?, then the spatial phase unwrapping method can be applied. Several intermediate phase maps can be obtained by changing fringe pitch and fringe orientation, reducing the effective wavelength step by step, and unwrapping each pixel along the time axis. In the final step, a high precision result can be obtained. A minimum number of steps can be chosen to obtain the required accuracy according to the conclusion presented. An experimental result is presented for the measurement of a discontinuous object and shows the validity of the proposed method.