Absolute measurement of surface profiles in phase-shifting projected fringe profilometry

Phase-shifting projected fringe profilometry (PSPFP) is a powerful tool in the profile inspection of a large variety of rough surfaces. In many applications, absolute PSPFP measurements, capable of compensating for the lateral distortions in the measured object shape and providing an expression of the measured shape under a predefined reference system, are highly desired. In this paper, an absolute PSPFP technique combining the lateral calibration and the phase-to-depth calibration is proposed. The principles of the proposed absolute PSPFP measurement technique will be discussed together with the calibration and measurement methods based on a particular formalism of absolute PSPFP measurements.