Two error sources in grating projection profilometry: analysis and compensation

In this paper is introduced a new concept - image point displacement (IPD), on the basis of which the principles and key tasks of light pattern projection profilometry are re-interpreted and evaluated. Two error sources that have not been addressed adequately are analyzed in detail. One is coordinate deviation, which comes from the different magnification at different depth. The other is the nonlinearity of the phase-IPD and phase-height relationship. These error sources will be more and more non-negligible as researchers make their ways to improve accuracy and increase measuring range. Some compensation approaches are also proposed, which have been verified by numerical simulations and experiments.