Comparative study of fringes generation in two-spacing phase-shifting profilometry

A two-spacing phase-shifting techniques for three-dimensional shape measurement based on digital fringe projection is presented. Combination of phase-shifting method with computer generated fringe patterns with a sinusoidal intensity profile allows precise measurement in real time operating mode. The two-spacing technique allows absolute coordinate estimation of the investigated specimen. The theoretical background, experimental results as well as comparison with traditional laser phase-shifting interferometry are discussed. The obtained outcomes successfully display the applicability of this technique for surface profile measurement. The proposed technique is especially useful for remote, non-destructive in-situ inspection of real objects.