A flexible phase-shifting method with absolute phase marker retrieval

The phase-shifting algorithm is an important and widely employed technology in optical 3D shape measurement. An additional absolute phase marker map is necessary to acquire the absolute phase with traditional phase-shifting algorithm, which not only has a low efficiency but also may not meet certain special requirements of the practical application. In this study, a flexible phase-shifting method, which does not need the additional absolute phase marker map, was developed. A newly designed absolute phase marker was embedded into one of the phase fringe images, and this was retrieved according to its mathematical model; then, the primary phase inside and outside the absolute phase marker region was computed with different methods. Results of experiments show that the retrieval of the marker is easy and flexible, and the phase computation with this novel method is accurate and robust.