A multiple wavelength unwrapping algorithm for digital fringe profilometry based on spatial shift estimation

In this paper, a new approach is presented for solving the problem of spatial shift wrapping associated with Spatial Shift Estimation (SSE)-based Fringe Pattern Profilometry (FPP). The problem arises as the result of fringe reuse (that is, fringes periodic light intensity variance), and the spatial shift can only be identified without ambiguity with the range of a fringe width. It is demonstrated that the problem is similar to the phase unwrapping problem associated with the phase detection based FPP, and the proposed method is inspired by the existing ideas of using multiple images with different wavelengths proposed for phase unwrapping. The effectiveness of the proposed method is verified by experimental results on an object with complex surface shape. 2014 SPIE.