Study on wavelet transform profilometry based on fringe projection with two carrier frequencies

We focus on the discussion of Wavelet transform profilometry based on dual-frequency fringe projection in this work. Employing a deformed fringe pattern with dual-frequency components captured by a CCD camera, we can calculate two wavelet ridge-lines from its continuous wavelet transform coefficients. Then, two sets of wrapped phase maps with difference resolution can be extracted. The longer the equivalent wave length is, the lower the measurement accuracy is. However, the direct shape reconstruction is not accuracy from low frequency component even though the fringe order from the low frequency component is easier to obtain correctly than from the high frequency component. Therefore the fringe order from low frequency component is used to guide the calculation of the fringe order of the high frequency component in dual-frequency fringe projection technique. Employing the relationship between the two carriers f2 and f1 (supposing f1<f2). we discuss the structure condition and sampling condition of wavelet transform profilometry based on dual-frequency fringe projection from the aspect of frequency analysis, which guarantee the correct shape reconstruction from the dual-frequency fringe. We finished the theoretical derivation and computer simulations to verify the correction of the theory.