Grid fringe pattern Fourier transform profilometry

In order to increase measurement precision and overcome discontinuous phase unwrapping in the 3-D shape measurement of discontinuous objects, an improved Fourier transform profilometry(FTP) was presented with a grid fringe pattern as spatial carrier-fringes. Two 1-D deformed grating patterns were extracted from the deformed grid fringe pattern using 2-D Fourier transform and fixed bandwidth filters. Two wrapped phases were obtained from these both one-dimension deformed patterns, respectively, and the corresponding unwrapped phases were achieved by means of a lookup table method. The experimental results show that the technique can overcome the low measurement precision using 1-D single frequency fringe pattern, the possible frequency overlaps using 1-D dual-frequency fringe pattern and tolerate the height discontinuity of the 3-D shape measurement; the above method is available.