Holographic deformation measurements by Fourier transform technique with automatic phase unwrapping

A carrier fringe technique for measuring surface deformation is described and verified by experiments. In contrast to conventional holography and fringe analysis, this holographic system is based on fiber optics and automatic spatial carrier fringe pattern analysis techniques. Single-mode optical fibers are used to transfer both the object and reference beams. Carrier fringes are generated by simply translating the object beam between two exposures. The fast Fourier transform method is used to process the interferograms. The experiment gives an example of the tile-level minimum spanning tree phase unwrapping technique and introduces a new pixel-level noise immune unwrapping strategy also based on minimum spanning trees. The test object is a centrally loaded disk. An excellent correlation between the theoretical deformation profile and that suggested by the technique is given.