Phase measurement algorithm without phase-unwrapping problem for phase-stepping interferometry

A new phase measurement algorithm without phase-wrapping problem was presented. It is mainly used in the interferograms of few and straight fringes with noise and corrupted regions. It is based on a seeding pixels method. It first searches N seeding pixels in terms of the good modulation. The interferograms are then segmented into N parts by the seeding pixels. The adjacent seeding pixels phase difference is constrained to be in the range from -πto +π. Since the phase measurement is relative, if one of the seeding pixels phases is a constant, other seeding pixels phases can be easily obtained by the phase-stepping algorithm. Moreover, phases of other pixels in the interferogram can be determined through a simple operation with the seeding pixels. A smooth flat mirror was tested in a Linnik interference microscope with phase-stepping algorithm. The interferograms were corrupted with many dirty spots or regions. The experimental results show that this new algorithm is fast and robust.