MODULATION ANALYSIS OF PHASE-SHIFTED HOLOGRAPHIC INTERFEROGRAMS

A new evaluation technique for phase-shifted holographic interferograms is developed and verified by experiments. In evaluating the interferograms, both the discrete phase distribution and the intensity modulation of interference fringes are calculated and a binary control mask is generated by analysing histograms and tracing local minima of the intensity modulation distribution. The control mask is used to identify valid and invalid areas of the discrete phase distribution in subsequent phase unwrapping and phase interpolation, and to control the path of phase unwrapping. The evaluation of experimentally obtained phase-shifted holographic interferograms shows that this method can be successfully applied for the processing of complex interference patterns, even if the interferograms have fringe discontinuities and shaded areas.