PHASE RECONSTRUCTION AND UNWRAPPING FROM HOLOGRAPHIC INTERFEROGRAMS OF PARTIALLY ABSORBENT PHASE OBJECTS

A method for automated phase reconstruction from holographic interfero grams of nonideal phase objects based on a two-dimensional Fourier tra nsform is described. In particular, the problem of phase unwrapping is solved because earlier techniques are inappropriate for the phase unw rapping from interferograms of partially absorbent objects. A noise-le vel-dependent criterion for the binary mask that defines the unwrappin g path for the flood algorithm is derived. The method shows high noise immunity, and the result is reliable provided that the true phase is free of discontinuities. The phase distribution in the outmasked regio ns is estimated by a linear least-squares fit to the surrounding unwra pped pixels.