Derivatives of displacement obtained by direct manipulation of phase-shifted interferograms

An anisotropic evolution formulation applied in 2-D unwrapping of discontinuous phase surfaces

In this paper, a new method to reconstruct piecewise continuous phase estimates using inphase and quadrature components acquired from interferometry measurements is derived and discussed. The method, based on the concept of anisotropic evolution formulations, is shown to be far less noise sensitive than similar methods operating on modulo-mapped data (i.e., traditional phase unwrapping methods). The method is able to produce reliable phase estimates from data containing complex sheared structures in combination with high noise content without relying on user-defined weights.

Noise-immune method for locating wrap regions in phase-step interferometry

A method is presented that can be applied to phase-step interferometry to locate the regions within which integral multiples of pi should be added to the wrapped phase that results from arctangent calculations. Unlike previous methods, this one is immune to the noise-related errors that confuse simple phase-unwrap schemes. It makes use of the fact that the noise-related errors occur at fixed locations in the phase map, whereas the location of the wrap regions depends on the way in which the arctangent is calculated.