Squeezing Interferometry for Optical Phase Extraction in Digital Speckle Pattern Interferometry

The purpose of the present work is the use of squeezing interferometry Technique to provide an optical phase mapping from DSPI fringes. The main advantage of this technique is to demodulate by means of a quadrature Gabor filter, a single carrier-frequency fringe pattern formed from intermixing M shifted fringe patterns that are synthetised numerically by the combination of a primary interferogram and its quadrature, which leads directly to the phase without any speckle denoising algorithm, and this after unwrapping the phase with a standard phase unwrapping algorithm and using a simple median filter to smooth the result. This approach was tested on simulated interferograms for different speckle sizes and fringes densities; it was found that the procedure was able to give the result with a good accuracy for all these cases. An application of the proposed procedure to retrieve the phase for experimental fringes recorded from the thermomechanical study of the MOS power transistor is also presented.