Phase measurement in digital speckle pattern interferometry using wavelet transforms: recent developments

This presentation reviews recent developments carried out by the authors to evaluate phase distributions in digital speckle pattern interferometry (DSPI) using wavelet analysis. The advantage of this approach is that it requires only one interferogram to be analyzed and does not need the application of a phase unwrapping algorithm neither the introduction of carrier fringes in the interferometer. In particular, it is presented an approach that takes into account the second order contribution of the phase map. It is also presented the application of a smoothed time-frequency distribution which improves the accuracy of the results obtained in the neighborhood of stationary phase points and also when the generated DSPI fringes present discontinuities in the first derivative of the phase map.