Abstract
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 de- noising 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.
Highlights
Digital speckle pattern interferometry (DSPI) is a whole field optical method for non- contact and nondestructive surface analysis
As DSPI fringes are characterized by a strong speckle noise background, a denoising method[4,5,6] must be used before the phase evaluation
We propose to combine numerically the interferogram
Summary
Digital speckle pattern interferometry (DSPI) is a whole field optical method for non- contact and nondestructive surface analysis. It’s considered as a powerful tool for industrial measurements. It enables full-field measurement of optical phase changes via the acquisition of speckle patterns[1,2,3]. A simple subtraction is usually performed to obtain a correlation fringe pattern. The greatest challenges in speckle interferometry focus on relating fringe patterns to phase mapping, permitting the direct determination of surface deformation. As DSPI fringes are characterized by a strong speckle noise background, a denoising method[4,5,6] must be used before the phase evaluation. The development of more sophisticated phase evaluation algorithms such as Phase Shifting methods, are continuously needed[7,8,9]
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