Double-pulsed carrier speckle-shearing pattern interferometry for transient deformation analysis

We report on a novel technique for the evaluation of transient phase in double-pulsed electronic speckle-shearing pattern interferometry. Our technique requires the acquisition of just two speckle-shear interferograms (one before and one after object's deformation) which are correlated by subtraction to obtain a fringe pattern. A spatial carrier is generated by means of an original optical setup based on the separation and later recombination of the two beams produced by a Nd:YAG twin pulsed laser. One introduces an optical path difference in the curvature radii of the illumination beams by mismatching the distances from two diverging lenses to a beam combiner. This procedure gives rise to a linear phase term in the second speckle-shear interferogram that plays the role of a spatial carrier and allows the use of spatial phase measurement methods to analyze the fringe pattern. We present the theoretical aspects of the technique as well as its experimental implementation.