Misfocused Speckle Shearing Moire.
MILITARY ACADEMY WEST POINT N Y DEPT OF MECHANICS
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The development of speckle photography is briefly discussed. The technique and theory of misfocused speckle shearing Moire is examined. A single laser beam is used to illuminate a specimen which is then photographed by a misfocused camera through two laterally separated apertures. The optical phase shift of the recorded speckle grid and the mechanical shift of the speckle is discussed, and an explanation of the combination of the two effects which yields hybrid displacement and strain fringes is presented. Photographs of the fringes on the specimen are compared with plots for the theoretical fringes for four examples to substantiate the theory. Author