NOVEL TEMPORAL FOURIER-TRANSFORM SPECKLE PATTERN SHEARING INTERFEROMETER

A method to measure the derivative of displacement using time variatio n changes in the object together with Fourier transform analysis in sp eckle shear interferometry is presented. The concept of the method is that the object is deformed continuously and a large number of sheared images of the object motion are acquired using a high speed CCD camer a. The derivative of the object deformation is then retrieved from thi s large set of data using Fourier transformation. The method is capabl e of obtaining information for object displacements over 500 mu m, whi ch is a very difficult task when using conventional electronic speckle pattern shearing interferometry. Theory as well as some of the experi mental results with the new method are delineated. (C) 1998 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(98)02406-4].