We propose a new method for measuring large-object deformations byusing temporal evolution of the speckles in speckleinterferometry. The principle of the method is that by deformingthe object continuously, one obtains fluctuations in the intensity ofthe speckle. A large number of frames of the object motion arecollected to be analyzed later. The phase data for whole-objectdeformation are then retrieved by inverse Fourier transformation of afiltered spectrum obtained by Fourier transformation of thesignal. With this method one is capable of measuring deformationsof more than 100 mum, which is not possible using conventionalelectronic speckle pattern interferometry. We discuss theunderlying principle of the method and the results of theexperiments. Some nondestructive testing results are alsopresented.
We outline a novel method for determining the shape of an object by use of temporal Fourier-transform analysis in dual-beam illumination speckle interferometry. The object whose shape is to be determined is rotated about an axis, and a number of frames of the image of the object motion are acquired. Temporal in-plane displacement that is due to the object rotation is related to the shape of the object and is retrieved from this large set of data by Fourier transformation. With this method one can determine the absolute height of the object with variable resolution, thereby allowing shapes of objects with large and small slopes to be determined. The theory of the method along with experimental results is presented.
A method to measure derivatives of displacement using time variation changes in the object together with Fouriertransform analysis in speckle shear interferometry is aimed in this paper. The concept of the method is that the object is deformed continuously and a number of sheared images of the object motion are acquired using a high speed CCD camera. The derivative of the object deformation is then retrieved from this large set of data using Fourier-transformation. The method is capable of obtaining information for object displacements over 1000 microns a very difficult task when using conventional electronic speckle pattern shearing interferometry. Theory as well as some of the experimental results with the new method is delineated in this paper.
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