Shape Measurement by use of Temporal Fourier transformation in Dual-Beam Illumination Speckle Interferometry.

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.