Laser Speckle Interferometer for Deformation Measurement based on Fast Fourier Transform method

Abstract

In this paper, Laser speckle image processing based on Fast Fourier Transform method for displacement measurement is presented. Capturing Laser speckle images before displacement and after displacement of the specimen is the technique involved in this measurement. The cross correlation is computed by two 2Dimensional Fast Fourier Transforms (one direct and the other is inverse) and a complex multiplication. This is a non-contact, flexible measurement with high accuracy and simple operation. The results are verified by conventional gauge methods.