Two-dimensional discrete wavelets transform for optical phase gradient extraction in interferometry shearing

In this paper, we present a method for phase gradient evaluation based on two-dimensional discrete wavelets transform decomposition in digital speckle shearing interferometry. From only fringe shearing and using a simple median filter to smooth the fringe, the phase gradient distribution is extracted by the ratio between detail and approximation. Modulation process is realized digitally by combining a computer generated greeting with two shifted fringe pattern. We propose to use only single fringe and generate its quadrature by spiral phase transform SPT. Then, we apply the 2D-DWT algorithm on modulated fringe shearing, phase gradient computed by a standard phase unwrapping algorithm with a good accuracy and we show by image quality index a good performance