<title>Improved digital speckle correlation method and its application in copper thin film</title>

Abstract

The digital speckle correlation method (DSCM) is a rapidly developing technique of photomechanics. It has been used to measure the surface deformation for its advantages of non- contact, real time, whole field and direct measurement. In this paper, an algorithm is proposed by introducing optimization theory into DSCM. In the improved DSCM, the 1D search determines the step size of iteration, and the inverse matrix of second- order derivative matrix of correlation function is calculated by the quasi-Newton method. By the improvement, the computational; workload is reduced and the convergence velocity is improved. This paper also illustrates the application of digital speckle correlation method in experimental fracture analysis of copper film. Experimental results show that the improved DSCM is an efficacious test techniques in studying the fracture behavior of thin film materials.