Comparison Of Digital Speckle Correlation Algorithm And Its Dual Microscope

Displacement and strain measurement are an important task of mechanical testing. The digital speckle correlation method (DSCM) is an accurate method of measuring displacement field by using computer aid test. Through calculating the variable process of the correlative coefficient along with displacement and strain between two speckle field images gathered before and after movement or distortion of the object, the basic theory of DSCM is to find out the displacement and strain corresponding to the maximum of correlative coefficient which is the displacement and strain corresponding to the fact.In this paper, the state of the technique is reviewed and illustrated by reference to recent publications on the developments and application of DSCM. Then the theory of DSCM and the excellence of the simulative speckle images are introduced, and the way to create the simulative speckle images is described in this paper.The currently most often used algorithms for subpixel registration can be divided into three categories: the correlation coefficient interpolation method, the correlation coefficient distribution based on fitting method, and gradient-based algorithm which is comprised of the gradient-based algorithm based on image and the gradient-based algorithm based on analogous function. They are introduced in this paper and programmed by Matlab. Based on simulated speckle images, the optimal method is verified through the comparison.In succession, this paper describes a high accuracy microscopic deformation measurement system, which is combined with the digital speckle correlation technique and the micrology. The mechanical properties of the polymethyl methacrylate are measured in the experiments. The accuracy of the algorithm which is used in the system is validated. And measuring results have been analyzed in detail. The results are compared to electromotive results.