Application of an improved subpixel registration algorithm on digital speckle correlation measurement

• Published in: Optics and laser technology 2003-10, Vol.35 (7), p.533-542
• Main Authors: Zhang, Jun, Jin, Guanchang, Ma, Shaopeng, Meng, Libo
• Format: Article
• Language: English
• Subjects: Digital speckle correlation method (DSCM); Exact sciences and technology; Fundamental areas of phenomenology (including applications); Gradient-based algorithm; Imaging and optical processing; Measurements common to several branches of physics and astronomy; Metrology, measurements and laboratory procedures; Optics; Physics; Spatial dimensions (e.g.: position, lengths, volume, angles, displacements, including nanometer-scale displacements); Spatial dimensions (eg, position, lengths, volume, angles, displacements, including nanometer-scale displacements); Speckle and moire patterns; Subpixel registration
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/S0030-3992(03)00069-0

Digital speckle correlation method (DSCM) has been widely used in experimental mechanics to obtain the surface deformation fields. One of the challenges in practical applications is how to obtain the high accuracy with far less computation complexity. To determine the subpixel registration of the DSCM, a high efficient gradient-based algorithm is developed in this paper. The principle is described and four different modes of the algorithm are given. Based on computer-simulated images, the optimal mode of the algorithm is verified through the comparison of computation time, optimal subset-region size and sensitivity of the four modes. The influences of speckle-granule size and speckle-granule density on accuracy are studied and a quantitative estimation of the optimal speckle-granule size range is obtained. As the applications of this method, the practical deformation measurements with the rigid body translation and rotation as well as an experiment on biomechanics are presented to certify the feasibility and the validity of the algorithm.