78 J. Heikkinen and G. S. Schajer sizes are computed for small local patches across the image, the resulting map of speckle sizes can provide an approximate estimation of the object shape and thus supplying the required spatially varying calibration parameters for the 2D-DIC analysis. Acknowledgments The authors gratefully thank Jenny and Antti Wihuri Foundation, Helsinki, Finland, and Stresstech Oy, Vaajakoski, Finland, for their long-term financial support of this research. References 1. Sutton, M., Wolters, W., Peters, W., Ranson, W., McNeill, S.: Determination of displacements using an improved digital correlation method. Image Vis. Comput. 1(3), 133–139 (1983) 2. Archbold, E., Ennos, A.: Displacement measurement from double-exposure laser photographs. Optica Acta Int. J. Optics. 19(4), 253–271 (1972) 3. Horvath, P., Hrabovský, M., Smid, P.: Full theory of speckle displacement and decorrelation in the image field by wave and geometrical descriptions and its application in mechanics. J. Mod. Opt. 51(5), 725–742 (2004) 4. Heikkinen, J., Schajer, G.: A geometric model of surface motion measurement by objective speckle imaging. Opt. Lasers Eng. 124, Article 105850 (2020) 5. Heikkinen, J., Schajer, G.: Remote surface motion measurements using defocused speckle imaging. Opt. Lasers Eng. 130, 106091 (2020) 6. Cloud, G.: Optical methods in experimental mechanics part 27: speckle size estimates. Exp. Tech. 31(3), 19–22 (2007)
RkJQdWJsaXNoZXIy MTMzNzEzMQ==