Diffraction-Assisted Image Correlation for Three-Dimensional Surface Profiling

The recently developed Diffraction-Assisted Image Correlation (DAIC) method (Xia et al. Exp Mech 53(5):755-765, 2013) provides a simple and accurate means for three-dimensional (3D) full-field deformation measurement. In the DAIC method, a test specimen is viewed through a transmission diffraction grating, resulting in multiple diffracted views of the same specimen that encode 3D geometric information. Here, we extend the original DAIC method to permit quantitative measurement of 3D surface profiles. We show, through a pinhole projection model, that the 3D shape of an object surface can be reconstructed by simply performing two-dimensional digital image correlation (2D-DIC) analysis between the negative and positive first-order diffracted views. Test results on a Barbie doll's face and a set of well-defined cylindrical, conical and step surfaces are presented to illustrate the implementation and performance of the proposed surface profiling method.