Use and Verification of Digital Image Correlation for Automated 3-D Surface Characterization in the Scanning Electron Microscope

In this article a technique for automatically characterizing the three-dimensional geometry of fracture surfaces is presented. The technique described utilizes digital image correlation (DIC) to provide an accurate and fast method of digitally reconstructing fracture surfaces from stereo pairs produced in the scanning electron microscope (SEM). Accuracy of photogrammetric relationships, based on the geometry of image formation in the SEM, and errors due to scan distortions are quantified. The technique is used to measure features of known geometry and then applied to a turbine blade, for surface roughness measurement, and a fatigue fracture surface for profile analysis.