Overcoming EBSD indexing challenges using spherical indexing and real space refinement in OIM

Traditionally, electron backscatter diffraction (EBSD) patterns have been indexed in OIM Analysis™ using a combination of the Hough Transform for detecting the bands in the patterns coupled with various band triplet indexing schemes. While this approach has proven robust, it can struggle with samples that produce low-quality patterns. Even with high-quality patterns, the traditional approach is limited in angular resolution, making resolving pseudosymmetry and difficult phase differentiation problems challenging. Dictionary indexing has shown promise for improved indexing of low-quality patterns. OIM Analysis v9 has dramatically improved its dictionary indexing capabilities over v8. Two key developments have been implemented into v9: (1) back-projection of experimental patterns onto a sphere for cross-correlation of the experimental pattern against a dynamically simulated diffraction sphere (spherical indexing) and (2) refinement of crystal orientation using a localized non-linear optimization dictionary indexing approach (real space refinement). This webinar will briefly describe these new developments and then show the application of these techniques with several samples that pose particular challenges to traditional Hough-based indexing, including heavily deformed materials, samples with rough surfaces, materials producing weak diffraction patterns, TKD experiments, difficult-to-differentiate phases, materials exhibiting pseudosymmetry, experiments where angular resolution is important, and more. The advantages and limitations of these new tools within OIM Analysis will be explored.