Graphical AbstractAbstract Electron backscatter diffraction (EBSD) is a well-established method of characterisation for crystalline materials. Using this technique, we can rapidly acquire and index diffraction patterns to provide phase and orientation information about the crystals on the material surface. The conventional analysis method uses signal processing based on a Hough/Radon transform to index each diffraction pattern. This method is limited to the analysis of simple geometric features and ignores subtle characteristics of diffraction patterns, such as variations in relative band intensities. A second method, developed to address the shortcomings of the Hough/Radon transform, is based on template matching of a test experimental pattern with a large library of potential patterns. In the present work, the template matching approach has been refined with a new cross correlation function that allows for a smaller library and enables a dramatic speed up in pattern indexing. Refinement of the indexed orientation is performed with a follow-up step to allow for small alterations to the best match from the library search. The refined template matching approach is shown to be comparable in accuracy, precision and sensitivity to the Hough based method, even exceeding it in some cases, via the use of simulations and experimental data collected from a silicon single crystal and a deformed α-iron sample. The speed up and pattern refinement approaches should increase the widespread utility of pattern matching approaches.

Electron backscatter diffraction (EBSD) is a well-established characterisation technique used to gain information about the surface of crystalline materials. An electron beam is focussed on the surface of a sample, scattering with diffraction occurs in the near surface lattice generating electrons that exit the sample over a wide range of angles. An electron backscatter pattern (EBSP) can be collected on a screen and records the angular distribution of the emitted electrons. EBSPs correspond to direct projections of the lattice planes beyond the crystal; crystal orientation measurement and phase identification relies on the property that there are constant interplanar angles, which are invariant with respect to lattice rotation [1]. The indexing of EBSPs is usually done using an image processing technique called the Hough (a subset of the Radon) transform. The Hough transform converts lines seen in the pattern to points, which can be easily located by computationally methods. The interplanar angles are then found in "Hough-space" and compared to a look-up table to determine the phase and orientation of the lattice [2]. For most conventional uses, the Hough based indexing approach is sufficient, however, the Hough based indexing method often only considers the band centres, ignoring band width, intensity profile across bands and Secondary bands. This limits the accuracy and precision to how well the crystal orientation can be determined. It also limits accurate and precise measurements to be made on simple crystal structures where subtle features in the EBSP are not necessary for indexing [3].

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