Transmission Kikuchi Diffraction Simulation for Cross-Correlation Analysis

Transmission Kikuchi diffraction (TKD) is a scanning electron microscopy technique combining imaging and diffraction to identify phases and map crystal orientations. TKD allows for real space and reciprocal space to be detected simultaneously. Using a Hough transform-based indexing routine, the diffraction information can be analyzed in real-time from a region of the crystal only a few nanometers wide. The TKD patterns also contain information that is subtler, such as temperature and strain, that come from small changes in lattice parameters. Extracting these details requires more sensitivity than can be achieved with the traditional Hough method. New cross-correlation based techniques, where the experimental patterns are compared with simulated ones, can achieve the necessary sensitivity. But results vary depending on how faithfully the diffraction patterns are simulated. For instance, one can choose to take a kinematic or a dynamical approach, to account for the Debye-Waller effect, or to consider the background intensity from inelastically scattered electrons. In this work, we compare different simulation methods and propose a TKD pattern simulation routine that balances sensitivity with computational cost. The result is a measurement of spatially varying strain in materials at a precision on the parts-per thousand level.