Global DIC-based sample-detector geometry refinement for accurate EBSD indexing

TL;DR

This paper introduces a DIC-based method for refining the sample-detector geometry in EBSD, improving orientation accuracy and robustness in challenging materials by globally calibrating pattern shifts.

Contribution

The authors propose a novel global geometry refinement technique that simultaneously refines pattern center and angles, enhancing EBSD accuracy over existing local calibration methods.

Findings

Improved map-wide orientation consistency in silicon and barium titanate.

More robust discrimination of pseudosymmetric variants compared to Nelder-Mead and Differential Evolution.

Effective decoupling of local orientation changes from global geometry effects.

Abstract

Electron backscatter diffraction is a powerful tool for mapping crystallographic microstructures. However, the primary crux to improving orientation accuracy and applying the technique to challenging materials lies in the correct calibration of the sample-detector geometry. Many approaches have aimed at overcoming this barrier through various pattern center calibration strategies, but the pattern center only defines part of the sample-detector geometry. Here, we present a DIC-based geometry refinement method that obtains a single map-consistent sample-detector geometry, refining both the pattern center and sample/detector angles. We effectively decouple the local orientation changes from the global geometry effects on the Kikuchi patterns by calculating the consistent map-wide simulated-to-experimental pattern shifts associated with global geometry parameter errors. Using single-crystal silicon and barium titanate (a material possessing six pseudosymmetric variants) as model materials, we demonstrate improved map-wide orientation consistency and more robust discrimination of pseudosymmetric variants than the Nelder-Mead and Differential Evolution optimization strategies.