A Confidence Index for eCHORD Orientation Mapping

Authors:
Publisher website
Google Scholar
Abstract
Orientation mapping techniques such as electron backscatter diffraction (EBSD) and automated crystal orientation mapping technique (ACOM-TEM) rely on dedicated quality metrics to assess the reliability of crystallographic indexing at each pixel. The eCHORD technique (electron CHanneling ORientation Determination), which recovers crystalline orientations in a standard scanning electron microscope by matching experimental backscattered electrons intensity profiles against a database of theoretical profiles, currently lacks such a robust confidence indicator. This work introduces a confidence index for eCHORD orientation mapping based on the windowed normalized cross-correlation index (wNCC) between experimental and theoretical profiles evaluated over sliding angular windows. Unlike the Euclidean distance used in the standard indexing step, the wNCC is sensitive to local profile discrepancies and provides a per-pixel reliability estimate directly analogous to the confidence index in EBSD or the reliability index in ACOM-TEM. The index was validated on three materials—an aluminum alloy, a copper microelectronic pad, and an α-titanium sample—and across several acquisition and indexing conditions. It successfully identifies unreliable pixels at grain boundaries, surface defects, and within poorly indexed grains, and constitutes an effective confidence metric within the eCHORD framework.

This publication has 33 references indexed in Scilit: