Space rocks and optimising scanning electron channelling contrast

TL;DR

This paper investigates how to optimize forescatter electron imaging in scanning electron microscopes for better qualitative and quantitative microstructural analysis by adjusting sample and detector positioning.

Contribution

It systematically explores the relationship between detector positioning and contrast modes, enhancing the understanding of optimizing forescatter electron imaging.

Findings

Optimal detector positions improve contrast for topography, phase, and orientation.

Comparison with pseudo-forescatter images confirms contrast mechanisms.

Application demonstrated on Gibeon meteorite sample.

Abstract

Forescatter electron imaging is a popular microscopy technique, especially for scanning electron microscopes equipped with an electron backscatter diffraction detector. In principal, this method enables qualitative imaging of microstructure but quantitative assessment can be limited due to limited information about the contrast afforded. In this work, we explore forescatter electron imaging and demonstrate that imaging can be optimised for topographic, phase, and subtle orientation contrast imaging through appropriate sample and detector positioning. We demonstrate the relationship between imaging modes using systematic variation in detector positioning and compare this with pseudo-forescatter electron images, obtained from image analysis of diffraction patterns, to explore and confirm image contrast modes. We demonstrate these contrast mechanisms on a map obtained from a sample of the Gibeon meteorite.