Using Your Beam Efficiently: Reducing Electron-dose in the STEM via Flyback Compensation

TL;DR

This paper introduces a postprocessing correction method for flyback hysteresis in STEM imaging, significantly reducing electron dose and improving dose-efficiency without compromising image quality.

Contribution

It presents a novel calibration and correction technique for flyback hysteresis, enabling minimal flyback time and enhanced dose-efficiency in STEM imaging.

Findings

Up to 20% reduction in electron dose achieved.

Maintains crystallographic and spatial fidelity.

Effective correction of scan-coil hysteresis in postprocessing.

Abstract

In the scanning transmission electron microscope, fast-scanning and frame-averaging are two widely used approaches for reducing electron-beam damage and increasing image signal-noise ratio which require no additional specialised hardware. Unfortunately, for scans with short pixel dwell-times (less than 5 ${\mu}$s), line flyback time represents an increasingly wasteful overhead. Although beam exposure during flyback causes damage while yielding no useful information, scan-coil hysteresis means that eliminating it entirely leads to unacceptably distorted images. In this work, we reduce this flyback to an absolute minimum by calibrating and correcting for this hysteresis in postprocessing. Substantial improvements in dose-efficiency can be realised (up to 20 %), while crystallographic and spatial fidelity is maintained for displacement/strain measurement.