How Fast is Your Detector? The Effect of Temporal Response on Image Quality

TL;DR

This paper investigates the temporal response of various STEM detectors and demonstrates how their response times impact image quality, providing a methodology to evaluate and compare detector performance for high-speed imaging applications.

Contribution

It introduces a comprehensive methodology for measuring and incorporating detector temporal response into simulations, and compares solid-state and PMT detectors for optimal image quality.

Findings

Solid-state detectors outperform PMT detectors in most performance metrics.

Temporal response significantly affects image resolution and Fourier transform quality.

A new evaluation framework helps select suitable detectors for specific applications.

Abstract

With increasing interest in high-speed imaging should come an increased interest in the response times of our scanning transmission electron microscope (STEM) detectors. Previous works have previously highlighted and contrasted performance of various detectors for quantitative compositional or structural studies, but here we shift the focus to detector temporal response, and the effect this has on captured images. The rise and decay times of eight detectors' single electron response are reported, as well as measurements of their flatness, roundness, smoothness, and ellipticity. We develop and apply a methodology for incorporating the temporal detector response into simulations, showing that a loss of resolution is apparent in both the images and their Fourier transforms. We conclude that the solid-state detector outperforms the photomultiplier-tube (PMT) based detectors in all areas bar a slightly less elliptical central hole and is likely the best detector to use for the majority of applications. However, using tools introduced here we encourage users to effectively evaluate what detector is most suitable for their experimental needs.