Very-High Dynamic Range, 10,000 frames/second Pixel Array Detector for Electron Microscopy

TL;DR

The paper introduces the EMPAD-G2, a high-speed, high-dynamic-range pixel detector for electron microscopy that enables rapid, high-quality data collection and advanced imaging techniques like ptychography and strain mapping.

Contribution

The EMPAD-G2 advances pixel array detector technology by achieving 10,000 fps with wide dynamic range, supporting detailed electron microscopy imaging and analysis.

Findings

Achieves 10,000 frames per second imaging rate.

Supports detection of single electrons and high beam currents.

Enables high-quality ptychography and strain mapping.

Abstract

Precision and accuracy of quantitative scanning transmission electron microscopy (STEM) methods such as ptychography, and the mapping of electric, magnetic and strain fields depend on the dose. Reasonable acquisition time requires high beam current and the ability to quantitatively detect both large and minute changes in signal. A new hybrid pixel array detector (PAD), the second-generation Electron Microscope Pixel Array Detector (EMPAD-G2), addresses this challenge by advancing the technology of a previous generation PAD, the EMPAD. The EMPAD-G2 images continuously at a frame-rates up to 10 kHz with a dynamic range that spans from low-noise detection of single electrons to electron beam currents exceeding 180 pA per pixel, even at electron energies of 300 keV. The EMPAD-G2 enables rapid collection of high-quality STEM data that simultaneously contain full diffraction information from unsaturated bright field disks to usable Kikuchi bands and higher-order Laue zones. Test results from 80 to 300 keV are presented, as are first experimental results demonstrating ptychographic reconstructions, strain and polarization maps. We introduce a new information metric, the Maximum Usable Imaging Speed (MUIS), to identify when a detector becomes electron-starved, saturated or its pixel count is mismatched with the beam current.