Very-High Dynamic Range, 10,000 Frames/Second Pixel Array Detector for Electron Microscopy

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.

Three-dimensional electron ptychography of organic–inorganic hybrid nanostructures

“…3l). To further improve the quality of the reconstructed 2D phase data and at reduced dose, the use of a newly developed ultrafast detector 53,54,[67][68][69] shows promise. and recording data under cryogenic conditions will further limit radiation damage, as has been demonstrated by by Zhou et al 56 .…”

A Roadmap for Edge Computing Enabled Automated Multidimensional Transmission Electron Microscopy

“…The first such detector used for electron microscopy was the Medipix detector developed at the Diamond Light Source Synchrotron facility in the United Kingdom [34]. The second such effort, also a result of synchrotron detector work, is the Electron Microscope Pixel Array Detector (EMPAD) developed at Cornell University [35,36]. The EMPAD family of detectors is specifically optimized for high dynamic range (HDR), with EMPAD2 reaching a 100,000:1 range for detection.…”

Automatic parameter selection for electron ptychography via Bayesian optimization

“…Ptychography is a computational imaging method that has gained great interests in the electron microscopy community 1 – 4 . The technique was first proposed by Hoppe in 1969 5 and re-invigorated in recent years with the developments of fast electron detectors 6 – 11 that can rapidly collect thousands of diffraction patterns per second. Various iterative reconstruction algorithms have been developed to retrieve the scattering potentials of the sample and the wave function of the illumination from intensity measurements 12 – 14 .…”