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O'Leary CM, Martinez GT, Liberti E, et al. Contrast transfer and noise considerations in focused-probe electron ptychography. Ultramicroscopy. 2020;221:113189doi: 10.1016/j.ultramic.2020.113189.
O'Leary, C. M., Martinez, G. T., Liberti, E., Humphry, M. J., Kirkland, A. I., & Nellist, P. D. (2021). Contrast transfer and noise considerations in focused-probe electron ptychography. Ultramicroscopy, 221113189. https://doi.org/10.1016/j.ultramic.2020.113189
O'Leary, Colum M, et al. "Contrast transfer and noise considerations in focused-probe electron ptychography." Ultramicroscopy vol. 221 (2021): 113189. doi: https://doi.org/10.1016/j.ultramic.2020.113189
O'Leary CM, Martinez GT, Liberti E, Humphry MJ, Kirkland AI, Nellist PD. Contrast transfer and noise considerations in focused-probe electron ptychography. Ultramicroscopy. 2021 Feb;221:113189. doi: 10.1016/j.ultramic.2020.113189. Epub 2020 Dec 17. PMID: 33360480.
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Ultramicroscopy. 2021 Feb;221:113189. doi: 10.1016/j.ultramic.2020.113189. Epub 2020 Dec 17.

Contrast transfer and noise considerations in focused-probe electron ptychography.

Ultramicroscopy

Colum M O'Leary, Gerardo T Martinez, Emanuela Liberti, Martin J Humphry, Angus I Kirkland, Peter D Nellist

Affiliations

  1. Department of Materials, University of Oxford, Parks Rd, Oxford OX13PH, United Kingdom. Electronic address: [email protected].
  2. Department of Materials, University of Oxford, Parks Rd, Oxford OX13PH, United Kingdom.
  3. Department of Materials, University of Oxford, Parks Rd, Oxford OX13PH, United Kingdom; electron Physical Science Imaging Centre (ePSIC), Diamond Light Source, Didcot OX11 0DE, United Kingdom.
  4. Phase Focus Ltd, Electric Works, Sheffield Digital Campus, Sheffield S1 2BJ, United Kingdom.
  5. Department of Materials, University of Oxford, Parks Rd, Oxford OX13PH, United Kingdom; electron Physical Science Imaging Centre (ePSIC), Diamond Light Source, Didcot OX11 0DE, United Kingdom; The Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot OX11 0FA, United Kingdom.

PMID: 33360480 DOI: 10.1016/j.ultramic.2020.113189

Abstract

Electron ptychography is a 4-D STEM phase-contrast imaging technique with applications to light-element and beam-sensitive materials. Although the electron dose (electrons incident per unit area on the sample) is the primary figure of merit for imaging beam-sensitive materials, it is also necessary to consider the contrast transfer properties of the imaging technique. Here, we explore the contrast transfer properties of electron ptychography. The contrast transfer of focused-probe, non-iterative electron ptychography using the single-side-band (SSB) method is demonstrated experimentally. The band-pass nature of the phase-contrast transfer function (PCTF) for SSB ptychography places strict limitations on the probe convergence semi-angles required to resolve specific sample features with high contrast. The PCTF of the extended ptychographic iterative engine (ePIE) is broader than that for SSB ptychography, although when both high and low spatial frequencies are transferred, band-pass filtering is required to remove image artefacts. Normalisation of the transfer function with respect to the noise level shows that the transfer window is increased while avoiding noise amplification. Avoiding algorithms containing deconvolution steps may also increase the dose-efficiency of ptychographic phase reconstructions.

Copyright © 2021 Elsevier B.V. All rights reserved.

Keywords: Contrast transfer function; Focused-probe electron ptychography; Single side-band method

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