中国物理B ›› 2024, Vol. 33 ›› Issue (11): 116803-116803.doi: 10.1088/1674-1056/ad8554

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Making the link between ADF and 4D STEM: Resolution, transfer and coherence

Peter D. Nellist1,† and Timothy J. Pennycook2   

  1. 1 Department of Materials, University of Oxford, Oxford, UK;
    2 EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
  • 收稿日期:2024-09-03 修回日期:2024-10-05 接受日期:2024-10-10 出版日期:2024-11-15 发布日期:2024-11-15
  • 基金资助:
    We acknowledge funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme via Grant Agreement No. 802123-HDEM (TJP) and from the UK Engineering and Physical Sciences Research Council (EPSRC) via grant EP/M010708/1 (PDN).

Making the link between ADF and 4D STEM: Resolution, transfer and coherence

Peter D. Nellist1,† and Timothy J. Pennycook2   

  1. 1 Department of Materials, University of Oxford, Oxford, UK;
    2 EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
  • Received:2024-09-03 Revised:2024-10-05 Accepted:2024-10-10 Online:2024-11-15 Published:2024-11-15
  • Contact: Peter D. Nellist E-mail:peter.nellist@materials.ox.ac.uk
  • Supported by:
    We acknowledge funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme via Grant Agreement No. 802123-HDEM (TJP) and from the UK Engineering and Physical Sciences Research Council (EPSRC) via grant EP/M010708/1 (PDN).

摘要: Steve Pennycook is a pioneer in the application of high-resolution scanning transmission electron microscopy (STEM) and in particular the use of annular dark-field (ADF) imaging. Here we show how a general framework for 4D STEM allows clear links to be made between ADF imaging and the emerging methods for reconstructing images from 4D STEM data sets. We show that both ADF imaging and ptychographical reconstruction can be thought of in terms of integrating over the overlap regions of diffracted discs in the detector plane. This approach allows the similarities in parts of their transfer functions to be understood, though we note that the transfer functions for ptychographic imaging cannot be used as a measure of information transfer. We also show that conditions of partial spatial and temporal coherence affect ADF imaging and ptychography similarly, showing that achromatic interference can always contribute to the image in both cases, leading to a robustness to partial temporal coherence that has enabled high-resolution imaging.

关键词: image forming and processing, phase retrieval, electron microscopy, scanning transmission electron microscope (STEM)

Abstract: Steve Pennycook is a pioneer in the application of high-resolution scanning transmission electron microscopy (STEM) and in particular the use of annular dark-field (ADF) imaging. Here we show how a general framework for 4D STEM allows clear links to be made between ADF imaging and the emerging methods for reconstructing images from 4D STEM data sets. We show that both ADF imaging and ptychographical reconstruction can be thought of in terms of integrating over the overlap regions of diffracted discs in the detector plane. This approach allows the similarities in parts of their transfer functions to be understood, though we note that the transfer functions for ptychographic imaging cannot be used as a measure of information transfer. We also show that conditions of partial spatial and temporal coherence affect ADF imaging and ptychography similarly, showing that achromatic interference can always contribute to the image in both cases, leading to a robustness to partial temporal coherence that has enabled high-resolution imaging.

Key words: image forming and processing, phase retrieval, electron microscopy, scanning transmission electron microscope (STEM)

中图分类号:  (Scanning transmission electron microscopy (STEM))

  • 68.37.Ma
42.30.Va (Image forming and processing) 42.30.Rx (Phase retrieval) 87.64.Ee (Electron microscopy)