Improved Three-Dimensional Reconstructions in Electron Ptychography through Defocus Series Measurements

Marcel Schloz; Thomas C Pekin; Hamish G Brown; Dana O Byrne; Bryan D Esser; Emmanuel Terzoudis-Lumsden; Takashi Taniguchi; Kenji Watanabe; Scott D Findlay; Benedikt Haas; Jim Ciston; Christoph T Koch

doi:10.1093/mam/ozae110

Improved Three-Dimensional Reconstructions in Electron Ptychography through Defocus Series Measurements

Microsc Microanal. 2024 Nov 18:ozae110. doi: 10.1093/mam/ozae110. Online ahead of print.

Authors

Affiliations

¹ Department of Physics and Center for the Science of Materials Berlin, Humboldt-Universität zu Berlin, Newtonstraße 15, Berlin 12489, Germany.
² Ian Holmes Imaging Centre, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3010, Australia.
³ Department of Chemistry, University of California, Berkeley, CA 94720, USA.
⁴ National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
⁵ Monash Centre for Electron Microscopy, Monash University, Clayton, Victoria 3800, Australia.
⁶ School of Physics and Astronomy, Monash University, Clayton, Victoria 3800, Australia.
⁷ International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
⁸ Research for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.

PMID: 39558540
DOI: 10.1093/mam/ozae110

Abstract

A detailed analysis of ptychography for three-dimensional (3D) phase reconstructions of thick specimens is performed. We introduce multi-focus ptychography, which incorporates a 4D-STEM defocus series to enhance the quality of 3D reconstructions along the beam direction through a higher overdetermination ratio. This method is compared with established multi-slice ptychography techniques, such as conventional ptychography, regularized ptychography, and multi-mode ptychography. Additionally, we contrast multi-focus ptychography with an alternative method that uses virtual optical sectioning through a reconstructed scattering matrix (S-matrix), which offers more precise 3D structure information compared to conventional ptychography. Our findings from multiple 3D reconstructions based on simulated and experimental data demonstrate that multi-focus ptychography surpasses other techniques, particularly in accurately reconstructing the surfaces and interface regions of thick specimens.

Keywords: 3D reconstruction; 4D-STEM; depth sectioning; ptychography.

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