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Hÿtch M, Gatel C. Phase detection limits in off-axis electron holography from pixelated detectors: gain variations, geometric distortion and failure of reference-hologram correction. Microscopy (Oxf) 2021; 70:47-58. [PMID: 32744626 DOI: 10.1093/jmicro/dfaa044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/15/2020] [Accepted: 07/27/2020] [Indexed: 11/13/2022] Open
Abstract
We investigate the effect that recording off-axis electron holograms on pixelated detectors, such as charge-coupled devices (CCD) and direct-detection devices (DDD), can have on measured amplitudes and phases. Theory will be developed for the case of perfectly uniform interference fringes illuminating an imperfect detector with gain variations and pixel displacements. We will show that both these types of defect produce a systematic noise in the phase images that depends on the position of the holographic fringes with respect to the detector. Subtracting a reference hologram from the object hologram will therefore not remove the phase noise if the initial phases of the two holograms do not coincide exactly. Another finding is that pi-shifted holograms are much less affected by gain variations but show no improvement concerning geometric distortions. The resulting phase errors will be estimated and simulations presented that confirm the theoretical developments.
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Affiliation(s)
- Martin Hÿtch
- CEMES, Université de Toulouse, CNRS, 29 rue Jeanne Marvig, 31055 Toulouse, France
| | - Christophe Gatel
- CEMES, Université de Toulouse, CNRS, 29 rue Jeanne Marvig, 31055 Toulouse, France
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2
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The Dresden in-situ (S)TEM special with a continuous-flow liquid-helium cryostat. Ultramicroscopy 2019; 203:12-20. [DOI: 10.1016/j.ultramic.2019.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 12/30/2018] [Accepted: 01/21/2019] [Indexed: 11/18/2022]
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3
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Houdellier F, Caruso GM, Weber S, Hÿtch MJ, Gatel C, Arbouet A. Optimization of off-axis electron holography performed with femtosecond electron pulses. Ultramicroscopy 2019; 202:26-32. [PMID: 30933740 DOI: 10.1016/j.ultramic.2019.03.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 03/19/2019] [Accepted: 03/25/2019] [Indexed: 11/25/2022]
Abstract
We report on electron holography experiments performed with femtosecond electron pulses in an ultrafast coherent Transmission Electron Microscope based on a laser-driven cold field emission gun. We first discuss the experimental requirements related to the long acquisition times imposed by the low emission/probe current available in these instruments. The experimental parameters are first optimized and electron holograms are then acquired in vacuum and on a nano-object showing that useful physical properties can nevertheless be extracted from the hologram phase in pulsed condition. Finally, we show that the acquisition of short exposure time holograms assembled in a stack, combined with a computer-assisted shift compensation of usual instabilities encountered in holography, such as beam and biprism wire instabilities, can yield electron holograms acquired with a much better contrast paving the way to ultrafast time-resolved electron holography.
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Affiliation(s)
- F Houdellier
- CEMES-CNRS, Université de Toulouse, Toulouse, France.
| | - G M Caruso
- CEMES-CNRS, Université de Toulouse, Toulouse, France
| | - S Weber
- CEMES-CNRS, Université de Toulouse, Toulouse, France
| | - M J Hÿtch
- CEMES-CNRS, Université de Toulouse, Toulouse, France
| | - C Gatel
- CEMES-CNRS, Université de Toulouse, Toulouse, France
| | - A Arbouet
- CEMES-CNRS, Université de Toulouse, Toulouse, France.
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4
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Off-axis electron holography combining summation of hologram series with double-exposure phase-shifting: Theory and application. Ultramicroscopy 2018; 193:52-63. [DOI: 10.1016/j.ultramic.2018.06.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/30/2018] [Accepted: 06/03/2018] [Indexed: 11/23/2022]
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Winkler F, Barthel J, Tavabi AH, Borghardt S, Kardynal BE, Dunin-Borkowski RE. Absolute Scale Quantitative Off-Axis Electron Holography at Atomic Resolution. PHYSICAL REVIEW LETTERS 2018; 120:156101. [PMID: 29756849 DOI: 10.1103/physrevlett.120.156101] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Indexed: 06/08/2023]
Abstract
An absolute scale match between experiment and simulation in atomic-resolution off-axis electron holography is demonstrated, with unknown experimental parameters determined directly from the recorded electron wave function using an automated numerical algorithm. We show that the local thickness and tilt of a pristine thin WSe_{2} flake can be measured uniquely, whereas some electron optical aberrations cannot be determined unambiguously for a periodic object. The ability to determine local specimen and imaging parameters directly from electron wave functions is of great importance for quantitative studies of electrostatic potentials in nanoscale materials, in particular when performing in situ experiments and considering that aberrations change over time.
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Affiliation(s)
- Florian Winkler
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, 52425 Jülich, Germany
- Peter Grünberg Institute 5 (PGI-5), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Juri Barthel
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, 52425 Jülich, Germany
- Gemeinschaftslabor für Elektronenmikroskopie (GFE), RWTH Aachen University, 52074 Aachen, Germany
| | - Amir H Tavabi
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, 52425 Jülich, Germany
- Peter Grünberg Institute 5 (PGI-5), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Sven Borghardt
- Peter Grünberg Institute 9 (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Beata E Kardynal
- Peter Grünberg Institute 9 (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, 52425 Jülich, Germany
- Peter Grünberg Institute 5 (PGI-5), Forschungszentrum Jülich, 52425 Jülich, Germany
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6
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Ultrafast Transmission Electron Microscopy: Historical Development, Instrumentation, and Applications. ADVANCES IN IMAGING AND ELECTRON PHYSICS 2018. [DOI: 10.1016/bs.aiep.2018.06.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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7
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Duchamp M, Girard O, Pozzi G, Soltner H, Winkler F, Speen R, Dunin-Borkowski RE, Cooper D. Fine electron biprism on a Si-on-insulator chip for off-axis electron holography. Ultramicroscopy 2017; 185:81-89. [PMID: 29223803 DOI: 10.1016/j.ultramic.2017.11.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 11/15/2017] [Accepted: 11/19/2017] [Indexed: 11/16/2022]
Abstract
Off-axis electron holography allows both the amplitude and the phase shift of an electron wavefield propagating through a specimen in a transmission electron microscope to be recovered. The technique requires the use of an electron biprism to deflect an object wave and a reference wave to form an interference pattern. Here, we introduce an approach based on semiconductor processing technology to fabricate fine electron biprisms with rectangular cross-sections. By performing electrostatic calculations and preliminary experiments, we demonstrate that such biprisms promise improved performance for electron holography experiments.
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Affiliation(s)
- Martial Duchamp
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore ; Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich, 52425 Jülich, Germany.
| | - Olivier Girard
- Université Grenoble Alpes, 38000 Grenoble, France; CEA, LETI, MINATEC Campus, 38054 Grenoble, France
| | - Giulio Pozzi
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich, 52425 Jülich, Germany; Department of Physics and Astronomy, University of Bologna, viale B. Pichat 6/2, 40127 Bologna, Italy
| | - Helmut Soltner
- Central Institute of Engineering, Electronics and Analytics (ZEA-1), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Florian Winkler
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Rolf Speen
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - David Cooper
- Université Grenoble Alpes, 38000 Grenoble, France; CEA, LETI, MINATEC Campus, 38054 Grenoble, France
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Performance of a direct detection camera for off-axis electron holography. Ultramicroscopy 2016; 161:90-97. [DOI: 10.1016/j.ultramic.2015.09.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 08/21/2015] [Accepted: 09/11/2015] [Indexed: 11/22/2022]
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9
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Chang SL, Dwyer C, Boothroyd CB, Dunin-Borkowski RE. Optimising electron holography in the presence of partial coherence and instrument instabilities. Ultramicroscopy 2015; 151:37-45. [DOI: 10.1016/j.ultramic.2014.11.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 11/10/2014] [Accepted: 11/10/2014] [Indexed: 11/24/2022]
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10
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Niermann T, Lehmann M. Averaging scheme for atomic resolution off-axis electron holograms. Micron 2014; 63:28-34. [DOI: 10.1016/j.micron.2014.01.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 01/27/2014] [Accepted: 01/28/2014] [Indexed: 10/25/2022]
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11
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McLeod RA, Bergen M, Malac M. Phase measurement error in summation of electron holography series. Ultramicroscopy 2014; 141:38-50. [DOI: 10.1016/j.ultramic.2014.03.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 03/02/2014] [Accepted: 03/09/2014] [Indexed: 11/29/2022]
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Lichte H, Börrnert F, Lenk A, Lubk A, Röder F, Sickmann J, Sturm S, Vogel K, Wolf D. Electron holography for fields in solids: problems and progress. Ultramicroscopy 2013; 134:126-34. [PMID: 23831133 DOI: 10.1016/j.ultramic.2013.05.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 05/13/2013] [Accepted: 05/14/2013] [Indexed: 11/18/2022]
Abstract
Electron holography initially was invented by Dennis Gabor for solving the problems raised by the aberrations of electron lenses in Transmission Electron Microscopy. Nowadays, after hardware correction of aberrations allows true atomic resolution of the structure, for comprehensive understanding of solids, determination of electric and magnetic nanofields is the most challenging task. Since fields are phase objects in the TEM, electron holography is the unrivaled method of choice. After more than 40 years of experimental realization and steady improvement, holography is increasingly contributing to these highly sophisticated and essential questions in materials science, as well to the understanding of electron waves and their interaction with matter.
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Affiliation(s)
- Hannes Lichte
- Triebenberg Laboratory, Institute of Structure Physics, Technische Universität Dresden, Zum Triebenberg 50, 01328 Dresden, Germany.
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Lichte H, Geiger D, Linck M. Off-axis electron holography in an aberration-corrected transmission electron microscope. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2009; 367:3773-3793. [PMID: 19687065 DOI: 10.1098/rsta.2009.0126] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Electron holography allows the reconstruction of the complete electron wave, and hence offers the possibility of correcting aberrations. In fact, this was shown by means of the uncorrected CM30 Special Tübingen transmission electron microscope (TEM), revealing, after numerical aberration correction, a resolution of approximately 0.1 nm, both in amplitude and phase. However, it turned out that the results suffer from a comparably poor signal-to-noise ratio. The reason is that the limited coherent electron current, given by gun brightness, has to illuminate a width of at least four times the point-spread function given by the aberrations. As, using the hardware corrector, the point-spread function shrinks considerably, the current density increases and the signal-to-noise ratio improves correspondingly. Furthermore, the phase shift at the atomic dimensions found in the image plane also increases because the collection efficiency of the optics increases with resolution. In total, the signals of atomically fine structures are better defined for quantitative evaluation. In fact, the results achieved by electron holography in a Tecnai F20 Cs-corr TEM confirm this.
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Affiliation(s)
- Hannes Lichte
- Triebenberg Laboratory, Institute of Structure Physics, Technische Universität Dresden, Germany.
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Geiger D, Lichte H, Linck M, Lehmann M. Electron holography with a Cs-corrected transmission electron microscope. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2008; 14:68-81. [PMID: 18096096 DOI: 10.1017/s143192760808001x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 07/21/2007] [Indexed: 05/25/2023]
Abstract
Cs correctors have revolutionized transmission electron microscopy (TEM) in that they substantially improve point resolution and information limit. The object information is found sharply localized within 0.1 nm, and the intensity image can therefore be interpreted reliably on an atomic scale. However, for a conventional intensity image, the object exit wave can still not be detected completely in that the phase, and hence indispensable object information is missing. Therefore, for example, atomic electric-field distributions or magnetic domain structures cannot be accessed. Off-axis electron holography offers unique possibilities to recover completely the aberration-corrected object wave with uncorrected microscopes and hence we would not need a Cs-corrected microscope for improved lateral resolution. However, the performance of holography is affected by aberrations of the recording TEM in that the signal/noise properties ("phase detection limit") of the reconstructed wave are degraded. Therefore, we have realized off-axis electron holography with a Cs-corrected TEM. The phase detection limit improves by a factor of four. A further advantage is the possibility of fine-tuning the residual aberrations by a posteriori correction. Therefore, a combination of both methods, that is, Cs correction and off-axis electron holography, opens new perspectives for complete TEM analysis on an atomic scale.
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Affiliation(s)
- Dorin Geiger
- Institute for Structure Physics, Triebenberg Laboratory, Technische Universität Dresden, D-01062 Dresden, Germany.
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15
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Smith DJ. Development of aberration-corrected electron microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2008; 14:2-15. [PMID: 18171498 DOI: 10.1017/s1431927608080124] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2007] [Accepted: 08/07/2007] [Indexed: 05/25/2023]
Abstract
The successful correction of spherical aberration is an exciting and revolutionary development for the whole field of electron microscopy. Image interpretability can be extended out to sub-Angstrom levels, thereby creating many novel opportunities for materials characterization. Correction of lens aberrations involves either direct (online) hardware attachments in fixed-beam or scanning TEM or indirect (off-line) software processing using either off-axis electron holography or focal-series reconstruction. This review traces some of the important steps along the path to realizing aberration correction, including early attempts with hardware correctors, the development of online microscope control, and methods for accurate measurement of aberrations. Recent developments and some initial applications of aberration-corrected electron microscopy using these different approaches are surveyed. Finally, future prospects and problems are briefly discussed.
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Affiliation(s)
- David J Smith
- Department of Physics, Arizona State University, Tempe, Arizona 85287-1504, USA.
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Lehmann M. Exit surface dependence of the wavefunction measured and corrected by means of off-axis electron holography. ACTA ACUST UNITED AC 2005. [DOI: 10.1002/pssa.200521269] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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Lehmann M, Lichte H. Electron holographic material analysis at atomic dimensions. CRYSTAL RESEARCH AND TECHNOLOGY 2005. [DOI: 10.1002/crat.200410318] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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