ISBN: 3-540-64555-1
TITLE: Electron Holography
AUTHOR: Tonomura, Akira
TOC:

1. Introduction 1 
2. Principles of Holography 2 
2.1 In-Line Holography 3 
2.2 Off-Axis Holography 6 
2.3 Holography Using Two Different Kinds of Waves 8 
3. Electron Optics 10 
3.1 Electron Microscopy 10 
3.1.1 Ray Diagram 10 
3.1.2 Electron Guns 10 
3.1.3 Electron Lenses 12 
3.2 Interference Electron Microscope 13 
3.3 Coherence Properties of Electron Beams 15 
3.3.1 Temporal Coherence 16 
3.3.2 Spatial Coherence 17 
4. Historical Development of Electron Holography 20 
4.1 In-Line Holography 21 
4.2 Off-Axis Holography 25 
5. Electron Holography 29 
5.1 Electron-Hologram Formation 29 
5.1.1 Ray Diagram 29 
5.1.2 Experimental Apparatus 31 
a) Electron Gun and Illumination System 31 
b) Electron Interferometer 32 
c) Recording System 33 
5.2 Image Reconstruction 34 
5.2.1 Interference Microscopy 34 
5.2.2 Phase-Amplified Interference Microscopy 36 
a) Optical Method 36 
b) Numerical Method 39 
c) Phase-Shifting Method in Optical Reconstruction 39 
d) Phase-Shifting Method in Electron Microscopy 40 
5.2.3 Three- Dimensional Imaging Reconstruction 41 
5.2.4 Real-Time Observations 42 
5.2.5 Image Restoration by Aberration Compensation 44 
5.2.6 Micro-Area Electron Diffraction 47 
6. Aharonov-Bohm Effect: 
The Principle Behind the Interaction of Electrons 
with Electromagnetic Fields 50 
6.1 What is the Aharonov-Bohm Effect 51 
6.2 Unusual Features of the Aharonov-Bohm Effect: 
Modified Double-Slit Experiments 53 
6.3 The History of Vector Potentials 55 
6.4 Fiber-Bundle Description of the Aharonov-Bohm Effect 56 
6.5 Early Experiments and Controversy 60 
6.5.1 Early Experiments 60 
6.5.2 Nonexistence of the Aharonov-Bohm Effect 61 
a) Non-Stokesian Vector Potential 61 
b) Hydrodynamical Formulation 62 
c) Doubts About the Validity of Early Experiments 63 
6.5.3 Dispute About the Nonexistence 
of the Aharonov Bohm Effect 63 
a) Non-Stokesian Vector Potentials 63 
b) Hydrodynamical Formulation 64 
c) Discussions on the Validity of Experiments 65 
6.6 Experiments Confirming the Aharonov-Bohm Effect 66 
6.6.1 An Experiment Using Transparent Toroidal Magnets 66 
a) Sample Preparation 66 
b) Experimental Results 68 
c) Discussions of the Validity of the Experiment 69 
6.6.2 An Experiment Using Toroidal Magnets 
Covered with a Superconducting Film 70 
a) Sample Preparation 70 
b) Experimental Results 72 
7. Electron-Holographic Interferometry 78 
7.1 Thickness Measurements 78 
7.1.1 Principle of the Measurement 78 
7.1.2 Examples of Thickness Measurement 79 
7.1.3 Other Applications 82 
7.2 Surface Topography 83 
7.3 Electric Field Distribution 84 
7.4 Domain Structures in Ferromagnetic Thin Films 85 
7.4.1 Measurement Principles 85 
7.4.2 Magnetic Domain Walls in Thin Films 87 
7.5 Domain Structures in Fine Ferromagnetic Particles 90 
7.6 Magnetic Devices 93 
7.7 Domain Structures in Three-Dimensional Particles 96 
7.8 Three-Dimensional Image 99 
7.8.1 Electric Potentials 99 
7.8.2 Magnetic Fields 100 
7.9 Dynamic Observation of Domain Structures 102 
7.10 Static Observation of Fluxons in the Profile Mode 103 
7.10.1 Quantized Flux (Fluxons) 103 
7.10.2 Experimental Method 104 
7.10.3 Experimental Results 105 
7.11 Dynamic Observation of Fluxons in the Profile Mode 108 
7.11.1 Thermally Excited Fluxons 108 
7.11.2 Current-Driven Fluxons 110 
a) Experimental Method 1ll 
b) Experimental Results 116 
7.12 Observation of Fluxons in the Transmission Mode 117 
7.12.1 Experimental Methods 117 
7.12.2 Experimental Results 118 
a) Behavior of Fluxons in Nb Thin Films 118 
b) Estimation of Pinning Forces of Defects 121 
c) Intermittent Rivers of Fluxons 122 
d) Matching Effect 124 
e) High-Tc Superconductors 130 
8. High-Resolution Microscopy 133 
8.1 Phase Contrast Due to Aberration and Defocusing 133 
8.2 Optical Correction of Spherical Aberration 138 
8.2.1 In-Focus Electron Micrograph 
of a Crystalline Particle 138 
8.2.2 Off-Axis Hologram of a Crystalline Particle 139 
8.2.3 Image Reconstruction 141 
8.2.4 Spherical Aberration Correction 141 
8.3 Numerical Correction of Spherical Aberration 143 
9. Conclusions 146 
References 147 
Subject Index 159 
END
