Reconstruction of electron holograms recorded in a non-FEG, non-biprism TEM

Author(s):  
Z.L. Wang

An experimental technique for performing electron holography using a non-FEG, non-biprism transmission electron microscope (TEM) has been introduced by Ru et al. A double stacked specimens, one being a single crystal foil and the other the specimen, are loaded in the normal specimen position in TEM. The single crystal, which is placed onto the specimen, is responsible to produce two beams that are equivalent to two virtual coherent sources illuminating the specimen beneath, thus, permitting electron holography of the specimen. In this paper, the imaging theory of this technique is described. Procedures are introduced for digitally reconstructing the holograms.

Author(s):  
D. S. Pritchard

The effect of varying the strain rate loading conditions in compression on a copper single crystal dispersion-hardened with SiO2 particles has been examined. These particles appear as small spherical inclusions in the copper lattice and have a volume fraction of 0.6%. The structure of representative crystals was examined prior to any testing on a transmission electron microscope (TEM) to determine the nature of the dislocations initially present in the tested crystals. Only a few scattered edge and screw dislocations were viewed in those specimens.


2000 ◽  
Vol 6 (S2) ◽  
pp. 228-229
Author(s):  
M. A. Schofield ◽  
Y. Zhu

Quantitative off-axis electron holography in a transmission electron microscope (TEM) requires careful design of experiment specific to instrumental characteristics. For example, the spatial resolution desired for a particular holography experiment imposes requirements on the spacing of the interference fringes to be recorded. This fringe spacing depends upon the geometric configuration of the TEM/electron biprism system, which is experimentally fixed, but also upon the voltage applied to the biprism wire of the holography unit, which is experimentally adjustable. Hence, knowledge of the holographic interference fringe spacing as a function of applied voltage to the electron biprism is essential to the design of a specific holography experiment. Furthermore, additional instrumental parameters, such as the coherence and virtual size of the electron source, for example, affect the quality of recorded holograms through their effect on the contrast of the holographic fringes.


Microscopy ◽  
2020 ◽  
Vol 69 (6) ◽  
pp. 411-416
Author(s):  
Tetsuya Akashi ◽  
Yoshio Takahashi ◽  
Ken Harada

Abstract We have developed an amplitude-division type Mach-Zehnder electron interferometer (MZ-EI). The developed MZ-EI is composed of single crystals corresponding to amplitude-division beam splitters, lenses corresponding to mirrors and an objective aperture. The spacings and azimuth angles of interference fringes can be controlled by single crystal materials and their orientations and by diffraction spots selected by the objective aperture. We built the MZ-EI on a 1.2-MV field-emission transmission electron microscope and tested its performance. Results showed that interference fringes were created for various spacings and azimuth angles, which demonstrates the practicability of the MZ-EI as an amplitude-division type electron interferometer.


Microscopy ◽  
2020 ◽  
Author(s):  
Marek Malac ◽  
Simon Hettler ◽  
Misa Hayashida ◽  
Emi Kano ◽  
Ray F Egerton ◽  
...  

Abstract In this paper, we review the current state of phase plate imaging in a transmission electron microscope (TEM). We focus especially on the hole-free phase plate (HFPP) design, also referred to as the Volta phase plate (VPP). We discuss the implementation, operating principles and applications of phase plate imaging. We provide an imaging theory that accounts for inelastic scattering in both the sample and in the HFPP.


1994 ◽  
Vol 65 (20) ◽  
pp. 2553-2555 ◽  
Author(s):  
Takayuki Shibata ◽  
Atsushi Ono ◽  
Kenji Kurihara ◽  
Eiji Makino ◽  
Masayuki Ikeda

1998 ◽  
Vol 6 (9) ◽  
pp. 18-21
Author(s):  
Alwyn Eades

The world of electron microscopy is in a period of transition from acquiring images on film to acquiring images digitally, using CCD cameras, for example. It would be useful to knew how much information there is on a piece of film, in order to know how film compares with digital methods and to be able to make good judgements on the optimum moment to change from one technology to the other.This is an attempt to use simple arguments to estimate just how much information there is in an image exposed on film in the transmission electron microscope, the main reason for addressing this issue Is that, while many people are affected by it there seems to be little agreement on the answer.


2010 ◽  
Vol 16 (4) ◽  
pp. 434-440 ◽  
Author(s):  
Hannes Lichte ◽  
Martin Linck ◽  
Dorin Geiger ◽  
Michael Lehmann

AbstractElectron holography has been shown to allow a posteriori aberration correction. Therefore, an aberration corrector in the transmission electron microscope does not seem to be needed with electron holography to achieve atomic lateral resolution. However, to reach a signal resolution sufficient for detecting single light atoms and very small interatomic fields, the aberration corrector has turned out to be very helpful. The basic reason is the optimized use of the limited number of “coherent” electrons that are provided by the electron source, as described by the brightness. Finally, quantitative interpretation of atomic structures benefits from the holographic facilities of fine-tuning of the aberration coefficients a posteriori and from evaluating both amplitude and phase.


2001 ◽  
Vol 16 (9) ◽  
pp. 2550-2555 ◽  
Author(s):  
Junyong Kang ◽  
Tomoya Ogawa

Two types of threading dislocations with edge components were investigated by a high-resolution transmission electron microscope in undoped GaN epilayers grown on Al2O3 substrates. One is a fully filled core with regular contraction and stretch of bright dots, and the other is incompletely filled with one bright dot less and irregular contraction and stretch of bright dots. The bright dots were distorted and degenerated into bright line segments at cores in areas with smaller local dislocation intervals. The calculated results suggested that the distorted bright regions are attributable to the glide and/or climb caused by nearby dislocation interactions.


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