scholarly journals Magnetic Field Mapping using Off-Axis Electron Holography in the Transmission Electron Microscope

Author(s):  
Fengshan Zheng ◽  
András Kovács ◽  
Thibaud Denneulin ◽  
Jan Caron ◽  
Teresa Weßels ◽  
...  
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.


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.


2005 ◽  
Vol 475-479 ◽  
pp. 4029-4034 ◽  
Author(s):  
Katsuhiro Sasaki ◽  
Hiroyasu Saka

A novel method to observe the electrostatic field distribution with a conventional transmission electron microscope has been developed. The method allows measurements of a potential difference less than 1V/µm. This method can be performed in any kind of conventional transmission electron microscope and applied to the observation of the electric/magnetic field at the level of a specimen.


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.


1994 ◽  
Vol 332 ◽  
Author(s):  
J.C.H. Spence ◽  
W. Qian ◽  
W. Lo ◽  
S. Mo ◽  
U. Knipping ◽  
...  

ABSTRACTThe design of a low voltage point-projection field-emission transmission electron microscope is described and images showing 0.7nm resolution at 100 volts are given. A scheme for low voltage reflection electron holography from bulk samples in UHV is outlined. A new STM is described which allows atomic clusters to be transferred onto the tip, then introduced into a time-of-flight analyser for species identification.


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