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Development of a 1-MV Field-Emission Electron Microscope III. Electron Optical Design and Development of Field-Emission Electron Gun

Published online by Cambridge University Press:  02 July 2020

Takaho Yoshida
Affiliation:
Advanced Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama, 350-0395, Japan CREST, Japan Science and Technology Corporation
Takeshi Kawasaki
Affiliation:
Advanced Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama, 350-0395, Japan CREST, Japan Science and Technology Corporation
Junji Endo
Affiliation:
Advanced Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama, 350-0395, Japan
Tadao Furutsu
Affiliation:
Instruments, Hitachi, Ltd., 882 Ichige, Hitachi-naka, Ibaragi312-0033, Japan CREST, Japan Science and Technology Corporation
Isao Matsui
Affiliation:
Instruments, Hitachi, Ltd., 882 Ichige, Hitachi-naka, Ibaragi312-0033, Japan CREST, Japan Science and Technology Corporation
Tsuyoshi Matsuda
Affiliation:
Advanced Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama, 350-0395, Japan CREST, Japan Science and Technology Corporation
Nobuyuki Osakabe
Affiliation:
Advanced Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama, 350-0395, Japan CREST, Japan Science and Technology Corporation
Akira Tonomura
Affiliation:
Advanced Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama, 350-0395, Japan CREST, Japan Science and Technology Corporation
Koichi Kitazawa
Affiliation:
Department of Applied Chemistry, University of Tokyo, Hongo, Bunkyo, Tokyo, 113-8656, Japan CREST, Japan Science and Technology Corporation
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Extract

Bright and coherent electron beams have been opening new frontiers in science and technology. So far, we have developed several field-emission transmission electron microscopes (FE-TEM) with increasing accelerating voltages to provide higher beam brightness. By using a 200-kV FE-TEM and electron holography techniques, we directly confirmed the Aharonov-Bohm effect. A 350-kV FE-TEM equipped with a low-temperature specimen stage enabled us to observe moving vortices in superconductors.2 Most Recently, we have developed a new 1-MV FE-TEM with a newly designed FE gun to obtain an even brighter and more coherent electron beam.

Electron beam brightness, Br, defined in Figure 1, is suitable for measuring the performance of electron guns, since both lens aberrations and mechanical/electrical vibrations contribute to a decrease in beam brightness, and beam coherency is proportional to (Br)1/2. Therefore, we optimized design of the illuminating system and its operation by maximizing the electron beam brightness.

Type
Instrument Performance
Copyright
Copyright © Microscopy Society of America

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References

References:

1)Osakabe, N. et al. Phys. Rev. A, 34 (1986) 815CrossRefGoogle Scholar
2 )Tonomura, A. et al. Nature, 397 (1999) 308CrossRefGoogle Scholar
3 )Kawasaki, T. et al. Microbeam Analysis, 3 (1994) 287Google Scholar
4 )Kawasaki, T. et al. APL, 76 (2000) (in press)Google Scholar