Development of 350-KV holography electron microscope equipped with magnetic type field-emission electron gun

1989 ◽  
Vol 47 ◽  
pp. 104-105
Author(s):  
J. Endo ◽  
T. Kawasaki ◽  
T. Masuda ◽  
A. Tonomura
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
High Sensitivity ◽  
Beam Current ◽  
Electron Gun ◽  
Electron Holography ◽  
Electron Microscopic ◽  
Magnetic Lens ◽  
High Brightness ◽  
Emission Electron

A field-emission electron gun is one of the most epoch-making technologies in an electron microscopic world. In a transmission electron microscope, a high brightness of this beam has been effectively employed for electron-holographic measurements, though the value is not still high enough. Development of a higher brightness beam will promise to open up unattained application possibilities of electron holography such as high resolution and high sensitivity interferometry.We developed the field emission electron microscope for electron holographic applications. Special attentions were paid for high brightness, large beam current and easy operation. Figure 1 is a schematic diagram of the electron gun. In order not to deteriorate the original high-brightness feature of the beam by the aberrations in the gun and the condenser lenses, a magnetic lens was installed between the tip and the extraction anode so that the total aberration effect might be minimized. Field emitted electron beam is converged by the magnetic and the electrostatic lenses, and accelerated in a ten-stage accelerator which is made of porcelain.

Off-axis electron holography by field emission electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 224-225
Author(s):  
A. Tonomura ◽  
T. Matsuda ◽  
T. Komoda
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Electron Source ◽  
Electron Gun ◽  
Electron Holography ◽  
One Dimensional ◽  
Interference Fringes ◽  
Emission Electron ◽  
Electric Supply ◽  
Optical Laser

Although the feasibility of electron holography has been verified by several authors, it has not yet been put to practical use. This is because of the lack of a coherent electron source, such as optical laser. In practice, the number of interference fringes produced with a biprism is 200 at most, the exception being one dimensional cases. Off-axis holography requires 5,000∼100,000 interference fringes. Therefore, the useful application of electron holography in higher resolution and phase contrast electron microscopy hinges on development of a coherent electron source capable of producing 5,000 fringes or more.To realize a coherent electron source, a 100 kV field emission electron gun was developed and attached to an electron microscope. In designing the microscope,special care was taken in the column and electric supply. This was done to minimize movement of the small beam spot, which is easily disturbed from outside, so as to maintain the field emission electron beam.

Characteristics and Application of Temperature-Field Emitters

1975 ◽  
Vol 33 ◽  
pp. 144-145
Author(s):  
N. Tamura ◽  
T. Goto ◽  
Y. Harada
Keyword(s):  
Temperature Field ◽  
Electron Microscope ◽  
Field Emission ◽  
Resolving Power ◽  
High Brightness ◽  
Field Emitters ◽  
Emission Electron ◽  
Sufficient Stability ◽  
Scanning Electron ◽  
Illuminating System

On account of its high brightness, the field emission electron source has the advantage that it provides the conventional electron microscope with highly coherent illuminating system and that it directly improves the, resolving power of the scanning electron microscope. The present authors have reported some results obtained with a 100 kV field emission electron microscope.It has been proven, furthermore, that the tungsten emitter as a temperature field emission source can be utilized with a sufficient stability under a modest vacuum of 10-8 ~ 10-9 Torr. The present paper is concerned with an extension of our study on the characteristics of the temperature field emitters.

Performance and applications of the holography electron microscope

1993 ◽  
Vol 51 ◽  
pp. 1078-1079
Author(s):  
Akira Tonomura
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Phase Measurement ◽  
Electron Holography ◽  
Imaging Method ◽  
High Contrast ◽  
Magnetic Lens ◽  
High Brightness ◽  
Holographic Imaging ◽  
Dynamic Observation

Electron holography is a two-step imaging method. However, the ultimate performance of holographic imaging is mainly determined by the brightness of the electron beam used in the hologram-formation process. In our 350kV holography electron microscope (see Fig. 1), the decrease in the inherently high brightness of field-emitted electrons is minimized by superposing a magnetic lens in the gun, for a resulting value of 2 × 109 A/cm2 sr. This high brightness has lead to the following distinguished features. The minimum spacing (d) of carrier fringes is d = 0.09 Å, thus allowing a reconstructed image with a resolution, at least in principle, as high as 3d=0.3 Å. The precision in phase measurement can be as high as 2π/100, since the position of fringes can be known precisely from a high-contrast hologram formed under highly collimated illumination. Dynamic observation becomes possible because the current density is high.

A Field Emission Electron Microscope

1971 ◽  
Vol 29 ◽  
pp. 6-7
Author(s):  
A. Tonomura ◽  
T. Komoda
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
High Vacuum ◽  
High Resolution Electron Microscopy ◽  
Ultra High Vacuum ◽  
Electron Optics ◽  
Ion Pumps ◽  
High Brightness ◽  
Emission Electron ◽  
Resolution Electron

We have developed a field emission electron microscope. Although field emission gun requires ultra high vacuum and skillful technique, it brings about the favorable characteristics of high brightness and small energy spread. This characteristics will enable a significant progress in coherent electron optics and high resolution electron microscopy, especially in electron beam holography.Its column is Hitachi HU-11C Electron Microscope modified for ultra high vacuum operation, and it is evacuated with five ion pumps. Field emission gun is divided into two parts and is evacuated differentially with two ion pumps and a sublimation pump. The final pressures in these rooms are 5x10-10 Torr and 5x10-8 Torr respectively.

Development of A 350-KV Holography Electron Microscope and its Applications

1990 ◽  
Vol 48 (1) ◽  
pp. 222-223
Author(s):  
Takeshi Kawasaki ◽  
Junji Endo ◽  
Tsuyoshi Matsuda ◽  
Akira Tonomura
Keyword(s):  
Thin Film ◽  
Electron Beam ◽  
Electron Microscope ◽  
Field Emission ◽  
Source Image ◽  
Electron Holography ◽  
Magnetic Lens ◽  
Lattice Image ◽  
Gold Thin Film ◽  
Spacing Lattice

The 350 kV field-emission electron microscope shown in Fig.1 has been developed to widen the applications of electron holography. A field emission beam is used because it is very bright at first and monochromatic. However, its brightness deteriorates while passing through accelerating electrodes and condenser lenses because of their spherical and chromatic aberrations. A magnetic lens is installed just below a (310)-oriented tungsten tip. A magnetic lens is used so that the electron source image can be located at the most favorable position between the accelerating tube and the first condenser lens to minimize the aberrations and to increase brightness. The measured brightness (probe current) ranges from 1.4x109 A/cm2/sr (0.37 nA) to 6.7x108 A/cm2/sr (2.2 nA) with 10 μA total emission current at 300 kV.These increased brightness and narrow energy spread of the electron beam enable observing fine spacing lattice fringes in a gold thin film. Lattice fringes of 0.065 nm spacing were actually observed in the electron micrograph shown in Fig. 2. The incident electron beam was along the [001] axis, and the (400) and reflected beams were used to form the fringes. A 0.055 nm spacing lattice image is shown in Fig. 3. These fringes resulted from the interference of the electron beam, with an incident axis from the [111] direction into the gold thin film, by the and diffracted beams. This spacing is the shortest observed to date.

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

2000 ◽  
Vol 6 (S2) ◽  
pp. 1142-1143
Author(s):  
Takaho Yoshida ◽  
Takeshi Kawasaki ◽  
Junji Endo ◽  
Tadao Furutsu ◽  
Isao Matsui ◽  
...  
Keyword(s):  
Electron Beam ◽  
Field Emission ◽  
Optical Design ◽  
Electron Gun ◽  
Electron Holography ◽  
Optimized Design ◽  
Emission Electron ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Aharonov Bohm

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.

scholarly journals Electron Holography by Field Emission Electron Microscope

1980 ◽  
Vol 22 (3) ◽  
pp. 263-269 ◽  
Author(s):  
Akira TONOMURA ◽  
Tsuyoshi MATSUDA ◽  
Junji ENDO
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Electron Holography ◽  
Emission Electron

A Compact Field Emission Scanning Electron Microscope

1971 ◽  
Vol 29 ◽  
pp. 32-33 ◽  
Author(s):  
L. M. Welter ◽  
V. J. Coates
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Electron Gun ◽  
Readout System ◽  
Amplitude Control ◽  
Emission Electron ◽  
Compact Field ◽  
New Instrument ◽  
Scanning Electron

A compact field emission scanning electron microscope has been developed and modeled after the optical microscope. The new instrument consists of the field emission electron gun, an externally adjustable aperture strip containing four different hole sizes, an electromagnetic single deflection system, an electromagnetic stigmator with independent magnitude and amplitude control, an ion pumped specimen chamber, and a television readout system. No magnetic lenses are used.The field emission electron gun incorporates an electrode system which simultaneously accelerates and focuses the electrons drawn from a field emission source. Several improvements have been made in the basic gun to provide for higher tip stability and reliability. A unique pumping scheme has been incorporated in the gun to provide tip region pressures in the order of 10-9 Torr and below so that stable field emission can be routinely obtained.

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