Optical characteristics of the hitachi HF-2000 cold field-emission TEM

1993 ◽  
Vol 51 ◽  
pp. 1076-1077
Author(s):  
L. F. Allard ◽  
E. Völkl ◽  
T. A. Nolan
Keyword(s):  
Field Emission ◽  
Recent Literature ◽  
Electron Gun ◽  
High Brightness ◽  
Condenser Lens ◽  
Illumination System ◽  
High Resolution Images ◽  
Imaging Mode ◽  
Better Than ◽  
Illuminating System

The illumination system of the cold field emission (CFE) Hitachi HF-2000 TEM operates with a single condenser lens in normal imaging mode, and with a second condenser lens excited to give the ultra-fine 1 nm probe for microanalysis. The electron gun provides a guaranteed high brightness of better than 7×l08 A/cm2/sr, more than twice the guaranteed brightness of Schottky emission guns. There have been several articles in the recent literature (e.g. refs.) which claim that the geometry of this illumination system yields a total current which is so low that when the beam is spread at low magnifications (say 10 kX), the operator must “keep his eyes glued to the binoculars” in order to see the image. It is also claimed that this illuminating system produces an isoplanatic patch (the area over which image character does not vary significantly) at high magnification which is so small that the instrument is ineffective for recording high resolution images.

Interference Experiments with a Field Emission Source

1970 ◽  
Vol 28 ◽  
pp. 534-535
Author(s):  
A. V. Crewe ◽  
J. Saxon
Keyword(s):  
Field Emission ◽  
Spherical Aberration ◽  
Electron Gun ◽  
Partial Coherence ◽  
Vacuum System ◽  
High Brightness ◽  
Small Spot ◽  
Tungsten Tip ◽  
Effective Source ◽  
Better Than

Field emission from a tungsten tip provides a source with very high brightness and high partial coherence. An electron gun of low spherical aberration is used to focus the electrons from the tip to a small spot about 100 Å in diameter. Since the voltages applied to the tip and gun are stable to better than 5 ppm, the temporal coherence is limited by the energy spread of the source, about 200 mv.Using the focused spot a few centimeters below the gun as an effective source, a metalized quartz fiber about 2 μ in diameter is positioned a few centimeters below the source, as shown in Fig. 1. Two cylindrica11y symmetric magnetic lenses are used to magnify the resulting Fresnel diffraction pattern. The image is produced on a fluorescent coating deposited on the vacuum side of a fiber optic window. The image is recorded directly on film placed against the window outside the vacuum system.

High Brightness Electron Gun Using a Field Emission Cathode

1968 ◽  
Vol 26 ◽  
pp. 294-295
Author(s):  
A. N. Broers
Keyword(s):  
Field Emission ◽  
Electron Gun ◽  
Field Emission Cathode ◽  
High Brightness ◽  
Probe Size ◽  
Test Grid ◽  
Two Stages ◽  
Emission Cathode ◽  
Scanning Electron ◽  
Better Than

A field emission cathode electron gun with two stages of acceleration has been built in order to measure the electron beam brightness that can be produced in practice from a tungsten field emission cathode. The gun is similar to that reported by A. Crewe except that the accelerating electrodes are plane, rather than shaped, apertures, and the cathode is located by a gimbal mechanism which allows the cathode to be tilted over an arc of 70° in any direction and positioned laterally. The gun electrodes have been precisely machined with the apertures round within 0.25 micron and aligned with respect to each other to better than 10 micron. The second accelerating electrode is followed by scan plates, a test grid, and an electron detector which together allow the probe size to be measured in the usual scanning electron microscope mode.

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.

A comparative study on the cold type and thermal type field emission guns used in the same electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 58-59
Author(s):  
M. Iwatsuki ◽  
Y. Kokubo ◽  
Y. Harada
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Signal To Noise Ratio ◽  
Electron Source ◽  
Resolving Power ◽  
Optical Source ◽  
Experimental Conditions ◽  
High Brightness ◽  
Illumination System ◽  
Transmission Electron

On accout of its high brightness, small optical source size, and minimal energy spread, the field emission gun (FEG) has the advantage that it provides the conventional transmission electron microscope (TEM) with a highly coherent illumination system and directly improves the resolving power and signal-to-noise ratio of the scanning electron microscope (SEM). The FEG is generally classified into two types; the cold field emission (C-FEG) and thermal field emission gun (T-FEG). The former, in which a field emitter is used at the room temperature, was successfully developed as an electron source for the SEM. The latter, in which the emitter is heated to the temperature range of 1000-1800°K, was also proved to be very suited as an electron source for the TEM, as well as for the SEM. Some characteristics of the two types of the FEG have been studied and reported by many authors. However, the results of the respective types have been obtained separately under different experimental conditions.

A Newly Designed 650kv Electron Microscope

1968 ◽  
Vol 26 ◽  
pp. 304-305
Author(s):  
K. Shiraishi ◽  
T. Katsuta ◽  
S. Ozasa ◽  
H. Todokoro
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Bright Field Image ◽  
Bright Field ◽  
Push Button ◽  
Condenser Lens ◽  
High Voltage Generator ◽  
Frequency Power ◽  
Better Than ◽  
Illuminating System

We have recently completed a newly designed 650KV electron microscope. An external view of this advanced instrument is shown in Figure 1. A symmetrical Cockcroft-Walton circuit has been adopted as the high voltage generator. The cathode is heated by high frequency power; a battery is not employed. The high voltage stability is better than 1 x 10-5/min.The sectional diagram of the column shown in Figure 2 is 420mm in diameter and 2750mm in height. The illuminating system consists of a double condenser lens and a magnetic alignment device. Dual deflector assemblies for dark and bright field images, selectable by push button, are built beneath the condenser lens. Two selectable stigmator power supplies are also provided for dark and bright field image operation.

An Illuminating System of a 100-kV Analytical Electron Microscope with a Field-Emission Electron Gun

1990 ◽  
Vol 48 (1) ◽  
pp. 122-123
Author(s):  
A. Delong ◽  
J. Chmelík ◽  
V. Kolařík
Keyword(s):  
Electron Microscopy ◽  
Field Emission ◽  
Analytical Electron Microscopy ◽  
Electron Gun ◽  
Transmission Mode ◽  
Resolving Power ◽  
Objective Lens ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Illuminating System

Our aim was to design a microscope for application in both the classical transmission electron microscopy (CTEM) and in the analytical electron microscopy having in the scanning modes (SEM, STEM) a resolving power approaching that in the CTEM. The problem can be optimally solved by using the field emission source of electrons. The illuminating system and the objective lens have the following parameters:a) The resolving power of the objective lens in the transmission mode is as high as 3.5 Å.b) The optical aberrations of the pre—field of the objective lens and of the set of condenser lenses allow a resolution of approx. 5 Å to be achieved in the scanning mode.c) The illuminated area of the specimen observed in the transmission mode is large enough to allow operation with the objective lens switched on at a magnification 1000 x.

Single-Crystal LaB6 as Thermal Field Emitter for Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 196-197
Author(s):  
Ken Harada ◽  
Haruto Nagata ◽  
Ryuichi Shimizu ◽  
Takayoshi Tanji ◽  
Keiji Yada
Keyword(s):  
Electron Microscope ◽  
Single Crystal ◽  
Field Emission ◽  
Thermal Field ◽  
Thermionic Emission ◽  
Electron Gun ◽  
Field Evaporation ◽  
Good Reproducibility ◽  
High Brightness ◽  
Evaporation Technique

Thermal field emission (T.F.E.) properties of single crystal LaB6 -tips has been investigated by observing emission patterns. Applying field evaporation technique we succeeded to get the clean pattern consisting of <310> spots with very good reproducibility. This investigation has led to conclusion;, the <310> spot is promising electron source of high brightness provided that the tip is operated at tip temperature∽ 1000-1050°C in vacuum of 10−9 Torr region.As a preliminary experiment of brightness-measurement, we mounted the <310> LaB6-tip in a commercial type TEM, JEM-100CX-FEG, attached with an electron gun system for T.F.E. of <100> W-tip, being operated at 10−9 Torr region without Schottky shield electrode. The LaB6-tip, however, can not be operated without the Schottky shield because thermionic emission (T.E.) from the LaB6-tip is considerably high even though the tip is operated at lower than ∽1000 °C. In the present experiment, therefore, we manufactured a Schottky shield electrode as shown in Fig.l and performed the measurement of brightness by setting the Schottky shield electrode, applied the same voltage as the tip since the electron gun system has no extra feed-throughs for bias-voltage.

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.

Interference Experiments with a Field Emission Electron Miscroscope

1974 ◽  
Vol 32 ◽  
pp. 386-387
Author(s):  
J. Munch ◽  
E. Zeitler
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Design Principles ◽  
Electron Gun ◽  
University Of Chicago ◽  
Emission Electron ◽  
The University ◽  
Better Than

We have modified a Hitachi HU 12 electron microscope by replacing the thermionic electron gun with a field emission gun. The design principles of this gun are substantially the same as those used in the scanning microscopes developed at the University of Chicago by A. V. Crewe and his collaborators. To accommodate the field emission gun in the conventional column two differentially pumped stages were employed, assuring a vacuum of better than 2 x 10−10 Torr in the tip region.

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