Microprocessor control of a field-emission scanning electron microscope (Model S-800)

1983 ◽  
Vol 41 ◽  
pp. 410-411
Author(s):  
S. Saito ◽  
Y. Nakaizumi ◽  
T. Nagatani ◽  
H. Todokoro
Keyword(s):  
Electron Microscope ◽  
Control System ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Operating Conditions ◽  
Gun Control ◽  
Electron Gun ◽  
Microprocessor Control ◽  
Emission Electron ◽  
Scanning Electron

We have developed an ultra high resolution scanning electron mícroscope utílízíng a fíeld emíssíon electron source (Fig.1). This instrument has a guaranteed resolution of 2 nm in the secondary electron image mode and it has incorporated a microprocessor control for optimized operating conditions and maximum ease of operation by various automated functions. The microprocessor control system includes field emission electron gun control, electron optical system control, and video signal control. The field emission electron gun control system includes flashing operation which is used to clean the tip surface by heating for a very short time, high voltage operation of accelerating voltage (V0) and tip voltage (V1), correction of emission current which changes with time, and correction of virtual source position which changes with a voltage ratio V0/V1. We have automated these series of operations by developing an auto FE gun control system. Fig. 2 shows details of this system.

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.

Development of 100 kV Field Emission Scanning Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 408-409
Author(s):  
H. Koike ◽  
Y. Harada ◽  
T. Goto ◽  
Y.Kokubo ◽  
K. Yamada ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Chemical Elements ◽  
Signal To Noise Ratio ◽  
Electron Gun ◽  
The Past ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Scanning Electron

During the past ten years, the resolution of the CTEM has been improved to a theoretical value determined by spherical and diffraction aberrations. In the scanning electron microscope, however, the resolution is restricted by the signal-to-noise ratio. Crewe et al were the first to increase the resolution by applying a field emission source to a 35 kV scanning electron microscope, resulting in a 5 Å resolution. Owing to its prominent brightness, the feild emission electron gun promises to increase not only the resolution of STEM images, but also to realize an analytical electron microscope which identifies chemical elements, crystalline structures and chemical bonding in specimen microareas in the order of less than 100 Å.

Low Acceleration Scanning Electron Microscope

1980 ◽  
Vol 38 ◽  
pp. 70-71
Author(s):  
H. Todokoro ◽  
S. Fukuhara ◽  
Y. Sakitani
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Secondary Electron Emission ◽  
High Sensitivity ◽  
Electron Gun ◽  
High Yield ◽  
List Type ◽  
Acceleration Voltage ◽  
Scanning Electron

A low acceleration scanning electron microscope ( LASEM ) offers several advantages: no charging effects low radiation damage high yield for secondary electron emission high sensitivity for surface topography The application of a low acceleration microscope, however, has been limited to special purposes because of its poor resolution. A high resolution LASEM has been developed and is shown in Fig.1. The microscope uses a new electron gun with a field emission cathode. The gun 1,000 times brighter than a conventional thermionic cathode. The relation between brightness and resolution of a SEM for 1 kV acceleration voltage is shown in Fig.2. The three regions in the figure correspond to tungsten thermionic, LaB6 thermionic and field emission guns. Resolution is approximately 1 μm in the case of the tungsten thermionic gun at 1 kV, while resolution is 200 A in the new microscope equipped with a field emission gun.

A Field Emission Scanning Electron Microscope Operating in the Secondary Electron Imaging Mode

1972 ◽  
Vol 30 ◽  
pp. 434-435
Author(s):  
T. Komoda ◽  
S. Saito ◽  
Y. Kakinuma ◽  
A. Okura
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Secondary Electron ◽  
Electron Gun ◽  
Emission Current ◽  
Electron Imaging Mode ◽  
Imaging Mode ◽  
Electron Imaging ◽  
Scanning Electron

The authors have built a surface scanning electron microscope incorporating a field emission electron gun. The gun has a brightness almost three order of magnitude higher than that of the ordinary thermionic electron gun, which is promissing high resolution in the secondary electron imaging mode.Emission current fluctuation, which is one of the most serious problems in field emission guns, depends on the vacuum condition around the field emission tip. In order to provide a good vacuum environment, the gun assembly in this microscope is located in the center of an ion-pump system which is symmetrically laid out relative to the electron optical axis. Two tips are mounted on a turret holder and they are exchangeable from the outside without disturbing the vacuum in the gun chamber. A stable emission current of the order of 10μA is obtainable at the normal vacuum operation better than 5x10-10 Torr.

The Materials Analysis Company Model 700 Scanning Electron Microscope

1968 ◽  
Vol 26 ◽  
pp. 370-371
Author(s):  
V.G. Macres ◽  
O. Preston ◽  
N.C. Yew ◽  
R. Buchanan
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Operating Conditions ◽  
Electron Gun ◽  
Objective Lens ◽  
Grid Spacing ◽  
Materials Analysis ◽  
Condenser Lens ◽  
Modular Concept ◽  
Scanning Electron

The Model 700 scanning electron microscope is a high resolution instrument which incorporates the same basic modular concept that has proven so satisfactory in the Materials Analysis Company Model 400 x-ray microprobe and its latest development, the Model 400S. The instrument described here is the basic building block to which accessories such as additional display tubes, special specimen holders, etc., can be easily added.The electron-optical column consists of a triode electron gun, double electromagnetic condenser lens, and objective lens. A .004″ tungsten hairpin filament is used as the electron source, and the filament to grid spacing is externally adjustable during operation to optimize gun performance for all operating conditions. The double condenser system is unitized and uses a single energizing coil. An adjustable multiple aperture holder is provided between the double condenser lens system and the objective lens, which serves to define the convergence angle of the probe in the specimen plane.

An Electron Gun Scanning Microscope

1968 ◽  
Vol 26 ◽  
pp. 360-361
Author(s):  
A. V. Crewe ◽  
D. Johnson ◽  
M. Isaacson
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Beam Current ◽  
Angular Spread ◽  
Electron Gun ◽  
Emission Current ◽  
Scanning Microscope ◽  
Schematic Drawing ◽  
Scanning Electron

A simple scanning electron microscope has been built using a field emission electron gun. The gun is used alone, without the aid of auxiliary lenses, and is theoretically capable of producing a 100 Å probe with a beam current of 10-10 A. Such a beam current allows scan times of the order of a few seconds.A schematic drawing of the microscope is shown in Fig. 2. The field emission voltage is applied to the first anode which controls the emission current. An accelerating voltage is applied to the second anode, and the field between the anodes focuses the electrons to form an image of the tip at the specimen. The angular spread of the beam is limited by an aperture on the second anode.

Field Emission SEM Equipped With Noise Compensator

1973 ◽  
Vol 31 ◽  
pp. 302-303
Author(s):  
S. Saito ◽  
H. Todokoro ◽  
S. Nomura ◽  
T. Komoda
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Low Contrast ◽  
Probe Current ◽  
High Resolution Images ◽  
Scanning Electron

Field emission scanning electron microscope (FESEM) features extremely high resolution images, and offers many valuable information. But, for a specimen which gives low contrast images, lateral stripes appear in images. These stripes are resulted from signal fluctuations caused by probe current noises. In order to obtain good images without stripes, the fluctuations should be less than 1%, especially for low contrast images. For this purpose, the authors realized a noise compensator, and applied this to the FESEM.Fig. 1 shows an outline of FESEM equipped with a noise compensator. Two apertures are provided gust under the field emission gun.

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.

Comparison of freeze-fractured yeast replicas using conventional TEM and low-voltage field-emission SEM

1989 ◽  
Vol 47 ◽  
pp. 74-75
Author(s):  
William P. Wergin ◽  
Eric F. Erbe ◽  
Terrence W. Reilly
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Low Voltage ◽  
Objective Lens ◽  
Specimen Preparation ◽  
Lens System ◽  
Air Drying ◽  
Preparation Techniques ◽  
Scanning Electron

Although the first commercial scanning electron microscope (SEM) was introduced in 1965, the limited resolution and the lack of preparation techniques initially confined biological observations to relatively low magnification images showing anatomical surface features of samples that withstood the artifacts associated with air drying. As the design of instrumentation improved and the techniques for specimen preparation developed, the SEM allowed biologists to gain additional insights not only on the external features of samples but on the internal structure of tissues as well. By 1985, the resolution of the conventional SEM had reached 3 - 5 nm; however most biological samples still required a conductive coating of 20 - 30 nm that prevented investigators from approaching the level of information that was available with various TEM techniques. Recently, a new SEM design combined a condenser-objective lens system with a field emission electron source.

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