A New High Intensity Grid Cap for RCA-EMU-3 Electron Microscopes

1968 ◽  
Vol 26 ◽  
pp. 316-317
Author(s):  
George Christov ◽  
Bolivar J. Lloyd
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Voltage ◽  
High Intensity ◽  
Electron Gun ◽  
Tungsten Filament ◽  
Fluorescent Screen ◽  
Electron Microscopes ◽  
Pass Through ◽  
Ground Potential

A new high intensity grid cap has been designed for the RCA-EMU-3 electron microscope. Various parameters of the new grid cap were investigated to determine its characteristics. The increase in illumination produced provides ease of focusing on the fluorescent screen at magnifications from 1500 to 50,000 times using an accelerating voltage of 50 KV.The EMU-3 type electron gun assembly consists of a V-shaped tungsten filament for a cathode with a thin metal threaded cathode shield and an anode with a central aperture to permit the beam to course the length of the column. The cathode shield is negatively biased at a potential of several hundred volts with respect to the filament. The electron beam is formed by electrons emitted from the tip of the filament which pass through an aperture of 0.1 inch diameter in the cap and then it is accelerated by the negative high voltage through a 0.625 inch diameter aperture in the anode which is at ground potential.

Electron Accelerators for High-Voltage Electron Microscopy (HVEM)

1972 ◽  
Vol 30 ◽  
pp. 462-463
Author(s):  
Günter O. Reinhold
Keyword(s):  
Electron Beam ◽  
High Voltage ◽  
High Energy ◽  
Electron Gun ◽  
Resolving Power ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Electron Microscopes ◽  
The Stability

High-voltage electron microscopes are characterized by accelerating voltages in the megavolt range (500 kV and above). Compared to conventional electron microscopes, with voltages up to 200 kV, the high-voltage instruments offer the advantage of improved resolving power (1 to 10 Å) and greater effective penetration of the electron beam. A basic difference between ordinary and high-voltage electron microscopes is the use of an electron accelerator in place of the electron gun to accelerate the electron beam to the required high energy. The resolving power of an electron microscope is determined by the stability of the accelerating voltage, the mechanical precision of the lenses and specimen stages, the stability of the lens supply current and freedom from mechanical vibrations. The symmetrical cascade generator is the only high-voltage dc power supply to meet these requirements with regard to voltage stability and vibration-free performance.

The Reduction of Chromatic Aberrations Due to Instrumental Instabilities

1971 ◽  
Vol 29 ◽  
pp. 14-15
Author(s):  
J. S. Lally ◽  
R. Evans
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Usual Practice ◽  
Voltage Electron ◽  
Short Focal Length ◽  
Chromatic Aberrations ◽  
Electron Microscopes

One of the instrumental factors often limiting the resolution of the electron microscope is image defocussing due to changes in accelerating voltage or objective lens current. This factor is particularly important in high voltage electron microscopes both because of the higher voltages and lens currents required but also because of the inherently longer focal lengths, i.e. 6 mm in contrast to 1.5-2.2 mm for modern short focal length objectives.The usual practice in commercial electron microscopes is to design separately stabilized accelerating voltage and lens supplies. In this case chromatic aberration in the image is caused by the random and independent fluctuations of both the high voltage and objective lens current.

Modification of the Electron Microscope for Investigation of Fully Hydrated Biological Specimens

1969 ◽  
Vol 27 ◽  
pp. 418-419 ◽  
Author(s):  
R. C. Moretz ◽  
D. F. Parsons
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Structural Damage ◽  
Lower Percentage ◽  
Vacuum Drying ◽  
Total Removal ◽  
Total Absence ◽  
Biological Studies ◽  
Electron Microscopes ◽  
Beam Damage

Short lifetime or total absence of electron diffraction of ordered biological specimens is an indication that the specimen undergoes extensive molecular structural damage in the electron microscope. The specimen damage is due to the interaction of the electron beam (40-100 kV) with the specimen and the total removal of water from the structure by vacuum drying. The lower percentage of inelastic scattering at 1 MeV makes it possible to minimize the beam damage to the specimen. The elimination of vacuum drying by modification of the electron microscope is expected to allow more meaningful investigations of biological specimens at 100 kV until 1 MeV electron microscopes become more readily available. One modification, two-film microchambers, has been explored for both biological and non-biological studies.

Remote On-Line Control of a High-Voltage in situ Transmission Electron Microscope with A Rational User Interface

1996 ◽  
Vol 54 ◽  
pp. 384-385
Author(s):  
M.A. O’Keefe ◽  
J. Taylor ◽  
D. Owen ◽  
B. Crowley ◽  
K.H. Westmacott ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
User Interface ◽  
Transmission Electron Microscope ◽  
High Voltage ◽  
Materials Science ◽  
Transmission Electron ◽  
On Line ◽  
Electron Microscopes

Remote on-line electron microscopy is rapidly becoming more available as improvements continue to be developed in the software and hardware of interfaces and networks. Scanning electron microscopes have been driven remotely across both wide and local area networks. Initial implementations with transmission electron microscopes have targeted unique facilities like an advanced analytical electron microscope, a biological 3-D IVEM and a HVEM capable of in situ materials science applications. As implementations of on-line transmission electron microscopy become more widespread, it is essential that suitable standards be developed and followed. Two such standards have been proposed for a high-level protocol language for on-line access, and we have proposed a rational graphical user interface. The user interface we present here is based on experience gained with a full-function materials science application providing users of the National Center for Electron Microscopy with remote on-line access to a 1.5MeV Kratos EM-1500 in situ high-voltage transmission electron microscope via existing wide area networks. We have developed and implemented, and are continuing to refine, a set of tools, protocols, and interfaces to run the Kratos EM-1500 on-line for collaborative research. Computer tools for capturing and manipulating real-time video signals are integrated into a standardized user interface that may be used for remote access to any transmission electron microscope equipped with a suitable control computer.

scholarly journals Diagnostic Electron Microscopy of Viruses With Low-voltage Electron Microscopes

2020 ◽  
Vol 68 (6) ◽  
pp. 389-402
Author(s):  
Lars Möller ◽  
Gudrun Holland ◽  
Michael Laue
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Voltage ◽  
Low Voltage ◽  
Optical Resolution ◽  
Plant Diseases ◽  
Voltage Electron ◽  
Transmission Electron ◽  
High Voltage Transmission ◽  
Electron Microscopes

Diagnostic electron microscopy is a useful technique for the identification of viruses associated with human, animal, or plant diseases. The size of virus structures requires a high optical resolution (i.e., about 1 nm), which, for a long time, was only provided by transmission electron microscopes operated at 60 kV and above. During the last decade, low-voltage electron microscopy has been improved and potentially provides an alternative to the use of high-voltage electron microscopy for diagnostic electron microscopy of viruses. Therefore, we have compared the imaging capabilities of three low-voltage electron microscopes, a scanning electron microscope equipped with a scanning transmission detector and two low-voltage transmission electron microscopes, operated at 25 kV, with the imaging capabilities of a high-voltage transmission electron microscope using different viruses in samples prepared by negative staining and ultrathin sectioning. All of the microscopes provided sufficient optical resolution for a recognition of the viruses tested. In ultrathin sections, ultrastructural details of virus genesis could be revealed. Speed of imaging was fast enough to allow rapid screening of diagnostic samples at a reasonable throughput. In summary, the results suggest that low-voltage microscopes are a suitable alternative to high-voltage transmission electron microscopes for diagnostic electron microscopy of viruses.

scholarly journals FEI Titan 80-300 STEM

2016 ◽  
Vol 2 ◽  
Author(s):  
Marc Heggen ◽  
Martina Luysberg ◽  
Karsten Tillmann
Keyword(s):  
Electron Microscope ◽  
Scanning Transmission Electron Microscope ◽  
Electron Gun ◽  
Lens System ◽  
Scanning Transmission Electron ◽  
System A ◽  
Transmission Electron ◽  
The World ◽  
Scanning Transmission ◽  
Electron Microscopes

The FEI Titan 80-300 STEM is a scanning transmission electron microscope equipped with a field emission electron gun, a three-condenser lens system, a monochromator unit, and a Cs probe corrector (CEOS), a post-column energy filter system (Gatan Tridiem 865 ER) as well as a Gatan 2k slow scan CCD system. Characterised by a STEM resolution of 80 pm at 300 kV, the instrument was one of the first of a small number of sub-ångström resolution scanning transmission electron microscopes in the world when commissioned in 2006.

Microscopy of whole cells in ice

1991 ◽  
Vol 49 ◽  
pp. 428-429
Author(s):  
E.T. O'Toole ◽  
J.R. Mcintosh
Keyword(s):  
Electron Beam ◽  
Critical Point ◽  
High Voltage ◽  
Biological Material ◽  
Comparative Method ◽  
Native State ◽  
Whole Cells ◽  
The Past ◽  
Voltage Electron ◽  
Electron Microscopes

Cryomicroscopy of frozen hydrated specimens makes it possible to visualize biological material in a condition that is close to its native state by avoiding chemical fixatives, dehydration or stain. In the past, cryoimaging using a conventional TEM has been limited to thin frozen suspensions of biological material or to thin cryosections of frozen cells and tissues. High voltage electron microscopes (HVEM) offer the advantage of improved penetration of thick samples by the electron beam and thus are suitable for imaging thick frozen samples. Here we describe a comparative method for studying the ultrastructure of freeze substituted, critical point dried cells and frozen hydratpd cells in the HVEM.

A side-entry high-precision tilt stage for a high-voltage Electron Microscope

1986 ◽  
Vol 44 ◽  
pp. 628-629
Author(s):  
J.N. Turner ◽  
D.P. Barnard ◽  
G. Matuszek ◽  
C.W. See
Keyword(s):  
Electron Microscope ◽  
High Precision ◽  
High Voltage ◽  
Three Dimensional ◽  
Three Dimensional Reconstruction ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Dimensional Reconstruction ◽  
Electron Microscopes

A high precision specimen stage is essential for the accurate recording of images for three-dimensional reconstruction. The efficient calculation and resolution of a “tomographic type” three-dimensional reconstruction is influenced by the precision of the angular tilt settings. The ability to identify structures at low magnification and later return to them for detailed study at high magnification is crucial to the efficient study of structures by serial section reconstruction, and is greatly aided by a precise, repeatable translation stage. To study such problems, we have designed and fabricated a single-tilt specimen stage for our high-voltage electron microscope (HVEM), which represents a different design philosophy to that usually employed in side entry stages for transmission electron microscopes.

Development of Field-Emission Gun for High-Voltage Electron Microscope

1990 ◽  
Vol 48 (2) ◽  
pp. 94-95
Author(s):  
T. Tomita ◽  
S. Katoh ◽  
H. Kitajima ◽  
Y. Kokubo ◽  
Y. Ishida
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Field Emission ◽  
High Voltage ◽  
High Vacuum ◽  
Electron Gun ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Acceleration Tube

It is well known that the combination of a field emission gun (FEG) and a conventional transmission electron microscope (CTEM) is extremely important for nanometer area analysis in analytical electron microscopy. However, the smaller illumination angle and reduced energy spread of FEG than those of a conventional electron gun (W hair pin filament or LaB6) give a slowly damping envelop function in phase contrast transfer function (PCTF). Thus the FEG ensures application not only to analytical microscopy but also to high resolution electron microscopy to improve the information limit.In a high voltage electron microscope (above 200 kV), high-speed vacuum pumps have to be provided below the acceleration tube to get an ultra high vacuum (UHV) around the field emission tip located at the top of the acceleration tube. However, this method is not always the best way to provide UHV because of the poor vacuum conductance caused by the electrodes inside the acceleration tube.

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