Condenser Lens Evaluation Using the Null-Screens Test

2017 ◽  
Author(s):  
Daniel Aguirre-Aguirre ◽  
Rufino Díaz-Uribe ◽  
Brenda Villalobos-Mendoza ◽  
Manuel Campos-Garcia
Keyword(s):  
Condenser Lens

Description of a New High Resolution Scanning Transmission EM

1972 ◽  
Vol 30 ◽  
pp. 418-419
Author(s):  
Michael Beer ◽  
J. W. Wiggins ◽  
David Woodruff ◽  
Jon Zubin
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Energy Dispersive Spectrometer ◽  
Scanning Transmission Electron Microscope ◽  
Objective Lens ◽  
Condenser Lens ◽  
Transmission Electron ◽  
Pattern Size ◽  
Scanning Transmission ◽  
Under Construction

A high resolution scanning transmission electron microscope of the type developed by A. V. Crewe is under construction in this laboratory. The basic design is completed and construction is under way with completion expected by the end of this year.The optical column of the microscope will consist of a field emission electron source, an accelerating lens, condenser lens, objective lens, diffraction lens, an energy dispersive spectrometer, and three electron detectors. For any accelerating voltage the condenser lens function to provide a parallel beam at the entrance of the objective lens. The diffraction lens is weak and its current will be controlled by the objective lens current to give an electron diffraction pattern size which is independent of small changes in the objective lens current made to achieve focus at the specimen. The objective lens demagnifies the image of the field emission source so that its Gaussian size is small compared to the aberration limit.

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.

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.

Development of Multi-Purpose Thermal Field Emission SEM

2001 ◽  
Vol 7 (S2) ◽  
pp. 876-877
Author(s):  
M. Mita ◽  
T. Nokuo ◽  
T. Yanagihara ◽  
K. Ogura ◽  
M. Iwatsuki ◽  
...  
Keyword(s):  
Field Emission ◽  
Thermal Field ◽  
Ebsd Analysis ◽  
Objective Lens ◽  
Electron Optics ◽  
Condenser Lens ◽  
Probe Current ◽  
The Past ◽  
The Magnetic Field ◽  
Immersion Type

Past FE-SEM could obtain a high resolution image, however its probe current was not sufficiently strong enough for analytical purpose.We have developed a multi-purpose thermal field emission scanning electron microscope (JSM- 6500F), in which a new designed “In-Lens Thermal FEG” is installed.Fig. 1 shows a cross section images of the In-Lens Thermal FEG, comparing with the past FEG. The In-Lens Thermal FEG consists of the thermal FEG and the 1st condenser lens. The emitter is located in the magnetic field produced by the 1st condenser lens, so that electrons emitted from the emitter are condensed effectively to produced a high probe current. The maximum probe current of 200 nA is attainable at the accelerating voltage of 15 kV, ten times larger than the maximum probe current of ordinary FE-SEMs. Therefore the WDS analysis can be performed by this newly FE-SEM.The “aperture angle control lens” has been installed in the electron optics system, for improving the resolution at a large probe current. The resolution of 3.0nm at the analytical condition (at probe current 5nA, accelerating voltage 15kV, WD 10mm: fig.2).The ultimate resolution of the microscope is 1.5nm at 15kV and 5nm at lkV. The objective lens is not an immersion type and does not leak magnetic fields on the specimen surface, therefore this equipment was suitable for observing or analyzing magnetic materials, and also suitable for the EBSD analysis. Fig.3 shows an example of the EBSD analysis.

Using the TEM Condenser Lens to Switch between Image and Diffraction Modes

2013 ◽  
Vol 21 (2) ◽  
pp. 40-40
Author(s):  
Lydia Rivaud
Keyword(s):  
Electron Microscope ◽  
Diffraction Pattern ◽  
Transmission Electron Microscope ◽  
Condenser Lens ◽  
Selected Area Diffraction Pattern ◽  
Transmission Electron ◽  
Set Up ◽  
Convergent Beam ◽  
Beam Diffraction ◽  
Convergent Beam Diffraction

Central to the operation of the transmission electron microscope (TEM) (when used with crystalline samples) is the ability to go back and forth between an image and a diffraction pattern. Although it is quite simple to go from the image to a convergent-beam diffraction pattern or from an image to a selected-area diffraction pattern (and back), I have found it useful to be able to go between image and diffraction pattern even more quickly. In the method described, once the microscope is set up, it is possible to go from image to diffraction pattern and back by turning just one knob. This makes many operations on the microscope much more convenient. It should be made clear that, in this method, neither the image nor the diffraction pattern is “ideal” (details below), but both are good enough for many necessary procedures.

Application of the condenser lens in microwave hyperthermia

2010 ◽  
Vol 54 (1) ◽  
pp. 237-243
Author(s):  
Bing Sun ◽  
GuoTai Jiang ◽  
ZhiHong Chen ◽  
Li Wang
Keyword(s):  
Condenser Lens ◽  
Microwave Hyperthermia

A 100 KV Transmission Scanning Microscope

1971 ◽  
Vol 29 ◽  
pp. 22-23
Author(s):  
A. V. Crewe
Keyword(s):  
Focal Length ◽  
Electron Gun ◽  
Objective Lens ◽  
Scanning Microscope ◽  
Parallel Beam ◽  
Condenser Lens ◽  
Focal Length Lens ◽  
Short Focal Length ◽  
Pass Through ◽  
Correction System

A 100 kv transmission scanning microscope is now being constructed which should have a point resolution of 2.5 to 3 Å. The design of this microscope is similar to the design of our existing 30 kv 5 Å microscope, but there are several significant changes which are based upon some difficulties and sources of inflexibility of that microscope.A field emission electron gun of our usual design will be used as the source of electrons, the only difference being that the spacing between the anodes has been increased from 2 to 3 cm. The electron beam will then pass through a condenser lens which will produce a parallel beam of electrons. This parallel beam will then be focused onto the specimen by means of a short focal length lens (approximately 1 mm focal length). The reason for using a condenser lens to produce the parallel beam of electrons is that in the future a quadrupole-octupole correction system will be installed in this section of the microscope in order to attempt to correct the spherical aberrations of the objective lens and thereby improve its resolution.

A Combined Scanning Electron Microscope/Electron Microprobe Analyzer

1968 ◽  
Vol 26 ◽  
pp. 368-369
Author(s):  
V.G. Macres ◽  
O. Preston ◽  
N.C. Yew ◽  
R. Buchanan
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Electron Microprobe ◽  
High Performance ◽  
Electron Gun ◽  
Objective Lens ◽  
Condenser Lens ◽  
X Ray ◽  
Low X ◽  
Scanning Electron

The instrument described here is the Materials Analysis Company Model 400S combined scanning electron microscope/electron micro-probe analyzer. It was designed specifically to incorporate the most advanced features of a high performance electron microprobe analyzer with those of a medium resolution (1000A°) scanning electron microscope. The high effective x-ray take-off angle of the instrument (38.5°) offers low x-ray absorption, and thus allows the analysis of fairly rough specimens. The large depth of focus of the scanned electron images further enhances the capability of examining rough specimens.The electron-optical column comprises a triode electron gun, double condenser lens and objective lens. The electron gun uses a conventional hairpin filament, autobiased Wehnelt cylinder and anode. An externally controlled filament/Wehnelt cylinder height adjustment is provided for optimizing gun performance at all operating potentials. The double condenser lens is unitized and has two lens regions and a common energizing coil.

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