IMPROVED POLE PIECE CONSTRUCTION OF THE OBJECTIVE LENS OF A MAGNETIC ELECTRON MICROSCOPE

1940 ◽  
Vol 18a (11) ◽  
pp. 175-177 ◽  
Author(s):  
Albert Prebus
Keyword(s):  
Electron Microscope ◽  
Objective Lens ◽  
Pole Piece ◽  
University Of Toronto ◽  
New Form ◽  
The University ◽  
Magnetic Electron

The paper is a description of a new form of pole piece devised for the electron microscope developed at the University of Toronto.

Modification of a TEM for ultra-high-vacuum reflection-EM (UHV-REM) applications

1995 ◽  
Vol 53 ◽  
pp. 582-583
Author(s):  
Tung Hsu ◽  
Min-Yi Shih ◽  
A. V. Latyshev
Keyword(s):  
Electron Microscope ◽  
High Vacuum ◽  
High Energy ◽  
Ultra High Vacuum ◽  
Objective Lens ◽  
Pole Piece ◽  
High Energy Electron ◽  
Normal Position ◽  
Crystal Surfaces ◽  
Specimen Holder

A JEOL JEM-100C electron microscope was modified by adding a cryogenic UHV specimen holder for studying clean crystal surfaces with the reflection high energy electron diffraction (RHEED) and REM techniques. The Si(111) (l×l) and (7×7) phase transitions have been successfully observed (Fig. 1). Further modification is in progress for better resolution and other functions. Fig. 2.a shows the unmodified specimen holder and the objective lens of the microscope. The cryogenic holder based on the Novosibirsk design is shown in Fig. 2.b. Liquid nitrogen is continuously pumped through the shell of the holder for achieving UHV inside. The tilt/rotation controls and the current for heating of the specimen are fed through the holder. In this modification, the specimen was not placed at the normal position of the lens and therefore is not at the best position for imaging and diffraction.A new holder is shown in Fig. 2.c. This holder is inserted into the pole piece to place the specimen at the normal position.

Objective-lens design for high resolution ultra high vacuum EM

1992 ◽  
Vol 50 (1) ◽  
pp. 292-293
Author(s):  
Arno J. Bleeker ◽  
J. Murray Gibson
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Free Space ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Objective Lens ◽  
Auxiliary Equipment ◽  
Physical Experiments ◽  
Under Construction ◽  
The University

Although the main use for Transmission electron microscopy is to study bulk phenomena it is also possible to do surface sensitive experiments with this type of instrument. In order to do reliable surface physical experiments it is necessary to improve the vacuum within the vicinity of the specimen to the Ultra High Vacuum (UHV) level. A number of authors report on such improvements. In most designs the experiments with the sample such as deposition and oxidation are done outside the main microscope column. This means that it is not possible to observe the sample under high resolution conditions during these experiments. The importance of the electron microscope as a surface sensitive instrument can be greatly enhanced if it would be possible to do surface physical experiments in-situ. In that way it would become possible to observe the specimen with high resolution during all kinds of surface processes. In order to be able to do these experiments there must exist a large free space around the sample. In this free space auxiliary equipment such as ion guns and MBE cells can be placed. To further enhance the capabilities of the instrument, analyzing tools such as an Auger spectrometer and SIMS equipment can be attached to the microscope. At the University of Illinois an electron microscope capable of imaging the sample during surface physical experiments is presently under construction. In this machine the objective lens section has been replaced by a large (800 mm diameter and 400 mm high) UHV chamber. The specimen is outside the magnetic field of the objective lens in order to obtain as much free space around the sample as possible thus sacrificing resolution.

An environmental cell Transmission Electron Microscope

1990 ◽  
Vol 48 (4) ◽  
pp. 552-553
Author(s):  
D.K. Dewald ◽  
T.C. Lee ◽  
J.A. Eades ◽  
I.M. Robertson ◽  
H.K. Bimbaum
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Objective Lens ◽  
Pole Piece ◽  
Noticeable Effect ◽  
Plan View ◽  
Handling System ◽  
Transmission Electron ◽  
Environmental Cell ◽  
Cell Transmission

The ability to observe directly and at high spatial resolution the interactions between environments and materials affords the material scientist new and unique opportunities. This capability is realized in the Environmental Cell Transmission Electron Microscope Facility which has been installed as part of the Center for Microanalysis of Materials at the Materials Research Laboratory of the University of Illinois at Urbana-Champaign.The Facility is based on a JEOL 4000EX equipped with a specially designed pole piece. An aperture limited, differentially pumped, environmental cell has been installed in this pole piece. The system is shown schematically in Figures 1 and 2. Figure 1 is a plan view of a section through the objective lens pole-piece, with the microscope axis perpendicular to the plane of the paper, showing the cell enclosing the sample rod, the gas handling system and the location of the magnetically levitated Turbo-Molecular pumps. Figure 2 shows a cross-sectional view of the environmental cell and the gas handling system. As shown in Figure 2 the electron beam passes through a series of five apertures which allow the column vacuum to be maintained while the cell pressure is increased. The actual cell apertures are located at the apex of cones to minimize the gas path length, allow maximum tilt and still permit high- angle diffraction data to be obtained. Differential pumping of the cell is achieved by the four turbo- molecular pumps, the location of which can be seen in the Figures. With this arrangement the environmental cell is capable of supporting 400 torr of N2 gas which has no noticeable effect on the microscope operation. This allows the microscope to be operated with a LaB6 filament. The gas handling system was designed to handle a variety of environments including corrosive ones.

scholarly journals The Transmission Confocal Laser Scanning Microscope

1992 ◽  
Vol 00 (9) ◽  
pp. 6-6 ◽  
Author(s):  
David Carter
Keyword(s):  
Laser Scanning ◽  
Confocal Laser Scanning Microscope ◽  
Confocal Laser Scanning ◽  
Research Centre ◽  
Confocal Laser ◽  
Objective Lens ◽  
Scanning Microscope ◽  
Laser Scanning Microscope ◽  
University Of Toronto ◽  
The University

A confocal laser scanning microscope which can collect images in both transmission and reflection modes has been installed and is being tested in the Imaging Laboratories of the John P. Roberts Research Institute, London, Ontario. Designed by Dr. Ted Dixon at the University of Waterloo, it is being developed by a multi-disciplinary research group which includes the Ontario Lasers and Lightwaves Research Centre and the Department of Physiology, University of Toronto; the Radiology, Physics, and Pathology Departments, MacMaster University; and the Zoology Department, University of Western Ontario.Commercial confacal microscopes operate by reflectance or epifluorescence. A pair of scanning mirrors direct a diffuse laser beam in a raster pattern through an objective lens, which focuses it on the specimen. Reflected light passes back along the same light path, being “de-scanned” by the moving mirrors and then diverted by a beam splitter into a detector. On its return to the detector, light from the focal plane is focussed through a pinhole, which blocks light from out-of-focus regions of the spectrum The microscope stage is moved up and down by a stepping motor to collect images at different depths.

Introductory Remarks

1978 ◽  
Vol 36 (3) ◽  
pp. 3-3
Author(s):  
G.T. Simon
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
North America ◽  
International Congress ◽  
Historical Account ◽  
University Of Toronto ◽  
Good Story ◽  
Symbolic Summation ◽  
The University

Forty years ago in the University of Toronto, a group of young physicists constructed the first electron microscope in North America. With Toronto as the host for the 9th International Congress on Electron Microscopy in 1978, it is an unique opportunity to commemorate this Canadian achievement. In the summer of 1977, Cecil Hall, who was involved in this achievement, wrote in a letter about this commemoration: “It is only a ceremony, of course, a symbolic summation to a story that many of us know. It is a good story”. That it is more than a “good story” became clear while material was being gathered to write the historical account of the construction of the Toronto microscope.

The Observation of Channeling Patterns in Silicon Single Crystals at 200-500 kv

1970 ◽  
Vol 28 ◽  
pp. 44-45
Author(s):  
R. H. Geiss ◽  
K. R. Lawless
Keyword(s):  
Electron Microscope ◽  
Single Crystals ◽  
Simultaneous Action ◽  
Objective Lens ◽  
Transmission Electron ◽  
Backscattered Electron ◽  
The Difference ◽  
Single Field ◽  
Convergent Beam ◽  
The University

Transmission electron channeling patterns, the complement to the backscattered electron blocking patterns seen by Coates in the scanning electron microscope, have been observed in near perfect single crystals of silicon with the 500 kV electron microscope at the University of Virginia. Such channeling patterns, which are thought to be associated with the anomalous absorption and transmission of the Block waves describing the electrons inside a crystal, have all the characteristics of Kikuchi patterns and are but another example of the convergent beam phenomena first demonstrated by Kossel and Möllenstedt in 1939.The difference between the work discussed here and that of Kossel and Möllenstedt and others using convergent beam techniques is that in our experiments the sample is placed near the center of a single field condenser-objective lens. The pre-field of the lens forms a convergent beam with an angular spread of approximately 10−2 radians and gives rise in the channeling pattern, while the post-field acts as an ordinary objective lens and enables defects in the sample to be imaged. The simultaneous action of these fields therefore yields images wherein defects are seen superimposed on the channeling pattern.

Radial Access Straining, Tilting and Elevating Sample Holders

1970 ◽  
Vol 28 ◽  
pp. 342-343
Author(s):  
R. H. Geiss ◽  
W. B. Thompson
Keyword(s):  
Electron Microscope ◽  
The Other ◽  
Distinct Advantage ◽  
Objective Lens ◽  
University Of Virginia ◽  
Special Operations ◽  
The University ◽  
Standard Operations ◽  
Gap Mode ◽  
Type Sample

With the 500 kV electron microscope at the University of Virginia there are two different methods of introducing samples in the transmission mode. In one of these cartridges are inserted into a stage above the objective lens similar to that in the EMU-4, while in the other the cartridge is inserted radially to an “in-gap” stage between the pole pieces of the objective lens. To expand the research capabilities of the in-gap mode several modifications were made to allow the use of rod type sample holders. These modifications include a newly designed air lock, with pre-pump facilities, a new stage and several sample holders. The use of rod type sample holders has the distinct advantage of possible 360° rotation of the sample about the rod axis for any of the standard operations, e.g., straining, heating, cooling, rotating and tilting, as well as some special operations.

A History of the First North American Electron Microscope

1978 ◽  
Vol 36 (3) ◽  
pp. 4-17 ◽  
Author(s):  
U.M. Franklin ◽  
G.C. Weatherly ◽  
G.T. Simon
Keyword(s):  
Electron Microscope ◽  
Resolving Power ◽  
Production Model ◽  
Practical Application ◽  
University Of Toronto ◽  
Transmission Electron ◽  
History Of ◽  
Radio Corporation Of America ◽  
The University ◽  
Better Than

North America's first Transmission Electron Microscope -- and the first of immediate practical application anywhere -- was designed by two graduate students in the Department of Physics at the University of Toronto over the 1937-38 Christmas holidays and was built during the first four months of 1938. By April it produced consistently promising micrographs and before the end of the year, demonstrated magnifications of 20,000 diameters with resolution better than 140Å. The resolving power had been pushed to less than 608. (30 atom diameters) within another ten months. The design of this microscope was adopted by the Radio Corporation of America and developed into the prototype of a commercial series. It was this RCA production model, based directly on the Toronto microscope, that was the equipment selected by laboratories throughout the world for a generation. This represented an extraordinary achievement for the two young Canadians: Albert Prebus and James Hillier.

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