Thermal Considerations in Lens Regulator Systems

1970 ◽  
Vol 28 ◽  
pp. 358-359
Author(s):  
K.C. Newton
Keyword(s):  
Electron Microscope ◽  
Thermal Effects ◽  
Environmental Control ◽  
Reference Networks ◽  
Better Than

Thermal effects in lens regulator systems have become a major problem with the extension of electron microscope resolution capabilities below 5 Angstrom units. Larger columns with immersion lenses and increased accelerating potentials have made solutions more difficult by increasing the power being handled. Environmental control, component choice, and wiring design provide answers, however. Figure 1 indicates with broken lines where thermal problems develop in regulator systemsExtensive environmental control is required in the sampling and reference networks. In each case, stability better than I ppm/min. is required. Components with thermal coefficients satisfactory for these applications without environmental control are either not available or priced prohibitively.

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.

Resolution and measurement in the scanning electron microscope

1987 ◽  
Vol 45 ◽  
pp. 534-537 ◽  
Author(s):  
Michael T. Postek
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Engineering Design ◽  
Resolving Power ◽  
Practical Applications ◽  
Instrument Resolution ◽  
Accurate Definition ◽  
Definition Of ◽  
Scanning Electron ◽  
Better Than

The term ultimate resolution or resolving power is the very best performance that can be obtained from a scanning electron microscope (SEM) given the optimum instrumental conditions and sample. However, as it relates to SEM users, the conventional definitions of this figure are ambiguous. The numbers quoted for the resolution of an instrument are not only theoretically derived, but are also verified through the direct measurement of images on micrographs. However, the samples commonly used for this purpose are specifically optimized for the measurement of instrument resolution and are most often not typical of the sample used in practical applications.SEM RESOLUTION. Some instruments resolve better than others either due to engineering design or other reasons. There is no definitively accurate definition of how to quantify instrument resolution and its measurement in the SEM.

Scanning Secondary Electron Microscopy of Myofibrils Using Transmission Techniques

1975 ◽  
Vol 33 ◽  
pp. 556-557
Author(s):  
M. K. Lamvik
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Carbon Films ◽  
Photographic Recording ◽  
Transmission Electron ◽  
Thin Carbon ◽  
The Common ◽  
Scanning Electron ◽  
Better Than ◽  
Cellular Organelles

When observing small objects such as cellular organelles by scanning electron microscopy, it is often valuable to use the techniques of transmission electron microscopy. The common practice of mounting and coating for SEM may not always be necessary. These possibilities are illustrated using vertebrate skeletal muscle myofibrils.Micrographs for this study were made using a Hitachi HFS-2 scanning electron microscope, with photographic recording usually done at 60 seconds per frame. The instrument was operated at 25 kV, with a specimen chamber vacuum usually better than 10-7 torr. Myofibrils were obtained from rabbit back muscle using the method of Zak et al. To show the component filaments of this contractile organelle, the myofibrils were partially disrupted by agitation in a relaxing medium. A brief centrifugation was done to clear the solution of most of the undisrupted myofibrils before a drop was placed on the grid. Standard 3 mm transmission electron microscope grids covered with thin carbon films were used in this study.

Water accumulation as a function of temperature on specimens in an electron microscope cold stage

1986 ◽  
Vol 44 ◽  
pp. 114-115 ◽  
Author(s):  
M.K. Lamvik ◽  
D.A. Kopf ◽  
S.D. Davilla ◽  
J.D. Robertson
Keyword(s):  
Electron Microscope ◽  
Mass Loss ◽  
Liquid Helium ◽  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Liquid Helium Temperature ◽  
Helium Temperature ◽  
Cold Stage ◽  
Water Accumulation ◽  
Better Than

Last year we reported1 that there is a striking reduction in the rate of mass loss when a specimen is observed at liquid helium temperature. It is important to determine whether liquid helium temperature is significantly better than liquid nitrogen temperature. This requires a good understanding of mass loss effects in cold stages around 100K.

Atomic resolution AEM (ARAEM) of oxide superconductors

1992 ◽  
Vol 50 (1) ◽  
pp. 74-75
Author(s):  
Vinayak P. Dravid ◽  
H. Zhang ◽  
L.D. Marks ◽  
J.P. Zhang
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Atomic Resolution ◽  
Oxide Superconductors ◽  
Electron Holography ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Point To Point ◽  
Single Instrument ◽  
Better Than

A 200 kV cold field emission gun atomic resolution analytical electron microscope (ARAEM, Hitachi HF-2000) has been recently installed at Northwestern. The ARAEM offers an unprecedented combination of atomic structure imaging of better than 0.20 nm nominal point-to-point resolution and about 0.10 nm line resolution, alongwith nanoscale analytical capabilities and electron holography in one single instrument. The ARAEM has been fully functional/operational and this paper presents some illustrative examples of application of ARAEM techniques to oxide superconductors. Additional results will be presented at the meeting.

Development of 200kV ultrahigh-resolution analytical electron microscope

1989 ◽  
Vol 47 ◽  
pp. 108-109
Author(s):  
T. Kaneyama ◽  
M. Naruse ◽  
Y. Ishida ◽  
M. Kersker
Keyword(s):  
Electron Microscope ◽  
Optical Constants ◽  
Materials Science ◽  
Objective Lens ◽  
The Finite Element Method ◽  
Ultrahigh Resolution ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Characteristic Features ◽  
Better Than

In the field of materials science, the importance of the ultrahigh resolution analytical electron microscope (UHRAEM) is increasing. A new UHRAEM which provides a resolution of better than 0.2 nm and allows analysis of a few nm areas has been developed. [Fig. 1 shows the external view] The followings are some characteristic features of the UHRAEM.Objective lens (OL)Two types of OL polepieces (URP for ±10' specimen tilt and ARP for ±30' tilt) have been developed. The optical constants shown in the table on the next page are figures calculated by the finite element method. However, Cs was experimentally confirmed by two methods (namely, Beam Tilt method and Krivanek method) as 0.45 ∼ 0.50 mm for URP and as 0.9 ∼ 1.0 mm for ARP, respectively. Fig. 2 shows an optical diffractogram obtained from a micrograph of amorphous carbon with URP under the Scherzer defocus condition. It demonstrates a resolution of 0.19 nm and a Cs smaller than 0.5 mm.

Tensile Property Evaluation of Carbon Fiber Reinforced Aluminium Sandwich Composites

2014 ◽  
Vol 984-985 ◽  
pp. 345-349 ◽  
Author(s):  
U. Tamilarasan ◽  
L. Karunamoorthy ◽  
K. Palanikumar
Keyword(s):  
Electron Microscope ◽  
Composite Materials ◽  
Tensile Property ◽  
Composite Laminates ◽  
Sandwich Composite ◽  
Property Evaluation ◽  
New Applications ◽  
Fractured Surface ◽  
Scanning Electron ◽  
Better Than

Composite materials are finding new applications in many situations and are better than the conventional materials because of their excellent properties. In the present investigation, aluminium sandwich composite laminates are fabricated and their tensile property is evaluated. The structure of the composites and their fractured surface are studied by using Scanning Electron Microscope. The analysis of the experimental results indicated that the incorporation of aluminium stack as sandwich improves the properties and can be used as a structural material for construction.

Thermal Effects on the Anchoring of Flexible Pipe Tensile Armors

2015 ◽  
Author(s):  
Olaf O. Otte Filho ◽  
Rafael L. Tanaka ◽  
Rafael G. Morini ◽  
Rafael N. Torres ◽  
Thamise S. V. Vilela
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Thermal Effects ◽  
Current Model ◽  
Element Model ◽  
Small Scale ◽  
Flexible Pipe ◽  
System A ◽  
Flexible Pipes ◽  
Better Than

In the design of flexible pipes, predict the anchoring behavior on end fittings is always challenging. In this sense, Prysmian Surflex has developed a finite element model, which should help the end fitting design as well the prediction of the structural behavior and the acceptable maximum loads. The current model considers that the contact between armor-resin is purely cohesive and has been suitable for the design of end fittings [1] and [2]. But tests and new studies [3] and [4] indicate that only cohesive assumption would not be the best approach. Experimental data from prototype tests also show that the current model would not predict acceptable results for loads higher than those used in previous projects. This document will describe a study developed considering the friction and thermal contraction, instead of the cohesive phenomenon in the anchoring behavior analysis. Small scale tests were conducted in order to understand the anchoring relation between the resin and the wire used in the tensile armor. For this purpose, a special test device was developed to simulate an enclosure system. A parametric study was also performed to identify the cooling temperatures, coefficients of friction and contact properties parameters taken from small scale tests. The finite element model considers the thermal effects during exothermic curing. Using the new parameters obtained, a second model was developed. This model consists of only one real shaped bended wire inside an end fitting cavity. To validate the model, samples were tested on laboratory according anchoring design. The results of this round of tests were studied and corroborate the argument that use friction and thermal effects is better than use only the cohesive condition.

Voltage and Dopant Concentration Measurements of Semiconductors using a Band-Pass Toroidal Energy Analyzer Inside a Scanning Electron Microscope

2015 ◽  
Vol 21 (4) ◽  
pp. 910-918 ◽  
Author(s):  
Avinash Srinivasan ◽  
Anjam Khursheed
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Dopant Concentration ◽  
High Signal ◽  
Energy Analyzer ◽  
Order Of Magnitude ◽  
Band Pass ◽  
Concentration Measurements ◽  
Scanning Electron ◽  
Better Than

AbstractThis paper presents experimental results obtained from a scanning electron microscope (SEM) second-order focusing toroidal electron energy analyzer attachment. The results demonstrate that the analyzer can be used to obtain high signal-to-noise voltage and dopant concentration measurements on semiconductors in the presence of different electric field conditions at the sample. The experimentally calculated relative error of measurement typically varies from 31 to 63, corresponding to secondary electron (SE) signal mean shifts of 9–18 mV. The millivolt accuracy of these results is over one order of magnitude better than earlier quantitative dopant concentration measurements made by a retarding field analyzer.

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