Thickness Measurement in the AEM by Macintosh-Based Analysis of Two-Beam Convergent Beam Patterns

1990 ◽  
Vol 48 (2) ◽  
pp. 504-505
Author(s):  
John F. Mansfield ◽  
Douglas C. Crawford
Keyword(s):  
Electron Microscope ◽  
Video Camera ◽  
Thickness Measurement ◽  
Specimen Thickness ◽  
Crystalline Materials ◽  
Beam Dynamic ◽  
Line Measurement ◽  
On Line ◽  
Image Position ◽  
Convergent Beam

A method has been developed that allows on-line measurement of the thickness of crystalline materials in the analytical electron microscope. Two-beam convergent beam electron diffraction (CBED) patterns are digitized from a JEOL 2000FX electron microscope into an Apple Macintosh II microcomputer via a Gatan #673 CCD Video Camera and an Imaging Systems Technology Video 1000 frame-capture board. It is necessary to know the lattice parameters of the sample since measurements are made of the spacing of the diffraction discs in order to calibrate the pattern. The sample thickness is calculated from measurements of the spacings of the fringes that are seen in the diffraction discs. This technique was pioneered by Kelly et al, who used the two-beam dynamic theory of MacGillavry relate the deviation parameter (Si) of the ith fringe from the exact Bragg condition to the specimen thickness (t) with the equation:Where ξg, is the extinction distance for that reflection and ni is an integer.

On-line measurement of specimen thickness by Convergent Beam Electron Diffraction

1990 ◽  
Vol 48 (2) ◽  
pp. 480-481
Author(s):  
Max T. Otten
Keyword(s):  
Electron Diffraction ◽  
Thickness Measurement ◽  
Dark Field ◽  
Convergent Beam Electron Diffraction ◽  
Specimen Thickness ◽  
Bright Field ◽  
Beam Electron ◽  
Kikuchi Line ◽  
On Line ◽  
Convergent Beam

Convergent Beam Electron Diffraction (CBED) thickness measurement is the easiest and most accurate way of determining the thickness of crystalline materials. The method was described by Kelly et al. The specimen thickness can be calculated from a few measurements on a recorded diffraction pattern in a matter of minutes (by hand) or seconds (by a computer program).For thickness measurement a CBED pattern is needed that contains a two-beam diffracting condition, with a dark Kikuchi line going through the centre of the Bright-Field disc and the corresponding bright Kikuchi line through the centre of a Dark-Field disc. Parallel to the bright Kikuchi line, the Dark-Field disc contains a number of fringes (Fig. 1) whose distance from the Kikuchi line varies with specimen thickness. The data needed for a measurement are the electron wavelength, the d-spacing dhkl of the diffraction used, the distance 2θB between the Bright-Field disc and Dark-Field disc in the CBED pattern, and the distances Δθi between the dark thickness fringes and the bright Kikuchi line in the Dark-Field disc (Fig. 2).

Non-Contact Coating Thickness Measurement

1998 ◽  
Author(s):  
P.E. Chandler ◽  
M.B.C. Quigley ◽  
J.F. Fletcher
Keyword(s):  
Coating Thickness ◽  
Thickness Measurement ◽  
Coating Structure ◽  
Line Measurement ◽  
Infra Red ◽  
On Line ◽  
Coating Thickness Measurement ◽  
Accuracy Of Measurement ◽  
Engine Components ◽  
Spraying Process

Abstract There are many instances of coatings that require a nondestructive and non-contact measure of coating thickness as part of a quality control system. Specifically, this paper reports on experiments carried out on non-contact measurements of MCrAIY and TBC coatings. The system uses an infra red beam from a solid state laser to generate a thermal wave in the coating. When this wave reaches the substrate an interference effect is caused. The modulated input heating produces a modulated output infra red signal from the surface and at a different wavelength from the laser beam. The output signal has a phase difference from the input signal which is related to the coating thickness. As neither the laser nor the detector are in contact with the surface of the coating and the temperature of the coating is raised by only a few degrees this represents a non-contact NDE system. This system has been tested across a range of coating/substrate combinations. In this paper we give examples of MCrAIY and TBC coatings applied to engine components demonstrating that the accuracy of measurement is only limited by the roughness of the coating structure and substrate. The use of this system for on-line measurement during the spraying process is also discussed and results presented.

Sputter-Deposited Films as Standards for Tem X-Ray Analysis

1980 ◽  
Vol 38 ◽  
pp. 134-135
Author(s):  
A. F. Marshall ◽  
C. Zercher
Keyword(s):  
Thin Film ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Specimen Thickness ◽  
Detector Efficiency ◽  
X Ray ◽  
Transmission Electron ◽  
Sputter Deposited ◽  
Image Position ◽  
Deposited Films

Quantitative energy dispersive x-ray analysis in the transmission electron microscope is generally obtained in the form of relative concentrations using the equation: where CA, CB are the concentrations and IA, IB are the peak intensities of elements A and B, and kAB is a constant which is independent of specimen composition and specimen thickness, assuming the thin film criterion is satisfied. kAB may be determined experimentally from standards (Cliff-Lorimer technique1), or may be calculated from considerations of x-ray generation and detector efficiency for the elements being analyzed2. Due to differences in detector parameters, kAB may vary from instrument to instrument.

Convergent-Beam Diffraction in the Characterization of Crystalline Phases

1985 ◽  
Vol 62 ◽  
Author(s):  
J. A. Eades ◽  
M. J. Kaufman ◽  
H. L. Fraser
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Zone Axis ◽  
Crystalline Materials ◽  
Powerful Technique ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Diffraction ◽  
Convergent Beam Diffraction

ABSTRACTConvergent-beam diffraction in the transmission electron microscope is a powerful technique for the characterization of crystalline materials. Examples are presented to show the way in which convergent-beam zone-axis patterns can be used to determine: the unit cell; the symmetry; the strain of a crystal. The patterns are also recognizable and so can be used, like fingerprints, to identify phases.

On-Line Measurement of Foil Thickness from Convergent Beam Electron Diffraction Patterns

1982 ◽  
Vol 40 ◽  
pp. 694-695
Author(s):  
J. Bentleyt ◽  
G. L. Lehman
Keyword(s):  
Electron Diffraction ◽  
Materials Science ◽  
Convergent Beam Electron Diffraction ◽  
Foil Thickness ◽  
Beam Electron ◽  
Line Measurement ◽  
On Line ◽  
Graphical Technique ◽  
Diffraction Patterns ◽  
Convergent Beam

Accurate values of foil thickness are required in many materials science applications, such as for measurement of defect concentrations and for x-ray microanalysis absorption corrections. Kelly et al. demonstrated that convergent beam electron diffraction (CBED) patterns can be analyzed using a simple graphical technique to give values for foil thickness with ±2% accuracy. More recently, Allen extended the treatment to make use of both maxima and minima in the CBED disks. The technique requires a knowledge of the d-spacing of the reflection, the electron wavelength, an evaluation of the deviation parameter, si, associated with the i-th fringe in the diffracted beam disk, and the assignment of a set of constants to "index" the fringes.

scholarly journals The Assessment of Cross Machine Openness Uniformity of a Fiber Feed Matt

2000 ◽  
Vol os-9 (4) ◽  
pp. 1558925000OS-90
Author(s):  
Ayad Oumera ◽  
Abdelfattah M. Seyam ◽  
William Oxenham
Keyword(s):  
Thickness Measurement ◽  
One Dimensional ◽  
Line Measurement ◽  
On Line ◽  
Compression Data ◽  
The One ◽  
Compression Characteristics ◽  
Input Level

The one-dimensional characteristic of yarn has resulted in very little attention being given to the uniformity of carded web in the cross machine direction. The development of nonwovens has prompted researchers to reconsider the importance of cross machine uniformity in determining the total uniformity of the carded web. It is therefore important to develop manual and online techniques to quantify cross machine uniformity at both the input and output of the card. At the card input, uniformity is taken as representing both mass and openness characteristics of the feed matt. While at the card output, there are many available techniques that allow the on-line measurement of the mass uniformity of the carded web, determination of uniformity at the input level is more difficult. The approach that was taken was to use an off-line technique to find the mass and openness of the feed matt at different locations across the card. While traditionally mass as a property has been given a lot of importance, much less attention has been given to the concept of openness. This is due in part to the difficulty in quantifying openness. Openness is believed to have great significance in determining the overall quality of the carded web, especially with regard to the formation of neps. In order to make the concept of openness more clear, it was found necessary to develop a way of quantifying it. This was done by performing a compression test on the feed matt, and then fitting the compression data with an exponential curve. The coefficient of the exponent was used to represent openness. This approach was used to find the effect of the feed roller (pin type) on cross machine uniformity. It was found that the squeezing of the feed roller did not have an effect in redistributing the mass of the feed matt, but did have an effect in changing the openness of the feed matt. Because of the difficulty involved in the handling of the feed matt, a newly developed technique is suggested to characterize openness. While this method still relies on the compression characteristics of the feed matt, it is more appropriate because it is performed on-line. Preliminary results are reported. It was found that thickness measurement under carefully selected pressure value could be used to characterize openness precisely.

Simple Identification of Electron Diffraction Ring Patterns

1969 ◽  
Vol 27 ◽  
pp. 160-161
Author(s):  
Carolyn Nohr ◽  
Ann Ayres
Keyword(s):  
Electron Microscope ◽  
Electron Diffraction ◽  
Diffraction Ring ◽  
Image Position

Texts on electron diffraction recommend that the camera constant of the electron microscope be determine d by calibration with a standard crystalline specimen, using the equation

Resolution of a Transmitted Electron Image Formed by A Scanning Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 386-387
Author(s):  
S. Takashima ◽  
H. Hashimoto ◽  
S. Kimoto
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Specimen Thickness ◽  
Probe Diameter ◽  
Transmission Electron ◽  
Electron Image ◽  
Conventional Transmission Electron Microscope ◽  
Scanning Electron

The resolution of a conventional transmission electron microscope (TEM) deteriorates as the specimen thickness increases, because chromatic aberration of the objective lens is caused by the energy loss of electrons). In the case of a scanning electron microscope (SEM), chromatic aberration does not exist as the restrictive factor for the resolution of the transmitted electron image, for the SEM has no imageforming lens. It is not sure, however, that the equal resolution to the probe diameter can be obtained in the case of a thick specimen. To study the relation between the specimen thickness and the resolution of the trans-mitted electron image obtained by the SEM, the following experiment was carried out.

A New 1000kv Electron Microscope

1969 ◽  
Vol 27 ◽  
pp. 100-101
Author(s):  
J.L. Williams ◽  
K. Heathcote ◽  
E.J. Greer
Keyword(s):  
Electron Microscope ◽  
Direct Observation ◽  
High Voltage ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Specimen Thickness ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
Dynamic Experiments ◽  
Conventional Instrument

High Voltage Electron Microscope already offers exciting experimental possibilities to Biologists and Materials Scientists because the increased specimen thickness allows direct observation of three dimensional structure and dynamic experiments on effectively bulk specimens. This microscope is designed to give maximum accessibility and space in the specimen region for the special stages which are required. At the same time it provides an ease of operation similar to a conventional instrument.

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