A fast method of calculating diffraction patterns on inside cylindrical surface

2014 ◽  
Author(s):  
Jun Wang ◽  
Qionghua Wang ◽  
Yuhen Hu
Keyword(s):  
Cylindrical Surface ◽  
Fast Method ◽  
Diffraction Patterns

New pole figure calculation software:2DiffCalc

2009 ◽  
Vol 42 (4) ◽  
pp. 730-733 ◽  
Author(s):  
Ulf Garbe
Keyword(s):  
Pole Figure ◽  
Peak Position ◽  
Fast Method ◽  
Texture Measurement ◽  
Area Detector ◽  
Pole Figures ◽  
Diffraction Patterns ◽  
Research Facilities ◽  
Standard Software ◽  
Large Research

At neutron and synchrotron radiation research facilities, texture measurement with area detectors leads to a large amount of data. During the measurement time, a preliminary analysis of the acquired diffraction patterns is essential. A first view of the resulting pole figures affords the opportunity to evaluate the measurement and to change the instrument parameters accordingly. At a large research facility, the instrument is built with unique adaptations to different scientific cases. At this stage, there is no commercial standard software available to analyse the measured raw data. For these purposes, new software,2DiffCalc, was developed to provide a fast method for pole figure calculation. This software is able to determine the pole figure intensities automatically from the measured area-detector images.2DiffCalccalculates the integral intensities, peak position and width in combination with the pole figure angles.

Fast method of computing Fresnel diffraction patterns

2001 ◽  
Author(s):  
Masahiro Ueno ◽  
Yoshiaki Kurokawa ◽  
Takaya Tanabe ◽  
Manabu Yamamoto
Keyword(s):  
Fresnel Diffraction ◽  
Fast Method ◽  
Diffraction Patterns

Calculation of Diffraction Patterns on inside Cylindrical Surface

2014 ◽  
Vol 533 ◽  
pp. 260-263
Author(s):  
Jun Wang ◽  
Yu Hen Hu ◽  
Xin Zhou ◽  
Da Hai Li ◽  
Qiong Hua Wang
Keyword(s):  
Calculation Method ◽  
Cylindrical Surface ◽  
Light Sources ◽  
Object Surface ◽  
Computer Generated Holograms ◽  
Simulation Results ◽  
Diffraction Patterns ◽  
Point Light

In this paper, we propose a calculation method of diffraction patterns on inside cylindrical surface. The proposed method applies the Huygens-Fresnel principle and derives the diffraction distributions on the inside observation surface, which are propagated from point light sources on the outside concentric object surface. Although the calculation of diffraction patterns on the outside observation surface has been reported in the literature, that on the inside cylindrical surface is much different, and it has not been reported in the best of our knowledge. The simulation results of Youngs fringe, as the simplest example of our method, and the diffraction patterns on cylindrical observation with cylindrical image demonstrated the validity of the proposed method. Our method is extremely useful in creating cylindrical computer-generated holograms.

Indexing of powder diffraction patterns by iterative use of singular value decomposition

2003 ◽  
Vol 36 (1) ◽  
pp. 86-95 ◽  
Author(s):  
A. A. Coelho
Keyword(s):  
Singular Value Decomposition ◽  
Powder Diffraction ◽  
Present Method ◽  
Linear Equations ◽  
Noisy Data ◽  
Simulated Data ◽  
Singular Value ◽  
Fast Method ◽  
Diffraction Patterns ◽  
Value Decomposition

A fast method for indexing powder diffraction patterns has been developed for large and small lattices of all symmetries. The method is relatively insensitive to impurity peaks and missing highd-spacings: on simulated data, little effect in terms of successful indexing has been observed when one in threed-spacings are randomly removed. Comparison with three of the most popular indexing programs, namelyITO,DICVOL91andTREOR90, has shown that the present method as implemented in the programTOPASis more successful at indexing simulated data. Also significant is that the present method performs well on typically noisy data with large diffractometer zero errors. Critical to its success, the present method uses singular value decomposition in an iterative manner for solving linear equations relatinghklvalues tod-spacings.

Light Optical Diffraction Studies of Macromolecular Ultrastructure

1970 ◽  
Vol 28 ◽  
pp. 258-259
Author(s):  
Glen B. Haydon
Keyword(s):  
High Resolution ◽  
Diffraction Analysis ◽  
Diffraction Pattern ◽  
Electron Micrographs ◽  
Optical Diffraction ◽  
Electron Micrograph ◽  
Its Analysis ◽  
Resolution Electron ◽  
Diffraction Patterns

Analysis of light optical diffraction patterns produced by electron micrographs can easily lead to much nonsense. Such diffraction patterns are referred to as optical transforms and are compared with transforms produced by a variety of mathematical manipulations. In the use of light optical diffraction patterns to study periodicities in macromolecular ultrastructures, a number of potential pitfalls have been rediscovered. The limitations apply to the formation of the electron micrograph as well as its analysis.(1) The high resolution electron micrograph is itself a complex diffraction pattern resulting from the specimen, its stain, and its supporting substrate. Cowley and Moodie (Proc. Phys. Soc. B, LXX 497, 1957) demonstrated changing image patterns with changes in focus. Similar defocus images have been subjected to further light optical diffraction analysis.

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Two Investigations into Grain Boundary Structure

1977 ◽  
Vol 35 ◽  
pp. 688-691
Author(s):  
P. Humble
Keyword(s):  
Grain Boundary ◽  
Dark Field ◽  
Boundary Structure ◽  
Boundary Dislocation ◽  
Bright Field ◽  
Intrinsic Structure ◽  
Weak Beam ◽  
Grain Boundary Structure ◽  
Independent Information ◽  
Diffraction Patterns

There has been sustained interest over the last few years into both the intrinsic (primary and secondary) structure of grain boundaries and the extrinsic structure e.g. the interaction of matrix dislocations with the boundary. Most of the investigations carried out by electron microscopy have involved only the use of information contained in the transmitted image (bright field, dark field, weak beam etc.). Whilst these imaging modes are appropriate to the cases of relatively coarse intrinsic or extrinsic grain boundary dislocation structures, it is apparent that in principle (and indeed in practice, e.g. (1)-(3)) the diffraction patterns from the boundary can give extra independent information about the fine scale periodic intrinsic structure of the boundary.In this paper I shall describe one investigation into each type of structure using the appropriate method of obtaining the necessary information which has been carried out recently at Tribophysics.

Disappearance Voltage Determinations Using a Convergent Beam

1971 ◽  
Vol 29 ◽  
pp. 184-185
Author(s):  
W. L. Bell
Keyword(s):  
Second Order ◽  
Objective Method ◽  
Uniform Thickness ◽  
Rocking Curve ◽  
Crystal Perfection ◽  
Kikuchi Line ◽  
Central Maximum ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Beam Technique

Disappearance voltages for second order reflections can be determined experimentally in a variety of ways. The more subjective methods, such as Kikuchi line disappearance and bend contour imaging, involve comparing a series of diffraction patterns or micrographs taken at intervals throughout the disappearance range and selecting that voltage which gives the strongest disappearance effect. The estimated accuracies of these methods are both to within 10 kV, or about 2-4%, of the true disappearance voltage, which is quite sufficient for using these voltages in further calculations. However, it is the necessity of determining this information by comparisons of exposed plates rather than while operating the microscope that detracts from the immediate usefulness of these methods if there is reason to perform experiments at an unknown disappearance voltage.The convergent beam technique for determining the disappearance voltage has been found to be a highly objective method when it is applicable, i.e. when reasonable crystal perfection exists and an area of uniform thickness can be found. The criterion for determining this voltage is that the central maximum disappear from the rocking curve for the second order spot.

Electronic Cone Illumination with the Conventional Transmission Electron Microscope

1977 ◽  
Vol 35 ◽  
pp. 72-73
Author(s):  
William Krakow
Keyword(s):  
Electronic Device ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Hollow Cone ◽  
Transmission Electron ◽  
Lissajous Figures ◽  
High Resolution Images ◽  
Imaging Mode ◽  
Diffraction Patterns ◽  
Transmission Microscope

An electronic device has been constructed which manipulates the primary beam in the conventional transmission microscope to illuminate a specimen under a variety of virtual condenser aperture conditions. The device uses the existing tilt coils of the microscope, and modulates the D.C. signals to both x and y tilt directions simultaneously with various waveforms to produce Lissajous figures in the back-focal plane of the objective lens. Electron diffraction patterns can be recorded which reflect the manner in which the direct beam is tilted during exposure of a micrograph. The device has been utilized mainly for the hollow cone imaging mode where the device provides a microscope transfer function without zeros in all spatial directions and has produced high resolution images which are also free from the effect of chromatic aberration. A standard second condenser aperture is employed and the width of the cone annulus is readily controlled by defocusing the second condenser lens.

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