Вычислительная модель рентгеновской компьютерной томографии с функцией оценки плотности

2021 ◽  
Vol 3 ◽  
pp. 53-65
Author(s):  
С.П. Осипов ◽  
И.Г. Ядренкин ◽  
С.В. Чахлов ◽  
О.С. Осипов ◽  
Е.Ю. Усачёв
Keyword(s):  
Test Object ◽  
Parallel Beam ◽  
X Ray ◽  
Virtual Test ◽  
Beam Geometry ◽  
Estimation Function ◽  
Parallel Beam Geometry ◽  
X Ray Computed ◽  
Mathcad Software ◽  
Test Objects

A computational model of X-ray computed tomography with a density estimation function in the parallel beam geometry is proposed. The model includes blocks for simulating and correcting sinograms and reconstructing slices of test object. When generating sinograms, the parameters of the test object, source and detector of X-ray radiation are taken into account. Algorithms of simulation are implemented in the MathCad software and are tested on virtual test objects.

scholarly journals Calculation Model of X-Ray Computed Tomography with Density Assessment Function

2021 ◽  
Vol 57 (3) ◽  
pp. 222-237
Author(s):  
S. P. Osipov ◽  
I. G. Yadrenkin ◽  
S. V. Chakhlov ◽  
O. S. Osipov ◽  
E. Yu. Usachev ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Test Object ◽  
Calculation Model ◽  
Parallel Beam ◽  
X Ray ◽  
Virtual Test ◽  
X Ray Computed ◽  
Test Objects ◽  
Density Assessment

Abstract— A calculation model of X-ray computed tomography with a density assessment function in the geometry of a parallel beam has been proposed. The model includes blocks for simulating and correcting sinograms and reconstructing section images. When generating sinograms, the parameters of the test object, source, and recorder of X-ray radiation have been taken into account. Modeling algorithms are implemented in the MathCad system and tested on virtual test objects.

X-ray Diffraction Studies of Polycrystalline Thin Films Using Glancing Angle Diffractometry

1988 ◽  
Vol 32 ◽  
pp. 311-321 ◽  
Author(s):  
R.A. Larsen ◽  
T.F. McNulty ◽  
R.P. Goehner ◽  
K.R. Crystal
Keyword(s):  
Thin Films ◽  
Deep Penetration ◽  
X Ray Diffraction ◽  
Parallel Beam ◽  
X Ray ◽  
Beam Geometry ◽  
Polycrystalline Thin Films ◽  
Glancing Angle ◽  
Parallel Beam Geometry

AbstractThe use of conventional θ/2θ diffraction methods for the characterization of polycrystalline thin films is not in general a satisfactory technique due to the relatively deep penetration of x-ray photons in most materials. Glancing incidence diffraction (GID) can compensate for the penetration problems inherent in the θ/2θ geometry. Parallel beam geometry has been developed in conjunction with GID to eliminate the focusing aberrations encountered when performing these types of measurements. During the past yearwe developed a parallel beam attachment which we have successfully configured to a number of systems.

Application of a single-reflection collimating multilayer optic for X-ray diffraction experiments employing parallel-beam geometry

2008 ◽  
Vol 41 (1) ◽  
pp. 124-133 ◽  
Author(s):  
M. Wohlschlögel ◽  
T. U. Schülli ◽  
B. Lantz ◽  
U. Welzel
Keyword(s):  
Incident Beam ◽  
Grazing Incidence ◽  
Photon Flux ◽  
Data Sets ◽  
Parallel Beam ◽  
X Ray ◽  
Beam Focusing ◽  
Beam Geometry ◽  
Parallel Beam Geometry ◽  
Diffraction Patterns

Instrumental aberrations of a parallel-beam diffractometer equipped with a rotating anode X-ray source, a single-reflection collimating multilayer optic and a parallel-plate collimator in front of the detector have been investigated on the basis of standard measurements (i.e.employing stress- and texture-free isotropic powder specimens exhibiting small or negligible structural diffraction line broadening). It has been shown that a defocusing correction, which is a major instrumental aberration for diffraction patterns collected with divergent-beam (focusing) geometries, is unnecessary for this diffractometer. The performance of the diffractometer equipped with the single-reflection collimating multilayer optic (single-reflection mirror) is compared with the performance of the diffractometer equipped with a Kirkpatrick–Baez optic (cross-coupled Göbel mirror) on the basis of experimental standard measurements and ray-tracing calculations. The results indicate that the use of the single-reflection mirror provides a significant gain in photon flux and brilliance. A high photon flux, high brilliance and minimal divergence of the incident beam make the setup based on the single-reflection mirror particularly suitable for grazing-incidence diffraction, and thus for the investigation of very thin films (yielding low diffracted intensities) and of stress and texture (requiring the acquisition of large measured data sets, corresponding to the variation of the orientation of the diffraction vector with respect to the specimen frame of reference). A comparative discussion of primary optics which can be used to realise parallel-beam geometry shows the range of possible applications of parallel-beam diffractometers and indicates the virtues and disadvantages of the different optics.

Parallel Beam and Focusing X-ray Powder Diffractometry

1988 ◽  
Vol 32 ◽  
pp. 481-488
Author(s):  
W. Parrish ◽  
M. Hart
Keyword(s):  
Lattice Parameter ◽  
Particle Sizes ◽  
Parallel Beam ◽  
Instrument Function ◽  
X Ray ◽  
Experimental Profile ◽  
Beam Geometry ◽  
Parallel Beam Geometry ◽  
Integrated Intensities ◽  
Voigt Function

AbstractComparison of results using synchrotron radiation and X-ray tubes requires a knowledge of the fundamentally different profile shapes inherent in the methods. The varying asymmetric shapes and peak shifts in focusing geometry limit the accuracy and applications of the method and their origins are reviewed. Most o f the focusing aberrations such as specimen displacement, flat specimen and θ-2θ mis-setting do not occur in the parallel beam geometry. The X-ray optics used in synchrotron parallel beam methods produces narrow, symmetrical profiles which can be accurately fit with a pseudo-Voigt function, They have the same shape in the entire pattern. Only the width increases as tanθ due to wavelength dispersion but with higher resolution systems dispersion can be eliminated. The constant instrument function contribution to the experimental profile shape is an important advantage in studies involving profile shapes, e.g., small particle sizes and microstrains, and accurate integrated intensities. The absence of systematic errors leads to more precise lattice parameter determinations.

scholarly journals Effects of Misalignment of Parallel Beam Optics on Thin Film Stress Analysis

2014 ◽  
Vol 996 ◽  
pp. 141-146
Author(s):  
Nicholas Norberg ◽  
Arnold C. Vermeulen
Keyword(s):  
Significant Error ◽  
Film Stress ◽  
Alignment Error ◽  
Beam Optics ◽  
X Ray Diffraction ◽  
Parallel Beam ◽  
X Ray ◽  
Thin Film Stress ◽  
Beam Geometry ◽  
Parallel Beam Geometry

Collecting reliable data is crucial in the research of residual stresses in thin films using X-ray diffraction. The parallel beam geometry has advantage of reliability compared to focusing beam geometry. Though care must be taken to the alignment. A small alignment error may cause a significant error in the stress value. We will show the sensitivity for the misalignment of the parallel beam optics, discuss requirements on hardware alignment and demonstrate a software correction for the presence of remaining hardware errors.

scholarly journals Development of high-resolution x-ray CT system using parallel beam geometry

2016 ◽  
Author(s):  
Akio Yoneyama ◽  
Rika Baba ◽  
Kazuyuki Hyodo ◽  
Tohoru Takeda ◽  
Haruhisa Nakano ◽  
...  
Keyword(s):  
High Resolution ◽  
Parallel Beam ◽  
X Ray ◽  
Beam Geometry ◽  
Parallel Beam Geometry ◽  
Ct System

scholarly journals Characterization of epitaxial ZrO2by X-ray diffractometry with parallel-beam geometry

1996 ◽  
Vol 52 (a1) ◽  
pp. C361-C361
Author(s):  
P. Guinebretière ◽  
A. Dauger ◽  
O. Masson ◽  
B. Soulestin
Keyword(s):  
Parallel Beam ◽  
X Ray ◽  
Beam Geometry ◽  
Parallel Beam Geometry

scholarly journals Influence of Sample-Movement on Particle-Randomization of Powder Samples in the Parallel-Beam Geometry

1997 ◽  
Vol 29 (1-2) ◽  
pp. 27-37
Author(s):  
K. Burger ◽  
J. Ihringer
Keyword(s):  
High Resolution ◽  
Rotation Axis ◽  
Bragg Reflection ◽  
Parallel Beam ◽  
X Ray ◽  
Beam Geometry ◽  
Powder Samples ◽  
Parallel Beam Geometry ◽  
Diffraction Patterns ◽  
Integrated Intensities

Today, from powder X-ray diffraction the scientists want to obtain high resolution diffraction patterns with reliable Bragg-reflection intensities. Two well-known and closely connected obstacles on the way are texture and particle randomization of the sample, which strongly influence the measured intensities. In the work presented here, we examine the second problem.Especially with high resolution diffractometers, for well crystallized or highly absorbing samples the number of contributing crystals in the powder is too small, thus introducing significant errors in the profiles and measured intensities of Bragg-reflections. This may be the major source of inaccuracy in data used for structure determination. Calculations of the error of the integrated intensities are presented, for the high resolution, parallel beam geometry at a synchrotron X-ray source. Results exhibit errors of 40 % in the range of highest resolution for a sample of 3 μm crystals of corundum, with the sample at rest. To enhance randomization, several methods of sample-movement are considered. A new effective method is proposed, where the rotation axis of the flat sample-disk is slightly inclined out of the diffraction plane.

scholarly journals An analytical iterative statistical algorithm for image reconstruction from projections

2014 ◽  
Vol 24 (1) ◽  
pp. 7-17 ◽  
Author(s):  
Robert Cierniak
Keyword(s):  
Image Reconstruction ◽  
Reconstruction Algorithm ◽  
Likelihood Method ◽  
Parallel Beam ◽  
Beam Geometry ◽  
Parallel Beam Geometry ◽  
X Ray Computed ◽  
Image Reconstruction From Projections ◽  
Computed Tomograph ◽  
Conventional Algorithm

Abstract The main purpose of the paper is to present a statistical model-based iterative approach to the problem of image reconstruction from projections. This originally formulated reconstruction algorithm is based on a maximum likelihood method with an objective adjusted to the probability distribution of measured signals obtained from an x-ray computed tomograph with parallel beam geometry. Various forms of objectives are tested. Experimental results show that an objective that is exactly tailored statistically yields the best results, and that the proposed reconstruction algorithm reconstructs an image with better quality than a conventional algorithm with convolution and back-projection.

Use of polycapillary X-ray lenses in the X-ray diffraction measurement of texture

2002 ◽  
Vol 35 (2) ◽  
pp. 196-206 ◽  
Author(s):  
U. Welzel ◽  
M. Leoni
Keyword(s):  
Sample Surface ◽  
Diffraction Measurement ◽  
Finite Sample ◽  
X Ray Diffraction ◽  
Parallel Beam ◽  
X Ray ◽  
Beam Geometry ◽  
Pole Figures ◽  
Finite Sample Size ◽  
Parallel Beam Geometry

Corrections for instrumental aberrations of X-ray diffraction texture measurements (pole-figure measurements) conducted in quasi-parallel-beam geometry using an X-ray lens have been investigated on the basis of measurements on (texture-free) reference samples. It has been shown that a defocusing correction, which is a major correction in the case of pole figures recorded with divergent-beam geometries, is not necessary when a parallel beam, produced by an X-ray lens, is used. In this case, the major instrumental sources of error stem from the illumination of areas outside the sample surface,i.e.the finite sample size, and the finite area of the detector, both giving rise to a reduction of the recorded signal. Two correction procedures for this reduction, an experimental one and a numerical one, have been tested and are described.

Sign in / Sign up

Export Citation Format

Share Document