scholarly journals A convolutional neural network for defect classification in Bragg coherent X-ray diffraction

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Bruce Lim ◽  
Ewen Bellec ◽  
Maxime Dupraz ◽  
Steven Leake ◽  
Andrea Resta ◽  
...  
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Diffraction Pattern ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Coherent Diffraction Imaging ◽  
The Neural Network ◽  
Diffraction Imaging ◽  
Diffraction Patterns ◽  
Defect Recognition

AbstractCoherent diffraction imaging enables the imaging of individual defects, such as dislocations or stacking faults, in materials. These defects and their surrounding elastic strain fields have a critical influence on the macroscopic properties and functionality of materials. However, their identification in Bragg coherent diffraction imaging remains a challenge and requires significant data mining. The ability to identify defects from the diffraction pattern alone would be a significant advantage when targeting specific defect types and accelerates experiment design and execution. Here, we exploit a computational tool based on a three-dimensional (3D) parametric atomistic model and a convolutional neural network to predict dislocations in a crystal from its 3D coherent diffraction pattern. Simulated diffraction patterns from several thousands of relaxed atomistic configurations of nanocrystals are used to train the neural network and to predict the presence or absence of dislocations as well as their type (screw or edge). Our study paves the way for defect-recognition in 3D coherent diffraction patterns for material science.

Incorporating particle symmetry into orientation determination in single-particle imaging

2018 ◽  
Vol 74 (5) ◽  
pp. 512-517
Author(s):  
Miklós Tegze ◽  
Gábor Bortel
Keyword(s):  
Three Dimensional ◽  
Symmetric Case ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coherent Diffraction Imaging ◽  
Diffraction Imaging ◽  
Diffraction Patterns ◽  
Particle Imaging ◽  
Single Particle Imaging ◽  
Orientation Determination

In coherent-diffraction-imaging experiments X-ray diffraction patterns of identical particles are recorded. The particles are injected into the X-ray free-electron laser (XFEL) beam in random orientations. If the particle has symmetry, finding the orientation of a pattern can be ambiguous. With some modifications, the correlation-maximization method can find the relative orientations of the diffraction patterns for the case of symmetric particles as well. After convergence, the correlation maps show the symmetry of the particle and can be used to determine the symmetry elements and their orientations. The C factor, slightly modified for the symmetric case, can indicate the consistency of the assembled three-dimensional intensity distribution.

Quantitative nanotomography of amorphous and polycrystalline samples using coherent X-ray diffraction

2019 ◽  
Vol 52 (3) ◽  
pp. 571-578 ◽  
Author(s):  
Y. Chushkin ◽  
F. Zontone ◽  
O. Cherkas ◽  
A. Gibaud
Keyword(s):  
Mass Density ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coherent Diffraction Imaging ◽  
Diffraction Imaging ◽  
Diffraction Patterns ◽  
Better Than

This article presents a combined approach where quantitative forward-scattering coherent diffraction imaging (CDI) is supported by crystal diffraction using 8.1 keV synchrotron X-ray radiation. The method allows the determination of the morphology, mass density and crystallinity of an isolated microscopic specimen. This approach is tested on three homogeneous samples made of different materials with different degrees of crystallinity. The mass density and morphology are revealed using three-dimensional coherent diffraction imaging with a resolution better than 36 nm. The crystallinity is extracted from the diffraction profiles measured simultaneously with coherent diffraction patterns. The presented approach extends CDI to structural characterization of samples when crystallinity aspects are of interest.

Upsampling speckle patterns for coherent X-ray diffraction imaging

2013 ◽  
Vol 46 (2) ◽  
pp. 319-323 ◽  
Author(s):  
Y. Chushkin ◽  
F. Zontone
Keyword(s):  
Diffraction Pattern ◽  
Imaging Technique ◽  
Real Space ◽  
Field Of View ◽  
Combination Method ◽  
Pixel Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Imaging ◽  
Diffraction Patterns

Coherent X-ray diffraction imaging is a lensless imaging technique where an iterative phase-retrieval algorithm is applied to the speckle pattern, the far-field diffraction pattern produced by an isolated object. To ensure convergence to a unique solution, the diffraction pattern must be oversampled by a factor of two or more. Since the resolution in real space depends on the maximum wave vector where the intensity is detected,i.e.on the detector field of view, there is a practical limitation on oversampling in reciprocal space and resolution in real space that is ultimately determined by the number of pixels. This work shows that it is possible to reduce the effective pixel size and maintain the detector field of view by applying a linear combination method to shifted diffraction patterns. The feasibility of the method is demonstrated by reconstructing the images of test objects from diffraction patterns oversampled in each dimension by factors of 1.3 and 1.8 only. The described approach can be applied to any diffraction or imaging technique where the resolution is compromised by a large pixel size.

Crystal symmetry classification from powder X-ray diffraction patterns using a convolutional neural network

2020 ◽  
Vol 25 ◽  
pp. 101662
Author(s):  
Alexander N. Zaloga ◽  
Vladimir V. Stanovov ◽  
Oksana E. Bezrukova ◽  
Petr S. Dubinin ◽  
Igor S. Yakimov
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Crystal Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Symmetry Classification ◽  
Diffraction Patterns

scholarly journals Bragg–Laue X-ray dynamical diffraction on perfect and deformed lateral crystalline structures

2016 ◽  
Vol 49 (4) ◽  
pp. 1190-1202 ◽  
Author(s):  
Vasily I. Punegov ◽  
Sergey I. Kolosov ◽  
Konstantin M. Pavlov
Keyword(s):  
Cross Sections ◽  
X Ray Diffraction ◽  
Dynamical Diffraction ◽  
X Ray ◽  
Crystalline Structures ◽  
Coherent Diffraction Imaging ◽  
Diffraction Imaging ◽  
Diffraction Patterns ◽  
Lateral Structures ◽  
Laue Geometry

The new dynamical diffraction approach to X-ray diffraction on lateral crystalline structures has been developed to investigate the angular and spatial distribution of wavefields in the case of the Bragg–Laue geometry in non-perfect lateral structures. This approach allows one to calculate reciprocal space maps for deformed lateral crystals having rectangular cross sections for both the transmitted and reflected wavefields. Numerical modelling is performed for crystals with different lateral sizes, thicknesses and deformations. The approach can be used in coherent diffraction imaging to simulate Fraunhofer diffraction patterns produced by relatively large deformed crystals.

Coherent diffraction imaging: consistency of the assembled three-dimensional distribution

2016 ◽  
Vol 72 (4) ◽  
pp. 459-464 ◽  
Author(s):  
Miklós Tegze ◽  
Gábor Bortel
Keyword(s):  
Structural Information ◽  
Three Dimensional ◽  
Atomic Scale ◽  
Short Pulses ◽  
X Ray ◽  
Coherent Diffraction Imaging ◽  
Imaging Experiment ◽  
Dimensional Distribution ◽  
Diffraction Imaging ◽  
Diffraction Patterns

The short pulses of X-ray free-electron lasers can produce diffraction patterns with structural information before radiation damage destroys the particle. From the recorded diffraction patterns the structure of particles or molecules can be determined on the nano- or even atomic scale. In a coherent diffraction imaging experiment thousands of diffraction patterns of identical particles are recorded and assembled into a three-dimensional distribution which is subsequently used to solve the structure of the particle. It is essential to know, but not always obvious, that the assembled three-dimensional reciprocal-space intensity distribution is really consistent with the measured diffraction patterns. This paper shows that, with the use of correlation maps and a single parameter calculated from them, the consistency of the three-dimensional distribution can be reliably validated.

A protocol for searching the most probable phase-retrieved maps in coherent X-ray diffraction imaging by exploiting the relationship between convergence of the retrieved phase and success of calculation

2017 ◽  
Vol 24 (5) ◽  
pp. 1024-1038 ◽  
Author(s):  
Yuki Sekiguchi ◽  
Saki Hashimoto ◽  
Amane Kobayashi ◽  
Tomotaka Oroguchi ◽  
Masayoshi Nakasako
Keyword(s):  
Diffraction Pattern ◽  
Electron Density ◽  
Figure Of Merit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Density Maps ◽  
Diffraction Imaging ◽  
Density Map ◽  
Diffraction Patterns ◽  
Electron Density Map

Coherent X-ray diffraction imaging (CXDI) is a technique for visualizing the structures of non-crystalline particles with size in the submicrometer to micrometer range in material sciences and biology. In the structural analysis of CXDI, the electron density map of a specimen particle projected along the direction of the incident X-rays can be reconstructed only from the diffraction pattern by using phase-retrieval (PR) algorithms. However, in practice, the reconstruction, relying entirely on the computational procedure, sometimes fails because diffraction patterns miss the data in small-angle regions owing to the beam stop and saturation of the detector pixels, and are modified by Poisson noise in X-ray detection. To date, X-ray free-electron lasers have allowed us to collect a large number of diffraction patterns within a short period of time. Therefore, the reconstruction of correct electron density maps is the bottleneck for efficiently conducting structure analyses of non-crystalline particles. To automatically address the correctness of retrieved electron density maps, a data analysis protocol to extract the most probable electron density maps from a set of maps retrieved from 1000 different random seeds for a single diffraction pattern is proposed. Through monitoring the variations of the phase values during PR calculations, the tendency for the PR calculations to succeed when the retrieved phase sets converged on a certain value was found. On the other hand, if the phase set was in persistent variation, the PR calculation tended to fail to yield the correct electron density map. To quantify this tendency, here a figure of merit for the variation of the phase values during PR calculation is introduced. In addition, a PR protocol to evaluate the similarity between a map of the highest figure of merit and other independently reconstructed maps is proposed. The protocol is implemented and practically examined in the structure analyses for diffraction patterns from aggregates of gold colloidal particles. Furthermore, the feasibility of the protocol in the structure analysis of organelles from biological cells is examined.

A multiple-common-lines method to determine the orientation of snapshot diffraction patterns from single particles

2014 ◽  
Vol 70 (4) ◽  
pp. 364-372 ◽  
Author(s):  
Liang Zhou ◽  
Tian-Yi Zhang ◽  
Zhong-Chuan Liu ◽  
Peng Liu ◽  
Yu-Hui Dong
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
Single Particles ◽  
X Ray ◽  
Three Dimensional Structure ◽  
Individual Object ◽  
Common Lines ◽  
Diffraction Imaging ◽  
Diffraction Patterns

With the development of X-ray free-electron lasers (XFELs), it is possible to determine the three-dimensional structures of noncrystalline objects with coherent X-ray diffraction imaging. In this diffract-and-destroy mode, many snapshot diffraction patterns are obtained from the identical objects which are presented one by one in random orientations to the XFEL beam. Determination of the orientation of an individual object is essential for reconstruction of a three-dimensional structure. Here a new method, called the multiple-common-lines method, has been proposed to determine the orientations of high- and low-signal snapshot diffraction patterns. The mean errors of recovered orientations (α, β, γ) of high- and low-signal patterns are about 0.14, 0.06, 0.12 and 0.77, 0.31, 0.60°, respectively; both sets of errors can meet the requirements of the reconstruction of a three-dimensional structure.

scholarly journals Micro-beam Laue alignment of multi-reflection Bragg coherent diffraction imaging measurements

2017 ◽  
Vol 24 (5) ◽  
pp. 1048-1055 ◽  
Author(s):  
Felix Hofmann ◽  
Nicholas W. Phillips ◽  
Ross J. Harder ◽  
Wenjun Liu ◽  
Jesse N. Clark ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Lattice Strain ◽  
Ion Beam ◽  
Strain Tensor ◽  
Three Dimensional ◽  
Stress Fields ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coherent Diffraction Imaging ◽  
Diffraction Imaging

Multi-reflection Bragg coherent diffraction imaging has the potential to allow three-dimensional (3D) resolved measurements of the full lattice strain tensor in specific micro-crystals. Until now such measurements were hampered by the need for laborious, time-intensive alignment procedures. Here a different approach is demonstrated, using micro-beam Laue X-ray diffraction to first determine the lattice orientation of the micro-crystal. This information is then used to rapidly align coherent diffraction measurements of three or more reflections from the crystal. Based on these, 3D strain and stress fields in the crystal are successfully determined. This approach is demonstrated on a focused ion beam milled micro-crystal from which six reflections could be measured. Since information from more than three independent reflections is available, the reliability of the phases retrieved from the coherent diffraction data can be assessed. Our results show that rapid, reliable 3D coherent diffraction measurements of the full lattice strain tensor in specific micro-crystals are now feasible and can be successfully carried out even in heavily distorted samples.

Sign in / Sign up

Export Citation Format

Share Document