scholarly journals Modeling the Moiré fringe visibility of Talbot-Lau X-ray grating interferometry for single-frame multi-contrast imaging

2020 ◽  
Vol 28 (18) ◽  
pp. 27107
Author(s):  
Kai Deng ◽  
Jing Li ◽  
Weiping Xie
Keyword(s):  
Contrast Imaging ◽  
Fringe Visibility ◽  
X Ray ◽  
Single Frame ◽  
Moire Fringe ◽  
Moiré Fringe

Quantitative Calculation of Fringe Visibility in Bismuth Grating-Based X-Ray Phase-Contrast Imaging

2017 ◽  
Vol 37 (4) ◽  
pp. 0434001
Author(s):  
黄建衡 Huang Jianheng ◽  
雷耀虎 Lei Yaohu ◽  
杜杨 Du Yang ◽  
刘鑫 Liu Xin ◽  
郭金川 Guo Jinchuan ◽  
...  
Keyword(s):  
Phase Contrast ◽  
Phase Contrast Imaging ◽  
Contrast Imaging ◽  
Fringe Visibility ◽  
X Ray ◽  
Quantitative Calculation

Quantitative analysis of fringe visibility in grating-based x-ray phase-contrast imaging

2015 ◽  
Vol 33 (1) ◽  
pp. 69
Author(s):  
Jianheng Huang ◽  
Yaohu Lei ◽  
Yang Du ◽  
Xin Liu ◽  
Jinchuan Guo ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Phase Contrast ◽  
Phase Contrast Imaging ◽  
Contrast Imaging ◽  
Fringe Visibility ◽  
X Ray

Development of the Child's Arch

Foot & Ankle ◽  
1989 ◽  
Vol 9 (5) ◽  
pp. 241-245 ◽  
Author(s):  
Nathaniel Gould ◽  
Morey Moreland ◽  
Richard Alvarez ◽  
Saul Trevino ◽  
James Fenwick
Keyword(s):  
Lower Extremities ◽  
Genu Valgum ◽  
Initial Examination ◽  
Pes Planus ◽  
X Ray ◽  
Longitudinal Arch ◽  
Physical Examinations ◽  
Moire Fringe ◽  
Arch Support ◽  
Moiré Fringe

The purposes of the project were to monitor the development of the lower extremities and the longitudinal arch of the foot and to determine whether or not arch support footwear (three types) affected development of a neutral arch in toddlers 11 to 14 months of age until age 5 years. A total of 125 beginner walkers were recruited through the pediatrics department during a period of 1 ½ years and divided by lot into four different footwear groups (one nonarch supportive). The group was studied for 4 years by physical examinations, x-ray films, and pedotopography (a Moire fringe technique of photography). At initial examination all of the apparently normal toddlers had pes planus by all clinical, roentgenographic, and photographic measurements. There were no cavus feet at that time or at 5 years of age. Arches developed regardless of the footwear worn but development was faster during the first 2 years (until age 3 years) with arch support footwear. The rapidity of arch development until 5 years of age continued in those children who wore longitudinal arch cookies. Ossification of the sustentaculum tali begins at approximately 5 years of age but is not complete for at least another 1 to 2 years. Hyperpronation was present in 77.9% and genu valgum in 92.3% of the 5-year-old children. These conditions are apparently the norm at this age in both boys and girls.

scholarly journals Tomography of dark‐field scatter including single‐exposure Moiré fringe analysis with X‐ray biprism interferometry—A simulation study

2021 ◽  
Author(s):  
Weijie Tao ◽  
Yongjin Sung ◽  
Sally Ji Who Kim ◽  
Qiu Huang ◽  
Grant T. Gullberg ◽  
...  
Keyword(s):  
Simulation Study ◽  
Dark Field ◽  
Fringe Analysis ◽  
Single Exposure ◽  
X Ray ◽  
Moire Fringe ◽  
Moiré Fringe

scholarly journals Theoretical study of the properties of X-ray diffraction moiré fringes. III. Theoretical simulation of previous experimental moiré images

2020 ◽  
Vol 76 (4) ◽  
pp. 503-520
Author(s):  
Jun-ichi Yoshimura
Keyword(s):  
Local Strain ◽  
Theoretical Explanation ◽  
Global Features ◽  
Acta Cryst ◽  
Theoretical Simulation ◽  
X Ray ◽  
Moire Fringe ◽  
Lattice Planes ◽  
Moiré Fringe ◽  
Fringe Patterns

As a practical confirmation of a recently published X-ray moiré-fringe theory [Yoshimura (2015). Acta Cryst. A71, 368–381], computer simulations using this theory were conducted for previous experimental moiré images of a strained bicrystal specimen [Yoshimura (1996). Acta Cryst. A52, 312–325]. Simulated moiré images with a good or fairly good likeness are presented as a result of this simulation, in which the characteristic fringe-and-band and local strain patterns in the experimental images are reproduced well. Experimental moiré images taken when the inclination of the lattice planes was forcedly increased in one of the component crystals of the bicrystal specimen were also fairly well simulated in this computation, and their fringe patterns of inclined fringes are shown to be in accordance with the prediction by the theory. This moiré-fringe theory is thus considered to be widely applicable to the study of moiré images. Furthermore, the successful simulation of the previous experimental moiré images means that a satisfactory theoretical explanation was given for the experimental images, with respect to their characteristic global features. However, this study by the theoretical simulation shows explicitly that some significant peculiarities in the fringe profiles of the experimental images still remain unexplained by this moiré-fringe theory.

The CM120 Biotwin: a high-contrast objective lens, optimum cryo-vacuum and improved EDX performance

1995 ◽  
Vol 53 ◽  
pp. 584-585
Author(s):  
Uwe Lücken ◽  
Michael Felsmann ◽  
Wim M. Busing ◽  
Frank de Jong
Keyword(s):  
Life Science ◽  
Focal Length ◽  
Objective Lens ◽  
High Contrast ◽  
Contrast Imaging ◽  
X Ray ◽  
Forming Mechanism ◽  
Similar Image ◽  
High Contrast Imaging ◽  
Low Concentrations

A new microscope for the study of life science specimen has been developed. Special attention has been given to the problems of unstained samples, cryo-specimens and x-ray analysis at low concentrations.A new objective lens with a Cs of 6.2 mm and a focal length of 5.9 mm for high-contrast imaging has been developed. The contrast of a TWIN lens (f = 2.8 mm, Cs = 2 mm) and the BioTWTN are compared at the level of mean and SD of slow scan CCD images. Figure 1a shows 500 +/- 150 and Fig. 1b only 500 +/- 40 counts/pixel. The contrast-forming mechanism for amplitude contrast is dependent on the wavelength, the objective aperture and the focal length. For similar image conditions (same voltage, same objective aperture) the BioTWIN shows more than double the contrast of the TWIN lens. For phasecontrast specimens (like thin frozen-hydrated films) the contrast at Scherzer focus is approximately proportional to the √ Cs.

Simulation and Contrast Analysis of tem Images of Cracks

1990 ◽  
Vol 48 (1) ◽  
pp. 578-579
Author(s):  
D. Goyal ◽  
A. H. King
Keyword(s):  
Displacement Vector ◽  
Crack Tip ◽  
Perfect Crystal ◽  
Operating Conditions ◽  
Displacement Fields ◽  
Fringe Contrast ◽  
Orthogonal Geometry ◽  
Moire Fringe ◽  
Moiré Fringe

TEM images of cracks have been found to give rise to a moiré fringe type of contrast. It is apparent that the moire fringe contrast is observed because of the presence of a fault in a perfect crystal, and is characteristic of the fault geometry and the diffracting conditions in the TEM. Various studies have reported that the moire fringe contrast observed due to the presence of a crack in an otherwise perfect crystal is distinctive of the mode of crack. This paper describes a technique to study the geometry and mode of the cracks by comparing the images they produce in the TEM because of the effect that their displacement fields have on the diffraction of electrons by the crystal (containing a crack) with the corresponding theoretical images. In order to formulate a means of matching experimental images with theoretical ones, displacement fields of dislocations present (if any) in the vicinity of the crack are not considered, only the effect of the displacement field of the crack is considered.The theoretical images are obtained using a computer program based on the two beam approximation of the dynamical theory of diffraction contrast for an imperfect crystal. The procedures for the determination of the various parameters involved in these computations have been well documented. There are three basic modes of crack. Preliminary studies were carried out considering the simplest form of crack geometries, i. e., mode I, II, III and the mixed modes, with orthogonal crack geometries. It was found that the contrast obtained from each mode is very distinct. The effect of variation of operating conditions such as diffracting vector (), the deviation parameter (ω), the electron beam direction () and the displacement vector were studied. It has been found that any small change in the above parameters can result in a drastic change in the contrast. The most important parameter for the matching of the theoretical and the experimental images was found to be the determination of the geometry of the crack under consideration. In order to be able to simulate the crack image shown in Figure 1, the crack geometry was modified from a orthogonal geometry to one with a crack tip inclined to the original crack front. The variation in the crack tip direction resulted in the variation of the displacement vector also. Figure 1 is a cross-sectional micrograph of a silicon wafer with a chromium film on top, showing a crack in the silicon.

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