Short-range order in mesoscale systems probed by X-ray grating interferometry

Prade, Friedrich; Yaroshenko, Andre; Herzen, Julia; Pfeiffer, Franz

doi:10.1209/0295-5075/112/68002

Cited by 59 publications

(56 citation statements)

References 30 publications

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“…This direction of future work also lends itself to an investigation into the optimum illumination pattern period to be sensitive to a given dark-field signal for a given wavelength with a given imaging set-up. This links to the correlation length, λ ∆/p seen in grating interferometry 38 , which matches the expression seen when the 'smear width' L is set to the illumination period p, zeroing the visibility of the resulting illumination at the detector (also see Fig. 3 c) of the companion paper on the X-ray Fokker-Planck equation 24 ).…”

Section: Discussionsupporting

confidence: 58%

Applying the Fokker–Planck equation to grating-based x-ray phase and dark-field imaging

Morgan

Paganin

2019

Sci Rep

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X-ray imaging has conventionally relied upon attenuation to provide contrast. In recent years, two complementary modalities have been added; (a) phase contrast, which can capture low-density samples that are difficult to see using attenuation, and (b) dark-field x-ray imaging, which reveals the presence of sub-pixel sample structures. These three modalities can be accessed using a crystal analyser, a grating interferometer or by looking at a directly-resolved grid, grating or speckle pattern. Grating and grid-based methods extract a differential phase signal by measuring how far a feature in the illumination has been shifted transversely due to the presence of a sample. The dark-field signal is extracted by measuring how the visibility of the structured illumination is decreased, typically due to the presence of sub-pixel structures in a sample. The strength of the dark-field signal may depend on the grating period, the pixel size and the set-up distances, and additional dark-field signal contributions may be seen as a result of strong phase effects or other factors. In this paper we show that the finite-difference form of the Fokker–Planck equation can be applied to describe the drift (phase signal) and diffusion (dark-field signal) of the periodic or structured illumination used in phase contrast x-ray imaging with gratings, in order to better understand any cross-talk between attenuation, phase and dark-field x-ray signals. In future work, this mathematical description could be used as a basis for new approaches to the inverse problem of recovering both phase and dark-field information.

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Section: Discussionsupporting

confidence: 58%

Applying the Fokker–Planck equation to grating-based x-ray phase and dark-field imaging

Morgan

Paganin

2019

Sci Rep

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“…It should be mentioned that the absolute sensitivity for the short distance is lower than that for the large distance. As consequence, smaller structures remain visible for an increase in detector distance, as seen earlier [39][40][41] . Large structures only appear with the larger distance.…”

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confidence: 54%

Scalable, large area compound array refractive lens for hard X-rays

Reich

Rolo

Letzel

et al. 2018

Applied Physics Letters

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We demonstrate the fabrication of a 2D Compound Array Refractive Lens (CARL) for multi-contrast X-ray imaging. The CARL consists of six stacked polyimide foils with each displaying a 2D array of lenses with a 65 µm pitch aiming for a sensitivity on sub-micrometer structures with a (few-)micrometer resolution in sensing through phase and scattering contrast at multiple keV. The parabolic lenses are formed by indents in the foils by a paraboloid needle. The ability for fast single-exposure multi-contrast imaging is demonstrated by filming the kinetics of pulsed laser ablation in liquid. The three contrast channels: absorption, differential phase and scattering are imaged with a time resolution of 25 µs. By changing the sample-detector distance it is possible to distinguish between nanoparticles and microbubbles, respectively.

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“…where t is sample thickness, G(ξ) is a pair-correlation function describing scattering, and Σ describes scatterer features such as volume fraction, density contrast, and radius for a two-phase system [7,[21][22][23][24].…”

Section: Dark-field Imagementioning

confidence: 99%

Neutron Imaging of Laser Melted SS316 Test Objects with Spatially Resolved Small Angle Neutron Scattering

et al. 2017

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Abstract:A novel neutron far field interferometer is explored for sub-micron porosity detection in laser sintered stainless steel alloy 316 (SS316) test objects. The results shown are images and volumes of the first quantitative neutron dark-field tomography at various autocorrelation lengths, ξ. In this preliminary work, the beam defining slits were adjusted to an uncalibrated opening of 0.5 mm horizontal and 5 cm vertical; the images are blurred along the vertical direction. In spite of the blurred attenuation images, the dark-field images reveal structural information at the micron-scale. The topics explored include: the accessible size range of defects, potentially 338 nm to 4.5 µm, that can be imaged with the small angle scattering images; the spatial resolution of the attenuation image; the maximum sample dimensions compatible with interferometry optics and neutron attenuation; the procedure for reduction of the raw interferogram images into attenuation, differential phase contrast, and small angle scattering (dark-field) images; and the role of neutron far field interferometry in additive manufacturing to assess sub-micron porosity.

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Short-range order in mesoscale systems probed by X-ray grating interferometry

Cited by 59 publications

References 30 publications

Applying the Fokker–Planck equation to grating-based x-ray phase and dark-field imaging

Applying the Fokker–Planck equation to grating-based x-ray phase and dark-field imaging

Scalable, large area compound array refractive lens for hard X-rays

Neutron Imaging of Laser Melted SS316 Test Objects with Spatially Resolved Small Angle Neutron Scattering

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