Interpretation of dark-field contrast and particle-size selectivity in grating interferometers

Lynch, Susanna K.; Pai, Vinay; Auxier, Julie A.; Stein, Ashley; Bennett, Eric E.; Kemble, Camille K.; Xiao, Xianghui; Lee, Ivan; Morgan, Nicole Y.; Wen, Han

doi:10.1364/ao.50.004310

Cited by 178 publications

(245 citation statements)

References 24 publications

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“…To define the DFI sensitivity to different structure sizes, it has been proposed to use diluted spherical particles as reference material (Lynch et al, 2011). Although, the DFI contrast might be slightly different for arbitrarily shaped microstructures, this referencing has general significance for diluted systems.…”

Section: The Sensitivity Of the Dfi To Structures Of Different Sizesmentioning

confidence: 99%

The new neutron grating interferometer at the ANTARES beamline: design, principles and applications

et al. 2016

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neutron radiography; neutron imaging; neutron grating interferometry; neutron dark-field imaging; small-angle neutron scattering; ultra-small-angle neutron scattering AbstractNeutron grating interferometry is an advanced method in neutron imaging that allows the simultaneous recording of the transmission, the differential phase and the darkfield image. Especially the latter has recently received high interest because of its unique contrast mechanism which marks ultra-small-angle neutron scattering within the sample. Hence, in neutron grating interferometry, an imaging contrast is generated by scattering of neutrons off micrometer-sized inhomogeneities. Although the scatterer cannot be resolved it leads to a measurable local decoherence of the beam. Here, a arXiv:1602.08846v1 [cond-mat.mtrl-sci] 29 Feb 2016 2 report is given on the design considerations, principles and applications of a new neutron grating interferometer which has recently been implemented at the ANTARES beamline at the Heinz Maier-Leibnitz Zentrum. Its highly flexible design allows to perform experiments such as directional and quantitative dark-field imaging which provide spatially resolved information on the anisotropy and shape of the microstructure of the sample. A comprehensive overview of the nGI principle is given, followed by theoretical considerations to optimize the setup performance for different applications.Furthermore, an extensive characterization of the setup is presented and its abilities are demonstrated on selected case studies: (i) dark-field imaging for material differentiation, (ii) directional dark-field imaging to mark and quantify micrometer anisotropies within the sample and (iii) quantitative dark-field imaging, providing additional size information on the sample's microstructure by probing its autocorrelation function.

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Section: The Sensitivity Of the Dfi To Structures Of Different Sizesmentioning

confidence: 99%

The new neutron grating interferometer at the ANTARES beamline: design, principles and applications

et al. 2016

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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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“…The darkfield signal can reveal structural information about the unresolved microstructure of the sample in a size scale beyond the resolution capabilities of the detecting system. 15,16 The usual realisation of a GI is the Talbot-Lau interferometer consisting of three gratings G 0 , G 1 and G 2 . 17 The first grating G 0 (absorption grating) is optionally used to generate enough spatial coherence when X-ray sources with a large focal size are used.…”

mentioning

confidence: 99%

“…19,20 Moreover, for the investigation of unresolved microstructures by means of the dark-field signal multiple measurements at different correlation lengths need to be performed. 15,16,21 The correlation length n basically depends on three factors: wavelength k, sample to detector distance L s , and the period of the interference fringe p. The proposed methods so far focus on moving the sample between the detector and the phase grating G 1 in order to scan at different correlation lengths. 21,22 Nonetheless, such an approach has a number of limitations.…”

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confidence: 99%

Dual phase grating interferometer for tunable dark-field sensitivity

Kagias

Wang

Jefimovs

et al. 2017

Applied Physics Letters

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Hard X-ray dark-field and phase contrast imaging using grating interferometry have shown great potential for medical and industrial applications. However, the wide spread applicability of the method is challenged by a number of technical related issues such as relatively low dose and flux efficiency due to the absorption grating, fabrication of high quality absorption gratings, slow data acquisition protocol and high mechanical stability requirements. In this paper, the authors propose an interferometric method for dark-field and differential phase contrast imaging based on phase shifting elements only with the purpose to improve the dose and flux efficiency and simplify the setup. The proposed interferometer consists of two identical phase gratings of small pitch (1.3 μm), which generate an interference fringe at the detector plane with a large enough pitch that can be resolved directly. In particular, the system exhibits flexible and tunable dark-field sensitivity which is advantageous to probe unresolvable micro-structure in the sample. Experiments on a micro focal tube validated the method and demonstrated the versatility and tunability of the system compared to conventional Talbot grating interferometer.

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Interpretation of dark-field contrast and particle-size selectivity in grating interferometers

Cited by 178 publications

References 24 publications

The new neutron grating interferometer at the ANTARES beamline: design, principles and applications

The new neutron grating interferometer at the ANTARES beamline: design, principles and applications

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

Dual phase grating interferometer for tunable dark-field sensitivity

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