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Optimization of phase contrast imaging with a nano-focus x-ray tube

Dierks, Hanna LU ; Dreier, Till LU orcid ; Kruger, Robin ; Bech, Martin LU orcid and Wallentin, Jesper LU (2023) In Applied Optics 62(20). p.5502-5507
Abstract

Propagation-based phase contrast imaging with a laboratory x-ray source is a valuable tool for studying samples that show only low absorption contrast, either because of low density, elemental composition, or small feature size. If a propagation distance between sample and detector is introduced and the illumination is sufficiently coherent, the phase shift in the sample will cause additional contrast around interfaces, known as edge enhancement fringes. The strength of this effect depends not only on sample parameters and energy but also on the experimental geometry, which can be optimized accordingly. Recently, x-ray lab sources using transmission targets have become available, which provide very small source sizes in the few hundred... (More)

Propagation-based phase contrast imaging with a laboratory x-ray source is a valuable tool for studying samples that show only low absorption contrast, either because of low density, elemental composition, or small feature size. If a propagation distance between sample and detector is introduced and the illumination is sufficiently coherent, the phase shift in the sample will cause additional contrast around interfaces, known as edge enhancement fringes. The strength of this effect depends not only on sample parameters and energy but also on the experimental geometry, which can be optimized accordingly. Recently, x-ray lab sources using transmission targets have become available, which provide very small source sizes in the few hundred nanometer range. This allows the use of a high-magnification geometry with a very short source-sample distance, while still achieving sufficient spatial coherence at the sample position. Moreover, the high geometrical magnification makes it possible to use detectors with a larger pixel size without reducing the image resolution. Here, we explore the influence of magnification on the edge enhancement fringes in such a geometry. We find experimentally and theoretically that the fringes become maximal at a magnification that is independent of the total source-detector distance. This optimal magnification only depends on the source size, the steepness of the sample feature, and the detector resolution. A stronger influence of the sample feature on the optimal magnification compared to low-magnification geometries is observed.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Applied Optics
volume
62
issue
20
pages
6 pages
publisher
Optical Society of America
external identifiers
  • pmid:37706868
  • scopus:85166465083
ISSN
1559-128X
DOI
10.1364/AO.491669
language
English
LU publication?
yes
additional info
Publisher Copyright: Journal © 2023 Optica Publishing Group.
id
4b1da1d8-6f9e-47bc-b51c-085912d47685
date added to LUP
2023-08-12 15:26:09
date last changed
2024-04-20 00:28:04
@article{4b1da1d8-6f9e-47bc-b51c-085912d47685,
  abstract     = {{<p>Propagation-based phase contrast imaging with a laboratory x-ray source is a valuable tool for studying samples that show only low absorption contrast, either because of low density, elemental composition, or small feature size. If a propagation distance between sample and detector is introduced and the illumination is sufficiently coherent, the phase shift in the sample will cause additional contrast around interfaces, known as edge enhancement fringes. The strength of this effect depends not only on sample parameters and energy but also on the experimental geometry, which can be optimized accordingly. Recently, x-ray lab sources using transmission targets have become available, which provide very small source sizes in the few hundred nanometer range. This allows the use of a high-magnification geometry with a very short source-sample distance, while still achieving sufficient spatial coherence at the sample position. Moreover, the high geometrical magnification makes it possible to use detectors with a larger pixel size without reducing the image resolution. Here, we explore the influence of magnification on the edge enhancement fringes in such a geometry. We find experimentally and theoretically that the fringes become maximal at a magnification that is independent of the total source-detector distance. This optimal magnification only depends on the source size, the steepness of the sample feature, and the detector resolution. A stronger influence of the sample feature on the optimal magnification compared to low-magnification geometries is observed.</p>}},
  author       = {{Dierks, Hanna and Dreier, Till and Kruger, Robin and Bech, Martin and Wallentin, Jesper}},
  issn         = {{1559-128X}},
  language     = {{eng}},
  number       = {{20}},
  pages        = {{5502--5507}},
  publisher    = {{Optical Society of America}},
  series       = {{Applied Optics}},
  title        = {{Optimization of phase contrast imaging with a nano-focus x-ray tube}},
  url          = {{http://dx.doi.org/10.1364/AO.491669}},
  doi          = {{10.1364/AO.491669}},
  volume       = {{62}},
  year         = {{2023}},
}