Improved Reconstruction Technique for Moiré Imaging Using an X-Ray Phase-Contrast Talbot–Lau Interferometer

Seifert, Maria; Gallersdörfer, Michael; Ludwig, Veronika; Schuster, Max; Horn, Florian; Pelzer, Georg; Rieger, Jens; Michel, Thilo; Anton, G.

doi:10.3390/jimaging4050062

Cited by 16 publications

(21 citation statements)

References 41 publications

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“…While for XST this spatial resolution is linked to the speckle size, which has to be carefully adjusted, the improved image reconstruction by Seifert et al, from moiré patterns yields a relatively homogeneous resolving power. Distortions of the patterns caused by bent gratings are compensated for by their improved data processing chain [9].…”

Section: Data Methods and Resultsmentioning

confidence: 99%

Phase-Contrast and Dark-Field Imaging

Zabler¹

2018

J. Imaging

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Very early, in 1896, Wilhelm Conrad Röntgen, the founding father of X-rays, attempted to measure diffraction and refraction by this new kind of radiation, in vain. Only 70 years later, these effects were measured by Ulrich Bonse and Michael Hart who used them to make full-field images of biological specimen, coining the term phase-contrast imaging. Yet, another 30 years passed until the Talbot effect was rediscovered for X-radiation, giving rise to a micrograting based interferometer, replacing the Bonse–Hart interferometer, which relied on a set of four Laue-crystals for beam splitting and interference. By merging the Lau-interferometer with this Talbot-interferometer, another ten years later, measuring X-ray refraction and X-ray scattering full-field and in cm-sized objects (as Röntgen had attempted 110 years earlier) became feasible in every X-ray laboratory around the world. Today, now that another twelve years have passed and we are approaching the 125th jubilee of Röntgen’s discovery, neither Laue-crystals nor microgratings are a necessity for sensing refraction and scattering by X-rays. Cardboard, steel wool, and sandpaper are sufficient for extracting these contrasts from transmission images, using the latest image reconstruction algorithms. This advancement and the ever rising number of applications for phase-contrast and dark-field imaging prove to what degree our understanding of imaging physics as well as signal processing have advanced since the advent of X-ray physics, in particular during the past two decades. The discovery of the electron, as well as the development of electron imaging technology, has accompanied X-ray physics closely along its path, both modalities exploring the applications of new dark-field contrast mechanisms these days. Materials science, life science, archeology, non-destructive testing, and medicine are the key faculties which have already integrated these new imaging devices, using their contrast mechanisms in full. This special issue “Phase-Contrast and Dark-field Imaging” gives us a broad yet very to-the-point glimpse of research and development which are currently taking place in this very active field. We find reviews, applications reports, and methodological papers of very high quality from various groups, most of which operate X-ray scanners which comprise these new imaging modalities.

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Section: Data Methods and Resultsmentioning

confidence: 99%

Phase-Contrast and Dark-Field Imaging

Zabler¹

2018

J. Imaging

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“…In Fourier space, the Moiré pattern can be separated from the object structures [ 33 ]. The separated information can be processed to three image modalities [ 32 , 34 , 35 ], the transmission image, the differential phase image and the darkfield image. To reconstruct these images, a reference image is required, i.e., an additional measurement with only the gratings in the beam path and no other object.…”

Section: Methodsmentioning

confidence: 99%

Noise Reduction for Single-Shot Grating-Based Phase-Contrast Imaging at an X-ray Backlighter

et al. 2021

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X-ray backlighters allow the capture of sharp images of fast dynamic processes due to extremely short exposure times. Moiré imaging enables simultaneously measuring the absorption and differential phase-contrast (DPC) of these processes. Acquiring images with one single shot limits the X-ray photon flux, which can result in noisy images. Increasing the photon statistics by repeating the experiment to gain the same image is not possible if the investigated processes are dynamic and chaotic. Furthermore, to reconstruct the DPC and transmission image, an additional measurement captured in absence of the object is required. For these reference measurements, shot-to-shot fluctuations in X-ray spectra and a source position complicate the averaging of several reference images for noise reduction. Here, two approaches of processing multiple reference imagesin combination with one single object image are evaluated regarding the image quality. We found that with only five reference images, the contrast-to-noise ratio can be improved by approximately 13% in the DPC image. This promises improvements for short-exposure single-shot acquisitions of rapid processes, such as laser-produced plasma shock-waves in high-energy density experiments at backlighter X-ray sources such as the PHELIX high-power laser facility.

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“…There are single shot approaches, [7][8][9][10][11] which render phase, scattering, and attenuation data from single projection measurements without mechanical phase stepping measurements at each projections angle. The challenges of mechanical phase stepping are the need to obtain precise grating positing at multiple measurements per projection angle, whereas single shot approaches of data acquisition have shorter acquisition times and have better mechanical stability.…”

Section: A3 Advantages Of Single Shot Approachesmentioning

confidence: 99%

X‐ray bi‐prism interferometry—A design study of proposed novel hardware

et al. 2021

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Purpose: Advances in X-ray phase-contrast imaging can obtain excellent soft-tissue contrast of phase-shift, attenuation, and small angle scatter. Here we present fringe patterns for different design parameters of Xray bi-prism interferometry imaging systems. Our aim is to develop bi-prism interferometry imaging systems with excellent polychromatic performance that produce high-contrast fringes with spatially incoherent X-ray illumination. We also introduce a novel X-ray tube design that uses temporal multiplexing to provide simultaneous virtual "electronic phase stepping" that replace "mechanical phase stepping" popular with grating-based interferometry setups. Methods:In our investigation we develop expressions for the irradiance distribution pattern of a bi-prism interferometer comprised of multiple point sources and multiple bi-prisms. These expressions are used to plot fringe patterns for X-ray design parameters including size of point source, number of point sources, and point source separation; and bi-prism design parameters including material, angle, number of biprisms, period, and bi-prism array to X-ray source and to detector distances. Results:Results show that the fringe patterns for a bi-prism interferometry system are not longitudinally periodic as with grating interferometers that produce a Talbot-Lau carpet. It is also shown that at 59 keV Xrays the bi-prism material should be something comparable to nickel to obtain reasonable fringe visibility. Conclusion:The irradiance distribution pattern demonstrates that bi-prism interferometry may provide comparable or improved fringe visibility to that of gratings. Special care is given to present our findings within the context of previous advancements. A single-shot image acquisition approach using a temporal multiplexed, high-power X-ray source provides virtual electronic phase stepping without focal spot sweeping. This provides multiple images, each at the same exposure and the same projection view, from different fringe locations that allow one to derive the attenuation, phase, and dark-field images of the sample without mechanical phase stepping of a grating.

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Improved Reconstruction Technique for Moiré Imaging Using an X-Ray Phase-Contrast Talbot–Lau Interferometer

Cited by 16 publications

References 41 publications

Phase-Contrast and Dark-Field Imaging

Phase-Contrast and Dark-Field Imaging

Noise Reduction for Single-Shot Grating-Based Phase-Contrast Imaging at an X-ray Backlighter

X‐ray bi‐prism interferometry—A design study of proposed novel hardware

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