Dr. Oliver Bunk
Profil
Forschungsthemen2
FOR 2537/2: "Grammatische Dynamiken im Sprachkontakt: ein komparativer Ansatz" (TP P8)
Quelle ↗Förderer: DFG Forschungsgruppe Zeitraum: 04/2021 - 12/2025 Projektleitung: Dr. Oliver Bunk
SFB 1412/2: Der Einfluss von Sprachideologien auf Registerdifferenzierungen in mehrsprachigen Kontexten (TP C07)
Quelle ↗Förderer: DFG Sonderforschungsbereich Zeitraum: 01/2024 - 12/2027 Projektleitung: Dr. Oliver Bunk, Prof. Dr. Heike Wiese, Dr. Antje Sauermann
Mögliche Industrie-Partner10
Stand: 26.4.2026, 19:48:44 (Top-K=20, Min-Cosine=0.4)
- 86 Treffer58.9%
- Surface-enhanced Raman spectroscopy in liquid biopsy for breast cancerP58.9%
- Surface-enhanced Raman spectroscopy in liquid biopsy for breast cancer
- 88 Treffer58.9%
- Surface-enhanced Raman spectroscopy in liquid biopsy for breast cancerP58.9%
- Surface-enhanced Raman spectroscopy in liquid biopsy for breast cancer
- 145 Treffer58.8%
- Interfaces in opto-electronic thin film multilayer devicesP58.8%
- Interfaces in opto-electronic thin film multilayer devices
- 123 Treffer58.2%
- EU: Scattering Amplitudes: From Geometry to EXperiment (SAGEX)P58.2%
- EU: Scattering Amplitudes: From Geometry to EXperiment (SAGEX)
- 45 Treffer58.2%
- EU: Hybrid Organic/Inorganic Memory Elements for Integration of Electronic and Photonic Circuitry (HYMEC)P58.2%
- EU: Hybrid Organic/Inorganic Memory Elements for Integration of Electronic and Photonic Circuitry (HYMEC)
- 121 Treffer55.4%
- EU: HIgh ACCuracy printed electronics to <1μm, for OLAE TFT and Display Applications (HI-ACCURACY)P55.4%
- WATSON - A holistic frameWork with Anticounterfeit and inTelligence-based technologieS that will assist food chain stakehOlders in rapidly identifying and preveNting the spread of fraudulent practicesP50.3%
- EU: HIgh ACCuracy printed electronics to <1μm, for OLAE TFT and Display Applications (HI-ACCURACY)
- 81 Treffer55.4%
- EU: HIgh ACCuracy printed electronics to <1μm, for OLAE TFT and Display Applications (HI-ACCURACY)P55.4%
- EU: HIgh ACCuracy printed electronics to <1μm, for OLAE TFT and Display Applications (HI-ACCURACY)
- 91 Treffer55.4%
- EU: HIgh ACCuracy printed electronics to <1μm, for OLAE TFT and Display Applications (HI-ACCURACY)P55.4%
- EU: HIgh ACCuracy printed electronics to <1μm, for OLAE TFT and Display Applications (HI-ACCURACY)
Neudrive Limited Leading oft Technology
P91 Treffer55.4%- EU: HIgh ACCuracy printed electronics to <1μm, for OLAE TFT and Display Applications (HI-ACCURACY)P55.4%
- EU: HIgh ACCuracy printed electronics to <1μm, for OLAE TFT and Display Applications (HI-ACCURACY)
- 86 Treffer55.4%
- EU: HIgh ACCuracy printed electronics to <1μm, for OLAE TFT and Display Applications (HI-ACCURACY)P55.4%
- EU: HIgh ACCuracy printed electronics to <1μm, for OLAE TFT and Display Applications (HI-ACCURACY)
Publikationen25
Top 25 nach Zitationen — Quelle: OpenAlex (BAAI/bge-m3 embedded für Matching).
Nature Physics · 1835 Zitationen · DOI
Science · 1298 Zitationen · DOI
Coherent diffractive imaging (CDI) and scanning transmission x-ray microscopy (STXM) are two popular microscopy techniques that have evolved quite independently. CDI promises to reach resolutions below 10 nanometers, but the reconstruction procedures put stringent requirements on data quality and sample preparation. In contrast, STXM features straightforward data analysis, but its resolution is limited by the spot size on the specimen. We demonstrate a ptychographic imaging method that bridges the gap between CDI and STXM by measuring complete diffraction patterns at each point of a STXM scan. The high penetration power of x-rays in combination with the high spatial resolution will allow investigation of a wide range of complex mesoscopic life and material science specimens, such as embedded semiconductor devices or cellular networks.
Nature Materials · 1127 Zitationen · DOI
Nature · 911 Zitationen · DOI
Physical Review Letters · 842 Zitationen · DOI
We demonstrate a hard-x-ray microscope that does not use a lens and is not limited to a small field of view or an object of finite size. The method does not suffer any of the physical constraints, convergence problems, or defocus ambiguities that often arise in conventional phase-retrieval diffractive imaging techniques. Calculation times are about a thousand times shorter than in current iterative algorithms. We need no a priori knowledge about the object, which can be a transmission function with both modulus and phase components. The technique has revolutionary implications for x-ray imaging of all classes of specimen.
Ultramicroscopy · 695 Zitationen · DOI
Nature · 476 Zitationen · DOI
Advanced Materials · 455 Zitationen · DOI
Substituted hexabenzocoronenes (HBCs) form films with supramolecularly ordered columnar stacks that are uniaxially oriented onto poly(tetrafluoroethylene) alignment layers (see Figure). In field‐effect transistor (FET) tests, mobilities of up to 10 –3 cm 2 V –1 s –1 and high on–off ratios of more than 10 4 were derived for these aligned HBC films, characteristics superior to FETs prepared from isotropic HBC layers.
Physical Review Letters · 369 Zitationen · DOI
We report on a method for tomographic phase contrast imaging of centimeter sized objects. As opposed to existing techniques, our approach can be used with low-brilliance, lab based x-ray sources and thus is of interest for a wide range of applications in medicine, biology, and nondestructive testing. The work is based on the recent development of a hard x-ray grating interferometer, which has been demonstrated to yield differential phase contrast projection images. Here we particularly focus on how this method can be used for tomographic reconstructions using filtered back projection algorithms to yield quantitative volumetric information of both the real and imaginary part of the samples's refractive index.
Scientific Reports · 352 Zitationen · DOI
X-ray ptychography is a scanning variant of coherent diffractive imaging with the ability to image large fields of view at high resolution. It further allows imaging of non-isolated specimens and can produce quantitative mapping of the electron density distribution in 3D when combined with computed tomography. The method does not require imaging lenses, which makes it dose efficient and suitable to multi-keV X-rays, where efficient photon counting, pixelated detectors are available. Here we present the first highly resolved quantitative X-ray ptychographic tomography of an extended object yielding 16 nm isotropic 3D resolution recorded at 2 Å wavelength. This first-of-its-kind demonstration paves the way for ptychographic X-ray tomography to become a promising method for X-ray imaging of representative sample volumes at unmatched resolution, opening tremendous potential for characterizing samples in materials science and biology by filling the resolution gap between electron microscopy and other X-ray imaging techniques.
Ultramicroscopy · 307 Zitationen · DOI
Nature · 249 Zitationen · DOI
Physics in Medicine and Biology · 227 Zitationen · DOI
The basic principles of x-ray image formation in radiology have remained essentially unchanged since Röntgen first discovered x-rays over a hundred years ago. The conventional approach relies on x-ray attenuation as the sole source of contrast and draws exclusively on ray or geometrical optics to describe and interpret image formation. Phase-contrast or coherent scatter imaging techniques, which can be understood using wave optics rather than ray optics, offer ways to augment or complement the conventional approach by incorporating the wave-optical interaction of x-rays with the specimen. With a recently developed approach based on x-ray optical gratings, advanced phase-contrast and dark-field scatter imaging modalities are now in reach for routine medical imaging and non-destructive testing applications. To quantitatively assess the new potential of particularly the grating-based dark-field imaging modality, we here introduce a mathematical formalism together with a material-dependent parameter, the so-called linear diffusion coefficient and show that this description can yield quantitative dark-field computed tomography (QDFCT) images of experimental test phantoms.
Physical Review Letters · 224 Zitationen · DOI
We report how a setup consisting of three gratings yields quantitative two- and three-dimensional images depicting the quantum-mechanical phase shifts of neutron de Broglie wave packets induced by the influence of macroscopic objects. Since our approach requires only a little spatial and chromatic coherence it provides a more than 2 orders of magnitude higher efficiency than existing techniques. This dramatically reduces the required measurement time for computed phase tomography and opens up the way for three-dimensional investigations of previously inaccessible quantum-mechanical phase interactions of neutrons with matter.
Optics Express · 218 Zitationen · DOI
Coherent diffractive imaging provides accurate phase projections that can be tomographically combined to yield detailed quantitative 3D reconstructions with a resolution that is not limited by imaging optics. We present robust algorithms for post-processing and alignment of these tomographic phase projections. A simple method to remove undesired constant and linear phase terms on the reconstructions is given. Also, we provide an algorithm for automatic alignment of projections that has good performance even for samples with no fiducial markers. Currently applied to phase projections, this alignment algorithm has proven to be robust and should also be useful for lens-based tomography techniques that pursue nanoscale 3D imaging. Lastly, we provide a method for tomographic reconstruction that works on phase projections that are known modulo 2π, such that the phase unwrapping step is avoided. We demonstrate the performance of these algorithms by 3D imaging of bacteria population in legume root-nodule cells.
Microelectronic Engineering · 218 Zitationen · DOI
A two-directional approach for grating based differential phase contrast imaging using hard x-rays
2007Optics Express · 203 Zitationen · DOI
We report on a two-directional approach for grating based x-ray differential phase contrast imaging. In order to retrieve good quality and artifact-free phase images for quantitative analysis and image processing, particular emphasis is put on the algorithm for proper phase retrieval. Examples of application are discussed that demonstrate the functionality of the method even in cases where the one-dimensional phase integration fails completely.
High-resolution brain tumor visualization using three-dimensional x-ray phase contrast tomography
2007Physics in Medicine and Biology · 201 Zitationen · DOI
We report on significant advances and new results concerning a recently developed method for grating-based hard x-ray phase tomography. We demonstrate how the soft tissue sensitivity of the technique is increased and show in vitro tomographic images of a tumor bearing rat brain sample, without use of contrast agents. In particular, we observe that the brain tumor and the white and gray brain matter structure in a rat's cerebellum are clearly resolved. The results are potentially interesting from a clinical point of view, since a similar approach using three transmission gratings can be implemented with more readily available x-ray sources, such as standard x-ray tubes. Moreover, the results open the way to in vivo experiments in the near future.
Physical review. B, Condensed matter · 190 Zitationen · DOI
A detailed structural model for the indium-induced $\mathrm{Si}(111)\ensuremath{-}(4\ifmmode\times\else\texttimes\fi{}1)$ surface reconstruction has been determined by analyzing an extensive set of x-ray-diffraction data recorded with monochromatic $(\ensuremath{\Elzxh}\ensuremath{\omega}=9.1\mathrm{keV})$ synchrotron radiation. The reconstruction is quasi-one-dimensional. The main features in the structure are chains of silicon atoms alternating with zigzag chains of indium atoms on top of an essentially unperturbed silicon lattice. The indium coverage corresponds to one monolayer. The structural model consistently explains all previously published experimental data.
Optics Express · 186 Zitationen · DOI
We have employed ptychographic coherent diffractive imaging to completely characterize the focal spot wavefield and wavefront aberrations of a high-resolution diffractive X-ray lens. The ptychographic data from a strongly scattering object was acquired using the radiation cone emanating from a coherently illuminated Fresnel zone plate at a photon energy of 6.2 keV. Reconstructed images of the object were retrieved with a spatial resolution of 8 nm by combining the difference-map phase retrieval algorithm with a non-linear optimization refinement. By numerically propagating the reconstructed illumination function, we have obtained the X-ray wavefield profile of the 23 nm round focus of the Fresnel zone plate (outermost zone width, Δr = 20 nm) as well as the X-ray wavefront at the exit pupil of the lens. The measurements of the wavefront aberrations were repeatable to within a root mean square error of 0.006 waves, and we demonstrate that they can be related to manufacturing aspects of the diffractive optical element and to errors on the incident X-ray wavefront introduced by the upstream beamline optics.
Physical Review B · 185 Zitationen · DOI
X-ray ptychographic computed tomography has recently emerged as a nondestructive characterization tool for samples with representative sizes of several tens of micrometers, yet offering a resolution currently lying in but not limited to the 100-nm range. Here we evaluate the quantitativeness of this technique using a model sample with a known structure and density, and we discuss its sensitivity as a function of resolution. Additionally, we show an example application for the determination of the mass density of individual $2\ensuremath{-}\ensuremath{\mu}$m-sized SiO${}_{2}$ microspheres with a relative error of 2$%$. The accuracy and sensitivity demonstrated in this paper will enable quantitative imaging, segmentation, and identification of different phases in complex materials at the nanoscale.
New Journal of Physics · 183 Zitationen · DOI
Applying iterative phase retrieval schemes to ptychographic data, i.e. diffraction patterns collected with a localized illumination probe from overlapping regions of a specimen, has enabled the investigation of extended specimens previously inaccessible by other coherent x-ray diffractive imaging methods. While the technique had initially been limited by the requirement of precise knowledge of the illumination function, recent algorithmic developments allow now the simultaneous reconstruction of both the probe and the object. However, these new approaches suffer from an inherent ambiguity, which affects especially the case of weakly scattering specimens. We present new schemes to circumvent this problem and introduce new tools for obtaining information about the scattering behaviour of weak phase objects already during data collection. The new techniques are experimentally demonstrated for a data set taken on Magnetospirillum gryphiswaldense. Applying iterative phase retrieval schemes to ptychographic data, i.e. diffraction patterns collected with a localized illumination probe from overlapping regions of a specimen, has enabled the investigation of extended specimens previously inaccessible by other coherent x−ray diffractive imaging methods. While the technique had initially been limited by the requirement of precise knowledge of the illumination function, recent algorithmic developments allow now the simultaneous reconstruction of both the probe and the object. However, these new approaches suffer from an inherent ambiguity, which affects especially the case of weakly scattering specimens. We present new schemes to circumvent this problem and introduce new tools for obtaining information about the scattering behaviour of weak phase objects already during data collection. The new techniques are experimentally demonstrated for a data set taken on Magnetospirillum gryphiswaldense
Nature Electronics · 182 Zitationen · DOI
Journal of Applied Physics · 176 Zitationen · DOI
Phase-contrast imaging using conventional polychromatic x-ray sources and grating interferometers has been developed and demonstrated for x-ray energies up to 60 keV. Here, we conduct an analysis of possible grating configurations for this technique and present further geometrical arrangements not considered so far. An inverse interferometer geometry is investigated that offers significant advantages for grating fabrication and for the application of the method in computed tomography (CT) scanners. We derive and measure the interferometer’s angular sensitivity for both the inverse and the conventional configuration as a function of the sample position. Thereby, we show that both arrangements are equally sensitive and that the highest sensitivity is obtained, when the investigated object is close to the interferometer’s phase grating. We also discuss the question whether the sample should be placed in front of or behind the phase grating. For CT applications, we propose an inverse geometry with the sample position behind the phase grating.
Investigative Radiology · 175 Zitationen · DOI
Our results demonstrate the huge potential of phase-contrast CT for clinical investigations of human specimens and, potentially, of humans. Because the applied technique works efficiently with conventional x-ray tubes and detectors, it is suitable for the realization of preclinical and clinical phase-contrast CT systems.
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Stammdaten
Identität, Organisation und Kontakt aus HU-FIS.
- Name
- Dr. Oliver Bunk
- Titel
- Dr.
- Fakultät
- Sprach- und literaturwissenschaftliche Fakultät
- Institut
- Institut für deutsche Sprache und Linguistik
- Arbeitsgruppe
- Sprachwissenschaft des Deutschen, Spracherwerb und Sprachentwicklung in multilingualen Kontexten
- Telefon
- +49 30 2093-85107
- HU-FIS-Profil
- Quelle ↗
- Zuletzt gescrapt
- 26.4.2026, 01:03:25