TY - JOUR A1 - Rack, A. A1 - Zabler, S. A1 - Müller, Bernd R. A1 - Riesemeier, Heinrich A1 - Weidemann, Gerd A1 - Lange, Axel A1 - Goebbels, Jürgen A1 - Hentschel, Manfred P. A1 - Görner, Wolf T1 - High resolution synchrotron-based radiography and tomography using hard X-rays at the BAMline (BESSY II) N2 - The use of high brilliance and partial coherent synchrotron light for radiography and computed tomography (CT) allows to image micro-structured, multi-component specimens with different contrast modes and resolutions up to submicrometer range. This is of high interest for materials research, life science and non-destructive evaluation applications. An imaging setup for microtomography and radiography installed at BESSY II (a third generation synchrotron light source located in Berlin, Germany) as part of its first hard X-ray beamline (BAMline) can now be used for absorption, refraction as well as phase contrast — dedicated to inhouse research and applications by external users. Monochromatic synchrotron light between 6 keV and 80 keV is attained via a fully automated double multilayer monochromator. For imaging applications the synchrotron beam transmitted by the sample is converted with a scintillator into visible light. By use of microscope optics this luminescence image is then projected onto, e.g., a CCD chip. Several scintillating materials are used in order to optimise the performance of the detector system. Different optical systems are available for imaging ranging from a larger field of view and moderate resolutions (macroscope — up to 14 mm x 14 mm field of view) to high resolution (microscope — down to 0.35 μm pixel size), offering magnifications from 1.8× to 40×. Additionally asymmetric cut Bragg crystals in front of the scintillator can be used for a further magnification in one dimension by a factor of about 20. Slow and fast cameras are available, with up to 16 bit dynamic range. We show the suitability of the setup for numerous applications from materials research and life science. KW - Microtomography KW - Non-destructive evaluation KW - Synchrotron instrumentation KW - Coherent imaging KW - X-ray refraction KW - Phase contrast KW - Holotomography KW - Synchrotron-CT KW - Scintillator KW - Bragg magnification PY - 2008 DO - https://doi.org/10.1016/j.nima.2007.11.020 SN - 0168-9002 SN - 0167-5087 VL - 586 IS - 2 SP - 327 EP - 344 PB - North-Holland CY - Amsterdam AN - OPUS4-17738 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lange, Axel A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Hentschel, Manfred P. T1 - Edge artefacts of radiographic images by X-ray refraction N2 - The relevance of nano sized structures and interfaces in upcoming technologies requires new non-destructive Xray techniques exploiting attenuation as well as scattering. In the course of driving the resolution and the contrast of modern radiography into micro and nano metre dimension the inevitable scattering effects require increased attention. Several radiologists interpret the observed edge artefacts simply by 'phase contrast' due to different X-ray path lengths within the sample and others refer to Fresnel scattering. The ultra small angle scattering is of high intensity and may reach the level of the primary beam. We present monochromatic synchrotron measurements on rather simply shaped objects (such as plates and cylinders) which prove clearly the dominance of refraction intensity over total reflection and coherent small angle scattering. The refraction conditions hold for angles of incidence of several degrees to the surface, but typical deflection angles range from several seconds to minutes of arc. Additionally to the concept of 'phase contrast' of the primary beam its deflection becomes the essential issue. The appropriate removal of the attenuation contribution enables the imaging of inner surfaces and interfaces by refraction scanning topography. The presented measurements of reference particles demonstrate the reliability of laboratory refraction scanners applying X-ray tubes. T2 - 18th WCNDT - World conference on nondestructive testing CY - Durban, South Africa DA - 2012-04-16 KW - X-ray refraction KW - Small angle scattering KW - Phase contrast radiography KW - Refraction topography KW - Nanostructures KW - Nanocracks PY - 2012 UR - http://www.ndt.net/article/wcndt2012/papers/274_wcndtfinal00274.pdf SN - 978-0-620-52872-6 SP - 1 EP - 11(?) AN - OPUS4-25836 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Lück, S. A1 - Schmidt, V. A1 - Hilger, A. A1 - Garcia-Moreno, F. A1 - Manke, I. T1 - Reconstruction of limited view tomography data by DIRECTT N2 - Incomplete tomographic data sets such as limited view (missing wedge) data represent a well-known challenge for reconstruction algorithms, since they unavoidably lead to substantial image artefacts. Such data sets may occur in industrial computed tomography of limited access (e.g. extended components, fixed objects), directional opacity, limited sample life time or laminographic set-up. We present strategies to effectively suppress the typical elongation artefacts (e.g. lemon-like deformed pores) by our iterative algorithm DIRECTT which offers the opportunity to vary the versatile reconstruction parameters within each cycle. Those strategies are applied to experimental data obtained from metallic foams as well as model simulations. Comparison is drawn to state-ofthe- art techniques (filtered backprojection and algebraic techniques). Further reference is made to reconstructions of complete data sets serving as gold standards. For quantitative assessment of the reconstruction quality adapted techniques based on spatial statistics are introduced. T2 - 18th WCNDT - World conference on nondestructive testing CY - Durban, South Africa DA - 2012-04-16 KW - Computed tomography KW - Limited tomographic data KW - Iterative reconstruction KW - DIRECTT KW - Limited view KW - Missing wedge KW - Spatial statistics PY - 2012 UR - http://www.ndt.net/article/wcndt2012/papers/208_wcndtfinal00208.pdf SN - 978-0-620-52872-6 SP - 1 EP - 9(?) AN - OPUS4-25834 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Manke, I. A1 - Kardjilov, N. A1 - Arlt, Tobias A1 - Grothausmann, R. T1 - Rekonstruktion limitierter CT-Messdatensätze von Brennstoffzellen mit Directt N2 - Die Aufklärung spezifischer Fragestellungen zur Funktionalität von PEM(polymer electrolyte membrane)- und DMFC(Direct Methanol)-Brennstoffzellen bedarf der 3D-Abbildung der spezifischen Komponenten mit unterschiedlichen Strahlungsarten: des Wassergehalts in den Flow Fields mit Neutronen, der Katalysator-Alterung in der MEA (membrane electrode assembly) mit Synchrotronstrahlung und der freien (reaktiven) Katalysator-Oberfläche von Nano-Partikeln mit TEM-Elektronen-Tomografie. Diese Messungen im Bereich der mm- bis nm-Skala unterliegen dabei erheblichen Restriktionen: einer ortsabhängigen Verschmierung der Neutronenradiogramme, Manipulatorinstabilitäten der Synchrotronmessungen sowie einer Kombination von Limited-View-Datensätzen, wenigen Projektionswinkeln und teilweiser Nichtdurchstrahlbarkeit in der Elektronen-CT. Die Vorteile eines fortentwickelten Directt-Algorithmus für die Bewältigung dieser Randbedingungen gegenüber gefilterten Rückprojektionen werden aufgezeigt. KW - Computed tomography KW - Reconstruction algorithm KW - Electron tomography KW - Neutron tomography KW - Catalyst KW - Fuel cell PY - 2010 SN - 0025-5300 VL - 52 IS - 10 SP - 676 EP - 683 PB - Hanser CY - München AN - OPUS4-22070 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Kupsch, Andreas A1 - Müller, Bernd R. T1 - Numerical correction of X-ray detector backlighting N2 - A novel approach to strongly suppress artifacts in radiography and computed tomography caused by the effect of diffuse background signals ('backlighting') of 2D X-ray detectors is suggested. Depending on the detector geometry the mechanism may be different, either based on the optical scattering by the fluorescent screen materials into optical detection devices or Compton or X-ray fluorescence scattering by the detector components. Consequently, these erroneous intensity portions result in locally different violations of Lambert–Beer's law in single projections (radiographs). When used as input data for computed tomography these violations are directly observed via modulation of the projected mass as a function of the rotation phase and the sample’s aspect ratio (dynamics). The magnitude of the diffuse background signal depends on the detector area covered by the projected sample. They are more pronounced the smaller the shadowed area and the stronger the total attenuation. This implies that the reconstruction suffers from additional anisotropic artifacts caused by elongated sample structures. This issue is studied simply by absorption of flat plates in a conventional laboratory radiography set-up and at a synchrotron radiation facility. In the latter case beam hardening artifacts can be excluded due to the monochromatic radiation. The proposed correction procedure requires simple integral intensity offsets as a constant (non-local) light scattering mechanism is assumed. KW - Detector backlighting KW - X-ray detector scattering KW - Fluorescent screen KW - Diffuse background KW - Computed tomography PY - 2012 DO - https://doi.org/10.3139/146.110659 SN - 1862-5282 VL - 103 IS - 2 SP - 174 EP - 178 PB - Carl Hanser CY - München AN - OPUS4-25553 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Ewert, Uwe A1 - Osterloh, Kurt A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Beckmann, Jörg A1 - Hentschel, Manfred P. ED - Beyerer, J. T1 - Advanced radiological technologies for imaging and characterisation of threats T2 - 2nd Security Research Conference "Future Security" CY - Karlsruhe, Germany DA - 2007-09-12 KW - Threat Detection KW - Dual Energy KW - Multiple View Inspection KW - Terahertz Imaging KW - Explosives PY - 2007 SN - 978-3-86644-147-7 SP - 116 EP - 119 PB - Universitätsverl. CY - Karlsruhe AN - OPUS4-18348 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Bernd R. A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Kupsch, Andreas T1 - A comfortable procedure for correcting X-ray detector backlight N2 - A novel approach is suggested to strongly suppress artifacts in radiography and computed tomography caused by the effect of diffuse background signals 'backlighting' of 2D X-ray detectors. Depending on the detector geometry the mechanism may be different. Either based on the optical scattering of the fluorescent screen materials into the optical detection devices or Compton or X-ray fluorescence scattering by the detector components. Consequently, these erroneous intensity portions result in locally different violations of Lambert Beer's law in single projections (radiographs) as a function of the detector area coverage and the magnitude of the attenuation. The absorption of multiple metal sheets is investigated by monochromatic synchrotron radiation, thus excluding beam hardening. The proposed correction procedure simply requires the individual subtraction of one and the same fraction of the primary and transmitted mean intensity, as a constant (non-local) scattering mechanism is assumed. KW - X-ray detector backlighting KW - Radiography KW - Fluorescent screen KW - Diffuse background KW - Computed tomography PY - 2013 DO - https://doi.org/10.1088/1742-6596/425/19/192015 SN - 1742-6588 SN - 1742-6596 VL - 425 IS - 19 SP - 192015-1 EP - 192015-4 PB - IOP Publ. CY - Bristol, UK AN - OPUS4-28262 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hentschel, Manfred P. A1 - Müller, Bernd R. A1 - Lange, Axel A1 - Wald, Oliver T1 - Quantitative X-ray Determination of CFRP Micro Structures T2 - International Symposium on NDT in Aerospace CY - Fürth, Germany DA - 2008-12-03 KW - Neutronen-Radiographie KW - Neutronen-Tomographie KW - Tomographische Rekonstruktionsalgorithmen KW - Brennstoffzellen KW - In-Situ Radiologie PY - 2008 SN - 978-3-940283-12-2 N1 - Serientitel: Berichtsband / Deutsche Gesellschaft für zerstörungsfreie Prüfung e. V. – Series title: Berichtsband / Deutsche Gesellschaft für zerstörungsfreie Prüfung e. V. IS - DGZfP-BB 114 (X-Ray/Lecture 13) SP - 89 EP - 98 PB - DGZfP CY - Berlin AN - OPUS4-18606 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Görner, Wolf A1 - Hentschel, Manfred P. A1 - Müller, Bernd R. A1 - Riesemeier, Heinrich A1 - Krumrey, M. A1 - Ulm, G. T1 - The first hard X-rays at the BAMline PY - 2001 UR - http://www.helmholtz-berlin.de/media/media/oea/web/pr_webseite/druckschriften/berichte/bessy/annualreport2000.pdf#page=329 SN - 0179-4159 SP - 329 EP - 331 PB - Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung CY - Berlin AN - OPUS4-1299 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hentschel, Manfred P. A1 - Lange, Axel A1 - Müller, Bernd R. A1 - Schors, Jörg A1 - Harbich, Karl-Wolfram T1 - Röntgen-Refraktions-Computer-Tomographie N2 - Für die Charakterisierung Neuer Werkstoffe, vornehmlich Nichtmetalle, hat sich das Verfahren der Röntgen-Refraktions-Topographie bewährt. Es handelt sich phänomenologisch um eine Technik der Röntgen-Kleinwinkel-Streuung mit Probekörper-Abtastung bei fest vorgewähltem Streuwinkel. Gegenüber der klassischen Beugungstheorie dominieren jedoch bei der Streuung an Strukturen oberhalb von 0.3 µm Größe röntgenoptische Brechungseffekte. Detektierbar sind damit innere Ober- und Grenzflächen, insbesondere Mikrorisse unterhalb der lichtmikroskopischen Erkennbarkeit. Da es sich hierbei um eine Durchstrahlungs-Technik handelt, überlagern jedoch die Strukturen zu einer Projektion, analog zu den radiographischen Verfahren. Um auch Informationen entlang der Durchstrahlungs-Richtung in der Tiefe des Probekörpers zu erhalten, wird unter kleinen Streuwinkeln die Computer-Tomographie durchgeführt, im ersten Ansatz mit nur zwei Meßkanälen, jeweils für die Messung der Absorptions- und der Refraktions-Intensität. Dazu werden nacheinander 360 Linear-Scans nach Drehung von jeweils 1° aufgenommen. Die Intensitätswerte werden nach den Regeln der fouriergefilterten Rückprojektion zu Computer-Tomogrammen verarbeitet. Die Ergebnisse visualisieren die Anordnung von Grenzflächen und innere Oberflächen, die sich für zahlreiche nichtmetallische Werkstoffe, vor alllem im Transportmittel-Leichtbau als relevante Mikrostrukturen für das Versagens-Verhalten und die Werkstoff-Optimierung eignen. Zum Vergleich entstehen aus den simultanen Absorptionsmessungen gleichzeitig die klassischen Computer-Tomogramme, die ausschließlich Dichteänderungen anzeigen. T2 - Jahrestagung Zerstörungsfreie Materialprüfung 1999 CY - Celle, Deutschland DA - 1999-05-10 KW - Röntgentomographie KW - Röntgen-Refraktions-Computer-Tomographie PY - 1999 UR - http://www.ndt.net/abstract/dgzfp99/data/40.htm SN - 3-931381-27-7 VL - 1 IS - 68 SP - 361 EP - 369 PB - DGZfP CY - Berlin AN - OPUS4-715 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Bernd R. A1 - Lange, Axel A1 - Harwardt, Marco A1 - Hentschel, Manfred P. A1 - Illerhaus, Bernhard A1 - Goebbels, Jürgen T1 - Synchrotron Refraction CT and Synchrotron Bragg Magnification CT for NDE T2 - International Symposium on Digital industrial Radiology and Computed Tomography (DIR 2007) CY - Lyon, France DA - 2007-06-25 KW - X-ray Refraction KW - Diffraction Enhanced Imaging (DEI) KW - Bragg Magnification KW - Synchrotron Radiation KW - Computed Tomography (CT) KW - Metal Matrix Composites (MMC) KW - Lightweight Materials KW - Aerospace PY - 2007 IS - CD-ROM SP - 1 EP - 8 CY - Lyon, France AN - OPUS4-16366 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hentschel, Manfred P. A1 - Müller, Bernd R. A1 - Harwardt, Michael A1 - Lange, Axel T1 - Synchrotron-Refraktions-Computer Tomographie für die Materialforschung T2 - DGZfP Jahrestagung CY - Rostock, Deutschland DA - 2005-05-02 KW - Computer-Tomographie KW - Synchrotronstrahlung KW - Refraktionskontrast KW - Bragg-Vergrößerung PY - 2005 SN - 3-931381-64-1 N1 - Serientitel: Berichtsband / Deutsche Gesellschaft für zerstörungsfreie Prüfung e. V. – Series title: Berichtsband / Deutsche Gesellschaft für zerstörungsfreie Prüfung e. V. IS - 94-CD SP - 1(?) EP - 7(?) PB - DGZfP CY - Berlin AN - OPUS4-11698 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Müller, Bernd R. A1 - Hentschel, Manfred P. ED - Czichos, Horst T1 - Micro-diagnostics: X-ray and synchrotron techniques N2 - Beyond classical X-ray techniques are used for the purpose of preferably short-term applications, but some supplementary X-ray and synchrotron techniques for higher resolution microdiagnostics take advantage of scattering effects. In contrast to directly imaging methods their resolution is only limited by the diffraction limit of the X-ray wavelength, far below the atomic dimensions. These techniques of scanning topography and refraction synchrotron tomography may permit the systematic diagnostics for finding and exploiting structure/property relations like correlations among atomic, nano and microstructures with macroscopic properties. Their basic advantage over microscopic techniques is their potential for the non-destructive characterisation of materials, far from invasive sample treatments. They combine scattering and spatial resolution. KW - X-ray KW - X-ray refraction KW - X-ray refraction topography KW - X-ray refraction tomography KW - X-ray scattering KW - USAXS KW - Wide angle X-ray scattering KW - WAXS KW - Interfaces KW - Inner surface density KW - Diffraction enhanced imaging KW - DEI KW - Synchrotron radiation KW - Synchrotron refraction computed tomography KW - SRCT KW - Fibre orientation KW - X-ray diffraction microscopy PY - 2013 SN - 978-3-642-25849-7 SN - 978-3-642-25850-3 DO - https://doi.org/10.1007/978-3-642-25850-3_14 IS - Chapter 14 SP - 287 EP - 300 PB - Springer CY - Berlin Heidelberg AN - OPUS4-27746 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Fensch-Kleemann, Elisabeth A1 - Müller, Bernd R. A1 - Harbich, Karl-Wolfram A1 - Hentschel, Manfred P. ED - Kriegesmann, J. T1 - Gefügeanalyse keramischer Werkstoffe mittels Röntgen-Refraktion PY - 2002 SN - 3-87156-091-X IS - Kap. 6.1.4.1 SP - 1 EP - 24 PB - Deutscher Wirtschaftsdienst CY - Köln AN - OPUS4-2066 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. T1 - Computertomographische 2D-Rekonstruktionen ohne gefilterte Rückprojektion mit DIRECTT T2 - DACH-Jahrestagung 2008 CY - St. Gallen, Schweiz DA - 2008-04-28 KW - Computer-Tomographie KW - Rekonstruktionsalgorithmen KW - Ortsauflösung PY - 2008 SN - 978-3-940283-09-2 IS - DGZfP-BB 113 (Poster 10) SP - 1 EP - 6 AN - OPUS4-17937 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ewers, Benjamin A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. T1 - Terahertz spectral imaging techniques in NDT: Topography and computed tomography N2 - The emerging technology of generation and detection of Terahertz waves (1 THz = 1012 Hz) offers diverse potentials in non-destructive testing (NDT) regarding security as well as safety aspects. Herein, we focus on the latter with emphasis on imaging techniques. The THz range (0.1 … 10 THz, 3mm …30 µm) closes the technological gap between ultra high frequency electronics and FIR optics in the electro-magnetic (EM) spectrum. Electro-optical sampling provides straight access to the EM wave including its phase (rather than intensity). THz waves are well suited to characterize non-metallic materials since they penetrate paper, plastics, ceramics and certain composites (e.g. GFC). We employ a commercial fibre-coupled THz time domain spectrometer (TDS) for scanning the samples laterally through a focal spot. At each position the entire temporal pulse train is recorded, which offers the opportunity to use various parameters derivable for imaging. Topographic measurements are performed as reflection set-up. The achievable spatial resolution is diffraction limited at about 100 µm -300 µm (which allows for perception of single defects on a sub-mm scale). In contrast to typical pulse echoed ultrasound testing THz topography is a non-contact inspection tool without coupling agents. Several reflections of subsequent concealed layers are detected instead of just the first encountered one. Comparing to X-ray (radiology) the non-ionizing THz-waves generate images of similar contrast regarding metal and plastic (organic) components, while conventional radiography emphasizes one type of material depending on the energy preselected. Moreover, the full temporal information is exploited to derive spectra in certain selected time windows, i.e. separated spectral properties of each layer in multilayered structures. Tomographic measurements are performed in transmission mode. The sample is mounted on a rotation stage in order to allow for lateral scanning under the different projection angles. The reconstruction is typically performed by filtered backprojection, which is widely used for X-ray CT. The adaption of this technique to the THz range comes along with several experimental drawbacks such as considerable refraction and scattering. According to these difficulties we investigate the occurring artefacts. The THz-TDS provides the opportunity to calculate a separate backprojection of each frequency interval as obtained by the Fourier transformation of the recorded time resolved amplitude. This results in a spectrally resolved reconstruction of each voxel, which is unique in computed tomography technology. T2 - 10th European conference on non-destructive testing CY - Moscow, Russia DA - 2010-06-07 KW - Terahertz time domain spectroscopy KW - Spectral computed tomography KW - 3D topography PY - 2010 UR - http://www.ndt.net/article/ecndt2010/reports/1_09_10.pdf IS - Paper 4.02.18 SP - 1 EP - 10(?) AN - OPUS4-21465 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hentschel, Manfred P. A1 - Harbich, Karl-Wolfram A1 - Müller, Bernd R. A1 - Lange, Axel A1 - Schors, Jörg A1 - Wald, Oliver ED - Gerhard Busse, ED - Danny Van Hemelrijck, ED - Igor Solodov, ED - Anastasopoulos, Athanasios T1 - NDE of micro structured materials by X-ray diffraction and refraction topography T2 - 4th International Conference of Emerging Technologies in Non-Destructive Testing (ETNDT 4) CY - Stuttgart, Germany DA - 2007-04-02 KW - Nondestructive testing KW - X-ray scattering KW - X-ray topography KW - Computed topography KW - Synchrotron refraction computed tomography KW - Structure property relations KW - Composite damaging KW - Ceramics KW - Foams PY - 2007 SN - 978-0-415-46476-5 SP - 15 EP - 22 PB - Taylor & Francis CY - London, UK AN - OPUS4-17561 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Kupsch, Andreas A1 - Müller, Bernd R. T1 - Correction of diffuse X-ray detector based background N2 - A novel approach to strongly suppress artifacts in radiography and computed tomography caused by the effect of diffuse background Signals (“backlight”) of 2D X-ray detectors is suggested. Depending on the detector geometry the mechanism may be different, either based on the optical scattering of the fluorescent screen materials into optical detection devices or Compton or X-ray fluorescence scattering by the detector components. Consequently, these erroneous intensity portions result in locally different violations of Lambert Beer’s law in single projections (radiographs). When used as input data for computed tomography these violations are directly observed via modulation of the projected mass as a function of the rotation Phase and the sample’s aspect ratio (dynamics). The magnitude of the diffuse Background signal depends on the detector area covered by the projected sample. They are more pronounced the smaller the shaded area and the stronger the total attenuation. Moreover, the local intensity mismatch depends on the attenuation of the sample. We present very basic reference data measured with multiple metal foils at a synchrotron radiation source. Beam hardening artifacts can be excluded due to the monochromatic radiation. The proposed correction procedure assumes a constant (non-local) scattering mechanism. T2 - DIR 2011 - International symposium on digital industrial raidology and computed tomography CY - Berlin, Germany DA - 20.06.2011 KW - Backlight KW - X-ray detector KW - Fluorescence screen KW - Synchrotron radiography KW - Computed tomography PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-243589 SN - 978-3-940283-34-4 IS - DGZfP-BB 128 (Poster 24) SP - 1 EP - 7 PB - Deutsche Gesellscahft für Zerstörungsfreie Prüfung e.V. (DGZfP) AN - OPUS4-24358 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Kupsch, Andreas T1 - Bewertung von CT-Rekonstruktionen mit DIRECTT N2 - Modellrechnungen mit dem CT-Algorithmus DIRECTT (Direkte iterative Rekonstruktion computertomographischer Trajektorien) haben die Vorteile gegenüber anderen Ansätzen bezüglich Ortsauflösung und Dichte gezeigt, insbesondere auch für unvollständige Datensätze wie Limited View- und Region of Interest-Szenarien. Entsprechend dem Normalfall werden hier jedoch vollständige Datensätze von Modellen und Messungen und ihre Rekonstruktionen bewertet. Die Qualität von DIRECTT wird mit der Gefilterten Rückprojektion anhand der Modulations-Transfer-Funktion (MTF) sowie integraler Kenngrößen im Radon- und im Ortsraum verglichen. Zur Überprüfung der Rekonstruktionsgenauigkeit experimenteller Daten werden Mustermessungen einfacher Probengeometrien unter definierten physikalischen Bedingungen durchgeführt. Diese betreffen Monochromasie, Unterdrückung von Kantenartefakten und radiometrische Intensitätsbestimmung mit Einkanaldetektor. T2 - DGZfP-Jahrestagung 2013 CY - Dresden, Germany DA - 06.05.2013 KW - Computertomographie KW - DIRECTT KW - Modulations-Transfer-Funktion KW - CT-Algorithmus PY - 2013 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-286933 SN - 978-3-940283-49-8 IS - Poster 13 SP - 1 EP - 10 PB - Deutsche Gesellschaft für zerstörungsfreie Prüfung e.V. (DGZfP) AN - OPUS4-28693 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Manke, I. A1 - Kardjilov, N. A1 - Schäfer, R. A1 - Hilger, A. A1 - Grothausmann, R. A1 - Strobl, M. A1 - Dawson, M. A1 - Grünzweig, C. A1 - Tötzke, C. A1 - David, C. A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Banhart, J. T1 - Three-dimensional imaging of magnetic domains with neutron grating interferometry N2 - This paper gives a brief overview on3D imaging of magnetic domains with shearing grating neutron tomography. We investigated the three-dimensional distribution of magnetic domain walls in the bulk of a wedge-shaped FeSi single crystal. The width of the magnetic domains wasanalyzed at different locations within the crystal. Magnetic domains close to the tip of the wedge are much smaller than in the bulk. Furthermore, the three-dimensional shape of individual domains wasinvestigated. We discuss prospects and limitations of the applied measurement technique. KW - Neutron imaging KW - Tomography KW - Magnetic domains KW - Grating interferometry KW - Darkfield imaging KW - Shearing gratings KW - Talbot-Lau KW - Three-dimensional data quantification KW - Tomographic reconstruction PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-341919 DO - https://doi.org/10.1016/j.phpro.2015.07.057 SN - 1875-3892 VL - 69 SP - 404 EP - 412 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-34191 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -