TY - CONF A1 - Osterloh, Kurt A1 - Fratzscher, Daniel A1 - Zscherpel, Uwe A1 - Ewert, Uwe A1 - Hasenstab, A. A1 - Bücherl, T. A1 - Schillinger, B. T1 - Partielle Tomographie mit Neutronen zur Beurteilung von Leimschichten in Holz N2 - Verleimte Holzproben wurden je nach Größe mit thermischen (ANTARES) bzw. schnellen Neutronen (NECTAR) an der Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) der Technischen Universität München in Garching untersucht. Entweder ließen die durchstrahlbare Schichtdicke oder die eingeschränkte Strahlgeometrie es nicht zu, das Probenteil allseitig zu durchstrahlen. Um dennoch innere Strukturen wie Leimschichten zumindest mit einem eingeschränkten Winkelbereich tomographisch darzustellen, wurde mit Hilfe des Slice-Theorems erfolgreich rekonstruiert. Ein Brett von 2 cm Dicke wurde mit thermischen Neutronen erfolgreich untersucht, ein größeres mit schnellen. T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Germany DA - 30.05.2011 KW - Neutronentomographie KW - Eingeschränkter Winkelbereich KW - Holz PY - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-250649 SN - 978-3-940283-33-7 VL - 127 SP - 1 EP - 6 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-25064 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Osterloh, Kurt A1 - Fratzscher, Daniel A1 - Jechow, Mirko A1 - Bücherl, T. A1 - Schillinger, B. A1 - Hasenstab, A. A1 - Zscherpel, Uwe A1 - Ewert, Uwe T1 - Limited view tomography of wood with fast and thermal neutrons N2 - Neutrons are absorbed particularly by hydrogen containing materials so they can be used as a tool for visualising heterogeneous density distributions of organic materials. Penetration limits are set by the layer thicknesses and the neutron energies applied. In case of specimens with a flat shape the situation may be encountered that the object only could be penetrated in selected directions. In addition, the overall size may exceed the beam diameter and thus the viewing window if a certain region of interest should be studied by tomography without destroying the integrity of the specimen. This study shows the capabilities and limits of thermal and fast neutrons to investigate flat wooden specimens such as boards and girders by neutron tomography under such circumstances. Taking projections was impaired either by the limits of penetrability or by the total size of the object. As a consequence, projections were included for reconstruction only from a limited angular range of 90°. It could be shown that an approach based on the slice theorem was capable to visualise structural features along the beam directions while simply omitting the perpendicular ones without causing additional artefacts. Small samples with a thickness of up to 2 cm but several times broader could be studied with the ANTARES facility of the FRM II neutron source in Garching providing thermal neutrons while larger objects required a beam of higher energy as available in the NECTAR facility of the same institution. The fast (fission) neutrons (1.5 – 2 MeV) of this site allowed investigating an area of interest inside a girder with a cross section of 23.5 x 49 cm². Internal features such as inclusions could be detected as well as a heterogeneous density distribution in glue layers. T2 - International symposium on digital industrial radiology and computed tomography CY - Berlin, Germany DA - 20.06.2011 KW - Computed tomography KW - Slice theoreme KW - Limited angle tomography PY - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-250663 SN - 978-3-940283-34-4 VL - 128 SP - 1 EP - 5 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-25066 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Osterloh, Kurt A1 - Bücherl, T. A1 - Lierse von Gostomski, C. A1 - Zscherpel, Uwe A1 - Ewert, Uwe A1 - Bock, S. T1 - Filtering algorithm for dotted interferences N2 - An algorithm has been developed to remove reliably dotted interferences impairing the perceptibility of objects within a radiographic image. This particularly is a major challenge encountered with neutron radiographs collected at the NECTAR facility, Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II): the resulting images are dominated by features resembling a snow flurry. These artefacts are caused by scattered neutrons, gamma radiation, cosmic radiation, etc. all hitting the detector CCD directly in spite of a sophisticated shielding. This makes such images rather useless for further direct evaluations. One approach to resolve this problem of these random effects would be to collect a vast number of single images, to combine them appropriately and to process them with common image filtering procedures. However, it has been shown that, e.g. median filtering, depending on the kernel size in the plane and/or the number of single shots to be combined, is either insufficient or tends to blur sharp lined structures. This inevitably makes a visually controlled processing image by image unavoidable. Particularly in tomographic studies, it would be by far too tedious to treat each single projection by this way. Alternatively, it would be not only more comfortable but also in many cases the only reasonable approach to filter a stack of images in a batch procedure to get rid of the disturbing interferences. The algorithm presented here meets all these requirements. It reliably frees the images from the snowy pattern described above without the loss of fine structures and without a general blurring of the image. It consists of an iterative, within a batch procedure parameter free filtering algorithm aiming to eliminate the often complex interfering artefacts while leaving the original information untouched as far as possible. KW - Neutron KW - Radiography KW - Tomography KW - Filtering KW - Evaluation KW - NECTAR PY - 2011 U6 - https://doi.org/10.1016/j.nima.2011.01.107 SN - 0168-9002 SN - 0167-5087 VL - 651 IS - 1 SP - 171 EP - 174 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-24917 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Osterloh, Kurt A1 - Bücherl, T. A1 - Zscherpel, Uwe A1 - Ewert, Uwe T1 - Image recovery by removing stochastic artefacts identified as local asymmetries N2 - Stochastic artefacts are frequently encountered in digital radiography and tomography with neutrons. Most obviously, they are caused by ubiquitous scattered radiation hitting the CCD-sensor. They appear as scattered dots and, at higher frequency of occurrence, they may obscure the image. Some of these dotted interferences vary with time, however, a large portion of them remains persistent so the problem cannot be resolved by collecting stacks of images and to merge them to a median image. The situation becomes even worse in computed tomography (CT) where each artefact causes a circular pattern in the reconstructed plane. Therefore, these stochastic artefacts have to be removed completely and automatically while leaving the original image content untouched. A simplified image acquisition and artefact removal tool was developed at BAM and is available to interested users. Furthermore, an algorithm complying with all the requirements mentioned above was developed that reliably removes artefacts that could even exceed the size of a single pixel without affecting other parts of the image. It consists of an iterative two-step algorithm adjusting pixel values within a 3 × 3 matrix inside of a 5 × 5 kernel and the centre pixel only within a 3 × 3 kernel, resp. It has been applied to thousands of images obtained from the NECTAR facility at the FRM II in Garching, Germany, without any need of a visual control. In essence, the procedure consists of identifying and tackling asymmetric intensity distributions locally with recording each treatment of a pixel. Searching for the local asymmetry with subsequent correction rather than replacing individually identified pixels constitutes the basic idea of the algorithm. The efficiency of the proposed algorithm is demonstrated with a severely spoiled example of neutron radiography and tomography as compared with median filtering, the most convenient alternative approach by visual check, histogram and power spectra analysis. KW - Data processing methods KW - Image filtering KW - Pattern recognition KW - Cluster finding KW - Calibration and fitting methods PY - 2012 U6 - https://doi.org/10.1088/1748-0221/7/04/C04018 SN - 1748-0221 VL - 7 IS - April SP - 1 EP - 14 PB - Inst. of Physics Publ. CY - London AN - OPUS4-25877 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Osterloh, Kurt A1 - Zscherpel, Uwe A1 - Rädel, Christoph A1 - Weidemann, Gerd A1 - Meinel, Dietmar A1 - Goebbels, Jürgen A1 - Ewert, Uwe A1 - Hasenstab, A. A1 - Bücherl, T. T1 - Durchstrahlungsprüfung von Holz T2 - DGZfP-Jahrestagung 2007 CY - Fürth, Deutschland DA - 2007-05-14 KW - Digitale Radiographie KW - Tomographie KW - Spaltneutronen KW - Neutronenradiographie PY - 2007 SN - 978-3-931381-98-1 IS - DGZfP-BB 104 (Vortrag 40) SP - 1 EP - 12 AN - OPUS4-20717 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Osterloh, Kurt A1 - Ewert, Uwe A1 - Rädel, Christoph A1 - Zscherpel, Uwe A1 - Hasenstab, A. A1 - Bücherl, T. T1 - Radiographie und Tomographie von Holz mit Neutronen T2 - DGZfP-Jahrestagung 2008 CY - St. Gallen, Switzerland DA - 2008-04-28 KW - Materialgeschichtliches KW - Möglichkeiten der Neutronenradiographie PY - 2008 SN - 978-3-940283-09-2 IS - DGZfP-BB 113 (Poster 30) SP - 727 EP - 733 AN - OPUS4-20714 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Osterloh, Kurt A1 - Jechow, Mirko A1 - Fratzscher, Daniel A1 - Wrobel, Norma A1 - Zscherpel, Uwe A1 - Ewert, Uwe A1 - Bücherl, T. A1 - Hasenstab, A. A1 - Weiss, P. A1 - Weiss, C. A1 - Tannert, T. T1 - Strukturmerkmale im Holz - radiologisch gesehen N2 - Die radiologische Untersuchung von Holz ist hinsichtlich der Durchführung und Auswertung komplex. Im Gegensatz zu künstlich hergestellten Materialien zeichnet sich Holz besonders durch seine Heterogenität und Individualität aus, kein Stück ist wie das andere. Dies erschwert bei der radiologischen Inspektion die Fehlerdetektion, da diese teilweise schwer von natürlichen Wachstumsmerkmalen zu unterscheiden sind. Insektenfraßgänge und Hohlräume durch biologischen Abbau sind deutlich erkennbar, schwieriger wird es bei feinen Rissen und Anzeichen für Fäulnis. Metallische Einbauten wie Nägel und Bolzen sind natürlich gut zu erkennen, großflächigere Platten können jedoch den Einblick in die benachbarten Gebiete versperren. Klebstoffschichten sind im Röntgenbild nur dann sichtbar, wenn sie exakt parallel zum Strahlengang getroffen werden. Verschiedene Strukturmerkmale treten also radiologisch recht unterschiedlich in Erscheinung, deshalb liegt es nahe, zu deren Erkennung mehr als nur eine Durchstrahlungstechnologie anzuwenden. Während bei immobilen Objekten, d.h. Bauwerken und Bäumen, mobile Durchstrahlungstechniken mit Röntgen- oder Gammastrahlen (Se-75) in Frage kommen, stehen im Labor auch (schnelle) Neutronen alternativ zur Verfügung. Die verschiedenen Techniken, einschließlich der Tomographie mit Neutronen, werden an zwei größeren Prüfteilen demonstriert, einer Brettschichtholzprobe und einem Knotenpunkt aus einer Holzbrücke mit eingebauter Stahlplatte. Neutronen lassen Materialunterschiede differenzierter hervortreten und durchdringen sperrige Metallteile besser, trotz verringerter Bildqualität. An Verbesserungen wird derzeit gearbeitet. T2 - DGZfP-Jahrestagung 2010 CY - Erfurt, Deutschland DA - 2010-05-10 KW - Mobile Radiographie KW - Holzbauteilprüfung PY - 2010 SN - 978-3-940283-26-9 IS - DGZfP-BB 122 (Poster 14) SP - 1 EP - 2 CY - Berlin AN - OPUS4-22532 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Osterloh, Kurt A1 - Jechow, Mirko A1 - Fratzscher, Daniel A1 - Wrobel, Norma A1 - Zscherpel, Uwe A1 - Ewert, Uwe A1 - Bücherl, T. A1 - Schillinger, B. A1 - Schwabe, A. A1 - Hasenstab, A. A1 - Weiss, P. A1 - Weiss, C. A1 - Tannert, T. T1 - Durchstrahlungsverfahren - Ein komplexer Einblick in Objekte, ohne sie zu zerlegen T2 - Jahrestagung Archäometrie und Denkmalpflege 2010 CY - Bochum, Deutschland DA - 2010-09-15 KW - Mobile Radiographie KW - Neutronentomographie KW - Archäologischer Nassholzfund PY - 2010 SN - 0947-6229 IS - Metalla Sonderheft SP - 52 EP - 54 CY - Bochum AN - OPUS4-22539 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Osterloh, Kurt A1 - Bellon, Carsten A1 - Hohendorf, Stefan A1 - Kolkoori, Sanjeevareddy A1 - Wrobel, Norma A1 - Nusser, A. A1 - Freitag, M. A1 - Bücherl, T. A1 - Bar, D. A1 - Mor, I. A1 - Tamin, N. A1 - Weiss-Babai, R. A1 - Bromberger, B. A1 - Dangendorf, V. A1 - Tittelmeier, K. T1 - Computed tomography with X-rays and fast neutrons for restoration of wooden artwork N2 - The objects of this investigation were sculptures taken from a ca. three hundred years old baroque epitaph of a church in Tonning, a town in Northern Germany. Around 1900 it was found in a disastrous state heavily damaged by wood-worm. At that time, the whole artwork was treated with the tar extract carbolineum as a remedy. Nowadays, this substance has been identified as carcinogenic, and its presence can be perceived by its stench and visually at certain spots on the surface where it has penetrated the covering paint. A gold-painted sculpture of a massive wooden skull was interrogated with X-rays and fast neutrons to investigate the internal distribution of the carbolineum. The X-ray tomography, with its excellent spatial resolution revealed galleries left over from the worm infestation in the outer areas and cracks in the central region. The golden color coating appeared as a thick and dense layer. In comparison the tomography with fast neutrons, though being of lower resolution and yet unresolved artefacts revealed sections of slightly different densities in the bulk of the wood. These differences we attribute to the differences in the distribution of the impregnant in the wood, visible due to its higher hydrogen content making it less transparent for neutrons. T2 - WCNR-10 - 10th World conference on neutron radiography CY - Grindelwald, Switzerland DA - 05.10.2014 KW - Computed tomography KW - Neutron radiology KW - Conservation of wooden artwork PY - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-323050 SN - 1875-3892 VL - 69 SP - 472 EP - 477 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-32305 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Osterloh, Kurt A1 - Röhrs, S. A1 - Schwabe, A. A1 - Radujcovic, S. A1 - Bücherl, T. A1 - Dangendorf, V. A1 - Zscherpel, Uwe A1 - Reiche, I. A1 - Nüsser, A. ED - Zscherpel, Uwe ED - Kasperl, S. T1 - Elucidating the distribution of organic consolidants in wood by Neutron Tomography N2 - While the absorption of X-rays and gamma radiation is determined by the Z-number of the elements a specimen is composed of, it is the hydrogen making an effective contrast with neutron imaging. As a consequence, interrogating with neutrons presents a suitable tool to study the distribution of organic consolidants in materials such as wood as encountered in impregnated wooden artworks. Four different examples of objects are presented here to demonstrate the potential of neutron CT: 1) small wooden pieces of ship wrecks (< 2 cm thickness) interrogated with cold neutrons (0.5 meV at the ANTARES facility of the FRM II in Garching) to demonstrate the potential and the limitation of using low energy neutrons, 2) a wooden statue soaked with carbolineum (fission neutrons 1.8 MeV at the NECTAR facility of the FRM II), 3) a smaller wooden figure of a skull heavily soaked with carbolineum so it was too tight for the fission neutrons used before with accelerator neutrons (broad range about 5.5 MeV at the PTB in Braunschweig) and 4) pieces of charred wood to study the impregnation with a consolidant (NECTAR, FRM II). With the exception of the last example, all results have been combined with X-ray tomography (BAM 8.3 in Berlin). In the case of the charred wood specimens (example 4) the density histograms of the neutron tomography results were compared with those obtained from untreated references. The observed gain in specific density of the soaked specimens corresponded with an increase of specific weight. All results obtained so far showed distinct distribution patterns attributable to structural peculiarities or organic consolidants providing valuable support for subsequent restoration works. T2 - International symposium on digital industrial radiography and computed tomography DIR2019 CY - Fürth, Germany DA - 02.07.2019 KW - Neutron Imaging KW - Cold to fast neutron testing KW - Tomography of wood samples KW - Art restauration PY - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-505326 UR - https://www.ndt.net/search/docs.php3?id=24740 SN - 1435-4934 VL - 24 IS - 11 SP - 1 EP - 8 PB - NDT.net CY - Kirchwald AN - OPUS4-50532 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -