TY - GEN A1 - Perk, M. A1 - Großwig, S. A1 - Pfeiffer, T. A1 - Rembe, M. A1 - den Hartogh, M. A1 - Weege, S. A1 - Krebber, Katerina A1 - Dijk, H. L. T1 - Faseroptische Leckage-Ortung zum Nachweis von Undichtheiten in Bohrlochkomplettierungen N2 - Im Rahmen der Integritätsbe­wertung einer zementierten 13 3/8" Rohrtour einer Sole-Produktionsbohrung wurden erstmals 2018 zeitgleich faserop­tische Temperaturmessungen (DTS) und faseroptische Akustikmessungen (DAS) durchgeführt und ausgewertet. Dazu wurde die Bohrung zeitweise mit Stick­stoff bespannt und wieder entlastet. T2 - DGMK/ÖGEW-Frühjahrstagung 2020 CY - Celle, Germany DA - 15.​04.​2020 KW - Kavernenspeicher KW - Verteilte faseroptische akustische Sensorik KW - Wasserstoffspeicher PY - 2020 N1 - Die DGMK/ÖGEW Frühjahrstagung 2020 wurde abgesagt, der Tagungsband aber trotzdem veröffentlicht. - The DGMK/ÖGEW Frühjahrstagung 2020 was cancelled, the proceedings were published nevertheless. VL - 136 IS - 4 SP - 25 EP - 26 PB - DVV Media Group CY - Hamburg AN - OPUS4-50783 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander A1 - Krebber, Katerina ED - Karabay, G. ED - Kara, S. T1 - Smart geosynthetics for structural health monitoring using fully distributed fiber optic sensors N2 - We report on the development of a complete system for structural health monitaring of large-scale geotechnical structures. The system uses Brillouin frequency domain analysis (BOFDA) for distributed measurement of strain and temperature along glass optical fibers (GOFs) by determining the so-called Brillouin frequency shift (BFS). ln a number of research activities we managed to optimize the BOFDA measurement setup regarding the spatial resolution and the accuracy of the measured quantities. Moreover, we realized a simultaneaus measurement of strain and temperature by using nonzero dispersion-shifted fibers (NZDSFs) with several multiple Brillouin scattering resonances. ln cooperation with our German and ltalian industry partners we finally succeeded in fabricating low-attenuation smart geosynthetics as a sensor component of a fully distributed Brillouin-based fiber optic monitaring system. T2 - 6th International Technical Textiles Congress CY - Izmir, Turkey DA - 14.10.2015 KW - Brillouin scattering KW - Distributed sensor KW - Fiberoptic sensor KW - Optical fiber KW - Structural health monitoring PY - 2015 SN - 978-975-441-448-6 SP - 215 EP - 218 PB - Meta Basim Pr. AN - OPUS4-34772 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fasano, A. A1 - Woyessa, G. A1 - Stajanca, Pavol A1 - Markos, C. A1 - Stefani, A. A1 - Nielsen, K. A1 - Rasmussen, H. K. A1 - Krebber, Katerina A1 - Bang, O. T1 - Production and characterization of polycarbonate microstructured polymer optical fiber bragg grating sensor N2 - We present the fabrication and characterization of a polycarbonate (PC) microstructured polymer optical fiber (mPOF) and the writing of a fiber Bragg grating (FBG) in it to obtain a polymer optical FBG sen-sor. The manufacturing process of the PC mPOF consists of multiple consecutive stages, such as casting of pol-ymer granulates into a solid rod, machining and drilling of a 3-ring hexagonal lattice of holes into it, and finally drawing into fiber. We demonstrate that the obtained PC mPOF is photosensitive and FBGs can be conveniently inscribed into it, thereby enabling FBG-based temperature and strain sensing. The PC optical fibers are for some applications an attractive alternative to conventional materials used in POF fabrication, such as polymethyl methacrylate (PMMA). In general, PC can be used at temperature up to 120 °C and breaks at considerably higher strains than PMMA. T2 - POF 2015 - 24th International conference on plastic optical fibers CY - Nürnberg, Germany DA - 22.09.2015 PY - 2015 SP - 64 EP - 67 AN - OPUS4-34587 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liehr, Sascha A1 - Burgmeier, J. A1 - Krebber, Katerina T1 - Quasi-distributed fiber bend and temperature measurement in femtosecond laser-structured POF N2 - We propose to use focused femtosecond laser pulses to inscribe Scattering damage in the core of polymer optical fibers for interrogation as quasi-distributed sensor points by optical time domain reflectometry. Fiber bend measurement is demonstrated on off-center inscribed sensor points and absolute temperature measurement is presented by evaluation of the constant backscatter intensities from the inscribed structures relative to temperature-dependent Rayleigh Scattering. Application possibilities and limitations of this new approach are discussed. T2 - POF 2013 - 22nd International conference on plastic optical fibers CY - Búzios, Rio de Janeiro, Brazil DA - 11.09.2013 KW - POF KW - Polymer optical fiber KW - Femtosecond laser KW - Optical fiber sensors KW - OTDR KW - Backscatter measurement PY - 2013 SP - 279 EP - 284 CY - Rio de Janeiro, Brazil AN - OPUS4-30082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Steffen, Milan A1 - Liehr, Sascha A1 - Basedau, Frank A1 - Krebber, Katerina ED - López-Higuera, J.M. ED - Jones, J. ED - López-Amo, M. ED - Santos, J.L. T1 - Simultaneous vibration and quasi-distributed strain measurement using incoherent OFDR and extrinsic Fabry-Perot interferometers N2 - We present a measurement setup for combined quasi-distributed strain and dynamic point-wise vibration measurement using an incoherent optical frequency domain reflectometry (I-OFDR) setup in combination with extrinsic Fabry-Perot interferometers (EFPIs). Several EFPIs can be multiplexed and at the same time the strain along their supply fibres can be measured in a quasi-distributed manner. The setup is characterised and a demonstration of its general performance is given. T2 - OFS2014 - 23rd International conference on optical fibre sensors CY - Santander, Spain DA - 02.06.2014 KW - Optical fibre sensor KW - EFPI KW - I-OFDR KW - Quasi-distributed KW - Strain KW - Dynamic length and power management PY - 2014 DO - https://doi.org/10.1117/12.2059616 SN - 0277-786X SN - 1996-756X N1 - Serientitel: Proceedings of SPIE – Series title: Proceedings of SPIE VL - 9157 SP - 91576S-1 EP - 91576S-4 AN - OPUS4-31039 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sporea, D. A1 - Mihai, L. A1 - Negut, Daniel A1 - Stajanca, Pavol A1 - Krebber, Katerina ED - Kalli, K. ED - Mendez, A. T1 - On-line monitoring of gamma irradiated perfluorinated polymer optical fiber N2 - In this paper, we present the first results regarding the on-line monitoring of gamma-ray exposure effects on a commercial multi-mode perfluorinated polymer optical fiber (PF-POF), type GigaPOF-50SR from Chromis Fiberoptics. Our focus was to evaluate on-line the radiation induced attenuation (RIA) over a wide spectral range (320 nm – 1700 nm), in order to assess the fiber’s radiation hardness and its possible use in radiation detection. An Ocean Optics QE65000 high sensitivity spectrometer and a StellarNet near-IR spectrometer were used to cover the spectral ranges 200 nm – 1μm and 900 nm – 1.6 μm, respectively. Electron paramagnetic resonance was used to monitor the recovery of the irradiation induced centers at room temperature. The study indicated that the optical fiber can be used as radiation monitor at low dose rates by measuring the attenuation in the UV, while higher dose rates irradiation can be observed by RIA monitoring at specific wavelengths in the visible spectral range. T2 - Photonics Europe 2016, Micro-Structured and Specialty Optical Fibers IV CY - Brussels, Belgium DA - 03.04.2016 KW - electron paramagnetic resonance spectroscopy KW - Perfluorinated polymer optical fiber KW - radiation effects KW - gamma irradiation KW - radiation hardness KW - radiation induced attenuation KW - radiation dosimetry PY - 2016 DO - https://doi.org/10.1117/12.2230688 VL - 9886 SP - 98861Q-1 EP - 98861Q-6 PB - SPIE CY - Bellingham, USA AN - OPUS4-35927 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fasano, A. A1 - Woyessa, G. A1 - Stajanca, Pavol A1 - Markos, C. A1 - Stefani, A. A1 - Nielsen, K. A1 - Rasmussen, H. K. A1 - Krebber, Katerina A1 - Bang, O. ED - Kalli, K. ED - Mendez, A. T1 - Creation of a microstructured polymer optical fiber with UV Bragg grating inscription for the detection of extensions at temperatures up to 125°C N2 - We describe the fabrication of a polycarbonate (PC) micro-structured polymer optical fiber (mPOF) and the writing of fiber Bragg gratings (FBGs) in it to enable strain and temperature measurements. We demonstrate the photosensitivity of a dopant-free PC fiber by grating inscription using a UV laser. We further show that PC Bragg gratings can be extended up to at least 3% without affecting the initial functionality of the micro-structured fiber. The response of PC FBGs to temperature up to 125°C is also investigated. Polycarbonate has good mechanical properties and its high temperatureresistance might extend the range of application of polymeric FBGs. T2 - Photonics Europe 2016, Micro-Structured and Specialty Optical Fibres IV CY - Brussels, Belgium DA - 03.04.2016 KW - fiber Bragg gratings KW - Polycarbonate KW - polymers KW - micro-structured polymer optical fibers KW - UV laser inscription KW - optical fiber sensors PY - 2016 DO - https://doi.org/10.1117/12.2227843 VL - 9886 SP - 988619-1 EP - 988619-6 PB - SPIE AN - OPUS4-35928 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rohwetter, Philipp A1 - Eisermann, René A1 - Krebber, Katerina T1 - Random quadrature demodulation for direct detection single-pulse rayleigh C-OTDR N2 - We present a demodulation method that partially compensates for the nonlinear and random transfer function of fiber-optic direct detection coherent Rayleigh optical time-domain reflectometry (C-OTDR). Specifically, the proposed method is shown to improve the detection of small amplitude, high frequency dynamic optical fiber strain as it occurs in acoustic emission sensing. The method is applicable provided that the dynamic fiber strain to be sensed is known to affect a longer section of sensing fiber in a spatially homogeneous way. It is shown that this knowledge can be used to extract more quantitative information from the measured C-OTDR signal by averaging signal components from the affected fiber section in a suitable and efficient way. The theoretical basis of the method is developed and supporting experimental results are presented. KW - Optical fiber sensors KW - Coherent optical time-domain reflectometry (C-OTDR) KW - Fiber-optic speckle interferometry KW - Remote acoustic emission sensing PY - 2016 DO - https://doi.org/10.1109/JLT.2016.2557586 SN - 0733-8724 VL - 34 IS - 19 SP - 4437 EP - 4444 PB - IEEE CY - Piscataway, NJ, USA AN - OPUS4-35948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stajanca, Pavol A1 - Mihai, L. A1 - Sporea, D. A1 - Negut, D. A1 - Krebber, Katerina ED - Lewis, E. T1 - Perfluorinated polymer optical fiber for gamma radiation monitoring N2 - The sensitivity of low-loss perfluorinated polymer optical fiber (PF-POF) to gamma radiation is investigated for on-line radiation monitoring purposes. The radiation-induced attenuation (RIA) of a commercial PF-POF based on Cytop material is measured in the visible spectral region. The fiber RIA shows strong wavelength dependence with rapid increase towards the blue side of the spectrum. The wide range of radiation sensitivities is available via careful selection of appropriate monitoring wavelength. The accessible sensitivities span from 1.6 ± 0.2 dBm-1/kGy measured at 750 nm to 18.3 ± 0.7 dBm-1/kGy measured at 420 nm. The fairly high radiation sensitivity as well as its wide tunability makes the fiber a promising candidate for a broad range of applications. T2 - Sixth European Workshop on Optical Fibre Sensors CY - Limerick, Ireland DA - 31.05.2016 KW - Perfluorinated polymer optical fiber KW - Cytop KW - gamma radiation KW - optical fiber sensors KW - radiation dosimetry PY - 2016 UR - http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2525047&resultClick=1 DO - https://doi.org/10.1117/12.2235528 VL - 9916 SP - 99160H-1 EP - 99160H-4 PB - SPIE CY - Bellingham, WA, USA AN - OPUS4-36461 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lu, Xin A1 - Krebber, Katerina T1 - Direct detection based φOTDR using the Kramers-Kronig receiver N2 - A Kramers-Kronig (KK) receiver is applied to a phase-sensitive optical time domain reflectometry based on direct detection. An imbalanced Mach-Zehnder interferometer with a 2× 2 coupler is used in sensing system to encode the phase information into optical intensity. The directly obtained signal is treated as the in-phase component, and the KK receiver provides the quadrature component by Hilbert transform of the obtained signal, so that the optical phase can be retrieved by IQ demodulation. The working principle is well explained, and the obtained phase variance is theoretically analyzed. The experiment demonstrates the functionality of the sensor and validates the theoretical analysis. KW - Kramers-Kronig detector KW - Distributed fiber sensing KW - Acoustic sensing PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-516803 UR - https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-28-24-37058&id=442839 DO - https://doi.org/10.1364/OE.405723 VL - 28 IS - 24 SP - 37058 EP - 37068 PB - Optical Society of America AN - OPUS4-51680 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Perk, M. A1 - Großwig, S. A1 - Pfeiffer, T. A1 - Rembe, M. A1 - den Hartogh, M. A1 - Weege, S. A1 - Krebber, Katerina A1 - Dijk, H. L. T1 - Faseroptische Leckage-Ortung zum Nachweis von Undichtheiten in Bohrlochkomplettierungen N2 - Im Rahmen der Integritätsbewertung einer zementierten 13 3/8" Rohrtour einer Sole-Produktionsbohrung wurden erstmals 2018 zeitgleich faseroptische Temperaturmessungen (DTS, Distributed Temperature Sensing) und faseroptische Akustikmessungen (DAS, Distributed Acoustic Sensing) durchgeführt und ausgewertet. Dazu wurde die Bohrung zeitweise mit Stickstoff bespannt und wieder entlastet. Durch die Bespannung der Bohrung mit Stickstoff in Kombination mit dem Herunterdrücken des Stickstoff-Sole-Spiegels unter den Rohrschuh der 13 3/8" Rohrtour, konnte Stickstoff aus der Kavernenbohrung durch eine Leckagestelle in die Zementation übertreten und dort ein Stickstoff-Reservoir bilden. Bei der anschließenden Stickstoffentlastung erfolgte der Wiederanstieg des Stickstoff-Sole-Spiegels deutlich schneller als die Entleerung des in der Zementation angelegten Stickstoff-Reservoirs. Der dadurch entstandene Druckgradient hatte zur Folge, dass an der Leckagestelle der Stickstoff aus der Zementation in die aufsteigende Sole in Form von Bläschen eingetreten und dort aufgestiegen ist. Dieser Übertritt der Stickstoffbläschen war sowohl mit der Entstehung eines akustischen Geräusches als auch mit einer Temperaturänderung verbunden, welche mit der DAS- und DTS-Technik nachgewiesen werden konnten. Um die Ergebnisse bzgl. ihres physikalischen Hintergrundes zu überprüfen und basierend auf einer mathematisch-physikalischen Grundlage eine nachvollziehbare Interpretation der Messergebnisse zu ermöglichen, wurde ein numerisches Simulationsmodell der gekoppelten Festkörper- und Druckakustik für die Bohrung aufgebaut. Das Modell berücksichtigt die Geologie und die Komplettierung der Kavernenbohrung. Nach Identifikation der Schallquelle konnte mit dem Modell die Ausbreitung des Schalldrucks in der Bohrung erfolgreich nachgestellt werden. Um dieses Verfahren einer simultanen DAS-DTS-Messung in eine feldtaugliche Version zu überführen, läuft seit November 2019 ein breit angelegtes und vom BMWi gefördertes ZIM-Kooperationsprojekt zwischen der Bundesanstalt für Materialforschung und -prüfung (BAM), der IAB Weimar gGmbH, der GESO GmbH & Co. Projekt KG, der DEEP.KBB GmbH sowie der Rembe Consulting PartG mbB. Durch die Messdatenkopplung und den Wegfall der bewegungsbedingten Nachteile einer Messsonde werden präzisere Ergebnisse zur Bewertung der Bohrlochintegrität erwartet. Das Ziel ist, mit Hilfe der noch zu entwickelnden einfachen und robusten Technik, quantitative Aussagen über die Zustände im verrohrten Bohrloch direkt am Messplatz treffen zu können, wobei ein Fokus auf Detektierung und Quantifizierung von Kleinstleckagen liegt. Im Rahmen dieses Forschungsprojektes kommt neben numerischen Berechnungen auch ein geplanter Bohrlochsimulator zum Einsatz, mit dem umfangreiche Untersuchungen zur Ermittlung der Grenzparameter und Detektionsschwellen durchgeführt werden sollen. T2 - DGMK/ÖGEW-Frühjahrstagung 2020 CY - Celle, Germany DA - 15.​04.​2020 KW - Kavernenspeicher KW - Verteilte faseroptische akustische Sensorik KW - Wasserstoffspeicher PY - 2020 UR - https://dgmk.egnyte.com/fl/k3KJMqKMSb#folder-link/ SN - 978-3-947716-04-3 SN - 1433-9013 N1 - Die DGMK/ÖGEW Frühjahrstagung 2020 wurde abgesagt, der Tagungsband aber trotzdem veröffentlicht. - The DGMK/ÖGEW Frühjahrstagung 2020 was cancelled, the proceedings were published nevertheless. VL - DGMK-Tagungsbericht 2020-1 SP - 106 EP - 121 PB - DGMK - Deutsche Wissenschaftliche Gesellschaft für Erdöl, Erdgas und Kohle CY - Hamburg AN - OPUS4-52159 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lu, Xin A1 - Krebber, Katerina T1 - Characterizing detection noise in phase-sensitive optical time domain reflectometry N2 - Phase-sensitive optical time domain reflectometry (φOTDR) is an excellent distributed fiber sensing technique and has been applied in various areas. Its noise is however never been comprehensively studied to the best of our knowledge. The different detection noise sources in such a sensing system are thoroughly investigated. The impacts of thermal noise, shot noise and the beat between signal and the amplified spontaneous emission from a pre-amplifier have been theoretically and experimentally demonstrated. Due to the random nature of the φOTDR signal, the detection noise demonstrates distinct features at different fiber positions in a single measurement. The theoretical analysis and the experimental result explicitly affirm most of the fiber sections, and the difference at some positions may be explained by ambient noise. KW - Noise analysis KW - Acoustic sensing KW - Distributed fiber sensing PY - 2021 DO - https://doi.org/https://doi.org/10.1364/OE.424410 SN - 1094-4087 VL - 29 IS - 12 SP - 18791 EP - 18806 PB - Optical Society of America CY - Washington, DC AN - OPUS4-52757 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander A1 - Krebber, Katerina T1 - Faseroptische Strahlungssensoren für kerntechnische Anwendungen N2 - Der Anstieg der Vielfalt nuklearer Anwendungen weit über die Bereiche der kerntechnischen Stromerzeugung erhöht die Relevanz der Entwicklung und Anwendung neuer Technologien zur Strahlungsüberwachung. Auch die offenen Sicherheitsfragen bei der Entsorgung radioaktiver Abfälle einschließlich Zwischen- und Endlagerungsproblematik verstärkt die Nachfrage nach effizienten Monitoringsystemen zum Schutz von Mensch und Umwelt vor ionisierender Strahlung. Aufgrund ihrer messtechnisch vorteilhaften Materialeigenschaften stellen die faseroptischen Strahlungssensoren eine vielversprechende Alternative zu traditionellen Dosimetern dar. Bedingt durch ihre kleinen Abmessungen, elektromagnetische Unempfindlichkeit und ihr geringes Gewicht können faseroptische Sensoren in einer harschen Umgebung an schwer zugänglichen Stellen eingesetzt werden. Darüber hinaus bietet diese Art der Sensoren die Möglichkeit der ortsverteilten Messung entlang der gesamten Sensorfaser. Somit kann durch eine einzelne optische Faser eine Vielzahl an punktuell messenden Sensoren ersetzt werden. Dieser Beitrag beschreibt die in der BAM vorangetriebenen Entwicklungen unterschiedlicher Sensorprinzipien, -lösungen und -verfahren zur Detektion ionisierender Strahlung. T2 - 2. Tage der Standortauswahl CY - Online meeting DA - 11.02.2021 KW - Faseroptischer Strahlungssensor KW - Ortsauflösende Fasersensorik KW - Strahlungsinduzierte optische Dämpfung KW - Gammastrahlung KW - Rayleigh-Streuung KW - Brillouin-Streuung PY - 2021 SP - 43 AN - OPUS4-52211 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Portella, Pedro Dolabella A1 - Krebber, Katerina T1 - Fiber Optic Sensors for SHM - From Laboratory to Industrial N2 - The paper highlights the research activities in Germany and Europe in the development of distributed fiber optic sensor for structural health monitoring (SHM) like the monitoring of geotechnical and civil infrastructures and presents selected results achieved within these projects. T2 - Conaendi & IEV 2021 CY - Online meeting DA - 09.03.2021 KW - Fiber KW - Optic KW - SHM PY - 2021 AN - OPUS4-52254 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander A1 - Krebber, Katerina T1 - Distributed fiber optic radiation sensors N2 - In this work, we present our results achieved in several research activities for development of distributed fiber optic radiation sensors using glass and polymer optical fibers. The findings show that both the measurement of the radiation-induced attenuation (RIA) along the entire sensing fiber and the accompanying change in the refractive index of the fiber core can be used for distributed radiation monitoring. T2 - safeND CY - Online meeting DA - 10.11.2021 KW - Distributed fiber optic radiation sensors KW - Radiation-induced attenuation KW - Optical fiber sensor KW - Incoherent optical frequency domain reflectometry PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-537531 DO - https://doi.org/10.5194/sand-1-15-2021 VL - 1 SP - 15 EP - 16 AN - OPUS4-53753 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lu, Xin A1 - Krebber, Katerina T1 - Phase error analysis and unwrapping error suppression in phase-sensitive optical time domain reflectometry N2 - Phase-sensitive optical time domain reflectometry becomes an effective tool to realize distributed sensing, and the optical phase of the received light is usually used to quantify the strain for both dynamic and static measurement. The analysis on the overall phase error has been improved by considering the proportionality of the detection noise to the local optical power. The estimation accuracy is greatly improved by using the proposed theory, the probability density of the estimation accuracy over 99% is > 0.6, ∼39 times larger than the previously reported method. The phase unwrapping may malfunction due to the noisy signal, causing large phase errors. Point break detection algorithms are used to locate the incorrect phase unwrapping points, so the temporal evolution of the phase retrieved at each position can be divided into several sections with different offset. The phase unwrapping error is then suppressed by removing the offset. KW - Phase unwrapping KW - Distributed fiber sensing KW - Acoustic sensing PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543919 DO - https://doi.org/10.1364/OE.446517 VL - 30 IS - 5 SP - 6934 EP - 6948 PB - Optica Publishing Group AN - OPUS4-54391 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lu, Xin A1 - Hicke, Konstantin A1 - Krebber, Katerina T1 - Dual functionality of wavelength scanning coherent optical time domain reflectometer N2 - Wavelength scanning coherent optical time domain reflectometer (WS-COTDR) is a good candidate to spatially resolve the environmental information at comparatively low frequency. This paper reveals it can also work as a traditional optical time domain reflectometer (OTDR) to identify Fresnel reflection by averaging the obtained signal over the wavelength scanning range. Simultaneous distributed vibration sensing and a traditional OTDR measurement are experimentally demonstrated using the WS-COTDR system. T2 - European Workshop on Optical Fibre Sensors (EWOFS 2023) CY - Mons, Belgium DA - 23.05.2023 KW - Structural health monitoring KW - Distributed fiber sensing KW - Acoustic sensing PY - 2023 DO - https://doi.org/10.1117/12.2678098 VL - 12643 SP - 1 EP - 4 PB - SPEI AN - OPUS4-57590 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lu, Xin A1 - Hicke, Konstantin A1 - Krebber, Katerina T1 - Dual-functionality of WS-COTDR for ground movement monitoring N2 - Wavelength scanning coherent optical time domain reflectometer (WS-COTDR) is a good candidate to spatially resolve the environmental information at comparatively low frequency. This paper reveals it can also work as a traditional optical time domain reflectometer (OTDR) to identify Fresnel reflection by averaging the obtained signal over the wavelength scanning range. Simultaneous distributed vibration sensing and a traditional OTDR measurement are experimentally demonstrated using the WS-COTDR system. T2 - European Workshop on Optical Fibre Sensors (EWOFS 2023) CY - Mons, Belgium DA - 23.05.2023 KW - Distributed fiber sensing KW - Acoustic sensing KW - Structural health monitoring PY - 2023 AN - OPUS4-57591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shaheen, Sabahat A1 - Hicke, Konstantin A1 - Krebber, Katerina T1 - phi-g OTDR utilizing geometric phase N2 - Geometric phase measured per beat period in a ϕ-OTDR based on coherent heterodyne detection is used to measure strain. Proposed method is robust to polarisation mismatch fading as a polarisation mismatch between interfering beams is not a hindrance to the measurement of the geometric phase. The Geometric phase is a function of the intensities of the interfering beams as well as the envelope of the beat signal. Its calculation does not require phase unwrapping and accordingly does not suffer the phase unwrapping errors. It is required to be equated with the traditionally measured phase by applying a scaling factor. The spatial resolution of the measured strain is reduced as it is calculated per beat period. Results are verified using a piezo-electric transducer inline a fiber-under-test. T2 - European Workshop on Optical Fibre Sensors (EWOFS 2023) CY - Mons, Belgium DA - 23.05.23 KW - Coherent Heterodyne KW - Geometric Phase KW - Distributed Fiber Optic Sensor PY - 2023 DO - https://doi.org/10.1117/12.2678295 SP - 1 EP - 5 PB - SPIE AN - OPUS4-57551 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Königsbauer, Korbinian A1 - Nöther, N. A1 - Schaller, M. B. A1 - Wosniok, Aleksander A1 - Krebber, Katerina T1 - Distributed POF sensors for structural health monitoring in civil construction applications N2 - In this paper, a cost-efficient distributed fiber optic measurement system based on Rayleigh scattering is presented. The distributed digital incoherent optical frequency domain reflectometry (I-OFDR) method is developed for detection of significantly large strain in the range from 3 % up to 10 % as required by end users. For this purpose, a vector network analyzer used in the I-OFDR is replaced by a compact and cost-effective digital data acquisition system. This digital emitting/receiving unit enables the recording of the complex transfer function carrying information about the local deformations along the entire sensing fiber. T2 - POF 2022 The 30th International Conference on Plastic Optical Fibers CY - Bilbao, Spain DA - 26.09.2022 KW - I-OFDR KW - PF-POF KW - Structural health monitoring KW - Rayleigh backscatter measurement KW - Strain detection PY - 2022 VL - 2022 SP - 152 EP - 155 AN - OPUS4-56060 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shaheen, Sabahat A1 - Hicke, Konstantin A1 - Krebber, Katerina T1 - Phase-sensitive optical time domain reflectometry based on geometric phase measurement N2 - A phase-sensitive optical time domain reflectometer based on coherent heterodyne detection of geometric phase in the beat signal of light, is reported for the first time to our knowledge. The use of the geometric phase to extract strain makes it immune to polarisation diversity fading. This is because a polarisation mismatch between the interfering beams is not a hindrance to its measurement. The geometric phase is calculated using the amplitude of the beat signal and individual beam intensities without any need for phase unwrapping. It is measured per beat period and can be equated with the traditionally measured dynamic phase with appropriate scaling. The results show that the system based on the geometric phase successfully measures strain, free from polarisation mismatch fading and phase unwrapping errors, providing a completely novel solution to these problems. KW - Fiber optic sensing KW - Distributed acoustic sensing KW - DAS KW - Geometric phase KW - Pancharatnam–Berry phase KW - Berry phase PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-570307 DO - https://doi.org/10.1038/s41598-023-29972-4 VL - 13 SP - 1 EP - 11 PB - Nature Portfolio CY - London AN - OPUS4-57030 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -