TY - CONF A1 - Liehr, Sascha A1 - Muanenda, Y. A1 - Münzenberger, Sven A1 - Krebber, Katerina T1 - Wavelength-modulated C-OTDR techniques for distributed dynamic measurement N2 - We present two wavelength-modulated coherent optical time domain reflectometry techniques for dynamic, quantitative and distributed measurement. The robust and simple techniques are based on backscattering correlations along the time axis and along the pulse wavelength shift axis. T2 - 26th International Conference on Optical Fibre Sensors OFS-26 CY - Lausanne, Switzerland DA - 24.09.2018 KW - Fiber optics sensors KW - Optical time domain reflectometry KW - OTDR KW - DAS KW - Distributed strain sensor KW - Rayleigh scattering PY - 2018 DO - https://doi.org/10.1364/OFS.2018.TuE15 SP - 1 EP - 4 AN - OPUS4-46414 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liehr, Sascha T1 - Wavelength-modulated C-OTDR techniques for distributed dynamic measurement N2 - We present two wavelength-modulated coherent optical time domain reflectometry techniques for dynamic, quantitative and distributed measurement. The robust and simple techniques are based on backscattering correlations along the time axis and along the pulse wavelength shift axis. T2 - 26th International Conference on Optical Fibre Sensors OFS-26 CY - Lausanne, Swiss DA - 24.09.2018 KW - Fiber optics sensors KW - Optical time domain reflectometry KW - Rayleigh scattering KW - Distributed strain sensor KW - Distributed vibration sensor KW - DAS PY - 2018 AN - OPUS4-46392 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Liehr, Sascha A1 - Lenke, Philipp A1 - Wendt, Mario A1 - Krebber, Katerina ED - Fu-Kuo Chang, T1 - POF sensors integrated in technical textiles for monitoring of earthwork structures and masonry T2 - Structural health monitoring 2009 - 7th International workshop on structural health monitoring CY - Stanford, CA, USA DA - 2009-09-09 KW - Distributed strain sensor KW - Optical fiber sensor KW - Geotextile KW - Technical textiles KW - POF sensor KW - Structural health monitoring KW - SHM KW - OTDR PY - 2009 SN - 978-1-60595-007-5 VL - 2 SP - 1739 EP - 1746 PB - DEStech Publications, Inc. AN - OPUS4-19960 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liehr, Sascha A1 - Wendt, Mario A1 - Krebber, Katerina ED - Jones, J. ED - Culshaw, B. ED - Ecke, W. ED - López-Higuera, J.M. ED - Willsch, R. T1 - Distributed perfluorinated POF strain sensor using OTDR and OFDR techniques T2 - 20th International conference on optical fibre sensors (Proceedings of SPIE) CY - Edinburgh, Scotland, UK DA - 2009-10-05 KW - Distributed strain sensor KW - Optical fiber sensor KW - Polymer optical fiber KW - POF sensor KW - Structural health monitoring KW - OTDR KW - OFDR PY - 2009 SN - 978-0-8194-7814-6 SN - 0277-786X SP - 75036G-1 - 75036G-4 PB - SPIE, the International Society for Optical Engineering AN - OPUS4-20289 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liehr, Sascha A1 - Lenke, Philipp A1 - Wendt, Mario A1 - Krebber, Katerina A1 - Seeger, M. A1 - Thiele, E. A1 - Metschies, H. A1 - Gebreselassie, B. A1 - Münich, J.C. T1 - Polymer optical fiber sensors for distributed strain measurement and application in structural health monitoring N2 - Polymer optical fiber (POF) sensors have the unique ability to measure high strain distributed along the fiber up to 40% using the optical time-domain reflectometry (OTDR) technique. Both, standard PMMA fibers and perfluorinated (PF) graded-index (GI) POF are introduced and evaluated in potential use and applicability. Further, distributed length change measurement based on cross-correlation analysis of the characteristic fiber signature of PF POF is introduced. We conclude the advances in distributed POF strain sensors technology with respect to application in structural health monitoring. Special focus is on the sensor integration into technical textiles for health monitoring of geotechnical structures and masonry structures. Measurement results of sensor-equipped textiles in different model tests are presented, displacement of soil and cracks in retrofitted masonry structures are detected and evaluated. KW - Distributed strain sensor KW - Optical fiber sensor KW - POF sensors KW - Structural health monitoring PY - 2009 DO - https://doi.org/10.1109/JSEN.2009.2018352 SN - 1530-437X SN - 1558-1748 VL - 9 IS - 11 SP - 1330 EP - 1338 CY - New York, NY, USA AN - OPUS4-20311 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liehr, Sascha A1 - Wendt, Mario A1 - Krebber, Katerina T1 - Distributed strain measurement in perfluorinated polymer optical fibres using optical frequency domain reflectometry N2 - We present the latest advances in distributed strain measurement in perfluorinated polymer optical fibres (POFs) using backscatter techniques. Compared to previously introduced poly(methyl methacrylate) POFs, the measurement length can be extended to more than 500 m at improved spatial resolution of a few centimetres. It is shown that strain in a perfluorinated POF can be measured up to 100%. In parallel to these investigations, the incoherent optical frequency domain reflectometry (OFDR) technique is introduced to detect strained fibre sections and to measure distributed length change along the fibre with sub-millimetre resolution by applying a cross-correlation algorithm to the backscatter signal. The overall superior performance of the OFDR technique compared to the optical time domain reflectometry in terms of accuracy, dynamic range, spatial resolution and measurement speed is presented. The proposed sensor system is a promising technique for use in structural health monitoring applications where the precise detection of high strain is required. KW - Distributed strain sensor KW - Optical fibre sensor KW - Polymer optical fibre KW - POF sensor KW - Structural health monitoring KW - OTDR KW - OFDR PY - 2010 DO - https://doi.org/10.1088/0957-0233/21/9/094023 SN - 0957-0233 SN - 1361-6501 VL - 21 IS - 9 SP - 094023-1 - 094023-6 PB - IOP Publ. Ltd. CY - Bristol AN - OPUS4-22379 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lenke, Philipp A1 - Liehr, Sascha A1 - Krebber, Katerina T1 - Improvements of the distributed strain sensor based on optical time domain reflectometry measurement in polymer optical fibers N2 - Sensing characteristics of standard polymer optical fibers (POF) are further studied using the optical time domain reflectometry (OTDR) technique. The level of the backscattering inside POF, which highly increases at locations where strain is applied to the fiber, is further investigated with respect to spectral behavior, strain rate and span of time from the stretching event. An algorithem to overcome the problem of the decrease of spatial resolution as a result of pulse broadening due to modal disperion, is proposed. The research is carried out on the background of the development of a new strain sensor that is integrated in technical textiles. T2 - 17th International Conference on Plastic Optical Fibers (POF 2008) CY - Santa Clara, California, USA DA - 2008-08-25 KW - Distributed strain sensor KW - Optical fiber sensor KW - POF KW - Scatter KW - PMMA KW - Spatial resolution PY - 2008 IS - Paper 1 SP - 1 EP - 5 AN - OPUS4-18210 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liehr, Sascha A1 - Lenke, Philipp A1 - Wendt, Mario A1 - Krebber, Katerina T1 - Perfluorinated graded-index polymer optical fibers for distributed measurement of strain N2 - Recently, we have proposed, to our knowledge for the first time, to use perfluorinated graded-index polymer optical fiber (POF) for distributed measurement of strain. Thanks to their low attenuation and low modal dispersion compared to standard-POF, this fiber type allows to extend the measurement length to more than 500 meters at increased spatial resolution. In this paper, two mechanisms for strain sensing are introduced. As in standard PMMA POF, strain in the fiber can be detected by evaluating the local backscatter increase occurring at strained fiber sections. Further, we propose, to our knowledge for the first time, a true distributed length change measurement in POF using cross-correlation analysis of the fiber’s characteristic backscatter signature. Using this technique, it is possible to measure relative displacement between different fiber sections avoiding signal fading failures that are inherent in other measurement principles. Cross-sensitivities to the sensor signal, as fiber bends and temperature, are investigated and quantified. T2 - 17th International Conference on Plastic Optical Fibers (POF 2008) CY - Santa Clara, California, USA DA - 2008-08-25 KW - Distributed strain sensor KW - Optical fiber sensor KW - Perfluorinated POF KW - POF sensors PY - 2008 IS - Paper 64 SP - 1 EP - 5 AN - OPUS4-18209 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liehr, Sascha A1 - Krebber, Katerina T1 - Application of quasi-distributed and dynamic length and power change measurement using optical frequency domain reflectometry N2 - Application results of a dynamic technique for simultaneous measurement of length changes and optical power changes between multiple reflection points in an optical fiber are presented. The technique is based on incoherent optical frequency domain reflectometry (I-OFDR) and allows for measuring for example length changes and optical power changes quasi-distributed at repetition rates up to 2 kHz. Precise measurement with length change resolutions in the µm-range can be conducted using standard single-mode or multi-mode fibers. Previous results of dynamic refractive index change measurement and the use of polymer optical fibers for high-strain measurement are concluded and possible sources of measurement inaccuracies are discussed. Field test results with sensors installed on a masonry building during a seismic shake test are presented. The versatility and simplicity of this technique makes it potentially interesting for application in the structural health monitoring sector and chemical process control. KW - Distributed strain sensor KW - Dynamic measurement KW - Optical fiber sensor KW - Refractive index sensors KW - Structural health monitoring PY - 2012 DO - https://doi.org/10.1109/JSEN.2011.2157126 SN - 1530-437X SN - 1558-1748 VL - 12 IS - 1 SP - 237 EP - 245 CY - New York, NY, USA AN - OPUS4-25565 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -