TY - GEN A1 - Stajanca, Pavol A1 - Krebber, Katerina ED - Kalli, K. ED - Brambilla, G. ED - O'Keeffe, S. T1 - Investigation of bare and tight-buffered optical fibers towards distributed humidity sensing N2 - Humidity is one of principal environmental parameters that plays an important role in various application areas. Using measurement of strain induced in an optical fiber by a water swellable coating represents a promising approach for realization of distributed humidity sensing (DHS). In this work, humidity and temperature response of four different commercial PI-coated fibers and four tight-buffered (TB) fibers is investigated with the aim of evaluating their potential for development of DHS in context of water ingress sensor for high-voltage power cable splices. PI-coated fibers exhibited close-to-linear humidity and temperature response. While the temperature response is relatively coating-independent, magnitude of humidity response was broadly correlated to the relative fiber-to-coating thickness ratio. In contrast, both humidity and temperature response of TB fibers is strongly influenced by buffer type, with Leoni TB900L fiber with Hytrel buffer exhibiting largest humidity and temperature sensitivity. While the response of tight-buffered fibers is generally nonlinear, roughly three-times higher humidity response can be achieved with TB900L compared to the most sensitive PI-coated fiber. Using the TB fiber can be, therefore, advantageous for simpler water detection applications, such as one targeted in this study, when larger sensitivity is more important than the linear response of the sensor. KW - Distribute fiberoptic sensor KW - Distributed humidity sensing KW - Water ingress detection KW - Optical backscatter reflectometry KW - Tight-buffered fibers KW - Polyimide-coated fibers PY - 2019 SN - 978-1-51063-124-3 DO - https://doi.org/10.1117/12.2539819 VL - 11199 SP - 111991X-1 PB - SPIE CY - Bellingham, Washington, USA AN - OPUS4-49207 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fuggini, C. A1 - Zangani, D. A1 - Wosniok, Aleksander A1 - Krebber, Katerina A1 - Franitza, P. A1 - Gabino, L. A1 - Weigand, F. T1 - Innovative approach in the use of geotextiles for failures prevention in railway embankments N2 - Maintenance and renewal costs of a typical railway, track and substructure represents 50–60% of the total costs of such infrastructure over its entire service life. Innovations in track and substructure are therefore fundamental to achieve a significant impact on the overall cost reduction for the railways. Therefore new solutions for track improvements that are effective and that can minimize the interruption of traffic are needed. Moreover, failures of railway embankments happened recently in different regions of the world. Such events, such as the one happened in UK in February 2013 (http://www.bbc.co.uk/news/uk-england-south-yorkshire-21441070), are showing the importance of monitoring track and infrastructure coupled with the use of numerical models for the localization of the critical areas and the design of appropriate countermeasures. Indeed embankment failures, landslides and uneven settlements and similar events are becoming much more common than in the past due to climate changes, and this requires the infrastructure managers to look from a different perspective infrastructure maintenance issues. What was previously consider as “extreme” is now “common” and thus actions need to be taken to be ready when such events will happen. The aim is to mitigate their effects on the infrastructure and to minimize disruptions to train services and reduce maintenance costs to restore the normal service conditions. If this mental change happens, then the need for solutions and techniques for global asset monitoring and ground stabilization will probably increase. Among the others, geotextiles and geogrids for soil reinforcement used in combination with condition monitoring techniques have the potential for minimizing catastrophic events, whilst at the same time providing a good balance among costs and benefits (i.e. sustainability). The paper describe a case study where the use of multifunctional geotextiles, able to provide both strengthening and monitoring functions, has been tested along a railroad near the city of Chemnitz (Germany). The results are here reported to show the potential use and the innovative aspect of this solution. T2 - 6th Transport Research Arena (TRA) CY - Warsaw, Poland DA - 18.04.2016 KW - smart geotextile KW - failure prevention KW - railway embankment KW - fiber optic sensor KW - distributed sensor PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-379256 DO - https://doi.org/10.1016/j.trpro.2016.05.154 VL - 14 SP - 1875 EP - 1883 PB - Elsevier B.V. AN - OPUS4-37925 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liehr, Sascha A1 - Breithaupt, Mathias A1 - Krebber, Katerina T1 - Distributed humidity sensing in PMMA optical fibers at 500 nm and 650 nm wavelengths N2 - Distributed measurement of humidity is a sought-after capability for various fields of application, especially in the civil engineering and structural health monitoring sectors. This article presents a method for distributed humidity sensing along polymethyl methacrylate (PMMA) polymer optical fibers (POFs) by analyzing wavelength-dependent Rayleigh backscattering and attenuation characteristics at 500 nm and 650 nm wavelengths. Spatially resolved humidity sensing is obtained from backscatter traces of a dual-wavelength optical time domain reflectometer (OTDR). Backscatter dependence, attenuation dependence as well as the fiber length change are characterized as functions of relative humidity. Cross-sensitivity effects are discussed and quantified. The evaluation of the humidity-dependent backscatter effects at the two wavelength measurements allows for distributed and unambiguous measurement of relative humidity. The technique can be readily employed with low-cost standard polymer optical fibers and commercial OTDR devices. KW - Optical fiber sensor KW - Humidity sensor KW - Distributed sensor KW - Polymer optical fiber KW - Rayleigh scattering PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-396363 UR - http://www.mdpi.com/1424-8220/17/4/738 DO - https://doi.org/10.3390/s17040738 SN - 1424-8220 VL - 17 IS - 4 SP - Article 738, 1 EP - 12 PB - MDPI CY - Basel, Switzerland AN - OPUS4-39636 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stajanca, Pavol A1 - Krebber, Katerina T1 - Radiation-induced attenuation of perfluorinated polymer optical fibers for radiation monitoring N2 - Due to some of their unique properties, optical fiber dosimeters are attractive and extensively researched devices in several radiation-related areas. This work evaluates the Performance and potential of commercial perfluorinated polymer optical fibers (PF-POFs) for radiation Monitoring applications. Gamma radiation-induced attenuation (RIA) of two commercial PF-POFs is evaluated in the VIS spectral region. Influence of a dose rate and temperature on RIA measurement is investigated, along with defect stability and measurement repeatability. Co-extruded PF-POFs are identified as more suitable for radiation monitoring applications due to lower dose-rate dependence. With co-extruded PF-POF, RIA measurement holds potential for highly-sensitive radiation Monitoring with good reproducibility. The results show that operation in the blue part of the spectrum provides most favorable performance in terms of the largest nominal Radiation sensitivity, lower temperature, and dose-rate dependence as well as higher defect stability. We demonstrate for the first time to our knowledge, that PF-POFs can be used for distributed detection of radiation with doses down to tens of Grays. The off-the-shelf, user-friendly PF-POF could be of interest as a cheap, disposable sensor for various applications, especially of a more qualitative nature. KW - Perfluorinated polymer optical fiber KW - Cytop KW - Ionizing radiation KW - Radiation-induced attenuation KW - Gamma radiation monitoring PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-419504 DO - https://doi.org/10.3390/s17091959 SN - 1424-8220 VL - 17 IS - 9 SP - Article 1959, 1 EP - 12 PB - MDPI AN - OPUS4-41950 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR 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 - Fabrication and characterization of polycarbonate microstructured polymer optical fibers for high-temperature-resistant fiber Bragg grating strain sensors N2 - Here we present the fabrication of a solid-core microstructured polymer optical fiber (mPOF) made of polycarbonate (PC), and report the first experimental demonstration of a fiber Bragg grating (FBG) written in a PC optical fiber. The PC used in this work has a glass transition temperature of 145°C. We also characterize the mPOF optically and mechanically, and further test the sensitivity of the PC FBG to strain and temperature. We demonstrate that the PC FBG can bear temperatures as high as 125°C without malfunctioning. In contrast, polymethyl methacrylate-based FBG technology is generally limited to temperatures below 90°C. KW - Fiber optics sensors KW - Fiber Bragg gratings KW - Microstructured fibers KW - Fiber characterization KW - Polymers PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-355591 DO - https://doi.org/10.1364/OME.6.000649 SN - 2159-3930 VL - 6 IS - 2 SP - 649 EP - 659 PB - OSA Publishig AN - OPUS4-35559 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Krebber, Katerina ED - Harun, S.W. ED - Arof, H. T1 - Smart technical textiles based on fiber optic sensors N2 - Smart technical textiles are by definition textiles that can interact with their environment. They can sense and react to environmental conditions and external stimuli from mechanical, thermal, chemical or other sources. Such textiles are multifunctional or even “intelligent” which is fulfilled by a number of sensors incorporated in the textiles. The embedded sensors are sensitive to various parameters such as temperature, strain, chemical, biological and other substances. PY - 2013 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-289397 SN - 978-953-51-1148-1 DO - https://doi.org/10.5772/54244 IS - Section 3 / Chapter 12 SP - 319 EP - 344 PB - InTech AN - OPUS4-28939 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 - TY - CONF A1 - Krebber, Katerina A1 - Liehr, Sascha A1 - Witt, Jens ED - Liao, Y. ED - Jin, W. ED - Sampson, D.D. ED - Yamauchi, R. ED - Chung, Y. ED - Nakamura, K. ED - Rao, Y. T1 - Smart technical textiles based on fiber optic sensors N2 - Smart technical textiles containing fiber optic sensors have been developed and successfully demonstrated for the purposes of the structural health monitoring in geotechnical and civil engineering as well as for healthcare monitoring in the medical sector. The paper highlights the results achieved in this innovative field in the framework of several German and European projects and shows selected examples of using such fiber-sensor-based technical textiles in different geotechnical and medical applications. T2 - OFS2012 - 22nd International conference on optical fiber sensors CY - Beijing, China DA - 15.10.2012 KW - Fiber optic sensor KW - Distributed fiber optic sensor KW - Polymer optical fibers (POF) KW - POF sensor KW - POF OTDR KW - Technical textiles KW - Geotextiles KW - Medical textiles PY - 2012 DO - https://doi.org/10.1117/12.981342 SN - 0277-786X SN - 1996-756X N1 - Serientitel: Proceedings of SPIE – Series title: Proceedings of SPIE IS - 8421 SP - 84212A-1 EP - 84212A-10 PB - SPIE, the International Society for Optical Engineering CY - Bellingham, Wash. AN - OPUS4-26915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krebber, Katerina T1 - Smart Technical Textiles Based on Fibre Optic Sensors (invited lecture) T2 - 22nd International Conference on Optical Fiber Sensors (OFS-22) CY - Beijing, China DA - 2012-10-15 PY - 2012 AN - OPUS4-26907 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mizuno, Y. A1 - Lenke, Philipp A1 - Krebber, Katerina A1 - Nakamura, K. T1 - Characterization of Brillouin gain spectra in polymer optical fibers fabricated by different manufacturers at 1.32 and 1.55 µm N2 - We characterize the Brillouin gain spectra (BGS) in perfluorinated graded-index polymer optical fibers (PFGI-POFs) at 1.32 µm and 1.55 µm. Three kinds of PFGI-POFs with the same core diameter, but which are fabricated by different manufacturers, are tested. For all the PFGI-POFs, the Stokes power measured at 1.32 µm is higher than that at 1.55 µm due to the lower propagation loss, but significant differences in Stokes power are observed among the three. Based on the measurement obtained by the optical time-domain reflectometry, we show that the actual propagation loss of the PFGI-POFs plays a crucial role in observing BGS. KW - Brillouin gain spectrum (BGS) KW - Brillouin scattering KW - Nonlinear optics KW - Polymer optical fiber (POF) PY - 2012 DO - https://doi.org/10.1109/LPT.2012.2206803 SN - 1041-1135 VL - 24 IS - 17 SP - 1496 EP - 1498 PB - IEEE CY - New York, NY, USA AN - OPUS4-26319 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krebber, Katerina A1 - Lenke, Philipp A1 - Liehr, Sascha A1 - Nöther, N. A1 - Wendt, Mario A1 - Wosniok, Aleksander A1 - Daum, Werner T1 - Structural health monitoring by distributed fiber optic sensors embedded into technical textiles N2 - Technical textiles with embedded distributed fiber optic sensors have been developed for the purposes of structural health monitoring in geotechnical and civil engineering. The distributed fiber optic sensors are based on Brillouin scattering in silica optical fibers and OTDR in polymer optical fibers. Such 'smart' technical textiles are used for reinforcement of geotechnical and masonry structures. The embedded fiber optic sensors provide online information about the condition of the structure and about the occurrence and location of any damage or degradation. N2 - Technische Textilien mit integrierten faseroptischen Sensoren eröffnen neue Möglichkeiten der Zustandsüberwachung (structural health monitoring) in Geotechnik und Ingenieurbau. Die verteilt messenden Sensoren basieren auf der Brillouin-Streuung in Glasfasern und auf der OTDR in polymeroptischen Fasern. Derartige 'intelligente' technische Textilien werden in erster Line zur Verstärkung von geotechnischen Bauwerken und von Gebäuden genutzt. Die integrierten Sensoren liefern eine zeitnahe Information über den bestimmungsgemäßen Zustand des Bauwerks sowie über die Entstehung und den Ort von lokalen Bauwerksschäden. KW - Fiber optic sensor KW - Distributed sensor KW - Brillouin scattering KW - Polymer optical fiber KW - Strain sensor KW - Smart geotextiles KW - Faseroptischer Sensor KW - Verteilter Sensor KW - Brillouin-Streuung KW - Polymeroptische Faser KW - Dehnungssensor KW - Intelligentes Geotextil PY - 2012 DO - https://doi.org/10.1524/teme.2012.0238 SN - 0340-837X SN - 0178-2312 SN - 0171-8096 VL - 79 IS - 7-8 SP - 337 EP - 347 PB - Oldenbourg CY - München AN - OPUS4-26387 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -