TY - CHAP A1 - Dengler, Simon Andreas A1 - Vinogradov, Juri A1 - Ziemann, Olaf A1 - Engelbrecht, Rainer A1 - Schmauß, Bernhard T1 - Low Cost POF OTDR Reaches 200 m Sensing Distance KW - Optische Polymerfaser Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:92-opus4-26577 VL - 2021 SP - 13 PB - The International Committee on Polymer Optical Fibers, ICPOF CY - Jinhua City ER - TY - CHAP A1 - Vinogradov, Juri A1 - Morf, Fabian A1 - Dengler, Simon Andreas A1 - Engelbrecht, Rainer A1 - Ziemann, Olaf T1 - FPGA and APD Based Optical Time Domane Reflectometry in Sensor Applications T2 - The 28th International Conference on Plastic Optical Fibers 2019-11-20 N2 - This paper shows an optical time domain reflectometry (OTDR) system based on an avalanche photodiode (APD) receiver, a 520 nm laser diode transmitter, a high-speed analog-to-digital converter (ADC) and a commercially available field programmable gate array (FPGA). This approach allows OTDR measurements up to 200 m and provides a spatial resolution of 20 cm. Depending on the number of averaging, the measurement time can be between 5 s and 50 s for a range up to 200 m with a good signal to noise ratio. Y1 - 2022 ER - TY - CHAP A1 - Vinogradov, Juri A1 - Kruglov, Roman A1 - Wetzel, Ulrich A1 - Engelbrecht, Rainer A1 - Ziemann, Olaf T1 - 200 m Gigabit POF Link Based on 520 nm Laser Diode and PAM Media Converter T2 - International Conference on Plastic Optical Fibers N2 - This paper shows the results on the data transmission over distances of up to 350 m SI-POF with KDPOF Media Converter based on Gigabit POF Transceiver KD1001 (KD-EVK1001MC Evaluation Kit) and laser diode (LD) operating at 520 nm. A bit rate of 1 Gbit/s with 16-PAM modulation scheme can be achieved over 200 m SI-POF. At longer distances, the bit rate is automatically reduced by KDPOF transceiver according to the actual channel capacity. Y1 - 2024 VL - Proceedings 2024 ER - TY - CHAP A1 - Vinogradov, Juri A1 - Kruglov, Roman A1 - Ziemann, Olaf A1 - Engelbrecht, Rainer T1 - Incoherent OFDR System for Distances up to 200 m SI-POF T2 - International Conference on Plastic Optical Fibers ; Proceedings 2024 N2 - We report on a proposal for an incoherent optical frequency domain reflectometry (I-OFDR) for 1-mm core diameter PMMA SI-POF. An avalanche photodiode receiver and optimized transmitter based on a 515-nm laser diode allow measurement up to 200 m SI-POF. The measurements have been carried out using a vector network analyzer; the subsequent data processing has been implemented in MATLAB. Y1 - 2024 ER - TY - CHAP A1 - Dengler, Simon Andreas A1 - Roseeu Gonzalez, R. V. A1 - Luber, M. A1 - Ziemann, Olaf A1 - Engelbrecht, Rainer A1 - Schmauss, B. T1 - Performance Evaluation of Reference Reflections in Polymer Optical Fibers for Strain Sensing T2 - 27th International Conference on Optical Fiber Sensors N2 - We present a robust concept for quasi distributed strain measurement using optical time domain reflectometry (OTDR) in polymer optical fibers (POF). The spatial shifts of discrete reflective events in the OTDR trace are evaluated as reference points. It is shown how such reference reflections can be prepared and which properties can be expected. Y1 - 2022 SN - 978-1-957171-14-2 U6 - https://doi.org/10.1364/ofs.2022.tu2.6 PB - Optica Publishing Group CY - Washington, D.C. ER - TY - CHAP A1 - Dengler, S. A1 - Schmidt, N. A1 - Luber, M. A1 - Fischer, J. A1 - Ziemann, Olaf A1 - Engelbrecht, Rainer A1 - Hangen, H. T1 - B8.3 Influence of Temperature on Distributed Strain Sensing with OTDR in Polymer Optical Fibers T2 - SMSI 2021 - Sensors and Instrumentation N2 - Strain in ground and earthworks can be measured by polymer optical fibers (POF) applied to geotextiles. We measure the increase of backscatter (IOB) in the fiber under strain using optical time domain reflectometry (OTDR). The effect of temperature on this measurement principle is investigated. The local backscatter changes by 0.003 dB/K for common ambient temperature. In addition it is shown, that temperature depended viscoelastic properties of the polymer does affect IOB. KW - optical time domain reflectometry, structural health monitoring, strain sensing, geotextiles, polymer optical fib Y1 - 2021 SN - 978-3-9819376-4-0 U6 - https://doi.org/10.5162/smsi2021/b8.3 SP - 155 EP - 156 PB - AMA Service GmbH, Von-Münchhausen-Str. 49, 31515 Wunstorf, Germany ER - TY - CHAP A1 - Rostan, Katharina A1 - Kruglov, Roman A1 - Engelbrecht, Rainer T1 - 2x2 Factorial Calibration of FBG Sensors for Simultaneous Measurement of Temperature and Humidity in PEM Fuel Cells T2 - Sensor and Measurement Science International Conference 2023 N2 - Fiber Bragg grating (FBG) sensor technology is expected to make an important contribution to extending the lifetime of polymer electrolyte membrane (PEM) fuel cells. It allows accurate measurements of in-situ operating temperature and humidity, which is essential for an accurate control of both. For these applications an accurate and reliable calibration is crucial. This paper demonstrates the successful use of a 2x2 factorial calibration method for calibration of two standard FBGs for application in a PEM fuel cell. The calibrated low-cost FBG sensor allows temperature and humidity measurements with a RMS error (RMSE) of 0.45°C and 4.8 %RH, respectively. KW - Fiber Bragg grating KW - Temperature sensing KW - Humidity sensing KW - PEM fuel cell Y1 - 2023 SN - 978-3-9819376-8-8 U6 - https://doi.org/10.5162/SMSI2023/P56 VL - 2023 SP - 388 EP - 389 PB - AMA Service GmbH, Von-Münchhausen-Str. 49, 31515 Wunstorf, Germany ER - TY - CHAP A1 - Dengler, Simon Andreas A1 - Luber, Michael A1 - Neff, Léon A1 - Hangen, Hartmut A1 - Schmauss, Bernhard A1 - Ziemann, Olaf A1 - Engelbrecht, Rainer T1 - OTDR Strain and Force Sensing by POF on Geotextiles in a Geotechnical Application Test T2 - 28th International Conference on Optical Fiber Sensors N2 - With polymer optical fibers (POF) attached to geotextiles, optical time domain reflectometry (OTDR) can be used to measure strain of the geotextile spatially resolved in soil. We test the technique in a geotechnical application test and thus demonstrate the functionality of the sensor for field use. Y1 - 2023 SN - 978-1-957171-30-2 U6 - https://doi.org/10.1364/OFS.2023.W4.91 PB - Optica Publishing Group CY - Washington, D.C. ER - TY - JOUR A1 - Weiland, J. A1 - Luber, M. A1 - Seewald, R. A1 - Schiebahn, A. A1 - Engelbrecht, Rainer A1 - Reisgen, U. T1 - Structural Health Monitoring of Adhesively Bonded Joints: Proposing a new Method by use of Polymer Optical Fibers JF - Procedia Structural Integrity N2 - According to the current state of the art, adhesively bonded joints cannot be tested completely non-destructively. This is the main motivation to permanently monitor adhesively bonded joints in order to record their structural integrity and - as a result - to ensure safe load transmission. By the use of permanent non-destructive Structural Health Monitoring (SHM) methods, structural damages in the adhesive bond can be detected at an early stage. This paper presents a new method for monitoring the structural integrity of adhesively bonded joints by integrating a Polymer Optical Fiber (POF) into the adhesive layer. The sensor concept is based on a deformation transfer from the adhesive to the POF, which results in a change in the cross-sectional shape of the POF. The cross-sectional shape influences the optical light propagation in the POF, which can be detected by simple optical measuring devices. The paper describes the general principle and first results of investigations on a structural adhesive (3M Scotch-Weld DP 609). The sensor signal is in a good relation to the stress state of the adhesive layer. KW - adhesive bonding structural health monitoring polymer optical fiber single lap joint Y1 - 2020 U6 - https://doi.org/10.1016/j.prostr.2020.11.106 SN - 2452-3216 VL - 28 SP - 1249 EP - 1257 PB - Elsevier BV ER - TY - JOUR A1 - Dengler, Simon A. A1 - Engelbrecht, Rainer A1 - Schmauss, Bernhard T1 - Absolute spectral backscatter measurements of large-core multimode PMMA polymer optical fibers JF - Optics Express N2 - To our knowledge, we are the first to measure the absolute value of the backscattering coefficient of a standard 1 mm core-diameter, multimode (MM) step-index (SI) polymethylmethacrylate (PMMA) polymer optical fiber (POF) for the spectral range of 450 nm to 700 nm. Our optical time domain reflectometer (OTDR) setup consists of a femtosecond supercontinuum laser with an acousto-optical filter as a tunable light source with short pulses and a time-correlated single-photon counting system as a receiver with a high dynamic range. The backscattering coefficient is calculated from the ratio between the energy within the fiber end reflex and the distributed backscattering level. We also measured the spectral attenuation with our OTDR setup and compared it with a standardized measurement method. At the attenuation minima within the measured spectral range the backscattering level of a 1 ns pulse is about −46 dB at 520 nm, −48 dB at 570 nm, and −51 dB at 650 nm. We were also able to show by the observed wavelength dependence that Rayleigh scattering causes a majority of the scattering. Y1 - 2021 U6 - https://doi.org/10.1364/oe.437903 SN - 1094-4087 VL - 29 IS - 21 SP - 34629 EP - 34640 PB - Optica Publishing Group ER - TY - GEN A1 - Dengler, Simon Andreas A1 - Käfferlein, Tilmann A1 - Engelbrecht, Rainer A1 - Schmauss, Bernhard A1 - Ziemann, Olaf T1 - Dependence of POF End Surface Reflectivity on Surface Roughness T2 - Proceedings POF2023 KW - Fiber optics Y1 - 2023 ER - TY - JOUR A1 - Hager, Simon A1 - Oesinghaus, Helge A1 - Bachmann, Alexander A1 - Meinardus, Martin A1 - Hofmann, Thomas A1 - Engelbrecht, Rainer A1 - Glas, Karl T1 - CaCO₃ deposits in reverse osmosis Part III – Incipient Scaling detection via polymer optical fibre sensors. Comparison to hydrochemical prediction and image analytical methods JF - Brewing Science KW - Fiber optics KW - Reverse osmosis KW - Sensor Y1 - 2023 U6 - https://doi.org/10.23763/brsc23-03hager VL - 76 IS - 3/4 ER - TY - JOUR A1 - Weiland, Josef A1 - Kunze, Billy A1 - Luber, Michael A1 - Krüger, Naomi A1 - Schiebahn, Alexander A1 - Engelbrecht, Rainer A1 - Reisgen, Uwe T1 - Structural Health Monitoring of Adhesively Bonded Pipe-to-Socket Joints by Integration of Polymer Optical Fibers and Their Load-Dependent Transmission Properties JF - Sensors N2 - Adhesively bonded pipe-to-socket joints are used in numerous industrial applications. One example is in the transport of media, e.g., in the gas industry or in structural joints for such sectors as construction, wind energy, and the vehicle industry. To monitor such load-transmitting bonded joints, this study investigates a method based on the integration of polymer optical fibers into the adhesive layer. Previous methods for monitoring the condition of pipes, such as acoustic or ultrasonic methods or the use of glass fiber optic-based sensors (FBG or OTDR), are very complex in methodology and require cost-intensive (opto-) electronic devices to generate and evaluate the sensor signals; they are therefore unsuitable for large-scale use. The method investigated in this paper is based on the measurement of integral optical transmission with a simple photodiode under increasing mechanical stress. When tried at coupon level (single-lap joint), the light coupling was varied to obtain a significant load-dependent sensor signal. Based on an angle-selective coupling of 30° to the fiber axis, a drop of 4% of the optically transmitted light power by a load of 8 N/mm2 can be detected for the adhesively bonded pipe-to-socket joint with the structural adhesive Scotch Weld DP810 (2C acrylate). KW - Fiber optics KW - Adhesive bonds KW - Sensors Y1 - 2023 U6 - https://doi.org/10.3390/s23104748 SN - 1424-8220 VL - 23 IS - 10 PB - MDPI AG ER - TY - CHAP A1 - Rostan, Katharina A1 - Kruglov, Roman A1 - Engelbrecht, Rainer T1 - Entwicklung und Charakterisierung eines Erbium-dotierten Glasfasersensors zur Temperaturmessung KW - Faseroptik Y1 - 2024 ER - TY - CHAP A1 - Engelbrecht, Rainer A1 - Rostan, K. A1 - Weiland, J. A1 - Luber, M. A1 - Schiebahn, A. A1 - Reisgen, U. T1 - Modal Distribution in Polymer Optical Fibers as Sensor for Load Monitoring in Semi-Structural Adhesive Bonds T2 - 27th International Conference on Optical Fiber Sensors N2 - PMMA polymer optical fibers embedded in semi-structural polyurethane adhesive bonds serve as economical load sensor for structural health monitoring by evaluating load-dependent optical transmission as well as modal distribution measured by a far-field camera. Scaling of sensor quantities by the sensitive fiber length is shown. Y1 - 2022 U6 - https://doi.org/10.1364/ofs.2022.w2.3 PB - Optica Publishing Group CY - Washington, D.C. ER - TY - JOUR A1 - Weiland, Josef A1 - Kunze, Billy A1 - Luber, Michael A1 - Krüger, Naomi A1 - Schiebahn, Alexander A1 - Engelbrecht, Rainer A1 - Reisgen, Uwe T1 - Structural Health Monitoring of Adhesively Bonded Pipe-to-Socket Joints by Integration of Polymer Optical Fibers and Their Load-Dependent Transmission Properties JF - Sensors N2 - Adhesively bonded pipe-to-socket joints are used in numerous industrial applications. One example is in the transport of media, e.g., in the gas industry or in structural joints for such sectors as construction, wind energy, and the vehicle industry. To monitor such load-transmitting bonded joints, this study investigates a method based on the integration of polymer optical fibers into the adhesive layer. Previous methods for monitoring the condition of pipes, such as acoustic or ultrasonic methods or the use of glass fiber optic-based sensors (FBG or OTDR), are very complex in methodology and require cost-intensive (opto-) electronic devices to generate and evaluate the sensor signals; they are therefore unsuitable for large-scale use. The method investigated in this paper is based on the measurement of integral optical transmission with a simple photodiode under increasing mechanical stress. When tried at coupon level (single-lap joint), the light coupling was varied to obtain a significant load-dependent sensor signal. Based on an angle-selective coupling of 30° to the fiber axis, a drop of 4% of the optically transmitted light power by a load of 8 N/mm2 can be detected for the adhesively bonded pipe-to-socket joint with the structural adhesive Scotch Weld DP810 (2C acrylate). KW - Fiber optics KW - Sensors KW - Adhesive bonding Y1 - 2023 U6 - https://doi.org/10.3390/s23104748 SN - 1424-8220 VL - 23 IS - 10 PB - MDPI AG ER - TY - JOUR A1 - Weiland, Josef A1 - Schiebahn, Alexander A1 - Reisgen, Uwe A1 - Luber, Michael A1 - Ziemann, Olaf A1 - Engelbrecht, Rainer T1 - Zustandsüberwachung struktureller Klebungen unter Scherbeanspruchung durch Integration einer optischen Polymerfaser JF - Schweißen und Schneiden N2 - Das im hier vorgestellten Forschungsrojekt KlebPOF untersuchte Sensorkonzept der Zustandsüberwachung von Klebungen basiert auf der Integration eines Kunststoff-Lichtwellenleiters (polymere optische Faser, POF) in die Klebung. Die ähnlichen mechanischen Eigenschaften von POF und Klebstoff, beides Kunststoffe, haben zur Folge, dass Beanspruchungen des Klebstoffs auf die POF übertragen werden. Die Auswirkungen einer Belastung auf die optischen Eigenschaften des Lichtwellenleiters werden in Bezug auf die transmittierte Lichtleistung sowie auf den Einfluss der Winkelverteilung der aus der Faser austretenden Lichtstrahlen im Fernfeld untersucht und für den Einsatz zur Zustandsüberwachung von Klebverbindungen interpretiert. Die Ergebnisse an Couponproben zeigen, dass sich die Methode insbesondere für semi-strukturelle Klebstoffe, wie zum Beispiel 2K-Polyurethane oder 2K-Methylmethacrylate und eine Beanspruchung der Klebung auf Scherung gut eignet. In den Untersuchungen an dem Funktionsmuster, einer Rohr-Muffe-Klebung, waren sehr deutliche Änderungen im Sensorsignal frühzeitig vor Versagen detektierbar. Diese Änderung konnte mit kostengünstigen opto-elektronischen Komponenten detektiert werden. Damit eignet sich die Methode für eine integrale Zustandsüberwachung der gesamten Klebung ohne Ortsauflösung, um einen kostengünstigen Sensor für den Feldeinsatz zu ermöglichen. KW - Kleben KW - Werkstoffragen Y1 - 2023 IS - 8 PB - DSV Media CY - Düsseldorf ER - TY - JOUR A1 - Fischer, Jakob A1 - Schuster, Timo A1 - Wächter, Christian A1 - Luber, Michael A1 - Vinogradov, Juri A1 - Ziemann, Olaf A1 - Engelbrecht, Rainer T1 - Isolated sensor networks for high-voltage environments using a single polymer optical fiber and LEDs for remote powering as well as data transmission JF - Journal of Sensors and Sensor Systems N2 - Abstract. Many applications in high voltage or explosive environments require sensors which are electrically isolated from other components of a system. These sensors need remote powering as well as wireless or isolated data transmission links. A possible solution can be based on optically powered optical sensor links. These typically employ four different photonic components: for the data communication a fast LED as a transmitter and a photo diode as a receiver, furthermore for sensor powering a high-power light source and a photonic power converter. Additionally, two optical fibers are required for optical remote powering and the optical data link. In this paper we demonstrate an optically powered optical sensor link using only low-cost high-brightness LEDs and a single polymer optical fiber (POF) for all of these tasks. Coupling efficiencies, power transmission and modulation bandwidths are analyzed for LEDs with different colors. Potentials for many mW of electrical remote powering and Mbit s−1 sensor data links are demonstrated over 10 m of POF. This approach can be used for almost any electronic sensor with moderate power requirements. Y1 - 2018 U6 - https://doi.org/10.5194/jsss-7-193-2018 SN - 2194-878X VL - 7 IS - 1 SP - 193 EP - 206 PB - Copernicus GmbH ER - TY - GEN A1 - Engelbrecht, Rainer A1 - Luber, Michael A1 - Vinogradov, Juri A1 - Hemmerlein, Moritz A1 - Pick, Mathias A1 - Ziemann, Olaf T1 - Field Test Results of a POF Sensor for Crack Detection in Blade Bearings of Wind Turbines T2 - Proceedings POF2024 KW - Fiber optics KW - Wind turbine KW - Sensors Y1 - 2024 ER - TY - CHAP A1 - Engelbrecht, Rainer A1 - Saur, G. A1 - Kruglov, R. T1 - B8.4 12 nm Spectral Shift with a VCSEL in the Near Infrared in a 10 µs Time Interval T2 - SMSI 2021 - Sensors and Instrumentation N2 - An optical wavelength tuning range up to 12 nm has been achieved within 10 μs, using VCSELs operating in the near infrared. The range has been measured with an interferometric setup and an optical spectrum analyzer respectively. Potentially, low-cost sensor systems based on tunable diode laser absorption spectroscopy or coherent optical frequency domain reflectometry could be realized, achieving sub-mm two-point range resolution or even better single-point range precision within a few microseconds for a single measurement. Y1 - 2021 SN - 978-3-9819376-4-0 U6 - https://doi.org/10.5162/smsi2021/b8.4 SP - 157 EP - 158 PB - AMA Service GmbH, Von-Münchhausen-Str. 49, 31515 Wunstorf, Germany ER - TY - JOUR A1 - Weiland, J. A1 - Bartholomee, W. A1 - Luber, M. A1 - Schiebahn, A. A1 - Engelbrecht, Rainer A1 - Reisgen, U. T1 - Investigation into the mechanical behavior of a polymer optical fiber embedded in a structural adhesive JF - International Journal of Adhesion and Adhesives N2 - To guaranty a safe load transfer through adhesively bonded joints, Structural Health Monitoring (SHM) methods that allow for permanent monitoring of the structural bond condition, are becoming more and more important. To meet this increasing demand, a novel approach for SHM of adhesively bonded joints by use of integrated Polymer Optical Fibers (POF) has been demonstrated in previous work. The sensor operating principle is based on strain transfer from the structural adhesive to the integrated POF. This strain transfer leads to a deformation of the POF cross-sectional shape and in that way affects the optical light propagation in the POF. In the current work, numerical and experimental results are presented into the mechanical behavior of embedded POF in adhesive bulk specimens subjected to tensile loading. Local deformations of both the POF (Asahi Kasei DB 500) and the structural adhesive (3 M Scotch Weld DP410) are evaluated using Digital Image Correlation (DIC). In the loading direction, a linear correlation is shown between strain inside the POF core and strain of the surrounding adhesive. Tests results, as well as fracture analysis, show a highly ductile behavior and failure of the POF cladding material and the interface between the POF core and annular cladding. KW - Structural health monitoring SHM Polymer optical fibers POF Epoxy Digital image correlation Finite element modelling Y1 - 2022 U6 - https://doi.org/10.1016/j.ijadhadh.2021.103018 SN - 0143-7496 VL - 117 PB - Elsevier BV ER - TY - JOUR A1 - Kruglov, Roman A1 - Saur, Gregor A1 - Engelbrecht, Rainer T1 - Precise characterization of VCSEL in the 1550 nm band having a wavelength tuning range of 12 nm within 10 µs as light sources for fast sensor systems JF - Journal of Sensors and Sensor Systems N2 - Abstract. A wavelength tuning range up to 12 nm has been achieved over 12 µs pump current pulses within a usable time of 10 µs applied to VCSELs operating in the near infrared around 1550 nm. The instantaneous optical frequency shift has been measured with an interferometric setup; the overall tuning range has then been verified with an optical spectrum analyzer. The repetition rate of the current pulses can be as high as 20 kHz with almost no influence on the sweep parameters. These results can be used for fast spectroscopic gas analysis or for rapid interferometric swept-source distance sensors. Y1 - 2022 U6 - https://doi.org/10.5194/jsss-11-161-2022 SN - 2194-878X VL - 11 IS - 1 SP - 161 EP - 169 PB - Copernicus GmbH ER - TY - CHAP A1 - Weiland, Josef A1 - Luber, Michael A1 - Rostan, Katharina A1 - Schiebahn, Alexander A1 - Engelbrecht, Rainer A1 - Reisgen, Uwe T1 - Strain Monitoring of a Structural Adhesive Bond by Embedding a Polymer Optical Fiber T2 - European Workshop on Structural Health Monitoring , Vol I N2 - In recent decades, adhesive bonding technology has become increasingly important in all industrial sectors, for example in the aerospace industry, the automotive industry or the construction industry. This is accompanied by an increased need for monitoring of adhesive bonds, especially for load-bearing, structural joints. In order to detect a possible failure at an early stage, this work is investigating a cost-effective sensor principle based on embedding of a polymer optical fiber (POF) into the adhesive layer. The strain and stress behavior of the adhesive bond are transferred to the POF and change its light-guiding properties. In the presented work, different light coupling conditions into the fiber (full excitation and angle-selective excitation) and different measurable quantities of the transmitted light decoupled from the fiber (photocurrent and far-field) are studied, to find an optimum sensor performance. The combination of a structural polyurethane adhesive with commercially available POF is investigated. The results show a high potential of the method for simple photocurrent measurement (transmission loss of 8% by half of maximum load) and an even more sensitive sensor effect for mode-dependent light power measurement. Y1 - 2022 SN - 9783031072536 U6 - https://doi.org/10.1007/978-3-031-07254-3_75 SN - 2366-2557 SP - 745 EP - 754 PB - Springer International Publishing CY - Cham ER - TY - CHAP A1 - Engelbrecht, Rainer A1 - Dengler, S. A1 - Luber, M. A1 - Fischer, J. A1 - Hangen, H. T1 - SHM at Giant Mine Heaps by OTDR Sensing with Polymer Optical Fibers BT - Chances and Challenges from Field Campaigns T2 - Optical Fiber Sensors Conference 2020 Special Edition N2 - Results from field measurement campaigns for structural health monitoring (SHM) at giant mine heaps by optical time domain reflectometry (OTDR) in polymer optical fibers (POF) are presented. Polymer geogrids built for soil reinforcement are fitted with POF for strain sensing as part of a geosynthetic sealing system designed to protect the heap from infiltration of surface water. Strain is detected by a local increase of backscatter. Measurements on eight sensor lines have been performed over a time period of six months to monitor the system behavior and potential development of or cracks within the underlying base of a sealing system. Results show the usability of this technology for strain sensing and SHM in such a harsh environment. Challenges still exist in the quantitative evaluation of the fiber sensor data due to cross sensitivity to fiber bending and lateral pressure. Y1 - 2021 U6 - https://doi.org/10.1364/ofs.2020.th4.7 PB - Optica Publishing Group CY - Washington, D.C. ER - TY - CHAP A1 - Dengler, Simon Andreas A1 - Vinogradov, Juri A1 - Engelbrecht, Rainer A1 - Schmauß, Bernhard T1 - Recent Progress in POF OTDR Strain Sensing T2 - International Conference on Plastic Optical Fibers Y1 - 2022 VL - Proceedings 2022 ER - TY - CHAP A1 - Engelbrecht, Rainer A1 - Rostan, Katharina A1 - Weiland, Josef A1 - Luber, Michael A1 - Schiebahn, Alexander A1 - Reisgen, Uwe T1 - Modal Distribution in Polymer Optical Fibers as Sensor for Load Monitoring in Semi-Structural Adhesive Bonds T2 - 27th International Conference on Optical Fiber Sensors N2 - PMMA polymer optical fibers embedded in semi-structural polyurethane adhesive bonds serve as economical load sensor for structural health monitoring by evaluating load-dependent optical transmission as well as modal distribution measured by a far-field camera. Scaling of sensor quantities by the sensitive fiber length is shown. KW - Fiber optics KW - Adhesive bonds KW - Sensors Y1 - 2022 SN - 978-1-957171-14-2 U6 - https://doi.org/10.1364/OFS.2022.W2.3 PB - Optica Publishing Group CY - Washington, D.C. ER - TY - CHAP A1 - Kruglov, Roman A1 - Engelbrecht, Rainer T1 - Rapid and High-Resolution Tunable Diode Laser Spectroscopy within 10 µs for Combustion Gas Analysis T2 - Optica Sensing Congress 2023 (AIS, FTS, HISE, Sensors, ES) N2 - We report on a rapid high-resolution absorption spectroscopy with a VCSEL reaching a peak tuning speed of 2.1 nm/µs (8.8 cm-1/µs) near 1.5 µm. An overall tuning range of up to 12 nm can be achieved within a 12 µs injection current pulse. KW - Laser spectroscopy KW - Semiconductor lasers Y1 - 2023 SN - 978-195717124-1 U6 - https://doi.org/10.1364/sensors.2023.stu2d.3 PB - Optica Publishing Group CY - Washington, D.C. ER - TY - CHAP A1 - Saur, Gregor A1 - Kruglov, Roman A1 - Engelbrecht, Rainer T1 - Microsecond Optical Frequency Tuning of DFB Laser Diodes for Coherent Optical Frequency Domain Reflectometry N2 - Optical frequency tuning ranges up to 600 GHz or 4.8 nm have been achieved within microseconds and a standard telecom DFB laser diode operating at 1550 nm. The dynamic optical frequency tuning is induced by electrical current pulse injection and measured using an interferometric setup. Potentially, low-cost sensor systems based on optical coherence tomography (OCT) or coherent optical frequency domain reflectometry (c-OFDR) could be realized, achieving sub-mm two-point range resolution or even better single-point range precision within a few microseconds for a single measurement. KW - Tunable lasers KW - Semiconductor lasers KW - Wavelength shift KW - Fiber sensing Y1 - 2020 SN - 978-3-9819376-2-6 U6 - https://doi.org/10.5162/SMSI2020/C6.2 VL - 2020 SP - 189 EP - 190 PB - AMA Service GmbH CY - Wunstorf, Germany ER - TY - GEN A1 - Engelbrecht, Rainer A1 - Dengler, Simon Andreas A1 - Luber, Michael A1 - Vinogradov, Juri A1 - Ziemann, Olaf T1 - Condition Monitoring with POF: Recent Progress on Geotextiles and Wind Turbines T2 - Proceedings POF2023 Y1 - 2023 ER - TY - CHAP A1 - Stute, Andreas A1 - Kirchbach, Lucas A1 - Giese, Andreas A1 - Bachmann, Alexander A1 - Braun, Bernd A1 - Engelbrecht, Rainer T1 - Optical Enabling Technologies for QT N2 - Overview of the research topics at TH Nuremberg for optical quantumtechnologies. Deterministic generation of NV-Centers, Integrated Spin Qubits, Micro-Optics Designs of Optical Interfaces, Lab Courses and Fabrication Devices KW - Nichtabbildende Optik KW - Stickstoff-Fehlstellenzentrum KW - Diamant KW - Integrierte Optik KW - Optik KW - Quantum KW - NV-center KW - diamond KW - spin KW - solid-state Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:92-opus4-42924 UR - https://indico.munich-quantum-valley.de/event/446/ ER - TY - CHAP A1 - Rostan, Katharina A1 - Kruglov, Roman A1 - Seiß, Volker A1 - Thiel, Susanne A1 - Eichelbaum, Maik A1 - Engelbrecht, Rainer T1 - In-situ Temperature and Humidity Measurement in PEM Fuel Cells with Off-the-shelf FBG T2 - 28th International Conference on Optical Fiber Sensors N2 - We propose a cost efficient fiber Bragg grating (FBG) sensor for measuring temperature and humidity in polymer electrolyte membrane fuel cells (PEMFC). The multiparameter sensor works with two conventional FBG and achieves an RMSE better than 0.45°C and 4.8 %RH. KW - Proton exchange membrane fuel cells KW - Temperature and humidity KW - Fiber Bragg grating Y1 - 2023 SN - 978-1-957171-30-2 U6 - https://doi.org/10.1364/OFS.2023.Tu3.36 VL - 2023 PB - Optica Publishing Group CY - Washington, D.C. ER - TY - CHAP A1 - Engelbrecht, Rainer A1 - Luber, Michael A1 - Vinogradov, Juri A1 - Hemmerlein, Moritz A1 - Pick, Mathias A1 - Ziemann, Olaf T1 - Range Extension of PMMA POF Sensors Beyond 100 M for Monitoring Large Infrastructures T2 - 33rd International Conference on Plastic Optical Fibers N2 - A POF integral length and extension sensor based on phase detection of intensity modulated light with fiber sensor lengths beyond 100 m for monitoring large infrastructures is discussed. A theory for a scaling law of the precision limit over length and modulation frequency is presented. Experimental results using green light for sensor ranges above 100 m are shown. KW - Fiber sensor KW - length sensor KW - structural health monitoring KW - large infrastructures Y1 - 2025 ER -