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Johannes Roths
Munich University of Applied Sciences
OpticsMaterials scienceOptical fiberFiber Bragg gratingFiber
55Publications
6H-index
125Citations
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Publications 58
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#1Markus LindnerH-Index: 2
Last. Johannes RothsH-Index: 6
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In this study, the response of regenerated fiber Bragg gratings (RFGBs) to axial forces was investigated in a temperature range from room temperature to 900 °C. For the first time, the transition from pure elastic to viscoelastic behavior around 700 °C of a standard SMF28 optical fiber was measured with an inscribed RFBG. An elastic model with linear temperature dependencies of Young’s modulus and Poisson’s ratio was established, and showed good agreement with the measurements up to temperatures...
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#1Franz J. DutzH-Index: 1
#2Andreas HeinrichH-Index: 1
Last. Johannes RothsH-Index: 6
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A low-drift fiber-optic sensor system, consisting of 24 regenerated fiber Bragg gratings (RFBG), equally distributed over a length of 2.3 m, is presented here. The sensor system can monitor spatially extended temperature profiles with a time resolution of 1 Hz at temperatures of up to 500 °C. The system is intended to be used in chemical reactors for both the control of the production ramp-up, where a fast time response is needed, as well as for production surveillance, where low sensor drifts o...
1 CitationsSource
#1Gaopeng WangH-Index: 8
#2Shiwen YangH-Index: 2
Last. Minghong YangH-Index: 19
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α-MoO3 has been used as a hydrogen sensing material due to its excellent properties and unique crystalline layer structure. However, the low repeatability of α-MoO3 based hydrogen sensor restricts its practical application. In this paper, the effect of intercalated ion species and the amount in α-MoO3 is experimentally investigated and discussed. It is concluded that the repeatability of the sensor depends on the radius of intercalated ions and amount of ionic bonds. The optimal ion species is N...
1 CitationsSource
#1Gabriele Marchi (Munich University of Applied Sciences)H-Index: 4
#2Peter Foehr (TUM: Technische Universität München)H-Index: 7
Last. Johannes Roths (Munich University of Applied Sciences)H-Index: 6
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Abstract Objective In this study we aim to show that an optical fiber Bragg grating-based microindentation system, which has the potential to be deployed arthroscopically, can differentiate between healthy and degenerated articular cartilage, which represents an important challenge in minimally-invasive surgery. Design Twenty bovine osteochondral cylinders, extracted from the patellar groove of ten 24 months old animals were subjected to stepwise in vitro stress-relaxation indentation measuremen...
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#1Gaopeng Wang (WUT: Wuhan University of Technology)H-Index: 8
#2Yuhuan Qin (WUT: Wuhan University of Technology)H-Index: 4
Last. Minghong Yang (WUT: Wuhan University of Technology)H-Index: 19
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Abstract A novel fiber Bragg grating (FBG) hydrogen sensor based on WO 3 -Pd 2 Pt-Pt composite film and controllable laser heating system is proposed and experimentally demonstrated with improved performance. The hydrogen sensor is a small stainless steel tube with two gas holes. The stainless steel tube contains two single mode fibers. One is inscribed with two short-period FBGs for monitoring the hydrogen concentration and ambient temperature, and the other is linked with 980 nm laser for opti...
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#1Markus LindnerH-Index: 2
Last. Johannes RothsH-Index: 6
view all 5 authors...
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#2Gabriele MarchiH-Index: 4
Last. Johannes RothsH-Index: 6
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#1Gabriele Marchi (Munich University of Applied Sciences)H-Index: 4
#2Peter Foehr (TUM: Technische Universität München)H-Index: 7
Last. Johannes Roths (Munich University of Applied Sciences)H-Index: 6
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In this study, the capability of a fiber optic microindenter sensor to discriminate between healthy and slightly degenerated human articular cartilage samples is demonstrated. The purely optical indenter sensor is characterized by extremely reduced dimensions (0.125 mm in diameter and 27 mm in length) in comparison to existing indenter probes offering advantages for endoscopic deployment. The indenter sensor is intended to assist the surgeon in the identification of damaged articular cartilage. ...
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#1Florian Heilmeier (TUM: Technische Universität München)H-Index: 2
#2R. Koos (TUM: Technische Universität München)H-Index: 2
Last. Wolfram Volk (TUM: Technische Universität München)H-Index: 13
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Fibre Bragg Gratings (FBGs) were employed as internal strain sensors within tensile specimens that were machined out of a casted aluminium alloy. Embedded FBGs have the potential to directly measure strains within a casted part for a better understanding of load cases for the part design process. In addition, if the FBGs remain in the part, strains can be measured under real-life conditions and return valuable evidence for health monitoring. The proof of application is provided by the presented ...
1 CitationsSource
#1Barbara HopfH-Index: 3
#2Bennet FischerH-Index: 1
Last. Johannes RothsH-Index: 6
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A novel technique for strain and temperature decoupling with surface-glued fiber Bragg gratings (FBGs) is presented and applied for strain-independent temperature measurements in a temperature range between −30 °C and 110 °C with uncertainties below 4 °C over the entire measurement range. The influence of temperature-dependent glue-induced transversal forces on the fiber sensor could be eliminated with a sensor element consisting of two FBGs in identical polarization-maintaining fibers that were...
2 CitationsSource
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