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- C-OTDR (2)
- Distributed vibration sensing (2)
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- Condition monitoring (1)
- DAS (1)
- DTGS (1)
- DVS (1)
- Distributed acoustic sensing (1)
- Distributed fibre optic acoustic sensing (1)
- Distributed temperature gradient sensing (1)
Organisationseinheit der BAM
We present results demonstrating several beneficial effects on distributed fiber optic vibration sensing (DVS) functionality and performance resulting from utilizing standard single mode optical fiber (SMF) with femtosecond laser-inscribed equally-spaced simple scattering dots. This modification is particularly useful when using traditional single-wavelength amplitude-based coherent optical time domain reflectometry (C-OTDR) as sensing method. Local sensitivity is increased in quasi-distributed interferometric sensing zones which are formed by the fiber segments between subsequent pairs of the scattering dots. The otherwise nonlinear transfer function is overwritten with that of an ordinary two-beam interferometer. This linearizes the phase response to monotonous temperature variations. Furthermore, sensitivity fading is mitigated and the demodulation of low-frequency signals is enabled. The modification also allows for the quantitative determination of local temperature gradients directly from the C-OTDR intensity traces. The dots’ reflectivities and thus the induced attenuation can be tuned via the inscription process parameters. Our approach is a simple, robust and cost-effective way to gain these sensing improvements without the need for more sophisticated interrogator technology or more complex fiber structuring, e.g., based on ultra-weak FBG arrays. Our claims are substantiated by experimental evidence.
Condition monitoring of industrial infrastructures using distributed fibre optic acoustic sensors
(2017)
Distributed fibre optic acoustic sensing (DAS) can serve as an excellent tool for real-time condition Monitoring of a variety of industrial and civil infrastructures. In this paper, we portray a subset of our current Research activities investigating the usability of DAS based on coherent optical time-domain reflectometry (C-OTDR) for innovative and demanding condition Monitoring applications. Specifically, our application-oriented Research presented here aims at acoustic and vibrational condition monitoring of pipelines and piping systems, of rollers in industrial heavy-duty conveyor belt systems and of extensive submarine power cable installations, respectively.
Distributed Fibre Optic Acoustic and Vibration Sensors for Industrial Monitoring Applications
(2017)
We investigate the usability of distributed fibre optic acoustic sensing (DAS) for innovative and advanced monitoring applications in industrial and civil infrastructure installations. In this paper, we report on our ongoing application-oriented research activities regarding the utilization of DAS based on coherent optical time-domain reflectometry (C-OTDR) for condition monitoring of a variety of infrastructures. Specifically, our research presented here aims at acoustic condition monitoring of and fault detection in pipelines and industrial piping systems, at acoustic condition monitoring of rollers in industrial conveyor belt installations, and at acoustic condition monitoring of and threat detection in extensive submarine power cables, respectively. Furthermore, we show a method to mitigate the effect of sensitivity fading of C-OTDR based DAS due to unstable environmental conditions via the modification of the sensor fibre. This can help to provide a continuous adequate sensor functionality for a number of different industrial monitoring applications.
We have shown that for C-ODTR based DAS two UV-inscribed scattering segments within an optical fiber have a significant influence on the local sensitivity Fading characteristics. This method was experimental proven to be suitable for distributed dynamic strain measurement in a thermally unstable environment. Signal-to-noise ratio analyses for detecting a signal peak within the time-dependent spectra were performed. Results show an increase in SNR and additionally that the occurrence of total loss of sensitivity (SNR <1) could be decreased by a factor of six when compared to an untreated standard fiber. We have shown that for C-ODTR based DAS two UV-inscribed scattering segments within an optical fiber have a significant influence on the local sensitivity Fading characteristics. This method was experimental proven to be suitable for distributed dynamic strain measurement in a thermally unstable environment. Signal-to-noise ratio analyses for detecting a signal peak within the time-dependent spectra were performed. Results show an increase in SNR and additionally that the occurrence of total loss of sensitivity (SNR <1) could be decreased by a factor of six when compared to an untreated standard fiber.