Distributed temperature sensing in solid-core fibres

Hartog, Arthur H.; Leach, A.P.; Gold, M.P.

doi:10.1049/el:19850752

Cited by 154 publications

(66 citation statements)

References 3 publications

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“…Raman distributed optical fibre sensors are intensity-based systems 1,2 , and therefore the precision in the obtained temperature profile depends directly on the SNR of the measured Raman anti-Stokes and Stokes (or Rayleigh) traces. The here reported method increases the SNR of time-domain Raman traces, and therefore the temperature accuracy of the sensor, by using a 2D denoising approach based on image processing 9,10 .…”

Section: Denoising One-dimensional Time-domain Raman Traces With 2d Imentioning

confidence: 99%

“…After three decades of research and development, Raman distributed optical fibre sensing 1,2 is nowadays the most mature and consolidated technology for distributed temperature measurements. The time-domain interrogation approach requires launching high-power optical pulses into a sensing fibre, while the spontaneous Raman anti-Stokes backscattered intensity is measured as a function of the fibre location 1,2 .…”

Section: Introductionmentioning

confidence: 99%

“…The time-domain interrogation approach requires launching high-power optical pulses into a sensing fibre, while the spontaneous Raman anti-Stokes backscattered intensity is measured as a function of the fibre location 1,2 . To compensate for potential laser power fluctuations and some local fibre losses, temperature-dependent Raman anti-Stokes traces are typically normalized by temperature-independent Rayleigh 2 or Raman Stokes 1 traces. Following a calibration procedure, a distributed temperature profile can be obtained along several kilometres of optical fibre with a spatial resolution of a few metres.…”

Section: Introductionmentioning

confidence: 99%

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Reaching millikelvin resolution in Raman distributed temperature sensing using image processing

2016

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Image processing is proposed and experimentally demonstrated to improve the capabilities of Raman distributed optical fibre sensors. The here reported technique consists in stacking consecutive one-dimensional Raman Stokes and anti-Stokes traces in two-dimensional data arrays (one for each Raman component), which are then processed by an image denoising algorithm. Owing to the high level of correlation between consecutive measurements in conventional Raman sensing, it is experimentally demonstrated that this newly-proposed two-dimensional denoising approach provides a significant signalto-noise ratio improvement, which in this case reaches 13.6 dB with no hardware modification to the conventional set-up. Experimental results demonstrate Raman distributed sensing with a remarkably enhanced temperature resolution of 4 mK at 9 km distance, which is obtained with 2 m spatial resolution and a short acquisition time of 35 s.

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Section: Denoising One-dimensional Time-domain Raman Traces With 2d Imentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reaching millikelvin resolution in Raman distributed temperature sensing using image processing

2016

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“…The Brillouin frequency shift is dependent on both temperature and strain, whereas the Raman signal is only sensitive to temperature. Moreover, the intensity of the Raman signal exhibits more sensitivity to temperature (∼0.8%/ • C) [3] than the anti-Stokes Brillouin signal (∼0.36%/ • C) [2] . Thus, the Brillouin intensity can be replaced by the Raman intensity.…”

mentioning

confidence: 99%

“…The interaction between the Brillouin backscattered signal and LO generates a Brillouin-shifted frequency signal, which is detected by the coherent detection system. The anti-Stokes Raman signal is only sensitive to temperature, and the Raman intensity change is proportional to the temperature change [3] . Thus, the anti-Stokes Raman intensity change obtained from the direct detection system can be expressed as where L is the distance along the fiber, ∆T R (L) is the temperature variation, and C T R is the temperature coefficient of the Raman intensity change.…”

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confidence: 99%

Dual-source distributed optical fiber sensor for simultaneous temperature and strain measurements

Chen

Zhang

et al. 2012

中国光学快报

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A dual-source distributed optical fiber sensor system with combined Raman and Brillouin scatterings is designed for simultaneous temperature and strain measurements. The optimal Raman and Brillouin signals can be separately obtained by adjusting the powers of the two sources using an optical switch. The temperature and strain can be determined by processing the optimal Raman and Brillouin signals. The experimental result shows that 1.7• C temperature resolution and 60-µε strain resolution can be achieved at a 24.7-km distance.OCIS Recently, intensive research has been aimed at the development of distributed optical fiber sensors (DOFSs) because of their notable advantages such as continuous strain and temperature measurements, and strong resistance to electromagnetic interference and corrosion. Some primary applications have been made in monitoring large structures such as dams, tunnels, pipelines, oil wells, bridges, landslides, etc [1] . In the DOFS system based on the Brillouin optical time domain reflectometry (BOTDR) technique, temperature and strain variations can be measured using the Brillouin frequency shift combined with a change in Brillouin intensity. However, the accuracy of the intensity measurement limits the performance of long-range combined temperature and strain sensors [2] . The Brillouin frequency shift is dependent on both temperature and strain, whereas the Raman signal is only sensitive to temperature. Moreover, the intensity of the Raman signal exhibits more sensitivity to temperature (∼0.8%/ • C) [3] than the anti-Stokes Brillouin signal (∼0.36%/ • C) [2] . Thus, the Brillouin intensity can be replaced by the Raman intensity. The temperature along the fiber can be determined using the Raman intensity, whereas the strain can be computed using the Brillouin frequency shift. Commercial Raman distributed temperature sensors can now readily achieve 1• C temperature resolution for a 30-km distance [4] . Therefore, the temperature resolution and strain would be greatly improved if the Raman distributed temperature sensor is combined with Brillouin frequency measurement. In this letter, we propose a method for measuring the anti-Stokes Raman intensity and Brillouin frequency shift generated from dual sources with optimal output optical power to obtain the temperature and strain along the fiber.The DOFS system for simultaneous temperature and strain measurements is shown in Fig. 1. The seed laser light radiated from the distributed feedback laser diode (DFB-LD) is split using a 90/10 coupler, with 10% of the power used to produce the local oscillator (LO) for coherent detection and 90% of the power amplified by the erbium-doped fiber amplifiers (EDFAs). The continuous light is converted to pulse light using the acoustooptic modulator (AOM) and amplified using EDFA2. After passing through the circulator (C1), the pulse light is launched into the fiber for measurement. The polarization scrambler (PS) is used to reduce polarization noise [5] . The spontaneous Raman and Brillouin backscattered signa...

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