Fiber Bragg Grating Temperature Sensor System on a Twin-Deck Continuous Rigid Frame Bridge for Long Term Monitoring

Wang, Lei; Li, Dongsheng; Ou, Jin Ping

doi:10.4028/www.scientific.net/amr.148-149.1611

Cited by 2 publications

(1 citation statement)

References 15 publications

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“…It is suitable for WDM and will not disturb signal transmission. So it can be packaged into various sensors which are widely used in the monitoring of structural health, large mechanical equipment, physical quantity of severe environment, and so forth [1]. As technology evolves, FBG demodulation systems are required to measure the change of FBG reflection wavelength with higher speed and resolution in a wider optical spectrum range [2].…”

Section: Introductionmentioning

confidence: 99%

Research of High-Speed FBG Demodulation System for Distributed Dynamic Monitoring of Mechanical Equipment

Tang

et al. 2013

Advances in Mechanical Engineering

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This paper designs and implements the high-speed FBG demodulation system which can demodulate multiple FBG sensors (up to 64 sensors in series per channel) of 4 channels synchronously. The system is based on the method of tunable F-P filter. Both the nonlinear effect and the temperature drift effect of the F-P filter are eliminated by applying the triangular-like drive signal and reference channels. In addition, a high-speed adaptive algorithm for peak-find is designed for the system. The experiment results show that, for the whole system, the stability is 2 pm, the resolution is 1 pm, the linearity is 0.999, the measurement precision is 20 pm, and the demodulation frequency is 4 kHz. Consequently, the system is very suitable for distributed dynamic monitoring of complicated mechanical equipment.

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Section: Introductionmentioning

confidence: 99%

Research of High-Speed FBG Demodulation System for Distributed Dynamic Monitoring of Mechanical Equipment

Tang

et al. 2013

Advances in Mechanical Engineering

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High speed demodulation method of identical weak fiber Bragg gratings based on wavelength-sweep optical time-domain reflectometry

Wang¹,

Chen-Chen²,

Liu³

et al. 2016

Acta Phys. Sin.

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The identical weak reflection Fiber Bragg gratings (FBGs) with large capacity has become one of the central issues of optical fiber sensing field in the engineering application.Currently,wavelength division multiplexing (WDM) and time division multiplexing (TDM) are two major multiplexing techniques.For a WDM system,the maximum number of FBGs is limited by the spectral bandwidth of laser.So the identical weak FBGs are proposed to break through the limitation of the multiplexing capacity.For large-capacity multiplexing of identical weak FBGs,TDM technique is commonly used.In a TDM system,the spectral information of all FBGs can be obtained by some pulsed light with different wavelengths.However,with increasing the number of identical weak FBGs in TDM system,some problems such as complex demodulation process and slow response time are highlighted in the current various demodulation methods. Thus in this paper we propose a new high-speed demodulation method combined with wavelength-sweep optical timedomain reflectometry (WSOTDR) which is different from the pulsed light in optical time domain reflectometry (OTDR), namely a continuous wavelength-sweep light source is used in WSOTDR.In this method,the reflected signals of identical weak FBG at each position will be distinguished from others in time domain through optical delay effect,hence the location information of each FBG could be acquired,and meanwhile the wavelength information of all the identical weak FBGs could be obtained through high-frequency periodical wavelength-swept spectrum in just one wavelength scanning period.In order to calibrate the error of FBG demodulation which is caused by optical delay at high-speed wavelength sweep,we propose a self-calibration method in which two different wavelength-sweep rates are used to obtain the inherent delay parameters of each FBG.In practical application,we use this self-calibration method in the initial stage of demodulation because the inherent delay parameters are usually stable after the layout of an identical weak FBGs network.So the demodulating speed at the working stage of this system is not affected by this self-calibration method. In this paper,by setting up a Fourier domain mode locking laser as an output of continuous wavelength-sweep and highspeed (3.27×106 and 2.72×106 nm/s) light,an identical weak FBG sensing network which consists of 18 FBGs is tested in three experiments.In the initial calibration experiment,we use the self-calibration method to calibrate the inherent delay parameters of each FBG and to verify the accuracy of the system by comparing with the measurement result of spectrum analyzer.In the temperature experiment,the wavelength of each FBG is demodulated from 30 to 100 ℃ in order to test the demodulation linearity of the system.Then in the vibration experiment,a dynamic measurement of 3.6 kHz vibration of FBG is demonstrated with a demodulating speed as fast as 120 kHz,and a 0-60 kHz frequency spectrum is analyzed to prove the speed.The experimental results show that the demodulation error is less than 15 pm, the resolution is 1pm,the linearity is above 0.998,and the demodulating speed reaches 120 kHz.

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Fiber Bragg Grating Temperature Sensor System on a Twin-Deck Continuous Rigid Frame Bridge for Long Term Monitoring

Cited by 2 publications

References 15 publications

Research of High-Speed FBG Demodulation System for Distributed Dynamic Monitoring of Mechanical Equipment

Research of High-Speed FBG Demodulation System for Distributed Dynamic Monitoring of Mechanical Equipment

High speed demodulation method of identical weak fiber Bragg gratings based on wavelength-sweep optical time-domain reflectometry

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