High spatial resolution distributed optical fibre dynamic strain sensor with enhanced frequency and strain resolution

A distributed optical fiber dynamic strain sensor with high spatial and frequency resolution is demonstrated. The sensor, which uses the φ-OTDR interrogation technique, exhibited a higher sensitivity thanks to an improved optical arrangement and a new signal processing procedure. The proposed sensing system is capable of fully quantifying multiple dynamic perturbations along a 5 km long sensing fiber with a frequency and spatial resolution of 5 Hz and 50 cm, respectively. The strain resolution of the sensor was measured to be 40 nε

Distributed optical fibre sensing with enhanced frequency range and sensitivity for structural health monitoring

A distributed optical fibre sensing system is studied which uses a PZT to modulate the phase of the backscattered Rayleigh light in order to enhance the frequency range and strain sensitivity of the sensing system

Performance comparison between Raman and Brillouin intensity based sub metre spatial resolution temperature compensated distributed strain sensor

With the capability of Brillouin Optical Correlation Domain Analysis (BOCDA) technique to probe measurands with millimeter order spatial resolution [1], the idea of combining intensity measurements with BOCDA for high spatial resolution temperature compensated distributed strain sensing has been explored and successfully demonstrated [2, 3]. This paper discusses the advantages of achieving this temperature compensation using Raman [2] or Brillouin intensity measurements [3]. Fig. 1 shows a summary of temperature compensation strain measurements made using Raman/Brillouin intensity in combination with Brillouin frequency based BOCDA. The 131m long sensing fibre comprised a 42m unheated-unstrained section, 14.5m of unstrained section maintained at 52°C, 33m unheated-unstrained section, 3.5m unheated section subject to 1044 µ.epsilon over a fibre strain rig and 38m unheated-unstrained section of standard single mode telecommunications fibre

Distributed optical fibre acoustic sensors – future applications in audio and acoustics engineering

First successful experiments with optical fibre acoustic sensors were performed in 1970s by Bucaro et al.1 and Cole et al.2. Those and later developments were primarily concerned with point sensors which are equivalent to single microphone or a microphone array with fixed number of microphone. Optical fibre acoustic sensors utilise pressure induced variations in the refractive index of the fibre and its geometrical deformation caused by flexural wave to measure acoustic disturbance3. Single point optical fibre acoustic sensors are usually more expensive than microphones. However, if a large number of sensors is needed, distributed optical fibre sensors can offer a cost-effective alternative to microphone array due to the possibility of mapping the sound pressure level as a function of distance. Historically the oldest application of distributed optical fibre sensors (DOFS) were to measure the integrity of optical fibres along long telecom optical links. Just recently the focus has shifted towards distributed measurements of sound and vibration4. This paper briefly reviews the optical fibre distributed acoustic sensor technology. First, we look into distributed sensing principles in more details and compare different methods. In the next section,we will discuss the principle of Phase Optical Time Domain Reflectometry (phi-OTDR) and Rayleigh backscattering, which is used in the system designed and built by Masoudi et al.5. We will discuss the limitations of the system from acoustics point of view. Then, we propose possible applications of such a system in acoustic measurements. In sections 4–6, the results of the preliminary experiment performed in a reverberation chamber are presented and discussed

High frequency current sensing using optical fiber micro-wire

Fiber-optic current sensors exploiting the Faraday effect have attracted a great deal of interest due to their wide dynamic range, robustness and remote sensing capability. Recently a new approach to current sensing using optical fiber micro-wire (OFM) with 5µm diameter in the configuration of a micro-coil (MC) has been proposed and successfully demonstrated [1]. It featured high compactness, robustness, configurability and excellent confinement of light and was able to demonstrate its ability to sense currents with a 1µs rise time. In this paper we present a major improvement in the current sensing bandwidth, demonstrating a capability to detect a fast current pulse with pulse width (full width at half maximum: FWHM) of 6.7ns

Novel optical fibre distributed temperature sensor based on the Landau-Placzek ratio

We report our latest results on a compact, diode pumped optical fibre distributed temperature sensor based on Brillouin scattering. A high power, short pulse Q-switched Erbium/Ytterbium fibre laser and a double pass in-fibre Mach-Zehnder interferometer make this Brillouin distributed temperature sensor an attractive commercial device. A spatial and temperature resolution of 10 metres and + or - 1.7°C has been demonstrated

Numerical modelling of distributed vibration sensor based on phase-sensitive OTDR

A Distributed Vibration Sensor Based on Phase-Sensitive OTDR is numerically modeled. The advantage of modeling the building blocks of the sensor individually and combining the blocks to analyse the behavior of the sensing system is discussed. It is shown that the numerical model can accurately imitate the response of the experimental setup to dynamic perturbations a signal processing procedure similar to that used to extract the phase information from sensing setup

Dataset for High spatial resolution distributed optical fibre dynamic strain sensor with enhanced frequency and strain resolution

Excel data representing the diagrams in the letter: &quot;High spatial resolution distributed optical fibre dynamic strain sensor with enhanced frequency and strain resolution&quot; Authors: Ali Masoudi and Trevor P. Newson Optics Letters The data in the excel document contains the data points of the diagrams shown in figure 3~5 of the letter: Linearity tab contains the datapoints for the linearity plot in figure 3; Frequency Response tab contains the datapoints for the PZT frequency response measured by the sensor and the MZI and which is shown in figure 4; Frequency Resolution and Spatial resolution data in the last two tabs contain the data points for the spatial and frequency resolution of the sensor shown in figure 5(a) and 5(b), respectively.</span