A System Design Perspective for Measurement of Parameters Using Different Scatterings Associated with Fibre Optic Sensors

Abstract

Fibre optic sensors offer enormous advantages over conventional sensors like immune to harsh and hazardous environments, transmission without losses, and easy integration in structures that make them a great substitute. Distributed fibre optic sensors (DFOS) allow measurement all along the fibre length and provide continuous measurement of physical parameters like temperature, pressure, vibration and strain. They can be easily implemented in coalmines, tunnels, pillars, etc., for structural health monitoring, for pipeline leakage detection and for scaling detection in distillation towers, boilers, furnaces, etc. This paper illustrates the working principle of the DFOS and the various scattering schemes utilised in DFOS for sensing the parameters. The paper provides clear understanding and important considerations needed for the conceptual design of the DFOS system using different scatterings. It also brings out the clear differences in the scattering schemes from which it can be concluded that the Brillouin scattering can be used for temperature and strain measurements, and it is implemented for long distances. Raman scattering provides better sensitivity to temperature but can be employed for shorter distances, and Rayleigh scattering can be used for dynamic measurements. Though DFOS are utilised in many commercial fields but still has to make its impact in the market due to its huge overall cost. With the advancement in the electronics and instrumentation technology, many new economical devices will help reduce this economical hindrance and make DFOS beneficial to the society.KeywordsDistributed fibre optic sensorsBackscatteringOptical time domain reflectometerRayleigh scatteringRaman scatteringBrillouin scatteringStokesAnti-Stokes