Distributed fibre optic sensors

Two different kinds of distributed fibre optic sensors can be distinguished ... 

Intrinsic distributed fibre optic sensors find a large application where the monitoring of a single measurand is required at a large number of points or continuously over the... 

Sumida S, Okazaki S, Asakura S, Nakagawa H, Murayama H, Hasegawa T (2005) Distributed hydrogen determination with fibre-optic sensor. Sens Actuators B 108 508-514... 

In conclusion, fibre optic sensors are ideal eandidates to be embedded in textile structural composites for monitoring manufaeturing processes and internal health eonditions. The sensors provide an effective means by whieh the distributions of a number of physieal parameters, such as temperature, stress/strain, thermal expansion, pressure, ete., ean be quantitatively determined. In integrating the sensors into textile eomposites, apart from the properties of the sensors themselves, the rehabihty of the sensors and sensing seheme as well... 

Wallace P.A., Yang Y., Campbell M., Towards a distributed optical fibre chemical sensor, SPIEProc. 2360, 465-467, (1994). 

Figure 6.69 gives an example for an optical current sensor. The light path is wound around a current-carrying conductor equidirectionally with the azimuthal magnetic field of the current. The rotation of the plane of the electric vector is not detectable on its own and is converted to light intensity variations by a polarizer/analyser combination. A photo diode is used as a light intensity detector. The optical sensor itself is installed in the - e - compartment, the electronics shall be protected in an adequate type of protection, e.g. in a small flameproof - d - enclosure or in encapsulation - m -. In the special case of an energy distribution system with combined - e - and - d - compartments, the optical fibres may enter the d-compartment to the electronics inside via bushings complying with d -standards EN 50018 or IEC 60079-1 respectively (Fig. 6.70). The evacuation of the sensors into the e-compart-ment results in additional available space in the more expensive d-compart-ment, compared with increased safety - e -. ...

The intravascular system Paratrend 7 was distributed by Diametrics Medical up to 2003 and has been the last one available on the market which assures an intravascular monitoring of pH, p02 and pC02, using an optical fibre sensor designed for arterial placement. 

J. P. Dakin, D. J. Pratt, G. W. Bibby, and J. N. Ross, Distributed optical fibre Raman temperature sensor using a semiconductor light source and detector, Electron. Lett. 21, 569 (1985). 

Roger, A.J. Shatahn, S.V. and Kanellopoulos, S.E. Distributed Measurement of Flow Pressure via Optical-fibre Backscatter Polarimetry. 17th Int. Conf. on Optical Fibre Sensors (OFS-17), Bruges, Belgium, SPIEI-VoL 5855 (2005), pp. 230-233... 

Campbell, M. et al Optimisation of Hi-birefringence Fibre Based Distributed Force Sensors. Smart Struct. Optical Instrumentation and Sensing Systems Conf. 1995, SPIE-vol. 2509 (1995), pp. 57-63... 

Philipp, L., Mario, W., Sascha, L. Katerina, K. [2010]. Distributed humidity sensing based on rayleigh scattering in polymer optical fibers. Proceedings of SPIE in Fourth European Workshop on Optical Fibre Sensors, Vol. 7653, SPIE, Porto, Portugal, p>p. 1—4. 

Figure 10.6(h) shows the reverse trends of strain distribution in the host. The strain level of the middle host is lower than that of the host near the boundary, which is because the middle host is restricted more by the fibre and the host near the boundary can expand more freely under a thermal load. The normahzed strain values of the host are very close to 1 (0.995 < e < 1), which imphes that the host with the embedded fibre sensor has a strain field very close to that without the embedded optic fibre. 

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