Sensing fiber optics

Preliminary research has shown that Brillouin fiber-optic sensing systems provide a possible method to detect leaks and third-party intrusion on a pipeline over distances of 25 km or more. Their intrinsic response to both temperature and mechanical strain allows for the separation of these parameters and the detection of anomalies in the scan profiles. In addition, the same sensor could be integrated into the pipeline system to detect possible ground movement relative to fixed reference points. Limited test results on surface loads associated with the intrusion of vehicles and people on a pipeline have demonstrated the sensitivity of the system and its ability to discriminate loads at different soil depths. 

G. Orellana, M. C. Moreno-Bondi, E. Segovia, M. D. Marazuela, Fiber-optic sensing of carbon dioxide based on excited-state proton transfer to a luminescent ruthenium(II) complex, Anal. Chem. 64, 2210-2215(1992). 

Baumbick, RJ. and J. Alexander Fiber Optics Sense Process Variables, Control Eng. 27, 3, 75-77 (1980). 

Abstract It has been recognized since the pioneering times of fiber-optic sensing development that the best indicator dye is worth nothing without a (polymer) support fitted... 

Vapors of polar solvents can be detected on-line by virtue of their decolorizing effect on certain blue indicator papers [155] and triphenylmethane dyes [156]. Typical vapors that can be detected are those of ethers, alcohols, esters and ketones, whereas hydrocarbons and chlorinated hydrocarbons are inert. Detection limits (with a device consisting of a yellow LED light source and a phototransistor as the detector) vary from 10 to 1000 ppm and both flowthrough cell sensing and fiber-optic sensing (via reflectometry) were found to be applicable. Response times vary from 0.5 to 4 min. 

In addition to the fiber sensors, there have been numerous reports on remote fiberless optical detection of pollution from stationary sources. Mobile remote sensors can have cost advantages over on-site instruments and also are much more versatile. Pollutants in smokestack emissions have been identified by irradiation with a laser from a mobile unit equipped with a telescope, a monochromator, and low-noise detection electronics. The gases and particles in the plume scatter the laser light in various directions. A fraction is scattered back to the receiver and analysed to detect the amount and type of gas in the plume. Many of these methods await their application to fiber-optic sensing schemes which are inherently safer than direct laser spectroscopic schemes. 

A study on distributed measurement in ship loek struetural eonstruetion monitoring using fiber optic sensing technologies... 

A fully distributed fiber optic sensing network was established to monitor strain distributions within the slope model. The layout of the sensing network is shown in Figure 3. 

The model test study verifies the capability of the fiber optic sensing network to monitor the stability of slope with high accuracy. The distributed strain monitoring results may indicate the location of the potential slip surface in the slope. 

Wang, B.J., Li, K., Shi, B., Wei, G.Q. 2009. Test on application of distributed fiber optic sensing technique into soil slope monitoring. Landslides 6(1) 61-68. 

Zhu, H.H., Yin, J.H. 2012. Fiber Optic Sensing and Performance Evaluation of Geo-Structures. Saarbriicken Lambert Academic Publishing AG Co KG. 

PDT-COIL s cross-section. The fiber optics sensing SMART profiies are designated by SP-A, SP-B and SP-C (inaudi and Glisic, 2010). 

Inaudi D, Glisic B (2010) Long-range pipeline monitoring by distributed fiber optic sensing . Journal of Pressure Vessel Technology, Transactions of the ASME, 132(1), 0117011-0117019. 

Other technologies that have been used for atmospheric corrosion sensing include electrical resistance (ER) sensors and more recently fiber-optic sensing systems. Additional information may be found on this topic in Chap. 6, Corrosion Maintenance Through Inspection and Monitoring. 

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