Abstract
We present numerical and experimental results on a new generation fibre optic perimeter sensor based on a Sagnac and Michelson interferometers configuration. In particular, an original signal processing scheme is presented. The sensor can detect a potential intruder and determine its position along a protected zone. We propose a localization method that offers the inherent properties of both interferometers. After demodulation of the signals from both interferometers, the obtained amplitude characteristic of the Sagnac interferometer depends on a position of a disturbance along the interferometer, while amplitude characteristic of the Michelson interferometer does not depend on this position. So, quotient of both demodulated characteristics makes it possible to localize the disturbance. During investigations of a laboratory model of the sensor, it was possible to detect the position of the disturbance with a resolution of about 40 m along the 6-km-long sensor.
[1] J.P. Dakin, D.A.J. Pearce, A.S. Strong, and C.A. Wade, “A novel distributed fibre sensing system enabling location of disturbance in Sagnac loop interferometer”, J. Optical Sensors 2, 403–406 (1982). Search in Google Scholar
[2] A.A. Chtcherbakov, P.L. Swart, and J.S. Spammer, “A fibre optic disturbance localization sensor using modified Sagnac and Mach-Zehnder interferometers”, Conf. OFS-12, 516–519 (1997). 10.1364/OFS.1997.OThC28Search in Google Scholar
[3] A.A. Chtcherbakov, P.L. Swar, and J.S. Spammer, “Dual wavelength Sagnac-Michelson distributed optical fibre sensor”, Proc. SPIE 2838, 301–307 (1996). http://dx.doi.org/10.1117/12.25981210.1117/12.259812Search in Google Scholar
[4] E. Ronnekeiv, K. Blotekjer, and K. Krakenes, “Distributed fibre sensor for location of disturbances”, Inter. Conf. OFS-9, Post-deadline paper No. 7, 1993. Search in Google Scholar
[5] E. Udd, “Sagnac interferometer based secure communication systems”, Inter. Conf. OFS-1, 594–597 (1996). 10.1364/OFS.1996.Th344Search in Google Scholar
[6] S.J. Russell and J.P. Dakin, “Location of time-varying strain disturbances over a 40-km fibre section, using a dual-Sagnac interferometer with a single source and detector”, Proc. SPIE 3746, 580–583 (1999). Search in Google Scholar
[7] B. Griffiths, “Development in and applications of fibre optic intrusion detection sensors”, Proc. IEEE, 325–330 (1995). Search in Google Scholar
[8] A.D. Kersey, “Recent progress in interferometric fibre sensor technology”, Proc. SPIE 1367, 2–12 (1991). http://dx.doi.org/10.1117/12.2472410.1117/12.24724Search in Google Scholar
[9] B. Chiu and M.C. Hastings, “Digital demodulation for passive homodyne optical fibre interferometry based on a 3×3 coupler”, Proc. SPIE 2292, 371–381 (1994). http://dx.doi.org/10.1117/12.19185210.1117/12.191852Search in Google Scholar
[10] S.J. Spammer, P.L. Swart, and A.A. Chtecherbakov, “Merged Sagnac-Michelson interferometer for distributed disturbance detection”, JoLT 15, 972–977 (1997). Search in Google Scholar
[11] M. Szustakowski, M. Kondrat, M. Życzkowski, and N. Pałka, “Conception of sensors for fibre optic cables monitoring”, Proc. 5 th NATO Regional Conference on Military Communications and Information Systems, Zegrze, Poland, 6 (2003). Search in Google Scholar
[12] M. Szustakowski, M. Chojnacki, and M. Życzkowski “Fibre optic distributed sensor of vibration in unbalanced Michelson interferometer configuration”, Opto-Electron. Rev. 9, 413–418 (2001). Search in Google Scholar
[13] B. Chiu and M.C. Hastings, “Digital demodulation for passive homodyne optical fibre interferometry based on 3×3 coupler”, Proc. SPIE 2292, 371–382 (1994). http://dx.doi.org/10.1117/12.19185210.1117/12.191852Search in Google Scholar
[14] I.J. Bush and D.R. Sherman, “High performance interferometric demodulation techniques”, Proc. SPIE 1795, 412–420 (1992). http://dx.doi.org/10.1117/12.14127610.1117/12.141276Search in Google Scholar
[15] B. Culshaw and J. Dakin, “Optical fiber sensors”, Proc. SPIE 5855, 419–422 (2005). http://dx.doi.org/10.1117/12.62366710.1117/12.623667Search in Google Scholar
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