Quasi-static strain sensing using molecular spectroscopy

Timothy T.-Y. Lam; Jong H. Chow; Daniel A. Shaddock; Ian C.M. Littler; Gianluca Gagliardi; Malcolm B. Gray; David E. McClelland

doi:10.1117/12.884639

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17 May 2011 Quasi-static strain sensing using molecular spectroscopy

Timothy T.-Y. Lam, Jong H. Chow, Daniel A. Shaddock, Ian C.M. Littler, Gianluca Gagliardi, Malcolm B. Gray, David E. McClelland

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Proceedings Volume 7753, 21st International Conference on Optical Fiber Sensors; 77532I (2011) https://doi.org/10.1117/12.884639
Event: 21st International Conference on Optical Fibre Sensors (OFS21), 2011, Ottawa, Canada

Abstract

Steady developments in cost and reliability in fiber optic sensors have seen an increase of their deployment in numerous monitoring and detection applications. In high-end applications, greater resolution is required, especially in systems where the environment is quiet, but the signal is weak. In order to meet these requirements the most dominant noise source, laser frequency noise, must be reduced. In this paper we present a quasi-static strain sensing referenced to a molecular frequency reference. A DFB CW diode laser is locked to a fiber Fabry-Perot sensor, transferring the detected signals onto the laser frequency and suppressing laser frequency noise. The laser frequency is then read off using an H¹³C¹⁴N absorption line. Phase modulation spectroscopy is used to both lock the laser to the sensor and read off the signals detected by the sensor. The technique is capable of resolving signals below 1 nanostrain from 20 mHz, reaching a white noise floor of 10 picostrain at several Hz.

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Timothy T.-Y. Lam, Jong H. Chow, Daniel A. Shaddock, Ian C.M. Littler, Gianluca Gagliardi, Malcolm B. Gray, and David E. McClelland "Quasi-static strain sensing using molecular spectroscopy", Proc. SPIE 7753, 21st International Conference on Optical Fiber Sensors, 77532I (17 May 2011); https://doi.org/10.1117/12.884639

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