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31 May 1999 Precision of a Brillouin-scattering-based distributed strain sensor
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Abstract
Distributed fiber optic sensors based on Brillouin scattering are capable of measuring the strain on an arbitrary fiber section. Their small cross section and ability to sense over a long distance makes them ideally suited for use as a sensing component in smart civil and aerospace structures. Over the past few years, the sensing range and spatial resolution of Brillouin systems have been improved considerably. It has been speculated that linewidth broadening and diminishing signal strength for optical pulses less than 10 ns would limit the spatial resolution of a Brillouin sensor to about 1 m. While this is suitable for some applications, others would benefit from improved spatial resolution. Through numerical simulation we have determined the contributions that linewidth broadening and reduced signal strength have on sensing accuracy. Experimentally, we have discovered that while the signal strength does decrease linearly with pulse widths, the linewidth does not increase correspondingly. Instead, it was observed that at pulse widths below about 5 ns the linewidth decreases dramatically. By improving the signal to noise ratio in our system we have achieved a spatial resolution of 100 mm. At this resolution the Brillouin linewidth is approximately 50 MHz, about the same as the steady state linewidth.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Anthony W. Brown, Michael D. DeMerchant, Xiaoyi Bao, and Theodore W. Bremner "Precision of a Brillouin-scattering-based distributed strain sensor", Proc. SPIE 3670, Smart Structures and Materials 1999: Sensory Phenomena and Measurement Instrumentation for Smart Structures and Materials, (31 May 1999); https://doi.org/10.1117/12.349747
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