Swept-wavelength Interferometric Interrogation of Fiber Rayleigh Scatter for Distributed Sensing Applications
Short Summary
We review recent advancements in making high resolution distributed strain and temperature measurements using swept-wavelength interferometry to observe the spectral characteristics of Rayleigh scatter in optical fibers.
Abstract
We review recent advancements in making high resolution distributed strain and temperature measurements using swept-wavelength interferometry to observe the spectral characteristics of Rayleigh scatter in optical fibers. Â Current methods available for distributed strain or temperature sensing in optical fiber include techniques based on Raman, Brillouin, and Rayleigh scattering. Â These techniques typically employ optical time domain reflectometry and are thus limited in spatial resolution to 0.1 to 1 m. Â Fiber Bragg gratings can yield higher spatial resolution but are difficult to multiplex in large numbers for applications requiring wide scale coverage. Â Swept-wavelength interferometry allows the Rayleigh scatter amplitude and phase to be sampled with very high spatial resolution (10s of microns). Â The Rayleigh scatter complex amplitude can be Fourier Transformed to obtain the Rayleigh scatter optical spectrum and shifts in the spectral pattern can related to changes in strain or temperature. Â This technique results in distributed strain measurements with 1 me resolution or temperature measurements with 0.1 C resolution. Â These measurements can be made with sub-cm spatial resolution over a 100 m measurement range or with sub-10 cm resolution over a 1 Km range. Â A principle advantage of this technique is that it does not require specialty fiber. Thus, measurements can be made in pre-installed single mode or multimode fibers, including those used for telecommunication networks. Â Applications range from fault monitoring in short range communications networks, structural health monitoring, shape sensing, pipeline and electrical transmission line monitoring, to perimeter security. Â Several examples are discussed in detail.
Citation
D. K. Gifford et al., "Swept-wavelength Interferometric Interrogation of Fiber Rayleigh Scatter for Distributed Sensing Applications," Optics East, Boston, MA, 2007 pp. 67700F-67700F.
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