Abstract
We analyze the source of the position deviation and propose a demodulation recursive compensation algorithm to ensure a sub-millimeter resolution in improved optical frequency domain reflectometry. The position deviation between the geometric path and optical path changes with the temperature or strain, due to the elastic-optic and thermal-optic effects. It accumulates along the fiber and becomes large enough to affect the spectral correlation between the measured and reference spectra at the fiber end. The proposed algorithm compensates for the position deviation of each measuring point and aligns the measured spectra with its reference. The numerical and experimental results both reveal that the signal-to-noise ratio of the correlation is improved doubly and a sub-millimeter spatial resolution becomes available at a 30 m fiber end. The recursive compensation algorithm helps to restrain the correlation degeneration at the fiber end and promises an effective approach to a sub-millimeter resolution in optical frequency domain reflectometry.
Highlights
Optical frequency domain reflectometry (OFDR), as a promising technique based on intrinsicRayleigh scattering (RS), was firstly introduced by W
OFDR was mainly used for loss and breakpoint diagnosis in optical fiber devices and networks [2,3]
With the development of the narrow linewidth tunable laser source (TLS) and nonlinear phase noise compensation in OFDR, the sensing range can be promoted to dozens of kilometers [6,7,8,9]
Summary
Optical frequency domain reflectometry (OFDR), as a promising technique based on intrinsic. PEER REVIEW spectrum registration to restrain the similarity degeneration of RS spectra and ensure a high spatial [15,16].using They resolution, the narrowsignificantly box window to extract a localspectral spectrum in the case ratio of a large obtained a micro-strain distribution curve along a m sensing fiber with a mm long fiberof the range. Distributed 7000 micro-strain along a 1.2 m sensing fiber is demodulated over a 5 mm of RS spectra and ensure a high spatial resolution, using the narrow box window to extract a local spatial resolution accurately This team proposed a demodulation approach based on spectrum in the case of a large measurable range. 0.5 mm over a m long sensing proposed a demodulation approach based on image processing to remove the noise caused by datagauge acquired and realize accurate measurements This technology verified at the spatial resolution by the compensation algorithm for position deviation. Experimental verification demonstrates that this proposed technique can satisfy the requirements of high-precision distributed sensing
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