| CPC G01D 5/35316 (2013.01) [G02B 6/02085 (2013.01)] | 20 Claims |
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1. A strain measurement system comprising:
an optical fiber comprising a fiber core including overlapping first and second sets of gratings, the first and second overlapping sets of gratings having chirp rates that differ in direction or in magnitude or in both direction and magnitude;
interrogation means for coupling light into the fiber core and measuring a time-domain reflection signal resulting from reflections of the light off the overlapping first and second sets of gratings; and
computational processing means comprising:
conversion means for converting the measured time-domain reflection signal into a plurality of measurement reflection spectra associated with different time delays;
mapping means for mapping each measurement reflection spectrum of the plurality of measurement reflection spectra to a reference reflection spectrum of a plurality of reference reflection spectra and to an associated frequency shift between the measurement reflection spectrum and the reference reflection spectrum, whereby the associated frequency shift is associated with a unique location corresponding to the reference reflection spectrum; and
strain determination means for determining, based on the associated frequency shifts, strain in the fiber core along the optical fiber.
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