Patent ID: 9689752
Date: 2017-06-27
CPC Classifications: G01B,G01D,G01K,G01M

Claim:
1. An OFDR device that measures a strain distribution or a temperature distribution of a measured optical fiber, the device comprising: a light source that outputs wavelength-swept light; a measured optical fiber that includes a fiber Bragg grating unit; an optical splitter/combiner that inputs part of output light from the light source to the measured optical fiber and combines reflected light from the measured optical fiber and part of output light from the light source; an optical receiver that converts light from the optical splitter/combiner into an electrical signal; an A/D converter that converts the electrical signal into a digital signal; a spectrogram calculator that calculates a spectrogram by performing discrete Fourier transform on the digital signal; and a peak wavelength detector that detects one or more peak wavelengths of the spectrogram on a wavelength axis, wherein the fiber Bragg grating unit includes a plurality of gratings that is overlappingly formed in order to reflect a plurality of different wavelengths, the OFDR device further includes a measuring range non-inclusion detector that detects gratings of the plurality of gratings of which the reflected wavelengths are not included in a predetermined measured wavelength range from the peak wavelengths detected by the peak wavelength detector based on measured wavelength range non-inclusion detecting condition data (Ds) which have the measured wavelength range toward the wavelength axis of the peak wavelengths, and a strain or temperature detector that measures a strain distribution or a temperature distribution of the measured optical fiber based on results from the measuring range non-inclusion detector and the peak wavelengths detected by the peak wavelength detector.