Post-processing method to extend the functional range of optical backscatter reflectometry in extreme environments

A system comprising:

• a data processing apparatus communicatively coupled with an optical frequency domain reflectometry (OFDR) system that is configured to determine a spectrum of light that had been launched into an optical fiber from a tunable laser source and then backscattered by refractive index variations within a segment of the optical fiber, wherein the optical fiber is disposed in an environment that comprises neutron irradiation or temperatures of at least 750° C.;
• and
• memory communicatively coupled with the data processing apparatus, the memory encoding instructions that, when executed by the data processing apparatus, cause the system to perform operations comprising:
• receiving, from the OFDR system, a respective timed sequence of backscattered-light spectra associated with each segment of the optical fiber;
• and
• determining, for each optical-fiber segment, a set of values of a temperature or a strain of the optical-fiber segment corresponding to the received timed sequence of the backscattered-light spectra by performing operations comprising:
• selecting, for each backscattered-light spectrum of the timed sequence, a reference spectrum from among two or more earlier backscattered-light spectra of the timed sequence by determining, in reverse chronological order, a quality value based on a pairing of the backscattered-light spectrum and one of the earlier backscattered-light spectra, the selected reference spectrum corresponding to the first quality value determined to meet or exceed a predetermined threshold, the earlier backscattered-light spectra comprising all earlier backscattered-light spectra of the timed sequence,
• determining a spectral shift between the backscattered-light spectrum and the reference spectrum, and
• determining a value of the temperature or the strain of the optical-fiber segment based on the spectral shift.

A system comprising:

• a data processing apparatus communicatively coupled with an optical frequency domain reflectometry (OFDR) system that is configured to determine a spectrum of light that had been launched into an optical fiber from a tunable laser source and then backscattered by refractive index variations within a segment of the optical fiber, wherein the optical fiber is disposed in an environment that comprises neutron irradiation or temperatures of at least 750° C.;
• and
• memory communicatively coupled with the data processing apparatus, the memory encoding instructions that, when executed by the data processing apparatus, cause the system to perform operations comprising:
• receiving, from the OFDR system, a respective timed sequence of backscattered-light spectra associated with each segment of the optical fiber;
• and
• determining, for each optical-fiber segment, a set of values of a temperature or a strain of the optical-fiber segment corresponding to the received timed sequence of the backscattered-light spectra by performing operations comprising:
• selecting, for each backscattered-light spectrum of the timed sequence, a reference spectrum from among two or more earlier backscattered-light spectra of the timed sequence by determining a quality value based on a pairing of the backscattered-light spectrum and one of the earlier backscattered-light spectra, the selected reference spectrum having a highest quality value from among the determined quality values, the earlier backscattered-light spectra comprising all earlier backscattered-light spectra of the timed sequence,
• determining a spectral shift between the backscattered-light spectrum and the reference spectrum, and
• determining a value of the temperature or the strain of the optical-fiber segment based on the spectral shift.