# US 12,761,052 B2 · Sensing system, sensing method, and analyzer

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- Number: US 12,761,052 B2
- Document ID: US12761052B2
- Status: Granted
- Kind: B2
- Application number: 18/682,212
- Filed: 2021-08-16
- Published: 2024-08-15
- Granted: 2026-10-13
- Earliest claimed: 2021-08-16
- Assignees: NTT, Inc.
- Applicants: NTT, Inc.
- Inventors: Tatsuya Okamoto; Daisuke Iida; Yusuke Koshikiya; Nazuki Honda
- Web page: https://patentgrep.com/patent/US12761052B2

## CPC

- G01D 5/35361: {using elastic backscattering to detect the measured quantity, e.g. using Rayleigh backscattering}
- G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR

## Abstract

An object of the present invention is to provide a sensing system, a sensing method, and an analyzing device using OFDR in which a sensing range of strain/temperature is less likely to be limited by a frequency sweep width. In the sensing method using OFDR, the sensing system according to the present invention employs sequential update, per measurement by one frequency sweep of the probe light, for setting the reference spectrum to the spectrum of an immediately preceding measurement, by which a spectral shift between an n-th measurement and an (n−1)th measurement is obtained, and the spectral shifts individually obtained between the measurements are integrated.

## Claims

### Claim 1

A sensing system that includes a measuring device and an analyzing device, wherein
the measuring device is configured to input a probe light whose frequency is swept once over a frequency sweep width ΔF into an optical fiber, and repeatedly perform measurement using Optical Frequency Domain Reflectometry (OFDR) for acquiring a spectrum of a backscattered light, and
the analyzing device is configured to:
calculate an individual spectral shift that is an amount of change in the spectrum obtained in a current measurement, using a portion of the spectrum obtained in an immediately preceding measurement that falls within the frequency sweep width ΔF as a reference spectrum, and
integrate the individual spectral shift for each measurement up to the current measurement to give the spectral shift at a time of the current measurement.

### Claim 2

A sensing method comprising:
inputting a probe light whose frequency is swept once over a frequency sweep width ΔF into an optical fiber, and repeatedly performing measurement using Optical Frequency Domain Reflectometry (OFDR) for acquiring spectrum of a backscattered light;
calculating an individual spectral shift that is an amount of change in the spectrum obtained in a current measurement, using a portion of the spectrum obtained in an immediately preceding measurement that falls within the frequency sweep width ΔF as a reference spectrum; and
integrating the individual spectral shift for each measurement up to the current measurement to give the spectral shift at a time of the current measurement.

### Claim 3

An analyzing device for analyzing spectrum obtained in measurement which a measuring device inputs a probe light whose frequency is swept once over a frequency sweep width ΔF into an optical fiber, and repeatedly performs measurement using Optical Frequency Domain Reflectometry (OFDR) for acquiring the spectrum of a backscattered light, the analyzing device configured to:
calculate an individual spectral shift that is an amount of change in the spectrum obtained in a current measurement, using a portion of the spectrum obtained in an immediately preceding measurement that falls within the frequency sweep width ΔF as a reference spectrum, and
integrate the individual spectral shift for each measurement up to the current measurement to give the spectral shift at a time of the current measurement.