公开(公告)号：US20230358599A1

公开(公告)日：2023-11-09

申请号：US18025683

申请日：2020-09-11

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Yoshifumi WAKISAKA ,  Daisuke IIDA ,  Tatsuya OKAMOTO ,  Nazuki HONDA ,  Hiroyuki OSHIDA

IPC: G01H9/00

CPC classification number: G01H9/004

Abstract: An object is to provide a vibration detection apparatus and a vibration detection method which can avoid occurrence of a point where detection sensitivity deteriorates in vibration detection of a scattered light intensity monitor according to optical frequency multiplexing.
The present invention conceives a multi-dimensional space having as many dimensions as the number of frequencies to be used, causes scattered light intensity change at each optical frequency to correspond to each axis, plots a scattered light signal as a vector on the space, performs linear approximation passing through an origin on the space having a plurality of plotted vector points as original data, and performs vibration detection using a direction vector of an approximate straight line obtained as a result of the approximation.

公开(公告)号：US20230332980A1

公开(公告)日：2023-10-19

申请号：US18026856

申请日：2020-10-07

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Tomokazu ODA ,  Atsushi NAKAMURA ,  Daisuke IIDA ,  Yusuke KOSHIKIYA ,  Nazuki HONDA

IPC: G01M11/02

CPC classification number: G01M11/02

Abstract: An object of the present invention is to provide an optical fiber measurement system, an optical fiber measurement method, a control calculation device, and a program that are capable of measuring loss and XT occurring at a plurality of points of an optical fiber in which a plurality of modes propagate, for each point. An optical fiber measurement system according to the present invention includes a light incident circuit which makes a probe light incident on one end of an optical fiber and makes a secondary probe light and a pump light as an optical pulse incident on the other end of the optical fiber; a light receiver which measures a light intensity of arbitrary one propagation mode in the probe light propagating through the optical fiber; and a control calculation device which sets a propagation mode of the probe light, the secondary probe light, and the pump light, an optical frequency difference of the secondary probe light, and an optical frequency difference of the pump light with respect to the light incident circuit, and calculates loss and crosstalk at each point in a longitudinal direction of the optical fiber to be measured connected as the optical fiber, from the light intensity measured by the light receiver.

公开(公告)号：US20230288289A1

公开(公告)日：2023-09-14

申请号：US18020982

申请日：2020-08-21

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Atsushi NAKAMURA ,  Tomokazu ODA ,  Daisuke IIDA ,  Hiroyuki OSHIDA

IPC: G01M11/00 ,  G01M11/02

CPC classification number: G01M11/332 ,  G01M11/0207

Abstract: An object of the present disclosure is to provide a few-mode fiber testing method and a few-mode fiber testing device capable of acquiring a loss and inter-mode crosstalk for each mode at a connection point of a few-mode fiber by measurement only from one end of FUT. The few-mode fiber testing method according to the present disclosure includes receiving a test light pulse in a basic mode from one end of an optical fiber under test that is connected in series with few-mode fibers of the same type, measuring an intensity distribution relating to a distance from the one end of backward Brillouin scattering light generated by receiving a test light pulse, obtaining a transmittance of the backward Brillouin scattering light at a connection point of the optical fiber under test from the measured intensity distribution, and calculating a connection loss of the basic mode from the transmittance, calculating a ratio of an axial deviation amount to a mode field radius of the optical fiber under test at the connection point from the calculated connection loss, and calculating a connection loss of a higher-order mode and inter-mode crosstalk between different modes from the calculated ratio.

公开(公告)号：US20230236044A1

公开(公告)日：2023-07-27

申请号：US17923263

申请日：2020-05-21

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Atsushi NAKAMURA ,  Chihiro KITO ,  Daisuke IIDA ,  Junichi KAWATAKA ,  Hiroyuki OSHIDA

IPC: G01D5/353

CPC classification number: G01D5/35364

Abstract: An object of the present invention is to provide a Brillouin optical sensing device and an optical sensing method capable of reducing introduction costs. The Brillouin optical sensing device according to the present invention includes: a sensing fiber 90 in which a plurality of optical fibers having Brillouin frequency shift characteristics different from each other are arranged in parallel; an optical measuring instrument 11 that launches an optical pulse into at least two of the optical fibers of the sensing fiber 90 to generate Brillouin scattering lights and measures a beat frequency of a beat signal between the Brillouin scattering lights at any position of the sensing fiber 90; and an arithmetic processing unit 12 that acquires a physical quantity of the sensing fiber 90 at said any position based on the beat frequency acquired by the optical measuring instrument 11.

公开(公告)号：US20220155139A1

公开(公告)日：2022-05-19

申请号：US17440514

申请日：2020-03-19

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Yoshifumi WAKISAKA ,  Daisuke IIDA ,  Kunihiro TOGE ,  Hiroyuki OSHIDA

IPC: G01H9/00 ,  G01D5/353

Abstract: It is intended to provide a phase measurement method and a signal processing device that are capable of reducing influence of noise of a measuring device without increasing the peak intensity of an incident light pulse when measuring the phase of scattered light in DAS-P.
A phase measurement method according to the present invention causes wavelength-multiplexed pulse light to be incident on a measurement target optical fiber, produces a scattered light vector obtained by plotting scattered light from the measurement target optical fiber for each wavelength onto a two-dimensional plane having the in-phase component thereof on the horizontal axis and the orthogonal component thereof on the vertical axis, rotates the produced scattered light vector for each wavelength at each place in the measurement target optical fiber to align the directions of the vectors, generates a new vector by calculating the arithmetic average of the vectors having the aligned directions, and calculates the phase by using the values of the in-phase and orthogonal components of the generated new vector.

公开(公告)号：US20250123415A1

公开(公告)日：2025-04-17

申请号：US18682522

申请日：2021-08-16

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Tatsuya OKAMOTO ,  Daisuke IIDA ,  Yusuke KOSHIKIYA ,  Nazuki HONDA

IPC: G01V1/01 ,  G01H9/00 ,  G01V1/22

Abstract: The present disclosure provides an underground facility position contrast system S, which includes: a scattered light intensity distribution measurement device 1 for measuring, when an earthquake vibration is applied to an optical fiber F laid underground, a change over time in a scattered light intensity distribution in a longitudinal direction of the optical fiber F; and an underground facility position contrast device 2 for measuring a change over time in a distortion response distribution in the longitudinal direction of the optical fiber F based on the change over time in the scattered light intensity distribution in the longitudinal direction of the optical fiber F, estimating an underground facility state of the optical fiber F based on the change over time in the distortion response distribution in the longitudinal direction of the optical fiber F, and associating the underground facility position of the optical fiber F with a longitudinal distance of the optical fiber F.

公开(公告)号：US20240118126A1

公开(公告)日：2024-04-11

申请号：US18275726

申请日：2021-02-17

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Tatsuya OKAMOTO ,  Daisuke IIDA ,  Yusuke KOSHIKIYA ,  Nazuki HONDA

IPC: G01H9/00 ,  G01D5/353

CPC classification number: G01H9/004 ,  G01D5/35358

Abstract: An object of the present disclosure is to provide a method for remotely identifying a utility pole position and estimating a state of an overhead optical fiber cable.
The present disclosure is a method for identifying a utility pole position including identifying a boundary region of a vibration distribution as a utility pole position, from a vibration distribution pattern obtained by measuring strain amounts with respect to distances of an optical fiber by an optical fiber vibration distribution measuring method at each time and sequentially stacking the strain amounts.

公开(公告)号：US20230341245A1

公开(公告)日：2023-10-26

申请号：US18025697

申请日：2020-09-15

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Tatsuya OKAMOTO ,  Daisuke IIDA ,  Hiroyuki OSHIDA

IPC: G01D5/353

CPC classification number: G01D5/35358

Abstract: The present disclosure aims to enable measurement of a long distance exceeding 1 km with a spatial resolution of 100 μm or lower, and diagnosis of health of an optical device installed at a long distance.
An apparatus according to the present disclosure is an optical frequency domain reflectivity measuring apparatus that includes: a local light delay fiber that delays local light; an optical 90-degree hybrid that receives an input of the local light delayed by the local light delay fiber and backscattered light from the measurement target, causes the local light and the backscattered light to interfere with each other, and generates an in-phase component and an orthogonal component of a beat signal generated by the interference; and a balance photodetector that detects the in-phase component and the orthogonal component of the beat signal. In the apparatus, an optical frequency response of the measurement target is measured with respect to a relative distance based on the local light delay fiber.

公开(公告)号：US20230288231A1

公开(公告)日：2023-09-14

申请号：US18020969

申请日：2020-08-26

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Tatsuya OKAMOTO ,  Daisuke IIDA ,  Hiroyuki OSHIDA

IPC: G01D5/353 ,  G01H9/00

CPC classification number: G01D5/35361 ,  G01H9/004

Abstract: An object of the present disclosure is to enable vibration analysis using a spectral shift under appropriate conditions depending on a measurement object.
According to the present disclosure, there is provided a vibration distribution measuring apparatus which measures backscattered light in an optical fiber to be measured a plurality of times at different times, extracts an optical spectrum of a window section determined from a plurality of backscattered light waveforms obtained by the measurement, and measures a vibration distribution in the optical fiber to be measured using optical spectra of the plurality of extracted backscattered light waveforms, in which the optical spectrum of the window section is calculated using the window section in which the vibration amplitude in the window section in the optical fiber to be measured is larger than a threshold value defined in the window section.

公开(公告)号：US20220364846A1

公开(公告)日：2022-11-17

申请号：US17636941

申请日：2019-09-03

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Daisuke IIDA ,  Keiji OKAMOTO ,  Hiroyuki OSHIDA

IPC: G01B11/16

Abstract: The present invention intends to provide an optical fiber cable sensing apparatus capable of measuring longitudinal directional distribution of curvature and torsion, without using a specially structured optical fiber sensor. This apparatus includes means for inputting data of longitudinal directional distribution of distortion (bending loss, polarization variation) measured for each optical fiber accommodated in an optical fiber cable to be measured and data indicating the position of each measurement object optical fiber on a cable cross section, means for calculating curvature vector κ of the optical fiber cable to be measured, at the same spot, based on the distortion (bending loss, polarization variation) of each optical fiber at the spot and the position of the optical fiber on the cable cross section, and means for calculating torsion τ of the optical fiber cable to be measured at the spot from the calculated curvature vector κ.