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：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：US20230085614A1

公开(公告)日：2023-03-16

申请号：US17798299

申请日：2020-02-13

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Kazutaka NOTO ,  Nazuki HONDA ,  Hiroyuki OSHIDA

IPC: G01N25/68 ,  G01K11/322

Abstract: An object of the present disclosure is to realize water immersion detection that does not require a replacement module, and does not cause any optical loss. The present disclosure relates to a device configured to measure guided acoustic wave Brillouin scattering in a measurement target optical fiber, and detect water immersion of the measurement target optical fiber based on a characteristic around a peak of the guided acoustic wave Brillouin scattering.

公开(公告)号：US20220215572A1

公开(公告)日：2022-07-07

申请号：US17608963

申请日：2019-05-08

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Hitoshi NIIGAKI ,  Yasuhiro YAO ,  Masaaki INOUE ,  Tomoya SHIMIZU ,  Yukihiro GOTO ,  Shigehiro MATSUDA ,  Ryuji HONDA ,  Hiroyuki OSHIDA ,  Kana KURATA ,  Shingo ANDO ,  Atsushi SAGATA

IPC: G06T7/70 ,  G06T7/00

Abstract: Provided is a point cloud analysis device that curbs a decrease in model estimation accuracy due to a laser measurement point cloud. A clustering unit (30) clusters a point cloud representing a three-dimensional point on an object obtained by a measurement unit mounted on a moving body and performing measurement while scanning a measurement position, within a scan line, to obtain a point cloud cluster. A central axis direction estimation unit (32) estimates a central axis direction based on the point cloud cluster. A direction-dependent local effective length estimation unit (34) estimates a local effective length based on an estimated central axis direction and an interval of scan lines, the local effective length being a length when a length of projection of the point cloud cluster in a central axis direction for each of the point cloud clusters is interpolated by an amount of a loss part of the point cloud.

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：US20210381926A1

公开(公告)日：2021-12-09

申请号：US17283597

申请日：2019-06-13

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Atsushi NAKAMURA ,  Keiji OKAMOTO ,  Hiroyuki OSHIDA

IPC: G01M11/00

Abstract: The present invention has an object to provide an optical fiber test method and an optical fiber test apparatus for measuring a mode dependent loss and an inter-modal crosstalk in a fundamental mode and a first higher-order mode at a connection point of a few-mode fiber. In the optical fiber test method and test apparatus according to the present invention, the mode dependent loss and the inter-modal crosstalk in the fundamental mode and the first higher-order mode at the connection point are calculated by using an approximation expression of an inter-modal coupling efficiency that is obtained in approximating electric field distributions of the fundamental mode and the first higher-order mode in a few-mode fiber by Gaussian function and Hermite Gaussian function.

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：US20230088679A1

公开(公告)日：2023-03-23

申请号：US17798535

申请日：2020-02-13

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Kazutaka NOTO ,  Nazuki HONDA ,  Hiroyuki OSHIDA

IPC: G01D5/353 ,  G01L1/24 ,  G01K11/322 ,  G01H9/00

Abstract: An object of the present disclosure is to detect a microbend in an optical fiber before the light-receiving intensity of a transmission device decreases. The present disclosure relates to a device configured to measure guided acoustic wave Brillouin scattering in a measurement target optical fiber, and detect a microbend in the measurement target optical fiber based on a characteristic around a peak of the guided acoustic wave Brillouin scattering.