-
公开(公告)号：US11994376B2
公开(公告)日：2024-05-28
申请号：US17634435
申请日：2020-02-13
Applicant: Nippon Telegraph and Telephone Corporation
Inventor： Tatsuya Okamoto , Daisuke Iida , Hiroyuki Oshida
IPC: G01B11/16
CPC classification number: G01B11/16
Abstract: The present disclosure provides a device that accurately measures vibration at a designated position of a sensing fiber without using digital signal processing to compensate for distance fluctuation. Digital signal processing for correcting fluctuation of a measurement distance due to a frequency offset of a beat signal due to vibration, which is a measurement target, is simplified. In the present disclosure, vibration at a designated position of the sensing fiber is accurately measured without using the digital signal processing to compensate for the distance fluctuation. A spectrum analysis length of an electrical field E(τn) of backscattered light is set to be larger than a delay deviation Nd due to frequency modulation caused by dynamic strain. An index of tolerance of vibration distribution measurement to the delay deviation Nd is also clarified.
-
公开(公告)号：US11920974B2
公开(公告)日：2024-03-05
申请号：US15734115
申请日：2019-05-23
Applicant: Nippon Telegraph and Telephone Corporation
Inventor： Tatsuya Okamoto , Daisuke Iida , Kunihiro Toge , Tetsuya Manabe
Abstract: A vibration distribution measurement system includes a frequency sweep light source that outputs frequency sweep light, an optical splitter that splits the frequency sweep light into probe light and local light, an optical mixer that mixes backscattered light from the sensing fiber as signal light with the local light, the backscattered light being obtained by causing the probe light to be incident on the sensing fiber, and an analysis unit that analyzes a beat signal obtained from output light of the optical mixer. The analysis unit estimates a distance offset from a measurement result obtained by measuring a distribution waveform of the signal light by measuring the beat signal at a measurement time sufficiently shorter than a cycle of the vibration of the sensing fiber, and measures a distribution of a vibration at any position by compensating for the distance offset.
-
公开(公告)号：US20210215532A1
公开(公告)日：2021-07-15
申请号：US15734115
申请日：2019-05-23
Applicant: Nippon Telegraph and Telephone Corporation
Inventor： Tatsuya Okamoto , Daisuke Iida , Kunihiro Toge , Tetsuya Manabe
Abstract: A vibration distribution measurement system includes a frequency sweep light source that outputs frequency sweep light, an optical splitter that splits the frequency sweep light into probe light and local light, an optical mixer that mixes backscattered light from the sensing fiber as signal light with the local light, the backscattered light being obtained by causing the probe light to be incident on the sensing fiber, and an analysis unit that analyzes a beat signal obtained from output light of the optical mixer. The analysis unit estimates a distance offset from a measurement result obtained by measuring a distribution waveform of the signal light by measuring the beat signal at a measurement time sufficiently shorter than a cycle of the vibration of the sensing fiber, and measures a distribution of a vibration at any position by compensating for the distance offset.
-
公开(公告)号：US11906387B2
公开(公告)日：2024-02-20
申请号：US17636930
申请日：2019-09-10
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Atsushi Nakamura , Daisuke Iida , Hiroyuki Oshida
Abstract: The purpose of the present disclosure is to provide a mode field diameter test method and test device that enable acquisition of a mode field diameter for an arbitrary higher-order mode. The present disclosure is a mode field diameter test method including: a test light incidence procedure for selectively causing test light to be incident in a mode subject to measurement, on one end of an optical fiber 10 under test; a far-field pattern measurement procedure for measuring a far-field pattern of the mode subject to measurement, with respect to a divergence angle θ at the other end of the optical fiber under test, by a far-field scanning technique; and a mode field diameter calculation procedure for calculating, using an equation, a mode field diameter from information about incident mode orders in the test light incidence procedure and the far-field pattern measured in the far-field pattern measurement procedure.
-
公开(公告)号：US11879803B2
公开(公告)日：2024-01-23
申请号：US17926655
申请日：2020-06-03
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Tomokazu Oda , Hiroyuki Oshida , Daisuke Iida , Atsushi Nakamura , Yuto Sagae
IPC: G01M11/00
CPC classification number: G01M11/39
Abstract: An optical fiber testing method is presented for measuring the change amount for the wave number k of a Brillouin Frequency Shift ν in stimulated Brillouin scattering generated in the same acoustic mode with respect to each target propagation mode. In this way, the ratio of the change amount measured at each propagation mode is acquired as the group delay ratio between the modes.
-
Patent Agency Ranking
6.发明授权公开(公告)号：US11788928B2
公开(公告)日：2023-10-17
申请号：US17622977
申请日：2019-07-11
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Tomokazu Oda , Yoshifumi Wakisaka , Daisuke Iida , Hiroyuki Oshida
IPC: G01M11/00 , G01M11/02 , H04B10/073
CPC classification number: G01M11/0285 , G01M11/39 , H04B10/073
Abstract: A light intensity distribution measurement apparatus is presented that is capable of accurately measuring the intensity of light in each mode at each position of an optical fiber through which light is propagated in a plurality of modes. With the light intensity distribution measurement apparatus, a gain coefficient matrix is acquired in advance, which is constituted by Brillouin gain coefficients of propagation modes with predetermined optical frequency differences measured using a reference optical fiber that exhibits the same properties as a measurement-target optical fiber and that does not cause mode coupling, and the intensity distribution of light in each propagation mode in a lengthwise direction of the measurement-target optical fiber is calculated based on the gain coefficient matrix and a difference in light intensity before and after Brillouin amplification of the probe light emitted in a predetermined propagation mode at a predetermined optical frequency difference measured using the measurement-target optical fiber.
-
公开(公告)号：US11754465B2
公开(公告)日：2023-09-12
申请号：US17426631
申请日：2019-09-04
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Atsushi Nakamura , Nazuki Honda , Daisuke Iida , Hiroyuki Oshida , Keiji Okamoto
IPC: G01M11/00
CPC classification number: G01M11/3127 , G01M11/3145 , G01M11/3154
Abstract: An object of the present invention is to provide an optical pulse test apparatus and an optical pulse test method that are capable of determining a change in state of an optical fiber connection portion without the need for reference and without being affected by changes in gap interval before and after the change in state. The optical pulse test apparatus according to the present invention is configured to perform an OTDR measurement by using test optical pulses having spectral widths of from several nm to several hundred nm arranged at intervals of several ten nm to several hundred nm, calculate a reflection peak value caused by the Fresnel reflection at the connection portion from the obtained OTDR waveform, and determine a state such as water immersion of the optical fiber connection portion based on the value.
-
公开(公告)号：US12298159B2
公开(公告)日：2025-05-13
申请号：US18283498
申请日：2021-03-25
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Tatsuya Okamoto , Daisuke Iida , Yusuke Koshikiya , Nazuki Honda
Abstract: The present disclosure generates an optical spectrogram, representing a temporal change in frequency characteristics, using a plurality of spectral data measured by an OFDR measurement instrument at different times, and filters the optical spectrogram in both a time direction and a frequency direction.
-
公开(公告)号：US11965758B2
公开(公告)日：2024-04-23
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：US11719599B2
公开(公告)日：2023-08-08
申请号：US17762185
申请日：2019-10-10
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Atsushi Nakamura , Tomokazu Oda , Daisuke Iida , Hiroyuki Oshida , Yoshifumi Wakisaka
IPC: G01M11/00
CPC classification number: G01M11/39
Abstract: This disclosure describes inputting pulsated pump light in a fundamental mode or a first higher-order mode into one end of an optical fiber under test constructed by connecting two optical fibers in series; inputting probe light having an optical frequency difference within a Brillouin frequency shift range with respect to the pump light into the other end of the optical fiber under test in the fundamental mode or the first higher-order mode; measuring a Brillouin gain distribution related to a distance of transmitted light intensity of probe light output from the one end into which the pump light was input; and calculating each inter-modal coupling efficiency at the connection point of the optical fiber under test.
-
-
-
-
-
-
-
-
-
Search Results
23
records
(took 0.018 seconds)
