公开(公告)号：US12078527B2

公开(公告)日：2024-09-03

申请号：US17630408

申请日：2020-01-22

Applicant: TIANJIN UNIVERSITY

Inventor： Junfeng Jiang ,  Tiegen Liu ,  Zhe Ma ,  Shuang Wang ,  Kun Liu ,  Zhenyang Ding ,  Xuezhi Zhang ,  Wenjie Chen ,  Guanhua Liang

IPC: G01H9/00 ,  G01D5/353 ,  G01H1/00 ,  G01N29/24

CPC classification number: G01H9/004 ,  G01D5/35329 ,  G01D5/35361 ,  G01H1/006 ,  G01H9/00 ,  G01N29/2418 ,  G01N2291/0423

Abstract: The present invention discloses a differential COTDR distributed acoustic sensing device based on heterogeneous double-sideband chirped-pulses of the invention, comprising a light source (1), a 1×2 polarization-maintaining optical-fiber coupler (2), a dual Mach-Zehnder electro-optical modulator (3), an arbitrary waveform generator (4), a first low noise microwave amplifier (5), a second low noise microwave amplifier (6), an electro-optical modulator bias control panel (7), a 1×2 optical-fiber coupler (8), an erbium-doped optical-fiber amplifier (9), an optical-fiber filter (10), an optical-fiber circulator (11), a sensing optical fiber (12), a tricyclic polarization controller (13), a 2×2 optical-fiber coupler (14), a balanced photoelectric detector (15), a data acquisition card (16) and a processing unit (17). The present invention combines heterogeneous double-sideband chirped-pulse modulation and coherent light time-domain reflection technology, so as to double the sensitivity of the to-be-measured acoustic wave signal and to suppress common-mode noise, and further improves SNR.

公开(公告)号：US11473992B2

公开(公告)日：2022-10-18

申请号：US16641738

申请日：2018-04-23

Applicant: TIANJIN UNIVERSITY

Inventor： Shuang Wang ,  Junfeng Jiang ,  Tiegen Liu ,  Xue Wang ,  Kun Liu ,  Mengnan Xiao ,  Dongdong Ju

IPC: G01L27/00 ,  G01L11/02 ,  G01L19/04

Abstract: The present invention discloses a residual pressure measurement system for a MEMS pressure sensor with an F-P cavity and method thereof, the measurement system includes a low-coherence light source, a 3 dB coupler, a MEMS pressure sensor, an air pressure chamber, a thermostat, a pressure control system, a cavity length demodulator, an acquisition card and a computer. The measurement method comprises: performing cavity length measurement by using the reflecting light by the pressure control system at two temperatures, respectively, so as to calibrate the MEMS pressure sensor and establish a relationship between the absolute phase of a monochromatic frequency and the external pressure; performing linear fitting to the two measurement data to obtain all the external pressure when the cavity length of two measurement data are equal to each other, and substituting the theoretical equation for calculation to obtain the residual pressure under the flat condition of the diaphragm.

公开(公告)号：US11181400B2

公开(公告)日：2021-11-23

申请号：US16324275

申请日：2016-10-27

Applicant: Tianjin University

Inventor： Junfeng Jiang ,  Tiegen Liu ,  Jinling Yan ,  Kun Liu ,  Shuang Wang ,  Xuezhi Zhang ,  Chuanjun Zang ,  Renwei Xie ,  Qiliang Chu

IPC: G01D5/353 ,  G01D3/028 ,  G01D18/00

Abstract: The present invention discloses a Fiber Bragg Grating demodulation device with a suppressed fluctuation at a variable ambient temperature and a demodulation method. The device comprises a broadband light source (1), an optical attenuator (2), a tunable F-P filter (3), a first optical fiber isolator (41), an erbium-doped optical fiber amplifier (5), an optical fiber first-stage beam splitter (6), a first optical fiber second-stage beam splitter (71), optical fiber circulators (8), FBG sensor arrays (9), a first photoelectric detector array (161), an optical fiber gas cell (10), a second optical fiber second-stage beam splitter (72), an optical fiber F-P etalon (11), a notch filter (12), an optical fiber assisted interferometer (13), a data acquisition card (17) and a processor (18).

公开(公告)号：US10508938B2

公开(公告)日：2019-12-17

申请号：US15559429

申请日：2016-10-27

Applicant: Tianjin University

Inventor： Tiegen Liu ,  Junfeng Jiang ,  Huijia Yang ,  Kun Liu ,  Shuang Wang ,  Weihang Zhang

IPC: G01F1/66 ,  G01F1/38

Abstract: Fiber optical Fabry-Perot flow test device with local bending diversion structure, having an inlet flange, a test tube and an outlet flange, with both a fiber optical Fabry-Perot pressure sensor at high-pressure-side and a fiber optical Fabry-Perot pressure sensor at low-pressure-side, which are fixedly connected to the test tube through an auxiliary connecting device.

公开(公告)号：US10365126B2

公开(公告)日：2019-07-30

申请号：US15567076

申请日：2016-10-27

Applicant: Tianjin University

Inventor： Kun Liu ,  Tiegen Liu ,  Junfeng Jiang ,  Chunyu Ma ,  Tianjiao Chai ,  Chang He ,  Miao Tian ,  Zhichen Li

IPC: G01D5/353 ,  G08B13/186 ,  G01H9/00

Abstract: A distributed optical fiber disturbance positioning system based on the asymmetric dual Mach-Zehnder interference, unlike traditional dual Mach-Zehnder distributed optical fiber disturbance sensing system, the present invention adopts two narrow-bandwidth optical sources (1a, 1b) and adopts corresponding DWDM (3a, 3b) before the detector (4a, 4b) to filter the backscatter noise of the optical fiber, and can solve the problems of having too low SNR due to backscatter influence when the sensing distance is long. The present invention also provides a positioning method for applying the system, which obtains the TFD of the disturbance frame signals by using the time-frequency analysis method based on the short-term average frequency, and takes the points near the point of maximum frequency as the effective signal segment for performing cross-correlation time delay estimation, thus obtaining the delay, and the disturbance position. The method of the invention positions the asymmetric disturbance frame signals in the systems, thus having a high positioning accuracy and reliability.

公开(公告)号：US10365088B2

公开(公告)日：2019-07-30

申请号：US15567078

申请日：2016-10-27

Applicant: Tianjin University

Inventor： Zhenyang Ding ,  Di Yang ,  Tiegen Liu ,  Yang Du ,  Zhexi Xu ,  Kun Liu ,  Junfeng Jiang

IPC: G01B11/16 ,  G01D5/353 ,  G02B6/293

Abstract: The present invention discloses a distributed device for simultaneously measuring strain and temperature based on optical frequency domain reflection, comprising a tunable laser, a 1:99 beam splitter, a main interferometer system, a light source phase monitoring system based on an auxiliary interferometer, an acquisition device and a computer processing unit, wherein the main interferometer system comprises two Mach-Zehnder interferometers, and two optical fibers having different cladding diameters are arranged in parallel as sensing fibers. Due to the difference in temperature and strain coefficients of optical fibers of the same diameter, the temperature and strain values during changing the temperature and strain simultaneously can be obtained by matrix operation, thereby achieving an effect of eliminating cross sensitivity of temperature and strain sensing in optical frequency domain reflection.