CN115824378A - Vibration detection method of high-frequency-response distributed optical fiber acoustic wave sensor - Google Patents
Vibration detection method of high-frequency-response distributed optical fiber acoustic wave sensor Download PDFInfo
- Publication number
- CN115824378A CN115824378A CN202211227596.XA CN202211227596A CN115824378A CN 115824378 A CN115824378 A CN 115824378A CN 202211227596 A CN202211227596 A CN 202211227596A CN 115824378 A CN115824378 A CN 115824378A
- Authority
- CN
- China
- Prior art keywords
- frequency
- optical fiber
- light
- backward rayleigh
- acoustic wave
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Landscapes
- Length Measuring Devices By Optical Means (AREA)
Abstract
The invention provides a vibration detection method of a high-frequency response distributed optical fiber acoustic wave sensor, which comprises the following steps: step 1: the data acquisition card 7 acquires an electric signal; step 2: performing time-frequency analysis on the electric signal to obtain a beat frequency-optical frequency fingerprint graph of the backward Rayleigh scattering light of the sensing optical fiber 5; and step 3: detecting the translation amount of the backward Rayleigh scattering light at the position to be detected of the sensing optical fiber 5 in the beat frequency direction by adopting an image matching method, thereby obtaining the position of the backward Rayleigh scattering light at the position to be detected in the whole beat frequency-optical frequency fingerprint graph; and 4, step 4: and obtaining the instantaneous optical frequency shift corresponding to the position to be measured, thereby solving the strain magnitude of the sensing optical fiber 5 at the position to be measured. The invention effectively inhibits the crosstalk of the high-frequency vibration of the front section of the sensing optical fiber to the vibration detection of the rear section of the sensing optical fiber, improves the corresponding bandwidth of the sensing system and improves the distributed vibration measurement capability of the sensing system.
Description
Technical Field
The invention relates to the technical field of optical fiber sensing, in particular to a vibration detection method of a high-frequency-response distributed optical fiber acoustic wave sensor, and particularly relates to a vibration detection method of a high-frequency-response distributed optical fiber acoustic wave sensor capable of inhibiting crosstalk.
Background
Distributed Fiber-optic Acoustic Sensor (DAS) is increasingly used in important fields such as oil and gas resource exploration, oil and gas pipeline monitoring, and railway track monitoring. The DAS can use a common single-mode communication optical fiber as a sensor, each small section of the optical fiber can be regarded as a microphone capable of detecting an acoustic vibration signal in the environment, the position of the vibration signal can be accurately located, and more importantly, the waveform of the acoustic vibration signal can be quantitatively acquired for further analysis. Compared with the traditional acoustic wave sensor based on the mechanical or electromagnetic principle, the DAS has the advantages of a common optical fiber sensor, such as electromagnetic interference resistance, corrosion resistance, intrinsic passivity and the like, and has distributed measurement capability, large-scale acoustic wave sensor multiplexing is easy to realize, and the problems of power supply, signal transmission and the like in the traditional acoustic wave sensor multiplexing scheme are avoided. In the scenes of monitoring the structure of the aircraft body, monitoring the state of turbine blades, positioning a sound source in fluid and the like, a DAS system is required to have higher spatial resolution, the existing DAS technology is mostly based on an optical time domain reflectometer technology, the spatial resolution is more than one meter, and the DAS technology is difficult to be directly applied to the scenes.
The spatial resolution of a DAS system based on an Optical Frequency Domain Reflectometer (OFDR) or a Time-gated Optical Frequency Domain reflectometer (TGD-OFDR) is determined by the sweep range of the detection light, so that the spatial resolution and the duration of the detection light are decoupled, and the DAS system can have a very high spatial resolution. However, because the detection light duration of the scheme is long, when the optical fiber is vibrated, the phase modulation applied to the detection light by the vibration is no longer a fixed value within the detection light duration, so that the vibration causes crosstalk to strain demodulation of subsequent positions thereof, and even causes failure of a demodulation method, so that the current DAS system with high spatial resolution cannot correctly detect a high-frequency vibration signal, and the response bandwidth is severely limited.
Patent document CN113295257A discloses a method and a system for demodulating signals of an optical fiber acoustic wave sensor, which are different in that the method comprises the following steps: step 1: broadband light provided by a light source passes through the optical fiber acoustic wave sensor, and the broadband light interferes; step 2: screening the interfered broadband light to form N paths of narrow-band light with certain wavelength intervals; and step 3: obtaining corresponding N paths of interference light intensity by N paths of different wavelengths of the narrow-band light; converting the N paths of interference light intensity into N paths of corresponding voltage signals; and 4, step 4: carrying out multichannel sampling on the N voltage signals to sample N demodulation working point voltages; and 5: obtaining a path of signal with the best intensity demodulation effect as a demodulation signal; step 6: the demodulated signal is processed and restored to become an acoustic signal. The invention increases demodulation stability and reliability, and improves the batch practicability of the optical fiber acoustic wave sensor. However, the scheme is only suitable for solving the problem of the static working point drift of the sensor under the change of environmental factors, and cannot solve the problem of crosstalk caused by the vibration on the optical fiber to the strain demodulation of the subsequent position of the optical fiber.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a vibration detection method of a high-frequency-response distributed optical fiber acoustic wave sensor.
The vibration detection method of the high-frequency-response distributed optical fiber acoustic wave sensor comprises the high-frequency-response distributed optical fiber acoustic wave sensor, wherein the high-frequency-response distributed optical fiber acoustic wave sensor comprises a laser module, an optical fiber coupler, an optical fiber circulator, a sensing optical fiber, a coherent detection module, a data acquisition card and a data processor;
laser output by the laser module is divided into probe light and local light through an optical fiber coupler, the probe light forms backward Rayleigh scattered light after being input into a sensing optical fiber through an optical fiber circulator, the backward Rayleigh scattered light serves as signal light to be input into a coherent detection module through the optical fiber circulator, the local light is input into the coherent detection module, the coherent detection module can beat the backward Rayleigh scattered light and the local light to form electric signal output, the data acquisition card can acquire the electric signal, and the data processor can process the electric signal;
the detection light input into the optical fiber circulator is a sweep frequency light pulse string;
the vibration detection method of the high-frequency-response distributed optical fiber acoustic wave sensor further comprises the following steps of:
step 1: the data acquisition card acquires an electric signal;
and 2, step: time-frequency analysis is carried out on the electric signals to obtain a beat frequency-optical frequency domain fingerprint image of backward Rayleigh scattering light;
and step 3: detecting the translation amount of the backward Rayleigh scattered light at the position to be detected of the sensing optical fiber in the beat frequency-optical frequency domain fingerprint image by adopting an image matching method, thereby obtaining the position of the backward Rayleigh scattered light at the position to be detected in the whole beat frequency-optical frequency domain fingerprint image;
and 4, step 4: according to the position of the backward Rayleigh scattering light of the position to be measured in the whole beat frequency-optical frequency domain fingerprint image, the instantaneous optical frequency shift corresponding to the position to be measured is obtained, and therefore the strain of the position to be measured of the sensing optical fiber is obtained.
Preferably, in step 1, after the data acquisition card collects the electric signals, a time-frequency analysis method is adopted to form a two-dimensional array, and the two-dimensional array is marked according to the emission time sequence;
the time-frequency analysis method comprises short-time Fourier transform and wavelet transform.
Preferably, in step 2, after time-frequency analysis is performed on the electrical signal, a beat-light frequency domain fingerprint image of the backward rayleigh scattered light at each position of the sensing fiber during the nth detection is obtained.
Preferably, the step 3 comprises the steps of:
step 3.1: adopting an image matching method, wherein the image matching method comprises the following steps: taking a subregion corresponding to a certain position L to be detected of a sensing optical fiber on a beat-light frequency domain fingerprint image of backward Rayleigh scattering light obtained by the 1 st detection and at a certain time point t in time as a reference subregion, using image matching near the reference subregion on the beat-light frequency domain fingerprint image of the backward Rayleigh scattering light obtained by the nth detection to find the subregion to be detected which is most matched with the reference subregion, and obtaining the translation amount of the backward Rayleigh scattering light on the beat-light frequency domain fingerprint image corresponding to the time and the space at the position L to be detected of the sensing optical fiber;
step 3.2: and (3) repeating the step 3.1 by changing the time point t until the position of the backward Rayleigh scattering light corresponding to the position L to be measured on the space in the whole beat frequency-optical frequency domain fingerprint image is obtained.
Preferably, the step 4 comprises the steps of:
step 4.1: according to the position of the backward Rayleigh scattering light corresponding to the position L to be detected in the space in the whole beat frequency-light frequency domain fingerprint image obtained by the nth detection, obtaining the corresponding instantaneous light frequency shift of the position L to be detected;
step 4.2: and obtaining the frequency spectrum or phase change information of the backward Rayleigh scattering light corresponding to the position L to be detected, which is obtained by the nth detection, according to the instantaneous optical frequency shift, thereby obtaining the strain magnitude.
Preferably, the method further comprises the step 5: changing n and L, and repeating the steps 3-4 until the change of the strain distribution on the whole sensing optical fiber (5) along with time is obtained.
Preferably, in step 4.2, the frequency spectrum frequency shift Δ ν of the backward rayleigh scattering light at the position to be measured is obtained according to the corresponding instantaneous optical frequency shift at the position to be measured L, and the dependent variable is
Wherein, K ε-ν V is the strain-frequency shift coefficient 0 Is the center frequency.
Preferably, in step 4.2, the differential phase variation Δ Φ of the backward rayleigh scattered light at the position to be measured is obtained according to the corresponding instantaneous optical frequency shift at the position to be measured L, and the dependent variable is
Wherein, K ε-φ For the strain-phase coefficient, Δ L is the differential distance.
Preferably, the laser module adopts a swept-frequency laser, and the swept-frequency laser can output a swept-frequency optical pulse train.
Preferably, the laser module adopts a narrow linewidth laser, the high-frequency response distributed optical fiber acoustic wave sensor further includes a radio frequency signal module and an optical modulator, the optical modulator is arranged between the optical fiber coupler and the optical fiber circulator, the radio frequency signal module can input a sweep frequency radio frequency pulse string signal to the optical modulator, and the probe light can form a sweep frequency optical pulse string through the optical modulator.
Compared with the prior art, the invention has the following beneficial effects:
the invention effectively inhibits the crosstalk of the high-frequency vibration of the front section of the sensing optical fiber to the vibration detection of the rear section of the sensing optical fiber, improves the corresponding bandwidth of the sensing system and improves the distributed vibration measurement capability of the sensing system.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a schematic structural diagram of a high frequency response distributed fiber acoustic wave sensor according to the present invention;
FIG. 2 is a time-frequency analysis diagram of a swept-frequency optical pulse train in accordance with the present invention;
FIG. 3 is a beat frequency-optical frequency domain fingerprint image of the backward Rayleigh scattering light of the present invention;
FIG. 4 is a graph of the strain distribution near the vibration region of the present invention;
shown in the drawings
Frequency-swept laser 1 sensing optical fiber 5
Coherent detection module 6 of optical fiber coupler 2
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
The invention discloses a vibration detection method of a high-frequency response distributed optical fiber sound wave sensor, which can eliminate the distributed vibration of crosstalk of high-frequency vibration of an optical fiber front section to rear section optical fiber vibration detection in an optical frequency domain reflectometer and a time gating optical frequency domain reflectometer, and detect the change information of beat frequency shift along with time caused by the phase modulation of high-frequency vibration on sweep frequency detection optical signals on the optical fiber front section to any position to be detected on a sensing optical fiber 5 (namely, obtain a moving curve of backward Rayleigh scattering spectral domain fingerprints corresponding to the position to be detected L on the space in the whole pulse width), so as to obtain the correct instantaneous optical frequency shift corresponding to the position to be detected, thereby eliminating the influence of the beat frequency shift on vibration demodulation, and then according to the corrected instantaneous beat frequency, measuring the frequency spectrum or the phase change of backward Rayleigh scattering light of the position to be detected, realizing the strain detection without crosstalk on the whole optical fiber and improving the response bandwidth of a sensing system.
According to the vibration detection method of the high-frequency-response distributed optical fiber acoustic wave sensor provided by the invention, as shown in fig. 1, the vibration detection method comprises the high-frequency-response distributed optical fiber acoustic wave sensor, wherein the high-frequency-response distributed optical fiber acoustic wave sensor comprises a laser module, an optical fiber coupler 2, an optical fiber circulator 4, a sensing optical fiber 5, a coherent detection module 6, a data acquisition card 7 and a data processor 8;
laser output by the laser module is divided into probe light and local light through the optical fiber coupler 2, the probe light is input into the sensing optical fiber 5 through the optical fiber circulator 4 to form backward Rayleigh scattered light, the backward Rayleigh scattered light is input into the coherent detection module 6 through the optical fiber circulator 4, the local light is input into the coherent detection module 6, the coherent detection module 6 can beat the backward Rayleigh scattered light and the local light to form electric signal output, the data acquisition card 7 can acquire the electric signal, and the data processor 8 can process the electric signal; the laser module adopts a frequency-sweeping laser 1, and the frequency-sweeping laser 1 can output a frequency-sweeping optical pulse string; or, the laser module adopts a narrow linewidth laser, the high-frequency response distributed optical fiber acoustic wave sensor further comprises a radio frequency signal module and an optical modulator, the optical modulator is arranged between the optical fiber coupler 2 and the optical fiber circulator 4, the radio frequency signal module can input a sweep frequency radio frequency pulse string signal to the optical modulator, and the probe light can form a sweep frequency light pulse string through the optical modulator. The power of the detection light is greater than that of the local light, and the detection light input into the optical fiber circulator 4 is a sweep frequency light pulse string; preferably, the optical fiber amplifier further comprises an optical fiber amplifier 3, the optical fiber amplifier 3 is arranged between the optical fiber coupler 2 and the optical fiber circulator 4, the detection light is input into the optical fiber circulator 4 after being subjected to power amplification through the optical fiber amplifier 3, and the optical fiber amplifier 3 adopts an erbium-doped optical fiber amplifier. The data acquisition card 7 comprises a dual-channel data acquisition card. The optical fiber coupler 2 adopts a single-mode optical fiber coupler with a coupling ratio of 90 to 10.
Example 1:
the embodiment provides a distributed vibration detection system based on an optical frequency domain reflectometer, where the optical frequency domain reflectometer includes a swept-frequency laser 1, an optical fiber coupler 2, an optical fiber circulator 4, a sensing optical fiber 5, a coherent detection module 6, a data acquisition card 7, and a data processor 8, where: the frequency-sweeping laser 1 outputs a high-power and large-bandwidth frequency-sweeping optical pulse string, the optical pulse string is divided into two paths, one path has higher optical power and is input to a sensing optical fiber 5 as detection light through an optical fiber circulator 4, and the other path has lower optical power and is input to a coherent detection module 6 as local light; backward Rayleigh scattered light generated by the sensing optical fiber 5 enters a coherent detection module 6 through an optical fiber circulator 4; the backward Rayleigh scattered light is divided into light in X and Y polarization states in the coherent detection module 6, and the light is marked as S-X light and S-Y light respectively; similarly, local light is also divided into two states, L-X and L-Y; the light in two states of the backward Rayleigh scattering light and the light in two states of the corresponding local light are respectively subjected to beat frequency, and then are respectively subjected to photoelectric conversion into electric signals in two states of I-X and I-Y and output; and finally, the I-X state electric signals and the I-Y state electric signals are respectively acquired and processed by the data acquisition card 7 and the data processor 8.
Example 2
The embodiment provides a distributed vibration detection system based on a time-gated optical frequency domain reflectometer, wherein the time-gated optical frequency domain reflectometer comprises a radio frequency signal module, a narrow linewidth laser, an optical fiber coupler 2, an optical modulator, an optical fiber circulator 4, a sensing optical fiber 5, a coherent detection module 6, a data acquisition card 7 and a data processor 8, wherein: the radio frequency signal module comprises a radio frequency signal generator and a radio frequency signal amplifier which are connected, and inputs a sweep frequency radio frequency pulse train signal to the optical modulator; high-coherence and high-power laser output by the narrow linewidth laser is divided into two paths by the optical fiber coupler 2, one path has lower optical power and is input into the coherent detection module 6 as local light, and the other path has higher optical power and is input into the optical modulator; the optical modulator outputs a sweep frequency optical pulse string which is input to a sensing optical fiber 5 through an optical fiber circulator 4; backward Rayleigh scattered light generated by the sensing optical fiber 5 enters a coherent detection module 6 through an optical fiber circulator 4; the backward Rayleigh scattered light is divided into light in X and Y polarization states in the coherent detection module 6, and the light is marked as S-X light and S-Y light respectively; similarly, local light is also divided into two states, L-X and L-Y; the light in two states of the backward Rayleigh scattering light and the light in two states of the corresponding local light are respectively subjected to beat frequency, and then are respectively subjected to photoelectric conversion into electric signals in two states of I-X and I-Y and output; and finally, the I-X state electric signals and the I-Y state electric signals are respectively acquired and processed by the data acquisition card 7 and the data processor 8.
The vibration detection method of the high-frequency-response distributed optical fiber acoustic wave sensor further comprises the following steps of:
step 1: after the data acquisition card 7 acquires the electric signals, a two-dimensional array is formed by adopting a time-frequency analysis method and marked according to the emission time sequence; the time-frequency analysis method comprises short-time Fourier transform and wavelet transform.
And 2, step: and (3) obtaining a beat frequency-optical frequency domain fingerprint image of the backward Rayleigh scattering light at each position of the sensing optical fiber 5 during the nth detection after time-frequency analysis is carried out on the electric signal.
And step 3: detecting the translation amount of the backward Rayleigh scattering light at the position to be detected of the sensing optical fiber 5 in the beat frequency-optical frequency domain fingerprint image by adopting an image matching method, thereby obtaining the position of the backward Rayleigh scattering light at the position to be detected in the whole beat frequency-optical frequency domain fingerprint image;
and 4, step 4: according to the position of the backward Rayleigh scattering light at the position to be measured in the whole beat frequency-light frequency domain fingerprint image, the instantaneous light frequency shift corresponding to the position to be measured is obtained, and therefore the size of the strain at the position to be measured of the sensing optical fiber 5 is obtained.
The step 3 comprises the following steps:
step 3.1: using an image matching method, the image matching method comprising: taking a subregion corresponding to a certain position L to be detected of the sensing optical fiber 5 on a beat-light frequency domain fingerprint image of the backward Rayleigh scattering light obtained by the 1 st detection and at a certain time point t on time as a reference subregion, using image matching near the reference subregion on the beat-light frequency domain fingerprint image of the backward Rayleigh scattering light obtained by the nth detection to find the subregion to be detected which is most matched with the reference subregion, and obtaining the translation amount of the backward Rayleigh scattering light on the beat-light frequency domain fingerprint image of the sensing optical fiber 5 corresponding to the time and the space on the position L to be detected;
as shown in fig. 3, wherein:
(a) The method comprises the following steps A white dotted line frame is a sub-region at a certain position L to be detected of the sensing optical fiber 5 on the space and at a certain time point t in time on a beat frequency-optical frequency domain fingerprint image of the backward Rayleigh scattering light obtained by the 1 st detection;
(b) The method comprises the following steps The white dotted line frame is a sub-region to be detected which is most matched with the reference sub-region and is found by using image matching near the reference sub-region on the beat frequency-light frequency domain fingerprint image of the backward Rayleigh scattering light obtained by nth detection;
step 3.2: and (3) repeating the step 3.1 by changing the time point t until the position of the backward Rayleigh scattering light corresponding to the position L to be measured on the space in the whole beat frequency-optical frequency domain fingerprint image is obtained.
The step 4 comprises the following steps:
step 4.1: according to the position of the backward Rayleigh scattering light corresponding to the position L to be detected in the space in the whole beat frequency-light frequency domain fingerprint image obtained by the nth detection, obtaining the corresponding instantaneous light frequency shift of the position L to be detected;
step 4.2: and obtaining the frequency spectrum or phase change information of the backward Rayleigh scattering light corresponding to the position L to be detected, which is obtained by the nth detection, according to the instantaneous optical frequency shift, thereby obtaining the strain magnitude.
In step 4.2, according to the corresponding instantaneous optical frequency shift of the L position to be measured, obtaining the frequency spectrum frequency shift Delta ν of the backward Rayleigh scattering light of the position to be measured, wherein the dependent variable is
Wherein, K ε-ν Is the strain-frequency shift coefficient, v 0 Is the center frequency.
In step 4.2, according to the corresponding instantaneous optical frequency shift of the position L to be measured, the differential phase variation delta phi of the backward Rayleigh scattering light at the position L to be measured is obtained, and the dependent variable is
Wherein, K ε-φ Δ L is the differential distance, which is the strain-phase coefficient.
Further comprising the step 5: changing n and L, and repeating the steps 3-4, as shown in FIG. 4, until the change of the strain distribution on the whole sensing optical fiber 5 along with time is obtained, thereby realizing the strain detection without crosstalk on the whole optical fiber and improving the response bandwidth of the sensing system.
In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (10)
1. The vibration detection method of the high-frequency-response distributed optical fiber acoustic wave sensor is characterized by comprising the high-frequency-response distributed optical fiber acoustic wave sensor, wherein the high-frequency-response distributed optical fiber acoustic wave sensor comprises a laser module, an optical fiber coupler (2), an optical fiber circulator (4), a sensing optical fiber (5), a coherent detection module (6), a data acquisition card (7) and a data processor (8);
laser output by the laser module is divided into probe light and local light through an optical fiber coupler (2), the probe light is input into a sensing optical fiber (5) through an optical fiber circulator (4) to form backward Rayleigh scattered light, the backward Rayleigh scattered light is input into a coherent detection module (6) as signal light through the optical fiber circulator (4), the local light is input into the coherent detection module (6), the coherent detection module (6) can beat the backward Rayleigh scattered light and the local light to form electric signal output, a data acquisition card (7) can acquire the electric signal, and a data processor (8) can process the electric signal;
the detection light input into the optical fiber circulator (4) is a swept-frequency light pulse string;
the vibration detection method of the high-frequency response distributed optical fiber acoustic wave sensor further comprises the following steps:
step 1: the data acquisition card (7) acquires an electric signal;
step 2: time-frequency analysis is carried out on the electric signals to obtain a beat frequency-optical frequency domain fingerprint image of backward Rayleigh scattering light;
and step 3: detecting the translation amount of the backward Rayleigh scattered light at the position to be detected of the sensing optical fiber (5) in the beat frequency-optical frequency domain fingerprint image by adopting an image matching method, thereby obtaining the position of the backward Rayleigh scattered light at the position to be detected in the whole beat frequency-optical frequency domain fingerprint image;
and 4, step 4: according to the position of the backward Rayleigh scattering light of the position to be measured in the whole beat frequency-optical frequency domain fingerprint image, the instantaneous optical frequency shift corresponding to the position to be measured is obtained, and therefore the strain of the position to be measured of the sensing optical fiber (5) is obtained.
2. The vibration detection method of the high frequency response distributed optical fiber acoustic wave sensor according to claim 1, wherein in step 1, after the data acquisition card (7) acquires the electric signals, a time-frequency analysis method is adopted to form a two-dimensional array, and the two-dimensional array is marked according to the emission time sequence;
the time-frequency analysis method comprises short-time Fourier transform and wavelet transform.
3. The vibration detection method of the high-frequency-response distributed optical fiber acoustic wave sensor according to claim 1, wherein in the step 2, after time-frequency analysis is performed on the electrical signals, beat-frequency-optical-frequency-domain fingerprint images of backward rayleigh scattered light at each position of the sensing optical fiber (5) at the nth detection are obtained.
4. A vibration sensing method of a high frequency response distributed optical fiber acoustic wave sensor according to claim 3, wherein said step 3 comprises the steps of:
step 3.1: adopting an image matching method, wherein the image matching method comprises the following steps: taking a subregion corresponding to a position L to be detected of a sensing optical fiber (5) on a space and at a certain time point t on a beat-light frequency domain fingerprint image of the backward Rayleigh scattering light obtained by the 1 st detection as a reference subregion, using image matching near the reference subregion on the beat-light frequency domain fingerprint image of the backward Rayleigh scattering light obtained by the nth detection to find the subregion to be detected which is most matched with the reference subregion, and obtaining the translation amount of the backward Rayleigh scattering light on the position L to be detected of the sensing optical fiber (5) corresponding to the time and the space in the beat-light frequency domain fingerprint image;
step 3.2: and (3) repeating the step 3.1 by changing the time point t until the position of the backward Rayleigh scattering light corresponding to the position L to be measured on the space in the whole beat frequency-light frequency domain fingerprint image is obtained.
5. The method of detecting vibration of a high frequency response distributed optical fiber acoustic wave sensor according to claim 3, wherein said step 4 comprises the steps of:
step 4.1: according to the position of the backward Rayleigh scattering light corresponding to the position L to be detected in the space in the whole beat frequency-light frequency domain fingerprint image obtained by the nth detection, obtaining the corresponding instantaneous light frequency shift of the position L to be detected;
step 4.2: and obtaining the frequency spectrum or phase change information of the backward Rayleigh scattering light corresponding to the position L to be detected, which is obtained by the nth detection, according to the instantaneous optical frequency shift, thereby obtaining the strain magnitude.
6. The vibration detection method of a high frequency response distributed optical fiber acoustic wave sensor according to claims 4 and 5, further comprising the step of 5: changing n and L, and repeating the steps 3-4 until the change of the strain distribution on the whole sensing optical fiber (5) along with time is obtained.
7. The vibration detection method of the high-frequency-response distributed optical fiber acoustic wave sensor according to claim 5, wherein in step 4.2, the frequency spectrum frequency shift Δ ν of the backward rayleigh scattering light at the position to be measured is obtained according to the corresponding instantaneous optical frequency shift at the position to be measured L, and the amount of strain is
Wherein, K ε-ν Is the strain-frequency shift coefficient, v 0 Is the center frequency.
8. The vibration detection method of the high-frequency-response distributed optical fiber acoustic wave sensor according to claim 5, wherein in step 4.2, the differential phase variation quantity Δ φ of the backward Rayleigh scattering light at the position to be detected is obtained according to the corresponding instantaneous optical frequency shift at the position L to be detected, and the strain quantity is
Wherein, K ε-φ For the strain-phase coefficient, Δ L is the differential distance.
9. The vibration detection method of a high-frequency response distributed optical fiber acoustic wave sensor according to claim 1, wherein the laser module employs a swept-frequency laser (1), and the swept-frequency laser (1) is capable of outputting a swept-frequency optical pulse train.
10. The vibration detection method of the high-frequency-response distributed optical fiber acoustic wave sensor according to claim 1, wherein the laser module is a narrow-linewidth laser, the high-frequency-response distributed optical fiber acoustic wave sensor further comprises a radio frequency signal module and an optical modulator, the optical modulator is arranged between the optical fiber coupler (2) and the optical fiber circulator (4), the radio frequency signal module can input a swept-frequency radio frequency pulse train signal to the optical modulator, and the probe light can form a swept-frequency optical pulse train through the optical modulator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211227596.XA CN115824378A (en) | 2022-10-09 | 2022-10-09 | Vibration detection method of high-frequency-response distributed optical fiber acoustic wave sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211227596.XA CN115824378A (en) | 2022-10-09 | 2022-10-09 | Vibration detection method of high-frequency-response distributed optical fiber acoustic wave sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115824378A true CN115824378A (en) | 2023-03-21 |
Family
ID=85524429
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211227596.XA Pending CN115824378A (en) | 2022-10-09 | 2022-10-09 | Vibration detection method of high-frequency-response distributed optical fiber acoustic wave sensor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115824378A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116380140A (en) * | 2023-06-07 | 2023-07-04 | 山东省科学院激光研究所 | Distributed acoustic wave sensing system based on mean value filtering technology and measuring method thereof |
| CN117928714A (en) * | 2024-03-25 | 2024-04-26 | 山东省科学院激光研究所 | Distributed acoustic wave sensing system |
-
2022
- 2022-10-09 CN CN202211227596.XA patent/CN115824378A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116380140A (en) * | 2023-06-07 | 2023-07-04 | 山东省科学院激光研究所 | Distributed acoustic wave sensing system based on mean value filtering technology and measuring method thereof |
| CN116380140B (en) * | 2023-06-07 | 2023-11-03 | 山东省科学院激光研究所 | Distributed acoustic wave sensing system based on mean value filtering technology and measuring method thereof |
| CN117928714A (en) * | 2024-03-25 | 2024-04-26 | 山东省科学院激光研究所 | Distributed acoustic wave sensing system |
| CN117928714B (en) * | 2024-03-25 | 2024-06-11 | 山东省科学院激光研究所 | Distributed acoustic wave sensing system |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US20240011823A1 (en) | Method and Apparatus for Optical Sensing | |
| WO2021093181A1 (en) | Differential cotdr distributed acoustic sensing device and method based on heterogeneous double-sideband chirped pulse | |
| CN110132329B (en) | Stress, temperature and vibration composite detection optical fiber sensor and signal processing method | |
| US7515273B2 (en) | Method for measuring the brillouin shift distribution along an optical fiber based on the optical demodulation of the signals, and relevant apparatus | |
| US7859654B2 (en) | Frequency-scanned optical time domain reflectometry | |
| CN115824378A (en) | Vibration detection method of high-frequency-response distributed optical fiber acoustic wave sensor | |
| EP3477266B1 (en) | Distributed acoustic sensing device using different coherent interrogating light patterns, and corresponding sensing method | |
| CN104155619B (en) | Based on magnetostriction distribution probe beam deflation magnetic field sensing device and demodulation method | |
| CN102865914B (en) | Distributed optic fiber vibrating sensor | |
| CN109297581A (en) | It is a kind of for compensating the quadratic phase difference measurement method of frequency drift in phase sensitive optical time domain reflectometer | |
| CN108303626B (en) | Partial discharge ultrasonic measurement system and method based on distributed optical fiber sensing array | |
| CN108415067A (en) | A kind of earthquake wave measuring system based on microstructured optical fibers distribution sound wave sensing | |
| US20230152131A1 (en) | Techniques and apparatus for improved spatial resolution for locating anomolies in optical fiber | |
| CN116295778A (en) | Distributed acoustic wave sensing system and demodulation method thereof | |
| CN109088670B (en) | Method and system for determining sound wave signal | |
| US20240012760A1 (en) | Method and Apparatus for Optical Sensing | |
| US20230288231A1 (en) | Distributed acoustic sensing device and method | |
| CN113310564A (en) | System and method for measuring vibration parameter and temperature parameter of oil well casing | |
| Alekseev et al. | A Fiber Phase-Sensitive Optical Time-Domain Reflectometer for Engineering Geology Application | |
| CN112284511A (en) | Dynamic and static combined measurement distributed optical fiber sensing system | |
| Sun et al. | 2-D Phase Unwrapping in DAS with Transport of Intensity Equation | |
| CN110986814B (en) | Phase sensitive optical time domain reflection system with improved dynamic strain measurement range | |
| CN117073730B (en) | Optical fiber sensing system and optical fiber sensing method based on microwave photons | |
| Ibrahim et al. | The application of PCA on Փ-OTDR sensing system for vibration detection | |
| CN115235367A (en) | High-precision dual-frequency optical frequency domain reflectometer with large strain measurement range |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |