• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
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  • 优先权
    • 专利摘要:
    The embodiments of the present invention relate to a distributed fiber optic monitoring system and method, which relates to the field of fiber optic sensing. The system includes a laser device, an acousto-optic modulator, a phase matching interferometer, a photoelectric detector and a phase demodulation module. After entering the phase-matching interferometer, the Rayleigh backscatter light containing parameter information exiting the detection optical fiber enters the two arms of the phase-matching interferometer and the light from both arms of the The phase matching interferometer is phase modulated by the first modulation waveform and the second modulation waveform, respectively, and then interfere with each other to generate interference light. The photoelectric detector converts a light signal into an electrical signal and the phase demodulation module processes the electrical signal on the basis of the Hilbert algorithm to obtain the change of parameter of the environment under test. Processing with the Hilbert algorithm does not require the acquisition of modulation waveforms and it is sufficient that the amplitude difference between the first modulation wave and the second modulation wave is greater than or equal to a threshold of amplitude difference allowing the two arms of the phase-matching interferometer to have an optical phase difference of 2π.
    公开号:FR3085071A1
    申请号:FR1860522
    申请日:2018-11-15
    公开日:2020-02-21
    发明作者:Ying SHANG；Chen Wang；Chang Wang；Jiasheng NI；Chang Li；Bing CAO；Wen'an ZHAO；Sheng Huang；Yang Liu；Xiaohui Liu；Yingying Wang
    申请人:LASER INST OF SHANDONG ACADEMY OF SCIENCES；Laser Institute of Shandong Academy of Science；
    IPC主号:
    专利说明:

    P018034980
    Fiber optic distributed control system and method Technical area
    The present invention relates to the field of fiber optic detection, and, in particular, to a system and method for distributed control of optical fibers.
    Context of the invention
    Distributed fiber optic sensing technology enables continuous measurement over external physical parameters distributed along a geometric fiber optic path and is widely used in the areas of intelligent bridge, expressway, major building and gas line, etc. With respect to distributed fiber optic control, there are mainly two kinds of distributed control system, namely, distributed control systems based on intensity demodulation and distributed control systems based on phase demodulation , the intensity demodulation distributed control systems can only demodulate the information of variation of luminous intensity of Rayleigh backscatter light in a unit pulse and having a limited scope of application, whereas the distributed demodulation control systems of phase can demodulate the phase information of the interference light of the Rayleigh backscatter light in a unit pulse and a wide range of application scenarios. Currently, the phase demodulation solutions of a distributed phase demodulation control system mainly consist of two solutions, namely, phase-generated carrier demodulation (PGC) and 3x3 coupler.
    The PGC solution requires the addition of carrier and requires the acquisition of signal for interference light and modulation waves simultaneously, i.e., it needs to demodulate two signals at the same time, thus frequency and amplitude carrier requirements need to be strictly quantified to meet the requirement for system demodulation accuracy; moreover, the dynamic range of the system is limited by the carrier frequency. 3x3 coupler demodulation requires the simultaneous signal acquisition of three signals, which requires more data and complicates the system. The principle of 3x3 coupler demodulation is based on an angle of 120 °, but the 3x3 coupler actually produced does not precisely have 120 °, so the angle of the 3x3 coupler also affects demodulation accuracy.
    In summary, the process of acquiring demodulation data according to the state of the art is relatively complicated, and there are many factors affecting accuracy, resulting in poor accuracy of the acquired demodulation data.
    I
    PO 18034980
    P018034980
    summary
    It is an object of the present invention to provide a distributed fiber optic control system and method to improve the above problems. In order to achieve the object, the technical solution adopted in the present invention is as follows:
    According to a first aspect, an embodiment of the present invention relates to a distributed control system with optical fibers, comprising a laser device, an acousto-optical modulator, a phase-matching interferometer, a photoelectric detector and a demodulation module of phase. The laser device is configured to output continuous laser light, the continuous laser light being transmitted in the acousto-optical modulator and the acousto-optical modulator being configured to chop the continuous laser light into pulsed light. The pulsed light is transmitted in a detection optical fiber, the detection optical fiber being configured to exit, upon detection of an acoustic wave or vibration signal, a Rayleigh backscatter light containing the acoustic wave signal or vibration and Rayleigh backscatter light is transmitted into the phase-matching interferometer. The phase matching interferometer is configured to divide the Rayleigh backscatter light into a first part of Rayleigh backscatter light and a second part of Rayleigh backscatter light, to phase-modulate the first part of Rayleigh backscatter light by applying a first modulation wave to a first arm of the phase-matching interferometer, and to phase-modulating the second part of Rayleigh backscattering light by applying a second modulation wave to a second arm of the phase-matching interferometer , wherein the first part of the phase modulated Rayleigh backscattering light and the second part of the phase modulated Rayleigh backscattering light, with a phase difference therebetween in the range of 0-2tt, interfere with each other other to generate interference light. An amplitude difference between the first modulation wave and the second modulation wave is greater than or equal to an amplitude difference threshold allowing an optical phase difference between the two arms of the phase matching interferometer be 2π and each of the waveform of the first modulation wave and the waveform of the second modulation wave is any one of a triangular wave, a sawtooth wave and a sine wave . The phase matching interferometer is further configured to transmit the interference light into the photoelectric detector. The photoelectric detector is configured to convert the interference light into an electrical interference signal and to send the electrical interference signal to the phase demodulation module. The phase demodulation module is configured to demodulate in
    PO 18034980
    PO 18034980 phases the electrical interference signal based on a Hilbert algorithm to obtain acoustic wave or vibration information.
    Optionally, the above phase-matching interferometer includes a coupler and the first arm comprises a first piezoelectric ceramic, a first Faraday rotator mirror and a first optical fiber, the first optical fiber being wound on the first piezoelectric ceramic. Rayleigh backscattering light, after entering a first end of the coupler, has the first part which is taken out from a third end of the coupler to the first optical fiber and the first modulation wave is applied to the first piezoelectric ceramic to modulate in phase the first part of Rayleigh backscattering light. The first part of phase-modulated Rayleigh backscattering light travels through the first optical fiber and is reflected towards the third end by the first Faraday mirror-rotator.
    The second arm comprises a second piezoelectric ceramic, a second Faraday rotator mirror and a second optical fiber, the second optical fiber being wound on the second piezoelectric ceramic. The Rayleigh backscatter light, after entering the first end of the coupler, has the second part which exits from a fourth end of the coupler to the second optical fiber. The second modulation wave is applied to the second piezoelectric ceramic to phase-modulate the second part of Rayleigh backscattering light. The second part of phase-modulated Rayleigh backscattering light travels through the second optical fiber and is reflected towards the fourth end by the second Faraday mirror-rotator. The first part of phase-modulated Rayleigh backscattering light and the second part of phase-modulated Rayleigh backscattering light generate interference light which is output from a second end of the coupler to the photoelectric detector.
    Optionally, the coupler is a 2x2 coupler having a division ratio of 1: 1.
    Optionally, the first piezoelectric ceramic and the second piezoelectric ceramic each have a diameter in the range of 1 cm to 3 cm.
    Optionally, the system further includes a first amplifier and a circulator. A sequence of optical pulses, after being amplified by the first amplifier, enters a first end of the circulator and is transmitted from a second end of the circulator into the detection optical fiber and Rayleigh backscatter light is output from a third end from the circulator to the first end of the coupler.
    PO18034980
    PO18034980
    Optionally, the system further comprises a second amplifier and a filter, the Rayleigh backscatter light output from the third end of the circulator is sequentially amplified by the second amplifier and filtered by the filter, then transmitted to the first end of the coupler.
    Optionally, the phase demodulation module is configured to perform a Hilbert transformation on the electrical interference signal to obtain a Hilbert transformation signal and to obtain acoustic wave or vibration information based on the electrical signal d interference and Hilbert transformation signal.
    Optionally, the phase demodulation module is configured to do the following: obtaining a first differential signal by performing a differential operation on the Hilbert transformation signal, obtaining a first product signal by multiplying the first differential signal by the electrical interference signal, obtaining a second differential signal by performing a differential operation on the electrical interference signal, obtaining a second product signal by multiplying the transformation signal of Hilbert by the second differential signal, obtaining a difference signal by subtracting the second product signal from the first product signal, obtaining an integrated signal by performing an integral operation on the signal difference signal and obtaining acoustic wave or vibration information by performing filtering processing e on the integrated signal.
    According to a second aspect, an embodiment of the present invention relates to a distributed optical fiber control method, applicable to the distributed optical fiber control system described above according to the first aspect. The process includes:
    the laser device outputting continuous laser light to the acousto-optical modulator;
    the acousto-optic modulator chopping continuous laser light into pulsed light;
    bringing the pulsed light into the circulator through the first end and the circulator exiting the Rayleigh backscatter light through the third end;
    the phase-matching interferometer dividing the Rayleigh backscatter light into a first part of Rayleigh backscatter light and a second part of Rayleigh backscatter light, phase-modulating the first part of Rayleigh backscatter light by applying a first wave of modulation to a first arm of the phase-matching interferometer and phase-modulating the second part of Rayleigh backscattering light by applying a second modulation wave to a second arm of the phase-matching interferometer
    P018034980
    PO 18034980 phase, in which the first part of phase-modulated Rayleigh backscattering light and the second part of phase-modulated Rayleigh backscattering light, with a phase difference between them in a range of 0-2π, interfere with the other to generate interference light, an amplitude difference between the first modulation wave and the second modulation wave is greater than or equal to an amplitude difference threshold allowing an optical phase difference between the two arms of the phase-matching interferometer to be 2π and each of the waveform of the first modulation wave and the waveform of the second modulation wave is any one of a wave triangular, a sawtooth wave and a sine wave;
    the photoelectric detector converting the interference light into an electrical interference signal and sending the electrical interference signal to the phase demodulation module and the phase demodulation module being configured to do the following: performing a transformation of Hilbert on the sign! electrical interference to get a sign! of Hilbert transformation, obtaining a first differential signal by performing a differential operation on the signa! Hilbert transformation, obtaining a first product signal by multiplying the first differential signal by the electrical interference signal, obtaining a second differential signal by performing a differential operation on the electrical interference signal , obtaining a second product signal by multiplying the Hilbert transformation signal by the second differential signal, obtaining a sign! difference by subtracting the second product signal from the first product signal, obtaining an integrated signal by performing an integral operation on the difference signal, and obtaining acoustic wave or vibration information by performing a filtering processing on the integrated signal.
    The embodiments of the present invention relate to a distributed fiber optic control system and method, in which, when the phase-matching interferometer modulates in phase the acquired Rayleigh backscattering light, the Rayleigh backscattering light is divided into two parts and the two parts of Rayleigh backscatter light enter the two arms of the phase matching interferometer, respectively, and modulation waves are added thereto respectively to phase modulate the Rayleigh backscatter light; after phase modulation, the Rayleigh backscatter lights of the two arms of the phase matching interferometer have a phase difference between them in the range of 0-2π and interfere with each other to generate light interference; when performing phase demodulation based on the Hilbert algorithm, the phase demodulation module only needs to acquire the interference light signals and does not need to sample the signals modulation waves, as well,
    PO18034980
    PO18034980 on the one hand, a single channel acquisition is carried out and, on the other hand, the requirements concerning the amplitudes and waveforms of the added modulation waves are not as strict as those for the modulation waves in the solution PGC and it is sufficient that the amplitude difference between the modulation waves is greater than or equal to an amplitude difference threshold allowing an optical phase difference between the two arms of the phase-matching interferometer to be 2π. In addition, the waveform of each of the modulation waves is any of a triangular wave, a sawtooth wave and a sine wave. Therefore, compared to the three-channel acquisition of the 3x3 coupler solution and the acquisition of signa! to two channels of the PGC solution, ie the system according to the embodiments of the present invention has a simple structure and, moreover, since the system structure is simplified, the system failure rate is reduced, the amount of data processing of the system is reduced and the factors affecting the demodulation accuracy are thereby reduced, making it possible to acquire acoustic wave or vibration information from the environment in a more precise and practical manner.
    Other characteristics and advantages of the present invention will be presented in the following description and will become partly evident from the description or will be understood when implementing the embodiments of the present invention. The objects and other advantages of the present invention can be achieved and obtained by the structures specifically indicated in the description, the claims and the drawings.
    Brief description of the drawings
    In order to illustrate more clearly the technical solutions of the embodiments of the present invention, a brief description is made below of the drawings to be used in the embodiments. It should be understood that the following drawings illustrate only some of the embodiments of the present invention and should not be considered as limiting the scope and, for those skilled in the art, other attached drawings can be obtained from these. drawings without effort of invention.
    FIG. 1 is a block diagram of a distributed fiber optic control system according to an embodiment of the present invention;
    FIG. 2 is another block diagram of the distributed fiber optic control system according to an embodiment of the present invention;
    FIG. 3 is a flow diagram of a distributed optical fiber control method according to an embodiment of the present invention; and FIG. 4 is a flow diagram of a Hilbert algorithm according to an embodiment of the present invention.
    PO 18034980
    PO18034980
    Reference signs:
    10-distributed control system with optical fibers; 60-filter; 120-laser device; 130-acousto-optic modulator; 140-circulator; 200-phase match interferometer; 220-coupler; 300-photoelectric detector; and 400-phase demodulation module.
    Detailed description of embodiments
    In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the drawings of the embodiments of the present invention. Apparently, the embodiments described are some of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and illustrated in the present drawings can generally be arranged and designed in a variety of different configurations. Thus, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of protection of the present invention, but is purely representative of the selected embodiments of the present invention. All other embodiments which are obtained by those skilled in the art without effort of invention on the basis of the embodiments of the present invention should be covered by the scope of protection of the present invention.
    It should be noted that similar signs and letters designate similar elements in the following drawings, and therefore, once a certain element is defined in a figure, it need not be yet defined and explained in the figures. following figures. Furthermore, in the description of the present invention, terms such as "first" and "second" are only used for a differentiated description and cannot be understood as an indication or implication of relative importance.
    Referring to FIG. 1 and FIG. 2, an embodiment of the present invention relates to a distributed control system with optical fibers 10. The system 10 comprises a laser device 120, an acousto-optical modulator 130, a phase correspondence interferometer 200, a photoelectric detector 300 and a phase demodulation module 400. The laser device 120 is configured to exit the continuous laser light, the continuous laser light being transmitted in the acousto-optical modulator 130 and the acousto-optical modulator 130 is configured to chop the continuous laser light in pulsed light. Pulsed light is transmitted in a detection optical fiber, the detection optical fiber is configured to exit, upon detection of an acoustic or vibration wave signal, from the Rayleigh backscatter light containing the wave signal acoustic or
    PO18034980
    PO 18034980 vibration and the Rayleigh backscatter light is transmitted in the phase matching interferometer 200. The phase matching interferometer 200 is configured to divide the Rayleigh back scattering light into a first part of Rayleigh back scattering light and into a second part of Rayleigh backscattering light, for phase modulating the first part of Rayleigh backscattering light by applying a first modulation wave to a first arm of the phase matching interferometer 200, and for phase modulating the second part of Rayleigh backscatter light by applying a second modulation wave to a second arm of the phase-matching interferometer 200, the first part of phase-modulated Rayleigh backscatter light and the second part of phase-modulated Rayleigh backscatter light, with a phase difference between el within a range of 0-2π, interfering with each other to generate interference light. An amplitude difference between the first modulation wave and the second modulation wave is greater than or equal to an amplitude difference threshold allowing an optical phase difference between the two arms of the phase-matching interferometer 200 d be 2π and each of the waveform of the first modulation wave and the waveform of the second modulation wave is any one of a triangular wave, a sawtooth wave and a sine wave. The phase matching interferometer 200 is further configured to transmit the interference light into the photoelectric detector 300. The photoelectric detector 300 is configured to convert the interference light into an electrical interference signal and to send the signal interference signal to the phase demodulation module 400. The phase demodulation module 400 is configured to demodulate in phase the electrical interference signal based on a Hilbert algorithm in order to obtain acoustic wave information or vibration.
    Furthermore, according to an embodiment of the present invention, when the phase matching interferometer 200 modulates in phase the acquired Rayleigh backscattering light, the Rayleigh backscattering light is divided into two parts and the two parts of backscattering light Rayleigh enters the two arms of the 200-phase phase interferometer, respectively, and modulation waves are added to it respectively to phase-modulate the Rayleigh backscatter light. After phase modulation, the Rayleigh backscatter lights of the two arms of the phase matching interferometer 200 have a phase difference between them in the range of 0-2π and interfere with each other to generate light interference. When performing phase demodulation on the basis of a Hilbert algorithm, the phase demodulation module 400 only needs to acquire the interference light signals and does not need to sample the signals modulation waves. So,
    PO18034980
    PO 18034980 on the one hand, a single channel acquisition is carried out and on the other hand, the requirements concerning the amplitude and the waveform of the added modulation waves are not as strict as those for the modulation waves in the PGC solution and it is sufficient that the amplitude difference between the modulation waves is greater than or equal to an amplitude difference threshold allowing a difference in optical phase between the two arms of the phase correspondence interferometer 200 d 'be of 2tt. In addition, the waveform is any one of a triangular wave, a sawtooth wave and a sine wave. Consequently, compared to the three-channel acquisition of the 3x3 coupler solution and the two-channel signal acquisition of the PGC solution, the system according to the embodiments of the present invention has a simple structure and, further, as the system structure is simplified, the system failure rate is reduced, the amount of system data processing is reduced and the factors affecting the demodulation accuracy are thereby reduced, making it possible to acquire information from acoustic wave or vibration of the environment more precisely and conveniently.
    Furthermore, according to an embodiment of the present invention, when the phase demodulation module 400 acquires the acoustic wave and environmental vibration information on the basis of the Hilbert algorithm, the condition that the phase difference between the light of the two arms of the phase matching interferometer 200 after phase modulation is in the range of 0-2π needs to be satisfied. So that the phase difference between the light of the two arms of the phase-matching interferometer 200 after phase modulation modulation is within the range of 0-2π, the difference in amplitude between the first modulation wave and the second wave added modulation only needs to meet the condition of being greater than or equal to an amplitude difference threshold allowing an optical phase difference between the two arms of the phase matching interferometer 200 to be 2π .
    Optionally, the phase correspondence interferometer 200 comprises a coupler 220 and the first arm of the phase correspondence interferometer 200 comprises a first piezoelectric ceramic, a first Faraday mirror-rotator and a first optical fiber, the first optical fiber being wound on the first piezoelectric ceramic. The Rayleigh backscattering light, after entering a first end of the coupler, has the first part which exits from a third end of the coupler 220 to the first optical fiber and the first modulation wave is applied to the first piezoelectric ceramic for modulate in phase the first part of Rayleigh backscattering light. The first part of phase modulated Rayleigh backscattering light travels through the first optical fiber and
    PO 18034980
    PO18034980 is reflected back to the third end by Faraday's first rotator mirror.
    The second arm of the phase matching interferometer 200 includes a second piezoelectric ceramic, a second Faraday rotator mirror and a second optical fiber, the second optical fiber being wound on the second piezoelectric ceramic. The Rayleigh backscatter light, after entering the first end of the coupler 220 has the second part which has come out of a fourth end of the coupler 220 to the second optical fiber. The second modulation wave is applied to the second piezoelectric ceramic to phase-modulate the second part of Rayleigh backscattering light. The second part of phase-modulated Rayleigh backscattering light travels through the second optical fiber and is reflected back to the fourth end by the second Faraday mirror-rotator.
    Optionally, the sensing optical fiber is placed in the environment under test and transmits Rayleigh backscatter light with parameter information into the phase matching interferometer 200 when the parameters of the environment under test are changed. It should be noted that, according to the embodiments of the present invention, the parameter information can be acoustic wave or vibration information, but are not simply limited to acoustic wave or vibration information and according to the specific embodiments, the parameter information may be other information.
    Optionally, the system 10 further comprises a first amplifier and a circulator 140. A sequence of optical pulses, after having been amplified by the first amplifier, enters a first end of the circulator 140 and is transmitted from a second end of the circulator 140 in the detection optical fiber and the Rayleigh backscattering light is output from a third end of the circulator 140 towards the first end of the coupler 220.
    Optionally, the system further comprises a second amplifier and a filter 60, the Rayleigh backscatter light output from the third end of the circulator 140 is sequentially amplified by the second amplifier and filtered by the filter 60, then transmitted to the first end of the coupler. 220.
    Furthermore, according to an embodiment of the present invention, there are no particular limits concerning the waveform of the first modulation wave and the waveform of the second modulation wave, which can be triangular waves, sawtooth waves or sine waves, as long as the condition that the highest frequency fc of the modulation waves is half the sampling rate fs
    PO 18034980
    PO18034980 of the phase demodulation system, that is to say, the condition c < 2 Jx is satisfied. At the same time, the first modulation wave and the second modulation wave can be used separately or in combination. For example, when the first modulation wave is applied to the first piezoelectric ceramic, the second modulation wave may not be applied to the second piezoelectric ceramic; but the second modulation wave can also be applied to the second piezoelectric ceramic. Furthermore, in the case where the first modulation wave and the second modulation wave are simultaneously added, when the waveform of the first modulation wave is selected to be a triangular wave, the waveform of the second Modulation waveform can be selected as any one of a triangular wave, a sawtooth wave and a sine wave. It is sufficient that the amplitude difference between the first modulation wave and the second modulation wave is greater than or equal to an amplitude difference threshold allowing an optical phase difference between the two arms of the phase-matching interferometer 200 to be 2tt. Therefore, the selection for the waveform of the first modulation wave and the waveform of the second modulation wave is relatively flexible and more practical, which allows the practicality and convenience of the distributed fiber control system. optics.
    Furthermore, with reference to FIG. 2, the laser device 120 is configured to output a continuous laser light of narrow line width. The narrow line width continuous laser light is transmitted to the acousto-optic modulator 130. The acousto-optic modulator 130 is configured to chop the received continuous laser light of narrow line width into sequences of optical pulses. The sequence of optical pulses, after being amplified by the first amplifier, enters a first end of the circulator 140 and is transmitted from the second end of the circulator 140 into the detection optical fiber. The detecting optical fiber exits, upon detection of an acoustic wave or vibration signal, from the Rayleigh backscatter light containing the acoustic wave or vibration signal and the Rayleigh backscatter light is output from a third end of the circulator 140 towards the phase correspondence interferometer 200.
    Furthermore, in FIG. 2, AOM is the acousto-optic modulator 130, capable of converting the laser light emitted by the laser device 120 into pulsed light. EDFA is an amplifier and C1, C2 and C3 are respectively the first end of the circulator 140, the second end of the circulator 140 and the third end of the circulator 140. PD is the photoelectric detector 300.
    Optionally, the first amplifier and the second amplifier may be erbium-doped optical fiber amplifiers.
    POl 8034980
    PO 18034980
    Optionally, the coupler 220 can be a 2x2 coupler 220 having a light division ratio of 1: 1.
    Optionally, each of the first piezoelectric ceramic and the second piezoelectric ceramic has a diameter in the range of 1 cm to 3 cm.
    Furthermore, in FIG. 2, Q1, Q2, Q3 and Q4 are respectively the first end of the coupler 220, the second end of the coupler 220, the third end of the coupler 220 and the fourth end of the coupler 220. Each of the PZTs is a piezoelectric ceramic, the piezoelectric ceramic being characterized in that when the voltage applied across the two ends of the piezoelectric ceramic changes, the size of the piezoelectric ceramic also changes. Each of the FRMs is a Faraday rotator-mirror that is configured to reflect modulated light, for example, the Faraday mirror-rotator can reflect the first part of Rayleigh backscattered light modulated in phase back to the third end of the coupler 220 ; and the second Faraday rotator mirror can reflect the second part of Rayleigh backscattered light modulated in return phase towards the fourth end of the coupler 220.
    Optionally, the first part of phase-modulated Rayleigh backscattering light and the second part of phase-modulated Rayleigh backscattering light generate an interference light signal which is output from the second end of the coupler 220 to the photoelectric detector 300. The photoelectric detector 300 converts the interference light signal into an electrical interference signal and sends the electrical interference signal to the phase demodulation module 400.
    Optionally, the phase demodulation module 400 is configured to perform a Hilbert transformation on the electrical interference signal in order to obtain a Hilbert transformation signal and to obtain acoustic wave or vibration information based on the electrical interference signal and Hilbert transformation signal.
    Optionally, the phase demodulation module 400 is configured to do the following: obtaining a first differential signal by performing a differential operation on the Hilbert transformation signal, obtaining a first product signal by multiplying the first differential signal by the electrical interference signal, obtaining a second differential signal by performing a differential operation on the electrical interference signal, obtaining a second product signal by multiplying the signal by Hilbert transformation by the second differential signal, obtaining a differential signal by subtracting the second product signal from the first product signal, obtaining an integrated signal by performing an integral operation on the differential signal and the obtaining
    PO 18034980
    PO 18034980 acoustic wave or vibration information by performing a filtering treatment on the signa! integrated.
    Optionally, referring to FIG. 3, an embodiment of the present invention relates to a distributed optical fiber control method, applicable to the distributed optical fiber control system 10 described according to the first aspect above. The specific implementation of the present invention is further understood in connection with the method, the method comprising:
    S100: the laser device emerging from the laser light continues towards the acousto-optic modulator;
    S200: the acousto-optic modulator chopping continuous laser light into pulsed light;
    S300: bringing the pulsed light into the circulator through the first end and the circulator exiting the Rayleigh backscatter light through the third end;
    S400: ('phase-matched interferometer dividing Rayleigh backscatter light into a first part of Rayleigh backscatter light and a second part of Rayleigh backscatter light, phase modulating the first part of Rayleigh backscatter light by applying a first modulation wave to a first arm of the phase-matching interferometer and phase-modulating the second part of Rayleigh backscattering light by applying a second modulation wave to a second arm of the phase-matching interferometer, the first part of phase-modulated Rayleigh backscatter light and the second part of phase-modulated Rayleigh backscatter light, with a difference between them in a range of 0-2π, interfere with each other to generate interference light , a difference in amplitude between the first modulate wave ion and the second modulation wave is greater than or equal to an amplitude difference threshold allowing an optical phase difference between the two arms of the phase-matching interferometer to be 2π and each of the form of the wave of the first modulation wave and the waveform of the second modulation wave is any one of a triangular wave, a sawtooth wave and a sine wave;
    S500: the photoelectric detector converting the interference light into an electrical interference signal and transmitting the electrical interference signal to the phase demodulation module and
    S600: the phase demodulation module being configured to perform the following: carrying out a Hilbert transformation on the electrical interference signal to obtain a Hilbert transformation signal, obtaining a first differential signal in performing an operation
    PO 18034980
    FOI 8034980 differential on the Hilbert transformation signal, obtaining a first product signal by multiplying the first differential signal by the electrical interference signal, obtaining a second differential signal by performing a differential operation on the electrical interference signal, obtaining a second product signal by multiplying the Hilbert transformation signal by the second differential signal, obtaining a difference signal by subtracting the second product signal from the first signal product, obtaining an integrated signal by performing an integral operation on the difference signal, and obtaining acoustic wave or vibration information by performing filtering processing on the integrated signal.
    In addition, the above algorithms are all implemented by system hardware and a, b, c, d, e, f and g in FIG. 4 each represent a signal, a representing an interference signal, b representing a Hilbert transformation signal, c representing a first differential signal, d representing a second differential signal, e representing a first product signal, f representing a second signal of product, g representing a difference signal, and h representing an integrated signal.
    Furthermore, as can be seen from FIG. 4, the aforementioned steps are such that the interference signal a is transformed into a signal b by Hilbert transformation, the signal b is subjected to a differential operation by a differentiator to obtain a sign! c, the signal c is multiplied by the interference signal a in order to obtain a signal e, the interference signal a is subjected to a differential operation to obtain a signal d, the signal b is multiplied by the signal d so to obtain a signal f, the signal f is subtracted from the signal e in order to obtain a signal g, the signal g is subjected to an integral operation in order to obtain a signal h and the signal h is filtered to finally obtain information acoustic wave / vibration. As can be seen from the aforementioned Hilbert algorithm, only the electrical interference signal is required in the final algorithm-based processing. Therefore, the method is relatively simple and easy to implement and has a high practicality.
    The embodiments of the present invention relate to a fiber optic distributed control system and method. The system includes a laser device, an acousto-optic modulator, a phase matching interferometer, a photoelectric detector and a phase demodulation module. The laser device is configured to exit continuous laser light, the laser light being transmitted in the acousto-optical modulator and the acousto-optical modulator is configured to chop the continuous laser light into pulsed light. The pulsed light is transmitted in a detection optical fiber, the optical fiber being configured to exit, upon detection of an acoustic wave or vibration signal, from the Rayleigh backscatter light containing the acoustic wave signal or of
    PO18034980
    PO 18034980 vibration, and Rayleigh backscatter light is transmitted to the phase-matched interferometer. The phase matching interferometer is configured to divide the Rayleigh backscatter light into a first part of Rayleigh backscatter light and a second part of Rayleigh backscatter light, to phase-modulate the first part of Rayleigh backscatter light by applying a first modulation wave to a first arm of the phase-matching interferometer and for phase-modulating the second part of Rayleigh backscattering light by applying a second modulation wave to a second arm of the phase-matching interferometer, the first part of Rayleigh backscattered light in phase and the second part of Rayleigh backscattered light in phase, with a phase difference between them within a range of 0-2π, interfering with each other to generate interference light. An amplitude difference between the first modulation wave and the second modulation wave is greater than or equal to an amplitude difference threshold allowing an optical phase difference between the two arms of the phase-matched interferometer to be of 2π and each of the waveform of the first modulation wave and the waveform of the second modulation wave is any one of a triangular wave, a sawtooth wave and a sine wave. The phase matching interferometer is further configured to transmit the interference light into the photoelectric detector. The photoelectric detector is configured to convert the interference light into an electrical interference signal and to send the electrical interference signal to the phase demodulation module. The phase demodulation module is configured to phase demodulate the electrical interference signal based on a Hilbert algorithm to obtain acoustic wave or vibration information. When the phase-matching interferometer modulates the acquired Rayleigh backscattering light in phase, the Rayleigh backscattering light is divided into two parts and the two parts of the Rayleigh backscattering light enter the two arms of the phase-matching interferometer , respectively, and modulation waves are added respectively to phase modulate the Rayleigh backscatter light; after phase modulation, the Rayleigh backscatter lights of the two arms of the phase matching interferometer have a phase difference between them in the range of 0-2π and interfere with each other to generate light interference; when performing phase demodulation based on the Hilbert algorithm, the phase demodulation module only needs to acquire the interference light signals and does not need to sample the signals modulation waves, thus, on the one hand, a single-channel acquisition is carried out and, on the other hand, the requirements concerning the amplitude and waveform of the added modulation waves
    PO18034980
    PO 18034980 are not as strict as those for the modulation waves in the PGC solution and it is sufficient that the amplitude difference between the modulation waves is greater than or equal to an amplitude difference threshold allowing a phase difference optic between the two arms of the phase correspondence interferometer to be 2π. In addition, the waveform is any one of a triangular wave, a sawtooth wave and a sine wave. Consequently, compared to the three-channel acquisition of the 3x3 coupler solution and the two-channel signal acquisition of the PGC solution, the system according to the embodiments of the present invention has a simple structure and, further, as the system structure is simplified, the system failure rate is reduced, the amount of system data processing is reduced and the factors affecting the demodulation accuracy are thereby reduced, making it possible to acquire information from acoustic wave or vibration of the environment more precisely and conveniently.
    The above description is only preferable embodiments of the present invention which are not used to restrict the present invention. For those skilled in the art, the present invention may have various changes and variations. All modifications, equivalent substitutions, improvements, etc. in the spirit and principle of the present invention will all be covered by the scope of protection of the present invention.
    权利要求:
    Claims (9)
    [1" id="c-fr-0001]
    PO 18034980
    Claims:
    1. Distributed fiber optic control system (10), characterized in that it comprises a laser, an acousto-optical modulator (130), a phase correspondence interferometer (200), a photoelectric detector (300) and a phase demodulation module (400), in which the laser is configured to exit continuous laser light which is transmitted to the acousto-optical modulator (130) and the acousto-optical modulator (130) is configured to chop continuous laser light in pulsed light;
    the pulsed light is transmitted in a detection optical fiber, the detection optical fiber is configured to exit, upon detection of an acoustic or vibration wave signal, from the Rayleigh backscatter light containing the wave signal acoustic or vibration and Rayleigh backscatter light is transmitted to the phase matching interferometer (200);
    the phase correspondence interferometer (200) is configured to divide the Rayleigh backscatter light into a first portion of Rayleigh backscatter light and a second portion of Rayleigh backscatter light, for phase modulation of the first portion of light Rayleigh backscatter by applying a first modulation wave to a first arm of the phase-matching interferometer (200) and for phase modulation of the second part of Rayleigh backscatter light by applying a second modulation wave to a second arm of the phase matching interferometer (200), wherein the first part of the phase modulated Rayleigh backscattering light and the second part of the phase modulated Rayleigh backscattering light, with a phase difference therebetween within a range 0-2π, interfere with each other to generate light interference; an amplitude difference between the first modulation wave and the second modulation wave is greater than or equal to an amplitude difference threshold allowing an optical phase difference between the two arms of the phase correspondence interferometer (200 ) to be 2π and each of the waveform of the first modulation wave and the waveform of the second modulation wave is any one of a triangular wave, a sawtooth wave and a sine wave;
    the phase matching interferometer (200) is further configured to transmit the interference light into the photoelectric detector (300);
    PO 18034980
    PO 18034980 the photoelectric detector (300) is configured to convert the interference light into an electrical interference signal and to send the electrical interference signal to the phase demodulation module (400) and the phase demodulation module ( 400) is configured to demodulate in phase the electrical interference signal based on a Hilbert algorithm to obtain acoustic wave or vibration information.
    [2" id="c-fr-0002]
    2. Distributed fiber optic control system (10) according to claim 1, characterized in that the phase correspondence interferometer (200) comprises a coupler (220), the first arm comprises a first piezoelectric ceramic, a first mirror - Faraday rotator and a first optical fiber, the first optical fiber is wound on the first piezoelectric ceramic, the Rayleigh backscattering light, after entering a first end of the coupler (220), has the first part which has come out of a third end of the coupler (220) to the first optical fiber and the first modulation probe is applied to the first piezoelectric ceramic to phase-modulate the first part of Rayleigh backscatter light, the first part of Rayleigh back modulated phase is travels through the first optical fiber and is reflected towards the third end by the first Faraday rotator mirror and the second arm comprises a second piezoelectric ceramic, a second Faraday rotator mirror and a second optical fiber, the second optical fiber is wound on the second piezoelectric ceramic, the Rayleigh backscatter light after being entering the first end of the coupler (220) at the second part which leaves a fourth end of the coupler (220) towards the second optical fiber, the second modulation wave is applied to the second piezoelectric ceramic to phase-modulate the second part of Rayleigh backscatter light, the second part of phase modulated Rayleigh backscatter light travels through the second optical fiber and is reflected towards the fourth end by the second Faraday mirror-rotator, the first part of backscatter light Rayleigh modulated in phase and the second by Rayleigh phase modulated backscatter light tie generates interference light which is output from a second end of the coupler (220) to the photoelectric detector (300).
    [3" id="c-fr-0003]
    3. Distributed fiber optic control system (10) according to claim 2, characterized in that the coupler (220) is a 2x2 coupler (220) having a light division ratio of 1: 1.
    P018034980
    PO 18034980
    [4" id="c-fr-0004]
    4. Distributed fiber optic control system (10) according to claim 2, characterized in that the first piezoelectric ceramic and the second piezoelectric ceramic each have a diameter in the range of 1 cm to 3 cm.
    [5" id="c-fr-0005]
    5. Distributed fiber optic control system (10) according to claim 2, characterized in that the system further comprises a first amplifier and a circulator (140), a sequence of optical pulses, after being amplified by the first amplifier, enters a first end of the circulator (140) and is transmitted from a second end of the circulator (140) to the detection optical fiber and the Rayleigh backscatter light is output from a third end of the circulator (140) to the first end of the coupler (220).
    [6" id="c-fr-0006]
    6. Distributed fiber optic control system (10) according to claim 5, characterized in that the system further comprises a second amplifier and a filter (60), the Rayleigh backscatter light output from the third end of the circulator (140 ) is sequentially amplified by the second amplifier and filtered by the filter (60), then transmitted to the first end of the coupler (220).
    [7" id="c-fr-0007]
    7. Distributed fiber optic control system (10) according to claim 1, characterized in that the phase demodulation module (400) is configured to perform a Hilbert transformation on the electrical interference signal to obtain a signal of Hilbert transformation and to obtain acoustic wave or vibration information based on the electrical interference signal and the Hilbert transformation signal.
    [8" id="c-fr-0008]
    8. Distributed fiber optic control system (10) according to claim 7, characterized in that the phase demodulation module (400) is configured to do the following: obtaining a first differential signal by performing a differential operation on the Hilbert transformation signal, obtaining a first product signal by multiplying the first differential signal by the signal! interference signal, obtaining a second differential signal by performing a differential operation on the interference electrical signal, obtaining a second product signal by multiplying the signal! Hilbert transformation by the second differential signal, obtaining a difference signal by subtracting the second product signal from the first product signal, obtaining an integrated signal by performing an integral operation on the difference signal signal and obtaining acoustic wave or vibration information by performing filtering processing on the integrated signal.
    PO 18034980
    PO 18034980
    [9" id="c-fr-0009]
    9. A distributed fiber optic control method, applicable to the distributed fiber optic control system (10) according to any one of claims 1 to 8, characterized in that the method comprises:
    a laser device (120) outputting continuous laser light to the acousto-optical modulator (130);
    the acousto-optic modulator (130) chopping continuous laser light into pulsed light;
    bringing the pulsed light into the circulator (140) through the first end and the circulator (140) exiting the Rayleigh backscatter light through the third end;
    the phase correspondence interferometer (200) dividing the Rayleigh backscatter light into a first part of Rayleigh backscatter light and a second part of Rayleigh backscatter light, phase-modulating the first part of Rayleigh backscatter light by applying a first modulation wave to a first arm of the phase-matching interferometer (200) and phase-modulating the second part of Rayleigh backscattering light by applying a second modulation wave to a second arm of the phase-matching interferometer (200), wherein the first part of phase-modulated Rayleigh backscattering light and the second part of phase-modulated Rayleigh backscattering light, with a phase difference therebetween in a range of 0-2π, interfere with each other to generate an interference light, a difference in amplitude ude between the first modulation wave and the second modulation wave is greater than or equal to an amplitude difference threshold allowing an optical phase difference between the two arms of the phase matching interferometer (200) to be of 2π and each of the waveform of the first modulation wave and the waveform of the second modulation wave is any one of a triangular wave, a sawtooth wave and a sine wave;
    the photoelectric detector (300) converting the interference light into an electrical interference signal and transmitting the electrical interference signal to the phase demodulation module (400) and the phase demodulation module (400) being configured to perform the following: carrying out a Hilbert transformation on the electrical interference signal to obtain a Hilbert transformation signal, obtaining a first differential signal by performing a differential operation on the signal! Hilbert transformation, obtaining a first product signal by multiplying the first signal
    PO 18034980
    PO 18034980 differential by the electrical interference signal, obtaining a second signal! differential by performing a differential operation on the signa! electrical interference, obtaining a second product signal by multiplying the Hilbert transform signal by the second differential signal, obtaining a difference signal by subtracting the second product signal from the first signal product, obtaining an integrated signal by performing an integral operation on the difference signal and obtaining acoustic wave or vibration information by performing filtering processing on the integrated signal.
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    法律状态:
    2019-11-28| PLFP| Fee payment|Year of fee payment: 2 |
    2020-05-08| PLSC| Publication of the preliminary search report|Effective date: 20200508 |
    2020-11-27| PLFP| Fee payment|Year of fee payment: 3 |
    2021-11-26| PLFP| Fee payment|Year of fee payment: 4 |
    优先权:
    申请号 | 申请日 | 专利标题
    CN201810946238.1|2018-08-17|
    CN201810946238.1A|CN108981767B|2018-08-17|2018-08-17|Optical fiber distributed monitoring system and method|
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