• 专利附录
  • 专利说明
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    • 专利摘要:
    The present invention provides a fiber optic distributed sensor monitoring system, which belongs to the field of distributed fiber optic sensor techniques. The system comprises a signal light generation device, a first optical coupler, a detection optical fiber, an optical beam splitter, a first polarization controller, a second polarization controller, a first interference modulation device, a second interference modulation device and a demodulation device. An interference modulation is performed by the first interference modulation device on the first linearly polarized light output from the first polarization controller and is performed by the second interference modulation device on the second linearly polarized light output from the first polarization light. second polarization controller, and then a first interference signal output from the first interference modulation device and a second interference signal output from the second interference modulation device are demodulated to obtain a corresponding detected signal. Therefore, it can be guaranteed as much as possible that the detected signal will not be lost, and that the signal-to-noise ratio of the distributed fiber optic sensor monitoring system will actually be improved.
    公开号:FR3059776A1
    申请号:FR1752006
    申请日:2017-03-13
    公开日:2018-06-08
    发明作者:Ying SHANG；Chen Wang；Chang Wang；Jiasheng NI；Xiaohui Liu；Zhihui Sun；Wen'an ZHAO；Yingying Wang；Qingchao Zhao；Long Ma；Bing CAO
    申请人:Laser Inst Of Shandong Academy Of Science；Laser Institute of Shandong Academy of Science；
    IPC主号:
    专利说明:

    Holder (s): LASER INSTITUTE OF SHANDONG ACADEMY OF SCIENCE.
    Extension request (s)
    Agent (s): REGIMBEAU.
    FR 3 059 776 - A1 (04 FIBER OPTIC SENSOR DISTRIBUTED MONITORING SYSTEM.
    The present invention provides a distributed fiber optic sensor monitoring system, which belongs to the field of distributed fiber optic sensor techniques. The system comprises a signal light generation device, a first optical coupler, a detection optical fiber, an optical beam splitter, a first polarization controller, a second polarization controller, a first interference modulation device, a second interference modulation device and a demodulation device. Interference modulation is performed by the first interference modulation device on the first linearly polarized light delivered by the first polarization controller and is performed by the second interference modulation device on the second linearly polarized light delivered by the second polarization controller, and then a first interference signal from the first interference modulation device and a second interference signal from the second interference modulation device are demodulated to obtain a corresponding detected signal. Therefore, it can be guaranteed as much as possible that the detected signal will not be lost, and that the signal-to-noise ratio of the fiber-optic distributed sensor monitoring system will actually be improved.
    i
    OPTICAL FIBER DISTRIBUTED SENSOR MONITORING SYSTEM
    TECHNICAL AREA
    The present invention relates to the field of distributed optical fiber sensor techniques, and particularly to a distributed optical fiber sensor monitoring system.
    PRIOR ART
    With the rapid development of the national economy, the demands of society for energy, particularly oil and gas resources, are increasing. In the national energy strategy, the construction and development of the storage and transport of oil and gas are linked to the overall strategy which provides a stable, economical and secure energy guarantee in the long term for economic construction and national social development. Pipeline transportation is the fifth most important mode of transportation, with the exception of road, rail, marine and air transportation, and its state of development directly reflects the level of the transportation industry. a country. Thus, pipeline leak monitoring technology has become a hotspot for scientists and engineers.
    Because it has the advantages of a large detection space, a single optical fiber with two detection and transmission capabilities of the ι
    light, simple structure, ease of use, low signal acquisition cost per unit length, high profitability, etc., the distributed fiber optic sensor technique is widely applied to monitor pipeline leaks. In an existing distributed fiber optic acoustic monitoring system, Rayleigh backscatter signals of different unit length sections on a detection optical fiber are used as the carrier of a detected signal, and phase change analysis is further performed on the Rayleigh backscatter signals at the corresponding positions, so as to measure the detected signal. However, since the Rayleigh backscatter signal is very weak and environmental noise can easily change a polarization state of light during transmission, the detected signal is caused to be immersed in the noise signal, which causes the system to not obtain the corresponding detected signal by demodulation.
    DESCRIPTION OF THE INVENTION
    In view of this, an object of the present invention is to provide a surveillance system with a distributed fiber optic sensor, so as to effectively mitigate the above-mentioned problem.
    In order to achieve the above object, embodiments of the present invention provide the following technical solutions.
    An embodiment of the present invention provides a fiber optic distributed sensor monitoring system, which includes: a signal light generating device, a first optical coupler, a detection optical fiber, an optical beam splitter, a first polarization controller, a second polarization controller, a first interference modulation device, a second interference modulation device and a demodulation device, where the detection optical fiber is configured to detect a detected signal. The signal light generated by the first signal light generating device is input, via the first optical coupler, into the detection optical fiber. Rayleigh backscatter light carrying the detected signal, in the detection optical fiber, is returned to the first optical coupler, and is entered into the optical beam splitter through the first optical coupler, and is then divided into a first beam of light and a second beam of light through the optical beam splitter. The first light beam is processed by the first polarization controller to become a first linearly polarized light which then strikes the first interference modulator, and the second light beam is processed by the second polarization controller to become a second linearly polarized light which also then strikes the second interference modulator, where the polarization directions of the first linearly polarized light and the second linearly polarized light are in a predetermined relationship. The demodulation device is configured to demodulate a first interference signal delivered by the first interference modulation device and a second interference signal delivered by the second interference modulation device, to obtain the detected signal.
    In a preferred embodiment of the present invention, each of the first polarization controller and the second polarization controller is a polarization controller of the optical fiber coil type, the polarization controller of the optical fiber coil type comprising a coil of optical fiber wound on an external wall of a tubular piezoelectric ceramic. An input end of the optical fiber coil of the first polarization controller is coupled to a first beam splitting end of the optical beam splitter, and an output end of the optical fiber coil of the first polarization controller is coupled to the demodulation device. An input end of the fiber optic coil of the second polarization controller is coupled to a second beam splitting end of the optical beam splitter, and an output end of the fiber optic coil of the second polarization controller is coupled to the demodulation device. The system further includes a voltage output device, and each of the tubular piezoelectric ceramic of the first polarization controller, tubular piezoelectric of the second polarization and the demodulation device is electrically connected to the voltage output device.
    In a preferred embodiment of the present invention, the optical fiber coil is a λ / 4 optical fiber coil.
    In a preferred embodiment of the present invention, the polarization controller of the optical fiber coil type further comprises a first housing, where the optical fiber coil wound on the external wall of the tubular piezoelectric ceramic is conditioned to the interior of the first accommodation.
    ceramic controller
    In a preferred embodiment of the present invention, the polarization controller of the fiber optic coil type further comprises a motor and a transmission shaft, where a rotary motor shaft is connected to the transmission shaft, and the motor is connected, via the drive shaft, to a rotation fitting arranged at a lower part of the first housing. The motor of the first polarization controller and the motor of the second polarization controller are both electrically connected to the voltage output device. The motor of the first polarization controller is configured to rotate the optical fiber coil of the first polarization controller, to allow the optical fiber coil to deliver the first linearly polarized light. The motor of the second polarization controller is configured to rotate the optical fiber coil of the second polarization controller, to allow the optical fiber coil to deliver the second linearly polarized light.
    In a preferred embodiment of the present invention, the polarization controller of the optical fiber coil type further comprises a second housing, where the first housing, in which the optical fiber coil wound on the outer wall of the piezoelectric ceramic tubular is conditioned, is arranged inside the second housing. The second housing is provided with a first opening, a second opening and a third opening, the first opening being configured to allow the input of the drive shaft, the second opening being configured to allow the output of a coil input from the fiber optic coil, and the third opening being configured to allow output from a coil output from the fiber optic coil.
    polarization end, polarization end interferometer,
    In a preferred embodiment of the present invention, the directions of polarization of the first linearly polarized light and the second linearly polarized light are orthogonal to each other.
    In a preferred embodiment of the present invention, the first interference modulation device comprises a first fiber optic interferometer, the second interference modulation device comprises a second fiber optic interferometer, and the demodulation device comprises a first polarization beam combiner, a first photoelectric detector and a data processor. An input end of the first fiber optic interferometer is coupled to an output of the first controller of an input end of the second fiber optic is coupled to an output of the second controller of an output end of the first fiber optic interferometer and an output end of the second fiber optic interferometer are both coupled to an input end of the first polarized beam combiner, an output end of the first polarized beam combiner is coupled to an input end of the first detector photoelectric, and an output end of the first photoelectric detector is electrically connected to the data processor. The first linearly polarized light forms the first interference signal after having undergone an interference treatment applied by the first fiber optic interferometer, and the second linearly polarized light forms the second interference signal after having undergone an interference treatment applied by the second one a fiber optic interferometer. The first interference signal and the second interference signal both enter the first polarized beam combiner, and are converted, after being combined by the first polarized beam combiner, into an electrical signal by the first detector photoelectric, and then enter the data processor. The data processor is configured to process the electrical signal to obtain the detected signal.
    In a preferred embodiment of the present invention, the first interference modulation device further comprises a second optical coupler, the second interference modulation device further comprises a third optical coupler, the demodulation device further comprises a second polarization beam combiner, a third polarization beam combiner, a second photoelectric detector and a third photoelectric detector, the first fiber optic interferometer includes a first 3x3 coupler, and the second fiber optic interferometer includes a second 3x3 coupler . The output end of the first polarization controller is coupled to a first port of the second optical coupler, a second port of the second optical coupler is coupled to a first port of the first 3x3 coupler, a third port of the second optical coupler is coupled to the input end of the first polarized beam combiner, a second port of the first 3x3 coupler is coupled to an input end of the second polarized beam combiner, and a third port of the first 3x3 coupler is coupled to an end of input of the third polarized beam combiner. The output end of the second polarization controller is coupled to a first port of the third optical coupler, a second port of the third optical coupler is coupled to a first port of the second 3x3 coupler, a third port of the third optical coupler is coupled to the input end of the first polarized beam combiner, a second port of the second 3x3 coupler is coupled to the input end of the second polarized beam combiner, and a third port of the second 3x3 coupler is coupled to the input end of the third polarized beam combiner. An output end of the second polarized beam combiner is coupled to an input end of the second photoelectric detector, an output end of the third polarized beam combiner is coupled to an input end of the third photoelectric detector, and a the output end of the second photoelectric detector and an output end of the third photoelectric detector are both electrically connected to the data processor.
    In a preferred embodiment of the present invention, each of the first fiber optic interferometer and the second fiber optic interferometer is a Michelson fiber optic interferometer.
    In the fiber optic distributed sensor monitoring system provided by the embodiments of the present invention, the Rayleigh backscatter light carrying the detected signal is divided by the optical beam splitter into the first light beam and the second beam light, and the first light beam and the second light beam are processed by the first polarization controller and the second polarization controller into the first linearly polarized light and the second linearly polarized light, respectively, the polarization directions of the first linearly polarized light and the second linearly polarized light being in a predetermined relationship. Interference modulation is performed on the first linearly polarized light and the second linearly polarized light by the first interference modulation device and the second interference modulation device, respectively, and then the first interference signal delivered by the first interference modulation device and the second interference signal delivered by the second interference modulation device are demodulated by the demodulation device in order to obtain a corresponding detected signal. Therefore, it can be guaranteed as much as possible that the detected signal will not be lost, and that the signal-to-noise ratio of the fiber optic distributed sensor monitoring system will actually be improved.
    BRIEF DESCRIPTION OF THE DRAWINGS
    In order to more clearly describe the technical solutions of the embodiments of the present invention, the drawings used for the embodiments will be briefly presented below. It should be understood that the drawings below simply show certain embodiments of the present invention, and therefore should not be considered as limiting the scope of the invention. For a person skilled in the art, other relevant drawings could also be obtained in the light of these drawings, without any inventive effort.
    FIG. 1 shows a structural diagram of a surveillance system with a distributed optical fiber sensor proposed by an embodiment of the present invention;
    ίο Figure 2 shows a diagram of a structure of a polarization controller of the optical fiber coil type proposed by an embodiment of the present invention, as seen from a first angle;
    FIG. 3 shows a diagram of the structure of the polarization controller of the optical fiber coil type proposed by the embodiment of the present invention, as seen from another angle;
    FIG. 4 shows a diagram of another structure of the polarization controller of the optical fiber coil type proposed by an embodiment of the present invention, as seen from a first angle;
    FIG. 5 shows a diagram of a second housing of the polarization controller of the optical fiber coil type proposed by an embodiment of the present invention, as seen from another angle;
    FIG. 6 shows another structural diagram of the surveillance system with distributed fiber optic sensor proposed by an embodiment of the present invention;
    FIG. 7 shows the structural diagram of a phase-demodulated carrier demodulation algorithm proposed by an embodiment of the present invention;
    FIG. 8 shows yet another structural diagram of the surveillance system with a distributed optical fiber sensor proposed by an embodiment of the present invention; and FIG. 9 shows the structural diagram of a 3 × 3 coupler demodulation algorithm proposed by an embodiment of the present invention.
    In the figures: 1 - surveillance system with distributed fiber optic sensor; 10 - signal light generating device; 20 - first circulator; 30 - optical fiber detection; 40 3059776 optical beam splitter; 51 - first polarization controller; 52 - second polarization controller; 50 - polarization controller of the fiber optic coil type; 501 - spool of optical fiber; 502 - first accommodation; 503 - rotation fitting; 504 - coil input; 505 - engine; 506 second accommodation; 507 - coil input; 508 - coil input fixing point; 509 - drive shaft; 510 - coil output; 511 - spool outlet fixing point; 512 - first opening; 513 - second opening; 514 - coil output; 515 - third opening; 61 - first interference modulation device; 610 - second circulator; 611 - first 3x3 coupler; 62 - second circulation pump modulation device
    620 - third 3x3 coupler; 70 701, 711 - first interference;
    ; 621 - second demodulation;
    polarization beam combiner; 712 - second polarization beam combiner; 713 - third polarization beam combiner; 702, 721 first photoelectric detector; 722 - second photoelectric detector; 723 - third photoelectric detector; 703, 730 - data processor; 80 - voltage output device.
    DETAILED DESCRIPTION OF EMBODIMENTS In an existing distributed optical fiber acoustic monitoring system, Rayleigh backscatter signals of different unit length sections on a detection optical fiber are used as the carrier of a detected signal, and a phase change analysis is further performed on the Rayleigh backscatter signals at the corresponding positions, so as to measure the detected signal. However, since the Rayleigh backscatter signal is very weak and environmental noise can easily change a polarization state of light during transmission, the detected signal is caused to be immersed in the noise signal, which causes the system to not obtain the corresponding detected signal by demodulation.
    In view of this, an embodiment of the present invention provides a fiber optic distributed sensor monitoring system to alleviate the aforementioned problem that the detected signal is caused to be immersed in the noise signal, which fact that the system does not obtain the corresponding detected signal by demodulation, since the Rayleigh backscatter signal is very weak and environmental noise can easily change the polarization state of light during transmission.
    In order to make the object, the technical solutions and the advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below, together with the drawings of the embodiments of the present invention. Apparently, the embodiments described are simply certain, but not all of the embodiments of the present invention. Generally, the components of the embodiments of the present invention, as described and shown in the drawings in this document, can be arranged and designed in various different configurations.
    Thus, the following detailed description of embodiments of the present invention which are provided in the drawings is not intended to limit the scope of the present invention as claimed, but "upper", "interior" "left" , "Right", are based on the simply depicts selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments, obtained by one skilled in the art without inventive effort, should fall within the scope of protection of the present invention.
    It should be noted that the reference symbols and similar letters represent similar elements in the drawings which follow. Thus, once a certain element has been defined in a figure, it will not be necessary to further define and explain the element in the following figures.
    In describing the present invention, it should be clarified that the orientation or position relationships indicated by terms such as "lower", and outer "orientation or position relationships shown in the drawings, or the relationships of orientation or position that a product according to the present invention is generally positioned in use, and these terms are used only to facilitate the description of the present invention and to simplify the description, rather than to indicate or imply that the device or element concerned must be in a specific orientation or configured and implemented in a specific orientation, and thus, they should not be interpreted as limiting the present invention. In addition, terms such as "first" and "second" are simply used for a differential description, and cannot be interpreted as indicating or implying material importance.
    In describing the present invention, it should further be clarified that, unless otherwise specified or defined, terms such as "arrange", "connect", "connect electrically" and "couple" should be interpreted in a broad sense. For example, it may be a direct link or coupling, or it may also be an indirect link or coupling via an intermediate means, or it may be '' act of an internal communication between two elements. The term “couple” here represents an optical coupling between optical devices. For a person skilled in the art, the specific meanings of the terms mentioned above in the present invention could be understood depending on the specific circumstances.
    As shown in Figure 1, an embodiment of the present invention provides a distributed fiber optic sensor monitoring system 1, which includes a signal light generating device 10, a first optical coupler, a detection optical fiber 30, an optical beam splitter 40, a first polarization controller 51, a second polarization controller 52, a first interference modulation device 61, a second interference modulation device 62 and a demodulation device 70.
    In the present embodiment, the signal light generating device 10 is used to generate signal light, and enters the signal light into the detection optical fiber 30 via the first optical coupler. The signal light generating device 10 can comprise an ultra narrow line width laser and an acousto-optical modulator. The laser emitted from the ultra narrow line width laser enters the acousto-optical modulator, and the continuous laser is modulated by the acousto-optical modulator in pulsed laser with a pulse duration τ and a period T, c ' is at 3059776 to say that the signal light is a pulsed laser. In addition, the signal light generating device 10 can further comprise a first optical amplifier and a first optical filter with ultra narrow bandwidth successively coupled. The first optical amplifier is used to enhance the energy of the signal light to increase a propagation distance of the signal light. The first ultra narrow bandwidth optical filter is used to filter out pulses with a longer pulse duration from the light signal. In practice, a narrow bandwidth pulsed laser can also be adopted for the signal light generation device 10.
    The detection optical fiber 30 is a single optical fiber distributed over a surface of a target to be measured, and is used to detect a detected signal. For example, in the case where the target to be measured is a pipeline transporting oil or gas, the detection optical fiber 30 is distributed over the surface of the pipeline; and if there is a leak in the pipeline, oil or gas would flow out of the leak point due to a pressure difference between the inside and the outside of the pipeline, thereby producing an acoustic wave. The acoustic wave caused by the exit of oil or gas at the vanishing point, i.e. a detected signal, would produce a disturbance on the signal light transmitted in the detection optical fiber 30. Given that Rayleigh scattering is part of the intrinsic loss of an optical fiber, in this embodiment, the Rayleigh backscatter light in the detecting optical fiber 30 serves as the carrier of the detected signal, and the information concerning the disturbance which is caused by an external detected signal on the detection optical fiber 30 are detected by displaying a relationship between the loss and the length of the detection optical fiber 30.
    The first optical coupler can be a first circulator 20. The first circulator 20 comprises a first port, a second port and a third port. The signal light delivered by the signal light generating device 10 is entered into the first circulator 20 via the first port of the first circulator 20, and is delivered to the detection optical fiber 30 from the second port of the first circulator 20. The Rayleigh backscatter light carrying the detected signal, which is returned from the detection optical fiber 30, enters the second port and then is delivered from the third port to the optical beam splitter 40. Being since Rayleigh backscatter light is relatively weak, a second optical amplifier and a second ultra narrow bandwidth optical filter can be provided between the first circulator 20 and the optical beam splitter 40.
    The optical beam splitter 40 can be a 1x2 coupler, or can also be a splitter of other types; it is used to split the incident signal light into a first light beam and a second light beam. Preferably, the energy ratio of the divided light beams of the 1x2 coupler is 50:50. The optical beam splitter 40 includes a first beam splitting end and a second beam splitting end, where the first light beam is delivered by the first beam splitting end and the second light beam is delivered by the second beam splitting end.
    polarized polarized
    An input end of the first polarization controller 51 is coupled to the first beam splitting end of the optical beam splitter 40, and an input end of the second polarization controller 52 is coupled to the second beam splitting end of the optical beam splitter 40. The first light beam is supplied from the first beam splitting end to the first polarization controller 51, and the second light beam is delivered from the second beam splitting end to the second polarization controller 52. The first polarization controller 51 is used to control a polarization direction of the first light beam, that is, to convert the first light beam into a first linearly polarized light for its output. Correspondingly, the second polarization controller 52 is also used to control a polarization direction of the second light beam, that is, to convert the second light beam into a second linearly polarized light for its output. The polarization directions of the first linearly polarized light and the second linearly polarized light are in a predetermined relationship, regulating the first polarization controller 51 and the second polarization controller. Preferably, the directions of polarization of the linearly and linearly are predetermined as follows: the direction of polarization of the first linearly polarized light and the direction of polarization of the second linearly polarized light are orthogonal to each other. It should be clarified that the light directions of relation first second la in the polarized absolutely polarized from the polarization of the first light linearly and the second light linearly might not be orthogonal to each other, and that it There is a certain error, since they are influenced by the regulation accuracy on the first polarization controller 51 and the second polarization controller 52.
    In the present embodiment, each first polarization controller 51 and of the second polarization controller 52 can adopt a polarization controller of the fiber optic coil type. The specific structure and principle of the polarization controller of the optical fiber coil type will be presented below.
    As shown in Figure 2, the optical fiber coil type polarization controller 50 includes an optical fiber coil 501 wound on an outer wall of a tubular piezoelectric ceramic. The radius of curvature R (m, N) and the number of turns wound and a partial wave coefficient of the optical fiber coil 501 satisfy the following relational expression:
    / (w, jV) = - ar 2 Nm (1)
    In formula (1), a is a constant, for example, a = 0.133 for a single mode optical fiber with a core and a fiber cladding made from silicon dioxide; r is the radius of the optical fiber; N is the number of turns wound; and m is the partial wave coefficient.
    In the present embodiment, the optical fiber coil 501 is a λ / 4 optical fiber coil, which can be equivalent to a quarter wave plate. Specifically, a tubular piezoelectric ceramic with a radius R is selected, and m = 4 for the optical fiber coil of λ / 4, then a corresponding number of wound turns N is calculated according to formula (1). A single mode bending resistant optical fiber is preferably adopted as an optical fiber in the optical fiber coil 501. The single mode bending resistant optical fiber is wound, along a circumferential direction of the tubular piezoelectric ceramic, over the outer wall of the tubular piezoelectric ceramic over N turns. The bending of the optical fiber causes an anisotropic distribution of the stress in the cross section of the optical fiber, and the distribution of the refractive index of the optical fiber material is changed due to a photoelastic effect. Thus, an additional induced birefringence is produced, which causes a change in the state of polarization of a guided wave, so as to achieve control of the state of polarization. In this way, the optical fiber coil 501 is capable of delivering linearly polarized light with a direction of polarization required by a user.
    In a first aspect, however, since the first light beam and the second light beam could be partially polarized light, rather than standard elliptical polarized light, relatively precise linearly polarized light cannot be obtained by means an existing λ / 4 fiber optic coil; and, in another aspect, since the radius of curvature R of the optical fiber coil 501 is not precise, it influences the output of linearly polarized light from the optical fiber coil
    501, which is not beneficial for the demodulation of the fiber optic distributed sensor monitoring system 1. Consequently, in one embodiment of the present invention, the optical fiber coil of λ / 4 is wound on the outer wall of tubular piezoelectric ceramic. Due to an electromagnetic necking effect of the piezoelectric ceramic, the length and the bending radius of the optical fiber resistant to the single-mode bending wound on the external wall may be caused to change when the positive and negative electrodes of the piezoelectric ceramic are supplied, and thus an additional induced birefringence can be generated by the crushing of the optical fiber. Therefore, the parameters of the optical fiber coil
    501 can be finely adjusted by controlling the voltage applied to the piezoelectric ceramic, so as to allow the optical fiber coil 501 to deliver linearly polarized light.
    In addition, the polarization controller of the optical fiber coil type 50 further comprises a first housing 502, and the optical fiber coil 501 wound on the external wall of the tubular piezoelectric ceramic is packaged in the first housing 502. FIG. 2 shows a front view of the optical fiber coil type polarization controller 50, and Figure 3 shows a view from the left of Figure 2. Specifically, the piezoelectric ceramic after the winding is placed in the first housing
    502. As shown in Figure 3, the first housing
    502 is provided with a coil input 504 and a coil output 514. A coil input 507 of the fiber optic coil 501 is output from the coil input 504, and a coil output 510 of the coil of optical fiber 501 is output from the coil output 514. The coil input 507 comprises an input of the single-mode bending resistant optical fiber and an input of the positive electrode of the piezoelectric ceramic, and the coil output 510 includes an output of the optical fiber resistant to single-mode bending and an output of the negative electrode of the piezoelectric ceramic. An epoxy resin-based adhesive is poured into the first housing 502, so as to condition the optical fiber coil 501 wound on the external wall of the tubular piezoelectric ceramic inside the first housing 502. The first housing 502 can have sound insulation, vibration isolation and fixing capabilities.
    Furthermore, in order to more precisely control the direction of polarization of the linearly polarized light delivered by the optical fiber coil 501, as shown in Fig. 4, the polarization controller of the optical fiber coil type 50 further comprises a motor 505 and a transmission shaft 509, and a rotation connector 503 is arranged at a lower part of the first housing 502. A rotary shaft of the motor 505 is connected to the transmission shaft 509, and the motor 505 is connected to the rotation connector 503 arranged at the bottom of the first housing 502 via the transmission shaft 509. In this case, a deflection angle of the fiber optic reel 501 can be controlled by controlling the rotary shaft of the motor 505 so that it rotates in a direction ω, so as to control the direction of polarization of the linearly polarized light delivered by the spool of optical fiber 501. In the present embodiment, the motor 505 can be a stepping motor.
    The fiber optic spool 501 is a λ / 4 spool. When the plane of the coil is rotated by a, the direction of the linearly polarized light delivered by the optical fiber coil by λ / 4 is rotated by β, and the relationship between a and β is shown by formula (2).
    β = 4 (ΐ-ί) α (2)
    In formula (2), t is a constant reflecting the characteristic of the material of the optical fiber, and t = 0.08 for all doped silicon dioxide. As shown in FIG. 4, when the rotary shaft of the motor 505 rotates by a first predetermined angle, the drive shaft 509 is driven in rotation in the direction ω, and therefore, the spool of optical fiber 501 is driven to rotate a second predetermined angle in the direction ω, thereby allowing the plane of the spool of the optical fiber spool 501 to rotate from an initial position as shown in Figure 4 to a predetermined position, and by Therefore, allowing linearly polarized light with a desired direction of polarization to be delivered. The second predetermined angle can be set according to the desired direction of polarization, and the first predetermined angle is set according to the transmission ratio between
    The tree rotary motor 505 and the fiber coil optical of λ / 4. In Besides, as shown on the face 4, the polarization controller of coil type fiber
    optical 50 further comprises a second housing 506, and the first housing 502, in which the optical fiber coil 501 wound on the external wall of the tubular piezoelectric ceramic is conditioned, is arranged in the second housing 506. The second housing 506 has an acoustic insulation capacity, and thus the interference caused by an external acoustic signal on the polarization modulation of the optical fiber coil 501 can be effectively avoided. It should be clarified that FIG. 4 is a front view of the polarization controller of the fiber optic coil type 50, and that FIG. 5 is a view from the left of the second housing 50 6 shown in FIG. 4. As shown in FIG. 5, in order to allow the transmission shaft 509, the coil input 507 and the coil output 510 to pass through it, the second housing 506 is provided with a first opening 512 , a second opening 513 and a third opening 515. The first opening 512 is used to allow the input of the drive shaft 509, the second opening 513 is used to allow the output of the coil input 507 from the fiber optic spool 501, and the third opening 515 is used to allow the exit of the spool outlet 510 from the fiber optic spool 501. In order to prevent displacement of the spool inlet 507 and the coil output 510, the input of spool 507 and the spool outlet 510 are fixed, with an epoxy resin adhesive, at a spool inlet fixing point 508 and a spool outlet fixing point 511, respectively, as shown in figure 4.
    In use, an input end of the optical fiber coil 501 of the first polarization controller 51 (the input of the optical fiber resistant to single mode bending) is coupled to the first beam splitting end of the optical beam splitter 40, and an output end of the optical fiber coil 501 of the first polarization controller 51 (the output of the optical fiber resistant to single-mode bending) is coupled to the demodulation device 70.
    An input end of the fiber optic coil 501 of the second polarization controller 52 is coupled to the second beam splitting end of the optical beam splitter 40, and an output end of the fiber optic coil 501 of the second controller polarization device 52 is coupled to the demodulation device 70.
    In this case, in order to guarantee that the first polarization controller 51 and the second polarization controller 52 deliver linearly polarized light, and to allow the directions of polarization of the first linearly polarized light delivered by the first polarization controller 51 and of the second linearly polarized light output from the second polarization controller 52 are in the aforementioned predetermined relationship, the first polarization controller 51 and the second polarization controller 52 must be adjusted respectively. Thus, the surveillance system with distributed fiber optic sensor 1 proposed by the present embodiment further comprises a voltage output device which is electrically connected to the demodulation device 70. The first polarization controller 51 and the second controller bias 52 are both electrically connected to the voltage output device. Specifically, the piezoelectric ceramic in the first polarization controller 51 and the piezoelectric ceramic in the second polarization controller 52 are also both electrically connected to the voltage output device, and the motor 505 in the first polarization controller 51 and the motor 505 in the second polarization controller 52 are both electrically connected to the voltage output device.
    The voltage output device supplies a first voltage to the piezoelectric ceramic of the first polarization controller 51, and supplies a second voltage to the piezoelectric ceramic of the second polarization controller 52. With the effect of electromagnetic necking of the piezoelectric ceramic, the parameters of the optical fiber coils 501 of the first polarization controller 51 and of the second polarization controller 52 are finely adjusted, so as to allow the optical fiber coil 501 of the first polarization controller 51 to deliver the linearly polarized light and to the fiber optic coil 501 of the second polarization controller 52 to deliver the linearly polarized light.
    In addition, the voltage output device supplies a third voltage to the motor 505 of the first polarization controller 51, so that the plane of the coil of the first polarization controller 51 is deflected by a first angle, and at the same time, the first polarization controller 51 processes the first light beam entered into the first linearly polarized light. Correspondingly, the voltage output device supplies a fourth voltage to the motor 505 of the second polarization controller 52, so that the plane of the coil of the second polarization controller 52 is deflected by a second angle, and at the same time , the second polarization controller 52 processes the second light beam entered into the second linearly polarized light, and allows the polarization directions of the first linearly polarized light and the second linearly polarized light to be orthogonal to each other . The first voltage, the second voltage, the third forecast of the piezoelectric motor, this voltage and the fourth voltage are here fixed in accordance with the specifications.
    In the present embodiment, the first polarization controller 51 and the second polarization controller 52 adopt the polarization controller of the above-mentioned optical fiber coil type 50; and, therefore, compared to an existing polarization controller, the precision of controlling the polarization state and the polarization direction can be improved effectively by the 505 and ceramic which is beneficial for increasing the signal ratio on noise of the fiber optic distributed sensor monitoring system 1 proposed by the present embodiment.
    Of course, in addition to the polarization controller of the aforementioned optical fiber coil type 50, a quarter-wave plate, a combination of a quarter-wave plate and a half-wave plate, or other devices for polarization control can also be adopted for the first polarization controller 51 and the second polarization controller 52.
    In addition, the first interference modulation device 61 receives the first linearly polarized light delivered by the first polarization controller 51, modulates the first linearly polarized light into a first interference signal and delivers the first interference signal to the device. demodulation device 70. The second interference modulation device 62 receives the second linearly polarized light delivered by the second polarization controller 52, modulates the second linearly polarized light into a second interference signal and delivers the second interference signal to the demodulation device 70.
    The demodulation device 70 is used to demodulate the first interference signal delivered by the first interference modulation device 61 and the second interference signal delivered by the second interference modulation device 62, so as to obtain the signal detected.
    The embodiment of the present invention mainly provides two demodulation modes, the two demodulation modes corresponding respectively to the two specific implementations of the interference modulation device and of the demodulation device 70. The distributed sensor monitoring systems optical fiber 1 in the two specific implementations will be described respectively below.
    As a specific implementation, as shown in FIG. 6, the first interference modulation device 61 comprises a first fiber optic interferometer, the second interference modulation device 62 comprises a second fiber optic interferometer, and the demodulation device 70 comprises a first polarization beam combiner 701, a first photoelectric detector 702 and a data processor 703.
    An input end of the first fiber optic interferometer is coupled to an output end of the first polarization controller 51, and an input end of the second fiber optic interferometer is coupled to an output end of the second polarization controller 52 An output end of the first fiber optic interferometer and an output end of the second fiber optic interferometer are both coupled to an input end of the first polarization beam combiner 701, an output end of the first beam combiner bias 701 is coupled to an input end of the first photoelectric detector 702, and an output end of the first photoelectric detector 702 is electrically connected to the data processor 703.
    In the present embodiment, each of the first fiber optic interferometer and the second fiber optic interferometer is preferably a Michelson fiber optic interferometer.
    The first fiber optic interferometer includes a first 2x2 coupler, a first phase modulator, a first Faraday rotator mirror and a second Faraday rotator mirror. The second fiber optic interferometer includes a second 2x2 coupler, a second phase modulator, a third Faraday rotator mirror and a fourth Faraday rotator mirror.
    As shown in FIG. 6, the laser delivered by the laser with an ultra narrow line width enters the acousto-optical modulator, and the continuous laser is modulated by the acousto-optical modulator in pulsed laser with a pulse duration τ and a period T, and then the pulsed laser forms signal light after passing successively through the first optical amplifier and the first optical filter with ultra narrow bandwidth. Signal light enters an end C11 of the first circulator 20, and is transmitted into the detection optical fiber 30 of a length Y via an end C13 of the first circulator 20. The Rayleigh backscatter light carrying the detected signal, in the detection optical fiber 30, is returned to the end C13 of the first circulator 20, and is output via an end C12 of the first circulator 20, and then it enters an end E31 of the optical beam splitter 40 after passing successively through the second optical amplifier and the second ultra narrow bandwidth optical filter. Then, the signal delivered by the second ultra narrow bandwidth optical filter is divided by the optical beam splitter 40 into a first light beam and a second light beam, the first light beam entering through a first beam splitting end E32 of the optical beam splitter 40 in an end Q11 of the first polarization controller 51, and the second light beam entering via a second beam splitting end E33 of the beam splitter optic 40 in one end Q21 of the second polarization controller 52.
    The first linearly polarized light output from an end Q12 of the first polarization controller 51 enters an end Eli of the first coupler 2x2, and is divided by the first coupler 2x2, the light output from an end E13 of the first 2x2 coupler entering the first Faraday rotator mirror after passing through an optical fiber of length L1, and the light output from an end E14 of the first 2x2 coupler entering the second Faraday rotator mirror after passing through the first phase modulator. An optical fiber with a length L2 connects the first phase modulator and the second Faraday rotary mirror, where Ll> L2, and Ll - L2 = S. The two light beams are reflected back to the first coupler 2x2 by the first Faraday rotator mirror and the second Faraday rotator mirror, respectively, and interfere at the first 2x2 coupler to form the first interference signal. The first interference signal enters an end P41 of the first polarization beam combiner 701 via an end E12 of the first 2x2 coupler.
    The second linearly polarized light delivered from one end Q22 of the second polarization controller 52 enters an end E21 of the second coupler 2x2, and is divided by the second coupler 2x2, the light delivered from one end E23 of the second 2x2 coupler entering the third Faraday rotator mirror after passing through an optical fiber of length L1, and the light delivered from one end E24 of the second 2x2 coupler entering the fourth Faraday rotator mirror after passing through the second phase modulator. An optical fiber with a length L2 connects the second phase modulator and the fourth Faraday rotary mirror, where Ll - L2 = S. The two light beams are reflected back to the second coupler 2x2 by the third Faraday rotary mirror and the fourth Faraday rotator mirror, respectively, and interfere at the second 2x2 coupler to form the second interference signal. The second interference signal enters an end P42 of the first polarization beam combiner 701 via an end E22 of the second coupler 2x2. During this process, the voltage output device 80 supplies a carrier signal generated by phase F5 to the first phase modulator and to the second phase modulator for the carrier modulation.
    The first interference signal entering from the P41 end of the first polarization beam combiner 701 and the second interference signal entering from the P42 end form a total interference signal after being combined by the first polarized beam combiner 701. The total interference signal enters the first photoelectric detector 702 via an end P43 of the first polarized beam combiner 701. The first photoelectric detector
    702 converts the first interference signal and the second interference signal after they have been combined into an electrical signal, and delivers the electrical signal to the data processor 703 for the demodulation of the phase-generated carrier (PGC), in order to obtain a corresponding detected signal after demodulation. The demodulation of the carrier generated by phase can be carried out in hardware, or can also be carried out in software. When performed in hardware, the data processor
    703 can be an integrated circuit module; and when carried out in software, the data processor 703 can be a computer or a chip having a data processing function.
    Based on the light intensity detected by the first photoelectric detector 702, the data processor 703 can control the voltage output device 80 to emit an electrical signal F1 to control the piezoelectric ceramic of the second polarization controller 52, and for emitting an electrical signal F3 to control the piezoelectric ceramic of the first polarization controller 51, so as to allow the output of the first linearly polarized light and of the second linearly polarized light. In addition, the data processor 703 can control the voltage output device 80 to emit an electrical signal F2 to control the motor 505 of the second polarization controller 52, and to emit an electrical signal F4 to control the motor 505 of the first controller polarization 51, so as to regulate respectively the
    directions polarization of the first light polarized linearly and of the second light polarized linearly, so than the directions of
    polarization of the first linearly polarized light and the second linearly polarized light are orthogonal to each other.
    FIG. 7 shows a modular diagram of a phase-demodulated carrier demodulation algorithm adopted in the present embodiment. As shown in Figure 7, a detection signal is multiplied by a fundamental frequency signal at a first multiplier, and then enters a first low pass filter. The signal delivered from the first low-pass filter is transmitted to a first differentiator, and then enters one end of a subtractor after being multiplied by a signal from a second low-pass filter, for subtraction with a signal from a fourth multiplier. The detection signal is multiplied by a signal doubled in frequency at a second multiplier, and then enters the second low-pass filter. The signal delivered from the second low-pass filter is transmitted to a second differentiator, and then enters said one end of the subtractor after being multiplied by the signal from the first low-pass filter, for subtraction with the signal from the third multiplier. The two signals are transmitted to the subtractor simultaneously for their subtraction, and the difference obtained is transmitted to an integrator and then to a high pass filter, to obtain the signal detected by demodulation.
    According to the principle of light coherence, the light intensity I received by the first photoelectric detector 702 can be represented by:
    I = A + Bcos <t> (t) (3)
    In formula (3), A represents the average optical power of the total interference signal, B represents the amplitude of the total interference signal, B = kA, where k <1 and represents the visibility of the interference fringes. <ï> (t) represents a phase difference of the total interference signal. Assuming that <& (t) = Ccoscû 0 t + (p (t), formula (3) can be rewritten:
    I = A + Bcos [Ccos (jüot + <p (t)] (4)
    In formula (4), Ccosoot represents the carrier generated by phase, C represents the amplitude, and a> o represents the carrier frequency; and φ (t) = DcosG) s t + vj / (t). In the case where the detected signal is a sound field signal, Dcosœ s t represents a phase change which is caused by the sound field signal and detected by the detection optical fiber 30. D represents the amplitude, o s represents the frequency of the sound field signal, and Y | / (t) represents a slow change of an initial phase which is caused, for example, by environmental disturbances. The following formula is obtained by developing formula (4) with a Bessel function:
    QO
    I = A + B {[J o (C) + 2 ^ (-1) * J 2i (C) cos 2jfcû) 0 Z] cos φ (/) (5)
    -2 [Σ cos (2Â: + 1) ω ο φΐηψ (/)} k = 0
    In formula (5), J n (m) represents the value of a nth order Bessel function at a modulation depth m. As shown in figure 7, on the diagram of the carrier modulation generated by phase, a signal I after having been developed with the Bessel function is used as a detection signal, and it is multiplied by the fundamental frequency signal (with an amplitude G) and a signal doubled in frequency (with an amplitude H), respectively. In order to avoid signal extinction and distortion which could occur with fluctuation of an external interfering signal, differential cross multiplication (DCM) is performed on both signals, and the signals, after differential cross multiplication, are subjected to a differential amplification and integration operation, so as to be converted into:
    B 2 GHJi (C) J 2 (C) <p (t) (6)
    The following formula is obtained by substituting (p (t) = Dcosfi) s t + Y | / (t) in formula (6):
    B 2 GH Ji (C) J 2 (C) [Dcosœ s t + MJ (t)] (Ί)
    It can be seen from formula (7) that the signal obtained after integration contains the signal to be measured Dcosû) s t and external environmental information. The latter are generally a slowly varying signal, but can have a relatively large amplitude, and can thus be removed by filtering through the high pass filter. Finally, the output from the system is as follows:
    B 2 GHJi (C) J 2 (C) Dcosœ s t (8)
    The signal Dcosœ s t, which is the phase change which is caused by the sound field signal, i.e. the detected signal, and detected by the detection optical fiber 30, can be resolved according to the formula (8 ).
    As another specific implementation, as shown in FIG. 8, the first interference modulation device 61 comprises a second optical coupler and a first fiber optic interferometer, and the second interference modulation device 62 comprises a third optical coupler and a second fiber optic interferometer. The demodulation device 70 comprises a first polarization beam combiner 711, a second polarization beam combiner 712, a third polarization beam combiner 713, a first photoelectric detector 721, a second photoelectric detector 722, a third photoelectric detector 723 and a data processor 730.
    In the present embodiment, the first fiber optic interferometer includes a first 3x3 611 coupler, a first Faraday rotator mirror and a second Faraday rotator mirror, and the second fiber optic interferometer includes a second 3x3 621 coupler, a third Faraday rotator mirror and a fourth Faraday rotator mirror. The second optical coupler can be a second circulator 610, and the third optical coupler can be a third circulator 620.
    In this case, the difference from the above-mentioned implementation is that: the first linearly polarized light delivered from the end Q12 of the first polarization controller 51 enters an end Bll of the first coupler 3x3 611 after having passed successively through the ends C21 and C23 of the second circulator 610, and is divided by the first coupler 3x3 611, the light delivered from one end B14 of the first coupler 3x3 611 entering the first Faraday rotary mirror after be passed through an optical fiber of length L1, and the light delivered from one end B15 of the first 3x3 611 coupler entering the second Faraday rotator mirror after being passed through an optical fiber with a length L2, where Ll - L2 = S. The two light beams are reflected back to the first 3x3 611 coupler by the first rotating mirror r of Faraday and the second Faraday rotator mirror, respectively, and interfere at the level of the first 3x3 coupler to form the first interference signal. The first interference signal is divided into three beams of light. A first light beam enters one end C23 of the second circulator 610 via the end B11 of the first 3x3 coupler 611, and then enters a Pli end of the first polarized beam combiner 711 via one end C22 of the second circulator 610. A second light beam enters one end P21 of the second polarization beam combiner 712 via an end B12 of the first coupler 3x3 611. The third light beam enters one end P31 of the third polarized beam combiner 713 via an end B13 of the first 3x3 coupler 611.
    The second linearly polarized light delivered from the end Q22 of the second polarization controller 52 enters a end B21 of the second 3x3 coupler 621 after having passed successively through the ends C31 and C33 of the third circulator 620, and is divided by the second 3x3,621 coupler, the light delivered from one end B24 of the second 3x3,621 coupler entering the third Faraday rotator mirror after having passed through an optical fiber with a length L1, and the light delivered from a end B25 of the second 3x3 621 coupler entering the fourth Faraday rotator mirror after having passed through an optical fiber with a length L2, where Ll - L2 = S. The two light beams are reflected back to the second 3x3 621 coupler by the third Faraday rotator mirror and the fourth Faraday rotator mirror, respectively, and inter operate at the second 3x3 coupler to form the second interference signal. The second interference signal is also divided into three light beams. A first light beam is delivered to one end C33 of the third circulator 620 via the end B21 of the second 3x3 coupler 621, and then enters an end P12 of the first polarized beam combiner 711 via d one end C32 of the third circulator 620. A second light beam enters one end P22 of the second polarization beam combiner 712 via an end B22 of the second 3x3 coupler 621. The third light beam enters a end P32 of the third polarization beam combiner 713 via an end B23 of the second coupler 3x3 621.
    The light entering the ends P1 and P12 of the first polarization beam combiner 711 enters, after being combined by the first polarization beam combiner 711, into the first photoelectric detector 721 via an end P13, and is converted by the first photoelectric detector 721 into a first electrical signal, and is then entered into the data processor 730. The light entering the ends P21 and P22 of the second polarized beam combiner 712 enters, after having been combined by the second polarization beam combiner 712, in the second photoelectric detector 722 via an end P23, and is converted into a second electrical signal by the second photoelectric detector 722, and is then entered into the data processor 730. Light entering ends P31 and P32 of the third beam combiner x polarization 713 enters, after being combined by the third polarization beam combiner 713, into the third photoelectric detector 723 via an end P33, and is converted into a third electrical signal by the third photoelectric detector 723 , and is then entered into the data processor 730. The first electrical signal, the second electrical signal and the third electrical signal are transmitted simultaneously in the data processor 730 to undergo a 3x3 coupler demodulation algorithm, so as to obtain a corresponding detected signal by modulation.
    Based on the light intensity received by the first photoelectric detector 721, the second photoelectric detector 722 and the third photoelectric detector 723, the data processor 703 can control the voltage output device 80 to emit an electrical signal F6 to control the piezoelectric ceramic of the first polarization controller 51 and an electrical signal F8 for controlling the piezoelectric ceramic of the second polarization controller 52, so as to allow the output of the first linearly polarized light and the second linearly polarized light. In addition, the data processor 730 can control the voltage output device 80 to transmit an electrical signal
    F7 for controlling the motor 505 of the first polarization controller 51 and an electrical signal F9 for controlling the motor 505 of the second polarization controller 52, so as to regulate respectively the polarization directions of the first linearly polarized light and of the second polarized light linearly, so that the polarization directions of the first linearly polarized light and the second linearly polarized light are orthogonal to each other.
    It should be clarified that an improved 3x3 coupler demodulation algorithm is preferably adopted in the present embodiment. The improved 3x3 coupler demodulation algorithm effectively alleviates the problem that a distortion of the phase demodulation results from an error in an optical fiber angle of the 3x3 coupler. The principle of demodulation is as follows:
    A = D + I o cos Δφ
    B = D + l 0 cos (Aç) - 0) = D + I o (cosAç) cos0 + sin Δρ sin0) (10)
    C = D + I o cos (Δφ + 0) = D + 7 0 (cosAç, cos0 - sin Δφ sin0) (il) where A, B and C represent respectively three outputs of the 3x3 coupler, in which D represents a signal of direct current, Io represents the amplitude of the signal, Δφ represents the detected signal, and Θ is the optical fiber angle of the 3x3 coupler.
    Formulas (9), rewritten as follows:
    (10) and (11) can be
    ~ A ~ 1 0 1 ' I o οοδΔφ B = COS0 δϊηθ 1 : 7 0 sin Δφ VS COS0 -δΐηθ 1 D
    (12)
    Formula (13) can also be obtained from formula (12):
    I o cosAç) / „sinAç)
    D
    tl 1_ 1U_1
    In formula (13), T represents a matrix
    concerning 1 ' fiber optic angle of coupler with i ο Γ -1r = cosô sin0 1 cos0 -sin0 1 We can see from of the formula (13) that the calculation of Δφ no longer dependsdegrees of an ordinary 3x3 coupler. of the angle of 120 In addition, as shown on the figure 9, a
    differential processing, as shown in formula (14) and in formula (15), is carried out by the differentiators on signal A and signal B.
    / 0 cosA <p- (7 0 sinA <p) = I o 2 (Δφ) (οοδΔφ) 2 I o δΐηΔφ (/ 0 cosAp) = - / 0 2 (Δφ) (δϊηΔφ) 2
    After that, the signals, after differential processing, are subjected to a subtraction processing as shown in formula (16) by a subtractor:
    7 0 2 (Δφ) (cosA <p) 2 + / 0 2 (Δφ) (δϊηΔφ) 2 = 70 2 (Δφ) (16)
    During this time, signal A and signal B are processed by square risers, respectively, and then by a summator, to obtain the following formula:
    7θ 2 (cos Δφ) 2 + / 0 2 (sinA <jo) 2 = 70 2 (17)
    In addition, Δφ can be obtained by dividing the formula (16) by the formula (17) and then performing an integration processing on the result of the division by the integrator.
    In summary, in the fiber optic distributed sensor monitoring system 1 proposed by the embodiments of the present invention, the Rayleigh backscatter light carrying the detected signal is divided by the optical beam splitter 40 into the first beam. light and the second light beam, and the first light beam and the second light beam are processed by the first polarization controller 51 and the second polarization controller 52 into the first linearly polarized light and the second linearly polarized light, respectively , the directions of polarization of the first linearly polarized light and the second linearly polarized light being in a predetermined relationship. Interference modulation is performed on the first linearly polarized light and the second linearly polarized light by the first interference modulation device 61 and by the second interference modulation device 62, respectively, and then the first signal interference delivered by the first interference modulation device 61 and the second interference signal delivered by the second interference modulation device 62 are demodulated by the demodulation device 70 to obtain a corresponding detected signal. Therefore, it can be guaranteed as much as possible that the detected signal will not be lost, and that the signal-to-noise ratio of the fiber optic distributed sensor monitoring system will be effectively improved.
    The foregoing simply consists of specific implementations of the present invention, while the scope of protection of the present invention is not limited thereto. Variants or substitutions, which could easily be contemplated by a person skilled in the art who is familiar with the technical field in the technical scope presented by the present invention, should all fall within the scope of protection of the present invention. Thus, the scope of protection of the present invention should be confined by the scope of protection of the claims.
    权利要求:
    Claims (10)
    [1" id="c-fr-0001]
    1. Surveillance system with distributed fiber optic sensor, characterized in that it comprises a signal light generation device, a first optical coupler, a detection optical fiber, an optical beam splitter, a first polarization controller , a second polarization controller, a first interference modulation device, a second interference modulation device and a demodulation device, wherein the detection optical fiber is configured to detect a detected signal;
    the signal light generated by the signal light generating device is entered, via the first optical coupler, into the detection optical fiber;
    Rayleigh backscatter light carrying the detected signal, in the detection optical fiber, is returned to the first optical coupler, and is entered into the optical beam splitter through the first optical coupler, and is then divided into a first light beam and a second light beam by the optical beam splitter, the first light beam is processed by the first polarization controller to become a first linearly polarized light which then strikes the first interference modulation device, and the second light beam is processed by the second polarization controller to become a second linearly polarized light which also then strikes the second device which modulates directions of interference, in polarization of the first linearly polarized light and the second light linearly polarized so nt in a predetermined relationship; and the demodulation device is configured to demodulate a first interference signal supplied by the first interference modulating device and a second interference signal delivered by the second interference modulating device, to obtain the detected signal.
    [2" id="c-fr-0002]
    2. Surveillance system with distributed fiber optic sensor according to claim 1, characterized in that each of the first polarization controller and of the second polarization controller is a polarization controller of the fiber optic coil type, the polarization controller of the optical fiber coil type comprising an optical fiber coil wound on an outer wall of a tubular piezoelectric ceramic;
    wherein an input end of the optical fiber coil of the first polarization controller is coupled to a first beam splitting end of the optical beam splitter, and an output end of the optical fiber coil of the first polarization controller is coupled to the demodulation device, an input end of the optical fiber coil of the second polarization controller is coupled to a second optical beam splitting end of the optical beam splitter, and an output end of the fiber coil optics of the second polarization controller is coupled to the demodulation device; and the system further comprises a voltage output device, and each of the tubular piezoelectric ceramic of the first polarization controller, the tubular piezoelectric ceramic of the second polarization controller and the demodulation device is electrically connected to the voltage output device .
    [3" id="c-fr-0003]
    3. Monitoring system with distributed fiber optic sensor according to claim 2, characterized in that the fiber optic coil is a fiber optic coil of λ / 4.
    [4" id="c-fr-0004]
    4. Surveillance system with distributed fiber optic sensor according to claim 3, characterized in that the polarization controller of the fiber optic coil type further comprises a first housing, in which the fiber optic coil wound on the external wall tubular piezoelectric ceramic is packaged inside the first housing.
    [5" id="c-fr-0005]
    5. Monitoring system with distributed fiber optic sensor according to claim 4, characterized in that the polarization controller of the fiber optic coil type further comprises a motor and a transmission shaft, in which a rotary motor shaft is connected to the transmission shaft, the motor is connected, via the transmission shaft, to a rotation fitting arranged at a lower part of the first housing, and the motor of the first polarization controller and the motor of the second polarization controller are both electrically connected to the voltage output device;
    the motor of the first polarization controller is configured to rotate the optical fiber coil of the first polarization controller, to allow the optical fiber coil to deliver the first linearly polarized light; and the motor of the second polarization controller is configured to rotate the optical fiber coil of the second polarization controller, to allow the optical fiber coil to deliver the second linearly polarized light.
    [6" id="c-fr-0006]
    6. Distributed fiber optic sensor monitoring system according to claim 5, characterized in that the polarization controller of the fiber optic coil type further comprises a second housing, in which the first housing, in which the fiber coil optic wound on the outer wall of the tubular piezoelectric ceramic is conditioned, is arranged inside the second housing, and the second housing is provided with a first opening, a second opening and a third opening, the first opening being configured to allow input from the propeller shaft, the second opening being configured to allow output of a coil input from the fiber optic coil, and the third opening being configured to allow output of a coil output from the fiber optic coil.
    [7" id="c-fr-0007]
    7. Surveillance system with distributed fiber optic sensor according to claim 1, characterized in that the polarization directions of the first linearly polarized light and of the second linearly polarized light are orthogonal to one another.
    [8" id="c-fr-0008]
    8. Surveillance system with distributed fiber optic sensor according to any one of claims 1 to 7, characterized in that the first interference modulation device comprises a first fiber optic interferometer, the second interference modulation device includes a second fiber optic interferometer, and the demodulation device includes a first polarization beam combiner, a first photoelectric detector and a data processor, wherein an input end of the first fiber optic interferometer is coupled to one end output of the first polarization controller, an input end of the second fiber optic interferometer is coupled to an output end of the second polarization controller, an output end of the first fiber optic interferometer and an output end of the second interferometer fiber optics are all two coupled to an input end of the first polarized beam combiner, an output end of the first polarized beam combiner is coupled to an input end of the first photoelectric detector, and an output end of the first photoelectric detector is electrically connected to the data processor; and the first linearly polarized light between, and forms the first interference signal after undergoing interference processing applied by the first fiber optic interferometer, and the second linearly polarized light forms the second interference signal after having undergone interference processing applied by the second fiber optic interferometer, in which the first interference signal and the second interference signal both enter the first polarization beam combiner, and are converted, after being combined by the first polarization beam combiner, into an electrical signal by the first photoelectric detector, and then enter the data processor, and the data processor is configured to process the electrical signal to obtain the detected signal.
    [9" id="c-fr-0009]
    9. Surveillance system with distributed fiber optic sensor according to claim 8, characterized in that the first interference modulation device further comprises a second optical coupler, the second interference modulation device further comprises a third coupler optical, the demodulation device further comprises a second polarization beam combiner, a third polarization beam combiner, a second photoelectric detector and a third photoelectric detector, the first fiber optic interferometer comprises a first 3x3 coupler, and the second fiber optic interferometer includes a second 3x3 coupler;
    the output end of the first polarization controller is coupled to a first port of the second optical coupler, a second port of the second optical coupler is coupled to a first port of the first 3x3 coupler, a third port of the second optical coupler is coupled to the input end of the first polarized beam combiner, a second port of the first 3x3 coupler is coupled to an input end of the second polarized beam combiner, and a third port of the first 3x3 coupler is coupled to an end of input of the third polarization beam combiner;
    the output end of the second polarization controller is coupled to a first port of the third optical coupler, a second port of the third optical coupler is coupled to a first port of the second 3x3 coupler, a third port of the third optical coupler is coupled to the input end of the first polarized beam combiner, a second port of the second 3x3 coupler is coupled to the input end of the second polarized beam combiner, and a third port of the second 3x3 coupler is coupled to the input end of the third polarized beam combiner; and an output end of the second polarized beam combiner is coupled to an input end of the second photoelectric detector, an output end of the third polarized beam combiner is coupled to an input end of the third photoelectric detector, and an output end of the second photoelectric detector and an output end of the third photoelectric detector are both electrically connected to the data processor.
    [10" id="c-fr-0010]
    10. Distributed fiber optic sensor monitoring system according to claim 9, characterized in that each of the first fiber optic interferometer and the second fiber optic interferometer is a Michelson fiber optic interferometer.
    1/5
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    EP1387997A1|2004-02-11|Device for measuring a non-reciprocal effect, in particular fibre-optic gyro
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    同族专利:
    公开号 | 公开日
    FR3059776B1|2019-05-17|
    CN106525362A|2017-03-22|
    CN106525362B|2019-07-26|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    CN101639379A|2009-08-26|2010-02-03|南京大学|Vibration monitoring structure and method based on optical fiber polarized light time domain reflection sense|
    US20140176937A1|2011-08-18|2014-06-26|Tiegen Liu|Distributed disturbance sensing device and the related demodulation method based on polarization sensitive optical frequency domain reflectometry|
    CN105258745A|2015-11-09|2016-01-20|山东省科学院激光研究所|Downhole optical fiber distributed flow monitoring system|
    KR100282775B1|1998-02-21|2001-03-02|서원석|Optical fiber polarization scrambler and its driving parameter input method|
    US9146151B2|2010-11-18|2015-09-29|Optasense, Inc.|Pulse labeling for high-bandwidth fiber-optic distributed acoustic sensing with reduced cross-talk|
    CN102809421A|2011-06-01|2012-12-05|电子科技大学|Multi-point localizable distribution-type optical-fiber vibration sensor based on polarization-state differential detection|
    CN103411660B|2013-08-29|2014-12-03|山东省科学院激光研究所|Optical fiber distributed type sound wave monitor system|
    CN103487133B|2013-09-23|2015-08-19|安徽大学|Improve method and the device of the micro-vibration sensing system signal to noise ratio of laser|
    CN104596632A|2013-10-31|2015-05-06|上海华魏光纤传感技术有限公司|Distributed optical fiber vibration sensor for enhancing long-distance detection, and method of distributed optical fiber vibration sensor|
    CN206292019U|2016-12-02|2017-06-30|山东省科学院激光研究所|Distributed fiber-optic sensor monitoring system|CN108519219B|2018-04-18|2020-09-04|中山水木光华电子信息科技有限公司|System for self-adaptively identifying optical fiber codes in distance|
    CN108692807A|2018-04-27|2018-10-23|吉林大学|A kind of optical fiber distributed type acoustic monitoring system|
    CN108981767B|2018-08-17|2020-10-16|山东省科学院激光研究所|Optical fiber distributed monitoring system and method|
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    优先权:
    申请号 | 申请日 | 专利标题
    CN201611101079.2A|CN106525362B|2016-12-02|2016-12-02|Distributed fiber-optic sensor monitors system|
    CN201611101079.2|2016-12-02|
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