CN113465640A - Optical fiber temperature and pressure sensing system based on chirped pulses - Google Patents
Optical fiber temperature and pressure sensing system based on chirped pulses Download PDFInfo
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- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
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- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/35338—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using other arrangements than interferometer arrangements
- G01D5/35354—Sensor working in reflection
- G01D5/35358—Sensor working in reflection using backscattering to detect the measured quantity
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Abstract
The present disclosure provides a chirped pulse-based fiber temperature and pressure sensing system, comprising: the light source module (A) is used for generating excitation light and local oscillation light; the signal modulation module (B) is used for modulating the excitation light into linear chirped pulse light and amplifying the linear chirped pulse light to form detection light; the sensor module (C) is used for detecting by utilizing the detection light and returning the detection light carrying the sensing information; the signal detection module (D) is used for carrying out coherent processing on the detection light and the local oscillator light to obtain a phase-sensitive optical time domain reflectometer detection signal; and the signal demodulation module (E) is used for demodulating the detection signal to obtain a detection result. Wherein. The sensor module (C) adopts a chain-type structure quasi-distributed optical fiber sensor formed by a tubular optical fiber packaging technology. The system can realize the simultaneous measurement of high-resolution temperature and pressure, solve the problem of temperature-pressure crosstalk and improve the accuracy of the measurement result of the sensing system.
Description
Technical Field
The disclosure relates to the technical field of distributed optical fiber sensing, in particular to an optical fiber temperature and pressure sensing system based on chirped pulses.
Background
The existing chirp pulse direct detection based phase sensitive optical time domain reflectometry (CP-phi OTDR) system uses linear chirp pulses as detection pulses, performs equivalent compensation on phase change caused by external disturbance through frequency difference values corresponding to time delay differences of a Rayleigh backscattering spectrum of the chirp pulses before and after disturbance, and finally realizes quantitative measurement on temperature and strain because the phase change and the disturbance amount are in a linear relation, and the measurement resolution is as high as 1mK/4n epsilon and is about two orders of magnitude higher than that of the existing distributed sensing system based on a Raman scattering effect and a Brillouin scattering effect, so that the system has extremely important significance for high-resolution static sensing fields such as crustal deformation observation, geothermal observation and ocean temperature and depth sensing in seismology.
However, the measurement response (i.e. the time delay difference of the rayleigh backscatter spectra of the chirped pulses before and after disturbance) of the chirped pulse direct detection type phase-sensitive optical time domain reflection system is affected by both temperature and strain, so that the system has temperature-strain cross sensitivity, and because the strain of the optical fiber is in direct proportion to the magnitude of the stress, the simultaneous measurement of both temperature and stress parameters is difficult. In practical application, temperature and stress usually occur simultaneously, so that crosstalk between temperature and stress of the system is large in high-resolution measurement scenes such as geophysical scenes, ocean temperature depth scenes and the like, accurate measurement results are difficult to obtain, and development of the system in the field of detecting high-resolution temperature and stress change is restricted due to the defect.
BRIEF SUMMARY OF THE PRESENT DISCLOSURE
Based on this, the present disclosure provides a chirped pulse-based fiber optic temperature and pressure sensing system comprising: the light source module A is used for generating excitation light and local oscillation light; the signal modulation module B is used for modulating the excitation light into linear chirped pulse light and amplifying the linear chirped pulse light to form detection light; the sensor module C is used for detecting by utilizing the detection light and returning the detection light carrying the sensing information; the signal detection module D is used for carrying out coherent processing on the detection light and the local oscillator light to obtain a detection signal of the phase-sensitive optical time domain reflectometer; and the signal demodulation module E is used for demodulating the detection signal to obtain a detection result.
According to an embodiment of the present disclosure, wherein, the light source module a includes: a narrow linewidth laser 1 for outputting continuous light of a fixed frequency; the input end of the optical isolator 2 is connected with the output end of the narrow-linewidth laser 1 and used for limiting the transmission direction of continuous light; and the input end of the coupler 3 is connected with the output end of the optical isolator 2 and is used for splitting the continuous light into excitation light and local oscillation light.
According to the embodiment of the present disclosure, the signal modulation module B includes: a frequency modulator 4 for modulating the excitation light into linearly chirped light; a pulse modulator 5 for modulating the linearly chirped light into a linearly chirped pulsed light; and the erbium-doped fiber amplifier 7 is used for amplifying the optical power of the linear chirped pulse light to form detection light.
According to the embodiment of the present disclosure, the sensor module C adopts a chain-structured quasi-distributed optical fiber sensor 9 constructed by a tube-type optical fiber package technology.
According to the embodiment of the present disclosure, the quasi-distributed optical fiber sensor 9 with a chain structure includes two hollow cylinders 91 made of an elastic base material, the inside of one hollow cylinder 91 is of a closed structure, the inside of the other hollow cylinder 91 is of a non-closed structure, and the sensing optical fibers 92 are respectively wound outside the two hollow cylinders 91; the two hollow cylinders 91 are adjacently placed so that the two hollow cylinders 91 are in the same temperature and pressure state.
According to the embodiment of the present disclosure, wherein the signal detection module D includes: the polarization diversity coherent receiver 10 is configured to perform coherent reception on the detection light after amplification and filtering processing, and perform coherent reception on the detection light and two polarization states of the local oscillator light, respectively, to obtain a phase-sensitive optical time domain reflectometer detection signal.
According to the embodiment of the present disclosure, wherein the signal detection module D includes: the data acquisition card 11 is used for acquiring detection signals of the phase-sensitive optical time domain reflectometer; and the signal processor 12 is used for demodulating and processing the detection signal of the phase-sensitive optical time domain reflectometer to obtain a temperature value and a pressure value to be measured.
According to an embodiment of the present disclosure, the optical fiber temperature pressure sensing system further comprises: the circulator 8 includes a first port a, a second port B, and a third port C, where the first port a is connected to the output port of the signal modulation module B to receive the detection light, the second port B is connected to the sensor module C to input the detection light to the sensor module C and receive the detection light returned by the sensor module C, and the third port C is connected to the input end of the signal detection module D to input the detection light to the signal detection module D.
According to an embodiment of the present disclosure, the optical fiber temperature pressure sensing system further comprises: and the signal generator 6 comprises a first output port, a second output port and a third output port, and is respectively connected with the frequency modulator 4, the pulse modulator 5 and the electrical input end of the data acquisition card 11 so as to drive the frequency modulator 4, the pulse modulator 5 and the data acquisition card 11 to work.
According to the embodiment of the present disclosure, wherein the frequency modulator 4 adopts an IQ electro-optical modulator, and the pulse modulator 5 adopts an acousto-optical modulator; the signal generator 6 loads two voltage signals with a phase difference of pi/2 to drive the IQ electro-optic modulator, and the signal generator 6 loads a pulse voltage signal to drive the acousto-optic modulator.
Drawings
The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure with reference to the accompanying drawings, in which:
fig. 1 schematically illustrates a block diagram of a chirped pulse-based high-resolution fiber optic temperature and pressure sensing system provided by an embodiment of the present disclosure.
Fig. 2 schematically illustrates a package structure diagram of a sensor module provided in an embodiment of the present disclosure.
[ reference numerals ]
The device comprises an A-light source module, a B-signal modulation module, a C-sensor module, a D-signal detection module and an E-signal demodulation module;
the system comprises a 1-narrow line width laser, a 2-optical isolator, a 3-coupler, a 4-frequency modulator, a 5-pulse modulator, a 6-signal generator, a 7-erbium-doped fiber amplifier, an 8-circulator, a 9-chain-structure quasi-distributed fiber sensor, a 91-hollow cylinder, a 92-sensing fiber, a 10-polarization diversity coherent receiver, an 11-data acquisition card and a 12-signal processor.
Detailed Description
For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings. It is to be understood that the described embodiments are only a few, and not all, of the disclosed embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
In the present disclosure, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integral; can be mechanically connected, electrically connected or can communicate with each other; either directly or indirectly through intervening media, either internally or in any other suitable relationship. The specific meaning of the above terms in the present disclosure can be understood by those of ordinary skill in the art as appropriate.
In the description of the present disclosure, it is to be understood that the terms "longitudinal," "length," "circumferential," "front," "rear," "left," "right," "top," "bottom," "inner," "outer," and the like are used in the orientation or positional relationship indicated in the drawings for convenience in describing the present disclosure and for simplicity in description, and are not intended to indicate or imply that the referenced subsystems or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present disclosure.
Throughout the drawings, like elements are represented by like or similar reference numerals. Conventional structures or constructions will be omitted when they may obscure the understanding of the present disclosure. And the shapes, sizes and positional relationships of the components in the drawings do not reflect the actual sizes, proportions and actual positional relationships. Furthermore, in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.
Similarly, in the above description of exemplary embodiments of the disclosure, various features of the disclosure are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various disclosed aspects. Reference to the description of the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the disclosure. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present disclosure, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specifically limited otherwise.
An object of the embodiments of the present disclosure is to provide a chirped pulse-based optical fiber temperature and pressure sensing system, which uses a chirped pulse phase-sensitive optical time domain reflectometer (CP-medium OTDR) as a basis, and adopts a coherent detection and external modulation linear chirped pulse mode to improve the measurement performance of the sensing system. The sensor adopts two adjacent sections of optical fibers to be respectively wound in an elastic base material hollow cylinder, one inner part of each base material hollow cylinder is of a closed structure, the other inner part of each base material hollow cylinder is of a non-closed structure and is placed close to each other so as to be in the same temperature and pressure state, the sensor obtains different temperature and pressure response characteristics, a binary primary equation set related to the temperature and the pressure is established according to the two temperature and pressure response characteristics, and the temperature and the pressure of each sensing point are obtained by solving the equation set. And further, the simultaneous measurement of high-resolution temperature and pressure can be realized, the problem of temperature-pressure crosstalk can be solved, and the accuracy of the measurement result of the sensing system is improved. The following detailed description is made with reference to the accompanying drawings.
Fig. 1 schematically illustrates a block diagram of a chirped pulse-based high-resolution fiber optic temperature and pressure sensing system provided by an embodiment of the present disclosure.
As shown in fig. 1, the system may include, for example, a light source module a, a signal modulation module B, a sensor module C, a signal detection module D, and a signal demodulation module E.
The light source module A is used for generating excitation light and local oscillation light.
In an embodiment of the present disclosure, the light source module a may include, for example, a narrow linewidth laser 1, an optical isolator 2, and a coupler 3. The output end of the narrow linewidth laser 1 is connected with the input end of the optical isolator 2, and the output end of the optical isolator 2 is connected with the input end of the coupler 3. The narrow linewidth laser 1 is used to output continuous light of a fixed frequency. The optical isolator 2 is used to define the transmission direction of the continuous light output by the narrow linewidth laser 1, i.e. the light can only be transmitted from the narrow linewidth laser 1 to the coupler 3. The coupler 3 is configured to split the continuous light with the fixed frequency into excitation light and local oscillation light, and the coupler 3 includes two output ports, where a first output port is configured to output the excitation light and a second output port is configured to output the local oscillation light.
The signal modulation module B is used for modulating the excitation light into linear chirped pulse light and amplifying the linear chirped pulse light to form detection light.
In an embodiment of the present disclosure, the signal modulation module B may include, for example, a frequency modulator 4, a pulse modulator 5, and an erbium-doped fiber amplifier 7. An input end of the frequency modulator 4 is connected to a first output port of the coupler 3, and is used for modulating the received excitation light into linearly chirped light. An input end of the pulse modulator 5 is connected to an output end of the frequency modulator 4, and is configured to modulate the linearly chirped light into linearly chirped pulsed light. The input end of the erbium-doped fiber amplifier 7 is connected with the output end of the pulse modulator 5 and is used for amplifying the optical power of the linear chirped pulse light to form detection light.
The sensor module C is configured to detect by using the probe light and return the detection light carrying the sensing information.
In an embodiment of the present disclosure, the sensor module C employs a quasi-distributed optical fiber sensor 9 with a chain structure formed by a tube-type optical fiber package technology.
Fig. 2 schematically illustrates a package structure diagram of a sensor module provided in an embodiment of the present disclosure.
As shown in fig. 2, the quasi-distributed optical fiber sensor 9 with a chain structure includes two hollow cylinders 91 made of elastic base material, one of the hollow cylinders 91 has a sealed structure, the other hollow cylinder 91 has a non-sealed structure, and the hollow cylinders are communicated with the outside atmosphere through vent holes with diameters of upper and lower bottoms. The two hollow cylinders 91 are connected by respectively winding the sensing optical fibers 92 outside the two hollow cylinders 91, and the two hollow cylinders 91 are adjacently arranged so that the two hollow cylinders are in the same temperature and pressure state, and the sensor obtains different temperature and pressure response characteristics. In a specific example, the diameter of the hollow cylinder 91 is 100mm, the length is 100mm, the wall thickness is 5mm, the thickness of the upper bottom and the lower bottom are 10mm, the outer wall surface of the 80mm part in the middle of the cylinder is provided with a spiral groove, the diameter of the spiral groove is 1.5mm, the number of turns is 32, the spiral groove is used for winding the sensing optical fiber 92, and the diameter of the bottom vent hole is 5 mm.
And the signal detection module D is used for carrying out coherent processing on the detection light and the local oscillator light to obtain a detection signal of the phase-sensitive optical time domain reflectometer.
In an embodiment of the present disclosure, the signal detection module D may include: the polarization diversity coherent receiver 10 is configured to perform coherent reception on the detection light after amplification and filtering processing, and perform coherent reception on the detection light and two polarization states of the local oscillator light, respectively, to obtain a phase-sensitive optical time domain reflectometer detection signal. Specifically, the polarization diversity coherent receiver 10 includes two input ports and two output ports, wherein a first input port of the polarization diversity coherent receiver 10 is connected to a second output port of the coupler 3 to receive the local oscillator light, and a second input port of the polarization diversity coherent receiver 10 is used to receive the detected light with the sensing information returned by the sensor module D.
And the signal demodulation module E is used for demodulating the detection signal to obtain a detection result.
In an embodiment of the present disclosure, the signal demodulation module E may include, for example, a data acquisition card 11 and a signal processor 12. The data acquisition card 11 includes two input ports, a first input port of which is connected to a first output port of the polarization diversity coherent receiver 10, a second input port of which is connected to a second output port of the polarization diversity coherent receiver 10, and the two input ports are respectively used for acquiring phase-sensitive optical time domain reflectometer detection signals obtained by respectively performing coherent reception on two polarization states of detection light and local oscillator light. An output port of the data acquisition card 11 is connected to an input port of the signal processor 12, and is configured to input the acquired detection signal of the phase-sensitive optical time domain reflectometer into the signal processor 12, so that the signal processor 12 demodulates and processes the detection signal of the phase-sensitive optical time domain reflectometer to obtain a temperature value to be measured and a pressure value.
Further, in order to enable better transmission of the detection light and the detection light, the fiber temperature and pressure sensing system based on chirped pulses may further include a circulator 8, where the circulator 8 includes a first port a, a second port B, and a third port C, where the first port a is connected to the output port of the signal modulation module B (i.e., connected to the output end of the erbium-doped fiber amplifier 7) to receive the detection light, the second port B is connected to the sensor module C to input the detection light to the sensor module C and receive the detection light returned by the sensor module C, and the third port C is connected to the input end of the signal detection module D (i.e., connected to the second input port of the polarization diversity coherent receiver 10) to input the detection light to the signal detection module D.
Furthermore, the optical fiber temperature and pressure sensing system based on chirped pulses may further include a signal generator 6, where the signal generator 6 includes a first output port, a second output port, and a third output port, and is respectively connected to the frequency modulator 4, the pulse modulator 5, and the electrical input end of the data acquisition card 11, so as to drive the frequency modulator 4, the pulse modulator 5, and the data acquisition card 11 to operate.
To more clearly illustrate the fiber optic temperature and pressure sensing system provided by the present disclosure, a detailed description is provided below with respect to one specific example.
Specifically, the narrow linewidth tunable laser 1 adopts a narrow linewidth semiconductor laser, the linewidth of output laser is less than 2kHz, the wavelength is 1550.12nm, and the output laser is divided into two paths through a coupler 3. One path of the light enters the polarization diversity coherent receiver 10 as local oscillation light, the other path of the light enters the signal modulation module, periodic repeated linear chirped pulse light is generated through the frequency modulator 4 and the pulse modulator 5, the frequency modulator 4 adopts an IQ electro-optic modulator, linear frequency sweep voltage signals with continuous phases are loaded through the signal generator 6, for the IQ electro-optic modulator, two paths of voltage signals with a phase difference of pi/2, namely I, Q signals, need to be loaded, I, Q signals can be generated through two output ports of the signal generator 6 or through a 90-degree electric bridge, the pulse modulator 5 adopts an acousto-optic modulator, and pulse voltage signals are loaded through the signal generator 6. In order to ensure that there is no aliasing problem of the back rayleigh scattered light in the sensing fiber, only one optical pulse is allowed to exist in the sensing fiber at a time, so the maximum pulse repetition frequency is inversely proportional to the length of the transmission fiber. Maximum repetition frequency f of pulsesmaxAnd the length L of the transmission fibertotThe relationship is fmax＝c/(2neffLtot) Where c is the speed of light in vacuum, neffIs the effective refractive index of the sensing fiber.
The working principle of the chirped pulse-based high-resolution fiber temperature and pressure sensing system is briefly described as follows:
narrow linewidth laser 1 produces the laser and divides into excitation light and local oscillator light through coupler 3 to with excitation light input to signal modulation module B, with local oscillator light input to signal detection module D, the expression of local oscillator light is:
wherein E isL0Amplitude of the local oscillator light, v0For the frequency of the output laser light of the narrow linewidth laser 1,
is the initial phase of the local oscillator light.
The excitation light is input to a frequency modulator 4, the frequency modulator 4 adopts an IQ electro-optic modulator, and a bias voltage controller is adopted to control the bias voltage of the IQ electro-optic modulator, so that the carrier suppression single sideband modulation function of the IQ modulator is realized, and at the moment, the transfer function of the IQ electro-optic modulator is as follows:
wherein, VπIs the half-wave voltage of the IQ electro-optical modulator.
Two paths of I, Q driving voltages required by an IQ electro-optical modulator are generated by a signal generator 6, an arcsine pre-distortion method is adopted, and the expression of I, Q two paths of driving voltages is as follows:
wherein, VDIs the amplitude factor, vmAs the initial frequency, γ ═ B/tmIs the chirp slope, B is the chirp frequency range, tmIs the chirp time.
The expression of the exciting light passing through the frequency modulator 4, the pulse modulator 5 and the erbium-doped fiber amplifier 7 to generate the detection light is as follows:
wherein E isS0To detect the amplitude of the light, tpIn order to be the pulse width of the pulse,
for detecting the initial phase of lightA bit.
The probe light is injected into the sensor module C through the circulator 8 to form backscatter detection light, and the expression is:
wherein E isR0Detecting the amplitude of light for backscattering
Is the time delay of the backscattered light from the ith scattering point, ziIs the length of the sensing fiber from the input end to the ith scattering point, N is the total number of scattering points, and alpha is the attenuation constant of the sensing fiber.
The backscatter detection light and the local oscillator light are respectively coherently received in two polarization states in the polarization diversity coherent receiver 10 to obtain a detection signal, the two polarization states are in an orthogonal polarization relationship, and by transmitting the two polarization states and performing root mean square and superposition processing on each path of signal, the polarization fading noise is reduced, and the direct current component in the detection signal is ignored, which can be expressed as:
where R is the responsivity of the balanced photodetector in the polarization diversity coherent receiver 10.
Neglect of phiij，1And
all the small items in (1) include:
wherein, the delta epsilon is the strain change quantity of the sensing optical fiber,
is the effective elastic-optical coefficient, p, of the sensing fiberijThe elastic tensor component of the sensing optical fiber is sigma, the Poisson ratio coefficient of the sensing optical fiber is alpha, the thermal expansion coefficient of the sensing optical fiber is alpha, the temperature change quantity is delta T, the frequency change quantity is delta v, and the time delay of the detection signal spectrum before and after the change is delta T.
When sensing optical fiber twines in the hollow cylinder of elasticity base material, the thermal expansion of the hollow cylinder of elasticity base material produces deformation with receiving pressure, to the fine effect of sensing light, has:
wherein, Delta F is the pressure change quantity of the hollow cylinder of the elastic base material, and SigmamIs the Poisson ratio of the hollow cylinder of the elastic base material, E is the elastic modulus of the hollow cylinder of the elastic base material, Delta T is the temperature change quantity, and alphamIs the thermal expansion coefficient of the hollow cylinder of the elastic base material.
The elastic base material hollow cylinder adopts two structures of a closed structure and an unsealed structure, and the elastic modulus of the elastic base material hollow cylinder can be greatly different, so that the time delay delta t of a detection signal spectrum is measured under the elastic base material hollow cylinders with the two structures1And Δ t2By utilizing the characteristic that the respective time delay is in linear relation with the temperature and the pressure, the following linear equation system of two elements is established:
Δt1＝CT1δT+CF1δF
Δt2＝CT2δT+CF2δF
where δ T is the temperature variation, δ F is the pressure variation, CT1And CT2Respectively a hollow cylinder made of two structural elastic base materialsCoefficient of temperature variation of CF1And CF2The pressure coefficients of the two structural elastic substrate materials under the hollow column are respectively solved, the equation set is solved, the temperature variation and the pressure variation can be obtained, and then the temperature and the pressure are demodulated.
In the system, an optical attenuator can be added at any position in the optical path to adjust the optical power, and a radio frequency attenuator can be added between radio frequency components to adjust the radio frequency signal power.
The optical fiber temperature and pressure sensing system based on the chirped pulse provided by the embodiment of the disclosure is based on chirped pulse phase-sensitive optical time domain reflectometry, and improves the measurement performance of the sensing system by adopting a coherent detection and external modulation linear chirped pulse mode. The quasi-distributed optical fiber sensor with the chain structure is formed by adopting a tubular optical fiber packaging technology. The sensor adopts two adjacent sections of optical fibers to be respectively wound in an elastic base material hollow cylinder, one inner part of the two base material hollow cylinders is of a closed structure, the other inner part of the two base material hollow cylinders is of a non-closed structure and is closely arranged to be in the same temperature and pressure state, so that the sensor obtains different temperature and pressure response characteristics, a two-dimensional linear equation set related to temperature and pressure is established according to the two temperature and pressure response characteristics, the temperature and pressure of each sensing point are obtained by solving the equation set, further, the simultaneous measurement of high-resolution temperature and pressure can be realized, the temperature-pressure crosstalk problem can be solved, and the accuracy of the measurement result of a sensing system is improved.
The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.
Claims (10)
1. A chirped pulse-based fiber optic temperature and pressure sensing system, comprising:
the light source module (A) is used for generating excitation light and local oscillation light;
the signal modulation module (B) is used for modulating the excitation light into linear chirped pulse light and amplifying the linear chirped pulse light to form detection light;
the sensor module (C) is used for detecting by utilizing the detection light and returning detection light carrying sensing information;
the signal detection module (D) is used for carrying out coherent processing on the detection light and the local oscillator light to obtain a phase-sensitive optical time domain reflectometer detection signal;
and the signal demodulation module (E) is used for demodulating the detection signal to obtain a detection result.
2. The fiber optic temperature and pressure sensing system of claim 1, wherein the light source module (a) comprises:
a narrow linewidth laser (1) for outputting continuous light of a fixed frequency;
an input end of the optical isolator (2) is connected with an output end of the narrow linewidth laser (1) and used for limiting the transmission direction of the continuous light;
the input end of the coupler (3) is connected with the output end of the optical isolator (2) and used for splitting the continuous light into the excitation light and the local oscillator light.
3. The fiber optic temperature and pressure sensing system of claim 1, wherein the signal modulation module (B) comprises:
a frequency modulator (4) for modulating the excitation light into linearly chirped light;
a pulse modulator (5) for modulating the linearly chirped light into linearly chirped pulsed light;
and the erbium-doped fiber amplifier (7) is used for amplifying the optical power of the linearly chirped pulse light to form the detection light.
4. The fiber optic temperature and pressure sensing system of claim 1, wherein the sensor module (C) employs a quasi-distributed fiber optic sensor (9) of a chain structure constructed by tube-type fiber optic packaging technology.
5. The optical fiber temperature and pressure sensing system according to claim 4, wherein the chain-structured quasi-distributed optical fiber sensor (9) comprises two hollow cylinders (91) made of elastic base materials, the inside of one hollow cylinder (91) is of a closed structure, the inside of the other hollow cylinder (91) is of a non-closed structure, and the sensing optical fiber (92) is respectively wound outside the two hollow cylinders (91); the two hollow columns are adjacently placed so that the two hollow columns (91) are in the same temperature and pressure state.
6. The fiber optic temperature and pressure sensing system of claim 3, wherein the signal detection module (D) comprises:
and the polarization diversity coherent receiver (10) is used for amplifying and filtering the detection light, and then respectively carrying out coherent reception on the detection light and two polarization states of the local oscillator light to obtain the phase-sensitive optical time domain reflectometer detection signal.
7. The fiber optic temperature and pressure sensing system of claim 1, wherein the signal detection module (D) comprises:
the data acquisition card (11) is used for acquiring detection signals of the phase-sensitive optical time domain reflectometer;
and the signal processor (12) is used for demodulating and processing the detection signal of the phase-sensitive optical time domain reflectometer to obtain a temperature value and a pressure value to be detected.
8. The fiber optic temperature and pressure sensing system of claim 1, further comprising:
a circulator (8) comprising a first port (a), a second port (B) and a third port (C), wherein the first port (a) is connected to the output port of the signal modulation module (B) to receive the detection light, the second port (B) is connected to the sensor module (C) to input the detection light to the sensor module (C) and receive the detection light returned by the sensor module (C), and the third port (C) is connected to the input end of the signal detection module (D) to input the detection light to the signal detection module (D).
9. The fiber optic temperature and pressure sensing system of claim 6, further comprising:
and the signal generator (6) comprises a first output port, a second output port and a third output port, and is respectively connected with the frequency modulator (4), the pulse modulator (5) and the electrical input end of the data acquisition card (11) so as to drive the frequency modulator (4), the pulse modulator (5) and the data acquisition card (11) to work.
10. The fiber optic temperature and pressure sensing system according to claim 9, wherein said frequency modulator (4) employs an IQ electro-optic modulator, and said pulse modulator (5) employs an acousto-optic modulator;
the signal generator (6) loads two voltage signals with a pi/2 difference to drive the IQ electro-optic modulator, and the signal generator (6) loads a pulse voltage signal to drive the acousto-optic modulator.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20170153130A1 (en) * | 2015-12-01 | 2017-06-01 | Rhode Island Board Of Education, State Of Rhode Island And Providence Plantations | Digitally controlled chirped pulse laser for sub-terahertz range fiber structure interrogation |
| CN111854815A (en) * | 2020-08-05 | 2020-10-30 | 国网四川省电力公司经济技术研究院 | High-speed distributed optical fiber sensing system and method based on fractional Fourier transform |
| CN112985639A (en) * | 2021-02-06 | 2021-06-18 | 电子科技大学 | Distributed optical fiber sensing method based on chirp removal and time domain sub-chirp pulse extraction |
-
2021
- 2021-08-23 CN CN202110971302.3A patent/CN113465640B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20170153130A1 (en) * | 2015-12-01 | 2017-06-01 | Rhode Island Board Of Education, State Of Rhode Island And Providence Plantations | Digitally controlled chirped pulse laser for sub-terahertz range fiber structure interrogation |
| CN111854815A (en) * | 2020-08-05 | 2020-10-30 | 国网四川省电力公司经济技术研究院 | High-speed distributed optical fiber sensing system and method based on fractional Fourier transform |
| CN112985639A (en) * | 2021-02-06 | 2021-06-18 | 电子科技大学 | Distributed optical fiber sensing method based on chirp removal and time domain sub-chirp pulse extraction |
Non-Patent Citations (2)
| Title |
|---|
| J. PASTOR-GRAELLS等: "Single-shot distributed temperature and strain tracking using direct detection phase-sensitive OTDR with chirped pulses", UNIVERSITY OF ALCALA BIBLIOTECA, vol. 24, no. 12, pages 13121 - 13133 * |
| 钟翔;赵世松;邓华夏;张进;马孟超: "基于脉冲调制的Φ-OTDR 研究综述", 红外与激光工程, vol. 49, no. 10, pages 1 - 10 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114111712A (en) * | 2022-01-26 | 2022-03-01 | 天津风霖物联网科技有限公司 | System and method for monitoring building settlement |
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