Optical fiber multi-parameter sensing system and working method thereof

Abstract

The application belongs to the technical field of optical fiber communication, and aims to provide an optical fiber multi-parameter sensing system and a working method thereof.The optical fiber multi-parameter sensing system comprises a light source module, a communication optical cable, an optical fiber interference assembly, a sensing optical cable and a data processing assembly.The output end of the light source module and the input end of the data processing assembly are connected with the optical fiber interference assembly through the communication optical cable.The optical fiber interference assembly comprises a light processing front end unit and a light processing tail end unit connected with the communication optical cable in sequence.The light processing front end unit is connected with the light processing tail end unit through the sensing optical cable.The application can realize the synchronous monitoring of multiple physical parameters, and has low cost, low system complexity and simple deployment and maintenance.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fiber communication, and in particular relates to an optical fiber multi-parameter sensing system and a working method thereof. Background Art

[0002] Fiber optic sensing technology has been widely used in complex environmental monitoring scenarios due to its advantages such as resistance to electromagnetic interference, high sensitivity, and long-distance distributed monitoring. Its inherent safety, corrosion resistance, and high temperature resistance make it widely used in harsh environments such as chemical plants, nuclear power plants, and ocean monitoring. In addition, optical fiber is light and flexible, easy to embed into composite materials or small spaces, and has a long lifespan and low maintenance costs. It shows broad application prospects in fields such as energy, national defense, and infrastructure health monitoring.

[0003] Fiber optic sensors have the ability to integrate multiple parameters, enabling the simultaneous detection of physical quantities such as temperature, strain, and vibration. Currently, different technical solutions are typically used to monitor physical quantities in different frequency bands: low-frequency vibration monitoring is primarily based on distributed fiber optic acoustic sensing technology using time-domain reflectometry, while high-frequency signals typically use fiber interferometry techniques such as Mach-Zehnder interferometers. Continuous distributed measurements of parameters such as temperature and strain primarily rely on Brillouin optical time-domain reflectometry (OTDR) based on spontaneous Brillouin scattering (SBS) or Brillouin optical time-domain analysis (OTDA) based on stimulated Brillouin scattering (SBS).

[0004] However, in the process of using the existing technology, the inventors found that the existing technology has at least the following problems:

[0005] First, existing technologies utilize multiple discrete systems, requiring different technical solutions to monitor different parameters. This results in high system complexity and high costs. This is particularly true when monitoring multiple parameters, such as broadband vibration and stress and strain, requires simultaneous monitoring. Equipment cost becomes a major constraint to large-scale adoption. Second, existing technologies struggle to efficiently integrate the simultaneous monitoring of broadband vibration, stress and strain, and temperature within a single system. This lack of integration necessitates the deployment of multiple systems, increasing installation and maintenance challenges. Summary of the Invention

[0006] In order to solve the above technical problems at least to a certain extent, the present invention provides an optical fiber multi-parameter sensing system and a working method thereof.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present application discloses a kind of optical fiber multi-parameter sensing system, including light source module, communication cable, optical fiber interference component, sensing cable and data processing component, the output of the light source module and the input of the data processing component are connected with the optical fiber interference component by the communication cable, the optical fiber interference component includes optical processing front end unit and optical processing tail end unit connected with the communication cable in sequence, the optical processing front end unit is connected with the optical processing tail end unit by the sensing cable;

[0009] The light source module is used for phase-in modulation processing of laser, and transmitting the modulated laser carrier to the optical processing front end unit through the communication cable;

[0010] The optical processing front end unit is used for splitting the laser carrier into sensing light and reference light, and transmitting the sensing light to the optical processing tail end unit through the sensing cable;Wherein, the sensing cable is used for phase-out modulation processing of the light signal passing through it;

[0011] The optical processing tail end unit is used for reflection processing of the sensing light, and transmitting the reflected sensing light to the optical processing front end unit through the sensing cable;

[0012] The optical processing front end unit is also used for obtaining interference optical signal from the reflected sensing light and the reference light, and transmitting the interference optical signal to the data processing component through the communication cable;

[0013] The data processing component is used for analyzing and processing the interference optical signal to obtain multiple physical parameters.

[0014] In a possible design, the optical processing front end unit includes a 2x2 optical coupler and a 3x3 optical coupler, the communication cable includes a transmitting optical fiber and two receiving optical fibers, the first input end of the 2x2 optical coupler is connected with the output of the light source module through the transmitting optical fiber, for receiving the laser carrier output by the light source module, the first output end of the 2x2 optical coupler is connected with the sensing cable, the second input end and the second output end of the 2x2 optical coupler are respectively connected with any two input ends of the 3x3 optical coupler, and any two output ends of the 3x3 optical coupler are respectively connected with the input end of the data processing component through the two receiving optical fibers, for outputting interference optical signal to the data processing component through the two receiving optical fibers.

[0015] In a possible design, the optical processing front end unit further includes an isolator, and the transmitting optical fiber is connected with the first input end of the 2x2 optical coupler through the isolator.

[0016] In one possible design, the optical processing tail end unit includes a Faraday rotation mirror, which is connected to the sensing optical cable and is used to receive the sensing light transmitted by the sensing optical cable and perform reflection processing on it.

[0017] In one possible design, the data processing component includes a first light detector, a second light detector, a data acquisition card, and a signal processing unit. The first light detector and the second light detector are both connected to the communication optical cable to receive the interference light signal transmitted by the communication optical cable. The first light detector and the second light detector are both connected to the signal acquisition terminal of the data acquisition card, and the data acquisition card is connected to the signal processing unit.

[0018] The first light detector and the second light detector are respectively used to convert the two coherent light signals in the interference light signal into analog electrical signals and send them to the data acquisition card;

[0019] The data acquisition card is used to convert the two-way analog electrical signals into digital electrical signals and send the two-way digital electrical signals to the signal processing unit;

[0020] The signal processing unit is used to restore the two digital electrical signals into two analog electrical signals, and perform phase demodulation and phase analysis processing based on the two analog electrical signals to obtain multiple physical parameters.

[0021] In a second aspect, the present invention discloses a method for operating a fiber optic multi-parameter sensing system as described in any one of the above, comprising:

[0022] The light source module performs phase modulation processing on the laser and transmits the modulated laser carrier to the optical processing front-end unit through the communication optical cable;

[0023] The optical processing front-end unit splits the laser carrier into sensing light and reference light, and transmits the sensing light to the optical processing tail-end unit through the sensing optical cable; wherein the sensing optical cable is used to perform phase external modulation processing on the optical signal passing therethrough;

[0024] The optical processing tail end unit performs reflection processing on the sensing light and transmits the reflected sensing light to the optical processing front end unit through the sensing optical cable;

[0025] The optical processing front-end unit obtains an interference light signal based on the reflected sensing light and the reference light, and transmits the interference light signal to the data processing component through the communication optical cable;

[0026] The data processing component analyzes and processes the interference light signal to obtain a variety of physical parameters.

[0027] In one possible design, the data processing component includes a first light detector, a second light detector, a data acquisition card, and a signal processing unit. The first light detector and the second light detector are both connected to the communication optical cable to receive the interference light signal transmitted by the communication optical cable. The first light detector and the second light detector are both connected to the signal acquisition terminal of the data acquisition card, and the data acquisition card is connected to the signal processing unit. Correspondingly, the data processing component analyzes and processes the interference light signal to obtain multiple physical parameters, including:

[0028] The first photodetector and the second photodetector respectively convert the two coherent light signals in the interference light signal into analog electrical signals and send them to the data acquisition card;

[0029] The data acquisition card converts the two analog electrical signals into digital electrical signals, and sends the two digital electrical signals to the signal processing unit;

[0030] The signal processing unit restores the two digital electrical signals into two analog electrical signals, and performs phase demodulation and phase analysis processing according to the two analog electrical signals to obtain a variety of physical parameters.

[0031] In one possible design, the multiple physical parameters include temperature and stress and strain values; correspondingly, the signal processing unit performs phase demodulation and phase analysis processing on the two analog electrical signals to obtain the multiple physical parameters, including:

[0032] The signal processing unit performs phase demodulation processing on the two analog electrical signals to obtain an optical phase time-varying signal;

[0033] The signal processing unit performs Fourier transform processing on the optical phase time-varying signal to obtain a frequency spectrum and a phase spectrum, and extracts a frequency spectrum component consistent with the internal modulation frequency of the light source module from the frequency spectrum;

[0034] The signal processing unit obtains the optical path difference of the interference light signal according to the spectral components, and then obtains the temperature and stress-strain values ​​of the sensing optical cable according to the optical path difference.

[0035] In one possible design, the spectral components are:

[0036] ;

[0037] Among them, Δ φ ( t )for t The optical phase time-varying signal at time , FFT( ) represents the Fourier transform function, and max( ) represents the maximum value function.

[0038] In a possible design, the multiple physical parameters further include a vibration signal; correspondingly, after the signal processing unit extracts the spectral component consistent with the internal modulation frequency of the light source module from the spectrum, the method further includes:

[0039] The signal processing unit corrects the spectral component to obtain a corrected spectral component, and performs inverse Fourier transform on the corrected spectral component and the phase spectrum to obtain a vibration phase time-varying signal reflecting external vibration characteristics;

[0040] The signal processing unit demodulates the vibration phase time-varying signal to obtain a vibration signal.

[0041] The beneficial effects of the present application are mainly embodied in the realization of the synchronous monitoring of multiple physical parameters, low cost, low system complexity, and easy deployment and maintenance. Specifically, in the implementation process of the present application, the light source module performs internal phase modulation on the laser, and transmits the modulated laser carrier to the optical processing front-end unit through the communication optical cable; the optical processing front-end unit divides the laser carrier into sensing light and reference light, and transmits the sensing light to the optical processing tail-end unit through the sensing optical cable; the optical processing tail-end unit reflects the sensing light, and transmits the reflected sensing light to the optical processing front-end unit through the sensing optical cable; the optical processing front-end unit obtains an interference light signal according to the reflected sensing light and the reference light, and transmits the interference light signal to the data processing assembly through the communication optical cable; the data processing assembly analyzes and processes the interference light signal to obtain multiple physical parameters. Based on this, real-time online monitoring of wideband vibration, stress and strain, and temperature multi-parameters can be realized, which can meet the demand for synchronous monitoring of multiple parameters in complex environments, and the system structure is simple, the equipment cost is low, and it has the value of popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 FIG. 1 is a structural schematic diagram of an optical fiber multi-parameter sensing system in Example 1;

[0043] Figure 2 FIG. 2 is a structural schematic diagram of an optical processing front-end unit in Example 1;

[0044] Figure 3 FIG. 3 is a structural schematic diagram of an optical processing tail-end unit in Example 1;

[0045] Figure 4 FIG. 4 is a schematic diagram of the change of the amplitude of a specific frequency in the spectrum reflecting the temperature change trend with time in Example 2;

[0046] Figure 5 FIG. 5 is a schematic diagram of the change of the amplitude of a specific frequency in the spectrum reflecting the stress and strain change trend with time in Example 2;

[0047] Figure 6 This is a schematic diagram of the change of the phase shift amplitude over time, which reflects the vibration change trend, as illustrated in Example 2. DETAILED DESCRIPTION

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention will be briefly introduced below in conjunction with the drawings and the description of the embodiments or the prior art. Obviously, the following description of the structure of the drawings is only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0049] It should be understood that although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are merely used to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of the exemplary embodiments of the present invention.

[0050] It should be understood that the term "and / or" that may appear in this document is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B may mean: A exists alone, B exists alone, and A and B exist at the same time.

[0051] It will be understood that when an element is referred to herein as being “connected,” “connected,” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present.

[0052] Example 1:

[0053] like Figure 1 As shown, this embodiment provides a fiber optic multi-parameter sensing system, including a light source module, a communication optical cable, a fiber optic interferometer assembly, a sensing optical cable, and a data processing assembly. The output end of the light source module and the input end of the data processing assembly are both connected to the fiber optic interferometer assembly via the communication optical cable. The fiber optic interferometer assembly includes an optical processing front-end unit and an optical processing tail-end unit, which are sequentially connected to the communication optical cable. The optical processing front-end unit is connected to the optical processing tail-end unit via the sensing optical cable.

[0054] The light source module is used to perform phase intra-modulation processing on the laser and transmit the modulated laser carrier to the optical processing front-end unit through the communication optical cable; specifically, in this embodiment, the light source module includes a laser for emitting laser, and an internal modulation component for performing phase intra-modulation processing on the laser; it should be noted that the phase intra-modulation processing function of the light source module can effectively reduce the impact of external environmental changes on the measurement stability of the system.

[0055] The optical processing front-end unit is used to split the laser carrier into sensing light and reference light, and transmit the sensing light to the optical processing tail-end unit through the sensing optical cable; wherein the sensing optical cable is used to perform phase external modulation processing on the optical signal passing therethrough;

[0056] The optical processing tail end unit is used to reflect the sensing light and transmit the reflected sensing light to the optical processing front end unit through the sensing optical cable;

[0057] The optical processing front-end unit is further configured to obtain an interference light signal based on the reflected sensing light and the reference light, and transmit the interference light signal to the data processing component via the communication optical cable;

[0058] The data processing component is used to analyze and process the interference light signal to obtain a variety of physical parameters. Specifically, in this embodiment, the multiple physical parameters include temperature, stress and strain values, and vibration signals.

[0059] This embodiment can achieve synchronous monitoring of multiple physical parameters, while having low cost, low system complexity, and simple deployment and maintenance. Specifically, during the implementation of this embodiment, the light source module performs phase modulation processing on the laser and transmits the modulated laser carrier to the optical processing front-end unit via the communication optical cable; the optical processing front-end unit splits the laser carrier into sensing light and reference light, and transmits the sensing light to the optical processing tail-end unit via the sensing optical cable; the optical processing tail-end unit reflects the sensing light and transmits the reflected sensing light to the optical processing front-end unit via the sensing optical cable; the optical processing front-end unit obtains an interference light signal based on the reflected sensing light and the reference light, and transmits the interference light signal to the data processing component via the communication optical cable; the data processing component analyzes and processes the interference light signal to obtain multiple physical parameters. Based on this, it is possible to simultaneously achieve real-time online monitoring of broadband vibration, stress strain, and temperature parameters, which can meet the needs of synchronous monitoring of multiple parameters in complex environments. At the same time, the system structure is simple, the equipment cost is low, and it has the value of promotion and application.

[0060] like Figure 2As shown, the optical processing front-end unit includes a 2×2 optical coupler and a 3×3 optical coupler, the communication optical cable includes a transmitting optical fiber and two receiving optical fibers, the first input end of the 2×2 optical coupler is connected to the output end of the light source module through the transmitting optical fiber, and is used to receive the laser carrier output by the light source module, the first output end of the 2×2 optical coupler is connected to the sensing optical cable, the second input end and the second output end of the 2×2 optical coupler are respectively connected to any two input ends of the 3×3 optical coupler, and any two output ends of the 3×3 optical coupler are respectively connected to the input end of the data processing component through two receiving optical fibers, and are used to output interference optical signals to the data processing component through the two receiving optical fibers.

[0061] like Figure 3 As shown, the optical processing front-end unit further includes an isolator, and the transmitting optical fiber is connected to the first input end of the 2×2 optical coupler through the isolator.

[0062] In this embodiment, the optical processing tail end unit includes a Faraday rotation mirror, which is connected to the sensing optical cable and is used to receive the sensing light transmitted by the sensing optical cable and perform reflection processing on it.

[0063] In this embodiment, the data processing component includes a first light detector, a second light detector, a data acquisition card, and a signal processing unit. The first light detector and the second light detector constitute a photoelectric conversion unit. The signal processing unit is implemented using a host computer. The first light detector and the second light detector are both connected to the communication optical cable. Specifically, the first light detector and the second light detector are respectively connected to any two output ends of the 3×3 optical coupler through two receiving optical fibers to receive the interference light signal transmitted by the communication optical cable. The first light detector and the second light detector are both connected to the signal acquisition end of the data acquisition card, and the data acquisition card is connected to the signal processing unit.

[0064] The first photodetector and the second photodetector are respectively used to convert the two coherent light signals in the interference light signal into analog electrical signals, retain information of their phase changes over time, and send them to the data acquisition card;

[0065] The data acquisition card is used to convert the two-way analog electrical signals into digital electrical signals and send the two-way digital electrical signals to the signal processing unit;

[0066] The signal processing unit is used to restore the two digital electrical signals into two analog electrical signals, and perform phase demodulation and phase analysis processing based on the two analog electrical signals to obtain multiple physical parameters.

[0067] Specifically, in this embodiment, the first light detector, the second light detector, the data acquisition card and the signal processing unit are all powered by a preset power supply module.

[0068] In addition, the first light detector and the second light detector in this embodiment both use PIN-type photodiodes, which have the characteristics of fast response speed and high linearity, and can efficiently and accurately convert interference light signals into electrical signals; the data acquisition card has a sampling rate of 50kSa / s and supports up to 32 channels of synchronous sampling, which can achieve high-precision and real-time acquisition of multiple signals, ensuring that phase change information is fully retained in complex interference signals; the data acquisition card communicates with the signal processing unit through a USB interface, which simplifies the system access method, improves the stability of data transmission and the convenience of deployment, and is generally beneficial to improving the real-time performance and multi-parameter sensing capabilities of the system.

[0069] Example 2:

[0070] This embodiment discloses a method for operating the optical fiber multi-parameter sensing system as described in Embodiment 1, including:

[0071] The light source module performs phase modulation processing on the laser and transmits the modulated laser carrier to the optical processing front-end unit through the communication optical cable;

[0072] The optical processing front-end unit splits the laser carrier into sensing light and reference light, and transmits the sensing light to the optical processing tail-end unit through the sensing optical cable; wherein the sensing optical cable is used to perform phase external modulation processing on the optical signal passing therethrough;

[0073] The optical processing tail end unit performs reflection processing on the sensing light and transmits the reflected sensing light to the optical processing front end unit through the sensing optical cable;

[0074] The optical processing front-end unit obtains an interference light signal based on the reflected sensing light and the reference light, and transmits the interference light signal to the data processing component through the communication optical cable;

[0075] The data processing component analyzes and processes the interference light signal to obtain a variety of physical parameters.

[0076] In this embodiment, the data processing component includes a first light detector, a second light detector, a data acquisition card, and a signal processing unit. The first light detector and the second light detector are both connected to the communication optical cable to receive the interference light signal transmitted by the communication optical cable. The first light detector and the second light detector are both connected to the signal acquisition terminal of the data acquisition card, and the data acquisition card is connected to the signal processing unit. Correspondingly, the data processing component analyzes and processes the interference light signal to obtain multiple physical parameters, including:

[0077] The first photodetector and the second photodetector respectively convert the two coherent light signals in the interference light signal into analog electrical signals, retain information of their phase changes over time, and send them to the data acquisition card;

[0078] The data acquisition card converts the two analog electrical signals into digital electrical signals, and sends the two digital electrical signals to the signal processing unit;

[0079] The signal processing unit restores the two digital electrical signals into two analog electrical signals, and performs phase demodulation and phase analysis processing according to the two analog electrical signals to obtain a variety of physical parameters.

[0080] Specifically, in this embodiment, the light intensity of the interference light signal received by the first photodetector is for:

[0081] ;

[0082] Where, is the response amplitude of the first photodetector to the interference light signal, that is, the sensitivity of the first photodetector; The interference light signal is t The optical phase time-varying signal at the moment is a time-varying value; is the initial phase difference of the interference light signal sent by the optical processing front-end unit to the first photodetector, the theoretical value of which is a fixed value of 2π / 3;

[0083] The intensity of the interference light signal received by the second photodetector for:

[0084] ;

[0085] Where, is the amplitude of the interference light signal received by the second photodetector; is the initial phase difference of the interference light signal sent by the optical processing front-end unit to the second photodetector, and the theoretical value of this value is a fixed value of -2π / 3.

[0086] It should be noted that the intensity variation value of the interference light signal is generated due to phase variation. In this embodiment, the corresponding interference light intensity time-varying signal is obtained through the first photodetector and the second photodetector.

[0087] In this embodiment, the multiple physical parameters include temperature and stress and strain values; correspondingly, the signal processing unit performs phase demodulation and phase analysis processing on the two analog electrical signals to obtain multiple physical parameters, including:

[0088] The signal processing unit performs phase demodulation processing on the two analog electrical signals to obtain an optical phase time-varying signal. In this embodiment, the optical phase time-varying signal can be expressed as:

[0089] ;

[0090] Where, , ;in,

[0091] ;

[0092] ;

[0093] in, The interference light signal t The optical phase time-varying signal at the moment, The interference light signal received by the first photodetector is t Normalized signal at time; The interference light signal received by the second photodetector is t Normalized signal at time; is the normalized signal With the normalized signal The difference between is the normalized signal With the normalized signal The sum between.

[0094] It should be noted that the phase information of the interfering optical signal is the sum of the phase changes of the two coherent optical signals. Therefore, it has better sensitivity to low-frequency phase disturbance signals. As time changes, the maximum and minimum values ​​closest to the interference at the current moment can be easily obtained. Using the above method, the time-varying optical phase signal can be obtained very accurately.

[0095] The signal processing unit performs Fourier transform processing on the optical phase time-varying signal to obtain a frequency spectrum and a phase spectrum, and extracts a spectral component in the frequency spectrum that is consistent with the internal modulation frequency of the light source module, the amplitude of which is proportional to the change in optical fiber length;

[0096] Specifically, the spectral components are:

[0097] ;

[0098] Among them, Δ φ ( t )for t The optical phase time-varying signal at time , FFT( ) represents the Fourier transform function, and max( ) represents the maximum value function.

[0099] The signal processing unit obtains the optical path difference of the interference light signal based on the spectral components, and then obtains the temperature and stress-strain values ​​of the sensor optical cable based on the optical path difference. It should be noted that the spectral components and the optical path difference of the interference light signal are in direct proportion, and the proportional coefficient is related to the amplitude of the internal modulation signal of the light source module; the relationship between the optical path difference and the temperature and stress-strain value parameters of the sensor optical cable is related to the packaging process and layout method of the sensor optical cable used. As an example, Figure 4 A schematic diagram of the change in the amplitude of a specific frequency (abbreviated as "amplitude 1") in the spectrum reflecting the temperature change trend over time is given, reflecting the trend of gradual increase and then gradual decrease in temperature; Figure 5 A schematic diagram of the change of the amplitude of a specific frequency (abbreviated as "amplitude 2") in the spectrum reflecting the trend of stress and strain changes over time is given, reflecting the changing trend of the stress and strain values.

[0100] In this embodiment, the multiple physical parameters further include a vibration signal; correspondingly, after the signal processing unit extracts the spectrum component consistent with the internal modulation frequency of the light source module from the spectrum, the method further includes:

[0101] The signal processing unit modifies the spectral components to obtain modified spectral components, and performs inverse Fourier transform on the modified spectral components and the phase spectrum to obtain a vibration phase time-varying signal reflecting the external vibration characteristics; as an example, Figure 6 A schematic diagram of the time-varying phase shift amplitude (abbreviated as "amplitude 3"), which reflects the vibration change trend, is given. This is also a schematic diagram of the time-varying vibration phase signal.

[0102] The signal processing unit demodulates the vibration phase time-varying signal to obtain a vibration signal.

[0103] It should be noted that in this embodiment, the optical time-varying phase signal contains two types of modulation components: an internal laser modulation signal with a fixed frequency and amplitude that varies with the optical path (fiber length), corresponding to temperature and stress-strain variations; and an external disturbance signal with a variable frequency and rapid temporal variations, corresponding to dynamic disturbances such as vibration. Based on this, the phase information can be used to analyze the various physical parameter data hidden within.

[0104] It should be understood that the original optical phase time-varying signal is a mixed signal containing internal modulation and external disturbance information; while the vibration phase time-varying signal is a signal that is reconstructed by removing the internal modulation component and represents the time domain phase change of the external vibration behavior alone, which is used to identify dynamic disturbance characteristics such as mechanical vibration or sound waves.

[0105] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A method for operating a fiber optic multi-parameter sensing system, characterized in that: The optical fiber multi-parameter sensing system includes a light source module, a communication optical cable, an optical fiber interference component, a sensing optical cable and a data processing component. The output end of the light source module and the input end of the data processing component are both connected to the optical fiber interference component via the communication optical cable. The optical fiber interference component includes an optical processing front-end unit and an optical processing tail-end unit connected to the communication optical cable in sequence. The optical processing front-end unit is connected to the optical processing tail-end unit via the sensing optical cable. The method includes: The light source module performs phase modulation processing on the laser and transmits the modulated laser carrier to the optical processing front-end unit through the communication optical cable; The optical processing front-end unit splits the laser carrier into sensing light and reference light, and transmits the sensing light to the optical processing tail-end unit through the sensing optical cable; wherein the sensing optical cable is used to perform phase external modulation processing on the optical signal passing therethrough; The optical processing tail end unit performs reflection processing on the sensing light and transmits the reflected sensing light to the optical processing front end unit through the sensing optical cable; The optical processing front-end unit obtains an interference light signal based on the reflected sensing light and the reference light, and transmits the interference light signal to the data processing component through the communication optical cable; The data processing component analyzes and processes the interference light signal to obtain a variety of physical parameters; The data processing component includes a first light detector, a second light detector, a data acquisition card, and a signal processing unit. The first light detector and the second light detector are both connected to the communication optical cable to receive the interference light signal transmitted by the communication optical cable. The first light detector and the second light detector are both connected to the signal acquisition terminal of the data acquisition card, and the data acquisition card is connected to the signal processing unit. Correspondingly, the data processing component analyzes and processes the interference light signal to obtain multiple physical parameters, including: The first photodetector and the second photodetector respectively convert the two coherent light signals in the interference light signal into analog electrical signals and send them to the data acquisition card; The data acquisition card converts the two analog electrical signals into digital electrical signals, and sends the two digital electrical signals to the signal processing unit; The signal processing unit converts the two digital electrical signals into two analog electrical signals, and performs phase demodulation and phase analysis on the two analog electrical signals to obtain a variety of physical parameters; The various physical parameters include temperature and stress and strain values. Correspondingly, the signal processing unit performs phase demodulation and phase analysis processing on the two analog electrical signals to obtain various physical parameters, including: The signal processing unit performs phase demodulation processing on the two analog electrical signals to obtain an optical phase time-varying signal; The signal processing unit performs Fourier transform processing on the optical phase time-varying signal to obtain a frequency spectrum and a phase spectrum, and extracts a frequency spectrum component consistent with the internal modulation frequency of the light source module from the frequency spectrum; The signal processing unit obtains the optical path difference of the interference light signal according to the spectral components, and then obtains the temperature and stress-strain values ​​of the sensing optical cable according to the optical path difference.

2. The method of claim 1, wherein: The spectral components are: ； Among them, Δ φ ( t )for t The optical phase time-varying signal at time , FFT( ) represents the Fourier transform function, and max( ) represents the maximum value function.

3. The method of claim 1, wherein: The multiple physical parameters also include a vibration signal; correspondingly, after the signal processing unit extracts the spectrum component consistent with the internal modulation frequency of the light source module from the spectrum, the method further includes: The signal processing unit modifies the spectral components to obtain modified spectral components, and performs inverse Fourier transform on the modified spectral components and the phase spectrum to obtain a vibration phase time-varying signal reflecting the external vibration characteristics; The signal processing unit demodulates the vibration phase time-varying signal to obtain a vibration signal.

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