A fiber grating distributed measurement device and method based on microwave domain and light domain demodulation

Abstract

The application discloses a kind of based on microwave field and light field demodulation's fiber grating distributed measurement device and method, measurement device includes broadband light source, polarizer, polarization controller, electro-optic modulator, vector network analyzer, first radio frequency amplifier, 1:99 beam splitter, bias control board, first erbium-doped fiber amplifier, optical circulator, 1x2 optical fiber coupler, transmission optical fiber, FBG array sensing optical fiber, photodetector, second radio frequency amplifier, computer, second erbium-doped fiber amplifier, fiber grating demodulator.The application can realize the spatial continuous distributed measurement of temperature / strain / pressure and the like parameters of fiber along line and high spatial resolution point distribution measurement.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of photoelectric testing, and particularly relates to a fiber grating distributed measurement device and method based on microwave domain and light domain demodulation. BACKGROUND

[0002] The distributed fiber sensing technology has been widely concerned by researchers at home and abroad due to its advantages of electrical insulation, corrosion resistance, anti-electromagnetic interference, small size and distribution, and has been widely applied to safety monitoring and fault diagnosis in many fields such as petrochemical industry, dam and bridge, aerospace, power transmission, optical fiber communication and the like.

[0003] At present, the most commonly used distributed fiber sensing technology is the distributed fiber sensing technology based on Raman scattering, Rayleigh scattering and Brillouin scattering and the quasi-distributed fiber sensing technology based on Fiber Bragg Grating (FBG). The former distributed fiber sensing technology is mainly based on the change of the inherent backscattering signal in the optical fiber caused by the influence of external factors for sensing, which has the advantages of long sensing distance, no measurement blind area and the like; but often due to the low scattering coefficient and system signal-to-noise ratio in the optical fiber, and the inherent defects of the technology itself, the spatial resolution, measurement sensitivity and measurement accuracy of the distributed sensing system are affected, and there is often a contradiction between the spatial resolution and the sensing distance; in order to solve such problems, many times of averaging algorithm or method of improving the scattering coefficient is usually used, but this will also cause the system response time and cost to increase greatly. Compared with the distributed fiber sensing technology based on backscattering, the quasi-distributed fiber sensing technology based on FBG can realize distributed measurement with higher spatial resolution, measurement accuracy and sensitivity due to its characteristics of higher signal-to-noise ratio and physical positioning, and with the development of multiplexing technologies such as time division multiplexing, wavelength division multiplexing and space division multiplexing, a large-scale sensing network can be constructed based on the quasi-distributed FBG array; but due to the measurement mechanism and technical limitations of itself, it is difficult to realize spatial continuous distributed measurement; and due to the limitation of demodulation technology and FBG processing technology, the multiplexing capacity of the system is limited, which further affects the sensing distance. In many cases, point measurement with high spatial resolution at multiple spatial points and spatial continuous distributed measurement in the whole space need to be considered at the same time to obtain monitoring data of important nodes and distributed average monitoring data based on the system spatial resolution, and the existing fiber sensing technology is difficult to consider both. SUMMARY

[0004] The application aims at overcoming the defects in the prior art, solving the problem that the existing optical fiber sensing technology is difficult to simultaneously realize spatial continuous distributed measurement and high spatial resolution point distributed measurement, and providing an optical fiber grating distributed measurement device and method based on microwave domain and optical domain demodulation.

[0005] The application is realized by the following technical scheme.

[0006] The application discloses an optical fiber grating distributed measurement device based on microwave domain and optical domain demodulation.

[0007] The broadband light source, the polarizer, the polarization controller and the electro-optical modulator are sequentially connected; the signal output end of the vector network analyzer is connected with the signal input end of the first radio frequency amplifier through a high-frequency cable; the signal output end of the first radio frequency amplifier is connected with the modulation signal input end of the electro-optical modulator through a high-frequency cable; the output end of the electro-optical modulator is connected with the input end of the 1:99 beam splitter; the 1% signal output end of the 1:99 beam splitter is connected with the optical signal input end of the bias control board; the bias control board is connected with the bias interface of the electro-optical modulator; the 99% signal output end of the 1:99 beam splitter is connected with the input end of the first erbium-doped fiber amplifier; the output end of the first erbium-doped fiber amplifier is connected with the incident end of the optical circulator; the reflection end of the optical circulator is connected with the a port of the 1x2 optical fiber coupler; the c port of the 1x2 optical fiber coupler is connected with the transmission optical fiber; the transmission optical fiber is connected with the FBG array sensing optical fiber; the output end of the optical circulator is connected with the incident end of the photoelectric detector; the emission end of the photoelectric detector is connected with the signal input end of the second radio frequency amplifier through a high-frequency cable; the signal output end of the second radio frequency amplifier is connected with the signal input end of the vector network analyzer through a high-frequency cable; the vector network analyzer is connected with the computer; the b port of the 1x2 optical fiber coupler is connected with the input end of the second erbium-doped fiber amplifier; the output end of the second erbium-doped fiber amplifier is connected with the input end of the optical fiber grating demodulator; and the optical fiber grating demodulator is connected with the computer.

[0008] Further, the FBG array sensing optical fiber is processed with FBG arrays with different center wavelengths in the fiber core, the interval of adjacent FBGs is greater than the coherence length of the broadband light source and less than the coherence length of the microwave sweep signal generated by the vector network analyzer.

[0009] Further, the bias control board is an automatic bias point controller, which can modulate the bias point of the electro-optical modulator through real-time feedback to ensure stable operation of the electro-optical modulator in various operating environments.

[0010] The application also provides a fiber grating distributed measurement method based on the above measurement device, including the following steps:

[0011] The light signal output by the broadband light source is polarized and modulated by the polarizer and the polarization controller, and then enters the electro-optical modulator; the microwave signal output by the vector network analyzer is amplified by the first radio frequency amplifier, and then enters the electro-optical modulator; the light signal modulated by the microwave signal is output from the electro-optical modulator, and then enters the 1:99 beam splitter; the light signal output from the 1% output end of the 1:99 beam splitter enters the bias control board; the bias control signal generated by the bias control board is transmitted to the electro-optical modulator; the light signal output from the 99% output end of the 1:99 beam splitter enters the first erbium-doped fiber amplifier, and is amplified by the first erbium-doped fiber amplifier, and then input to the optical circulator; the light signal output from the reflection end of the optical circulator is then input to the a port of the 1x2 optical fiber coupler, and then output from the c port of the 1x2 optical fiber coupler and enters the transmission optical fiber; finally, the light signal is reflected at the fiber Bragg grating FBG of the FBG array sensing optical fiber after being transmitted through the transmission optical fiber, the microwave signal modulated on the light signal meets at the meeting point in the FBG array sensing optical fiber to form a microwave interference signal; the microwave interference signal is output from the a port of the 1x2 optical fiber coupler and enters the reflection end of the optical circulator, and then output from the exit end of the optical circulator and enters the photodetector; the microwave interference signal is converted into an electrical signal by the photodetector, and then enters the second radio frequency amplifier for amplification; the amplified electrical signal is collected by the vector network analyzer; the light signal reflected by the FBG array sensing optical fiber is output from the b port of the 1x2 optical fiber coupler and enters the second erbium-doped fiber amplifier, and is amplified by the second erbium-doped fiber amplifier, and then enters the fiber grating demodulator; the computer is used for controlling the vector network analyzer and the fiber grating demodulator and processing and analyzing the received data.

[0012] Further, the vector network analyzer is swept to obtain the microwave signal interference spectrum reflected by the FBG array sensing fiber; the spatial distribution information corresponding to the FBG array sensing fiber reflected signal is obtained by performing inverse Fourier transform on the collected microwave signal interference spectrum; the optical path of the FBG array sensing fiber reflected signal changes due to the influence of external pressure, strain and temperature factors, and the optical path change amount of the FBG array sensing fiber reflected signal has a corresponding relationship with the frequency shift amount of the microwave signal interference spectrum, and the to-be-measured parameter is obtained by inversion through the frequency shift amount of the microwave signal interference spectrum; finally, the spatial continuous distributed measurement of the pressure, strain and temperature parameters is realized based on the FBG array sensing fiber through the microwave domain demodulation.

[0013] Further, the FBG array sensing fiber reflected spectrum of the fiber Bragg grating FBG with different center wavelengths is obtained by the fiber grating demodulator; the center wavelength of the fiber Bragg grating FBG reflected spectrum is offset due to the influence of external pressure, strain and temperature factors on the FBG array sensing fiber; the to-be-measured parameter is obtained through the offset amount of the center wavelength of the fiber Bragg grating FBG reflected spectrum, and the micron-level high spatial resolution point distribution measurement of the pressure, strain and temperature parameters is realized through the light domain demodulation.

[0014] Compared with the prior art, the technical scheme of the present application has the following advantages:

[0015] 1. The measurement device and method can realize spatial continuous distributed measurement of pressure, strain, temperature and other parameters without blind area, solve the blind area problem existing in the spatial distribution measurement of the existing fiber grating sensing technology, and greatly improve the comprehensiveness and reliability of the measurement.

[0016] 2. The device and method have the advantages of microwave, fiber grating and fiber sensing technology. On the one hand, the light signal can be used as the carrier of the microwave signal, and the spatial continuous distributed measurement can be realized by interference demodulation in the microwave domain based on microwave interference, which has the advantage of not being affected by the type of optical fiber, optical transmission mode and optical polarization state change; on the other hand, the spectrum of the light signal reflected by the fiber grating is demodulated in the light domain, and high spatial resolution point distribution measurement is realized, so that the measurement system has high precision and high sensitivity.

[0017] 3. The measurement device and method have high flexibility and strong adaptability. According to actual needs, different types of waveguides can be selected to meet different sensitivity requirements, thereby effectively controlling the cost. At the same time, by flexibly setting the grating spacing, the demand for different sensing spatial resolution can be met, so that the system has strong adaptability and wide application prospect.

[0018] 4. By fusing the demodulation techniques of microwave domain and optical domain, the present application effectively solves the deficiencies of the prior art in improving system response time and reducing cost. High-performance distributed measurement can be achieved without a large number of averaging algorithms or improving the scattering coefficient, providing an efficient and economical solution.

[0019] 5. By using the physical positioning characteristics of FBG, the present application can accurately identify the position of the measurement point, thereby effectively balancing between point measurement with high spatial resolution and distributed measurement with overall spatial resolution, obtaining accurate monitoring data of important nodes and average monitoring data of the overall space. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structural schematic diagram of the optical fiber grating distributed measurement device of the present application.

[0021] Figure 2 is an example diagram of the FBG array sensing optical fiber in the optical fiber grating distributed measurement device of the present application.

[0022] Figure 3 is an example diagram of the multi-channel FBG array sensing optical fiber provided in Embodiment 2 of the present application.

[0023] Reference signs: 1 - broadband light source, 2 - polarizer, 3 - polarization controller, 4 - electro-optical modulator, 5 - vector network analyzer, 6 - first radio frequency amplifier, 7 - 1:99 beam splitter, 8 - bias control board, 9 - first erbium-doped fiber amplifier, 10 - optical circulator, 11 - 1x2 fiber coupler, 12 - transmission optical fiber, 13 - FBG array sensing optical fiber, 14 - photodetector, 15 - second radio frequency amplifier, 16 - computer, 17 - second erbium-doped fiber amplifier, 18 - fiber grating demodulator, 19 - 2xN fiber coupler, 20 - N transmission optical fibers, 21 - N FBG array sensing optical fibers. DETAILED DESCRIPTION

[0024] The present application will be further described in detail below in conjunction with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0025] Embodiment 1:

[0026] As Figure 1As shown: the fiber grating distributed measurement device based on microwave domain and light domain demodulation, including broadband light source 1, polarizer 2, polarization controller 3, electro-optic modulator 4, vector network analyzer 5, first radio frequency amplifier 6, 1:99 beam splitter 7, bias control board 8, first erbium-doped fiber amplifier 9, optical circulator 10, 1x2 fiber coupler 11, transmission fiber 12, FBG array sensing fiber 13, photodetector 14, second radio frequency amplifier 15, computer 16, second erbium-doped fiber amplifier 17, fiber grating demodulator 18.

[0027] The output end of broadband light source 1 is connected with the input end of polarizer 2, the output end of polarizer 2 is connected with the input end of polarization controller 3, the output end of polarization controller 3 is connected with the input end of electro-optic modulator 4; the signal output end of vector network analyzer 5 is connected with the signal input end of first radio frequency amplifier 6 through high-frequency cable; the signal output end of first radio frequency amplifier 6 is connected with the modulation signal input end of electro-optic modulator 4 through high-frequency cable; the output end of electro-optic modulator 4 is connected with the input end of 1:99 beam splitter 7; the 1% signal output end of 1:99 beam splitter 7 is connected with the optical signal input end of bias control board 8; bias control board 8 is connected with the bias interface of electro-optic modulator 4; the 99% signal output end of 1:99 beam splitter 7 is connected with the input end of first erbium-doped fiber amplifier 9; the output end of first erbium-doped fiber amplifier 9 is connected with the incident end of optical circulator 10; the reflection end of optical circulator 10 is connected with the a port of 1x2 fiber coupler 11; the c port of 1x2 fiber coupler 11 is connected with transmission fiber 12; transmission fiber 12 is connected with FBG array sensing fiber 13; the output end of optical circulator 10 is connected with the incident end of photodetector 14; the emission end of photodetector 14 is connected with the signal input end of second radio frequency amplifier 15 through high-frequency cable; the signal output end of second radio frequency amplifier 15 is connected with the signal input end of vector network analyzer 5 through high-frequency cable, vector network analyzer 5 is connected with computer 16. The b port of 1x2 fiber coupler 11 is connected with the input end of second erbium-doped fiber amplifier 17; the output end of second erbium-doped fiber amplifier 17 is connected with the input end of fiber grating demodulator 18; fiber grating demodulator 18 is connected with computer 16.

[0028] In specific implementation, the fiber core of FBG array sensing fiber 13 is processed with micro-reflection fiber Bragg grating FBG array with different center wavelengths, the interval of adjacent fiber Bragg grating FBG corresponds to optical path difference greater than the coherence length of broadband light source and less than the coherence length of microwave sweep signal generated by vector network analyzer. The schematic diagram of FBG array sensing fiber is shown in Figure 2 .

[0029] In the embodiment, the bias control board 8 is an automatic bias point controller, which can modulate the bias point of the electro-optical modulator 4 through real-time feedback to ensure stable operation of the electro-optical modulator 4 in various operating environments.

[0030] Preferably, the embodiment also provides a fiber grating distributed measurement method based on microwave domain and optical domain demodulation, which is implemented in the fiber grating distributed measurement device based on microwave domain and optical domain demodulation described above, and is implemented by the following steps:

[0031] The light signal output by the broadband light source 1 is polarized and modulated by the polarizer 2 and the polarization controller 3, and then enters the electro-optical modulator 4; the microwave signal output by the vector network analyzer 5 is amplified by the first radio frequency amplifier 6, and then enters the electro-optical modulator 4; the light signal modulated by the microwave signal is output from the electro-optical modulator 4, and then enters the 1:99 optical splitter 7; the light signal output from the 1% output end of the 1:99 optical splitter 7 enters the bias control board 8; the bias control signal generated by the bias control board 8 is transmitted to the electro-optical modulator 4; the light signal output from the 99% output end of the 1:99 optical splitter 7 enters the first erbium-doped fiber amplifier 9, is amplified by the first erbium-doped fiber amplifier 9, and then enters the optical circulator 10; the light signal is output from the reflection end of the optical circulator 10, and then enters the a port of the 1×2 optical fiber coupler 11, is output from the c port of the 1×2 optical fiber coupler 11, and then enters the transmission optical fiber 12; the light signal is reflected at the fiber Bragg grating FBG of the FBG array sensing optical fiber 13 after passing through the transmission optical fiber 12, the microwave signal modulated on the light signal interferes to form a microwave interference signal at the meeting place; the microwave interference signal is output from the a port of the 1×2 optical fiber coupler 11, enters the reflection end of the optical circulator 10, is output from the exit end of the optical circulator 10, and then enters the photodetector 14; the microwave interference signal is converted into an electrical signal by the photodetector 14, and then enters the second radio frequency amplifier 15 for amplification; the amplified electrical signal is collected by the vector network analyzer 5; the light signal reflected by the FBG array sensing optical fiber 13 is output from the b port of the 1×2 optical fiber coupler 11, enters the second erbium-doped fiber amplifier 17, is amplified by the second erbium-doped fiber amplifier 17, and then enters the fiber grating demodulator 18; the computer 16 is used for controlling the vector network analyzer 5 and the fiber grating demodulator 18, and processing and analyzing the received data.

[0032] The microwave signal interference spectrum reflected by the FBG array sensing optical fiber 13 can be obtained by sweeping the vector network analyzer 5. The spatial distribution information corresponding to the FBG reflection signal is obtained by performing inverse Fourier transform on the collected microwave signal interference spectrum; the window function is used to select two adjacent FBG reflection signals, and the interference spectrum of the selected two FBG reflection signals is reconstructed by Fourier transform; the FBG array sensing optical fiber 13 is affected by external pressure, strain, temperature and other factors, and the length and refractive index of the optical fiber at the corresponding position will change, thereby causing the optical path of the FBG reflection signal to change, and further causing the frequency shift of the microwave signal interference spectrum. There is a corresponding relationship between the pressure, strain, temperature and the optical path change amount, and there is a corresponding relationship between the optical path change amount of the FBG reflection signal and the frequency shift amount of the microwave signal interference spectrum, and the to-be-measured parameters can be inversely obtained through the frequency shift amount of the microwave signal interference spectrum. Thus, by demodulating in the microwave domain, the spatially continuous distributed measurement of the pressure, strain, temperature and other parameters is realized based on the FBG array sensing optical fiber 13.

[0033] The reflection spectrum of the fiber Bragg grating FBG with different center wavelengths in the FBG array sensing optical fiber 13 is obtained by the fiber grating demodulator 18. The FBG array sensing optical fiber 13 is affected by external pressure, strain, temperature and other factors, causing the grating pitch and effective refractive index of the fiber Bragg grating FBG to change, and further causing the center wavelength of the fiber Bragg grating FBG reflection spectrum to shift. There is a corresponding relationship between the pressure, strain, temperature and the shift amount of the center wavelength of the fiber Bragg grating FBG reflection spectrum, and the to-be-measured parameters can be obtained through the shift amount of the center wavelength of the fiber Bragg grating FBG reflection spectrum, thereby demodulating in the optical domain, and simultaneously realizing the high spatial resolution point distribution measurement of the pressure, strain, temperature and other parameters.

[0034] Embodiment 2:

[0035] The difference between this embodiment and embodiment 1 is that N FBG array sensing optical fibers are arranged in this embodiment to form a multi-channel FBG array sensing optical fiber array, and the N FBG array sensing optical fibers are connected with the 2xN fiber coupler 19 through the N transmission optical fibers 20, as shown in Figure 3 Based on wavelength division multiplexing and space division multiplexing, multi-channel distributed measurement of multiple parameters and high spatial resolution point distribution measurement are realized.

[0036] Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The technical features not described in the present application can be realized by or using the prior art, which will not be described here; the above embodiments and drawings are only used to illustrate the technical solutions of the present application and are not a limitation on the present application. The present application is described in detail with reference to the preferred embodiments, and those skilled in the art should understand that the changes, modifications, additions or substitutions made by those skilled in the art within the essential scope of the present application do not deviate from the purpose of the present application, and should also belong to the protection scope of the claims of the present application.

[0037] The present application is not limited to the above-described embodiments. The above description of specific embodiments is intended to describe and illustrate the technical solutions of the present application, and the specific embodiments described above are only illustrative and not limiting. Without departing from the purpose of the present application and the scope protected by the claims, those skilled in the art can make many forms of specific changes under the inspiration of the present application, which are all within the protection scope of the present application.

Claims

1. A fiber grating distributed measurement device based on microwave domain and light domain demodulation, characterized in that, The wideband light source (1), the polarizer (2), the polarization controller (3), the electro-optical modulator (4) are sequentially connected; the signal output end of the vector network analyzer (5) is connected with the signal input end of the first radio frequency amplifier (6) through high-frequency cable in sequence; the signal output end of the first radio frequency amplifier (6) is connected with the modulation signal input end of the electro-optical modulator (4) through high-frequency cable; the output end of the electro-optical modulator (4) is connected with the input end of the 1:99 optical splitter (7); the 1% signal output end of the 1:99 optical splitter (7) is connected with the optical signal input end of the bias control board (8); the bias control board (8) is connected with the bias interface of the electro-optical modulator (4); the 99% signal output end of the 1:99 optical splitter (7) is connected with the input end of the first erbium-doped fiber amplifier (9); the output end of the first erbium-doped fiber amplifier (9) is connected with the incident end of the optical circulator (10); the reflection end of the optical circulator (10) is connected with the a port of the 1×2 fiber coupler (11); the c port of the 1×2 fiber coupler (11) is connected with the transmission fiber (12); the transmission fiber (12) is connected with the FBG array sensing fiber (13); the output end of the optical circulator (10) is connected with the incident end of the photodetector (14); the emission end of the photodetector (14) is connected with the signal input end of the second radio frequency amplifier (15) through high-frequency cable; the signal output end of the second radio frequency amplifier (15) is connected with the signal input end of the vector network analyzer (5) through high-frequency cable, and the vector network analyzer (5) is connected with the computer (16); the b port of the 1×2 fiber coupler (11) is connected with the input end of the second erbium-doped fiber amplifier (17); the output end of the second erbium-doped fiber amplifier (17) is connected with the input end of the fiber grating demodulator (18); the fiber grating demodulator (18) is connected with the computer (16), and the fiber core of the FBG array sensing fiber (13) is processed with fiber Bragg grating FBG array with different center wavelengths. The distance between adjacent fiber Bragg gratings FBG corresponding to the optical path difference is greater than the coherence length of the wideband light source (1) and less than the coherence length of the microwave sweep signal generated by the vector network analyzer (5). 2.The fiber grating distributed measurement device based on microwave domain and optical domain demodulation according to claim 1, wherein, The bias control board (8) is an automatic bias point controller, which can feedback and adjust the bias point of the electro-optical modulator (4) in real time to ensure that the electro-optical modulator (4) works stably in various operating environments. 3.The fiber grating distributed measurement device based on microwave domain and optical domain demodulation according to claim 1, wherein, The method comprises the following steps:

4. A fiber grating distributed measurement method based on the fiber grating distributed measurement device according to any one of claims 1-3, characterized in that, ​ The light signal output by the broadband light source (1) is modulated by a polarizer (2) and a polarization controller (3), and then enters an electro-optical modulator (4); the microwave signal output by the vector network analyzer (5) is amplified by a first radio frequency amplifier (6) and then enters the electro-optical modulator (4); the light signal modulated by the microwave signal is output from the electro-optical modulator (4) and then enters a 1:99 beam splitter (7); the light signal output from the 1% output end of the 1:99 beam splitter (7) enters a bias control board (8); the bias control signal generated by the bias control board (8) is transmitted to the electro-optical modulator (4); the light signal output from the 99% output end of the 1:99 beam splitter (7) enters a first erbium-doped fiber amplifier (9), is amplified by the first erbium-doped fiber amplifier (9), and then enters an optical circulator (10); the light signal output from the reflection end of the optical circulator (10) enters the a port of a 1x2 optical fiber coupler (11), is output from the c port of the 1x2 optical fiber coupler (11), and then enters a transmission optical fiber (12); finally, the light signal is reflected at the fiber Bragg grating (FBG) of the FBG array sensing optical fiber (13) after being transmitted through the transmission optical fiber (12); the microwave signal modulated on the light signal meets at the interference point in the FBG array sensing optical fiber (13) and forms a microwave interference signal; the microwave interference signal is output from the a port of the 1x2 optical fiber coupler (11), enters the reflection end of the optical circulator (10), is output from the exit end of the optical circulator (10), and then enters a photodetector (14); the microwave interference signal is converted into an electrical signal by the photodetector (14), enters a second radio frequency amplifier (15), and is amplified; the amplified electrical signal is collected by the vector network analyzer (5); the light signal reflected by the FBG array sensing optical fiber (13) is output from the b port of the 1x2 optical fiber coupler (11), enters a second erbium-doped fiber amplifier (17), is amplified by the second erbium-doped fiber amplifier (17), and then enters an optical fiber grating demodulator (18); a computer (16) is used for controlling the vector network analyzer (5) and the optical fiber grating demodulator (18) and processing and analyzing the received data.

5. The fiber grating distributed measurement method according to claim 4, wherein, By sweeping the vector network analyzer (5), the microwave signal interference spectrum reflected by the FBG array sensing optical fiber (13) is obtained; the spatial distribution information corresponding to the FBG array sensing optical fiber (13) reflected signal is obtained by performing inverse Fourier transform on the collected microwave signal interference spectrum; the optical path of the FBG reflected signal changes due to the influence of external pressure, strain, and temperature factors on the FBG array sensing optical fiber (13), and the optical path change amount of the FBG reflected signal has a corresponding relationship with the frequency shift amount of the microwave signal interference spectrum; the to-be-measured parameter is obtained by inversely calculating the frequency shift amount of the microwave signal interference spectrum; finally, the spatial continuous distributed measurement of the pressure, strain, and temperature parameters is realized based on the FBG array sensing optical fiber (13) by demodulating in the microwave domain.

6. The fiber grating distributed measurement method according to claim 4, wherein, The reflection spectrum of the fiber Bragg grating FBG with different center wavelengths in the FBG array sensing optical fiber (13) is obtained by a fiber grating demodulator (18); the FBG array sensing optical fiber (13) is affected by external pressure, strain and temperature factors, so that the center wavelength of the reflection spectrum of the fiber Bragg grating FBG is offset; The to-be-measured parameters are obtained through the offset amount of the center wavelength of the reflection spectrum of the fiber Bragg grating FBG, and the point distribution measurement of the micron-level high spatial resolution of the pressure, strain and temperature parameters is realized through optical domain demodulation.

Images