Optical frequency domain reflection strain sensing method based on phase demodulation and cross-correlation combination

Abstract

The invention discloses an optical frequency domain reflection strain sensing method based on the combination of phase demodulation and cross-correlation, and the method comprises the steps: collecting backward Rayleigh scattering signals before and after the strain of a to-be-measured optical fiber, and extracting the phase information of a reference signal and a measurement signal through Fourier transform; a cross-correlation algorithm is combined to match a reference signal and a measurement signal at the same position of the optical fiber, and a dislocation phenomenon on a distance domain is corrected; calculating the relative phase of the matched reference signal and measurement signal at the same position, and performing phase unwrapping; distinguishing a fiber grating area and a non-grating area, and performing continuous correction on phase data by adopting a linear regression fitting algorithm so as to eliminate jump errors; on the basis of the differential relative phase, a window where the sudden change position is located is determined according to the window width obtained in the cross-correlation algorithm, segmented assignment is conducted on the strain of the window, and finally complete strain field distribution data are output. According to the method, the stability, the anti-interference capability and the measurement reliability of the phase demodulation method are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of distributed optical fiber sensing, and in particular relates to an optical frequency domain reflection strain sensing method based on the combination of phase demodulation and cross-correlation. Background Art

[0002] Distributed fiber optic sensing technology uses optical fibers as sensing units and transmission elements to achieve continuous measurement of environmental parameters distributed along the optical fiber. It has become an important technical means in research fields such as transportation, submarine cable monitoring, power communications, aerospace, oil and gas exploration, national defense and military industry, and pipeline transportation.

[0003] Among various distributed fiber optic sensing technologies, the optical frequency domain reflectometry technology based on backward Rayleigh scattering has a relatively simple sensing system structure and is easier to detect optical signals. It has high spatial resolution, measurement accuracy, and real-time sensing in short-distance measurements. Therefore, it is widely used in high-precision testing scenarios such as precision equipment testing, component testing, material and assembly testing, etc.

[0004] In existing OFDR (Optical Frequency Domain Reflectometry) technology, factors such as weak Rayleigh scattering signal intensity and nonlinear tuning of the light source restrict the improvement of its spatial resolution, sensing accuracy and other performance. OFDR based on phase demodulation has the potential to achieve theoretical spatial resolution, but it is highly dependent on the accuracy of phase information. Interference such as random optical noise and environmental vibration is the main factor inhibiting this performance, which may lead to phase jumps or demodulation errors.

[0005] Existing OFDR distributed fiber strain sensing research also includes: large strain step-by-step demodulation method, based on the cross-correlation analysis of the dynamic reference Rayleigh scattering spectrum and the measured Rayleigh scattering spectrum to determine the spectral offset, which is then converted into strain; multi-frequency detection and nearest neighbor analysis based on phase demodulation can eliminate the interference of fading noise and obtain the phase signal.

[0006] However, OFDR systems using different methods differ in their sensing principles. How to ensure the stability of the strain measurement system while maintaining high spatial resolution is a difficult problem that urgently needs to be solved in this technical field. Summary of the Invention

[0007] The problem to be solved by the present invention is to provide an optical frequency domain reflection strain sensing method based on phase demodulation and cross-correlation, which is used to solve the problems of insufficient spatial resolution of existing strain demodulation technology and the influence of optical noise on phase demodulation, and improve the stability of the strain measurement system.

[0008] The present invention adopts the following technical solution: an optical frequency domain reflection strain sensing method based on phase demodulation and cross-correlation, comprising the following steps:

[0009] Step 1: Use the OFDR sensing system to collect two sets of Rayleigh backscattering signals before and after the optical fiber is strained, one set is the reference signal and the other set is the measurement signal;

[0010] Step 2: Perform Fourier transform on the two sets of collected backscattered Rayleigh signals and extract phase information to obtain the reference signal phase φ r ={φ r (x1),φ r (x2),...,φ r (x i )} and the measured signal phase φ s ={φ s (x1),φ s (x2),...,φ s (x i )}, where x i is the position of the i-th sampling point; perform a modulo operation on the phase information after Fourier transformation to obtain a spectrum signal-distance map;

[0011] Step 3: Using a cross-correlation algorithm, by comparing the matching degree of different signal segments near the same position in the spectrum signal-distance diagram, the best match between the reference signal and the measurement signal at the same position on the optical fiber is achieved. This corrects the misalignment phenomenon in the optical fiber distance domain and calculates the strain along the entire optical fiber.

[0012] Step 4: Subtract the phases of the matched reference signal and the measured signal at the same position to obtain the relative phase φ = {φ r (x1)-φ s (x1),φ r x(2)-φ s x(2),..φ. r ,x i (φ) s -x i (, and perform phase unwrapping on the relative phase;

[0013] Step 5: setting an intensity threshold to distinguish the fiber Bragg grating area from the non-bracing area, and re-performing a linear fit on the phase of the grating interval area according to the phase of the grating area;

[0014] Step 6: Calculate the phase difference between every two adjacent data in the relative phase to obtain the differential relative phase Δφ={Δφ1, Δφ2, ..., Δφ i-1}={φ2-φ1,φ3-φ2,...,φ i -φi-1}, locate the position information of strain start and end according to the sudden change in the differential relative phase curve;

[0015] Step 7: Based on the sudden change in the differential relative phase curve, the entire optical fiber is spatially divided, and the strain magnitude obtained by the cross-correlation algorithm is matched with the spatial position to obtain the strain at each position of the optical fiber.

[0016] Preferably, the OFDR sensing system comprises: a tunable laser, a first coupler, an auxiliary interferometer, a main interferometer, a clock conditioning circuit, and a data acquisition card;

[0017] The tunable laser generates continuous light, which is divided into two paths through a first coupler, one path entering the auxiliary interferometer and the other entering the main interferometer;

[0018] In the auxiliary interferometer, the second coupler splits the light into two paths, one entering the delay optical path and the other entering the reference path. The two paths of light generate a beat frequency in the third coupler and are output to the first balanced detector, where they are converted into electrical signals. After passing through the clock conditioning circuit, they are used as an external clock for the data acquisition card to collect the main interferometer signal.

[0019] In the main interferometer, the fourth coupler splits the light into two paths, one entering the reference path and the other entering the optical fiber to be tested. The backscattered Rayleigh light scattered back by the circulator beats with the reference light inside the fifth coupler and is output to the second balanced detector, converted into an electrical signal, and output to the data acquisition card for collection.

[0020] Preferably, in the OFDR sensing system, the beat signal formed in the main interferometer is expressed as:

[0021]

[0022] where I(t) is the beat frequency signal, R(τ) is the reflection coefficient, E0 is the signal amplitude, τ = 2nz / c is the time delay at the scattering location, f0 is the initial light frequency, γ is the sweep rate of the light source, and ψ is the random phase term.

[0023] Preferably, in step 2, the two groups of signals are subjected to Fourier transform respectively to obtain the complex signals {a1+b1i,a2+b2i,...,a i +b i i}, where, a i 、b i represent the real and imaginary parts of the i-th complex signal respectively;

[0024] Then use the inverse tangent function to obtain the reference signal phase φ r and the measured signal phase φ s :

[0025] when a i When >0, the phase is expressed as

[0026] when a i <0 and b i When ≥0, the phase is expressed as

[0027] when a i <0 and b i When <0, the phase is expressed as

[0028] when a i = 0 and b i When >0, the phase is expressed as

[0029] when a i = 0 and b i When <0, the phase is expressed as

[0030] Preferably, in step 3, correcting the misalignment phenomenon in the optical fiber distance domain includes the following sub-steps:

[0031] Step 3.1, intercept the reference signal using a window of data length M, offset it to the left and right of the corresponding position of the measurement signal, and intercept several segments of the signal with the same data length;

[0032] Step 3.2: Perform an inverse fast Fourier transform on the intercepted signal segment, and use a cross-correlation algorithm to extract the cross-correlation spectrum between the reference signal scattering spectrum and the scattering spectrum of each measurement signal. Calculate the ratio of the main peak to the average value of the secondary peak of each cross-correlation spectrum. The reference signal segment and the measurement signal segment corresponding to the cross-correlation spectrum with the largest ratio are considered the two most matched signal segments. The misalignment amount is the number of points offset by the most matched measurement signal segment.

[0033] Step 3.3: Select the next reference signal segment and measurement signal segment, use the offset points of the previous measurement signal segment as the starting offset of the next measurement signal segment, add the accumulated offset points to the starting point of the next measurement signal segment, perform cross-correlation offset compensation, and achieve matching between the reference signal segment and the measurement signal segment;

[0034] Step 3.4: Repeat steps 3.1 to 3.3 to complete the correction of the distance domain misalignment phenomenon on the entire optical fiber.

[0035] Preferably, in step 3, the strain magnitude of the optical fiber at the position is obtained using a cross-correlation algorithm:

[0036]

[0037] Where m is the cross-correlation peak offset, M is the window width, S is the strain sensitivity of the optical fiber to be measured, and ΔF represents the frequency sweep range of the light source.

[0038] Preferably, in step 3 and step 7, the window to which the mutation position of the differential relative phase curve belongs is determined by the following method:

[0039] The differential relative phase corresponding to the kth window is {Δφ (k-1)M+1 ,Δφ (k-1)M+2 ,...,Δφ kM}, if the mutation occurs in the kth window, then Δφ (k-1)M+1 The strain at the mutation start position is assigned by the strain calculated in the k-1th window, and the mutation end position is assigned to Δφ kM The strain at the kth position is assigned by the strain calculated in the k+1th window, and the strain at other positions is directly assigned by the strain obtained by the cross-correlation algorithm.

[0040] The technical solution of the present invention further provides: an electronic device, comprising:

[0041] one or more processors;

[0042] a storage device having one or more programs stored thereon;

[0043] When the one or more programs are executed by the one or more processors, the one or more processors implement any of the above-mentioned optical frequency domain reflection strain sensing methods based on the combination of phase demodulation and cross-correlation.

[0044] The technical solution of the present invention also provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the program implements any step in the above-mentioned optical frequency domain reflection strain sensing method based on the combination of phase demodulation and cross-correlation.

[0045] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0046] 1. The present invention uses a cross-correlation algorithm to accurately match the reference signal and the measurement signal at the same position of the optical fiber to correct the distance domain misalignment phenomenon, thereby accurately calculating the differential relative phase and accurately identifying the location where the strain occurs.

[0047] 2. The present invention effectively avoids phase disturbances caused by environmental noise and system noise in the phase demodulation algorithm by combining the spatial positioning information of the phase demodulation algorithm with the strain magnitude information obtained by the cross-correlation algorithm, thereby improving the stability and anti-noise capability of the phase demodulation algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the OFDR sensing system of the present invention;

[0049] Figure 2 This is a flowchart of the optical frequency domain reflection strain sensing method of the present invention;

[0050] Figure 3 is a spectrum signal-distance diagram measured by an embodiment of the present invention;

[0051] Figure 4 is a positioning diagram based on phase demodulation according to an embodiment of the present invention;

[0052] Figure 5 3 is a graph of strain results measured in an embodiment of the present invention. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the application are further elaborated in detail below with reference to the accompanying drawings. The described embodiments are only a part of the embodiments involved in the present invention. All non-innovative embodiments of other researchers in this field on this embodiment fall within the scope of protection of the present invention. At the same time, the step numbers in the embodiments of the present invention are only set for the convenience of explanation and description, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0054] In one embodiment of the present invention, an OFDR sensing system is used to collect Rayleigh backscattering signals before and after strain. Figure 1 As shown, it includes: a tunable laser, a first coupler, a second coupler, a third coupler, a fourth coupler, a fifth coupler, a delay fiber, a circulator, an optical fiber to be tested, a first balanced detector, a second balanced detector, a clock conditioning circuit and a data acquisition card.

[0055] a tunable laser for generating continuous light to the first coupler;

[0056] A first coupler is used to split the light into two paths, one of which enters the auxiliary interferometer and the other enters the main interferometer;

[0057] The second coupler is used to split the light into two parts, one of which enters the delay optical path and the other enters the reference path. The two light paths generate a beat frequency in the third coupler and are then output to the first balanced detector.

[0058] The fourth coupler is used to split the light into two parts, one of which enters the reference path and the other enters the optical fiber under test. The scattered back Rayleigh scattered light and the reference light beat each other inside the fifth coupler and are then output to the second balanced detector.

[0059] a circulator, configured to input light from the first port and transmit it to the sensing optical fiber from the second port, and output the back Rayleigh scattered light from the third port to the fifth coupler;

[0060] Clock conditioning circuit, used to collect external clock of main interferometer signal;

[0061] Data acquisition card, used to collect the main interferometer signal and perform subsequent data processing.

[0062] Specifically, in this embodiment, a tunable laser outputs continuous light with a wavelength range of 1535-1565nm, an output power of 10mW, and a scanning rate of 70nm / s. This light is split into two paths through a first coupler: 90% is output to the main interferometer, and 10% is output to the auxiliary interferometer. 50% of the light from the second coupler enters the reference path, and 50% enters the delay path. Beat frequency interference occurs in a third coupler, where it is received by a first balanced detector and converted into an electrical signal. After passing through a clock conditioning circuit, this signal serves as an external clock for the data acquisition card to collect the main interferometer signal. A fourth coupler also generates 50% of the light from the reference path, and 50% of the light from the fourth coupler enters the optical fiber under test, which is engraved with a grating with a length of 5mm, a spacing of 5mm, and a total length of 1.8m. The scattered back Rayleigh scattered light and the reference light beat frequency within a fifth coupler, where it is received by a second balanced detector, converted into an electrical signal, and output to the data acquisition card for acquisition.

[0063] In this embodiment, the optical frequency domain reflection strain sensing method based on phase demodulation and cross-correlation is as follows: Figure 2 As shown, the implementation steps are as follows:

[0064] Step 1: Use a translation stage to apply strain to the optical fiber under test. Use the OFDR sensing system to collect two sets of Rayleigh backscattered signals before and after the strain is applied to the optical fiber under test. The signal length is 6300. One set is used as the reference signal {2543, 2541, ..., 1413}, and the other set is used as the measurement signal {1668, 1752, ..., 1907}.

[0065] Step 2: Perform Fourier transform on the two sets of signals collected in step 1. The complex form of the reference signal is {338498-424006i,-740944-215965i,...,-19905-71013i}, and the complex form of the measurement signal is {-198545+526285i,674805+71912i,...,-11966-9673i}. Use the inverse tangent function to obtain the reference signal phase {-0.8971,-2.8580,...,-1. and the measurement signal phase {1.9315,0.1062,...,-2.4618}.

[0066] Step 3: In this experiment, the window width is set to 65.

[0067] First, a signal segment containing 65 data points was captured from the reference signal. The maximum left-right offset of the corresponding position in the measured signal was set to 5 data points, and several signal segments of the same length were captured. These signal segments were then inverse-fast Fourier transformed to obtain the cross-correlation spectra of their respective scattering spectra. The maximum ratio of the primary peak to the secondary peak average was then found to achieve matching between the reference and measured signals.

[0068] In the 46th window, the matched measurement signal segment is offset to the right by 1 point. The offset point number of the 46th window is used as the starting misalignment of the measurement signal segment in the 47th window. On this basis, cross-correlation misalignment compensation is performed to achieve matching between the reference signal segment and the measurement signal segment.

[0069] By analogy, the distance domain misalignment phenomenon on the entire optical fiber is corrected, and strain demodulation processing is performed on the two matching signal segments to obtain the strain magnitude of the optical fiber at that position under the cross-correlation algorithm.

[0070] Step 4: Subtract the phases of the matched reference signal and the measured signal at the same position to obtain the relative phase {-2.8286, -2.9641, ..., 0.6177}, and then perform phase unwrapping.

[0071] Step 5: Figure 3 As shown, by setting the intensity threshold of -10, the fiber grating area and the non-grating area in the optical fiber to be tested are effectively distinguished, and the phase data on the non-grating area of the latter section are linearly fitted according to the phase distribution on the former section of the grating to achieve continuity correction of the phase information.

[0072] Step 6: Calculate the phase difference between each two adjacent data in the relative phase to obtain the differential relative phase {-0.1355, -0.4847, ..., -0.9845}, as shown in Figure 4 As shown in Figure 2, the strain location is accurately located based on the mutation position in the differential relative phase curve. The first mutation position is in the 41st window, and the second mutation position is in the 70th window, thus spatially dividing the entire fiber.

[0073] Step 7: The first mutation position is located in the 41st window. The strain from the starting position of the window to the starting position of the mutation is assigned by the strain calculated in the 40th window, and the strain from the end position of the mutation to the end position of the window is assigned by the strain calculated in the 42nd window. The second mutation position is located in the 70th window. The strain from the starting position of the window to the starting position of the mutation is assigned by the strain calculated in the 69th window, and the strain from the end position of the mutation to the end position of the window is assigned by the strain calculated in the 71st window. The strains at other positions are directly assigned by the strain obtained by the cross-correlation algorithm. The final strain curve is as follows: Figure 5 shown.

[0074] It can be seen that the optical frequency domain reflection strain sensing method based on the combination of phase demodulation and cross-correlation of the present invention can solve the problems of insufficient spatial resolution of existing strain demodulation technology and the influence of optical noise on phase demodulation, and accurately identify the location where strain occurs.

[0075] In an embodiment of the present invention, an electronic device is also provided, including: one or more processors; a storage device on which one or more programs are stored; when the one or more programs are executed by the one or more processors, the one or more processors implement the optical frequency domain reflection strain sensing method based on the combination of phase demodulation and cross-correlation described in any of the above embodiments.

[0076] In an embodiment of the present invention, a computer-readable storage medium is further provided, on which a computer program is stored. When the program is executed by a processor, the steps of any one of the optical frequency domain reflection strain sensing methods based on the combination of phase demodulation and cross-correlation in the above embodiments are implemented.

[0077] The above embodiments are merely preferred embodiments of the present invention, and their descriptions are relatively specific and detailed. However, the scope of protection of the present invention is not limited thereto. All technical solutions within the scope of protection of the present invention are within the scope of protection of the present invention. For those skilled in the art, various improvements and substitutions that do not depart from the scope of protection of the present invention should be considered as within the scope of protection of the present invention.

Claims

1. An optical frequency domain reflectometry strain sensing method based on phase demodulation and cross-correlation, characterized in that: The steps include: Step 1: Use the OFDR sensing system to collect two sets of Rayleigh backscattering signals before and after the optical fiber is strained, one set is the reference signal and the other set is the measurement signal; Step 2: Perform Fourier transform on the two sets of collected Rayleigh backscattered signals, extract phase information, obtain reference signal phase and measurement signal phase, perform modulo operation on the Fourier transformed phase information, and obtain a spectrum signal-distance map; Step 3: Using a cross-correlation algorithm, by comparing the matching degree of different signal segments near the same position in the spectrum signal-distance diagram, the best match between the reference signal and the measurement signal at the same position on the optical fiber is achieved. This corrects the misalignment phenomenon in the optical fiber distance domain and calculates the strain along the entire optical fiber. Step 4: Subtract the phases of the matched reference signal and the measured signal at the same position to obtain the relative phase, and perform phase unwrapping on the relative phase; Step 5: setting an intensity threshold to distinguish the fiber Bragg grating area from the non-bracing area, and re-performing a linear fit on the phase of the grating interval area according to the phase of the grating area; Step 6: Calculate the phase difference between every two adjacent data in the relative phase to obtain the differential relative phase. According to the sudden change in the differential relative phase curve, locate the position information of the start and end of the strain. Step 7: Based on the sudden change in the differential relative phase curve, the entire optical fiber is spatially divided, and the strain magnitude obtained by the cross-correlation algorithm is matched with the spatial position to obtain the strain at each position of the optical fiber.

2. The optical frequency domain reflection strain sensing method according to claim 1, characterized in that: The OFDR sensing system includes: a tunable laser, a first coupler, an auxiliary interferometer, a main interferometer, a clock conditioning circuit and a data acquisition card; The tunable laser generates continuous light, which is divided into two paths through a first coupler, one path entering the auxiliary interferometer and the other entering the main interferometer; In the auxiliary interferometer, the second coupler splits the light into two paths, one entering the delay optical path and the other entering the reference path. The two paths of light generate a beat frequency in the third coupler and are output to the first balanced detector, where they are converted into electrical signals. After passing through the clock conditioning circuit, they are used as an external clock for the data acquisition card to collect the main interferometer signal. In the main interferometer, the fourth coupler splits the light into two paths, one entering the reference path and the other entering the optical fiber to be tested. The backscattered Rayleigh light scattered back by the circulator beats with the reference light inside the fifth coupler and is output to the second balanced detector, converted into an electrical signal, and output to the data acquisition card for collection.

3. The optical frequency domain reflection strain sensing method according to claim 2, characterized in that: The beat signal formed in the main interferometer is expressed as: where I(t) is the beat frequency signal, R(τ) is the reflection coefficient, E0 is the signal amplitude, τ is the time delay at the scattering location, f0 is the initial light frequency, γ is the sweep rate of the light source, and ψ is the random phase term.

4. The optical frequency domain reflection strain sensing method according to claim 1, characterized in that: In step 2, the two sets of signals are Fourier transformed to obtain the complex signals {a1+b1i,a2+b2i,...,a i +b i i}; Among them, a i 、b i represent the real and imaginary parts of the i-th complex signal respectively; Then, the inverse tangent function is used to obtain the reference signal phase and the measurement signal phase respectively; when a i When >0, the phase is expressed as when a i <0 and b i When ≥0, the phase is expressed as when a i <0 and b i When <0, the phase is expressed as when a i = 0 and b i When >0, the phase is expressed as when a i = 0 and b i When <0, the phase is expressed as 5. The optical frequency domain reflection strain sensing method according to claim 4, characterized in that: In step 3, the misalignment phenomenon in the optical fiber distance domain is corrected, including the following sub-steps: Step 3.1, intercept the reference signal using a window of data length M, offset it to the left and right of the corresponding position of the measurement signal, and intercept several segments of the signal with the same data length; Step 3.2: Perform an inverse fast Fourier transform on the intercepted signal segment, and use a cross-correlation algorithm to extract the cross-correlation spectrum between the reference signal scattering spectrum and the scattering spectrum of each measurement signal. Calculate the ratio of the main peak to the average value of the secondary peak of each cross-correlation spectrum. The reference signal segment and the measurement signal segment corresponding to the cross-correlation spectrum with the largest ratio are considered the two most matched signal segments. The misalignment amount is the number of points offset by the most matched measurement signal segment. Step 3.3: Select the next reference signal segment and measurement signal segment, use the offset points of the previous measurement signal segment as the starting offset of the next measurement signal segment, add the accumulated offset points to the starting point of the next measurement signal segment, perform cross-correlation offset compensation, and achieve matching between the reference signal segment and the measurement signal segment; Step 3.4: Repeat steps 3.1 to 3.3 until the distance domain misalignment on the entire optical fiber is corrected.

6. The optical frequency domain reflection strain sensing method according to claim 5, characterized in that: In step 3, strain demodulation is performed on the two most matching signal segments to obtain the strain magnitude of the optical fiber at the positions of the two most matching signal segments under the cross-correlation algorithm: Where m is the cross-correlation peak offset, M is the window width, S is the strain sensitivity of the optical fiber to be measured, and ΔF represents the frequency sweep range of the light source.

7. The optical frequency domain reflection strain sensing method according to claim 5, characterized in that: The reference signal phase is φ r , the measurement signal phase is represented by φ s : f r ={φ r (x1),φ r (x2),...,φ r (x i )} f s ={φ s (x1),φ s (x2),...,φ s (x i )} The relative phase is denoted as φ: φ={φ r (x1)-φ s (x1),φ r (x2)-φ s (x2),...,φ r (x i )-φ s (x i )} The differential relative phase is expressed as Δφ: Δφ={Δφ1,Δφ2,...,Δφ i-1 }={φ2-φ1,φ3-φ2,...,φ i -f i-1 } Among them, x i is the position of the i-th sampling point.

8. The optical frequency domain reflection strain sensing method according to claim 7, characterized in that: In step 7, the window to which the mutation position of the differential relative phase curve belongs is determined as follows: The differential relative phase corresponding to the kth window is {Δφ (k-1)M+1 ,Δφ (k-1)M+2 ,...,Δφ kM }, if the mutation occurs in the kth window, then Δφ (k-1)M+1 The strain at the mutation start position is assigned by the strain calculated in the k-1th window, and the mutation end position is assigned to Δφ kM The strain at the kth position is assigned by the strain calculated in the k+1th window, and the strain at other positions is directly assigned by the strain obtained by the cross-correlation algorithm.

9. An electronic device, characterized in that: include: one or more processors; a storage device having one or more programs stored thereon; When the one or more programs are executed by the one or more processors, the one or more processors implement the optical frequency domain reflection strain sensing method based on the combination of phase demodulation and cross-correlation as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that A computer program is stored thereon, and when the program is executed by a processor, the steps of the optical frequency domain reflection strain sensing method based on the combination of phase demodulation and cross-correlation according to any one of claims 1 to 8 are implemented.

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