Demodulation method and demodulation system of optical fiber Fabry-Perot sensor

Abstract

The invention relates to a demodulation method and demodulation system of an optical fiber Fabry-Perot sensor, and the demodulation method comprises the steps: obtaining an initial optical path of each chamber, the initial optical path of each chamber representing an optical path required for a light beam to go back and forth in each chamber before the optical fiber Fabry-Perot sensor is used; obtaining a preset number of measurement light beams reflected by the optical fiber Fabry-Perot sensor; calculating a target phase of each measuring light beam corresponding to each chamber based on the target optical path of each chamber and the central wavelength of the preset number of measuring light beams, wherein the initial value of the target optical path of each chamber is the initial optical path of each chamber; based on the light intensity of each measuring light beam and the target phase of each measuring light beam corresponding to each chamber, calculating the variation of a target optical path; and the variable quantity corresponding to each chamber is measured. According to the invention, the demodulation method and demodulation system for demodulating the optical fiber Fabry-Perot sensor of each chamber can be provided.

Description

Technical Field

[0001] The present disclosure relates to the field of electronic core industries, and particularly to a demodulation method and a demodulation system for a fiber optic Fabry-Perot sensor. Background Art

[0002] Fiber optic Fabry-Perot sensors have the advantages of anti-electromagnetic interference, high temperature resistance, small size, high sensitivity, and fast response speed, and are widely used in fields such as coal mine exploration, oil well monitoring, and aerospace. Fiber optic Fabry-Perot sensors can be divided into single-cavity fiber optic Fabry-Perot sensors and multi-cavity fiber optic Fabry-Perot sensors according to the number of Fabry-Perot cavities included in parallel cascades. Among them, single-cavity fiber optic Fabry-Perot sensors can be called fiber optic Fabry-Perot single-cavity sensors, and multi-cavity fiber optic Fabry-Perot sensors can be called fiber optic Fabry-Perot multi-cavity sensors. In the application process, fiber optic Fabry-Perot sensors often need to measure multiple parameters simultaneously to determine the state of the target. For example, when detecting the working conditions of an oil well or the state of an aero-engine, parameters such as temperature, pressure, or vibration need to be measured simultaneously. Currently, each cavity of a fiber optic Fabry-Perot multi-cavity sensor or each cavity of multiple series-connected fiber optic Fabry-Perot single-cavity sensors can be used to measure different parameters, so as to achieve the measurement of multiple parameters.

[0003] In the prior art, the fiber optic Fabry-Perot multi-cavity sensor can be demodulated by the wavelength method, such as the dual-wavelength method and the triple-wavelength method. The dual-wavelength method and the triple-wavelength method use mathematical operations between two or three wavelengths to obtain an orthogonal signal containing the cavity information of the fiber optic Fabry-Perot multi-cavity sensor, and extract the phase information of the orthogonal signal, thereby achieving demodulation.

[0004] However, the wavelength methods provided by the prior art can either only demodulate single-cavity fiber optic Fabry-Perot sensors or only demodulate specific cavities in fiber optic Fabry-Perot multi-cavity sensors, such as the shortest cavity in a fiber optic Fabry-Perot multi-cavity sensor. Therefore, how to use wavelength demodulation for each cavity of a fiber optic Fabry-Perot multi-cavity sensor and each cavity of multiple series-connected fiber optic Fabry-Perot single-cavity sensors remains to be studied. Summary of the Invention

[0005] The present disclosure is made in view of the above circumstances, and its purpose is to provide a demodulation method and a demodulation system for a fiber optic Fabry-Perot sensor that can demodulate each cavity.

[0006] To this end, a first aspect of the present disclosure provides a demodulation method for a fiber optic Fabry-Perot sensor. The fiber optic Fabry-Perot sensor is used to measure a measured quantity and includes a fiber optic Fabry-Perot single cavity sensor and a fiber optic Fabry-Perot multi-cavity sensor. The fiber optic Fabry-Perot single cavity sensor includes a single chamber, and the fiber optic Fabry-Perot sensor includes a plurality of chambers connected in parallel. The demodulation method is used to demodulate each chamber of a plurality of the fiber optic Fabry-Perot single cavity sensors connected in series or each chamber of the plurality of chambers of the fiber optic Fabry-Perot multi-cavity sensor and includes: obtaining an initial optical path of each chamber, where the initial optical path of each chamber represents the optical path required for a light beam to make a round trip in each chamber before using the fiber optic Fabry-Perot sensor; obtaining a preset number of measured light beams reflected by the fiber optic Fabry-Perot sensor, where the preset number satisfies a preset relationship with the total number of each chamber, and the central wavelengths of the preset number of measured light beams are different from each other; calculating a target phase of each measured light beam corresponding to each chamber based on the target optical path of each chamber and the central wavelengths of the preset number of measured light beams, where the initial value of the target optical path of each chamber is the initial optical path of each chamber; determining a target matrix based on the light intensity of each measured light beam and the target phase of each measured light beam corresponding to each chamber, calculating a change amount of each chamber corresponding to the target optical path based on the target matrix, where at least one of the dimensions of the rows and columns of the target matrix is the preset number; and obtaining the measured quantity based on the change amount corresponding to each chamber.

[0007] In the present disclosure, each chamber has a corresponding target phase with respect to measured light beams of different central wavelengths. The number of measured light beams satisfies a preset relationship with the total number of each chamber, and the light intensity of the measured light beams reflected by the fiber optic Fabry-Perot sensor includes the change of the target optical path of each chamber under the action of the measured quantity. Through the target matrix determined based on the light intensity of each measured light beam and the target phase of each measured light beam corresponding to each chamber, the change amount of each chamber corresponding to the target optical path can be calculated, and thus each chamber of the fiber optic Fabry-Perot sensor can be demodulated. In addition, the number of measured light beams satisfies a preset relationship with the total number of each chamber, which can make the number of measured light beams adapt to the change in the number of chambers. Therefore, when the number of chambers increases, more information of the measured light beams can be used to demodulate each chamber, and thus the accuracy of demodulating each chamber can be improved.

[0008] In addition, in the demodulation method of the fiber optic Fabry-Perot sensor according to the first aspect of the present disclosure, optionally, the target phase of each measured light beam corresponding to each chamber satisfies the formula: θ ij = 2π * S i / λ j , where i represents the index of each chamber, j represents the index of the preset number of measured light beams, S i represents the target optical path of the i-th chamber, and λ jrepresents the central wavelength of the j-th measurement light beam, θ ij represents the target phase of the j-th measurement light beam corresponding to the i-th chamber. In this case, if the target optical paths of each chamber and the central wavelengths of each measurement light beam are known, the target phases of each measurement light beam corresponding to each chamber can be conveniently calculated through the mathematical relationship between the two.

[0009] In addition, in the demodulation method of the fiber optic Fabry-Perot sensor according to the first aspect of the present disclosure, optionally, the preset relationship satisfies the formula:

[0010] m = n 2 + n + 1,

[0011] where n represents the total number of each chamber, and m represents the preset number. Thus, measurement light beams with different central wavelengths sufficient to meet the calculation requirements can be obtained.

[0012] In addition, in the demodulation method of the fiber optic Fabry-Perot sensor according to the first aspect of the present disclosure, optionally, calculating the change amount corresponding to each chamber includes: constructing a first matrix, the elements of which are the light intensities of the preset number of measurement light beams; constructing a second matrix, the order of which is the preset number and the elements of which are related to the target phases of each measurement light beam corresponding to each chamber; multiplying the inverse matrix of the second matrix and the first matrix to determine the target matrix; obtaining the target phase difference of each chamber based on the target matrix; and calculating the change amount corresponding to each chamber based on the target phase difference of each chamber. In this case, the target matrix determined by multiplying the inverse matrix of the second matrix and the first matrix can establish the correlation between the light intensities of the preset number of measurement light beams and the target phases of each measurement light beam corresponding to each chamber, thereby improving the accuracy of calculating the change amount of the relative target optical path corresponding to each chamber from the target matrix.

[0013] In addition, in the demodulation method of the fiber optic Fabry-Perot sensor according to the first aspect of the present disclosure, optionally, the second matrix satisfies the formula:

[0014]

[0015] , where A represents the second matrix, θ nmIt represents the target phase of the m-th measurement beam corresponding to the n-th chamber. In this case, the second matrix includes the DC component representing the signal of the measurement beam (i.e., the first column of the second matrix), the sine and cosine values of the target phases of the measurement beams corresponding to a single chamber, and the sine and cosine values of the sum of the target phases of the measurement beams corresponding to multiple chambers. When calculating the change amount of each chamber, the interference situation between the measurement beams reflected by different chambers of the fiber Fabry-Perot sensor can be fully considered, thereby further improving the accuracy of demodulating each chamber.

[0016] In addition, in the demodulation method of the fiber Fabry-Perot sensor according to the first aspect of the present disclosure, optionally, the target phase differences of each chamber satisfy the formula:

[0017]

[0018] where i represents the index of each chamber, and Δθ i represents the target phase difference of the i-th chamber, A -1 represents the inverse matrix of the second matrix, and I represents the first matrix. Thus, the target phase differences of each chamber can be conveniently calculated through the formula.

[0019] In addition, in the demodulation method of the fiber Fabry-Perot sensor according to the first aspect of the present disclosure, optionally, the target phase differences of each chamber are corrected based on the correction value and the target phase differences of each chamber at different times. The correction value is π, and the correction includes: if the difference between the target phase difference of each chamber at the current moment and the target phase difference at the next moment is greater than the first preset value, then the target phase differences of each chamber later than the current moment are all added with the correction value; and if the difference between the target phase difference of each chamber at the current moment and the target phase difference at the next moment is less than the second preset value, then the target phase differences of each chamber later than the current moment are all subtracted by the correction value. In this case, since the principal value range of the target phase difference obtained by using the arctangent algorithm is from -π / 2 to π / 2, when the target phase difference of each chamber exceeds this principal value range, a phase jump will occur. At this time, by correcting the target phase difference of each chamber, a more accurate target phase difference can be obtained.

[0020] In addition, in the demodulation method of the fiber optic Fabry-Perot sensor according to the first aspect of the present disclosure, optionally, the target optical path of each chamber is re-determined based on the change amount corresponding to each chamber and the target optical path of each chamber. Re-determining the target optical path of each chamber includes: if the absolute value of the change amount corresponding to each chamber is less than a preset threshold, the target optical path of each chamber remains unchanged; and if the absolute value of the change amount corresponding to each chamber is greater than the preset threshold, the target optical path of each chamber after re-determination is made equal to the sum of the target optical path of each chamber before re-determination and the change amount corresponding to each chamber. In this case, when the current change amount corresponding to each chamber is small, keeping the target optical path of each chamber unchanged can control the error within the desired range while reducing the computational amount. When the current change amount corresponding to each chamber is large, re-using the current change amount corresponding to each chamber to determine the target optical path of each chamber can still control the error within the desired range in the subsequent calculation process.

[0021] In addition, in the demodulation method of the fiber optic Fabry-Perot sensor according to the first aspect of the present disclosure, optionally, obtaining the initial optical path of each chamber includes: obtaining the white light interference spectrum of the fiber optic Fabry-Perot sensor based on the light beam; performing Fourier transform on the white light interference spectrum to obtain the spectrum corresponding to the white light interference spectrum; filtering the spectrum to obtain multiple sub-spectra corresponding to each chamber; filtering the white light interference spectrum according to the multiple sub-spectra to obtain multiple sub-spectra corresponding to each chamber; and performing peak-to-peak operation on the multiple sub-spectra respectively to obtain the initial optical path of each chamber. In this case, when the refractive index and cavity length of each chamber of the fiber optic Fabry-Perot sensor are unknown, or it is inconvenient to directly obtain the refractive index and cavity length of each chamber, the initial optical path of each chamber can be obtained more conveniently.

[0022] The second aspect of the present disclosure provides a demodulation system for a fiber optic Fabry-Perot sensor, including: the fiber optic Fabry-Perot sensor, a transmitting module, a connecting module, a filtering module, and a processing module. The transmitting module emits a light beam, and the light beam is incident on the fiber optic Fabry-Perot sensor through the connecting module. The fiber optic Fabry-Perot sensor reflects the light beam, and the reflected light beam is input into the filtering module through the connecting module. The filtering module outputs multiple light beams with different central wavelengths, and the processing module executes the demodulation method of the fiber optic Fabry-Perot sensor according to the first aspect of the present disclosure based on the multiple light beams output by the filtering module. Thus, each chamber of the fiber optic Fabry-Perot sensor can be demodulated.

[0023] According to the present disclosure, a demodulation method and a demodulation system for a fiber optic Fabry-Perot sensor capable of demodulating each chamber can be provided. Description of the Drawings

[0024] The present disclosure will now be further explained in detail only by way of examples with reference to the accompanying drawings, where:

[0025] Figure 1 is a schematic diagram showing an embodiment of the fiber optic Fabry-Perot sensor involved in the examples of the present disclosure.

[0026] Figure 2 is a flowchart showing the demodulation method involved in the examples of the present disclosure.

[0027] Figure 3A is a flowchart showing the process of obtaining the initial optical path of each chamber involved in the examples of the present disclosure; Figure 3B is a schematic diagram showing the 3dB bandwidth involved in the examples of the present disclosure.

[0028] [[ID=

[17] Figure 4 is a flowchart showing the process of calculating the change amount corresponding to each chamber involved in the examples of the present disclosure.

[0029] Figure 5 is a flowchart showing the process of correcting the target phase difference of each chamber involved in the examples of the present disclosure.

[0030] Figure 6 is a schematic diagram showing the correction of the target phase difference of each chamber involved in the examples of the present disclosure.

[0031] Figure 7 is a flowchart showing the process of re-determining the target optical path of each chamber involved in the examples of the present disclosure.

[0032] Figure 8 is a block diagram of the demodulation system involved in the examples of the present disclosure.

[0033] Figure 9 is a schematic diagram showing the structure of the connection module involved in the examples of the present disclosure. Detailed Embodiments

[0034] Hereinafter, with reference to the accompanying drawings, the preferred embodiments of the present disclosure will be described in detail. In the following description, the same reference numerals are given to the same components, and repeated descriptions are omitted. In addition, the drawings are only schematic diagrams, and the ratio of the sizes of the components to each other or the shapes of the components may be different from the actual ones.

[0035] In addition, the subheadings and the like involved in the following description of the present disclosure are not intended to limit the content or scope of the present disclosure, and they are only for the purpose of providing a reading hint. Such subheadings should neither be understood as being used to divide the content of the article, nor should the content under the subheadings be limited only to the scope of the subheadings.

[0036] It should be noted that there seems to be a formatting issue with the tag "

[17] " in the original text. It is translated as " Figure 4 " as it is, but it might be an incorrect or inconsistent tag in the original context. If this is an error, it should be corrected in the source material for a more accurate translation and understanding.The present disclosure provides a demodulation method for a fiber optic Fabry-Perot sensor (hereinafter may be simply referred to as the demodulation method), and the fiber optic Fabry-Perot sensor can be used to measure a measured quantity. In some examples, the fiber optic Fabry-Perot sensor may include a fiber optic Fabry-Perot single cavity sensor and a fiber optic Fabry-Perot multi-cavity sensor. The fiber optic Fabry-Perot single cavity sensor involved in the present disclosure refers to a fiber optic Fabry-Perot sensor including a single Fabry-Perot cavity. The fiber optic Fabry-Perot multi-cavity sensor involved in the present disclosure refers to a fiber optic Fabry-Perot sensor including a plurality of Fabry-Perot cavities connected in parallel and in series. The Fabry-Perot cavity involved in the present disclosure may be simply referred to as a cavity. Through the demodulation method provided by the present disclosure, each cavity of the fiber optic Fabry-Perot sensor can be demodulated. Each cavity of the fiber optic Fabry-Perot sensor involved in the present disclosure refers to each cavity of a plurality of fiber optic Fabry-Perot single cavity sensors connected in series or each cavity of a plurality of cavities of a fiber optic Fabry-Perot multi-cavity sensor. The total number of each cavity involved in the present disclosure refers to the total number of each cavity of a plurality of fiber optic Fabry-Perot single cavity sensors connected in series or the total number of each cavity connected in parallel and in series in the fiber optic Fabry-Perot multi-cavity sensor.

[0037] The measured quantity involved in the present disclosure may refer to parameters such as temperature, pressure, or vibration in the environment where the fiber optic Fabry-Perot sensor is located.

[0038] The demodulation method for the fiber optic Fabry-Perot sensor involved in the present disclosure may also be referred to as a method for demodulating a fiber optic Fabry-Perot sensor and a demodulation method for obtaining a measured quantity based on a fiber optic Fabry-Perot sensor, etc. The demodulation method involved in the present disclosure can be applied to any application scenario where it is necessary to demodulate a fiber optic Fabry-Perot sensor to obtain a measured quantity.

[0039] Hereinafter, with reference to the accompanying drawings, the demodulation method involved in the present disclosure will be described in detail.

[0040] Figure 1 FIG. is a schematic diagram showing an embodiment of a fiber optic Fabry-Perot sensor 10 involved in an example of the present disclosure. Among them, Figure 1 FIG. shows a case where the total number of each cavity of the fiber optic Fabry-Perot sensor 10 is two.

[0041] In some examples, referring to Figure 1 , the fiber optic Fabry-Perot sensor 10 may include at least three reflecting surfaces. Specifically, the fiber optic Fabry-Perot sensor 10 may include a first reflecting surface 11, a second reflecting surface 12, and a third reflecting surface 13.

[0042] In some examples, the first reflecting surface 11, the second reflecting surface 12, and the third reflecting surface 13 may be parallel to each other. In some examples, any two reflecting surfaces may form a Fabry - Perot cavity (Fabry - Perot interference cavity, Fabry - Perot cavity). For example, the first reflecting surface 11 and the second reflecting surface 12 may form a first chamber, the second reflecting surface 12 and the third reflecting surface 13 may form a second chamber, and the first reflecting surface 11 and the third reflecting surface 13 may form a mixed chamber. Among them, the first chamber and the second chamber are two parallel - cascaded chambers. In the present disclosure, there is no inclusion relationship between the parallel - cascaded chambers.

[0043] In some examples, each chamber may respectively have a corresponding refractive index and cavity length. The refractive index of the chamber may refer to the refractive index of the medium in the chamber. The cavity length of the chamber may refer to the distance between the two reflecting surfaces that form the chamber.

[0044] In some examples, referring to Figure 1 , the fiber - optic Fabry - Perot sensor 10 can receive a light beam and reflect and transmit the light beam. In some examples, when the fiber - optic Fabry - Perot sensor 10 receives a light beam, the light beam may first reach the first reflecting surface 11. After the light beam reaches the first reflecting surface 11, the first reflecting surface 11 can reflect and transmit the light beam.

[0045] In some examples, referring to Figure 1 , the light beam transmitted by the first reflecting surface 11 may reach the second reflecting surface 12. After the transmitted light beam reaches the second reflecting surface 12, the second reflecting surface 12 can reflect and transmit the light beam.

[0046] In some examples, referring to Figure 1 , the light beam transmitted by the second reflecting surface 12 may reach the third reflecting surface 13. After the transmitted light beam reaches the third reflecting surface 13, the third reflecting surface 13 can reflect the light beam.

[0047] In some examples, an interference phenomenon may occur between the light beams reflected by the first reflecting surface 11, the second reflecting surface 12, and the third reflecting surface 13. The interference phenomenon may be related to the refractive index and cavity length of the chamber. In this case, when the measured quantity acts on the fiber - optic Fabry - Perot sensor 10, it may cause a change in the refractive index or cavity length of the chamber. That is to say, if the refractive index or cavity length of the chamber changes, the interference phenomenon between the reflected light beams will also change. By analyzing the interference phenomenon (i.e., demodulation), the change in the refractive index or cavity length of the chamber can be obtained, and the change in the refractive index or cavity length of the chamber can reflect the change in the measured quantity. Thus, the fiber - optic Fabry - Perot sensor 10 can be demodulated.

[0048] The demodulation method provided by the present disclosure can demodulate the fiber - optic Fabry - Perot sensor 10 to obtain the change in the measured quantity.

[0049] Figure 2 It is a flowchart showing the demodulation method involved in the examples of the present disclosure.

[0050] In some examples, referring to Figure 2 , the demodulation method may include: obtaining the initial optical path of each chamber (step S100); obtaining a preset number of measurement beams reflected by the fiber optic Fabry-Perot sensor 10 (step S200); calculating the target phase of each measurement beam corresponding to each chamber based on the target optical path of each chamber and the central wavelength of the preset number of measurement beams (step S300); determining a target matrix based on the light intensity of each measurement beam and the target phase of each measurement beam corresponding to each chamber, and calculating the change amount of the relative target optical path corresponding to each chamber based on the target matrix (step S400); and obtaining the measured quantity based on the change amounts of each chamber (step S500).

[0051] As described above, the demodulation method may include: obtaining the initial optical path of each chamber (step S100).

[0052] In some examples, in step S100, the initial optical path of each chamber may represent the optical path required for a beam to make a round trip in each chamber before using the fiber optic Fabry-Perot sensor 10. The optical path required for a beam to make a round trip in each chamber may refer to the optical path required for the beam to travel from the reflecting surface at one end of the chamber to the reflecting surface at the other end of the chamber and then back to the reflecting surface at one end of the chamber.

[0053] In some examples, in step S100, the initial optical path of each chamber may be obtained based on the refractive index and the chamber length of each chamber. Thus, when the refractive index and the chamber length of each chamber of the fiber optic Fabry-Perot sensor 10 are known, it is convenient to obtain the initial optical path of each chamber.

[0054] In some examples, the initial optical path of each chamber may satisfy formula 1:

[0055]

[0056] where i represents the index of each chamber, represents the initial optical path of the i-th chamber, n i represents the refractive index of the i-th chamber, l i represents the chamber length of the i-th chamber.

[0057] In some examples, in step S100, the initial optical path of each chamber may be obtained based on the white light interference spectrum of the fiber optic Fabry-Perot sensor 10.

[0058] Figure 3Ais a flowchart showing the acquisition of the initial optical paths of respective chambers involved in the examples of the present disclosure; Figure 3B is a schematic diagram showing the 3dB bandwidth involved in the examples of the present disclosure.

[0059] In some examples, referring to Figure 3A , the acquisition of the initial optical paths of respective chambers may include: obtaining the white light interference spectrum of the fiber Fabry - Perot sensor 10 (step S110); obtaining the spectrum corresponding to the white light interference spectrum based on the white light interference spectrum (step S120); obtaining a plurality of sub - spectra corresponding to respective chambers (step S130); obtaining a plurality of sub - spectra corresponding to respective chambers (step S140); and performing peak - to - peak operations on the plurality of sub - spectra respectively to acquire the initial optical paths of respective chambers (step S150). In this case, when the refractive indices and chamber lengths of respective chambers of the fiber Fabry - Perot sensor 10 are unknown, or it is inconvenient to directly obtain the refractive indices and chamber lengths of respective chambers, the initial optical paths of respective chambers can be acquired more conveniently.

[0060] In some examples, in step S110, the light source may emit a light beam and the light beam may be incident on the fiber Fabry - Perot sensor 10. The light source may be a white light source. Thus, it is convenient to obtain the white light interference spectrum of the fiber Fabry - Perot sensor 10. In some examples, the light source may also be a light source of other colors.

[0061] In some examples, in step S110, the white light interference spectrum of the fiber Fabry - Perot sensor 10 may be obtained based on the light beam.

[0062] In some examples, in step S110, the light beam reflected by the fiber Fabry - Perot sensor 10 may be received to obtain the white light interference spectrum of the fiber Fabry - Perot sensor 10.

[0063] In some examples, in step S120, the white light interference spectrum may be Fourier - transformed to obtain the spectrum corresponding to the white light interference spectrum. Thus, it is convenient to obtain the spectrum corresponding to the white light interference spectrum.

[0064] In some examples, the spectrum corresponding to the white light interference spectrum may have a plurality of wave peaks corresponding to respective chambers.

[0065] In some examples, in step S130, the spectrum may be filtered to obtain a plurality of sub - spectra corresponding to respective chambers. In some examples, a filter may be used and the spectrum may be filtered according to the frequency bands where the wave peaks corresponding to respective chambers are located. Thus, it is convenient to obtain a plurality of sub - spectra corresponding to respective chambers.

[0066] In some examples, in step S140, the white light interference spectrum may be filtered according to the plurality of sub - spectra to obtain a plurality of sub - spectra corresponding to respective chambers.

[0067] In some examples, in step S150, peak-to-peak operations may be performed on multiple sub-spectra respectively to obtain the initial optical paths of the respective chambers.

[0068] In some examples, in step S150, the peaks of the sub-spectra corresponding to the respective chambers may correspond to two wavelengths, and multiple valleys may be included between the two wavelengths.

[0069] In some examples, the initial optical paths of the respective chambers may satisfy Equation 2:

[0070]

[0071] where λ a and λ b respectively represent the two wavelengths corresponding to the peaks of the sub-spectra corresponding to the i-th chamber, and λ b is greater than λ a ; k represents the number of valleys included between the two wavelengths.

[0072] As described above, the demodulation method may further include: obtaining a preset number of measurement beams reflected by the fiber optic Fabry-Perot sensor 10 (step S200).

[0073] In some examples, in step S200, the light source may emit measurement beams and the measurement beams may be incident on the fiber optic Fabry-Perot sensor 10. The fiber optic Fabry-Perot sensor 10 may reflect the incident measurement beams.

[0074] In some examples, in step S200, the measurement beams reflected by the fiber optic Fabry-Perot sensor 10 may be input into an optical filter, and the optical filter may output a preset number of measurement beams. The central wavelengths of the respective measurement beams in the preset number of measurement beams may be within a preset wavelength range.

[0075] Figure 3B In some examples, in step S200, the central wavelengths of the preset number of measurement beams may be different from each other. In some examples, the optical filter may include multiple channels. Each channel of the optical filter may have a different 3 dB bandwidth. Refer to , the 3 dB bandwidth may be the wavelength range defined when the highest point of the power spectral density of each channel of the optical filter drops to 1 / 2. Thus, it is possible to facilitate the output of measurement beams with different central wavelengths.

[0076] In some examples, in step S200, the preset number and the total number of the respective chambers may satisfy a preset relationship. The preset relationship may satisfy Equation 3:

[0077] m = n 2 + n + 1… Equation 3

[0078] Among them, n represents the total number of each chamber, and m represents the preset quantity. Thus, measurement beams with different central wavelengths sufficient to meet the calculation requirements can be obtained.

[0079] In the present disclosure, when the preset quantity is m, the central wavelengths of the m obtained measurement beams can be λ1, λ2... λ m , and the light intensities of the m obtained measurement beams can be I1, I2... I m . Among them, λ m is the central wavelength of the m-th measurement beam, and I m is the light intensity of the m-th measurement beam.

[0080] In the present disclosure, it can be seen from Equation 3 that when the total number of each chamber is two, the number of measurement beams can be seven.

[0081] As described above, the demodulation method may further include: calculating the target phase of each measurement beam corresponding to each chamber based on the target optical path of each chamber and the central wavelengths of the preset number of measurement beams (step S300).

[0082] In the present disclosure, the target phase of each measurement beam corresponding to each chamber is the phase when each measurement beam is reflected from each chamber and interferes.

[0083] In some examples, in step S300, the initial value of the target optical path of each chamber may be the initial optical path of each chamber.

[0084] In some examples, in step S300, the target phase of each measurement beam corresponding to each chamber may satisfy Equation 4:

[0085] θ ij = 2π * S i / λ j ... Equation 4

[0086] Among them, i represents the index of each chamber, j represents the index of the preset number of measurement beams, S i represents the target optical path of the i-th chamber, λ j represents the central wavelength of the j-th measurement beam, and θ ij represents the target phase of the j-th measurement beam corresponding to the i-th chamber. In this case, if the target optical path of each chamber and the central wavelengths of each measurement beam are known, the target phase of each measurement beam corresponding to each chamber can be conveniently calculated through the mathematical relationship between the two.

[0087] As described above, the demodulation method may further include: determining a target matrix based on the light intensity of each measurement light beam and the target phase of each measurement light beam corresponding to each chamber, and calculating the change amount of the relative target optical path corresponding to each chamber based on the target matrix (step S400).

[0088] In some examples, in step S400, at least one dimension of the rows and columns of the target matrix may be a preset number. For example, when the preset number is m, the target matrix may include m rows or m columns.

[0089] Figure 4 It is a flowchart showing the calculation of the change amount corresponding to each chamber involved in the examples of the present disclosure.

[0090] In some examples, referring to Figure 4 , calculating the change amount corresponding to each chamber may include: constructing a first matrix (step S410); constructing a second matrix (step S420); multiplying the inverse matrix of the second matrix and the first matrix to determine the target matrix (step S430); obtaining the target phase difference of each chamber based on the target matrix (step S440); and calculating the change amount corresponding to each chamber based on the target phase difference of each chamber (step S450). In this case, the target matrix determined by multiplying the inverse matrix of the second matrix and the first matrix can establish the correlation between the light intensity of a preset number of measurement light beams and the target phase of each measurement light beam corresponding to each chamber, thereby improving the accuracy of calculating the change amount of the relative target optical path corresponding to each chamber by the target matrix.

[0091] In some examples, in step S410, the elements of the first matrix may be the light intensities of a preset number of measurement light beams. In some examples, the first matrix may satisfy formula 5:

[0092] I = [I1 I2 … I m T … Formula 5 where I represents the first matrix, and I m represents the light intensity of the m-th measurement light beam.

[0093] In some examples, if the preset number is m, the first matrix may be an m×1 order matrix.

[0094] In some examples, in step S420, the second matrix may be a square matrix.

[0095] In some examples, in step S420, the order of the second matrix may be a preset number. For example, if the preset number is m, the second matrix may be an m×m order matrix, that is, the second matrix may be an m-order square matrix.

[0096] ​In some examples, the elements of the second matrix can be related to the target phase of each measurement beam corresponding to each chamber. In some examples, the second matrix can satisfy Equation 6:

[0097]

[0098] In formula 6,

[0099] α1=[1 1 … 1] T ;

[0100] α2=[cos(θ 11 ) cos(θ 12 ) … cos(θ 1m )] T ;

[0101] α3=[sin(θ 11 ) sin(θ 12 ) … sin(θ 1m )] T ;

[0102] α 2n =[cos(θ n1 ) cos(θ n2 ) … cos(θ nm )] T ;

[0103] α 2n+1 =[sin(θ n1 ) sin(θ n2 ) … sin(θ nm )] T ;

[0104] α 2n+2 =[cos(θ 11 +θ 21 ) cos(θ 12 +θ 22 ) … cos(θ 1m +θ 2m )] T ;

[0105] α 2n+3 =[sin(θ 11 +θ 21 ) sin(θ 11 +θ 21 ) … sin(θ 1m +θ 2m )] T ;

[0106]

[0107]

[0108] To more clearly illustrate the pattern among the column numbers of the second matrix, the 2n + 4th, 2n + 5th, 2n + 6th, 2n + 7th columns and the n 2 + n - 4, n 2 + n - 3, n 2 + n - 2, and n 2 + n - 1 columns of the second matrix are given below:

[0109] α 2n+4 = [cos(θ 21 + θ 31 ) cos(θ 22 + θ 32 ) … cos(θ 2m + θ 3m )] T ;

[0110] α 2n+5 = [sin(θ 21 + θ 31 ) sin(θ 22 + θ 32 ) … sin(θ 2m + θ 3m )] T ;

[0111] α 2n+6 = [cos(θ 31 + θ 41 ) cos(θ 32 + θ 42 ) … cos(θ 3m + θ 4m )] T ;

[0112] α 2n+7 = [sin(θ 31 + θ 41 ) sin(θ 32 + θ 42 ) … sin(θ 3m + θ 4m )] T ;

[0113]

[0114]

[0115]

[0116]

[0117] In other words, the second matrix can satisfy:

[0118]

[0119] , where A represents the second matrix, and θ nm represents the target phase of the m-th measurement beam corresponding to the n-th chamber. In this case, the second matrix includes the DC component representing the signal of the measurement beam (i.e., the first column of the second matrix), the sine and cosine values of the target phases of the measurement beams corresponding to a single chamber, and the sine and cosine values of the sum of the target phases of the measurement beams corresponding to multiple chambers. When calculating the change amount of each chamber, the interference situation between the measurement beams reflected by different chambers of the fiber optic Fabry-Perot sensor 10 can be fully considered, thereby further improving the accuracy of demodulating each chamber.

[0120] In some examples, in step S430, the target matrix can satisfy Equation 7:

[0121] B = A -1 * I... Equation 7

[0122] where B represents the target matrix, A -1 represents the inverse matrix of the second matrix, and I represents the first matrix.

[0123] In some examples, if the preset quantity is m, the target matrix can be an m×1 order matrix.

[0124] In some examples, in step S440, the target phase difference of each chamber can satisfy Equation 8:

[0125]

[0126] where i represents the index of each chamber, and Δθ i represents the target phase difference of the i-th chamber, A -1 represents the inverse matrix of the second matrix, and I represents the first matrix. Thus, the target phase difference of each chamber can be conveniently calculated through the formula.

[0127] In other words, the target phase difference of each chamber can satisfy:

[0128] where B 2i+1 represents the element in the first column of the (2i + 1)-th row of the target matrix, and B 2i represents the element in the first column of the 2i-th row of the target matrix.

[0129] In the present disclosure, the target phase difference of each chamber represents the phase change caused by the change in the cavity length or refractive index of each chamber of the fiber Fabry-Perot sensor 10.

[0130] In some examples, in step S440, the target phase difference of each chamber can be corrected.

[0131] In some examples, the target phase difference of each chamber can be corrected based on the correction value and the target phase difference of each chamber at different times. In some examples, the correction value can be π. In this case, since the principal value range of the target phase difference obtained by using the arctangent algorithm is from -π / 2 to π / 2, when the target phase difference of each chamber exceeds this principal value range, a phase jump will occur. At this time, a more accurate target phase difference can be obtained by correcting the target phase difference of each chamber.

[0132] Figure 5 is a flowchart showing the correction of the target phase difference of each chamber involved in the examples of the present disclosure. Figure 6 is a schematic diagram showing the correction of the target phase difference of each chamber involved in the examples of the present disclosure. Among them, Figure 6 the multi-segment discontinuous curves within the solid-line box in represent the target phase difference of each chamber before correction, Figure 6 and the continuous curve that rises and then falls in represents the target phase difference of each chamber after correction.

[0133] In some examples, referring to Figure 5 , correcting the target phase difference of each chamber can include: calculating the difference between the target phase difference of each chamber at the current moment and the target phase difference at the next moment (step S4410); determining whether the difference between the target phase difference of each chamber at the current moment and the target phase difference at the next moment is greater than a first preset value (step S4420); and determining whether the difference between the target phase difference of each chamber at the current moment and the target phase difference at the next moment is less than a second preset value (step S4430). Thus, by determining the relationship between the difference between the target phase difference at the current moment and the target phase difference at the next moment and the first preset value and the second preset value respectively, the method for correcting the target phase difference of each chamber can be conveniently determined.

[0134] In some examples, in step S4410, the target phase difference of each chamber at the current moment can be subtracted by the target phase difference at the next moment to obtain the difference between the two.

[0135] In some examples, in step S4420, the first preset value can be any value selected from 0 to π. For example, the first preset value can be 1.

[0136] In some examples, in step S4420, if the difference between the target phase difference of each chamber at the current moment and the target phase difference at the next moment is greater than the first preset value, the correction value can be added to the target phase difference of each chamber later than the current moment.

[0137] In some examples, in step S4430, the first preset value can be selected from any value between -π and 0. For example, the second preset value can be -1.

[0138] In some examples, in step S4430, if the difference between the target phase difference of each chamber at the current moment and the target phase difference at the next moment is less than the second preset value, the correction value can be subtracted from the target phase difference of each chamber later than the current moment.

[0139] In some examples, in step S450, the change amount corresponding to each chamber can satisfy formula 9:

[0140] ΔS i =λ c *Δθ i / (2π)…Formula 9

[0141] Wherein, ΔS i represents the change amount corresponding to each chamber, λ c represents the average value of the central wavelengths of all preset numbers of measurement beams, and Δθ i represents the target phase difference of the i-th chamber. Thus, the change amount corresponding to each chamber can be conveniently calculated through the formula.

[0142] In some examples, in step S450, the change amount corresponding to each chamber can be calculated based on the corrected target phase difference of each chamber.

[0143] As described above, the demodulation method may further include: obtaining the measured quantity based on the change amount of each chamber (step S500).

[0144] In some examples, the target optical path of each chamber can be re-determined based on the change amount corresponding to each chamber and the target optical path of each chamber, and the change amount corresponding to each chamber can be recalculated based on the re-determined target optical path of each chamber according to the foregoing steps.

[0145] Figure 7 is a flowchart showing the re-determination of the target optical path of each chamber involved in the examples of the present disclosure.

[0146] In some examples, referring to Figure 7, re - determining the target optical path of each chamber may include: determining whether the absolute value of the change amount corresponding to each chamber is greater than a preset threshold (step S510); keeping the target optical path of each chamber unchanged (step S520); and making the target optical path of each chamber after re - determination equal to the sum of the target optical path of each chamber before re - determination and the change amount corresponding to each chamber (step S530). In this case, when the current change amount corresponding to each chamber is small, keeping the target optical path of each chamber unchanged can control the error within the desired range while reducing the computational amount. When the current change amount corresponding to each chamber is large, re - using the current change amount corresponding to each chamber to determine the target optical path of each chamber can still control the error within the desired range in the subsequent calculation process.

[0147] In some examples, in step S510, the preset threshold can be any value. In some examples, the preset threshold can be selected according to the error requirement or computational amount requirement of demodulation. For example, if it is desired to reduce the error of demodulation, a smaller preset threshold can be selected; if it is desired to reduce the computational amount of demodulation, a larger preset threshold can be selected. Preferably, the preset threshold can be any value selected from 50 nanometers to 1500 nanometers. For example, the preset threshold can be 50 nanometers, 100 nanometers, 200 nanometers, 500 nanometers, 1000 nanometers, or 1500 nanometers, etc.

[0148] In some examples, referring to Figure 7 , if the absolute value of the change amount corresponding to each chamber is not greater than the preset threshold, the target optical path of each chamber can be kept unchanged.

[0149] In some examples, in step S520, after obtaining the measured quantity based on the change amount of each current chamber, the target optical path of each chamber can be kept unchanged, and the measured quantity can be continuously measured according to the foregoing steps.

[0150] In some examples, referring to Figure 7 , if the absolute value of the change amount corresponding to each chamber is greater than the preset threshold, the target optical path of each chamber after re - determination can be made equal to the sum of the target optical path of each chamber before re - determination and the change amount corresponding to each chamber. That is to say, if the absolute value of the change amount corresponding to each chamber is greater than the preset threshold, it is necessary to increase or decrease the current target optical path of each chamber according to the change amount corresponding to each chamber to obtain the new target optical path of each chamber.

[0151] In some examples, in step S530, after obtaining the measured quantity based on the change amount of each current chamber, the target optical path of each chamber can be changed, and the measured quantity can be continuously measured according to the foregoing steps.

[0152] The present disclosure also provides a demodulation system for an optical fiber Fabry-Perot sensor 10 (hereinafter may be simply referred to as the demodulation system), which is a demodulation system for demodulating the optical fiber Fabry-Perot sensor 10 to obtain the measured quantity. The demodulation system can execute the demodulation method involved in the present disclosure.

[0153] The demodulation system for the optical fiber Fabry-Perot sensor 10 involved in the present disclosure can also be referred to as a system for demodulating the optical fiber Fabry-Perot sensor 10 and a demodulation system for obtaining the measured quantity based on the optical fiber Fabry-Perot sensor 10, etc. The demodulation system involved in the present disclosure can be applied to any application scenario that requires demodulating the optical fiber Fabry-Perot sensor 10 to obtain the measured quantity.

[0154] Hereinafter, with reference to the accompanying drawings, the demodulation system involved in the present disclosure will be described in detail.

[0155] Figure 8 It is a block diagram showing the modules of the demodulation system 1 involved in the examples of the present disclosure.

[0156] In some examples, referring to Figure 8 , the demodulation system 1 may include an optical fiber Fabry-Perot sensor 10. The demodulation system 1 can execute the demodulation method involved in the present disclosure to demodulate the optical fiber Fabry-Perot sensor 10.

[0157] In some examples, referring to Figure 8 , the demodulation system 1 may include a transmitting module 20.

[0158] In some examples, the transmitting module 20 can be used to emit a light beam. In some examples, the light beam can be a laser. In some examples, the light beam can be the aforementioned measurement light beam.

[0159] In some examples, the transmitting module 20 can emit white light. In some examples, the transmitting module 20 can emit light of other colors.

[0160] In some examples, the transmitting module 20 can be used to emit a light beam with a preset wavelength range. In some examples, the preset wavelength range can be a relatively large wavelength range. For example, the preset wavelength range can be from 1200 nanometers to 1600 nanometers. In some examples, the preset wavelength range can be a relatively small wavelength range. For example, the preset wavelength range can be from 1500 nanometers to 160 nanometers. In some examples, the preset wavelength range can be continuous. In some examples, the preset wavelength range can be non - continuous.

[0161] In some examples, the transmitting module 20 can be used to emit multiple light beams with a preset wavelength range. In some examples, the multiple light beams with a preset wavelength range can have different central wavelengths.

[0162] In some examples, the emission module 20 may be an ASE (Amplified Spontaneous Emission) broadband light source, an SLED (Super luminescent LED) broadband light source, a narrow linewidth laser light source, an SLD (Superluminescent diode) broadband light source, a bench-top laser light source, a modular laser light source, or the like.

[0163] In some examples, the emission module 20 may emit a light beam and incident on the fiber Fabry-Perot sensor 10. As described above, the fiber Fabry-Perot sensor 10 may reflect the incident light beam.

[0164] In some examples, referring to Figure 8 , the demodulation system 1 may further include a connection module 30. The connection module 30 may be used to guide the propagation directions of the light beam emitted by the emission module 20 and the light beam reflected by the fiber Fabry-Perot sensor 10.

[0165] In some examples, the connection module 30 may be connected to the emission module 20 and the fiber Fabry-Perot sensor 10. The light beam emitted by the emission module 20 may be incident on the fiber Fabry-Perot sensor 10 through the connection module 30, and the light beam reflected by the fiber Fabry-Perot sensor 10 may exit through the connection module 30.

[0166] Figure 9 is a schematic structural diagram of the connection module 30 involved in the examples of the present disclosure. Among them, Figure 9 also shows the connection relationship between the connection module 30 and the fiber Fabry-Perot sensor 10, the emission module 20, and the filter module 40 (described later).

[0167] In some examples, referring to Figure 9 , the connection module 30 may have three ports. The three ports may include a first port connected to the emission module 20, a second port connected to the fiber Fabry-Perot sensor 10, and a third port connected to the filter module 40. In some examples, the light beam input to the first port may be output from the second port, and the light beam input to the second port may be output from the third port. In this case, when the light beam emitted by the emission module 20 is input to the first port, it can be incident on the fiber Fabry-Perot sensor 10 from the second port. When the light beam reflected by the fiber Fabry-Perot sensor 10 is input to the second port, it can be output to the filter module 40 from the third port, thereby reducing the influence of the light beam reflected by the fiber Fabry-Perot sensor 10 on the emission module 20.

[0168] In some examples, the connection module 30 may be a fiber optic circulator or a 1×2 coupler, etc.

[0169] In some examples, referring to Figure 8, the demodulation system 1 may further include a filter module 40. The filter module 40 may receive the light beam reflected by the fiber optic Fabry-Perot sensor 10.

[0170] In some examples, referring to Figure 9 , the filter module 40 may be connected to the connection module 30. The filter module 40 may receive the light beam reflected by the fiber optic Fabry-Perot sensor 10 exiting from the connection module 30.

[0171] In some examples, the filter module 40 may include multiple output ports. The filter module 40 may output multiple light beams with different central wavelengths. In some examples, the filter module 40 may output a preset number of light beams with different central wavelengths. In some examples, the filter module 40 may output multiple light beams whose central wavelengths are within the wavelength range of the received light beam. In some examples, the filter module 40 may output multiple light beams whose central wavelengths are within the wavelength range of the received light beam and the central wavelengths are different from each other.

[0172] In some examples, the filter module 40 may be an optical filter. For example, the filter module 40 may be a wavelength division multiplexer, a fiber grating array, or an AWG (Arrayed Waveguide Grating), etc.

[0173] In some examples, the filter module 40 may include multiple channels. Each channel may have a different 3dB bandwidth. Thus, it is possible to output multiple light beams with different central wavelengths.

[0174] In some examples, referring to Figure 8 , the demodulation system 1 may further include a conversion module 50. The conversion module 50 may be connected to the filter module 40. The conversion module 50 may receive the multiple light beams output by the filter module 40 and convert them into electrical signals. Thus, it is possible to facilitate the demodulation of the information carried by the light beam. In some examples, the electrical signal may include an analog signal.

[0175] In some examples, the conversion module 50 may include a sensing unit. The sensing unit may be connected to the filter module x0. In some examples, the sensing unit may include a multi-channel photodetector. The multiple output ports of the filter module 40 may be respectively connected to the channels of the multi-channel photodetector through optical fibers. In this case, it is possible to use the sensing unit to receive the multiple light beams output by the filter module 40 and convert the multiple light beams into analog signals, thereby improving the convenience of subsequent demodulation.

[0176] In some examples, the conversion module 50 may further convert the analog signal into a digital signal. The electrical signal may include a digital signal.

[0177] In some examples, referring toFigure 8 In addition, the demodulation system 1 may further include a processing module 60. The processing module 60 may be connected to the conversion module 50.

[0178] In some examples, the processing module 60 may include circuits such as signal conditioning, analog-to-digital conversion, data acquisition, and arithmetic processing. Thus, it is possible to facilitate the analysis and processing of analog signals.

[0179] In some examples, the processing module 60 may perform the foregoing steps of calculating the target optical path of each chamber, calculating the target phase of each beam of light corresponding to each chamber, determining the target matrix, calculating the change amount of the relative target optical path corresponding to each chamber, calculating the target phase difference of each chamber, correcting the target phase difference of each chamber, and calculating the measured quantity based on the multiple beams of light output by the filter module 40. In some examples, the conversion module 50 may first convert the multiple beams of light output by the filter module 40 into electrical signals, and then the processing module 60 may perform the foregoing steps based on the electrical signals.

[0180] In some examples, the processing module 60 may obtain the measured quantity based on the electrical signals, the central wavelengths of the multiple beams of light, and the initial parameters of the fiber Fabry-Perot sensor 10. The initial parameters of the fiber Fabry-Perot sensor 10 may include the initial optical paths of the respective chambers of the fiber Fabry-Perot sensor 10.

[0181] In the present disclosure, each chamber has a corresponding target phase with respect to the measurement beams of different central wavelengths. The number of measurement beams satisfies a preset relationship with the total number of each chamber. The light intensity of the measurement beams reflected by the fiber Fabry-Perot sensor 10 includes the changes in the target optical paths of each chamber under the action of the measured quantity. Through the target matrix determined based on the light intensity of each measurement beam and the target phase of each measurement beam corresponding to each chamber, the change amount of the relative target optical path corresponding to each chamber can be calculated. Thus, each chamber of the fiber Fabry-Perot sensor 10 can be demodulated. In addition, the number of measurement beams satisfies a preset relationship with the total number of each chamber, which can make the number of measurement beams adapt to the change in the number of chambers. Therefore, when the number of chambers increases, more information of the measurement beams can be used to demodulate each chamber, and thus the accuracy of demodulating each chamber can be improved.

[0182] In addition, in the present disclosure, the demodulation system 1 may include a fiber Fabry-Perot sensor 10, a transmitting module 20, a connecting module 30, a filter module 40, and a processing module 60. Thus, each chamber of the fiber Fabry-Perot sensor 10 can be demodulated.

[0183] Although the present disclosure has been specifically described above in connection with the accompanying drawings and embodiments, it is to be understood that the above description does not limit the present disclosure in any way. Those skilled in the art can make modifications and variations to the present disclosure as needed without departing from the essence and scope of the present disclosure, and these modifications and variations all fall within the scope of the present disclosure.

Claims

1. A demodulation method for a fiber optic Fabry-Perot sensor, the fiber optic Fabry-Perot sensor being used to measure a measurand and including a fiber optic Fabry-Perot single cavity sensor and a fiber optic Fabry-Perot multi-cavity sensor, the fiber optic Fabry-Perot single cavity sensor including a single chamber, and the fiber optic Fabry-Perot multi-cavity sensor including a plurality of chambers connected in parallel and in series, characterized in that, The demodulation method is used to demodulate each chamber of a plurality of serially-connected fiber Fabry single-chamber sensors or each chamber of a plurality of chambers of a fiber Fabry multi-chamber sensor, and includes: Obtaining the initial optical path of each chamber, where the initial optical path of each chamber represents the optical path required for a light beam to experience a round trip in each chamber before using the fiber Fabry sensor; Obtaining a preset number of measurement light beams reflected by the fiber Fabry sensor, where the preset number satisfies a preset relationship with the total number of each chamber, and the central wavelengths of the preset number of measurement light beams are different from each other; Calculating the target phase of each measurement light beam corresponding to each chamber based on the target optical path of each chamber and the central wavelength of the preset number of measurement light beams, and the initial value of the target optical path of each chamber is the initial optical path of each chamber; Determining a target matrix based on the light intensity of each measurement light beam and the target phase of each measurement light beam corresponding to each chamber, calculating the change amount of each chamber corresponding to the target optical path based on the target matrix, and at least one of the dimensions of the rows and columns of the target matrix is the preset number; and Obtaining the measured quantity based on the change amount corresponding to each chamber.

2. The demodulation method of the fiber optic Fabry-Perot sensor according to claim 1, characterized in that, The target phase of each measurement light beam corresponding to each chamber satisfies the formula: θ ij = 2π * S i / λ j , Among them, i represents the index of each chamber, j represents the index of the preset number of measurement beams, and S i represents the target optical path of the i-th chamber, and λ j represents the central wavelength of the j-th measurement beam, and θ ij represents the target phase of the j-th measurement beam corresponding to the i-th chamber.

3. The demodulation method of the fiber optic Fabry-Perot sensor according to claim 1 or 2, characterized in that, The preset relationship satisfies the formula: m = n 2 + n + 1, Where n represents the total number of each chamber, and m represents the preset number.

4. The demodulation method of the fiber optic Fabry-Perot sensor according to claim 3, characterized in that, Calculating the change amount corresponding to each chamber includes: Constructing a first matrix, where the elements of the first matrix are the light intensities of the preset number of measurement light beams; Constructing a second matrix, where the order of the second matrix is the preset number and the elements of the second matrix are related to the target phase of each measurement light beam corresponding to each chamber; Multiplying the inverse matrix of the second matrix by the first matrix to determine the target matrix; Obtaining the target phase difference of each chamber based on the target matrix; and Calculating the change amount corresponding to each chamber based on the target phase difference of each chamber.

5. The demodulation method of the fiber optic Fabry-Perot sensor according to claim 4, characterized in that, The second matrix satisfies the formula: where A represents the second matrix, and θ nm represents the target phase of the m-th measurement beam corresponding to the n-th chamber.

6. The demodulation method of the fiber optic Fabry-Perot sensor according to claim 5, characterized in that, The target phase difference of each chamber satisfies the formula: where i represents the index of each chamber, Δθ i represents the target phase difference of the i-th chamber, A -1 represents the inverse matrix of the second matrix, and I represents the first matrix.

7. The demodulation method of the fiber optic Fabry-Perot sensor according to claim 6, characterized in that, Correcting the target phase difference of each chamber based on the correction value and the target phase difference of each chamber at different times, where the correction value is π, and the correction includes: If the difference between the target phase difference of each chamber at the current moment and the target phase difference at the next moment is greater than a first preset value, adding the correction value to the target phase difference of each chamber later than the current moment; and If the difference between the target phase difference of each chamber at the current moment and the target phase difference at the next moment is less than a second preset value, subtracting the correction value from the target phase difference of each chamber later than the current moment.

8. The demodulation method of the fiber optic Fabry-Perot sensor according to claim 1, characterized in that Re-determining the target optical path of each chamber based on the change amount corresponding to each chamber and the target optical path of each chamber, and re-determining the target optical path of each chamber includes: If the absolute value of the change amount corresponding to each chamber is less than a preset threshold, keeping the target optical path of each chamber unchanged; and If the absolute value of the change amount corresponding to each chamber is greater than the preset threshold, making the re-determined target optical path of each chamber equal to the sum of the target optical path of each chamber before re-determination and the change amount corresponding to each chamber.

9. The demodulation method of the fiber optic Fabry-Perot sensor according to claim 1, characterized in that Obtaining the initial optical path of each chamber includes: Obtaining the white-light interference spectrum of the fiber Fabry-Perot sensor based on the beam; Performing Fourier transform on the white-light interference spectrum to obtain the spectrum corresponding to the white-light interference spectrum; Filtering the spectrum to obtain a plurality of sub-spectra corresponding to each chamber; Filtering the white-light interference spectrum according to the plurality of sub-spectra to obtain a plurality of sub-spectra corresponding to each chamber; and Performing peak-to-peak operation on the plurality of sub-spectra respectively to obtain the initial optical path of each chamber.

10. A demodulation system for a fiber optic Fabry-Perot sensor, characterized in that, Including: The fiber Fabry-Perot sensor, a transmitting module, a connecting module, a filtering module and a processing module, wherein the transmitting module emits a beam and the beam is incident on the fiber Fabry-Perot sensor through the connecting module, the fiber Fabry-Perot sensor reflects the beam and inputs the beam into the filtering module through the connecting module, the filtering module outputs a plurality of beams with different central wavelengths, and the processing module executes the demodulation method of the fiber Fabry-Perot sensor according to any one of claims 1 to 9 based on the plurality of beams output by the filtering module.

Images