A multi-parameter sensor based on fiber grating, a measuring method and system

Abstract

The application provides a kind of multi-parameter sensor based on fiber grating, measurement method and system, the sensor includes: optical fiber, including optical fiber core and optical fiber cladding, wherein, optical fiber cladding is wrapped optical fiber core;Grating is uniformly distributed in optical fiber core;Polyimide metal hybrid coating is coated and wrapped optical fiber cladding;Insulating coating is coated and wrapped polyimide metal hybrid coating.By setting polyimide metal hybrid coating with conductive ability, the adjustment of optical fiber temperature is realized, and the wavelength shift of grating will be caused by temperature change, then the temperature field distribution is obtained according to the wavelength shift of grating, so as to measure the liquid level of liquid, and the flow is measured according to temperature difference, the liquid level height and flow two variables are measured in the same equipment.

Description

Technical Field

[0001] This invention relates to the field of fiber optic sensing, and more particularly to a multi-parameter sensor, measurement method and system based on fiber Bragg gratings. Background Technology

[0002] In the industrial sector, gaseous and liquid media are important controlled objects. For example, the fuel level and distribution in aircraft fuel tanks are crucial parameters for adjusting the aircraft's center of gravity and balance, as well as calculating fuel levels and planning flight routes and distances. Monitoring parameters such as the flow rate of oil and gas pipelines is key to achieving unmanned or minimally manned intelligent management of pipeline networks and stations. Since most gaseous and liquid media are fuels or chemicals that are flammable and explosive, they require strict monitoring.

[0003] Currently, in order to measure the liquid level and flow rate of a gas-liquid medium, it is necessary to measure the two variables separately. In other words, two different devices are required to obtain the two parameters of liquid level and flow rate of the gas-liquid medium.

[0004] Therefore, existing technologies have the problem that they cannot measure both the liquid level and flow rate using the same equipment when measuring the liquid level and flow rate of gas-liquid media. Summary of the Invention

[0005] In view of this, it is necessary to provide a multi-parameter sensor based on fiber Bragg grating and its measurement method, which can simultaneously measure two variables, liquid level and flow rate, of a gas-liquid medium using the same device.

[0006] To achieve the above objectives, the present invention provides a multi-parameter sensor based on a fiber Bragg grating, comprising:

[0007] Optical fiber includes the fiber core and the fiber cladding, wherein the fiber cladding wraps around the fiber core.

[0008] The grating is uniformly distributed in the fiber core;

[0009] A polyimide-metal hybrid coating is used to coat the fiber cladding.

[0010] Insulating coating, coated with a polyimide-metal hybrid coating.

[0011] To achieve the above objectives, the present invention also provides a multi-parameter measurement method based on fiber Bragg gratings, comprising:

[0012] The insulating coating at both ends of the optical fiber is stripped to expose the polyimide-metal hybrid coating, and a power source is applied to the exposed polyimide-metal hybrid coating.

[0013] A fiber Bragg grating-based multi-parameter sensor is placed in the liquid to be measured to obtain the wavelength shift.

[0014] The liquid level and flow rate of the liquid to be measured are determined based on the wavelength offset.

[0015] Furthermore, a multi-parameter sensor based on a fiber Bragg grating is placed in the liquid to be measured to obtain the wavelength shift, including:

[0016] A multi-parameter sensor based on a fiber Bragg grating is placed in the liquid to be measured, such that the axial direction of the fiber is perpendicular to the liquid surface direction.

[0017] The initial wavelength is obtained by a multi-parameter sensor based on a fiber Bragg grating, and the current of the power supply is adjusted to obtain the corresponding adjusted wavelength.

[0018] The wavelength offset is obtained by subtracting the initial wavelength and the adjusted wavelength.

[0019] Furthermore, based on the wavelength shift, the liquid level of the liquid to be measured is determined, including:

[0020] The temperature distribution information of the optical fiber is determined based on the wavelength offset.

[0021] Based on the temperature distribution information, determine the location of the temperature abrupt change in the grating;

[0022] The liquid level of the liquid to be tested is determined based on the location of the temperature change.

[0023] Furthermore, based on the temperature distribution information, the locations of temperature abrupt changes in the grating are determined, including:

[0024] The temperature distribution information is processed into a continuous form by using an interpolation algorithm, thus obtaining continuous temperature distribution information.

[0025] Based on continuous temperature distribution information, the locations of temperature abrupt changes in the grating are determined.

[0026] Furthermore, based on the wavelength shift, the flow rate of the liquid to be measured is determined, including:

[0027] The temperature change of the optical fiber is determined based on the wavelength offset.

[0028] Determine the heat change value of the optical fiber based on the temperature change value;

[0029] The flow rate of the liquid to be measured is determined based on the wavelength shift and its corresponding heat change.

[0030] Furthermore, the gratings are arranged in an array using a wavelength division multiplexing method.

[0031] Furthermore, the polyimide-metal hybrid coating comprises a polyimide polymer, cobalt chloride, and lithium chloride.

[0032] Furthermore, the insulating coating includes acrylates.

[0033] To achieve the above objectives, the present invention also provides a multi-parameter measurement system based on fiber Bragg gratings, including a multi-parameter sensor based on fiber Bragg gratings as described above, or a multi-parameter measurement method based on fiber Bragg gratings as described above.

[0034] The beneficial effects of adopting the above technical solution are as follows: This invention provides a multi-parameter sensor, measurement method, and system based on a fiber Bragg grating. The sensor includes: an optical fiber, comprising an optical fiber core and an optical fiber cladding, wherein the optical fiber cladding wraps around the optical fiber core; a grating, uniformly distributed within the optical fiber core; a polyimide-metal hybrid coating, coating the optical fiber cladding; and an insulating coating, coating the polyimide-metal hybrid coating. By setting a conductive polyimide-metal hybrid coating, the temperature of the optical fiber can be adjusted. Temperature changes cause a wavelength shift in the grating. Then, the temperature field distribution is obtained based on the wavelength shift of the grating, thereby measuring the liquid level and the flow rate based on the temperature difference. This allows for the measurement of both liquid level and flow rate using the same device. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of an embodiment of the multi-parameter sensor based on fiber Bragg grating provided by the present invention;

[0036] Figure 2 A flowchart illustrating an embodiment of the multi-parameter measurement method based on fiber Bragg grating provided by the present invention;

[0037] Figure 3 This is a schematic flowchart of an embodiment of the present invention for obtaining wavelength offset;

[0038] Figure 4 A schematic flowchart illustrating an embodiment of the present invention for determining the liquid level of a liquid to be tested;

[0039] Figure 5 This is a schematic flowchart illustrating an embodiment of the present invention for determining the flow rate of a liquid to be measured. Detailed Implementation

[0040] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0041] Before describing the embodiments, we will first explain optical fibers, optical fiber sensing technology, and polyimide:

[0042] Optical fiber has a wide operating bandwidth and a large dynamic range, making it suitable for telemetry and remote control. It is an excellent low-loss transmission line. Under certain conditions, optical fiber is particularly easy to accept the load of the measured quantity or field, making it an excellent sensing element. Optical fiber itself is non-electric, small in size, light in weight, flexible, and has good resistance to electromagnetic interference and radiation. It is particularly suitable for use in harsh environments such as flammable, explosive, space-constrained, and strong electromagnetic interference environments.

[0043] Fiber optic sensing encompasses both sensing and transmission of external signals (the measurand). Fiber optic sensing technology offers advantages such as resistance to electromagnetic interference, radiation resistance, intrinsic safety, and long-distance transmission. Sensing (or sensitivity) refers to the process by which external signals, according to their changing patterns, alter the physical characteristics of the light waves propagating in the fiber optic cable, such as intensity (power), wavelength, frequency, phase, and polarization state. Measuring these changes in optical parameters is equivalent to "sensing" the changes in the external signal. This "sensing" is essentially the real-time modulation of the light waves propagating in the fiber optic cable by the external signal. Transmission refers to the fiber optic cable transmitting the light waves modulated by the external signal to a photodetector for detection. The external signal is then extracted from the light wave and processed as needed—that is, demodulated. Therefore, fiber optic sensing technology includes both modulation and demodulation techniques: modulation techniques (or loading techniques) on how the external signal (the measurand) modulates the optical wave parameters in the fiber optic cable, and demodulation techniques (or detection techniques) on how to extract the external signal (the measurand) from the modulated light wave.

[0044] Polyimide is one of the highest-temperature-range polymer materials commercially available to date, exhibiting high thermal stability, strength, and modulus. Furthermore, polyimide-metal hybrid materials possess certain electrical conductivity. Among numerous metal elements, Ag, Pd, Co, Cu, Li, and Sn have been studied in greater depth. Doping polyimide with these elements significantly reduces both volume resistivity and surface resistivity, converting electrical energy into heat when electricity is applied. Currently, its application in optical fiber coatings is limited, indicating that polyimide-metal hybrid coating materials hold immense potential in the field of optical fiber sensing.

[0045] Currently, measuring the liquid level and flow rate of gaseous and liquid media requires two types of measuring instruments: a liquid level measuring device and a flow rate measuring device. Therefore, existing technologies have the problem that they cannot measure both liquid level and flow rate using the same equipment.

[0046] To address the aforementioned problems, this invention provides a multi-parameter sensor, measurement method, and system based on fiber Bragg gratings, which will be described in detail below.

[0047] like Figure 1 As shown, Figure 1This is a schematic diagram of an embodiment of a fiber Bragg grating-based multi-parameter sensor provided by the present invention. The fiber Bragg grating-based multi-parameter sensor 10 includes:

[0048] Optical fiber 11, wherein optical fiber 11 includes optical fiber core 111 and optical fiber cladding 112, and optical fiber cladding 112 wraps around optical fiber core 111;

[0049] The grating 12 is uniformly distributed in the fiber core 111;

[0050] Polyimide metal hybrid coating 13 is used to coat the optical fiber cladding 112;

[0051] Insulating coating 14, coated with polyimide-metal hybrid coating 13.

[0052] In this embodiment, by layering the optical fiber 11, grating 12, polyimide-metal hybrid coating 13, and insulating coating 14 from the inside out, the heatable polyimide-metal hybrid coating 13 surrounds the optical fiber 11 and grating 12, and then the insulating coating 14 surrounds the polyimide-metal hybrid coating 13. This not only allows the location of temperature abrupt changes in the optical fiber 11 to be measured through the grating 12, thereby determining the liquid level height based on the location of temperature abrupt changes in the optical fiber 11; but also, based on the polyimide-metal hybrid coating 13, it is possible to change the temperature around the optical fiber 11 and grating 12, thereby obtaining multiple sets of wavelengths of the grating 12 based on different temperatures. Then, the temperature difference is determined based on the multiple sets of wavelengths, the heat difference is determined based on the temperature difference, and the flow rate is determined based on the temperature difference and the heat difference. By applying a polyimide-metal hybrid coating 13 that adheres to the grating 12, the temperature around the grating 12 can be adjusted according to actual needs, thereby acquiring multiple wavelengths of the grating 12. Based on these wavelengths, both the liquid level and flow rate can be determined, enabling a single device (fiber optic multi-parameter sensor 10) to measure both parameters. Furthermore, the fiber optic multi-parameter sensor 10 is not only small, lightweight, and simple in structure, but also, due to the electromagnetic interference and corrosion resistance properties of fiber optic gratings, is suitable for various applications.

[0053] In a preferred embodiment, the optical fiber 11 is a single-mode sensing optical fiber, the polyimide-metal hybrid coating 13 includes cobalt chloride and lithium chloride, and the insulating coating 14 is acrylate.

[0054] In one specific embodiment, the preset ratio of the mixture in the polyimide metal hybrid coating 13 is: BTDA:ODA:CoCl2:LiCl = 4:4:1:0.5, where the above is the molar ratio of each component. By setting the ratio of the mixture in the polyimide metal hybrid coating 13, the conductivity of the polyimide metal hybrid coating 13 can be improved, and it can withstand high temperatures.

[0055] In other embodiments, the composition ratio of the mixture in the polyimide-metal hybrid coating 13 can be adjusted as needed.

[0056] As a preferred embodiment, in order to reasonably distribute the gratings, wavelength division multiplexing is used to arrange the gratings in an array to achieve quasi-distributed distribution.

[0057] In one specific embodiment, the wavelength spacing between adjacent gratings is set to 3 nm, the grating pitch is 3 mm, the grating length is 5 mm, and the reflectivity is 75%.

[0058] Generally, when the temperature changes by 1°C, the center wavelength of the grating shifts by about 10 pm. Therefore, a wavelength interval of 3 nm can accommodate temperature changes of up to 300°C. The grating pitch and grating length determine the density of the grating. Based on the above settings, theoretically, a liquid level change of 8 mm can be measured, meaning that the liquid level measurement accuracy can reach 8 mm. Furthermore, the high reflectivity of the grating means that the signal is easier to read and the waveform will look better.

[0059] In other embodiments, the parameters of the grating wavelength spacing, grating pitch, grating area length, and reflectivity can be adaptively adjusted as needed.

[0060] To address the aforementioned problems, this invention also provides a multi-parameter measurement method based on fiber Bragg gratings, such as... Figure 2 As shown, Figure 2 A flowchart illustrating an embodiment of the multi-parameter measurement method based on fiber Bragg grating provided by the present invention includes:

[0061] Step S101: Strip the insulating coating at both ends of the optical fiber to expose the polyimide-metal hybrid coating, and apply a power source to the exposed polyimide-metal hybrid coating.

[0062] Step S102: Place the fiber optic multi-parameter sensor in the liquid to be tested and obtain the wavelength shift.

[0063] Step S103: Determine the liquid level and flow rate of the liquid to be measured based on the wavelength offset.

[0064] In this embodiment, firstly, in order to allow the polyimide-metal hybrid coating to be smoothly connected to the power source, the insulation layer at both ends of the optical fiber is stripped to expose the polyimide-metal hybrid coating, and then electrodes are added. Then, the fiber Bragg grating-based multi-parameter sensor with the added power source is placed in the liquid to be tested. By adjusting the current of the power source, the wavelength offset of multiple sets of optical signals after passing through the fiber Bragg grating-based multi-parameter sensor is obtained. Finally, based on the multiple sets of wavelength offsets, and based on the relationship between liquid level and wavelength, and the relationship between flow rate and wavelength, the liquid level and flow rate of the liquid to be tested are determined.

[0065] In this embodiment, the conductivity of the polyimide-metal hybrid coating is fully utilized. When energized, electrical energy is converted into heat energy, providing heat to the fiber Bragg grating and regulating its temperature. Furthermore, the non-conductive insulating coating protects the polyimide-metal hybrid coating from corrosion, ensuring the normal operation of the fiber Bragg grating-based multi-parameter sensor in gas-liquid media. During measurement, an electric current is applied to the polyimide-metal hybrid coating, providing a changing ambient temperature for the fiber Bragg grating. By observing the wavelength change of the grating, the temperature field along the fiber axis can be measured. This allows for the measurement of not only the liquid level but also the flow rate of the liquid being tested.

[0066] In one specific embodiment, in order to ensure the insulation effect of the insulating coating and avoid short circuits, in step S101, after applying power to the exposed polyimide-metal hybrid coating, an insulating coating can be applied again to the excess exposed polyimide-metal hybrid coating to ensure the safety of the polyimide-metal hybrid coating during the power-on process.

[0067] In a preferred embodiment, in step S102, in order to obtain the wavelength offset based on a fiber Bragg grating-based multi-parameter sensor, such as... Figure 3 As shown, Figure 3 A schematic flowchart of an embodiment of the present invention for obtaining wavelength offset includes:

[0068] Step S121: Place the fiber optic multi-parameter sensor in the liquid to be measured, such that the axial direction of the fiber is perpendicular to the liquid surface direction.

[0069] Step S122: Based on the initial wavelength obtained from the multi-parameter sensor based on fiber Bragg grating, adjust the current of the power supply to obtain the corresponding adjusted wavelength.

[0070] Step S123: Obtain the wavelength offset by subtracting the initial wavelength and the adjusted wavelength.

[0071] In this embodiment, by placing a fiber optic multi-parameter sensor in the liquid to be measured and adjusting the current of the power supply as needed, multiple sets of initial wavelength information and multiple sets of adjusted wavelength information are obtained. Finally, according to the measurement requirements, the initial wavelength information and its corresponding adjusted wavelength information are subtracted to obtain multiple sets of wavelength differences, i.e., multiple sets of wavelength offsets.

[0072] In a preferred embodiment, in step S103, in order to determine the liquid level of the liquid to be measured based on the wavelength offset, such as... Figure 4 As shown, Figure 4 A flowchart illustrating an embodiment of the present invention for determining the liquid level of a liquid to be measured includes:

[0073] Step S131: Determine the temperature distribution information of the optical fiber based on the wavelength offset.

[0074] Step S132: Determine the location of temperature abrupt change in the grating based on the temperature distribution information.

[0075] Step S133: Determine the liquid level of the liquid to be tested based on the location of the temperature change.

[0076] In this embodiment, firstly, the temperature corresponding to each grating is determined based on the wavelength shift of the optical signal after passing through the grating, thus obtaining the temperature distribution of the grating and determining the temperature distribution information of the optical fiber. Then, the position of the corresponding grating is determined based on the location of the temperature abrupt change in the temperature distribution information. Finally, the liquid level of the liquid to be measured is determined based on the position of the grating where the temperature abrupt change occurs. Because the thermal conductivity of liquids and gases differs significantly, there will be a temperature abrupt change at the gas-liquid interface. By effectively utilizing the high temperature sensitivity of the optical fiber, the wavelength of the grating will shift according to the temperature, thereby enabling the measurement of the liquid level based on the fiber optic grating.

[0077] In one specific embodiment, in step S131, in order to determine the temperature distribution information of the optical fiber based on the wavelength offset, the temperature change value is determined using a temperature change formula. The temperature change formula is:

[0078]

[0079] Where ΔΤ is the temperature change, Δλ is the wavelength shift of the center wavelength, and n eff α is the effective refractive index of the optical fiber, α is the coefficient of thermal expansion, and Λ is the grating period.

[0080] By using the temperature change formula, the obtained wavelength offset is converted into a temperature change parameter, which allows for a more intuitive understanding of the location of temperature abrupt changes in the grating and improves the accuracy of liquid level measurement.

[0081] In one specific embodiment, in step S132, to improve the measurement resolution of the liquid level height, the spacing of the gratings can be set according to the required measurement accuracy. For example, the gratings can be set according to a fixed scale to form gratings arranged with spacing according to a certain scale order, thereby enabling the liquid level height to be determined by two gratings that change abruptly with temperature. Furthermore, the number of gratings can be increased to improve the grating density.

[0082] In another specific embodiment, in step S132, in order to ensure the accuracy of liquid level measurement based on a limited number of gratings, firstly, the temperature distribution information is processed into continuous temperature distribution information by interpolation algorithm. That is, based on the obtained scattered temperature data, the scattered temperature data is made continuous by interpolation algorithm to obtain continuously distributed temperature data. Then, based on the continuously distributed temperature data distribution information, the temperature change value is determined, and the temperature change position of the grating is determined accordingly based on the temperature change value, that is, the liquid level of the liquid to be measured is determined.

[0083] In a preferred embodiment, in step S103, in order to determine the flow rate of the liquid to be measured based on the wavelength offset, such as... Figure 5 As shown, Figure 5 A flowchart illustrating an embodiment of the present invention for determining the flow rate of a liquid to be measured includes:

[0084] Step S141: Determine the temperature change value of the optical fiber based on the wavelength offset.

[0085] Step S142: Determine the heat change value of the optical fiber based on the temperature change value.

[0086] Step S143: Determine the flow rate of the liquid to be measured based on the wavelength offset and its corresponding heat change value.

[0087] In one specific embodiment, in step S141, in order to obtain the temperature change value of the optical fiber based on the wavelength offset, the temperature change value is determined using a temperature change formula. The temperature change formula is:

[0088]

[0089] Where ΔΤ is the temperature change, Δλ is the center wavelength shift, and n eff α is the effective refractive index of the optical fiber, α is the coefficient of thermal expansion, and Λ is the grating period.

[0090] Furthermore, in step S142, after determining the temperature change value, it is also necessary to determine the heat change value according to the heat change formula. The heat change formula is:

[0091] ΔQ=cmΔT

[0092] Where ΔQ is the change in heat, i.e. the heat carried away by the fluid, C is the specific heat capacity, and m is the mass.

[0093] Furthermore, in step S143, after determining the temperature change and heat change values, it is also necessary to determine the flow rate of the liquid to be measured according to the flow rate formula. The flow rate formula is:

[0094]

[0095] Where ν is the flow rate of the liquid being measured, i.e., the velocity of the fluid, and A and B are fluid-related constants that can be obtained through calibration.

[0096] In this embodiment, the flow rate of the liquid to be measured is obtained by iterative calculation using multiple formulas. Not only is no new measuring instrument added, but the fiber optic grating is safe and reliable and can change its wavelength according to temperature changes, which effectively ensures the measurement accuracy of the flow rate of the liquid to be measured.

[0097] The above method involves several steps. First, the initial wavelength corresponding to the liquid level is obtained from a multi-parameter sensor based on a fiber Bragg grating. Then, the temperature of the fiber Bragg grating is adjusted using a temperature-adjustable polyimide-metal hybrid coating to obtain the corresponding adjusted wavelength, and the wavelength shift is obtained by subtraction. Next, the wavelength shift is converted into a temperature change, which is then converted into a heat change. Finally, the flow rate of the liquid is obtained based on the temperature and heat changes. This method not only allows for the determination of the temperature abrupt change position of the fiber Bragg grating to determine the liquid level but also enables the measurement of both the liquid level and flow rate using the same equipment.

[0098] To achieve the above objectives, the present invention also provides a multi-parameter measurement system based on fiber Bragg gratings, including a multi-parameter sensor based on fiber Bragg gratings as described above, or a multi-parameter measurement method based on fiber Bragg gratings as described above.

[0099] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-parameter measurement method based on fiber Bragg gratings, characterized in that, include: The insulating coating at both ends of the optical fiber is stripped to expose the polyimide-metal hybrid coating, and a power source is applied to the exposed polyimide-metal hybrid coating. The fiber optic multi-parameter sensor is placed in the liquid to be measured to obtain the wavelength shift. The liquid level and flow rate of the liquid to be tested are determined based on the wavelength offset. The fiber Bragg grating-based multi-parameter sensor includes: An optical fiber includes an optical fiber core and an optical fiber cladding, wherein the optical fiber cladding encloses the optical fiber core; The grating is uniformly distributed in the fiber core; A polyimide-metal hybrid coating is applied to the cladding of the optical fiber. An insulating coating is applied to encapsulate the polyimide-metal hybrid coating. Determining the liquid level of the liquid to be measured based on the wavelength offset includes: The temperature distribution information of the optical fiber is determined based on the wavelength offset. Based on the temperature distribution information, determine the location of the temperature abrupt change in the grating; The liquid level of the liquid to be tested is determined based on the location of the temperature change. Determining the flow rate of the liquid to be measured based on the wavelength offset includes: The temperature change value of the optical fiber is determined based on the wavelength offset. Based on the temperature change value, determine the heat change value of the optical fiber; The flow rate of the liquid to be tested is determined based on the wavelength offset and the corresponding heat change value. Determining the location of a temperature abrupt change in the grating based on the temperature distribution information includes: The temperature distribution information is processed into continuous information by interpolation algorithm to obtain continuous temperature distribution information; Based on the continuous temperature distribution information, the location of the temperature abrupt change in the grating is determined; The preset ratio of the mixture in the polyimide metal hybrid coating is: BTDA:ODA:CoCl2:LiCl = 4:4:1:0.

5.

2. The multi-parameter measurement method based on fiber Bragg grating according to claim 1, characterized in that, The step of placing the fiber Bragg grating-based multi-parameter sensor in the liquid to be measured and obtaining the wavelength shift includes: The fiber Bragg grating-based multi-parameter sensor is placed in the liquid to be tested, such that the axial direction of the optical fiber is perpendicular to the liquid surface direction of the liquid to be tested. The initial wavelength is obtained based on the fiber Bragg grating-based multi-parameter sensor, and the current of the power supply is adjusted to obtain the corresponding adjusted wavelength. The wavelength offset is obtained by subtracting the initial wavelength and the adjusted wavelength.

3. The multi-parameter measurement method based on fiber Bragg grating according to claim 1, characterized in that, The grating is arranged in an array using a wavelength division multiplexing method.

4. The multi-parameter measurement method based on fiber Bragg grating according to claim 1, characterized in that, The polyimide-metal hybrid coating comprises a polyimide polymer, cobalt chloride, and lithium chloride.

5. The multi-parameter measurement method based on fiber Bragg grating according to claim 1, characterized in that, The insulating coating comprises acrylate.

6. A multi-parameter measurement system based on fiber Bragg gratings, characterized in that, This includes the multi-parameter measurement method based on fiber Bragg gratings as described in any one of claims 1-5.

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