Optical fiber sensor and magnetic field strength measuring device

Abstract

The present application belongs to the field of optical fiber sensing and provides an optical fiber sensor and a magnetic field strength measuring device, the optical fiber sensor including an optical fiber and a magnetic member, at least one optical fiber is provided, the optical fiber is extended along a predetermined direction and has a predetermined position along the extending length of the optical fiber, a Bragg grating is formed at the predetermined position, the magnetic member is connected to the predetermined position of the optical fiber, the magnetic member can generate a positional displacement by a magnetic force so that the Bragg grating at the predetermined position generates a bending deformation perpendicular to the predetermined direction, and the magnetic field strength measuring device includes the optical fiber sensor. The present application aims to solve the technical problem in the prior art that current-carrying conductors are susceptible to electromagnetic interference and radio frequency interference, resulting in inaccurate measurement of magnetic field strength.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to a Chinese patent application filed with the China Patent Office on December 21, 2022, bearing application number 202211651105.4 and titled "Optical fiber sensor and magnetic field intensity measuring device," the entire contents of which are incorporated herein by reference.

[0002] The present application belongs to the field of optical fiber sensing technology, and in particular to an optical fiber sensor and a magnetic field intensity measuring device. [Background technology]

[0003] Magnetic field sensors are an important component of the sensor field, and measuring magnetic field strength has already been widely applied in fields such as aerospace, information storage and environmental monitoring.

[0004] Conventional methods for measuring and quantifying magnetic field strength are mostly based on Ampere-force theory, which refers to the force acting on a current-carrying conductor in a magnetic field, and conventional magnetic field sensors for measuring and quantifying magnetic field strength employ a current-carrying conductor as an inductive element.

[0005] However, conventional magnetic field sensors employing current-carrying conductors are susceptible to electromagnetic interference (EMI) or radio frequency interference (RFI) during measurement, which affects the accuracy of the measurement. Summary of the Invention [Problem to be solved by the invention]

[0006] The purpose of the present application is to provide an optical fiber sensor and a magnetic field strength measuring device to solve the technical problem in the prior art that current-carrying conductors are susceptible to electromagnetic interference and radio frequency interference, which leads to inaccurate measurement of magnetic field strength. [Means for solving the problem]

[0007] A first object of the present application is to provide an optical fiber sensor including an optical fiber and a magnetic member, At least one optical fiber is provided, the optical fiber extends along a predetermined direction, has a predetermined position along the extension length of the optical fiber, and a Bragg grating is formed at the predetermined position; The magnetic member is connected to a predetermined position of the optical fiber, and the magnetic member can generate a positional shift using magnetic force so that the Bragg grating at the predetermined position generates a bending deformation perpendicular to the predetermined direction.

[0008] In one embodiment, the optical fiber sensor further includes a bendable support beam, the optical fiber and the magnetic member are both connected to the support beam, and the optical fiber extends in the same direction as the support beam.

[0009] In one embodiment, the support beam is located on a side of the optical fiber that is away from the magnetic member, or The support beam is located on the side of the optical fiber facing the magnetic member, and is located between the optical fiber and the magnetic member.

[0010] In one embodiment, two optical fibers are provided, the two optical fibers are connected in parallel to opposite sides of the support beam, and the two Bragg gratings in the two optical fibers are arranged opposite each other, and the magnetic member is connected to the side of one of the optical fibers away from the support beam.

[0011] In one embodiment, the optical fiber sensor further includes a spacer for separating the magnetic member from the optical fiber arranged in close proximity to the magnetic member, the spacer being connected between the magnetic member and the support beam.

[0012] In one embodiment, a mounting groove extending along the predetermined direction is opened on one side of the spacer facing the magnetic member, the optical fiber arranged close to the magnetic member is inserted into the mounting groove, and the notch of the mounting groove is higher than the surface of the optical fiber.

[0013] In one embodiment, the optical fiber sensor further includes a mounting body, and both ends of the support beam are respectively connected to the mounting body.

[0014] In one embodiment, a mounting cavity is opened inside the mounting body, the magnetic member, the optical fiber and the support beam are all accommodated in the mounting cavity, and both ends of the support beam are fixedly connected to the cavity wall of the mounting cavity.

[0015] In one embodiment, the magnetic member and the optical fiber are connected and fixed by an adhesive structure.

[0016] A second object of the present application is to provide a magnetic field intensity measuring device including a light source, a fiber Bragg grating demodulator, and any of the optical fiber sensors described above, wherein the light source and the fiber Bragg grating demodulator are each connected to the optical fiber. [Effects of the Invention]

[0017] The advantageous effects of the optical fiber sensor and magnetic field strength measuring device of the present application over the prior art are that, compared to the prior art, the optical fiber sensor and magnetic field strength measuring device of the present application adopt a coupling between a magnetic member and an optical fiber, and connect the magnetic member to the position of the Bragg grating of the optical fiber. When the optical fiber sensor is placed in a magnetic field, the magnetic member can be moved by magnetic force, causing the optical fiber and the Bragg grating to bend and deform. The Bragg grating will then be affected by the change in stress, and the optical wavelength of the reflected wave will change accordingly. The fiber Bragg grating demodulator can analyze the change in wavelength of the reflected wave to calculate the magnetic field strength. The optical fiber is an electrical insulator, and the Bragg grating is made of an electrically insulating material, so no current passes through the optical fiber and the optical fiber can be electrically isolated, and the optical fiber and Bragg grating are not affected by electromagnetic interference and radio frequency interference, which is advantageous to improving the sensing or measurement accuracy of the optical fiber sensor.

[0018] Furthermore, this optical fiber sensor has a simple structure. Simply by connecting a magnetic member to the position of the optical fiber where the Bragg grating is formed, stress changes can be generated in the Bragg grating by moving the magnetic member, and the changed wavelength of the reflected light wave can be collected to analyze the magnetic field strength. This eliminates the need for a current-carrying conductor and the need for an additional current generator to supply current, which is advantageous in reducing production costs. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a structural schematic diagram 1 of an optical fiber sensor according to an embodiment of the present application. [Figure 2] 1 is a schematic diagram illustrating bending deformation of an optical fiber sensor according to an embodiment of the present invention in a magnetic field when in use. [Figure 3] 1 is a schematic diagram of the internal structure of an optical fiber in an optical fiber sensor according to an embodiment of the present application. [Figure 4] 2 is a structural schematic diagram 2 of an optical fiber sensor according to an embodiment of the present application. [Figure 5] 3 is a structural schematic diagram 3 of an optical fiber sensor according to an embodiment of the present application. [Figure 6] 4 is a structural schematic diagram 4 of an optical fiber sensor according to an embodiment of the present application. [Figure 7] FIG. 7 is a plan view of FIG. [Figure 8] FIG. 7 is a structural schematic diagram of the connection between the spacer and the support beam in FIG. 6. [Figure 9] 7 is a schematic diagram showing bending deformation of the optical fiber sensor in FIG. 6 in a magnetic field when in use. DETAILED DESCRIPTION OF THE INVENTION

[0020] In order to more clearly explain the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings that need to be used to describe the embodiments of the present application or the prior art. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can also obtain other drawings based on these drawings without any creative work.

[0021] Hereinafter, the embodiments of the present application will be described in detail, and examples of the embodiments are shown in the drawings, and the same or similar reference numerals throughout refer to the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are illustrative and are intended to explain the present application, but should not be understood as limiting the present application.

[0022] In the description of this application, as will be understood, the orientations or positional relationships indicated by the terms "length," "width," "top," "bottom," "upward," "vertical," "horizontal," "bottom," "inside," "outside," "inner," "outer," "outside," etc. are based on the orientations or positional relationships shown in the drawings, and are merely for the convenience and simplification of the description of this application, and do not indicate or imply that the specified device or element must have a particular orientation or be configured and operated in a particular orientation, and therefore should not be understood as a limitation on the application.

[0023] Additionally, the terms "first," "second," etc. are merely descriptive and should not be understood as indicating or implying relative importance or the number of technical features shown. Thus, a feature qualified as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of this application, "plurality" means two or more, unless otherwise specified.

[0024] In this application, unless otherwise clearly specified or limited, the terms "attached," "communicating," "connected," "fixed," etc. should be understood in a broad sense, and may refer to, for example, a fixed connection, a detachable connection, or an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, an internal communication between two elements, or an interactive relationship between two elements. Those skilled in the art can understand the specific meanings of the above terms in this application according to specific circumstances.

[0025] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be described in more detail below with reference to the drawings and examples.

[0026] As shown in Figures 1, 2 and 3, an embodiment of the present application provides an optical fiber sensor, which includes an optical fiber 2 and a magnetic member 1, wherein at least one optical fiber 2 is provided, the optical fiber 2 extends along a predetermined direction, has a predetermined position along the extension length of the optical fiber 2, a Bragg grating 21 is formed at the predetermined position, the magnetic member 1 is connected to a predetermined position of the optical fiber 2, and the magnetic member 1 can be displaced by magnetic force so that the Bragg grating 21 at the predetermined position generates a bending deformation perpendicular to the predetermined direction.

[0027] Specifically, the optical fiber 2 is an abbreviation for light guide fiber, and is a glass or plastic fiber that can be a light-conducting device. The transmission principle is total internal reflection of light. The diameter of the optical fiber 2 is 125 μm or less. The optical fiber 2 is an electrical insulator, so that no current passes through the optical fiber 2. The optical fiber 2 can be electrically isolated, and is not susceptible to electromagnetic interference and radio frequency interference.

[0028] The optical fiber 2 extends along a predetermined direction to form a strip-shaped or linear structure, the optical fiber 2 has a certain elasticity or flexibility, and when the optical fiber 2 is subjected to an external force approximately perpendicular to the length direction (predetermined direction) of the optical fiber 2, the optical fiber 2 can bend and deform in a direction perpendicular to the predetermined direction, and a Bragg grating 21 is formed in the central part of the extension length of the optical fiber 2, and the Bragg grating 21 is formed at a predetermined position on the optical fiber 2, and the predetermined position is located in the central region of the extension length of the optical fiber 2.

[0029] The Bragg grating 21 is an optical fiber Bragg grating with a uniformly matched grating pitch, which means that the reflected wavelength is very small and the distance between the reflection points of the Bragg grating 21 is always equal. Such a grating contains countless reflection points that can reflect specific wavelengths, and by accurately matching the distance between the two reflection points, lightwave signals that satisfy the Bragg condition are reflected by the grating, while signals of other wavelengths are basically not reflected.

[0030] The Bragg grating 21 is formed on the optical fiber 2 to produce a fiber Bragg grating, which is abbreviated as FBG and collectively referred to as Fiber Bragg Grating, that is, a grating formed in the core with a periodically distributed spatial phase, whose function is to form a narrow-band (transmission or reflection) filter or reflector in the core. In this embodiment, Bragg gratings 21 with different wavelengths or periods may be connected in series in the same optical fiber 2.

[0031] As shown in Figure 3, fiber Bragg grating is made by exposing a small portion of a light-sensitive optical fiber 2 to a light wave with a periodic distribution of light intensity through holographic interferometry or phase masking. In this way, the optical refractive index of the optical fiber 2 changes permanently according to the light wave intensity irradiated onto it. The periodic change of the optical refractive index made in this way is called fiber Bragg grating.

[0032] As shown in Figure 3, when a broadband beam 7 is propagated through a fiber Bragg grating, each portion of the optical fiber 2 with its optical refractive index changed will reflect only light waves of a specific wavelength, which is called the Bragg wavelength. Due to this characteristic, the fiber Bragg grating will reflect only light waves of a specific wavelength, while light waves of other wavelengths will be propagated.

[0033] When the Bragg grating 21 is subjected to stress or temperature changes, the grating pitch changes and the optical wavelength of the reflected wave also changes accordingly, reflecting different wavelengths which can be collected and analyzed by a detection element (i.e., a fiber Bragg grating demodulator, described below).

[0034] The magnetic member 1 has magnetism, is attracted or repelled by an external magnetic field, and can be further moved by the magnetic force. The magnetic member 1 may include a structural member made of a metal material such as iron, nickel, or cobalt, or an alloy structural member made of the above metal material. When the magnetic member 1 is made of a nickel material, the corrosion resistance of the magnetic member 1 is stronger.

[0035] The magnetic member 1 is connected and fixed at a predetermined position on the optical fiber 2, i.e., at the position where the Bragg grating 21 is provided, and the magnetic member 1 and the optical fiber 2 can be connected by an adhesive structure to form the whole, and the adhesive structure can be made of an adhesive.

[0036] When the optical fiber sensor in this embodiment is used, the optical fiber 2 is respectively connected to a light source and a detection element for detecting the wavelength of the reflected light wave 8, the light source can generate a narrowband beam 7, the detection element can adopt a fiber Bragg grating demodulator, which can measure the light wave wavelength of the independent reflected wave, and the fiber Bragg grating demodulator analyzes the change value of the wavelength of the reflected light wave 8 reflected by the Bragg grating 21 to correspondingly obtain the strength of the magnetic field.

[0037] During detection, the optical fiber sensor is placed in a magnetic field, and the optical fibers 2 on both sides of the Bragg grating 21 have relative fixed points in the magnetic field, preventing the optical fiber 2 from moving as a whole after receiving a force. The magnetic field can be generated by a magnetic generator such as a magnet or electromagnet. As shown in FIG. 2, the magnetic field is generated by a magnet 6, which is located on the side of the optical fiber 2 and is installed opposite the magnetic member 1. A magnetic induction line passes through a predetermined position of the magnetic member 1 and the optical fiber 2 approximately perpendicularly. That is, the magnetic induction line passes through a predetermined position of the magnetic member 1 and the optical fiber 2 in a direction approximately perpendicular to the predetermined direction. The magnetic member 1 moves and displaces under the action of the magnetic field, and the magnetic member 1 moves in the predetermined direction. When the magnetic member 1 moves in a direction approximately perpendicular to the direction of the optical fiber 2, the magnetic member 1 bends the optical fiber 2 and the Bragg grating 21 in the optical fiber 2. After the Bragg grating 21 is bent, the Bragg grating 21 is subjected to an acting force, i.e., the Bragg grating 21 is affected by a change in stress, and the wavelength of the reflected light wave 8 changes. The Bragg grating demodulator collects the wavelength of the emitted light wave after the change, analyzes the change in the emitted wavelength before and after the bending deformation of the Bragg grating 21, and further analyzes and obtains the strength of the magnetic field. The specific analysis process of the magnetic field strength is the operating principle of a conventional fiber Bragg grating modulator, and will not be described here.

[0038] In this embodiment, the optical fiber sensor adopts a coupling between a magnetic member 1 and an optical fiber 2, and the magnetic member 1 is connected to the position of the Bragg grating 21 of the optical fiber 2. When the optical fiber sensor is placed in a magnetic field, the magnetic member 1 will move due to magnetic force, causing the optical fiber 2 and the Bragg grating 21 to bend and deform. The Bragg grating 21 will then be affected by the change in stress, and the optical wavelength of the reflected wave will change accordingly. The fiber Bragg grating demodulator can analyze the change in wavelength of the reflected wave to calculate the strength of the magnetic field. Here, the optical fiber 2 is an electrical insulator, and the Bragg grating 21 is made of an electrically insulating material, so that no current passes through the optical fiber 2 and the optical fiber 2 can be electrically isolated. Therefore, the optical fiber 2 and the Bragg grating 21 are not affected by electromagnetic interference and radio frequency interference, which is advantageous to improving the sensing or measurement accuracy of the optical fiber sensor.

[0039] Furthermore, this optical fiber sensor has a simple structure, and it is only necessary to connect the magnetic member 1 to the position of the optical fiber 2 where the Bragg grating 21 is formed. By moving the magnetic member 1, stress changes are generated in the Bragg grating 21, and the wavelength of the changed reflected light wave 8 can be collected to analyze the strength of the magnetic field. This eliminates the need for a current-carrying conductor and the need for an additional current generator to supply current, which is advantageous in reducing production costs.

[0040] In one embodiment, the optical fiber 2 can be made of silicon dioxide material, which has high temperature resistance and is a passive, inert solid material that is less susceptible to temperature changes, allowing the optical fiber sensor to be used in temperature environments of at least 100°C or higher, and thus providing a wider range of applicable environmental temperatures than conventional technologies.

[0041] In one embodiment, as shown in Figures 4, 5 and 6, the optical fiber sensor further includes a bendable support beam 4, and the optical fiber 2 and the magnetic member 1 are both connected to the support beam 4, and the optical fiber 2 extends in the same direction as the support beam 4.

[0042] Specifically, the support beam 4 extends along a predetermined direction and is formed into a strip, that is, the central axis of the support beam 4 extends along a predetermined direction, the extension direction of the support beam 4 is the same as the extension direction of the optical fiber 2, and the cross-section of the support beam 4 is circular, elliptical, polygonal, etc., as shown in Figure 3, the cross-section of the support beam 4 is rectangular, the outer surface of the support beam 4 has an attachment plane, the optical fiber 2 is attached to the attachment plane, and the optical fiber 2 can be fixedly connected to the attachment plane of the support beam 4 by an adhesive.

[0043] The support beam 4 is a non-magnetic structural member, and is not magnetic and is not affected by magnetic field forces. The mass of the support beam 4 should be as light as possible, so the support beam 4 is made of a lightweight material, such as aluminum. The support beam 4 is elastic, and when the support beam 4 is subjected to a force approximately perpendicular to a predetermined direction, the support beam 4 can undergo bending deformation approximately perpendicular to the predetermined direction.

[0044] The optical fiber 2 may be attached to either side of the support beam 4, and the magnetic member 1 and the optical fiber 2 may be connected to the same side of the support beam 4 or to different sides of the support beam 4. When the magnetic member 1 and the optical fiber 2 are connected to the same side of the support beam 4, the optical fiber 2 is located between the magnetic member 1 and the support beam 4, and the optical fiber 2, the magnetic member 1 and the support beam 4 may be bonded together with an adhesive to form an integrated structure.

[0045] In this embodiment, the support beam 4 mainly plays a supporting role for the optical fiber 2, and the Bragg grating 21 in the optical fiber 2 is located in the central region of the support beam 4. The magnetic field generates a magnetic force on the magnetic member 1, and when the magnetic member 1 moves, the magnetic member 1 bends the support beam 4. Since the optical fiber 2 is connected to the support beam 4, the optical fiber 2 and the support beam 4 bend and deform synchronously. Furthermore, the Bragg grating 21 in the optical fiber 2 is affected by the stress change, and the wavelength of the reflected light wave 8 changes accordingly. The fiber Bragg grating demodulator analyzes the change in the wavelength of the reflected wave to calculate the strength of the magnetic field.

[0046] Furthermore, the sensitivity of the optical fiber sensor in this embodiment can be adjusted by adjusting the thickness and width of the support beam 4 in the direction perpendicular to the predetermined direction. The thinner the support beam 4, the higher the sensitivity of the sensor. The narrower the width of the support beam 4, the higher the sensitivity of the sensor. The magnetic member 1 can also have a sheet-like structure. The larger the surface area of ​​the magnetic member 1, the higher the sensitivity of the sensor. In particular, the wider the magnetic member 1 is in the width direction perpendicular to the predetermined direction, the higher the sensitivity of the sensor. Adjustable sensitivity allows users to customize and select the optical fiber sensor. The sensor's sensitivity to magnetic field strength is determined by the size and physical parameters of the components. The sensitivity of the optical fiber sensor can also be reduced by thickening, shortening, or widening the support beam 4. These factors are the basis for initializing different measurement range parameters of the optical fiber sensor.

[0047] Regarding the directionality of the optical fiber sensor in this embodiment, the directionality of the sensor can be adjusted by adjusting the ratio between the surface area and the thickness of the magnetic member 1, and the higher the ratio between the surface area and the thickness of the magnetic member 1, the higher the directionality. The optical fiber sensor is designed to have the highest directionality in the upward direction (toward the magnet 6) as well as in the direction of the support beam 4.

[0048] In the optical fiber sensor of this embodiment, the purpose of reducing mechanical vibration interference can be achieved by maximizing the thickness of the support beam 4, minimizing the weight of the support beam 4, or minimizing the weight of the magnetic member 1.

[0049] In one embodiment, as shown in FIG. 4, the support beam 4 is located on the side of the optical fiber 2 away from the magnetic member 1, i.e., the optical fiber 2 is located between the magnetic member 1 and the support beam 4, and the magnetic member 1, the optical fiber 2 and the support beam 4 are bonded together with an adhesive to form a whole.

[0050] In this embodiment, both ends of the support beam 4 can be fixedly installed relative to each other in the magnetic field. Specifically, both ends of the support beam 4 can be fixedly connected to other fixed structures in the magnetic field. When the upper side of the magnetic member 1 (i.e., the side of the magnetic member 1 away from the support beam 4) is subjected to the attractive force of the magnetic field, the support beam 4 and the optical fiber 2 are bent outward toward the upper side of the magnetic member 1, the upper side of the support beam 4 (the side of the support beam 4 facing the magnetic member 1) is bent and a tensile force is applied, and the lower side away from the upper side of the support beam 4 is subjected to pressure. That is, the upper side of the support beam 4 is subjected to positive strain, and the lower side of the support beam 4 is subjected to negative strain. The optical fiber 2 attached to the upper side of the support beam 4 and the Bragg grating 21 thereon are subjected to positive strain, and the optical wavelength of the reflected wave changes accordingly. The stronger the magnetic field, the greater the change in the optical wavelength of the reflected wave, and the larger the wavelength shift width.

[0051] In one embodiment, as shown in FIG. 5, the support beam 4 is located on the side of the optical fiber 2 facing the magnetic member 1, and is located between the optical fiber 2 and the magnetic member 1, and the magnetic member 1, the optical fiber 2 and the support beam 4 are bonded together with an adhesive to form a whole.

[0052] In this embodiment, both ends of the support beam 4 can be fixedly installed relative to each other in the magnetic field; specifically, both ends of the support beam 4 can be fixedly connected to other fixed structures in the magnetic field; the support beam 4 is connected between the optical fiber 2 and the magnetic member 1; when the upper side of the magnetic member 1 (i.e., the side of the magnetic member 1 away from the support beam 4) is subjected to the attractive force of the magnetic field, the support beam 4 and the optical fiber 2 bend convexly outward toward the upper side of the magnetic member 1; the upper side of the support beam 4 (the side of the support beam 4 facing the magnetic member 1) bends and is subjected to a tensile force, and the lower side away from the upper side of the support beam 4 is subjected to pressure; that is, the upper side of the support beam 4 is subjected to positive strain and the lower side of the support beam 4 is subjected to negative strain; the optical fiber 2 is connected to the lower side of the support beam 4 (the side of the support beam 4 away from the magnetic member 1); the optical fiber 2 attached to the lower side of the support beam 4 and the Bragg grating 21 thereon are subjected to the negative strain, and the optical wavelength of the reflected wave changes accordingly. The stronger the magnetic field, the greater the change in the light wave wavelength of the reflected wave, and the greater the wavelength shift width.

[0053] 6 and 7, two optical fibers 2 are provided, and two Bragg gratings 21 in the two optical fibers 2 are provided facing each other, and the magnetic member 1 is connected to the side of one of the optical fibers 2 that is away from the support beam 4. The two optical fibers 2 are each connected to a fiber Bragg grating demodulator, and by comprehensively analyzing the changes in the lightwave wavelength of the reflected waves that have passed through the two optical fibers 2, it is possible to perform superposition analysis on the lightwave wavelengths of the reflected waves that have passed through the two optical fibers 2, which allows for more accurate calculation of the magnetic field strength and improves measurement accuracy.

[0054] Here, for ease of explanation, in this embodiment, the two opposing side surfaces of the support beam 4 are defined as the first side surface and the second side surface, respectively, and the two optical fibers 2 are defined as the first optical fiber 22 and the second optical fiber 23, respectively.

[0055] Specifically, the two optical fibers 2 are connected in parallel to opposite sides of the support beam 4, the first optical fiber 22 is connected to the first side of the support beam 4, the second optical fiber 23 is connected to the second side of the support beam 4, the magnetic member 1 is connected to the first side of the support beam 4, the first optical fiber 22 is positioned between the magnetic member 1 and the first side of the support beam 4, and the magnetic member 1, the first optical fiber 22, the second optical fiber 23 and the support beam 4 are bonded and fixed together with an adhesive to form an integrated structure.

[0056] Both ends of the support beam 4 can be relatively fixedly installed in the magnetic field; specifically, both ends of the support beam 4 may be fixedly connected to other fixed structures in the magnetic field, and the first optical fiber 22, the second optical fiber 23 and the magnetic member 1 are located in the central region of the extension length of the support beam 4.

[0057] In this embodiment, when the upper side of the magnetic member 1 (i.e., the side of the magnetic member 1 facing away from the support beam 4) is subjected to the attractive force of the magnetic field, the support beam 4, the first optical fiber 22, and the second optical fiber 23 bend convexly outward toward the upper side of the magnetic member 1, so that the upper side of the support beam 4 (the side of the support beam 4 facing the magnetic member 1) bends and is subjected to a tensile force, and the lower side of the support beam 4 facing away from the upper side (the side of the support beam 4 facing away from the magnetic member 1) is subjected to pressure; in other words, the upper side of the support beam 4 is subjected to positive strain, and the lower side of the support beam 4 is subjected to negative strain, and the directions of the strains applied to the upper and lower sides of the support beam 4 are reversed.

[0058] Therefore, the first optical fiber 22 and the Bragg grating 21 mounted on it, located above the support beam 4, are subjected to positive strain, causing the wavelength of the reflected wave to shift in a positive direction. The second optical fiber 23 and the Bragg grating 21 mounted on it, located below the support beam 4, are subjected to negative strain, causing the wavelength of the reflected wave to shift in a negative direction. The positive and negative wavelength shifts of the reflected wave are opposite in direction but have the same magnitude. Therefore, by using two optical fibers 2 in this embodiment, the change in the wavelength of the reflected wave can be doubled compared to using a single optical fiber 2. The signal transmitted by the sensor to the fiber Bragg grating demodulator is doubled, resulting in a doubled signal change range. This allows the fiber Bragg grating sensor to more accurately calculate the magnetic field strength based on the wavelength change data of the reflected wave, which is beneficial to improving measurement accuracy. The stronger the magnetic field, the greater the change in the wavelength of the reflected wave, resulting in a larger wavelength shift.

[0059] In addition, by adopting optical fiber sensors in which the two optical fibers 2 are arranged symmetrically on both sides of the support beam 4 so as to separate them, the influence of temperature on the lightwave wavelengths of the two reflected waves can be offset, which is advantageous in improving the accuracy of the collected and measured data.

[0060] Furthermore, the first optical fiber 22 and the second optical fiber 23 are respectively arranged on the upper and lower sides of the support beam 4, and this arrangement method allows the temperature effects on the first optical fiber 22 and the second optical fiber 23 to cancel each other out, so that the above structure can form temperature compensation, and the entire structure has good temperature difference stability and can withstand higher temperature environments.

[0061] In one embodiment, as shown in Figures 4-8, the optical fiber sensor further includes a spacer 3 for separating the magnetic member 1 from the optical fiber 2 arranged adjacent to the magnetic member 1, the optical fiber 2 arranged adjacent to the magnetic member 1 being a first optical fiber 22, and the spacer 3 being connected between the magnetic member 1 and the support beam 4.

[0062] Specifically, the magnetic member 1 is sheet-shaped, and as shown in Figures 6, 7 and 8, the outer contour shape of the cross section of the magnetic member 1 is circular, the spacer 3 is sheet-shaped, one side of the spacer 3 is connected to one side (lower side) of the magnetic member 1 facing the optical fiber 2 (in this embodiment, the optical fibers 2 described later all refer to the first optical fiber 22), and the other side of the spacer 3 is connected to one side (upper side) of the support beam 4 facing the optical fiber 2, the spacer 3 is located between the magnetic member 1 and the support beam 4, the thickness of the spacer 3 is greater than the diameter of the optical fiber 2, the spacer 3 can avoid the optical fiber 2 and prevent the optical fiber 2 from coming into direct contact with the magnetic member 1.

[0063] In this embodiment, by adding a spacer 3, the spacer 3 is connected between the magnetic member 1 and the support beam 4, and the spacer 3 is installed away from the optical fiber 2, preventing the optical fiber 2 from coming into direct contact with the magnetic member 1 and serving to protect the optical fiber 2.

[0064] In one embodiment, as shown in Figures 7 and 8, a mounting groove 31 extending along a predetermined direction is opened on one side of the spacer 3 facing the magnetic member 1, the optical fiber 2 installed adjacent to the magnetic member 1 is inserted into the mounting groove 31, and the notch of the mounting groove 31 is higher than the surface of the optical fiber 2.

[0065] In this embodiment, the optical fiber 2 below refers to the first optical fiber 22 in all cases.

[0066] Specifically, a mounting groove 31 for accommodating the optical fiber 2 is provided on the side of the spacer 3 that is connected to the magnetic member 1. To prevent the optical fiber 2 accommodated in the mounting groove 31 from coming into contact with the magnetic member 1 on the surface of the spacer 3, the depth of the mounting groove 31 is greater than the diameter of the optical fiber 2. When the optical fiber 2 is inserted into the mounting groove 31, the notch in the mounting groove 31 is higher than the surface of the optical fiber 2, forming a gap between the surface of the optical fiber 2 and the underside of the magnetic member 1. This prevents the optical fiber 2 from coming into direct contact with the magnetic member 1 and serves to protect the optical fiber 2.

[0067] In this embodiment, as shown in Figures 7 and 8, the mounting groove 31 in the spacer 3 may be a through groove, and the bottom of the mounting groove 31 may extend to the surface of the support beam 4, so that the spacer 3 is divided into two parts, and the two parts of the spacer 3 are located on both sides of the optical fiber 2, respectively. The structural form of the spacer 3 is not limited to the form listed in this embodiment, and any form of spacer 3 that can separate the optical fiber 2 and the magnetic member 1 is within the scope of protection of the present application.

[0068] In one embodiment, as shown in FIGS. 4-9, the optical fiber sensor further includes a mounting body 5, and both ends of the support beam 4 are connected to the mounting body 5, respectively.

[0069] In this embodiment, the mounting body 5 is a support structure for fixing the support beam 4, and the support beam 4 is fixedly or detachably connected to the mounting body 5. By connecting both ends of the support beam 4 to the mounting body 5, both ends of the support beam 4 are fixed relatively within a magnetic field, and when subjected to the action of a magnetic field force, the support beam 4 can bend and deform in the middle.

[0070] In one embodiment, as shown in Figures 4-9, a mounting cavity 51 is opened inside the mounting body 5, the magnetic member 1, the optical fiber 2 and the support beam 4 are all accommodated in the mounting cavity 51, and both ends of the support beam 4 are fixedly connected to the cavity wall of the mounting cavity 51, respectively.

[0071] Specifically, the mounting body 5 can adopt a housing or frame-type structure, and the exterior of the mounting body 5 can be cylindrical or cubic. The mounting body 5 can be made of plastic material to reduce electromagnetic interference and radio frequency interference. A mounting cavity 51 is opened inside the mounting body 5, so that the entire structure consisting of the magnetic member 1, the optical fiber 2, the support beam 4, and the spacer 3 is accommodated in the mounting cavity 51, and both ends of the support beam 4 extend to the cavity wall of the mounting cavity 51 and are fixedly connected to the cavity wall of the mounting cavity 51.

[0072] In this embodiment, the entire structure of the magnetic member 1, the optical fiber 2, and the support beam 4 is accommodated in the mounting cavity 51 inside the mounting body 5, which can serve to protect the entire structure of the magnetic member 1, the optical fiber 2, and the support beam 4. In addition, the design of the mounting body 5 makes it more convenient to move and use the entire optical fiber sensor.

[0073] As described above, the present optical fiber sensor can be used repeatedly and can transmit over long distances, and has the advantages of electrical isolation, high temperature and pressure resistance, and long-term stability. Compared with conventional electronic sensors, the most notable feature of the present optical fiber sensor is that it is based on an optical fiber Bragg grating, which overcomes the problems of electromagnetic interference and radio frequency interference that often occur in the field.

[0074] A second object of the present application is to provide a magnetic field strength measuring device, which includes a light source, a fiber Bragg grating demodulator, and an optical fiber sensor in the above embodiment, and the light source and the fiber Bragg grating demodulator are each connected to an optical fiber 2.

[0075] Specifically, the light source can emit and generate a beam 7 to generate a light wave, the light source is connected to the optical fiber 2 and used to input a light wave or a light wave signal into the optical fiber 2, and the fiber Bragg grating demodulator is used to receive the wavelength signal of the light wave 8 reflected by the Bragg grating 21 and obtain the magnetic field intensity through analysis and calculation.

[0076] In this embodiment, the optical fiber sensor in this magnetic field intensity measurement device adopts a coupling between a magnetic member 1 and an optical fiber 2, and the magnetic member 1 is connected to the position of the Bragg grating 21 of the optical fiber 2. When the optical fiber sensor is placed in a magnetic field, the magnetic member 1 will move due to magnetic force, causing the optical fiber 2 and the Bragg grating 21 to bend and deform. The Bragg grating 21 will then be affected by the change in stress, and the optical wavelength of the reflected wave will change accordingly. The fiber Bragg grating demodulator can then analyze the change in wavelength of the reflected wave to calculate the magnetic field strength. Here, the optical fiber 2 is an electrical insulator, and the Bragg grating 21 is made of an electrically insulating material, so that no current passes through the optical fiber 2 and the optical fiber 2 can be electrically isolated. Therefore, the optical fiber 2 and the Bragg grating 21 are not affected by electromagnetic interference and radio frequency interference, which is advantageous to improving the sensing or measurement accuracy of the optical fiber sensor.

[0077] This magnetic field strength measurement device utilizes wireless transmission technology to develop an online system, allowing the optical fiber sensor to be attached to mobile vehicles, drones, and other devices to calculate the overall magnetic field strength. In the short term, this optical fiber sensor can be tested and implemented in a variety of critical experimental and engineering scenarios where electromagnetic and radio frequency interference are severe. Organizations that need to measure magnetic fields in high electromagnetic interference and high ambient temperature environments, as well as organizations where sensors are distributed synchronously over a large area, are potential targets. In the long term, this optical fiber sensor can be produced on a large scale and used by professionals.

[0078] The above are merely preferred embodiments of the present invention, and specifically describe only the technical principles of the present application. However, these descriptions are merely for the purpose of interpreting the principles of the present application, and should not be construed as limiting the scope of protection of the present application in any manner. Based on the interpretation of this specification, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application, as well as other specific embodiments of the present application that can be conceived by those skilled in the art without requiring creative efforts, should all be included in the scope of protection of the present application. [Explanation of symbols]

[0079] 1: Magnetic material 2: Optical fiber 21: Bragg grating 22: First optical fiber 23: Second optical fiber 3: Spacer 31: Mounting groove 4: Support beam 5: Mounting body 51: Mounting cavity 6: Magnet 7: Beam 8: Reflected light waves

Claims

1. 1. An optical fiber sensor, comprising: the optical fiber sensor includes an optical fiber and a magnetic member; At least one optical fiber is provided, the optical fiber extending in a predetermined direction, the optical fiber having a predetermined position along its extension length, and a Bragg grating formed at the predetermined position; The magnetic member is connected to a predetermined position of the optical fiber, and the magnetic member can generate a positional displacement by a magnetic force so that the Bragg grating at the predetermined position generates a bending deformation perpendicular to the predetermined direction.

1. An optical fiber sensor comprising:

2. 2. The optical fiber sensor according to claim 1, further comprising a bendable support beam, wherein the optical fiber and the magnetic member are both connected to the support beam, and the optical fiber extends in the same direction as the support beam.

3. the support beam is located on a side of the optical fiber away from the magnetic member, or 3. The optical fiber sensor according to claim 2, wherein the support beam is located on a side of the optical fiber facing the magnetic member, and is located between the optical fiber and the magnetic member.

4. The optical fiber sensor according to claim 2, characterized in that two optical fibers are provided, the two optical fibers are connected in parallel to opposite sides of the support beam, the two Bragg gratings in the two optical fibers are arranged opposite each other, and the magnetic member is connected to the side of one of the optical fibers away from the support beam.

5. 5. The optical fiber sensor according to claim 4, further comprising a spacer for separating the magnetic member from the optical fiber provided in close proximity to the magnetic member, the spacer being connected between the magnetic member and the support beam.

6. 6. The optical fiber sensor according to claim 5, wherein a mounting groove extending along the predetermined direction is formed on one side of the spacer facing the magnetic member, the optical fiber provided adjacent to the magnetic member is inserted into the mounting groove, and a notch in the mounting groove is higher than a surface of the optical fiber.

7. 7. The optical fiber sensor according to claim 2, further comprising a mounting body, wherein both ends of the support beam are connected to the mounting body.

8. The optical fiber sensor according to claim 7, characterized in that an installation cavity is opened inside the installation body, the magnetic member, the optical fiber and the support beam are all accommodated in the installation cavity, and both ends of the support beam are fixedly connected to the cavity wall of the installation cavity.

9. 7. The optical fiber sensor according to claim 1, wherein the magnetic member and the optical fiber are connected and fixed by an adhesive structure.

10. A magnetic field strength measuring device, 10. A magnetic field intensity measuring device comprising: a light source; a fiber Bragg grating demodulator; and the optical fiber sensor according to claim 1, wherein the light source and the fiber Bragg grating demodulator are each connected to the optical fiber.

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