Optical fiber magnetic field sensor, preparation method thereof, sensing device and magnetic field detection method

Abstract

The invention provides an optical fiber magnetic field sensor and a preparation method thereof, a sensing device and a magnetic field detection method, the optical fiber magnetic field sensor comprises an optical fiber, a magnetic strip and a fixing piece, the optical fiber magnetic field sensor comprises the optical fiber, the magnetic strip and the fixing piece, at least part of the optical fiber is bent to form a bent part, and the magnetic strip is fixed to the fixing piece. The bending part is arranged on the optical fiber, so that the bending radius of the optical fiber is changed, then the refractive index of the optical fiber is changed, spectrogram data of spectrum drift can be obtained, and then a spectrogram for determining the size of a magnetic field by representing the wavelength drift amount in a spectrum is obtained. Compared with the prior art, the technical scheme of the invention has the advantages of simple preparation, flexible regulation and high measurement precision.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic field sensors, and in particular to an optical fiber magnetic field sensor and a preparation method thereof, a sensing device, and a magnetic field detection method. Background Art

[0002] Magnetic field sensors play an important role in aerospace, medical instruments, consumer electronics and other fields. Traditional magnetic field sensors are susceptible to electromagnetic interference and have large temperature drift. Optical fiber has the advantages of high temperature resistance, corrosion resistance, and electromagnetic interference resistance, so optical fiber sensors have received extensive attention and research. At present, optical fiber magnetic field sensors mainly include principles and preparation methods based on the Faraday rotation effect of magneto-optical crystals, based on magnetostrictive materials and optical fiber layer winding, and based on magnetic fluid and optical fiber composite packaging. However, the above methods have problems such as complex preparation process, high cost, or additional packaging process. Therefore, there is an urgent need to improve the existing magnetic field sensors. Summary of the invention

[0003] One purpose of the present application is to provide an optical fiber magnetic field sensor and a preparation method thereof, a sensing device, and a magnetic field detection method, which aims to solve the technical problems of complex preparation process and high cost of optical fiber magnetic field sensors in the prior art.

[0004] To achieve the above object, a first aspect of an embodiment of the present application provides an optical fiber magnetic field sensor based on macrobending loss, the optical fiber magnetic field sensor comprising:

[0005] an optical fiber, wherein the optical fiber is at least partially bent to form a bent portion;

[0006] A magnetic strip, two ends of which are connected to the bent portion;

[0007] A fixing member is connected to the optical fiber and keeps the bent portion bent.

[0008] Compared with the prior art, the optical fiber magnetic field sensor provided by the embodiment of the present invention has the following beneficial effects: the optical fiber magnetic field sensor provided by the present invention comprises: an optical fiber, a magnetic strip, and a fixing member, wherein the optical fiber is at least partially bent to form a bending portion, and both ends of the magnetic strip are connected to the bending portion. The present invention provides a bending portion in the optical fiber, thereby changing the bending radius of the optical fiber and then changing the refractive index of the optical fiber, thereby obtaining spectrum graph data of spectral drift, and then obtaining a spectrum graph that determines the magnitude of the magnetic field by characterizing the wavelength drift in the spectrum, thereby realizing the detection of the magnitude of the magnetic field. Compared with the prior art, the technical solution of the present invention has the advantages of simple preparation, flexible regulation and high measurement accuracy.

[0009] In an implementation of the first aspect of the present application, the optical fiber includes a core and a cladding, and a refractive index N1 of the cladding is smaller than a refractive index N2 of the core.

[0010] Through the technical solution in this embodiment, the refractive index N1 of the cladding is significantly different from the refractive index N2 of the core, which is conducive to obtaining an easy-to-observe spectral drift diagram, and thus is conducive to obtaining a spectral diagram that characterizes the magnetic field size through the wavelength of the optical fiber magnetic field sensor.

[0011] In an implementation of the first aspect of the present application, the optical fiber is a quartz single-mode optical fiber, the diameter D1 of the quartz single-mode optical fiber is 125um, and the diameter D2 of the fiber core is 8-10um. Through the technical solution in this embodiment, the loss of the light source signal in the optical fiber can be reduced, which is conducive to improving the measurement accuracy of the optical fiber magnetic field sensor.

[0012] In an implementation of the first aspect of the present application, the magnetic strip is a flexible magnetic strip, and both ends of the flexible magnetic strip are connected to the curved portion by ultraviolet glue. Through the technical solution in this embodiment, the flexible magnetic strip can be better fixed to the curved portion.

[0013] In an implementation of the first aspect of the present application, the length of the flexible magnetic strip is 6 mm-10 mm, and the side length of the cross section of the magnetic strip is 0.2 mm to 1 mm.

[0014] In an implementation of the first aspect of the present application, the flexible magnetic strip includes magnetic nanoparticles, and the mass proportion of the magnetic nanoparticles is 10%-50%. Through the technical solution in this embodiment, the magnetic nanoparticles of the flexible magnetic strip have a higher mass proportion, so that the flexible magnetic strip can better sense the magnetic force of the magnetic field to be measured, thereby achieving the improvement of the magnetic field perception performance, which is conducive to improving the accuracy of the magnetic field detection of the optical fiber magnetic field sensor.

[0015] In an implementation of the first aspect of the present application, the bending radius of the bending portion is 8mm-13.5mm. Through the technical solution in this embodiment, the bending radius of the optical fiber can be adjusted, so as to facilitate the screening of the bending radius with a more obvious interference effect, which is conducive to improving the accuracy of magnetic field detection of the optical fiber magnetic field sensor.

[0016] In a second aspect, the present application proposes an optical fiber magnetic field sensing device, comprising the optical fiber magnetic field sensor described in any one of the above embodiments, and also comprising a laser light source and a spectrometer, wherein the laser light source and the spectrometer are respectively connected to the two ends of the optical fiber.

[0017] In a third aspect, the present application provides a method for preparing an optical fiber magnetic field sensor, which is used to prepare the optical fiber sensor as described in any one of the above embodiments, and the preparation method comprises the following steps:

[0018] Bend at least a portion of the optical fiber to form a bent portion, and adjustably connect the optical fiber to the fixing member;

[0019] Connecting a laser light source to one end of the optical fiber of the optical fiber magnetic field sensor, connecting a spectrometer to the other end of the optical fiber, controlling the laser light source to emit laser light to the optical fiber, and the spectrometer to receive the laser light transmitted through the optical fiber;

[0020] By tightening the optical fiber, the bending radius of the bending portion gradually changes within a set range;

[0021] A first optical spectrum diagram of different optical fiber bending radii of the optical fiber magnetic field sensor is obtained, and an optimal bending radius is determined according to a resonance peak in the first optical spectrum diagram.

[0022] The preparation method of the optical fiber magnetic field sensor in the embodiment of the present application dynamically adjusts the bending radius of the bending portion of the optical fiber to obtain a first spectrum diagram at different bending radii and different wavelengths, thereby determining the optimal bending radius through the resonant peak in the first spectrum diagram, which is beneficial to improving the perception performance of the optical fiber magnetic field sensor to the magnetic field to be measured, and is beneficial to improving the measurement accuracy of the optical fiber magnetic field sensor.

[0023] A fourth aspect of the present application provides a magnetic field detection method, using the optical fiber magnetic field sensor described in any one of the above embodiments, the magnetic field detection method comprising:

[0024] Acquire a second spectrum graph of the optical fiber magnetic field sensor in magnetic fields of different intensities;

[0025] Connecting a laser light source to one end of the optical fiber of the optical fiber magnetic field sensor, and connecting a spectrometer to the other end of the optical fiber;

[0026] Placing the optical fiber magnetic field sensor in the magnetic field to be measured;

[0027] Controlling the laser light source to emit laser light to the optical fiber, and the spectrometer to receive the laser light transmitted through the optical fiber to obtain measurement spectrum information;

[0028] The measured spectrum information is compared with the second spectrum diagram to determine the magnitude of the magnetic field to be measured.

[0029] The magnetic field detection method in the embodiment of the present application obtains a second spectrum diagram for characterizing the correspondence between wavelength and magnetic field intensity through an optimal bending radius. The magnetic field detection method uses actual magnetic field intensity data as calibration data and reference data, thereby improving the measurement accuracy of the magnetic field detection method. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0031] Figure 1 is a schematic diagram of an optical fiber magnetic field sensor provided by an embodiment of the present invention;

[0032] Figure 2 is a schematic diagram of the structure of an optical fiber magnetic field sensor device provided by an embodiment of the present invention;

[0033] Figure 3 is a flow chart of a method for preparing an optical fiber magnetic field sensor provided by an embodiment of the present invention;

[0034] Figure 4 A flow chart of a magnetic field detection method provided by an embodiment of the present invention;

[0035] Figure 5 A schematic diagram of an optical fiber magnetic field sensor at different bending radii provided by an embodiment of the present invention;

[0036] Figure 6 A first spectrum diagram corresponding to wavelength under different optical fiber bending radii provided by an embodiment of the present invention;

[0037] Figure 7 A second spectrum diagram of the optical fiber magnetic field sensor provided by an embodiment of the present invention under different magnetic fields;

[0038] Figure 8 A flow chart for preparing a flexible magnetic strip provided in an embodiment of the present invention.

[0039] Description of Figure Numbers:

[0040] Optical fiber magnetic field sensor 100; laser light source 200; spectrometer 300; optical fiber 10; first end 11; second end 12; flexible magnetic strip 20; fixing member 30; ultraviolet glue 40. DETAILED DESCRIPTION

[0041] In order to make the invention purpose, features and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the embodiments described below are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application. It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections.

[0042] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0043] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0044] As used in this specification and the appended claims, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting" depending on the context. Similarly, the phrase "if it is determined" or "if [the described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [the described condition or event] is detected" or "in response to detecting [the described condition or event]" depending on the context. In addition, in the description of the present application, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0047] As an important communication transmission medium, optical fiber has the advantages of high bandwidth, low loss, and anti-interference. However, optical fiber will also encounter some problems during use, one of which is macrobending loss. Macrobending loss refers to the loss of optical signals generated at the bends of optical fiber with large curvature radius. Macrobending loss is mainly caused by the scattering and escape of light at the bends of optical fiber. When light is transmitted in a curved optical fiber, due to the change in the propagation speed and direction of light in the medium, part of the light will escape from the optical fiber, causing the loss of the optical signal. In addition, the propagation of light in the optical fiber is by total reflection, and at the bend, the incident angle of the light will exceed the critical angle of total reflection, resulting in scattering, which will also cause the loss of the optical signal.

[0048] The inventors have found that when the optical signal is transmitted in the bent part of the optical fiber, a part of it will leak from the core to the cladding and couple back to the core in the non-bent part. Since the refractive index of the core and the cladding is different, the optical signal interferes in the bent part of the optical fiber. As the bending radius gradually decreases, the interference effect of the spectrum gradually increases. In addition, based on the elasto-photoelectric effect, the refractive index of the optical fiber will change after it is bent, and the amount of change is related to the bending radius of the optical fiber. Therefore, when the optical fiber magnetic field sensor designed by the patent of the present invention is placed in a magnetic field, the magnetic strip is further deformed by the magnetic force that drives the bent optical fiber, resulting in a change in the bending radius, affecting the refractive index of the optical fiber and causing spectral drift. Based on the above findings, the technical solution of the patent of the present invention proposes an optical fiber magnetic field sensor and a magnetic field detection method based on macrobending loss.

[0049] The first aspect of the embodiment of the present application proposes an optical fiber magnetic field sensor 100 based on macrobending loss, please refer to Figure 1 , Figure 1 It is a schematic diagram of an optical fiber magnetic field sensor 100 provided in an embodiment of the present application, wherein the optical fiber magnetic field sensor 100 comprises: an optical fiber 10, a magnetic strip 20, and a fixing member 30, wherein the optical fiber 10 is at least partially bent to form a bent portion, and both ends of the magnetic strip 20 are connected to the bent portion, and both ends of the optical fiber 10 pass through the fixing member 30, and the fixing member 30 is preferably a glass tube, and may also be a cylindrical tube made of metal material, organic material or ceramic material.

[0050] The present invention provides a bending portion in the optical fiber 10, thereby changing the bending radius of the optical fiber 10 and then changing the refractive index of the optical fiber, so as to obtain spectrum data of spectral drift, and then obtain a spectrum for determining the magnitude of the magnetic field by characterizing the wavelength drift in the spectrum, thereby realizing the detection of the magnitude of the magnetic field. Compared with the prior art, the technical solution of the present invention has the advantages of simple preparation, flexible control and high measurement accuracy.

[0051] In an implementation of the first aspect of the present application, the optical fiber 10 includes a core and a cladding, the refractive index N1 of the cladding is, the refractive index N2 of the core is, the refractive index N1 of the cladding is less than the refractive index N2 of the core, specifically, the refractive index N2 of the core is any one of 1.46, 1.47, 1.48, and 1.50, preferably, the refractive index N2 of the core is 1.4682, and the refractive index N1 of the cladding is 1.4628;

[0052] Through the technical solution in this embodiment, the refractive index N1 of the cladding is significantly different from the refractive index N2 of the core, which is conducive to obtaining an easy-to-observe spectral drift diagram, thereby facilitating obtaining a spectral diagram that characterizes the magnetic field size through the wavelength of the optical fiber magnetic field sensor 100.

[0053] In an implementation of the first aspect of the present application, the optical fiber 10 is a quartz single-mode optical fiber, the diameter D1 of the quartz single-mode optical fiber is 125um, and the diameter D2 of the fiber core is 8-10um. Specifically, the diameter D2 of the fiber core is 9um. Through the technical solution in this embodiment, the loss of the light source signal in the optical fiber 10 is reduced, which is conducive to improving the measurement accuracy of the optical fiber magnetic field sensor 100.

[0054] In an implementation of the first aspect of the present application, please refer again to Figure 1 The magnetic strip 20 is a flexible magnetic strip, and both ends of the flexible magnetic strip are connected to the curved portion by ultraviolet glue 40. Through the technical solution in this embodiment, the flexible magnetic strip can be better fixed on the curved portion. The flexible magnetic strip is arranged along the chord length direction corresponding to the curved portion, and the length direction of the flexible magnetic strip is perpendicular to the central axis of the fixing member 30 (glass tube).

[0055] In an implementation of the first aspect of the present application, the length of the flexible magnetic strip is 6mm-10mm, and the side length of the cross-section of the flexible magnetic strip is 0.2mm to 1mm. Preferably, the length of the flexible magnetic strip is 8mm, and the cross-section of the flexible magnetic strip is 0.2mm×0.2mm to 1mmx1mm.

[0056] In an implementation of the first aspect of the present application, the flexible magnetic strip includes magnetic nanoparticles, and the mass proportion of the magnetic nanoparticles is 10%-50%. Figure 8 The flexible magnetic strip is a string-shaped magnetic strip. It should be noted that the preparation process of the flexible magnetic strip is as follows:

[0057] 1) Using laser micromachining to etch strip grooves on a stainless steel plate to form a mold, the groove size is 0.5 mm × 0.5 mm × 40 mm;

[0058] 2) 5 g of polydimethylsiloxane (PDMS) solution was prepared at a mass ratio of 10:1, and then 30% (w / w) of nano-iron tetroxide particles were added, stirred evenly, and then the magnetic solution was evenly filled into the grooves of the mold, and the overflowed magnetic solution was scraped off with a blade so that it was only filled in the groove structure;

[0059] 3) The mold is heated at 120 degrees Celsius for 5 minutes to completely solidify the magnetic solution. After cooling, the solidified flexible magnetic strip 20 is taken out with tweezers.

[0060] Through the technical solution in this embodiment, the magnetic nanoparticles of the flexible magnetic strip have a higher mass ratio, so that the flexible magnetic strip can better sense the magnetic force of the magnetic field to be measured, thereby achieving the improvement of the magnetic field sensing performance, which is beneficial to improving the accuracy of magnetic field detection of the optical fiber magnetic field sensor 100.

[0061] In an implementation of the first aspect of the present application, the bending radius of the bending portion is 8 mm to 13.5 mm. Figure 1 The optical fiber 10 includes a first end 11 and a second end 12, and the first end 11 and the second end 12 penetrate the fixing member 30. The optical fiber magnetic field sensor 100 includes: a bending radius adjuster (not shown in the figure), which is arranged in the fixing member 30. The bending radius adjuster is used to drive the position of the first end 11 or the second end 12 or the part of the optical fiber 10 close to the first end 11 or the part of the optical fiber 10 close to the second end 12 in the fixing member 30, so as to adjust the bending radius of the bending part of the optical fiber 10. The bending radius adjuster includes a gear structure, and the first end 11 or the second end 12 or the part of the optical fiber 10 close to the first end 11 or the part of the optical fiber 10 close to the second end 12 can be driven to extend or retract in the fixing member 30 by rotating the gear structure. Through the technical solution in this embodiment, the bending radius of the optical fiber 10 can be adjusted, so as to facilitate the screening of the bending radius with a more obvious interference effect, which is conducive to improving the accuracy of magnetic field detection of the optical fiber magnetic field sensor 100.

[0062] Please refer to Figure 2 , Figure 2 It is a schematic diagram of the composition structure of the optical fiber magnetic field sensing device provided in an embodiment of the present invention. The second aspect of the present application proposes an optical fiber magnetic field sensing device, including the optical fiber magnetic field sensor described in any one of the above embodiments, and the optical fiber magnetic field sensing device also includes a laser light source and a spectrometer, and the laser light source and the spectrometer are respectively connected to the two ends of the optical fiber.

[0063] The third aspect of the present application provides a method for preparing an optical fiber magnetic field sensor, which is used to prepare an optical fiber sensor as described in any of the above embodiments. Figure 3 and Figure 5 , Figure 3 is a flow chart of a method for preparing an optical fiber magnetic field sensor provided by an embodiment of the present invention, Figure 5 A schematic diagram of an optical fiber magnetic field sensor at different bending radii provided by an embodiment of the present invention, wherein the preparation method comprises the following steps:

[0064] S11: bending at least a portion of the optical fiber to form a bent portion, and adjustably connecting the optical fiber to the fixing member 30;

[0065] S12: connecting a laser light source to one end of the optical fiber of the optical fiber magnetic field sensor, connecting a spectrometer to the other end of the optical fiber, controlling the laser light source to emit laser light to the optical fiber, and the spectrometer to receive the laser light transmitted through the optical fiber;

[0066] S13: By tightening the optical fiber, the bending radius of the bending portion gradually changes within a set range. Specifically, by tightening the optical fiber 10, the bending radius of the bending portion gradually changes within a range of 13.5 mm-8 mm. After tightening the optical fiber 10, the length of the magnetic strip 20 is stretched, such as Figure 5 As shown, before tightening the optical fiber 10, the magnetic strip corresponds to Figure 5 The magnetic strip 20 in the optical fiber 10 corresponds to Figure 5 The magnetic strip 20';

[0067] S14: Acquire a first optical spectrum of different optical fiber bending radii of the optical fiber magnetic field sensor, and determine an optimal bending radius according to a resonance peak in the first optical spectrum.

[0068] The preparation method further comprises: screening lasers with wavelengths of 1480 nm-1540 nm by the spectrometer 300 .

[0069] It should be noted that the interference spectrum formed after the optical fiber 10 is bent will be affected by the string-shaped magnetic strip fixed by the ultraviolet glue 40, as well as the stress change when the ultraviolet glue 40 dripped in the fixing part 30 is cured when fixing the bent shape of the optical fiber 10. Therefore, the final optical fiber magnetic field sensor 100 is bent due to the optical fiber 10, and the spectrum (including the first spectrum and the second spectrum) formed by the laser light source 200 propagating through the optical fiber magnetic field sensor 100 to the spectrometer 300 will be offset.

[0070] like Figure 6 As shown, according to Figure 6 The peak resonance in the optical fiber 10, when the bending radius of the optical fiber 10 is 13.5mm, the first spectrum is a straight line without obvious resonance peaks, wherein when the bending radius is 12mm and 11mm, the resonance peaks begin to appear, but are still not obvious, when the bending radius of the optical fiber magnetic field sensor 100 is gradually adjusted, a significant resonance peak gradually appears, wherein when the bending radius is 10mm and 9.5mm, the first spectrum has obvious resonance peaks, and the resonance peaks of the two are relatively close, wherein when the bending radius is 9mm and 8mm, the first spectrum has very significant resonance peaks, and the resonance peak is most significant when the bending radius is 8mm, so 8mm is the optimal bending radius of the optical fiber magnetic field sensor 100. The magnetic field detection method in the embodiment of the present application dynamically adjusts the bending radius of the bending portion of the optical fiber 10 to obtain the first spectrum at different bending radii and different wavelengths, so as to realize the determination of the optimal bending radius through the resonance peak in the first spectrum, which is conducive to improving the perception performance of the optical fiber magnetic field sensor 100 to the magnetic field to be measured, and is conducive to improving the measurement accuracy of the optical fiber magnetic field sensor 100.

[0071] The preparation method of the optical fiber magnetic field sensor in the embodiment of the present application dynamically adjusts the bending radius of the bending portion of the optical fiber 10 to obtain a first spectrum diagram at different bending radii and different wavelengths, thereby determining the optimal bending radius through the resonant peak in the first spectrum diagram, which is beneficial to improving the sensing performance of the optical fiber magnetic field sensor 100 for the magnetic field to be measured, and is beneficial to improving the measurement accuracy of the optical fiber magnetic field sensor 100.

[0072] The fourth aspect of the present application also proposes a magnetic field detection method, please refer to Figure 4 , Figure 4 A flow chart of a magnetic field detection method provided in an embodiment of the present invention, wherein the magnetic field detection method adopts the optical fiber magnetic field sensor 100 described in any one of the above embodiments, and the magnetic field detection method comprises:

[0073] S21: Acquire a second spectrum of the optical fiber magnetic field sensor 100 in magnetic fields of different intensities;

[0074] S22: Connecting the laser light source 200 to one end of the optical fiber 10 of the optical fiber magnetic field sensor 100, and connecting the spectrometer 300 to the other end of the optical fiber 10;

[0075] S23: placing the optical fiber magnetic field sensor 100 in a magnetic field to be measured, wherein the magnetic field direction of the magnetic field to be measured is parallel to the direction of the flexible magnetic strip.

[0076] S24: controlling the laser light source 200 to emit laser light to the optical fiber 10, and the spectrometer 300 to receive the laser light transmitted through the optical fiber 10, and obtain measurement spectrum information;

[0077] S25: Compare the measured spectrum information with the second spectrum diagram and determine the magnitude of the magnetic field to be measured.

[0078] In an implementation of the fourth aspect of the present application, the magnetic field detection method includes:

[0079] S201: tightening the optical fiber so that the bending radius of the bending portion gradually changes within a range of 13.5 mm to 8 mm;

[0080] S202: screening lasers with wavelengths of 1480 nm to 1540 nm by the spectrometer;

[0081] S203: Obtain a first spectrum graph corresponding to the bending radius and the wavelength under different bending radii.

[0082] In an implementation of the fourth aspect of the present application, please refer to Figure 7 , Figure 7 The second spectrum diagram of the optical fiber magnetic field sensor 100 under different magnetic fields provided by the embodiment of the present invention, wherein obtaining the second spectrum diagram of the optical fiber magnetic field sensor 100 under magnetic fields of different intensities comprises:

[0083] S301: placing the optical fiber magnetic field sensor 100 in a magnetic field with an intensity of 0 mT-20 mT;

[0084] S302: screening lasers with wavelengths of 1420nm-1540nm by the spectrometer 300;

[0085] S303: Obtain a second spectrum diagram for characterizing the corresponding relationship between wavelength and magnetic field intensity.

[0086] Specifically, after determining the optimal bending radius of the optical fiber magnetic field sensor 100, the optical fiber magnetic field sensor 100 is placed in a magnetic field, and the magnetic field strength is gradually increased from 0 mT to 20 mT by changing the size of the magnetic field, thereby obtaining a second spectrum. The magnetic field detection method in the embodiment of the present application obtains a second spectrum for characterizing the correspondence between wavelength and magnetic field strength through the optimal bending radius. Finally, the size of the magnetic field to be measured can be measured by characterizing the wavelength drift in the second spectrum. The magnetic field detection method uses actual magnetic field strength data as calibration data and reference data, thereby improving the measurement accuracy of the magnetic field detection method.

[0087] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or may be indirectly connected to the other element through an intermediate element.

[0088] In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0089] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0090] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0091] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0092] In the embodiments provided in the present application, it should be understood that the disclosed devices / robots and methods can be implemented in other ways. For example, the device / robot embodiments described above are merely schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0093] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0094] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0095] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. An optical fiber magnetic field sensor based on macrobending loss, characterized in that: The optical fiber magnetic field sensor comprises: an optical fiber, wherein the optical fiber is at least partially bent to form a bent portion; A magnetic strip, two ends of which are connected to the bent portion; A fixing member is connected to the optical fiber and keeps the bent portion bent.

2. The optical fiber magnetic field sensor according to claim 1, characterized in that: The optical fiber includes a core and a cladding, and the refractive index N1 of the cladding is smaller than the refractive index N2 of the core.

3. The optical fiber magnetic field sensor according to claim 1, characterized in that: The optical fiber is a quartz single-mode optical fiber, the diameter D1 of the quartz single-mode optical fiber is 125um, and the diameter D2 of the fiber core is 8-10um.

4. The optical fiber magnetic field sensor according to claim 1, characterized in that: The magnetic strip is a flexible magnetic strip, and two ends of the flexible magnetic strip are connected to the curved portion by ultraviolet glue.

5. The optical fiber magnetic field sensor according to claim 4, characterized in that: The length of the flexible magnetic strip is 6mm-10mm, and the side length of the cross section of the magnetic strip is 0.2mm to 1mm.

6. The optical fiber magnetic field sensor according to claim 4, characterized in that: The flexible magnetic strip includes magnetic nanoparticles, and the mass proportion of the magnetic nanoparticles is 10%-50%.

7. The optical fiber magnetic field sensor according to any one of claims 1 to 6, characterized in that: The bending radius of the bending portion is 8mm-13.5mm.

8. An optical fiber magnetic field sensing device, characterized in that: It comprises the optical fiber magnetic field sensor as described in any one of claims 1 to 7, and also comprises a laser light source and a spectrometer, wherein the laser light source and the spectrometer are respectively connected to two ends of the optical fiber.

9. A method for preparing an optical fiber magnetic field sensor, characterized in that: The method for preparing the optical fiber sensor according to any one of claims 1 to 7 comprises the following steps: Bend at least a portion of the optical fiber to form a bent portion, and adjustably connect the optical fiber to the fixing member; Connecting a laser light source to one end of the optical fiber of the optical fiber magnetic field sensor, connecting a spectrometer to the other end of the optical fiber, controlling the laser light source to emit laser light to the optical fiber, and the spectrometer to receive the laser light transmitted through the optical fiber; By tightening the optical fiber, the bending radius of the bending portion gradually changes within a set range; A first optical spectrum diagram of different optical fiber bending radii of the optical fiber magnetic field sensor is obtained, and an optimal bending radius is determined according to a resonance peak in the first optical spectrum diagram.

10. A magnetic field detection method, characterized in that: Using the optical fiber magnetic field sensor according to any one of claims 1 to 7, the magnetic field detection method comprises: Acquire a second spectrum graph of the optical fiber magnetic field sensor in magnetic fields of different intensities; Connecting a laser light source to one end of the optical fiber of the optical fiber magnetic field sensor, and connecting a spectrometer to the other end of the optical fiber; Placing the optical fiber magnetic field sensor in the magnetic field to be measured; Controlling the laser light source to emit laser light to the optical fiber, and the spectrometer to receive the laser light transmitted through the optical fiber to obtain measurement spectrum information; The measured spectrum information is compared with the second spectrum diagram to determine the magnitude of the magnetic field to be measured.

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