An optical fiber geomagnetic sensing probe, system and geomagnetic measurement method

Abstract

The present application discloses an optical fiber geomagnetic sensing probe, a system and a geomagnetic measurement method. The probe includes: a first and a second optical fiber, a first and a second elastic unit, a first, a second and a third magnetostrictive unit; the lengths of the first elastic unit, the second elastic unit and the first magnetostrictive unit are the same; the lengths of the second magnetostrictive unit and the third magnetostrictive unit are both half of the length of the first magnetostrictive unit; the first optical fiber is attached to the first elastic unit, both ends of the first elastic unit are respectively fixed at both ends of the first magnetostrictive unit, and the middle of the first magnetostrictive unit is fixed; the second elastic unit is located between the second magnetostrictive unit and the third magnetostrictive unit, one end of the second magnetostrictive unit and the third magnetostrictive unit abuts against the second elastic unit, and the other ends are respectively fixed; the second optical fiber is attached to the second elastic unit. The probe provided by the present application has strong anti-interference ability and high sensitivity.

Description

Technical Field

[0001] This application belongs to the technical field of fiber optic sensing, and more specifically, relates to an optical fiber geomagnetic sensing probe, a system, and a geomagnetic measurement method. Background Art

[0002] Fiber optic sensing technology has been widely used due to numerous advantages, especially favored in special application fields such as high temperature and high pressure. Fiber optic sensing technology has also been applied to the field of magnetic field measurement. Currently, there are different fiber optic geomagnetic sensors, but there is still room for improvement.

[0003] For example, in the marine earthquake and tsunami monitoring and early warning system, the seabed geomagnetic sensor is an important component. However, the marine environment has large interference and harsh application conditions. Currently, conventional fiber optic geomagnetic sensors have defects such as poor anti-interference ability and low sensitivity, and cannot meet the high-standard geomagnetic detection requirements in marine earthquake and tsunami monitoring, that is, they cannot meet the marine geomagnetic detection requirements.

[0004] As can be seen from the above, there are technical problems in the prior art that the fiber optic geomagnetic sensor has poor anti-interference ability, low sensitivity, and cannot meet the marine geomagnetic detection requirements. Summary of the Invention

[0005] Aiming at the defects of the related technology, this application provides an optical fiber geomagnetic sensing probe, a system, and a geomagnetic measurement method, aiming to solve the problems of poor anti-interference ability, low sensitivity of the fiber optic geomagnetic sensor in the related technology, and the inability to meet the marine geomagnetic detection requirements.

[0006] The technical solution is as follows:

[0007] According to one aspect of this application, an optical fiber geomagnetic sensing probe includes: a first optical fiber, a second optical fiber, a first elastic unit, a second elastic unit, a first magnetostrictive unit, a second magnetostrictive unit, and a third magnetostrictive unit; the length of the first elastic unit is the same as the length of the first magnetostrictive unit; the length of the second elastic unit is the same as the length of the first elastic unit; the lengths of the second magnetostrictive unit and the third magnetostrictive unit are both half of the length of the first magnetostrictive unit; the first optical fiber is attached to the first elastic unit, both ends of the first elastic unit are respectively fixed at both ends of the first magnetostrictive unit, and the middle of the first magnetostrictive unit is fixed; the second elastic unit is located between the second magnetostrictive unit and the third magnetostrictive unit, one end of the second magnetostrictive unit and the third magnetostrictive unit abuts against the second elastic unit, and the other ends are respectively fixed; the second optical fiber is attached to the second elastic unit.

[0008] According to one aspect of the present application, an optical fiber geomagnetic sensing system includes the optical fiber geomagnetic sensing probe, the optical path module, and the phase modulation and demodulation module as described above; the optical path module includes a laser.

[0009] According to one aspect of the present application, a geomagnetic measurement method based on the optical fiber geomagnetic sensing system as described above includes: demodulating the interference signal to obtain phase information; the interference signal is obtained by Michelson interference of two optical signals in the first optical fiber and the second optical fiber of the optical fiber geomagnetic sensing probe in the optical fiber geomagnetic sensing system; using the relationship between the phase information and the geomagnetic quantity to obtain the geomagnetic quantity corresponding to the phase information, so as to achieve geomagnetic measurement.

[0010] According to one aspect of the present application, a geomagnetic measurement device based on the optical fiber geomagnetic sensing system as described above includes: a demodulation module for demodulating the interference signal to obtain phase information; the interference signal is obtained by Michelson interference of two optical signals in the first optical fiber and the second optical fiber of the optical fiber geomagnetic sensing probe in the optical fiber geomagnetic sensing system. A geomagnetic measurement module for using the relationship between the phase information and the geomagnetic quantity to obtain the geomagnetic quantity corresponding to the phase information, so as to achieve geomagnetic measurement.

[0011] According to one aspect of the present application, an electronic device includes: at least one processor, at least one memory, and at least one communication bus. Among them, a computer program is stored on the memory, and the processor reads the computer program in the memory through the communication bus; when the computer program is executed by the processor, the geomagnetic measurement method as described above is implemented.

[0012] According to one aspect of the present application, a storage medium stores a computer program thereon, and when the computer program is executed by a processor, the geomagnetic measurement method as described above is implemented.

[0013] According to one aspect of the present application, a computer program product includes a computer program. The computer program is stored in a storage medium, and a processor of a computer device reads the computer program from the storage medium. The processor executes the computer program, so that when the computer device executes, the geomagnetic measurement method as described above is implemented.

[0014] The present application has the following beneficial effects:

[0015] The fiber optic geomagnetic sensing probe provided by this application, when in a certain magnetic field environment, changes in the external magnetic field will cause the first magnetostrictive material, the second magnetostrictive material, and the third magnetostrictive material to elongate (or shorten), that is, to deform. The deformation of the first magnetostrictive material will drive the deformation of the first elastic material, and then cause the first optical fiber to deform. Similarly, the second optical fiber will also deform. The deformations of the first optical fiber and the second optical fiber cause the optical signal inside the optical fiber to change in phase. Then, by measuring the phase changes of the optical signals in the first optical fiber and the second optical fiber, the external magnetic field can be measured. The length of the first elastic unit of the fiber optic geomagnetic sensing probe provided by this application is the same as the length of the first magnetostrictive unit. The length of the second elastic unit is the same as the length of the first elastic unit. The lengths of the second magnetostrictive unit and the third magnetostrictive unit are both half of the length of the first magnetostrictive unit. As a result, the sum of the deformation amounts of the second magnetostrictive unit and the third magnetostrictive unit is the same as the deformation amount of the first magnetostrictive unit. Then, through the first elastic unit and the second elastic unit, the first optical fiber and the second optical fiber are driven to generate opposite deformations (stretched and compressed respectively), causing the phase change directions of the first optical fiber and the second optical fiber to be opposite, that is, a push-pull type is formed, and the phase change amount of the interferometer will also increase by a factor of two, doubling the sensitivity. In addition, the strong magnetic sensitivity of the magnetostrictive unit and the high elasticity of the elastic unit in the probe also greatly improve the magnetic induction sensitivity of the probe.

[0016] When environmental interference occurs, such as temperature changes, or when the same-source devices are unstable, the directions of the phase changes of the first optical fiber and the second optical fiber of the push-pull type probe are the same and can be cancelled out, that is, it will not cause a change in the interference phase amount of the fiber optic Michelson interference structure, eliminating external interference. The probe provided by this application has a special push-pull type structure, which can fundamentally eliminate the influence of many environmental interferences such as temperature and unstable factors such as the same-source devices, thereby improving the anti-interference ability, and can also double the sensitivity of the probe; and the probe with a push-pull type structure can be perfectly matched with the Michelson interference structure, further improving the sensitivity and accuracy, greatly improving the sensing performance, so that it can be applied to harsh conditions such as the marine environment, solving the technical problems of poor anti-interference ability, low sensitivity, and inability to meet the marine geomagnetic detection requirements in the existing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of a fiber optic geomagnetic sensing probe provided by an embodiment of this application;

[0018] Figure 2 is a schematic physical design diagram of two fiber optic geomagnetic sensing probes provided by an embodiment of this application;

[0019] Figure 3 is a fiber optic geomagnetic sensing system based on the Michelson interference technology provided by an embodiment of this application;

[0020] Figure 4 is a flowchart of a geomagnetic measurement method based on an optical fiber geomagnetic sensing system as shown in Figure 3 ;

[0021] Figure 5 is a structural block diagram of a geomagnetic measurement device based on an optical fiber geomagnetic sensing system as shown in Figure 3 ;

[0022] Figure 6 is a structural block diagram of an electronic device shown according to an exemplary embodiment. Detailed implementation manners

[0023] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0024] Those skilled in the art of the present technology can understand that unless specifically stated otherwise, the singular forms "a", "an", "the" and "said" used herein may also include the plural forms. It should be further understood that the term "including" used in the specification of the present application means the presence of the described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or their groups. It should be understood that when we say that an element is "connected" or "coupled" to another element, it can be directly connected or coupled to other elements, or there may also be intermediate elements. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The phrase "and / or" used herein includes all or any unit and all combinations of one or more of the associated listed items.

[0025] As described above, in the related art, there are technical problems such as poor anti-interference performance, low sensitivity of optical fiber geomagnetic sensors, and inability to meet the requirements of marine geomagnetic detection.

[0026] Geomagnetic sensors are used for geomagnetic quantity measurement. Currently, optical fiber geomagnetic sensors have poor anti-interference performance and low sensitivity. When applied to some special environments, such as the marine environment with large environmental interference and harsh application conditions, their sensing performance cannot meet the actual measurement requirements.

[0027] Please refer to Figure 1 , Figure 1 shows a structural schematic diagram of an optical fiber geomagnetic sensing probe provided by an embodiment of the present application.Figure 1 The fiber optic geomagnetic sensing probe shown in Figure 1 includes: a first optical fiber 101, a second optical fiber 102, a first elastic unit 201, a second elastic unit 202, a first magnetostrictive unit 301, a second magnetostrictive unit 302, and a third magnetostrictive unit 303. S1, S2, and S3 are the fixed points of the first magnetostrictive unit 301, the second magnetostrictive unit 302, and the third magnetostrictive unit 303, respectively.

[0028] Among them, the length of the first elastic unit 201 is the same as that of the first magnetostrictive unit 301; the length of the second elastic unit 202 is the same as that of the first elastic unit 201; the lengths of the second magnetostrictive unit 302 and the third magnetostrictive unit 303 are both half of the length of the first magnetostrictive unit 301.

[0029] The first optical fiber 101 is attached to the first elastic unit 201. Both ends of the first elastic unit 201 are respectively fixed at both ends of the first magnetostrictive unit 301, and the middle of the first magnetostrictive unit 301 is fixed.

[0030] The second elastic unit 202 is located between the second magnetostrictive unit 302 and the third magnetostrictive unit 303. One end of the second magnetostrictive unit 302 and the third magnetostrictive unit 303 abuts against the second elastic unit 202, and the other ends are respectively fixed; the second optical fiber 102 is attached to the second elastic unit.

[0031] When the external magnetic field changes, the length of the first magnetostrictive unit 301 fixed in the middle elongates (or shortens), the length of the first elastic unit 201 elongates (or shortens) accordingly, and the length of the part of the first optical fiber 101 attached to the first elastic unit 201 elongates (or shortens) accordingly; at the same time, the change in the external magnetic field also causes the lengths of the second magnetostrictive unit 302 and the third magnetostrictive unit 303 to elongate (or shorten). Because the non-adjacent ends of the second magnetostrictive unit 302 and the third magnetostrictive unit 303 are fixed, the length of the second elastic unit 202 will shorten (or elongate), and the length of the part of the second optical fiber 102 attached to the second elastic unit 202 shortens (or elongates) accordingly; that is to say, the change in the external magnetic field will cause the length of the first optical fiber 101 to elongate (or shorten), while the length of the second optical fiber 102 shortens (or elongates), and then the optical signals in the first optical fiber 101 and the second optical fiber 102 undergo phase changes in opposite directions. Based on the phase change amount obtained from the interference of the two optical paths, the geomagnetic quantity can be measured.

[0032] It should be noted that since the length of the first elastic unit 201 is the same as that of the first magnetostrictive unit 301, the length of the second elastic unit 202 is the same as that of the first elastic unit 201, and the lengths of the second magnetostrictive unit 302 and the third magnetostrictive unit 303 are both half of the length of the first magnetostrictive unit 301, the sum of the elongation (or shortening) amounts of the lengths of the second magnetostrictive unit 302 and the third magnetostrictive unit 303 is the same as the elongation (or shortening) amount of the length of the first magnetostrictive unit 301. Furthermore, the first optical fiber and the second optical fiber are driven by the first elastic unit and the second elastic unit to generate opposite deformations (stretched and compressed respectively), causing the phase change directions of the first optical fiber and the second optical fiber to be opposite, that is, a push-pull type is formed, and the phase change amount of the interferometer will also increase by a factor of two, doubling the sensitivity.

[0033] Among them, the first magnetostrictive unit 301, the second magnetostrictive unit 302, and the third magnetostrictive unit 303 all adopt magnetostrictive materials. Such materials will deform, elongate or shorten when the magnetic field changes, and are a type of material with the function of converting electromagnetic energy / mechanical energy. Optical fibers have no magnetic sensitivity, that is, they are not affected by magnetic signals, and magnetostrictive units need to be combined so that the external magnetic field can modulate the phase of the optical signal in the optical fiber.

[0034] In a possible implementation, the first magnetostrictive unit 301, the second magnetostrictive unit 302, and the third magnetostrictive unit 303 are all Terfenol-D materials. Terfenol-D materials have excellent low-field magnetostrictive characteristics, which can improve the magnetic sensitivity of the probe.

[0035] The first elastic unit 201 and the second elastic unit 202 both adopt elastic materials, that is, materials with high elasticity and small elastic modulus, and have the characteristic of being easy to deform. It is worth noting that the large elastic modulus of the optical fiber makes it difficult for the optical fiber to deform following the magnetostrictive unit. If the optical fiber is directly attached to the magnetostrictive unit, due to the poor elasticity and difficulty in deformation of the optical fiber, the magnetic sensitivity of the probe will become very low, resulting in poor sensing performance of the geomagnetic sensor. The elastic unit has the characteristics of being easy to deform and high elasticity. Attaching the optical fiber to the elastic unit will greatly reduce the effective elastic modulus of the optical fiber, amplify the deformation, and thus improve the magnetic sensitivity of the probe.

[0036] In a possible implementation, the first elastic unit 201 and the second elastic unit 202 are both carbon fiber materials. Carbon fiber materials have good elasticity, belong to a sensitivity-enhancing medium, and have excellent characteristics such as high tensile strength, high temperature resistance, corrosion resistance, and far better elasticity than optical fibers. They not only adapt to harsh environments, but also have higher sensitivity to deformation signals, have a deformation amplification function, and can improve the magnetic sensitivity of the probe.

[0037] Both the first optical fiber 101 and the second optical fiber 102 adopt ordinary optical fibers, such as quartz optical fibers.

[0038] It should be noted that the phase change directions of the optical signals in the first optical fiber 101 and the second optical fiber 102 are opposite. After demodulation, a larger phase change amount is obtained, increasing the sensitivity.

[0039] Through the above embodiments, by utilizing the magnetostrictive characteristics of the magnetostrictive unit and the easily deformable characteristics of the elastic unit, the magnetic sensitivity of the probe is improved. The push-pull structure of the probe fundamentally eliminates the influence of many environmental interferences such as temperature and unstable factors such as homologous devices, thereby improving the anti-interference ability. It can also double the sensitivity of the probe. Moreover, the probe with a push-pull structure is perfectly compatible with the fiber optic Michelson interferometer structure. The partial optical fibers of the two arms of the Michelson interferometer can be fully utilized as the optical fibers of the fiber optic geomagnetic sensing probe provided in this application, further improving the magnetic sensitivity and accuracy. Based on the fiber optic geomagnetic sensing probe provided in this application, by using the Michelson fiber interference technology to demodulate the phase change caused by the external magnetic change, high-sensitivity monitoring of the geomagnetic change can be achieved, which can be applied to harsh conditions such as the marine environment, solving the technical problems of poor anti-interference ability, low sensitivity, and inability to meet the marine geomagnetic detection requirements in the existing technology.

[0040] Please refer to Figure 2 , Figure 2 Figure (A) in [reference] shows a physical design schematic diagram of a box-type fiber optic geomagnetic sensing probe provided by an embodiment of this application. Figure 2 Figure (B) in [reference] shows a physical design schematic diagram of a rod-type fiber optic geomagnetic sensing probe provided by an embodiment of this application. Figure 2 Both Figure (A) and Figure (B) in [reference] are designed based on the Figure 1 shown fiber optic geomagnetic sensing probe.

[0041] Figure 2 In (A), L is the optical cable, M is the sealing ring, S is the fixing block, 100 is the optical fiber, 200 is the carbon fiber sheet, and 300 is the magnetostrictive rod. Figure 2 In (B), L is the optical cable, S is the fixing block, 100 is the optical fiber, 200 is the carbon fiber sheet, and 300 is the magnetostrictive rod.

[0042] It should be noted that Figure 2 In (A) and (B), the lengths of the two carbon fiber sheets 200 of the probe are different, which is just an example. If the lengths of the two carbon fiber sheets 200 of the probe are the same, the anti-interference ability of the probe can be stronger.

[0043] Please refer to Figure 3, an embodiment of the present application provides an optical fiber geomagnetic sensing system based on Michelson interference technology, which includes an optical path input / output module, a phase modulation and demodulation module, and a push-pull type sensing probe.

[0044] Among them, the optical path input / output module includes a narrow linewidth laser, an isolator, a coupler, and a long-distance transmission armored optical cable; the phase modulation and demodulation module includes a photodetector, a phase demodulation module, a signal acquisition and processing module, and a modulator; the push-pull type sensing probe can be Figure 1 or Figure 2 the optical fiber geomagnetic sensing probe shown, and the first optical fiber and the second optical fiber of the push-pull type sensing probe are part of the two arms of the Michelson interferometer structure.

[0045] In a possible implementation manner, in order to meet the requirements of subsea all-optical fiber applications, the phase modulation and demodulation module outputs modulation signals with frequencies of w c and 2w c to the narrow linewidth laser, so that the output optical frequency of the narrow linewidth laser will change at the same modulation frequency and thus be modulated.

[0046] In a possible implementation manner, the narrow linewidth laser emits continuous laser with a wavelength of 1550 nm and a linewidth of 5 MHz and outputs it to the subsequent components. The subsequent components include an isolator, a coupler, a long-distance transmission armored optical cable, a photodetector, a phase demodulation module, a signal acquisition and processing module, and a push-pull type sensing probe.

[0047] In a possible implementation manner, a Faraday rotator mirror is connected to the optical fiber end to solve the polarization fading problem in the Michelson interferometer and obtain a better interference effect.

[0048] The beam emitted by the narrow linewidth laser enters the push-pull type sensing probe. The change of the external magnetic field causes the elongation and shortening of the optical fiber in the probe, and then a phase change occurs. Based on the modulation and demodulation algorithm, the phase change amount is obtained. According to the relationship between the phase change amount and the external magnetic field, the external magnetic field strength can be known. The modulation and demodulation algorithm can be the differential cross multiplication (DCM) method or the arctangent method.

[0049] According to the characteristics of the selected material and the capabilities of the Michelson fiber interference system, it can be demonstrated that the minimum measurable magnetic field strength of the geomagnetic sensing system involved in the present invention reaches 0.1 nT, and it has the advantages of low noise and high sensitivity. The demonstration process is as follows:

[0050] Since in the Michelson fiber interference system, the minimum distinguishable phase change amount is 10 -6 rad, according to the formula ΔM = 2π / λ×Δl×n, the corresponding minimum distinguishable optical fiber length change amount is about 10 -13m. Taking the magnetostrictive unit as Terfenol-D material as an example, the saturation magnetostriction of Terfenol-D is greater than 1500 ppm, so the maximum deformation of the magnetostrictive unit is 1.5×10 -3 ; the dynamic stretching coefficient of the magnetostrictive unit is 1.7 nm / A, that is, the magnetostriction rate d 33 = dλ / dH = 1.7 nm / A (where λ is the magnetostrictive deformation and H is the magnetic field strength). If the noise equivalent magnetic field strength of the system is required to be that is, the minimum measurable magnetic field strength is 0.1 nT, then the minimum distinguishable deformation of the magnetostrictive unit is (where the magnetic field strength unit 1 A / m = 1.26 μT).

[0051] Through the above embodiments, the push-pull probe and the Michelson interference structure are perfectly matched, and the fiber optic geomagnetic sensing system based on the Michelson interference technology obtained has a clever structure design, excellent performance, greatly enhanced magnetic sensitivity characteristics, small noise equivalent magnetic field strength, large dynamic range, and strong anti-interference ability, and has strong practicability.

[0052] Please refer to Figure 4 , the embodiment of the present application provides a geomagnetic measurement method based on the Figure 3 shown fiber optic geomagnetic sensing system, as Figure 4 shown, this method may include the following steps:

[0053] Step 400, demodulate the interference signal to obtain phase information.

[0054] The interference signal is obtained by Michelson interference of two optical signals in the first optical fiber and the second optical fiber of the push-pull sensing probe in the fiber optic geomagnetic sensing system.

[0055] In a possible implementation manner, step 400 may include the following steps:

[0056] Step 401, mix the interference signal with the same frequency and double frequency of the laser modulation signal respectively, and then filter out the high-frequency part through a low-pass filter respectively to obtain two signals.

[0057] Step 403, perform differential cross multiplication on the two signals, then subtract them, and finally integrate them to obtain phase information.

[0058] In a possible implementation manner, before step 400, the laser is modulated. Specifically, this method may further include: applying a modulation signal to the laser so that the laser outputs a modulated optical signal. Applying a modulation signal to the laser can better meet the requirements of subsea all-fiber applications.

[0059] Step 420: Obtain the geomagnetic quantity corresponding to the phase information by using the relationship between the phase information and the geomagnetic quantity, so as to realize geomagnetic measurement.

[0060] Among them, the relationship between the phase information and the geomagnetic quantity can be determined through the following steps:

[0061] Step 421: According to the physical parameters of the fiber optic geomagnetic sensing system and the Michelson interference principle, deduce the theoretical relationship between the phase information and the geomagnetic quantity.

[0062] The physical parameters of the fiber optic geomagnetic sensing system include the physical parameters of the magnetostrictive unit, elastic unit and optical fiber in the push-pull probe.

[0063] Step 423: Based on the theoretical relationship, set a known geomagnetic quantity, calculate the corresponding phase information through experiments, fit the actual relationship between the phase information and the geomagnetic quantity, and perform calibration.

[0064] Please refer to Figure 5 , in the embodiment of the present application, a geomagnetic measurement device 900 based on a fiber optic geomagnetic sensing system is provided, including but not limited to: a demodulation module 910 and a geomagnetic measurement module 930.

[0065] Among them, the demodulation module 910 is used to demodulate the interference signal to obtain the phase information; the interference signal is obtained by Michelson interference of two optical signals in the first optical fiber and the second optical fiber of the fiber optic geomagnetic sensing probe in the fiber optic geomagnetic sensing system.

[0066] The geomagnetic measurement module 930 is used to obtain the geomagnetic quantity corresponding to the phase information by using the relationship between the phase information and the geomagnetic quantity, so as to realize geomagnetic measurement.

[0067] It should be noted that when the above-mentioned geomagnetic measurement device performs geomagnetic measurement, only the above-mentioned division of each functional module is used for illustration. In actual application, the above functions can be allocated to different functional modules according to needs, that is, the internal structure of the geomagnetic measurement device will be divided into different functional modules to complete all or part of the functions described above.

[0068] In addition, the above-mentioned geomagnetic measurement device and the embodiment of the geomagnetic measurement method provided in the present application belong to the same concept. The specific ways in which each module performs operations have been described in detail in the method embodiment, and will not be repeated here.

[0069] Please refer to Figure 6 , in the embodiment of the present application, an electronic device 4000 is provided, and the electronic device 4000 may include: a desktop computer, a notebook computer, a server, etc.

[0070] In Figure 6In this case, the electronic device 4000 includes at least one processor 4001, at least one communication bus 4002, and at least one memory 4003.

[0071] Among them, the processor 4001 and the memory 4003 are connected, such as being connected through the communication bus 4002. Optionally, the electronic device 4000 may further include a transceiver 4004, and the transceiver 4004 can be used for data interaction between this electronic device and other electronic devices, such as data sending and / or data receiving, etc. It should be noted that in practical applications, the transceiver 4004 is not limited to one, and the structure of the electronic device 4000 does not constitute a limitation to the embodiments of the present application.

[0072] The processor 4001 can be a CPU (Central Processing Unit), a general-purpose processor, a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute various exemplary logic blocks, modules, and circuits described in combination with the disclosure of the present application. The processor 4001 can also be a combination that realizes computing functions, such as a combination including one or more microprocessors, a combination of a DSP and a microprocessor, etc.

[0073] The communication bus 4002 may include a path for transmitting information between the above components. The communication bus 4002 can be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. The communication bus 4002 can be divided into an address bus, a data bus, a control bus, etc. For the sake of representation, Figure 6 only a thick line is used to represent it in the figure, but it does not mean that there is only one bus or one type of bus.

[0074] The memory 4003 can be a ROM (Read Only Memory), or other types of static storage devices that can store static information and instructions, a RAM (Random Access Memory), or other types of dynamic storage devices that can store information and instructions. It can also be an EEPROM (Electrically Erasable Programmable Read Only Memory), a CD-ROM (Compact Disc Read Only Memory), or other optical disc storage, optical disc storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic disk storage media, or other magnetic storage devices, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto.

[0075] A computer program is stored on the memory 4003, and the processor 4001 reads the computer program stored in the memory 4003 through the communication bus 4002.

[0076] When the computer program is executed by the processor 4001, it implements the geomagnetic measurement method based on the fiber optic geomagnetic sensing system in the above embodiments.

[0077] In addition, an embodiment of the present application provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, it implements the geomagnetic measurement method based on the fiber optic geomagnetic sensing system in the above embodiments.

[0078] An embodiment of the present application provides a computer program product. The computer program product includes a computer program that is stored in a storage medium. The processor of the computer device reads the computer program from the storage medium, and the processor executes the computer program, so that the computer device executes the geomagnetic measurement method based on the fiber optic geomagnetic sensing system in the above embodiments.

[0079] Compared with the related art, the present application has the following beneficial effects:

[0080] 1. By utilizing the magnetostrictive characteristics of the magnetostrictive unit and the deformable characteristics of the elastic unit, the magnetic sensitivity of the probe is improved; the push-pull structure of the probe fundamentally eliminates the influence of many environmental interferences such as temperature and unstable factors such as homologous devices, thereby improving the anti-interference ability and doubling the sensitivity of the probe; moreover, the probe with a push-pull structure is perfectly compatible with the fiber optic Michelson interferometer structure, and part of the optical fibers in the two arms of the Michelson interferometer can be fully utilized as the optical fibers of the fiber optic geomagnetic sensor probe to further improve the magnetic sensitivity and accuracy. Based on the fiber optic geomagnetic sensor probe provided by this application, by adopting the Michelson fiber interference technology to demodulate the phase change caused by the external magnetic change, high-sensitivity monitoring of the geomagnetic change can be achieved, which can be applied to harsh conditions such as the marine environment, and solves the technical problems of poor anti-interference ability, low sensitivity and inability to meet the marine geomagnetic detection requirements in the existing technology.

[0081] 2. The push-pull probe and the Michelson interferometer structure are perfectly matched, and the obtained fiber optic geomagnetic sensing system based on the Michelson interference technology has a clever structure design, excellent performance, greatly enhanced magnetic sensitivity characteristics, small noise equivalent magnetic field intensity, large dynamic range and strong anti-interference ability, and has strong practicability.

[0082] It should be understood that although each step in the flowchart of the accompanying drawings is shown in sequence according to the indication of the arrow, these steps are not necessarily executed in the order indicated by the arrow. Unless there is a clear indication in this article, the execution of these steps has no strict order limit and can be executed in other orders. Moreover, at least a part of the steps in the flowchart of the accompanying drawings may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed alternately or alternately with at least a part of other steps or sub-steps or stages of other steps.

[0083] Those skilled in the art can easily understand that the above are only the preferred embodiments of this application and are not used to limit this application. Any modifications, equivalent replacements and improvements made within the spirit and principle of this application should be included in the protection scope of this application.

Claims

1. An optical fiber geomagnetic sensing probe, characterized in that, The probe is of a push-pull structure, including: a first optical fiber, a second optical fiber, a first elastic unit, a second elastic unit, a first magnetostrictive unit, a second magnetostrictive unit, and a third magnetostrictive unit; the length of the first elastic unit is the same as that of the first magnetostrictive unit; the length of the second elastic unit is the same as that of the first elastic unit; the lengths of the second magnetostrictive unit and the third magnetostrictive unit are both half of the length of the first magnetostrictive unit. The first optical fiber is attached to the first elastic unit, and both ends of the first elastic unit are respectively fixed at both ends of the first magnetostrictive unit, and the middle of the first magnetostrictive unit is fixed by a fixing block. The second elastic unit is located between the second magnetostrictive unit and the third magnetostrictive unit. One end of the second magnetostrictive unit and the third magnetostrictive unit respectively abuts against both sides of the second elastic unit, and the other ends are respectively fixed by a fixing block; the second optical fiber is attached to the second elastic unit. The first optical fiber and the second optical fiber are arranged in parallel, the first elastic unit and the second elastic unit are opposite in position, and the expansion and contraction directions of the first magnetostrictive unit, the second magnetostrictive unit, and the third magnetostrictive unit are the same as the arrangement direction of the first optical fiber / second optical fiber. When the first magnetostrictive unit, the second magnetostrictive unit, and the third magnetostrictive unit are affected by the same external magnetic field, the first elastic unit and the second elastic unit generate opposite deformations.

2. The fiber optic geomagnetic sensing probe according to claim 1, wherein, Both the first elastic unit and the second elastic unit are made of carbon fiber material.

3. The fiber optic geomagnetic sensing probe according to claim 1, characterized in that, The first magnetostrictive unit, the second magnetostrictive unit, and the third magnetostrictive unit are all made of Terfenol-D material.

4. An optical fiber geomagnetic sensing system, characterized in that, It includes the fiber optic geomagnetic sensing probe, the optical path module, and the phase modulation and demodulation module as described in any one of claims 1 to 3; the optical path module includes a laser.

5. The fiber optic geomagnetic sensing system according to claim 4, characterized in that, The system is based on the Michelson interferometer structure; the first optical fiber and the second optical fiber are part of the two arms of the Michelson interferometer structure.

6. The fiber optic geomagnetic sensing system according to claim 5, characterized in that, The tails of the first optical fiber and the second optical fiber are both connected to a Faraday rotator mirror.

7. A geomagnetic measurement method based on the fiber optic geomagnetic sensing system according to any one of claims 4 to 6, characterized in that, It includes: Demodulating the interference signal to obtain phase information; the interference signal is obtained by Michelson interference of two optical signals in the first optical fiber and the second optical fiber of the fiber optic geomagnetic sensing probe in the fiber optic geomagnetic sensing system. Using the relationship between the phase information and the geomagnetic quantity to obtain the geomagnetic quantity corresponding to the phase information to achieve geomagnetic measurement.

8. The method according to claim 7, wherein Before demodulating the interference signal to obtain phase information, the method further includes: Applying a modulation signal to the laser so that the laser outputs a modulated optical signal.

9. The method according to claim 8, wherein Demodulating the interference signal to obtain phase information includes: Mixing the interference signal with the same frequency and the second harmonic of the laser modulation signal respectively, and then filtering out the high-frequency part through a low-pass filter respectively to obtain two signals. Differentially cross-multiplying the two signals, then subtracting, and finally integrating to obtain the phase information.

10. The method according to any one of claims 7 to 9, characterized in that, The relationship between the phase information and the geomagnetic quantity is determined through the following steps: Derive the theoretical relationship between the phase information and the geomagnetic quantity according to the physical parameters of the fiber optic geomagnetic sensing system and the Michelson interference principle; Based on the theoretical relationship, set the known geomagnetic quantity, calculate the corresponding phase information through experiments, fit the actual relationship between the phase information and the geomagnetic quantity and perform calibration.

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