Magnetic-optical conversion structure, push-pull type optical fiber magnetic field measurement probe and geomagnetic measurement device

Abstract

The present application relates to magneto-optical conversion structure, push-pull type optical fiber magnetic field measurement probe and geomagnetic measurement device, the first support is sleeved on the magnetostrictive rod, the first support is circumferentially wound with the first sensing optical fiber, the two ends of the magnetostrictive rod and the first support are connected through the first transmission unit.When the magneto-optical conversion structure receives the magnetic field signal, the length of the magnetostrictive rod will change, thereby pulling the first transmission unit, causing the diameter of the first support to change between the first state and the second state, thereby changing the deformation of the first sensing optical fiber wound on the first support, achieving the purpose of converting the external magnetic field signal into an optical signal. Since the first sensing optical fiber is wound on the first support, the diameter of the first support changes slightly, which can make the first sensing optical fiber obtain a larger deformation, which can greatly reduce the length of the interference arm, effectively reducing the influence of environmental noise on the detection of the magnetic field signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optoelectronic measuring devices, in particular to a magneto-optical conversion structure, a push-pull optical fiber magnetic field measuring probe and a geomagnetic measuring device. BACKGROUND

[0002] The geomagnetic field is one of the basic physical fields of the earth, and as an inherent physical property of the earth, it implies rich and important information in the internal and external space of the earth. As an ancient discipline, geomagnetism has wide applications in many fields such as navigation communication, resource exploration, near-earth space and deep earth research, earthquake prediction and prediction, etc., serving the national economy and national defense construction, on the other hand, geomagnetism has important significance for understanding the earth and the human living environment. In the past two decades, with the development of optical information technology, the price of optical information products has gradually decreased, and optical fiber sensing technology has also developed greatly. Compared with the traditional dynamic measurement technology based on electrical quantities, optical fiber sensors have the advantages of high sensitivity, anti-electromagnetic interference, corrosion resistance, light weight, low power consumption, etc.

[0003] In the prior art, a push-pull optical fiber geomagnetic measuring probe, device and method (CN118169770A) is disclosed, which pastes two interference arms on the front and back surfaces of a strain gauge respectively, but the elongation of the interference arm of the strain gauge changes with the magnetostrictive rod is too small, so it is necessary to paste a very long interference arm to amplify the change of the magnetostrictive rod. The too long interference arm will introduce more environmental noise and reduce the system measurement accuracy. SUMMARY

[0004] In order to solve the defect that the too long interference arm will introduce more environmental noise and reduce the system measurement accuracy, the present application proposes a magneto-optical conversion structure.

[0005] The technical scheme adopted by the present application is a magneto-optical conversion structure, which comprises a first support member, the first support member is sleeved on a magnetostrictive rod, a first sensing optical fiber is wound around the circumference of the first support member, the first support member and the two ends of the magnetostrictive rod are connected through a first transmission unit, the first support member has a first state and a second state with different diameters, and when the magnetostrictive rod is stretched and contracted, the first support member changes between the first state and the second state through the first transmission unit.

[0006] Preferably, the first support member is a cylindrical structure composed of a plurality of first mounting blocks distributed around the circumference of the magnetostrictive rod.

[0007] Preferably, the first transmission unit comprises a first connecting member and a first strain gauge with elasticity, one end of the first strain gauge is connected with the first mounting block, the other end extends away from the magnetostrictive rod and is connected with the end of the magnetostrictive rod through the first connecting member.

[0008] Preferably, the plurality of first mounting blocks are identical, the first strain gauge has a plurality of first strain gauges, and the plurality of first strain gauges are uniformly distributed at the same angle along the circumference of the magnetostrictive rod.

[0009] Preferably, the first support member is sleeved at the middle position of the magnetostrictive rod.

[0010] In order to solve the defects that the too long interference arm introduces more environmental noise, the single probe is easily affected by temperature, and the system measurement accuracy is reduced, the application provides a push-pull type optical fiber magnetic field measurement probe.

[0011] The application also discloses a push-pull type optical fiber magnetic field measurement probe, which comprises the above-mentioned magneto-optical conversion structure, and is connected with a contrast module.

[0012] The contrast module comprises a second support member, the second support member is sleeved outside the elastic unit, the second support member is circumferentially wound with a second sensing optical fiber, the second support member and the elastic unit are connected through a second transmission unit at both ends, the second support member has third and fourth states with different diameters, and the elastic unit abuts against the magnetostrictive rod in the axial direction of the magnetostrictive rod.

[0013] When the magnetostrictive rod is elongated / shortened, the elastic unit is shortened / elongated by the same distance, and the second support member is changed between the third state and the fourth state through the second transmission unit.

[0014] Preferably, the elastic unit comprises an elastic gasket and a support rod, and the elastic gasket abuts against the support rod in the axial direction of the support rod.

[0015] The second support member is in a cylindrical structure, and the cylindrical structure is composed of a plurality of second mounting blocks distributed along the circumference of the magnetostrictive rod.

[0016] The second transmission unit comprises a second strain gauge and a second connecting piece, one end of the second strain gauge is connected with the second mounting block, the other end extends away from the support rod and is connected with the end of the support rod through the second connecting piece.

[0017] The elastic gasket is arranged between the second connecting piece and the second support member.

[0018] Preferably, the application further comprises a cylindrical shell, the magneto-optical conversion structure and the contrast module are arranged in the cylindrical shell, the shape of the second connecting piece and the shape of the inner wall of the cylindrical shell are matched with each other, a limiting rod is connected in the cylindrical shell, the second connecting piece is provided with a limiting hole, and the second connecting piece is sleeved outside the limiting rod through the limiting hole.

[0019] Preferably, the first sensing optical fiber and the second sensing optical fiber are the same optical fiber, the first support and the second support are the same in shape and size, the magnetostrictive rod and the elastic unit are the same in length in the initial state, the first support is sleeved on the magnetostrictive rod at a position corresponding to the position at which the second support is sleeved on the elastic unit, the first transmission unit and the second transmission unit are the same in shape and size, the diameter in the first state and the diameter in the third state are the same, and the diameter in the third state and the diameter in the fourth state are the same.

[0020] In order to solve the problem of low measurement accuracy of the existing geomagnetic measurement device, the application provides a geomagnetic measurement device.

[0021] The application further discloses a geomagnetic measurement device comprising the push-pull optical fiber magnetic field measurement probe.

[0022] Compared with the prior art, the application has the following beneficial effects:

[0023] The application discloses a magneto-optical conversion structure, a first support is sleeved outside a magnetostrictive rod, a first sensing optical fiber is wound around the circumference of the first support, and the two ends of the magnetostrictive rod and the first support are connected through a first transmission unit. When the magneto-optical conversion structure receives a magnetic field signal, the length of the magnetostrictive rod changes, thereby pulling the first transmission unit, causing the diameter of the first support to change between a first state and a second state, thereby changing the deformation amount of the first sensing optical fiber wound on the first support, and achieving the purpose of converting an external magnetic field signal into an optical signal. Since the first sensing optical fiber is wound outside the first support, a small change in the diameter of the first support can cause the first sensing optical fiber to have a large deformation amount, which can greatly reduce the length of the interference arm and effectively reduce the influence of environmental noise on the detection of the magnetic field signal.

[0024] Compared with the prior art, the magneto-optical conversion structure disclosed by the application can reduce the influence of environmental noise on the detection result.

[0025] This application discloses a push-pull fiber optic magnetic field measurement probe. Based on a magneto-optical conversion structure, a control module is connected. The control module includes a second support member fitted onto an elastic unit. A second sensing fiber is circumferentially wound around the second support member. The two ends of the elastic unit and the second support member are connected via a second transmission unit. When the push-pull fiber optic magnetic field measurement probe receives a magnetic field signal, the length of the magnetostrictive rod changes, causing the elastic unit to undergo a length change in opposite direction but at the same distance. This pulls the second transmission unit, causing the diameter of the second support member to change between a third and a fourth state, thereby altering the deformation of the second sensing fiber wound around the second support member. This allows for the separate acquisition of the deformation of the first and second sensing fibers, and calculations can eliminate the influence of temperature on the test results.

[0026] Compared with existing technologies, the push-pull fiber optic magnetic field measurement probe disclosed in this application can avoid the influence of temperature on the detection results.

[0027] This application discloses a geomagnetic measurement device, comprising three push-pull fiber optic magnetic field measurement probes arranged in pairs perpendicularly, thereby enabling the measurement of magnetic fields in different directions.

[0028] Compared with the prior art, the geomagnetic measuring device disclosed in this application can improve the measurement accuracy of the system. Attached Figure Description

[0029] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, wherein:

[0030] Figure 1 A schematic diagram of the structure of a geomagnetic measuring device provided according to an embodiment of the present invention is shown;

[0031] Figure 2 A diagram showing the relationship between geomagnetic elements is provided.

[0032] Figure 3 A schematic diagram of a push-pull fiber optic magnetic field measurement probe according to an embodiment of the present invention is shown.

[0033] Figure 4 It shows that according to Figure 3 A cross-sectional view of a push-pull fiber optic magnetic field measurement probe is provided.

[0034] Figure 5 It shows that according to Figure 3 A schematic diagram of the structure of the second support component in a push-pull fiber optic magnetic field measurement probe is provided.

[0035] Figure 6 It shows that according to Figure 3A structure diagram of a first support or a second support in a push-pull optical fiber magnetic field measurement probe is provided.

[0036] Figure 7 A structure diagram of a base in a geomagnetic measurement device is shown according to Figure 1 A structure diagram of a base in a geomagnetic measurement device is provided.

[0037] Figure 8 A structure diagram of a base in a geomagnetic measurement device is shown according to Figure 1 A connection diagram between a fiber interferometer in a geomagnetic measurement device is provided.

[0038] Label description:

[0039] 1, 1X2 coupler; 2, mirror; 31, first strain gauge; 32, second strain gauge; 41, first support; 42, second support; 51, first sensing optical fiber; 52, second sensing optical fiber; 6, support rod; 7, magnetostrictive rod; 8, limiting rod; 91, first connecting piece; 92, second connecting piece; 10, cylindrical shell; 11, elastic gasket; 12, base; 13, shell; 14, ground joint; 15, multi-core optical cable; 16, mounting groove; 17, fiber interferometer. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings. The examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar parts or parts having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application, and cannot be explained as a limitation to the present application.

[0041] The present application discloses a magneto-optical conversion structure, comprising a first support 41, the first support 41 is sleeved on the magnetostrictive rod, the first support 41 is circumferentially wound with a first sensing optical fiber 51, both ends of the first support 41 and the magnetostrictive rod are connected through a first transmission unit, the first support 41 has a first state and a second state with different diameters, when the magnetostrictive rod is stretched and contracted, the first support 41 is changed between the first state and the second state through the first transmission unit.

[0042] The first support 41 is sleeved outside the magnetostrictive rod, the first sensing optical fiber 51 is wound in the circumferential direction of the first support 41, and the two ends of the magnetostrictive rod and the first support 41 are connected through the first transmission unit. When the magneto-optical conversion structure receives a magnetic field signal, the length of the magnetostrictive rod changes, thereby pulling the first transmission unit, causing the diameter of the first support 41 to change between the first state and the second state, thereby changing the deformation amount of the first sensing optical fiber 51 wound on the first support 41, and achieving the purpose of converting the external magnetic field signal into an optical signal. Since the first sensing optical fiber 51 is wound outside the first support 41, a small change in the diameter of the first support 41 can cause the first sensing optical fiber 51 to have a large deformation amount, which can greatly reduce the length of the interference arm and effectively reduce the influence of environmental noise on the detection of the magnetic field signal. Compared with the prior art, the magneto-optical conversion structure disclosed in the application can reduce the influence of environmental noise on the detection result.

[0043] Specifically, the reason why the first transmission unit is arranged at both ends of the first support 41 is to prevent the deformation of the first sensing optical fiber 51 from changing sharply when the first support 41 is pulled on one side, and even to prevent the first sensing optical fiber 51 from being unable to normally transmit light in the case of severe pulling. Simultaneous pulling through the first transmission unit arranged at both ends can solve this problem. At the same time, the signal amplification multiple when pulling on one side is smaller than the amplification multiple when pulling on both sides, so pulling on both sides is more conducive to improving the quality of signal transmission.

[0044] It should be noted that the end of the magnetostrictive rod refers to a region of the magnetostrictive rod located at the edge of both ends, and does not only refer to the most edge position. In addition, the first support 41 has a first state and a second state with different cross-sectional areas, which means that the area of the same cross-section of the first support 41 changes in the first state and the second state, thereby causing the first sensing optical fiber 51 wound on the first support 41 to deform. The axial direction of the first support 41 refers to the sleeving direction of the magnetostrictive rod, and the circumferential direction of the first support 41 refers to the direction around the axis of the first support 41. At this time, the first sensing optical fiber 51 can be completely wound on the surface of the first support 41, that is, tightly attached to the circumferential surface of the first support 41, or the first sensing optical fiber 51 can not be completely wound on the surface of the first support 41, that is, part of the first sensing optical fiber 51 is not attached to the circumferential surface of the first support 41.

[0045] The change between the first state and the second state of the first support 41 is caused by the length change of the magnetostrictive rod under the action of the magnetic field. After the magnetostrictive rod is elongated, the first transmission unit at both ends pulls the first support 41, so that the cross-sectional area of the first support 41 changes. The first support 41 can be selected as an elastic structure such as a rubber block that can cause the cross-sectional area to change after being compressed. Alternatively, the first support 41 can be selected as a cylindrical structure into which the first transmission unit can be inserted and pulled out. When the first transmission unit is inserted into the cylindrical structure, the cross-sectional area of the cylindrical structure increases.

[0046] It should be explained that the first support 41 is bonded or interference-fitted with the magnetostrictive rod, so that the first support 41 is more stable when changing between the first state and the second state, avoiding complete dependence on the connection of the first transmission unit. In other embodiments, the first support 41 can be suspended outside the magnetostrictive rod and kept in a suspended state by the first transmission unit.

[0047] The magnetostrictive rod 7 is mainly used to connect the carbon fiber first support 41. The carbon fiber first support 41 is bonded with glue, and the size of the geomagnetic field is converted into the size of the length of the magnetostrictive rod 7. The distance between the carbon fiber first support 41 changes with the expansion and contraction of the magnetostrictive rod 7. The specific connection diagram is as follows: Figure 1 、 Figure 3 、 Figure 4 The material of the magnetostrictive rod 7 of the present application is terbium-dysprosium-iron alloy, which has a saturation magnetostrictive coefficient greater than 1500ppm, and the specific size is a cylinder with a diameter of 1cm and a length of 18cm.

[0048] In some embodiments, the first support 41 is cylindrical. Since the optical fiber has a bending radius, the cylindrical structure is selected to minimize the bending radius of the optical fiber and ensure the transmission loss. On the other hand, the cylindrical first support 41 can be wound more turns under the same length of optical fiber, achieving a larger magnification.

[0049] In some embodiments, the first support 41 is a cylindrical structure composed of a plurality of first mounting blocks distributed circumferentially around the magnetostrictive rod.

[0050] Specifically, the first support 41 is a cylindrical structure, which can be a cylinder, a square cylinder, a polygonal cylinder, etc. A plurality of first mounting blocks are distributed circumferentially around the magnetostrictive rod to form a cylindrical structure. The first mounting blocks can move away from the magnetostrictive rod under the drive of the first transmission unit, achieving the purpose of changing the cross-sectional area of the cylindrical structure.

[0051] The shapes of the first mounting blocks can be the same or different, and the sizes of the first mounting blocks can be the same or different. Preferably, the shapes and sizes of the first mounting blocks are the same, so that the position of the first transmission unit can be easily selected and determined, and the cylindrical structure can be uniformly controlled.

[0052] In some specific embodiments, the first transmission unit comprises the first connecting member 91 and the first strain gauge 31 having elasticity, one end of the first strain gauge 31 is connected to the first mounting block, and the other end extends away from the magnetostrictive rod and is connected to the end of the magnetostrictive rod through the first connecting member 91.

[0053] Specifically, the first transmission unit comprises the first strain gauge 31 and the first connecting member 91, the first connecting member 91 is connected to the end of the magnetostrictive rod, one end of the first strain gauge 31 is connected to the first mounting block, and the other end extends away from the magnetostrictive rod and is connected to the first connecting member 91. The first strain gauge 31 can be strained, and when the magnetostrictive rod is elongated, the first strain gauge 31 can generate greater tensile stress, the tensile stress generated by the first strain gauge 31 has a component perpendicular to the axis direction of the first support member 41 and a component parallel to the axis direction of the first support member 41, wherein the component perpendicular to the axis direction of the first support member 41 can cause the first mounting block to move away from the magnetostrictive rod. When the magnetostrictive rod is shortened, the tensile stress on the first mounting block decreases, resulting in a decrease in the component perpendicular to the axis direction of the first support member 41. In addition, since the first strain gauges 31 are arranged on both sides of the first support member 41 in the axis direction of the first support member 41, when the tensile stresses of the first strain gauges 31 on both sides are the same, the component parallel to the axis direction of the first support member 41 on the first strain gauge 31 will be cancelled out, so that the first mounting block can only move away from or close to the magnetostrictive rod.

[0054] By using the first strain gauge 31 capable of being deformed as a transmission component, the controllable performance of the magneto-optical conversion structure is higher, and the magneto-optical conversion structure has smaller size, lighter weight, and simpler structure, which can meet the needs of miniaturization of the magneto-optical conversion.

[0055] In some more specific embodiments, the first mounting blocks are the same, and the first strain gauge 31 has a plurality of first strain gauges 31, and the plurality of first strain gauges 31 are uniformly distributed at the same angle along the circumference of the magnetostrictive rod.

[0056] The plurality of first installation blocks are identical, the plurality of first strain gauges 31 are uniformly distributed at the same angle along the circumference of the magnetostrictive rod, and the posture of the first support 41 as a whole will not tilt due to different tensile stresses, thereby improving the accuracy of the magnetic field measurement result, and meanwhile, the additional calculation amount caused by uneven tension can be reduced.

[0057] In some embodiments, the first support 41 is sleeved at the middle position of the magnetostrictive rod.

[0058] It should be noted that the first support 41 is sleeved at the middle position of the magnetostrictive rod, and the distance between the first support 41 and the two ends of the magnetostrictive rod is equal, which is more conducive to maintaining the stability of the first support 41, thereby obtaining more accurate magnetic field measurement results.

[0059] The application further discloses a push-pull type optical fiber magnetic field measurement probe comprising the above-mentioned magneto-optical conversion structure, and the magneto-optical conversion structure is connected with a contrast module.

[0060] The contrast module comprises a second support 42, the second support 42 is sleeved on the elastic unit, the second support 42 is wound with a second sensing optical fiber 52 in the circumferential direction, and the two ends of the second support 42 and the elastic unit are connected through a second transmission unit.

[0061] When the magnetostrictive rod is elongated / shortened, the elastic unit is shortened / elongated by the same distance, and the second support 42 is changed between the third state and the fourth state through the second transmission unit.

[0062] On the basis of the magneto-optical conversion structure, the contrast module is connected, the contrast module comprises a second support 42, the second support 42 is sleeved on the elastic unit, the second support 42 is wound with a second sensing optical fiber 52 in the circumferential direction, and the two ends of the elastic unit and the second support 42 are connected through a second transmission unit. When the push-pull type optical fiber magnetic field measurement probe receives a magnetic field signal, the length of the magnetostrictive rod changes, causing the elastic unit to change in length in the opposite direction by the same distance, thereby pulling the second transmission unit, causing the diameter of the second support 42 to change between the third state and the fourth state, and further changing the deformation amount of the second sensing optical fiber 52 wound on the second support 42. In this way, the deformation amount of the first sensing optical fiber 51 and the deformation amount of the second sensing optical fiber 52 can be obtained respectively, and the influence of temperature on the test result can be eliminated after calculation. Compared with the prior art, the push-pull type optical fiber magnetic field measurement probe disclosed in the application can avoid the influence of temperature on the detection result.

[0063] Specifically, the setting of the contrast module is to avoid the influence of environmental factors such as temperature on the detection result, so as to obtain more accurate detection result, and avoid the interference of the long loading arm, so as to obtain the push-pull type optical fiber magnetic field measurement probe with higher precision as a whole. In addition, the push-pull type optical fiber magnetic field measurement probe can also double the change amount of the optical fiber, because the push amount and the pressure amount are the same.

[0064] It should be explained that, for the convenience of description, the support appearing in the present application, including the first support 41 and the second support 42, the rest of the structure is similar, for example, only the strain gauge is mentioned, the strain gauge includes the first strain gauge 31 and the second strain gauge 32.

[0065] The support is mainly used for connecting the strain gauge and the sensing optical fiber, the support is adhered in the middle of the strain gauge by using glue, when the connecting piece drives the strain gauge to deform, the support will move inwards or outwards to change the diameter of the circle of the sensing optical fiber on the support, the actual picture of the support is as shown in Figure 6 , the specific connection diagram is as shown in Figure 1 、 Figure 3 、 Figure 4 The support of the present application is 8 similar trapezoidal mounting blocks, after combination, the outer diameter part of the sensing optical fiber is 3cm, the inner diameter is 1.5cm, and the thickness is 4cm.

[0066] The strain gauge is mainly used for connecting the support and the connecting piece, the connection between the strain gauge and the connecting piece and the support is firmly adhered by using glue, when the distance between the two connecting pieces connected with the strain gauge changes, the strain gauge will drive the support to move, so as to change the diameter of the winding circle of the sensing optical fiber on the support, and play the role of amplifying the deformation amount, the specific connection diagram is as shown in Figure 1 、 Figure 3 、 Figure 4 The strain gauge of the present application uses a carbon fiber sheet with a width of 6mm, a length of 23cm and a thickness of 0.25mm.

[0067] The connecting piece is mainly used for connecting the strain gauge, the magnetostrictive rod 7, the support rod 6, the elastic gasket 11 and the cylindrical shell 10, and the connecting piece is the main force support; the material of the connecting piece is preferably a non-magnetic material with a relative magnetic permeability close to 1, so as to ensure that the geomagnetic field completely acts on the magnetostrictive rod 7, otherwise an interference parameter needs to be introduced, the actual picture of the connecting piece is as shown in Figure 5 , the specific connection diagram is as shown in Figure 1 、 Figure 3 、 Figure 4 The connecting piece of the present application uses a carbon fiber plate with a diameter of 20cm and a thickness of 1cm.

[0068] In some embodiments, the elastic unit comprises the elastic gasket 11 and the support rod 6, and the elastic gasket 11 abuts against the support rod 6 in the axial direction of the support rod 6;

[0069] The second support 42 is in a cylindrical structure, which is composed of a plurality of second mounting blocks distributed circumferentially along the magnetostrictive rod;

[0070] The second transmission unit comprises the second strain gauge 32 and the second connecting piece 92, one end of the second strain gauge 32 is connected with the second mounting block, the other end extends away from the support rod 6 and is connected with the end of the support rod 6 through the second connecting piece 92;

[0071] The elastic gasket 11 is arranged between the second connecting piece 92 and the second support 42.

[0072] Specifically, the elastic unit comprises the elastic gasket 11 and the support rod 6, and the elastic gasket 11 can be elastically deformed, and is shortened or thinned when the magnetostrictive rod is elongated, and can be elongated or thickened when the magnetostrictive rod is shortened. Only the deformation of the elastic gasket 11 causes the same size and opposite direction movement between the collation module and the magneto-optical conversion structure, and the collation process has higher coordination, so that the collation module has higher stability and controllability.

[0073] The support rod 6 is mainly used for connecting the elastic gasket 11 and the connecting piece, and supports the two connecting pieces, and the two connecting pieces also have a certain displacement amount, and when the magnetostrictive rod 7 is elongated or shortened, the connecting pieces on both sides of the support rod 6 also realize opposite displacement, and the specific connection diagram is as shown in Figure 1 、 Figure 3 、 Figure 4 The support rod 6 of the present application uses a solid rod of carbon fiber material with a diameter of 1 cm and a length of 18 cm.

[0074] The elastic gasket 11 is mainly used for connecting the support rod 6 and the connecting piece, and when the connecting piece is pressed by the magnetostrictive rod 7, the connecting piece moves to press the elastic gasket 11, so that the spacing between the connecting pieces on both sides of the support rod 6 changes, and then affects the elongation or shortening state of the optical fiber wound on the support, and the specific connection diagram is as shown in Figure 1 、 Figure 3 、 Figure 4 The elastic gasket 11 of the present application uses a silica gel gasket with a diameter of 8 mm and a thickness of 2 mm.

[0075] In other embodiments, the elastic unit is an elastic rod, and by using the elastic rod, the structure of the collation module can be simplified, and the elastic rod itself can be shortened / elongated when the magnetostrictive rod is elongated / shortened, which is a more convenient installation and maintenance implementation.

[0076] The second support 42 is a cylindrical structure, which can be a cylinder, a square cylinder, a polygonal cylinder, etc. The plurality of second mounting blocks are distributed around the circumference of the magnetostrictive rod to form a cylindrical structure. The second mounting blocks can move away from the magnetostrictive rod under the drive of the second transmission unit, so as to change the cross-sectional area of the cylindrical structure.

[0077] The shapes of the plurality of second mounting blocks can be the same or different, and the sizes thereof can be the same or different. Preferably, the shapes and sizes of the plurality of second mounting blocks are the same, so as to facilitate the selection and determination of the position of the second transmission unit, and to uniformly control the cylindrical structure.

[0078] It should be noted that the elastic gasket 11 is arranged between the second connecting piece 92 and the second support 42, so that the deformation of the elastic gasket 11 can be transmitted to the second strain gauge 32, thereby enabling the second sensing optical fiber 52 to normally deform.

[0079] In some embodiments, the second connecting piece 92 has a groove, and the elastic gasket 11 is placed in the groove. The use of the groove and the gasket can greatly reduce the deformation other than the axial direction.

[0080] In some embodiments, the first connecting piece 91 and the second connecting piece 92 between the first support 41 and the second support 42 are the same structure, so that the first connecting piece 91 and the second connecting piece 92 do not need to be arranged respectively, thereby optimizing the structure of the push-pull type optical fiber magnetic field measurement probe, making the layout more compact, and being suitable for application in more miniaturized places.

[0081] In some embodiments, the middle part of each of the two sides of the first support 41 and / or the second support 42 is recessed inward. By recessing inward, the swing length of the first strain gauge 31 and / or the second strain gauge 32 is longer, and in the case of the same size, the amplification factor of the structure can be increased.

[0082] In some embodiments, the first support 41 and the second support 42 are preferably made of a material with low thermal expansion coefficient and high strength, and do not affect the magnetic field, such as carbon fiber material or plastic steel material, so as to reduce the influence of temperature on the sensing optical fiber.

[0083] In some specific embodiments, a cylindrical shell 10 is further included, the magneto-optical conversion structure and the contrast module are arranged in the cylindrical shell 10, the shape of the second connecting piece 92 matches the shape of the inner wall of the cylindrical shell 10, the cylindrical shell 10 is connected with a limiting rod 8, the second connecting piece 92 has a limiting hole, and the second connecting piece 92 is sleeved outside the limiting rod 8 through the limiting hole.

[0084] It should be noted that in order to make the magneto-optical conversion structure and the control module obtain a good control relationship, both can move in the same direction, and avoid the interference caused by the detection result due to the different directions. Therefore, by the setting of the cylindrical shell 10, the magneto-optical conversion structure and the control module are arranged in the cylindrical shell 10, and the limiting rod 8 is connected with the second connecting piece 92 and the cylindrical shell 10 respectively. On the one hand, the inner wall of the cylindrical shell 10 limits the second connecting piece 92, and on the other hand, the limiting rod 8 also limits the second connecting piece 92, so that the control module obtains better control precision under the multiple limiting actions.

[0085] The limiting rod 8 is mainly used for connecting the connecting piece and the cylindrical shell 10 to connect the two structures of push and pull, and the two connecting pieces outside the two groups of structures are fixed in distance by the cylindrical shell 10, and the two connecting pieces in the middle can be moved. The specific connection diagram is as follows Figure 1 、 Figure 3 、 Figure 4 The limiting rod 8 of the present application uses a solid rod of carbon fiber material with a diameter of 1cm and a length of 40cm.

[0086] The cylindrical shell 10 is mainly used for connecting the connecting piece, and forms a relatively closed space with the connecting pieces on both sides to protect the sensitive force device of the push-pull type fiber optic magnetic field measurement probe. The material of the cylindrical shell 10 is preferably a non-magnetic material with a relative magnetic permeability close to 1, which ensures that the geomagnetic field completely acts on the magnetostrictive rod 7, otherwise the interference parameter needs to be introduced. The specific connection diagram is as follows Figure 1 、 Figure 3 、 Figure 4 The cylindrical shell 10 of the present application uses a carbon fiber cylinder with an outer diameter of 21cm, an inner diameter of 20cm and a length of 40cm.

[0087] Both ends of the cylindrical shell 10 have mounting grooves 16, which are mainly used for connecting the limiting rod 8 and the connecting piece. The limiting rod 8 and the mounting groove 16 are bonded by using glue, so that the two ends of the limiting rod 8 can clamp the connecting piece, and at the same time, a certain pre-stress is applied to the connecting piece. The specific connection diagram is as follows Figure 1 、 Figure 3 、 Figure 4 The mounting groove 16 used in the present application is a carbon fiber cylinder with an outer diameter of 1.5cm, an inner diameter of 1cm and a length of 1cm.

[0088] In some more specific embodiments, the shape of the first connecting piece 91 and the inner wall and shape of the cylindrical shell 10 match each other, the first connecting piece 91 also has a limiting hole, and the first connecting piece 91 is sleeved outside the limiting rod 8 through the limiting hole. On the one hand, the inner wall of the cylindrical shell 10 limits the first connecting piece 91, and on the other hand, the limiting rod 8 also limits the first connecting piece 91, so that the magneto-optical conversion structure can be elongated or shortened in a defined direction under the multiple limiting actions, and can be better matched with the contrast module for use.

[0089] In some embodiments, the first sensing optical fiber 51 and the second sensing optical fiber 52 are the same optical fiber, the first support 41 and the second support 42 have the same shape and size, the magnetostrictive rod and the elastic unit have the same length in the initial state, the position of the first support 41 sleeved on the magnetostrictive rod corresponds to the position of the second support 42 sleeved on the elastic unit, the first transmission unit and the second transmission unit have the same shape and size, the diameter in the first state and the diameter in the third state are the same, and the diameter in the third state and the diameter in the fourth state are the same.

[0090] It should be noted that in order to obtain more direct contrast results and avoid excessive calculation, the above parameters of the contrast module and the magneto-optical conversion structure are set to be the same. In addition, the first sensing optical fiber 51 and the second sensing optical fiber 52 are the same optical fiber, which can avoid occupying too many interfaces of the interference analyzer, and also avoid the difference between different optical fibers, thereby achieving more convenient and more accurate detection results.

[0091] In some embodiments, the first sensing optical fiber 51 and the second sensing optical fiber 52 are the same optical fiber, and the tail end of the optical fiber has a mirror 2. Through the setting of the mirror 2, the reflected light returns along the original path, which can double the optical path change, thereby obtaining better detection results. The mirror 2 is mainly used to connect the sensing optical fiber and reflect the sensing optical signal in the sensing optical fiber back, and the specific optical connection is as follows Figure 1 、 Figure 3 The reflectivity of the mirror 2 of the present application is 99.9%, and the specific size is a cylinder with a diameter of 3mm and a length of 1.5cm.

[0092] The application further discloses a geomagnetic measurement device, which comprises the push-pull type optical fiber magnetic field measurement probe.

[0093] The push-pull type optical fiber magnetic field measurement probe comprises three push-pull type optical fiber magnetic field measurement probes which are perpendicular to each other, so that the measurement of the magnetic field in different directions is realized. Compared with the prior art, the geomagnetic measurement device can improve the measurement accuracy of the system.

[0094] The geomagnetic measurement device further comprises a 1X2 coupler 1, which is mainly used for connecting the sensing optical fiber and the optical cable to split the sensing optical signal to two interference arms and combine the reflected optical signal to generate an interference signal for the fiber optic interferometer 17 to demodulate, and the specific optical path connection diagram is as shown in Figure 1 、 Figure 3 and Figure 8 The splitting ratio of the 1X2 coupler 1 of the present application is 50:50, and the specific size is a cylinder with a diameter of 3mm and a length of 6cm.

[0095] The sensing optical fiber is mainly used for connecting the 1X2 coupler 1, the mirror 2 and the support, and the sensing optical fiber is respectively two interference arms of the Michelson interferometer, and the two ends of the sensing optical fiber are glued to the support to have a certain pre-stress and are wound on the support, and the specific connection diagram is as shown in Figure 1 、 Figure 3 The sensing optical fiber of the present application uses the bend-resistant optical fiber of Corning, and the minimum bending diameter is 3cm.

[0096] The geomagnetic measurement device further comprises a base 12, which is used for fixing the three push-pull type optical fiber magnetic field measurement probes, and the base 12 is mainly used for connecting the push-pull type optical fiber magnetic field measurement probes, the 1X2 coupler 1, the mirror 2 and the shell 13, so that the three push-pull type optical fiber magnetic field measurement probes are fixed in a state of being perpendicular to each other, and the 1X2 coupler 1 and the mirror 2 also need to be fixed firmly on the base 12 to prevent the optical device from loosening and affecting the measurement result, and the shell 13 is fixed on the base 12 by screws, and the actual object diagram of the base 12 is as shown in Figure 7 , and the specific connection diagram is as shown in Figure 1 、 Figure 3 、 Figure 4 The material of the base 12 must use a non-magnetic material with a relative magnetic permeability close to 1 to ensure that the geomagnetic field completely acts on the magnetostrictive rod 7, and the present application uses a plastic steel material with a length of 60cm, a width of 60cm and a height of 25cm, and the three holes perpendicular to each other on the base 12 are 21cm in diameter and 5cm in depth, and the push-pull type optical fiber magnetic field measurement probes can be directly put in and fixed.

[0097] The three push-pull type optical fiber magnetic field measurement probes further have a shell 13 outside, which is mainly used for connecting the base 12 and the gland joint 14 to isolate the three push-pull type optical fiber magnetic field measurement probes from the external space and ensure the stability of the magnetic field measurement environment, and the material of the shell 13 is preferably a non-magnetic material with a relative magnetic permeability close to 1 to ensure that the geomagnetic field completely acts on the magnetostrictive rod 7, otherwise an interference parameter needs to be introduced, and the specific connection diagram is as shown in Figure 1 The shell 13 of the present application uses a plastic steel material with an outer size of 60cm in length, 60cm in width, 60cm in height and 2mm in thickness.

[0098] The ferrule 14 is mainly used for connecting the multi-core optical cable 15 and the shell 13, so that the optical fiber in the multi-core optical cable 15 enters the inside of the geomagnetic detection device in a sealed manner and is connected to the 1X2 coupler 1, and the specific connection diagram is as shown in Figure 1 The material of the ferrule 14 of the present application is full PVC plastic, the thread specification of the ferrule 14 is M20x1.5, the opening size is 12mm, and the length is 22.7mm.

[0099] The multi-core optical cable 15 is mainly used for connecting the ferrule 14 and the optical fiber interferometer 17, so that the optical signal between the optical fiber interferometer 17 and the geomagnetic detection device can be stably transmitted, and the specific connection diagram is as shown in Figure 1 、 Figure 8 The diameter of the multi-core optical cable 15 of the present application is 8mm, and three single-mode optical fibers are arranged inside, which meets the ITU-T G.652 standard.

[0100] The optical fiber interferometer 17 is mainly used for connecting the multi-core optical cable, outputting the sensing optical signal to the inside of the geomagnetic detection device through the multi-core optical cable, demodulating the reflected optical interference signal in terms of phase difference, and calculating the geomagnetic seven elements through a related formula to realize the geomagnetic measurement, and the specific connection diagram is as shown in Figure 8 The minimum recognizable phase change amount of the optical fiber interferometer of the present application is 1X10 -5 rad, the sensitivity is greater than 50dB, and the size of the case is 45cm long, 43cm wide and 18cm high.

[0101] The geomagnetic detection device is further described below. The geomagnetic measurement device is used for measuring the horizontal component (H), the north component (X), the east component (Y), the vertical component (Z), the magnetic declination angle (D), the magnetic inclination angle (I) and the total field strength (F) of the geomagnetic field. It is mainly applied to the measurement of the geomagnetic field, the detection of mineral resources, the exploration of engineering and environment, the detection of underground buried objects and the high-precision measurement of the magnetic properties of matter.

[0102] The geomagnetic field is a vector field, which has both size and direction, and is generally represented by a vector F (Jerzy Jankowski, 1999). The description of F is generally expressed by its components, which are called geomagnetic elements. The geomagnetic elements mainly include the horizontal component (H), the north component (X), the east component (Y), the vertical component (Z), the magnetic declination angle (D), the magnetic inclination angle (I) and the total field strength (F), and the relationship between the components is shown in Figure 2 X, Y and Z are commonly used in theoretical research, H, Z and D are commonly used in geomagnetic relative recording, and F, D and I are commonly used in absolute observation. F, H, X, Y and Z are called intensity components, and D and I are called angle components. The relationship between the components is as follows:

[0103] Z=FsinI......................(1-1)

[0104] Y = H sin D (1-2)

[0105] F = H 2 + Z 2 = X 2 + Y 2 + Z 2 (1-3)

[0106] When the magnetic field acts on the magnetostrictive material, the internal magnetic nucleus will be orderly combined and arranged along the direction of the magnetic field, causing the magnetostrictive material to stretch and shrink in volume along the direction of the magnetic field, which is the magnetostrictive effect. However, due to the difference in the material composition of the magnetostrictive material (mainly including iron-nickel alloy, iron-aluminum alloy, iron-cobalt alloy and other metal alloy materials, and terbium-dysprosium-iron alloy and other rare earth metal alloy materials), the trend of volume deformation and magnetic field direction or size change is different, and the stretching and shrinking degree caused by the magnetostrictive effect of different materials is also different. In the linear working area, the relationship between the magnetostrictive coefficient and the axial strain ε can be represented as:

[0107] C (E0 + ΔE) = Δd / d = ε (1-4)

[0108] In the above formula, C is the magnetostrictive coefficient, E0 is the initial magnetic field strength, ΔE is the change amount of the magnetic field strength, Δd is the change amount of the material length in the direction of the magnetic field, and d is the initial length of the stretching material.

[0109] When the external magnetic field changes, the length of the magnetostrictive material changes, thereby changing the distance between the connecting pieces and the outer diameter of the support piece, and further causing the two sensing optical fibers wound on the support piece to produce an optical path difference (i.e. an interference arm length difference), and the relationship between the change amount of the magnetostrictive material and the interference arm length difference Δr can be represented as:

[0110] Δr = KNlΔd (1-5)

[0111] In the above formula, K is the conversion coefficient of the magnetostrictive material and the change amount of the sensing optical fiber, N is the number of winding turns of the sensing optical fiber on the support piece, and l is the strain distance of a turn of the sensing optical fiber on the support piece.

[0112] The optical fiber interference system interference arm length difference causes the optical fiber interference signal to produce a phase difference, and the relationship between the arm length difference Δr and the phase change signal can be represented as:

[0113]

[0114] In the above formula, n is the refractive index of the optical fiber, υ0 is the center wavelength of the interference optical signal, and c0 is the speed of light in vacuum.

[0115] When the optical fiber interference signal is transmitted back to the optical fiber interferometer, the optical fiber interference signal I detected by the photodetector (PD) is PD (t) is as follows:

[0116]

[0117] In the above formula, I0 is the intensity of the laser radiation, k v (0≤k v ≤1) is the interference fringe contrast, is the initial phase difference of the optical fiber interferometer.

[0118] The joint formula (1-4), (1-5), (1-6), (1-7) can be obtained

[0119]

[0120] where I0, k v , π, n, K, N, l, C, d, c0, E0 are all known quantities, the phase change can be demodulated by the interferometer, and the magnetic field strength in the measurement direction can be calculated.

[0121] By measuring the magnetic field strength in the X, Y, and Z axes, the geomagnetic seven elements: horizontal component (H), north component (X), east component (Y), vertical component (Z), magnetic declination (D), magnetic inclination (I), and total field strength (F) can be calculated by formulas (1-1), (1-2), and (1-3).

[0122] Based on the above device, the following method is used for geomagnetic measurement:

[0123] Step 1: Connect the geomagnetic measurement device with the optical fiber interferometer through a multi-core optical cable, and run the optical fiber interferometer to measure the magnetic field change ΔE in real time.

[0124] Step 2: After placing the geomagnetic measurement device at the point to be measured, strictly align the three measurement axes of the geomagnetic measurement device with the north component (X component), east component (Y component), and vertical component (Z component) and fix them.

[0125] Step 3: Calibrate E0; Method 1: Align the three-axis direction of another geomagnetic measurement device with the geomagnetic measurement device to be calibrated, then measure the initial magnetic field strength E0 in the three directions; Method 2: Place the magnetostrictive material in the zero magnetic space through the magnetic field shielding device, so that E0 = 0 for calibration.

[0126] Fourth step: the each axis calibration value E0 is substituted into formula (1-8), and the size of the geomagnetic field strength component on the north component (X component), east component (Y component) and vertical component (Z component) can be calculated.

[0127] Fifth step: the horizontal component (H), magnetic declination (D), magnetic inclination (I) and total field strength (F) can be calculated through formula (1-1), (1-2) and (1-3).

[0128] The magneto-optical conversion structure is used to magnify the magnetostriction of each dimension magnetostrictive material by more than 30 times, and the magnetostriction is applied to the actual length of a circle of sensing optical fiber, and the temperature compensation effect is realized, and the measurement precision and sensitivity of the geomagnetic measurement device are increased.

[0129] The support is used to control the diameter of the sensing optical fiber winding circle, and the bending-resistant optical fiber is used to realize the maximum winding number under the premise of a certain length of the sensing optical fiber; the magneto-optical conversion structure is designed to magnify the magnetostriction of the magnetostrictive material by 3-4 orders of magnitude and effectively transfer the magnetostriction to the sensing optical fiber, thereby greatly increasing the measurement precision and sensitivity of the geomagnetic measurement device.

[0130] In the description of the specification, if the terms "embodiment one", "the embodiment", "in an embodiment", etc. are described, it means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in the invention or at least one embodiment or example of the invention. In the description of the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example; moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in an appropriate manner.

[0131] In the description of the specification, the terms "connection", "installation", "fixation", "setting", "have", etc. are understood in a broad sense, for example, "connection" can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0132] In the description of the specification, the relative terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation without necessarily requiring or implying these entities or operations have any such actual relationship or order. Also, the terms "comprises", "comprising", or any other variations thereof are intended to cover a non-exclusive inclusion, so that a process, method, article, or apparatus including a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or apparatus including the element.

[0133] The above description of the embodiments is to facilitate the understanding and application of the technology by those skilled in the art, and those skilled in the art can easily make various modifications to these examples and apply the general principles described herein to other embodiments without creative labor. Therefore, the present application is not limited to the above embodiments, and modifications to the following cases should be within the scope of protection: ① new technical solutions based on the technical solutions of the present application and combined with existing common knowledge, the technical effects produced by the new technical solutions do not exceed the technical effects of the present application; ② equivalent replacement of part of the features of the technical solutions of the present application using known technology, the technical effects produced are the same as the technical effects of the present application; ③ expandable based on the technical solutions of the present application, the essential content of the expanded technical solutions does not exceed the technical solutions of the present application; ④ equivalent transformation using the contents of the present application specification and drawings, direct or indirect application in other related technical fields.

Claims

1. A magneto-optical conversion structure, characterized in that, The device includes a first support member sleeved on the outside of a magnetostrictive rod. A first sensing optical fiber is wound circumferentially around the first support member. Both ends of the first support member and the magnetostrictive rod are connected via a first transmission unit. The first support member has a first state and a second state with different diameters. When the magnetostrictive rod extends or retracts, the first transmission unit causes the first support member to change between the first state and the second state. The first support member is a cylindrical structure composed of a plurality of first mounting blocks distributed circumferentially along the magnetostrictive rod. The first transmission unit includes a first connector and a first elastic strain gauge. One end of the first strain gauge is connected to the first mounting block, and the other end extends away from the magnetostrictive rod and is connected to the end of the magnetostrictive rod via the first connector.

2. The magneto-optical conversion structure according to claim 1, characterized in that, The plurality of first mounting blocks are identical, and there are multiple first strain gauges, which are evenly distributed at the same angle along the circumference of the magnetostrictive rod.

3. A magneto-optical conversion structure according to any one of claims 1 to 2, characterized in that, The first support member is sleeved at the middle position of the magnetostrictive rod.

4. A push-pull fiber optic magnetic field measurement probe, characterized in that, Includes a magneto-optical conversion structure as described in any one of claims 1 to 3, wherein the magneto-optical conversion structure is connected to a reference module; The comparison module includes a second support member, which is sleeved outside the elastic unit. A second sensing optical fiber is wound around the second support member in the circumferential direction. Both ends of the second support member and the elastic unit are connected through a second transmission unit. The second support member has a third state and a fourth state with different diameters. In the axial direction of the magnetostrictive rod, the elastic unit abuts against the magnetostrictive rod. When the magnetostrictive rod extends / retracts, the elastic unit shortens / extends by the same distance, and the second support changes between the third and fourth states via the second transmission unit.

5. A push-pull fiber optic magnetic field measuring probe according to claim 4, characterized in that, The elastic unit includes an elastic pad and a support rod, with the elastic pad abutting against the support rod in the axial direction. The second support member is a cylindrical structure, which is composed of a plurality of second mounting blocks distributed circumferentially along the magnetostrictive rod; The second transmission unit includes a second strain gauge and a second connector. One end of the second strain gauge is connected to the second mounting block, and the other end extends away from the support rod and is connected to the end of the support rod through the second connector. The elastic gasket is disposed between the second connector and the second support.

6. A push-pull fiber optic magnetic field measurement probe according to claim 5, characterized in that, It also includes a cylindrical shell, the magneto-optical conversion structure and the reference module are both disposed inside the cylindrical shell, the shape of the second connector matches the shape of the inner wall of the cylindrical shell, a limit rod is connected inside the cylindrical shell, the second connector has a limit hole, and the second connector is sleeved outside the limit rod through the limit hole.

7. A push-pull fiber optic magnetic field measurement probe according to claim 4, characterized in that, The first sensing fiber and the second sensing fiber are the same fiber. The first support member and the second support member have the same shape and size. The magnetostrictive rod and the elastic unit have the same length in the initial state. The position of the first support member sleeved on the magnetostrictive rod corresponds to the position of the second support member sleeved on the elastic unit. The first transmission unit and the second transmission unit have the same shape and size. The diameter in the first state is the same as the diameter in the third state. The diameter in the third state is the same as the diameter in the fourth state.

8. A geomagnetic measuring device, characterized in that, The invention includes a push-pull fiber optic magnetic field measurement probe as described in any one of claims 4 to 7, wherein the three push-pull fiber optic magnetic field measurement probes are perpendicular to each other in pairs.

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