A weak magnetic field measurement system and method based on the torsional optical lever method

Abstract

The application discloses a weak magnetic field measuring system and method based on a torsion optical lever method, and belongs to the technical field of electromagnetic measurement. The system comprises a lead wire, a magnet assembly, a scale disc, an optical lever, a mirror piece, a laser emitter, a data recording device and a data processing unit. When the magnet assembly is twisted, the lead wire drives the magnet assembly to return to the initial position. When the magnet assembly is twisted, the optical lever and the scale disc are driven to rotate. The laser emitter and the data recording device are sequentially arranged on the side of the scale disc away from the torsion support, the mirror piece is fixedly installed in the middle of the optical lever, the laser emitter emits laser to the mirror piece, the laser is reflected on the scale line of the scale disc, and the data recording device is used for recording the light spot position of the laser on the scale line. The data processing unit calculates the magnetic field intensity of the weak magnetic field according to the light spot position of the laser on the scale line. The application realizes the measurement of the weak magnetic field through a simple device.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic measurement technology, specifically relating to a weak magnetic field measurement system and method based on the torsion balance optical lever method. Background Technology

[0002] A weak magnetic field refers to a magnetic field with relatively low intensity, typically in the millitalas or microteslas range. Measuring such magnetic fields is crucial for many fields, including but not limited to biomedical imaging, geophysics, materials science, and fundamental physics research. Measuring weak magnetic fields can help scientists study brain activity, probe the Earth's internal structure, investigate the properties of magnetic materials, and even explore dark matter in the universe. Here are some common methods for measuring weak magnetic fields:

[0003] (1) Fluxgate method: Fluxgate sensors are based on the principle of magnetic induction and detect the position, velocity and direction of a target object by detecting changes in the magnetic field. However, this method has certain requirements on the shape and size of the target object, requires a certain amount of power consumption, and has a relatively short working distance.

[0004] (2) Superconducting quantum interference device: A superconducting quantum interference device is a highly sensitive magnetic flux measurement device that can detect very weak magnetic field changes. However, superconducting quantum interference device systems usually need to operate at extremely low temperatures, which limits their portability and cost-effectiveness.

[0005] (3) Magnetic resonance method: The magnetic resonance method uses the changes in the quantum state of matter to precisely measure the magnetic field, and is often used to measure uniform constant magnetic fields. However, this method usually requires complex equipment and has a high cost.

[0006] (4) Magnetoresistive effect method: Magnetoresistive sensors use the property that the resistance of a material changes with the magnetic field to measure the magnetic field. However, magnetoresistive sensors may be affected by temperature changes and require accurate temperature compensation.

[0007] In summary, the shortcomings of existing technologies are that it is difficult to simultaneously guarantee measurement accuracy and cost-effectiveness, and the operation procedures are cumbersome. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a weak magnetic field measurement system and method based on the torsion balance optical lever method, which solves the problems of difficulty in simultaneously ensuring measurement accuracy and cost-effectiveness, and cumbersome operation steps in the prior art.

[0009] This invention provides the following technical solution:

[0010] In the first aspect, a weak magnetic field measurement system based on the torsion balance optical lever method is provided, including lead wire, magnet assembly, scale, optical lever, reflector, laser emitter, data recording device and data processing unit;

[0011] A lead wire is wound around the middle of the magnet assembly. The lead wire is in a taut state. When the magnet assembly is twisted, the lead wire pulls the magnet assembly back to its initial position.

[0012] One end of the optical lever is slidably connected to a magnet assembly, and when the magnet assembly is twisted, it causes the optical lever to rotate.

[0013] The dial is fixedly positioned below the optical lever;

[0014] The laser emitter and the data recording device are sequentially arranged on the side of the scale away from the torsion balance bracket. The reflector is fixedly installed in the middle of the optical lever. The laser emitter emits laser light into the reflector, and the laser light is reflected onto the scale line of the scale. The data recording device is used to record the position of the laser spot on the scale line.

[0015] The data processing unit is connected to the data recording device and calculates the magnetic field strength of the weak magnetic field based on the position of the laser spot on the scale line.

[0016] As an optional technical solution of the present invention, it also includes a torsion balance bracket; the two ends of the lead wire are respectively fixed to the top and bottom of the torsion balance bracket.

[0017] As an optional technical solution of the present invention, the magnet assembly includes a magnet fixing rod and a magnet; the magnet is installed at both ends of the magnet fixing rod.

[0018] As an optional technical solution of the present invention, the bottom of the magnet fixing rod is provided with a sliding groove, and the two ends of the optical lever are provided with support columns; the support column at one end of the optical lever is connected to the magnet fixing rod through the sliding groove. When the magnet fixing rod is twisted, the support column slides in the sliding groove, causing the optical lever to rotate.

[0019] As an optional technical solution of the present invention, the diameter of the support column is equal to the width of the sliding groove.

[0020] As an optional technical solution of the present invention, the middle part of the optical lever is a hollow structure, and the reflective lens is fixed in the hollow structure.

[0021] Secondly, a measurement method is provided based on the weak magnetic field measurement system based on the torsion balance optical lever method described in the first aspect, comprising:

[0022] Obtain the initial spot position and deflection spot position of the laser;

[0023] The laser deflection angle is calculated based on the initial spot position and the deflection spot position.

[0024] Based on the laser deflection angle and the pre-constructed deflection angle-magnetic field strength curve, the magnetic field strength of the weak magnetic field is obtained.

[0025] As an optional technical solution of the present invention, the process of constructing the deflection angle-magnetic field intensity curve includes:

[0026] A current-carrying straight copper wire is placed at the magnet assembly. The magnetic field strength is changed by adjusting the current flowing through the wire, and the magnetic field strength under different current magnitudes is calculated. , is represented as:

[0027] ;

[0028] in, Indicates the magnitude of the current. Represents the permeability of free space. Indicates the length of a straight copper conductor. Indicates the distance between the straight copper wire and the magnet assembly;

[0029] The beam deflection distance is obtained from the beam position before and after the change in current. ;

[0030] The deflection angle is calculated based on the light spot deflection distance and is expressed as follows:

[0031] ;

[0032] in, Indicates the deflection angle. Indicates the radius of the scale plate;

[0033] The calculated deflection angle is correlated with the magnetic field strength to construct the deflection angle-magnetic field strength curve.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] The weak magnetic field measurement system based on the torsion balance optical lever method provided by this invention achieves two-stage amplification of weak magnetic fields through the combination of torsion balance and optical lever, thereby improving measurement accuracy and enabling the measurement of weak magnetic fields with a simple device. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of a measuring device for measuring weak magnetic fields based on the torsion balance optical lever method provided in an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the structure of the magnet fixing rod provided in an embodiment of the present invention;

[0038] Figure 3This is a schematic diagram of the optical lever structure provided in an embodiment of the present invention;

[0039] Figure 4 This is a schematic diagram of the magnification principle provided in an embodiment of the present invention.

[0040] In the diagram: 1 is the torsion balance bracket, 2 is the lead wire, 3 is the magnet fixing rod, 4 is the magnet, 5 is the dial, 6 is the optical lever, 7 is the bearing, 8 is the reflector, 9 is the laser emitter, 10 is the data recording device, 11 is the fixing rod, 12 is the fixing base, 13 is the optical base plate, 14 is the sliding groove, and 15 is the support column. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0042] Example 1

[0043] This embodiment provides a weak magnetic field measurement system based on the torsion balance optical lever method.

[0044] like Figure 1 As shown, the system includes a torsion balance bracket 1, lead wire 2, magnet assembly, dial 5, optical lever 6, reflector 8, laser emitter 9, data recording device 10, and data processing unit.

[0045] The torsion balance bracket 1 is mounted on the optical base plate 13, and the dial 5, laser emitter 9, and data recording device 10 are mounted on the optical base plate 13 via the fixing rod 11 and the fixing base 12.

[0046] A lead wire 2 is wound around the middle of the magnet assembly. The lead wire 2 is in a straight state. When the magnet assembly is twisted, the lead wire 2 drives the magnet assembly back to its initial position.

[0047] Furthermore, the magnet assembly includes a magnet fixing rod 3 and a magnet 4; the magnet 4 is mounted at both ends of the magnet fixing rod 3. The middle portion of the lead wire 2 is wound around the middle portion of the magnet fixing rod 3, and the two ends of the lead wire 2 are respectively fixed to the top and bottom of the torsion balance bracket 1. When a weak magnetic field acts on the magnet on the magnet fixing rod, the magnet fixing rod will undergo a slight torsion. Due to the elasticity of the lead wire, it will generate a restoring torque proportional to the torsion angle, causing the magnet fixing rod to return to its original position.

[0048] Furthermore, such as Figure 2 As shown, the bottom of the magnet fixing rod 3 is provided with a sliding groove 14. Figure 3As shown, the optical lever 6 has support columns 15 at both ends. One support column 15 at one end of the optical lever 6 is connected to the magnet fixing rod 3 via a sliding groove 14. When the magnet fixing rod 3 twists, the support column 15 slides within the sliding groove 14, causing the optical lever 6 to rotate. The diameter of the support column 15 is equal to the width of the sliding groove 14. The height of the optical lever 6 is lower than that of the magnet fixing rod 3, and the support column 15 on the optical lever 6 fits perfectly into the sliding groove 14.

[0049] One end of the optical lever 6 is slidably connected to a magnet assembly. When the magnet assembly is twisted, it causes the optical lever 6 to rotate. The dial 5 is fixedly disposed below the optical lever 6 and does not rotate.

[0050] The laser emitter 9 and the data recording device 10 are sequentially arranged on the side of the scale 5 away from the torsion balance bracket 1. The reflector 8 is fixedly installed in the middle of the optical lever 6. The laser emitter 9 emits laser light into the reflector 8, and the laser light is reflected onto the scale line of the scale 5. The data recording device 10 is used to record the position of the laser spot on the scale line. Figure 1 The blue line in the middle represents the laser circuit.

[0051] Furthermore, the middle part of the optical lever 6 is a hollow structure, which reduces weight and decreases frictional resistance between structures, and the reflective lens 8 is fixed inside the hollow structure.

[0052] The data processing unit is connected to the data recording device 10 and calculates the magnetic field strength of the weak magnetic field based on the position of the laser spot on the scale line. In this embodiment, the data recording device 10 is a CCD.

[0053] In this embodiment, the magnet fixing rod 3 has a length of 250-350mm, a width and height of 4-6mm, a sliding groove length of 220-320mm, a width of 2-3mm, and a depth of 3-5mm; the optical lever 6 has a length of 10-30mm, a width and height of 5-10mm, and a support column diameter of 2-3mm and a height of 4-6mm.

[0054] In this embodiment, a reasonable mechanical structure is used to amplify the subtle influence of the weak magnetic field on the torsion balance, and optical amplification is used to make the deflection angle more significant. For example... Figure 4 As shown, the principle of optical amplification is:

[0055] The distance between the center of the magnet fixing rod and the center of the optical lever is L, and the distance between the center of the magnet fixing rod and the support column of the optical lever is [missing information]. The angle of the magnet fixing rod is The half-length of the light lever is The angle of deviation is .

[0056] When the magnet fixing rod is deflected by the torque of a weak magnetic field, the distance L between the center of the magnet fixing rod and the center of the optical lever remains unchanged. , In the triangle formed by L, we obtain and The functional relationship between them:

[0057] ;

[0058] ;

[0059] get:

[0060] .

[0061] Because the torsion balance has a small torsion angle, an approximate relationship can be used. , , Therefore:

[0062]

[0063] In this embodiment, =9cm, L=22cm, therefore the magnification factor of the deflection angle of the magnet fixing rod by the optical lever is 13 / 9 times.

[0064] Working principle:

[0065] During measurement, the system is first placed still until the magnet fixing rod 3 comes to rest. The laser emitter 9 is adjusted so that the laser beam is reflected by the reflector 8 and incident on the 0 mark of the scale 5. The data recording device 10 records the initial position of the laser beam at this time. A straight copper wire of known length is placed near the small magnet 4, and a current is applied to the straight copper wire to generate a magnetic field. Under the action of the magnetic field, the magnet fixing rod 3 rotates, thereby driving the optical lever 6 and the reflector 8 to rotate, which further causes the position of the laser beam on the wall of the scale 5 to deflect. The data recording device 10 records the position of the laser beam after deflection. The magnetic field strength of the weak magnetic field can be fitted by data processing of the initial position and the deflection position.

[0066] Example 2

[0067] This embodiment provides a measurement method for the weak magnetic field measurement system based on the torsion balance optical lever method described in Embodiment 1, including:

[0068] Step 1: Obtain the initial spot position and deflection spot position of the laser.

[0069] Step 2: Calculate the laser deflection angle based on the initial spot position and the deflection spot position.

[0070] Step 3: Based on the laser deflection angle and the pre-constructed deflection angle-magnetic field strength curve, the magnetic field strength of the weak magnetic field is obtained.

[0071] The process of constructing the deflection angle-magnetic field intensity curve includes:

[0072] A current-carrying straight copper wire is placed at the magnet assembly. The magnetic field strength is changed by adjusting the current flowing through the wire, and the magnetic field strength under different current magnitudes is calculated. , is represented as:

[0073] ;

[0074] in, Indicates the magnitude of the current. Represents the permeability of free space. Indicates the length of a straight copper conductor. This indicates the distance between the straight copper wire and the magnet assembly.

[0075] The beam deflection distance is obtained from the beam position before and after the change in current. .

[0076] The deflection angle is calculated based on the light spot deflection distance and is expressed as follows:

[0077] ;

[0078] in, Indicates the deflection angle. This indicates the radius of the scale plate.

[0079] The calculated deflection angle is correlated with the magnetic field strength, and the current is gradually increased in increments of 0.1A to construct the deflection angle-magnetic field strength curve.

[0080] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0081] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0082] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A weak magnetic field measurement system based on the torsional optical lever method, characterized by: It comprises a lead wire (2), a magnet assembly, a scale dial (5), a light lever (6), a mirror piece (8), a laser emitter (9), a data recording device (10) and a data processing unit. The middle part of the magnet assembly is provided with the lead wire (2) in a straightened state, and the lead wire (2) drives the magnet assembly to return to the initial position when the magnet assembly is twisted. One end of the light lever (6) is slidingly connected to the magnet assembly, and the light lever (6) is driven to rotate when the magnet assembly is twisted. The scale dial (5) is fixedly arranged below the light lever (6). The laser emitter (9) and the data recording device (10) are arranged in sequence on the side of the scale dial (5) away from the torsion support (1), the mirror piece (8) is fixedly installed in the middle part of the light lever (6), the laser emitter (9) emits laser to the mirror piece (8), and the laser is reflected on the scale line of the scale dial (5), and the data recording device (10) is used for recording the light spot position of the laser on the scale line. The data processing unit is connected to the data recording device (10), and the magnetic field strength of the weak magnetic field is calculated according to the light spot position of the laser on the scale line. The magnet assembly comprises a magnet fixing rod (3) and a magnet (4), and the magnet (4) is installed at both ends of the magnet fixing rod (3). The bottom of the magnet fixing rod (3) is provided with a sliding groove (14), and the both ends of the light lever (6) are provided with support columns (15); one end of the support column (15) of the light lever (6) is connected to the magnet fixing rod (3) through the sliding groove (14), and when the magnet fixing rod (3) is twisted, the support column (15) slides in the sliding groove (14), driving the light lever (6) to rotate.

2. The weak magnetic field measurement system based on the torsional optical lever method according to claim 1, characterized in that: It also comprises a torsion support (1). The both ends of the lead wire (2) are fixed to the top and bottom of the torsion support (1) respectively.

3. The weak magnetic field measurement system based on the torsional optical lever method according to claim 1, characterized in that: The diameter of the support column (15) is equal to the width of the sliding groove (14).

4. The weak magnetic field measurement system based on the torsional optical lever method according to claim 1, characterized in that: The middle part of the light lever (6) is a hollow structure, and the mirror piece (8) is fixed in the hollow structure.

5. A measuring method for a weak magnetic field measuring system based on the torsional optical lever method according to any one of claims 1 to 4, characterized in that, It comprises: obtaining the initial light spot position and the deflected light spot position of the laser; calculating the laser deflection angle according to the initial light spot position and the deflected light spot position; obtaining the magnetic field strength of the weak magnetic field based on the laser deflection angle and the pre-constructed deflection angle-magnetic field strength curve.

6. The measurement method according to claim 5, characterized in that, The construction process of the deflection angle-magnetic field strength curve comprises: The energized straight copper wire is placed at the magnet assembly, the magnetic field intensity is changed by adjusting the current flowing through the straight copper wire, and the magnetic field intensity under different current sizes is calculated , is expressed as: ； wherein, represents the current size, represents the vacuum permeability, represents the length of the straight copper wire, represents the distance of the straight copper wire from the magnet assembly; The deflection distance of the light spot is obtained according to the positions of the light spot before and after the current is changed ; calculating the deflection angle according to the light spot deflection distance, which is expressed as: ； wherein, denotes the deflection angle, denotes the radius of the scale plate; corresponding the calculated deflection angle with the magnetic field strength to construct the deflection angle-magnetic field strength curve.

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