Weak magnetic field measuring device and method based on single slit diffraction

Abstract

The invention provides a weak magnetic field measuring device based on single slit diffraction and a method thereof, and relates to the technical field of electromagnetic test. The device comprises a Helmholtz coil, a lever, a single-slit sub-device, a laser, a linear array CCD module development board and a component measurement sub-device. The component measurement sub-device is arranged in the center of the Helmholtz coil, one end of the lever is rigidly connected with the Helmholtz coil, and the single-slit sub-device is hung at the other end. The laser is located in front of the single-slit device, and the linear array CCD module is coaxially aligned with the laser. The Helmholtz coil generates a uniform magnetic field to be measured, and the single-seam device adjusts the stress change by adjusting the water injection rate or the weight mass, so that the initial seam width is changed. The laser serves as a light source and is used for carrying out a single-slit diffraction experiment so as to obtain diffraction light intensity distribution data, and the linear array CCD module is used for collecting and calculating the relation between the single-slit width variation and the vertical and horizontal components of the magnetic field. The problems of low temperature dependence, high cost, insufficient sensitivity and the like of the existing magnetic field measurement technology are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic experiment and testing, and in particular to a weak magnetic field measuring device based on single-slit diffraction and a method thereof. Background Art

[0002] Among existing magnetic field measurement technologies, superconducting quantum interference devices are based on Josephson junctions in superconducting rings, which detect changes in the magnetic field through the flux quantization effect. The highest sensitivity can reach the femtotesla level, but it requires a liquid helium / liquid nitrogen low-temperature environment, the system is complex and the maintenance cost is high.

[0003] Hall effect sensors typically have a sensitivity range of microteslas to milliteslas, based on the linear relationship between the Hall voltage and the magnetic field. Simple optically pumped magnetometers, based on atomic energy level transitions, require a small laser and a rubidium / cesium gas chamber, resulting in high costs.

[0004] The magnetic field measuring instrument uses the lever principle, with a magnetic attraction design at one end and a miniature rangefinder at the other end. The experimental phenomenon is difficult to observe and demonstrate. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide a weak magnetic field measurement device and method based on single-slit diffraction. The present invention solves the problems of existing magnetic field measurement technology such as dependence on low-temperature environment, high cost, insufficient sensitivity and non-intuitive experimental phenomena.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A weak magnetic field measurement device based on single-slit diffraction, comprising:

[0008] Helmholtz coil, lever, single slit sub-device, laser, linear array CCD module development board and component measurement sub-device;

[0009] The component measurement sub-device is placed in the central area of the Helmholtz coil, one end of the lever is rigidly connected to the component measurement sub-device, and the other end is suspended from the single-slit sub-device, the laser is set in front of the single-slit sub-device, and the linear array CCD module development board is located behind the single-slit sub-device and is coaxially aligned with the laser;

[0010] The Helmholtz coil is used to generate a uniform magnetic field to be measured. The single-slit sub-device is used to adjust the water injection volume or the weight mass, and use the lever and the component measurement sub-device to adjust the magnetic force change or expansion and contraction, thereby changing the slit width. The laser is used to perform a single-slit diffraction experiment to obtain diffraction light intensity distribution data. The linear array CCD module development board is used to collect diffraction light intensity distribution data and repeatedly calculate the relationship between the slit width change and the vertical and horizontal components of the magnetic field.

[0011] Preferably, the single slit device comprises:

[0012] The upper part is a spring-supported water tank, and the bottom part is fixed with the first blade;

[0013] The lower 3D printed plate has the second blade fixed on top;

[0014] The water tank and the flat plate are suspended in the air relative to each other through a spring, and two blades form an adjustable single slit.

[0015] Preferably, the component measurement sub-device includes:

[0016] Magnetostrictive materials and magnets.

[0017] Preferably, the linear array CCD module development board is used to collect diffraction light intensity distribution data and calculate multiple times to obtain the relationship between the slit width change and the vertical component and horizontal component of the magnetic field, including:

[0018] Performing mean filtering on the diffraction light intensity distribution data to obtain a dark fringe spacing measurement value;

[0019] Determine the distance from the single slit to the linear array CCD module development board and calculate the slit width change based on the dark pattern spacing measurement value;

[0020] Determining expressions for the vertical component and the horizontal component of the magnetic field according to the variation of the slit width;

[0021] The expression of the slit width variation is:

[0022] Δa=a-a0; a0 represents the initial slit width corresponding to the absence of a magnetic field, and a represents the slit width when a magnetic field exists.

[0023] The expression of the vertical component of the magnetic field is:

[0024] B ⊥ =2.083×10 15 Δa 3 -1.132×10 11 Δa 2 +2.586×10 6 Δa+3.433;

[0025] The expression for the horizontal component is:

[0026] B || =-8.58×10 5 Δa-0.1041.

[0027] Preferably, the lever is an adjustable proportional lever.

[0028] Preferably, the method comprises:

[0029] The uniform magnetic field to be measured is generated by the Helmholtz coil, causing the component measurement sub-device to be displaced or deformed by the magnetic field, and then amplified by the lever to drive the slit width change of the single slit sub-device;

[0030] A laser is used to illuminate a single slit to generate a diffraction spot, and the light intensity distribution data of the secondary bright fringe is collected through a linear array CCD module development board.

[0031] Perform mean filtering on the light intensity data, calibrate the dark fringe position and calculate the average dark fringe spacing, and convert it into actual distance;

[0032] Calculate the current crack width and its variation and invert the vertical and horizontal components of the magnetic field based on the relationship between the crack width variation and the vertical and horizontal components of the magnetic field;

[0033] Perform vector synthesis on the vertical and horizontal components to output the magnitude and direction of the uniform magnetic field to be measured.

[0034] The present invention discloses the following technical effects:

[0035] The present invention provides a weak magnetic field measurement device based on single-slit diffraction, comprising: a Helmholtz coil, a lever, a single-slit sub-device, a laser, a linear array CCD module development board, and a component measurement sub-device; the component measurement sub-device is disposed in the central region of the Helmholtz coil; one end of the lever is rigidly connected to the component measurement sub-device, and the single-slit sub-device is suspended from the other end; the laser is disposed directly in front of the single-slit sub-device; and the linear array CCD module development board is located behind the single-slit sub-device and coaxially aligned with the laser; the Helmholtz coil is used to generate a uniform magnetic field to be measured; the single-slit sub-device is used to adjust the magnetic force change or expansion and contraction by adjusting the water injection volume or the mass of the weight, thereby changing the slit width using the lever and the component measurement sub-device; the laser is used to perform a single-slit diffraction experiment to obtain diffracted light intensity distribution data; and the linear array CCD module development board is used to collect the diffracted light intensity distribution data and repeatedly calculate the relationship between the slit width change and the vertical and horizontal components of the magnetic field. The present invention combines the principle of levers with optical phenomena to significantly improve measurement accuracy and visualization. Compared to existing complex magnetic field measurement technologies, this solution simplifies the system structure, reduces maintenance costs, and facilitates teaching and research. Furthermore, the device can process data in real time and is adaptable to measuring both vertical and horizontal magnetic fields, comprehensively improving the flexibility and efficiency of magnetic field measurements. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 A first structural diagram of a weak magnetic field measurement device based on single-slit diffraction provided by an embodiment of the present invention;

[0038] Figure 2 A second structural diagram of a weak magnetic field measurement device based on single-slit diffraction provided by an embodiment of the present invention;

[0039] Figure 3 A schematic diagram of a single slit device provided in an embodiment of the present invention;

[0040] Figure 4 The single-slit diffraction light intensity distribution diagram provided by the embodiment of the present invention, wherein: Figure 4 (a) is the original data light intensity distribution diagram, Figure 4 (b) is the light intensity distribution diagram corresponding to the data after mean filtering;

[0041] Figure 5 A fitting image of the vertical component of the magnetic field provided in an embodiment of the present invention;

[0042] Figure 6 This is a fitting image of the horizontal component of the magnetic field provided by an embodiment of the present invention.

[0043] Reference numerals:

[0044] 1- Lever, 2- Single-slit device, 3- Laser, 4- Magnet, 5- Helmholtz coil, 6- Linear CCD module development board, 7- Magnetostrictive material. DETAILED DESCRIPTION

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

[0046] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] like Figure 1-2 As shown, the present invention provides a weak magnetic field measurement device based on single-slit diffraction, comprising:

[0048] Helmholtz coil 5, lever 1, single slit sub-device, laser 3, linear array CCD module development board 6 and component measurement sub-device;

[0049] The component measurement sub-device is arranged in the central area of the Helmholtz coil 5, one end of the lever 1 is rigidly connected to the component measurement sub-device, and the other end is suspended from the single-slit sub-device, the laser 3 is arranged in front of the single-slit sub-device, and the linear array CCD module development board 6 is located behind the single-slit sub-device and is coaxially aligned with the laser 3;

[0050] The Helmholtz coil 5 is used to generate a uniform magnetic field to be measured. The single-slit sub-device is used to adjust the water injection amount or the weight mass, and use the lever 1 and the component measurement sub-device to adjust the magnetic force change or expansion and contraction amount, thereby changing the slit width. The laser 3 is used to perform a single-slit diffraction experiment to obtain diffraction light intensity distribution data. The linear array CCD module development board 6 is used to collect diffraction light intensity distribution data and calculate multiple times to obtain the relationship between the slit width change and the vertical component and horizontal component of the magnetic field.

[0051] Specifically, the present invention proposes a new experimental approach to measuring the vertical magnetic field by combining the force exerted on a magnet in a magnetic field with lever 1 and a single slit. Considering that the magnitude of the force exerted on a magnet in a magnetic field is difficult to measure and the experimental phenomenon is not obvious, lever 1 is used to convert the change in the force exerted on the magnet into a change in the width of the single slit. The experimental phenomenon can be clearly observed with the naked eye through single slit diffraction.

[0052] By collecting the light intensity distribution generated by a single slit using a linear CCD and processing it with a computer, a light intensity distribution graph can be obtained. The slit width and its variation can then be determined, and a curve showing the relationship between the slit width variation and the magnetic field magnitude can be obtained. In practical measurements, only the slit width variation needs to be measured to determine the magnetic field magnitude. To ensure that the single slit width consistently produces a clear single slit diffraction phenomenon during measurement, a single slit device with an adjustable initial slit width was used.

[0053] At the same time, for the measurement of the horizontal magnetic field, magnetostrictive material 7 is used to replace the magnet in the experimental device for measuring the vertical magnetic field. By utilizing its property of changing its own length in the magnetic field as the magnetic field size changes, the relationship curve between the size of the horizontal magnetic field and the change in the gap width can be obtained through experiments.

[0054] Finally, the magnitude and direction of the magnetic field to be measured can be obtained by vector synthesis of the two mutually perpendicular horizontal magnetic fields and vertical magnetic fields.

[0055] More specifically, a Helmholtz coil 5 generates a weak uniform magnetic field, connected to a magnet 4 or magnetostrictive material 7 via a lever 1, with a single-slit device 2 suspended from the other end. Lever 1 adjusts the magnetic force or the amount of expansion and contraction, thereby changing the slit width. A single-slit diffraction experiment is then conducted using a laser 3. A linear array CCD module development board 6 is used to capture the diffracted light intensity distribution and perform noise reduction processing to determine the spacing of the diffraction fringe patterns. Based on the measurement results, a fitted relationship is obtained between the vertical and horizontal components of the magnetic field and the change in slit width. When measuring an unknown magnetic field, this relationship can be used to determine the magnitude and direction of the magnetic field.

[0056] Further, such as Figure 3 As shown, the single slit device 2 includes:

[0057] The upper part is a spring-supported water tank, and the bottom part is fixed with the first blade;

[0058] The lower 3D printed plate has the second blade fixed on top;

[0059] The water tank and the flat plate are suspended in the air relative to each other through a spring, and two blades form an adjustable single slit.

[0060] Furthermore, the component measurement sub-device includes:

[0061] Magnetostrictive material 7 and magnet 4.

[0062] Specifically, one end of a lever 1 is connected to a magnet 4 or magnetostrictive material 7, and the other end houses a single-slit device 2. The upper half of the device consists of a rectangular water tank with a blade fixed to its underside; the lower half consists of a 3D-printed flat plate with another blade fixed to its top. The water tank is supported by four springs, allowing the blade at the bottom of the tank and the blade at the top of the plate to form a single slit. The slit width can be adjusted by pumping water into the water tank or adjusting the weight, resulting in distinct diffraction fringes on the screen.

[0063] Place the magnet 4 or magnetostrictive material 7 at the center of the Helmholtz coil 5, vary the power supply voltage, and record the current and voltage corresponding to the different magnetic fields. Conduct experiments based on this data. During the experiment, pay attention to the slit width range, which should be determined based on the laser used in the experiment. The slit width should not exceed the range corresponding to diffraction.

[0064] Furthermore, the linear array CCD module development board 6 is used to collect diffraction light intensity distribution data and calculate multiple times to obtain the relationship between the slit width change and the vertical component and horizontal component of the magnetic field, including:

[0065] Performing mean filtering on the diffraction light intensity distribution data to obtain a dark fringe spacing measurement value;

[0066] Determine the distance from the single slit to the linear array CCD module development board 6 and calculate the slit width change based on the dark pattern spacing measurement value;

[0067] Determining expressions for the vertical component and the horizontal component of the magnetic field according to the variation of the slit width;

[0068] Specifically, after recording the current and voltage corresponding to different magnetic fields, magnet 4 or magnetostrictive material 7 is placed at the center of the magnetic field. Magnetic fields of varying magnitudes are applied, starting with no magnetic field and increasing in magnitude, while a single-slit diffraction experiment is performed at the other end of lever 1.

[0069] The linear array CCD module development board 6 is used to receive the diffracted light. Since the middle bright fringe is too bright and exceeds the measurement upper limit of the linear array CCD module development board 6, the signal is received starting from the secondary bright fringe.

[0070] like Figure 4 As shown, the corresponding Excel format data is exported (Note: the data is the light intensity. This linear array CCD module development board 6 has a total of 3647 units, and the effective length that can receive light intensity is 29mm, which can collect 3647 pixels), and the data is processed by mean filtering.

[0071] in,

[0072]

[0073] Δa=a-a0 (4)

[0074] in, is the average value of five measurements of the dark fringe spacing (pixel points), Δx1, Δx2, Δx3, Δx4, and Δx5 are the measured values of the dark fringe spacing (pixel points), Δx is the actual distance between dark fringes, λ is the laser wavelength, a is the slit width after applying the magnetic field, a0 is the initial slit width, L is the distance from the single slit to the linear array CCD module development board 6, and Δa is the slit width change.

[0075] The light intensity distribution is analyzed by Figure 4 (b) Obtain the distance Δx between five adjacent troughs k , k=1,2,3,4,5, and then take the average value The actual distance Δx between dark fringes is obtained from formula (2), the corresponding gap width a in the presence of a magnetic field is obtained from formula (3), and the gap width change Δa is calculated using formula (4).

[0076] Apply different magnetic fields to obtain the corresponding gap width change Δa. According to the experimental data, the gap width change Δa is the horizontal coordinate, and the vertical component of the magnetic field B is the vertical component of the magnetic field B. ⊥ , horizontal component of magnetic field B || As the vertical axis, draw a data scatter plot and a fitting curve, such as Figure 5 、 Figure 6 shown.

[0077] The experiment applied magnetic fields ranging from 8.6 to 44.3 Gs (vertical) and 1.06 to 50.7 Gs (horizontal). The corresponding diffraction fringe spacing and the change in single-slit slit width were measured under different magnetic fields. A 0.5 Gs change in magnetic field showed a significant change in the single-slit diffraction fringe spacing. Given the adjustable magnification of lever 1, the sensitivity of magnetic field measurements could be further improved.

[0078] Through experiments, the expression obtained is as follows:

[0079] ①Expression of vertical component of magnetic field:

[0080] B ⊥ =2.083×10 15 Δa 3 -1.132×10 11 Δa 2 +2.586×10 6 Δa+3.433 (5)

[0081] ②Horizontal component expression:

[0082] B || =-8.58×10 5 Δa-0.1041 (6)

[0083] In formulas (5) and (6), the magnetic induction intensity B ⊥ and B || The unit of is Gs, and the unit of slit width change Δa is m.

[0084] In the experiment, when a magnetic field is applied, the magnetostrictive material 7 stretches, effectively pulling it upward and narrowing the single slit. Therefore, the slit width change Δa in formula (6) is negative. When measuring an unknown magnetic field, simply measuring the slit width change Δa allows the magnitude of the magnetic field to be determined based on the relationship between the vertical and horizontal components of the magnetic field and Δa.

[0085] This embodiment further provides a weak magnetic field measurement method based on single-slit diffraction, the method comprising:

[0086] Step 100: Generate a uniform magnetic field to be measured by a Helmholtz coil, causing the component measurement sub-device to be displaced or deformed by the magnetic field, and then amplified by a lever to drive the slit width of the single slit sub-device to change;

[0087] Step 200: Using a laser to illuminate a single slit to generate a diffraction spot, and using a linear array CCD module development board to collect light intensity distribution data of the secondary bright fringe;

[0088] Step 300: Perform mean filtering on the light intensity data, calibrate the dark fringe positions and calculate the average dark fringe spacing, and convert it into actual distance;

[0089] Step 400: Calculate the current slit width and its variation and invert the vertical and horizontal components of the magnetic field based on the relationship between the slit width variation and the vertical and horizontal components of the magnetic field;

[0090] Step 500: Perform vector synthesis on the vertical component and the horizontal component, and output the magnitude and direction of the uniform magnetic field to be measured.

[0091] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0092] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A weak magnetic field measurement device based on single-slit diffraction, characterized in that: include: Helmholtz coil, lever, single slit sub-device, laser, linear array CCD module development board and component measurement sub-device; The component measurement sub-device is arranged in the central area of the Helmholtz coil, one end of the lever is rigidly connected to the component measurement sub-device, and the other end is suspended from the single-slit sub-device, the laser is placed directly in front of the single-slit sub-device, and the linear array CCD module development board is located behind the single-slit sub-device and is coaxially aligned with the laser; The Helmholtz coil is used to generate a uniform magnetic field to be measured. The single-slit sub-device is used to adjust the water injection volume or the weight mass, and use the lever and the component measurement sub-device to adjust the magnetic force change or expansion and contraction, thereby changing the slit width. The laser is used to perform a single-slit diffraction experiment to obtain diffraction light intensity distribution data. The linear array CCD module development board is used to collect diffraction light intensity distribution data and repeatedly calculate the relationship between the slit width change and the vertical and horizontal components of the magnetic field.

2. The weak magnetic field measurement device based on single-slit diffraction according to claim 1, characterized in that: The single slit device comprises: The upper part is a spring-supported water tank, and the bottom part is fixed with the first blade; The lower 3D printed plate has the second blade fixed on top; The water tank and the flat plate are suspended in the air relative to each other through a spring, and two blades form an adjustable single slit.

3. The weak magnetic field measurement device based on single-slit diffraction according to claim 1, characterized in that: The component measurement sub-device includes: Magnetostrictive materials and magnets.

4. The weak magnetic field measurement device based on single-slit diffraction according to claim 1, characterized in that: The linear array CCD module development board is used to collect diffraction light intensity distribution data and calculate the relationship between the slit width change and the vertical and horizontal components of the magnetic field multiple times, including: Performing mean filtering on the diffraction light intensity distribution data to obtain a dark fringe spacing measurement value; Determine the distance from the single slit to the linear array CCD module development board and calculate the slit width change based on the dark pattern spacing measurement value; Determining expressions for the vertical component and the horizontal component of the magnetic field according to the variation of the slit width; The expression of the slit width variation is: Δa=a-a0; a0 represents the initial slit width corresponding to the absence of a magnetic field, and a represents the slit width when a magnetic field exists. The expression of the vertical component of the magnetic field is: B ⊥ =2.083×10 15 Δa 3 -1.132×10 11 Δa 2 +2.586×10 6 Δa+3.433; The expression for the horizontal component is: B || =-8.58×10 5 Δa-0.1041。 5. The weak magnetic field measurement device based on single-slit diffraction according to claim 1, characterized in that: The lever is an adjustable proportional lever.

6. A weak magnetic field measurement method based on single-slit diffraction, applied to the device according to any one of claims 1 to 4, characterized in that: The method comprises: The uniform magnetic field to be measured is generated by the Helmholtz coil, causing the component measurement sub-device to be displaced or deformed by the magnetic field, and then amplified by the lever to drive the slit width change of the single slit sub-device; A laser is used to illuminate a single slit to generate a diffraction spot, and the light intensity distribution data of the secondary bright fringe is collected through a linear array CCD module development board. Perform mean filtering on the light intensity data, calibrate the dark fringe position and calculate the average dark fringe spacing, and convert it into actual distance; Calculate the current crack width and its variation and invert the vertical and horizontal components of the magnetic field based on the relationship between the crack width variation and the vertical and horizontal components of the magnetic field; Perform vector synthesis on the vertical and horizontal components to output the magnitude and direction of the uniform magnetic field to be measured.

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