A device and method for measuring extremely weak magnetic field signals

Abstract

The application discloses a kind of extremely weak magnetic field signal measuring device and method, it is related to weak magnetic field measurement technical field, comprising: first, second vector sensor is respectively arranged in the center area of first, second non-magnetic turntable, first, second non-magnetic turntable is respectively connected with first, second support pole vertically, first support pole and second support pole are vertically arranged, and are linked through first gear and second gear, first support pole is also provided with encoding disc;When driving motor drives first support pole rotation, first, second vector sensor rotates synchronously, and the first and second magnetic field modulation signals are respectively output;While encoding disc rotates synchronously, so that photoelectric detector outputs electric pulse reference signal;Analysis module analyzes and processes the first, second magnetic field modulation signal and reference signal received to determine the three-dimensional magnetic field component in space.The application realizes the accurate measurement of background magnetic field in extremely weak magnetic environment.

Description

Technical Field

[0001] This application relates to the field of weak magnetic field measurement technology, and in particular to a measuring device and method for extremely weak magnetic field signals. Background Technology

[0002] Weak magnetic fields play a crucial role in modern science and research. Although their intensity is extremely low, they are ubiquitous in nature and in biological activities. Precise detection and analysis of these weak magnetic fields not only deepen our understanding of the magnetic characteristics of matter but also provide a solid foundation for the development of sensitive sensors, the improvement of information technology, and the optimization of environmental monitoring methods. Meanwhile, advancements in this field are creating new opportunities for clinical medical research. Magnetoencephalography (MEG) is an imaging technique that uses extremely weak biomagnetic signals from the human body to capture changes in the magnetic field generated by the firing of neurons in the brain. It can perform brain magnetic field measurements with millisecond-level temporal resolution and extremely high sensitivity, thus enabling non-invasive disease diagnosis. Measurement of extremely weak magnetic fields not only provides a unique perspective for the early diagnosis and intervention of neurological diseases but also lays the foundation for further revealing the relationship between brain function and structure.

[0003] When performing measurements in extremely weak magnetic fields, external magnetic interference can directly affect the results, necessitating the use of magnetic shielding devices to isolate stray magnetic fields from the environment. Magnetic shielding devices are typically made of highly permeable materials and can provide a measurement environment on the order of nT to pT. Through effective magnetic shielding, researchers can obtain more accurate and reliable magnetic field data, ensuring the accuracy of experimental results.

[0004] Currently, there are no mature methods for measuring near-zero magnetic fields, especially in applications requiring precise measurement of magnetic field vectors, where existing technologies cannot provide effective solutions. Traditional magnetic field measurement tools, such as fluxgate magnetometers, while offering high sensitivity, still suffer from calibration problems in extremely weak magnetic environments. Therefore, there is an urgent need for new methods to accurately measure the background magnetic field in extremely weak magnetic environments. Summary of the Invention

[0005] The purpose of this application is to provide a device and method for measuring extremely weak magnetic field signals, which can realize the accurate measurement of the background magnetic field in extremely weak magnetic environments.

[0006] To achieve the above objectives, this application provides the following solution:

[0007] In a first aspect, this application provides a measuring device for extremely weak magnetic field signals, comprising:

[0008] The system comprises a first vector sensor, a second vector sensor, a first non-magnetic turntable, a second non-magnetic turntable, a first support rod, a second support rod, a light source, a photodetector, an encoder disk, a drive motor, an analysis module, and a frame.

[0009] The system comprises the following components: a first vector sensor located at the center of the surface of a first non-magnetic turntable; a vertical connection between the center of the bottom surface of the first non-magnetic turntable and one end of a first support rod; the other end of the first support rod passing vertically through the center of the encoder disk and connected to the shaft of a drive motor; a second vector sensor located at the center of the surface of a second non-magnetic turntable; a vertical connection between the center of the bottom surface of the second non-magnetic turntable and one end of a second support rod; the other end of the second support rod connected to the frame via a bearing; a drive motor located below the frame; a bearing located above the frame with its axis perpendicular to the drive motor's axis; a first gear on the first support rod; a second gear on the second support rod; both gears having the same number of teeth; and linkage between the first and second support rods via the first and second gears; one half of the encoder disk being a light-transmitting area and the other half being an opaque area; a light source and a photodetector located on opposite sides of the encoder disk, and not rotating with the encoder disk; a beam of light emitted by the light source only illuminates the photosensitive surface of the photodetector through the light-transmitting area of ​​the encoder disk; and a light source, photodetector, and analysis module located below the frame.

[0010] When the drive motor drives the first support rod to rotate, the encoder disk and the second support rod rotate synchronously with the first support rod, the first non-magnetic turntable and the second non-magnetic turntable rotate synchronously with the first support rod and the second support rod, and the first vector sensor and the second vector sensor rotate synchronously with the first non-magnetic turntable and the second non-magnetic turntable, respectively.

[0011] While rotating, the first vector sensor outputs a first magnetic field modulation signal to the analysis module;

[0012] While rotating, the second vector sensor outputs a second magnetic field modulation signal to the analysis module;

[0013] The photodetector is used to output an electrical pulse reference signal to the analysis module while the encoder disk rotates.

[0014] The analysis module is used to analyze and process the received first magnetic field modulation signal, second magnetic field modulation signal and electric pulse reference signal to determine the three-dimensional magnetic field components in space.

[0015] Secondly, this application provides a method for measuring extremely weak magnetic field signals using the measuring device for extremely weak magnetic field signals described in the first aspect, comprising:

[0016] The magnetic field sensing mechanism in the measuring device for the extremely weak magnetic field signal is placed in the space to be measured; the magnetic field sensing mechanism includes at least a first vector sensor, a second vector sensor, a first non-magnetic turntable, and a second non-magnetic turntable; the space to be measured is located inside the magnetic shielding device; the light source, photodetector, encoder disk, drive motor, and analysis module in the measuring device for the extremely weak magnetic field signal are located outside the magnetic shielding device;

[0017] The measuring device for the extremely weak magnetic field signal is activated to measure the three-dimensional magnetic field components in the space to be measured.

[0018] According to the specific embodiments provided in this application, this application has the following technical effects:

[0019] This application provides a device and method for measuring extremely weak magnetic field signals. By setting a first vector sensor on a first non-magnetic turntable and a second vector sensor on a second non-magnetic turntable, and arranging the first and second non-magnetic turntables in a mutually perpendicular configuration (the first and second support rods are perpendicular to each other), the first and second non-magnetic turntables drive the first and second vector sensors to rotate synchronously, thereby obtaining magnetic field vector modulation signals on two rotating planes, namely the first magnetic field modulation signal and the second magnetic field modulation signal. Then, by using a light source, a photodetector, and a synchronously rotating encoder disk to obtain an electrical pulse reference signal with the same frequency as the magnetic field vector modulation signal, the modulation signal is demodulated and filtered to obtain a bias-free background magnetic field signal, namely the three-dimensional magnetic field component, thus realizing the accurate measurement of the background magnetic field in an extremely weak magnetic environment. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram of a measuring device for extremely weak magnetic field signals provided in an embodiment of this application;

[0022] Figure 2 This is a schematic diagram showing the placement of the encoder disk and vector sensor according to an embodiment of this application;

[0023] Figure 3 A schematic diagram of a measuring device for extremely weak magnetic field signals based on wired communication, provided in an embodiment of this application;

[0024] Figure 4A schematic diagram of a device for measuring extremely weak magnetic field signals based on wireless communication, provided as an embodiment of this application;

[0025] Figure 5 This is a flowchart illustrating a method for measuring extremely weak magnetic field signals according to an embodiment of this application.

[0026] Reference numerals: 1-Magnetic shielding device, 2-First vector sensor, 3-First non-magnetic turntable, 4-First support rod, 5-First gear, 6-Second gear, 7-Second support rod, 8-Second vector sensor, 9-Second non-magnetic turntable, 10-Light source, 11-Encoder disk, 12-Photodetector, 13-Drive motor, 14-Analysis module, 15-Frame, 16-First conductive slip ring, 17-Second conductive slip ring, 18-Third conductive slip ring, 19-Power supply, 20-Fourth conductive slip ring, 21-First conversion circuit, 22-First non-magnetic antenna, 23-Second conversion circuit, 24-Second non-magnetic antenna, 25-Third conversion circuit, 26-Third non-magnetic antenna, 27-Fourth conversion circuit, 28-Fourth non-magnetic antenna, 29-First battery assembly, 30-Second battery assembly. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Example 1

[0030] In one exemplary embodiment, such as Figure 1 As shown, a device for measuring extremely weak magnetic field signals is provided, including: a first vector sensor 2, a second vector sensor 8, a first non-magnetic turntable 3, a second non-magnetic turntable 9, a first support rod 4, a second support rod 7, a light source 10, a photodetector 12, an encoder disk 11, a drive motor 13, an analysis module 14, and a frame 15.

[0031] The first vector sensor 2 is disposed in the center area of ​​the surface of the first non-magnetic turntable 3; the center area of ​​the bottom surface of the first non-magnetic turntable 3 is vertically connected to one end of the first support rod 4; the other end of the first support rod 4 passes vertically through the center of the encoder disk 11 and is connected to the shaft of the drive motor 13; the second vector sensor 8 is disposed in the center area of ​​the surface of the second non-magnetic turntable 9; the center area of ​​the bottom surface of the second non-magnetic turntable 9 is vertically connected to one end of the second support rod 7; the other end of the second support rod 7 is connected to the frame 15 through a bearing; the drive motor 13 is disposed below the frame 15; the bearing is positioned with its axis perpendicular to the axis of the drive motor 13. The components are arranged above the frame 15; a first gear 5 is mounted on the first support rod 4; a second gear 6 is mounted on the second support rod 7; the first gear 5 and the second gear 6 have the same number of teeth; the first support rod 4 and the second support rod 7 are linked by the first gear 5 and the second gear 6; half of the encoder disk 11 is a light-transmitting area, and the other half of the encoder disk 11 is an opaque area; the light source 10 and the photodetector 12 are respectively arranged on both sides of the encoder disk 11 and do not rotate with the encoder disk 11; the light beam emitted by the light source 10 can only illuminate the photosensitive surface of the photodetector 12 through the light-transmitting area of ​​the encoder disk 11; the light source 10, the photodetector 12 and the analysis module 14 are arranged below the frame.

[0032] When the drive motor 13 drives the first support rod 4 to rotate, the encoder disk 11 and the second support rod 7 rotate synchronously with the first support rod 4, the first non-magnetic turntable 3 and the second non-magnetic turntable 9 rotate synchronously with the first support rod 4 and the second support rod 7, and the first vector sensor 2 and the second vector sensor 8 rotate synchronously with the first non-magnetic turntable 3 and the second non-magnetic turntable 9.

[0033] While rotating, the first vector sensor 2 outputs a first magnetic field modulation signal to the analysis module 14.

[0034] While rotating, the second vector sensor 8 outputs a second magnetic field modulation signal to the analysis module 14.

[0035] The photodetector 12 is used to output an electrical pulse reference signal to the analysis module 14 while the encoder disk 11 rotates. In this document, the electrical pulse reference signal is also referred to as the reference signal.

[0036] The analysis module 14 is used to analyze and process the received first magnetic field modulation signal, second magnetic field modulation signal and electric pulse reference signal to determine the three-dimensional magnetic field components in space.

[0037] Both the first support rod 4 and the second support rod 7 are non-magnetic support rods, so they are collectively referred to as non-magnetic support rods. Both the first gear 5 and the second gear 6 are non-magnetic gears, so they are collectively referred to as non-magnetic gears. The first vector sensor and the second vector sensor are also collectively referred to as vector sensors.

[0038] In this application, the object of measurement is the background magnetic field of a magnetically shielded environment, such as the background magnetic field of the space inside a magnetic shield. The encoder disk has light-transmitting and light-blocking areas. As the encoder disk rotates with the non-magnetic support rod, it cuts the light beam into light pulses. The photodetector converts the light pulses into current pulse signals (i.e., electrical pulse reference signals).

[0039] As an optional implementation, in analyzing and processing the received first magnetic field modulation signal, second magnetic field modulation signal, and electrical pulse reference signal to determine the three-dimensional magnetic field components in space, the operations performed by the analysis module 14 specifically include:

[0040] S1: Generate in-phase and quadrature signals with the same frequency and phase as the electrical pulse reference signal.

[0041] S2: Demodulate the first magnetic field modulation signal based on the in-phase signal and the quadrature signal to obtain the first initial two-dimensional magnetic field component.

[0042] S3: Demodulate the second magnetic field modulation signal based on the in-phase signal and the quadrature signal to obtain the second initial two-dimensional magnetic field component.

[0043] S4: Use a low-pass filter to filter the first initial two-dimensional magnetic field component and the second initial two-dimensional magnetic field component to obtain the first two-dimensional magnetic field component and the second two-dimensional magnetic field component.

[0044] S5: Determine the three-dimensional magnetic field components in space based on the first two-dimensional magnetic field components and the second two-dimensional magnetic field components.

[0045] The signal modulation / demodulation process is explained further below:

[0046] Because vector sensors exhibit output bias in practical applications (an inherent bias of the instrument itself, which can arise from various causes), direct measurement leads to a decrease in the accuracy of the background magnetic field. To address this issue, this application introduces a modulation signal by rotating the vector sensor to effectively separate the bias signal from the background magnetic field signal. The specific principle is as follows:

[0047] When the drive motor starts and rotates the non-magnetic support rod (and the non-magnetic gear), the two non-magnetic turntables rotate synchronously. The turntables rotate at a constant angular frequency. Rotation causes the sensitive direction of the magnetic sensor (vector sensor) to change continuously. This rotational motion is equivalent to applying a modulated signal of known frequency and amplitude to the background magnetic field of the plane in which it is located. Specifically, the total magnetic field of the plane containing the two rotational movements... and The projection in the sensor coordinate system changes with time, and its expression can be given as:

[0048] (1);

[0049] (2);

[0050] in, This represents the total magnetic field of the plane containing the first non-magnetic turntable; This represents the total magnetic field in the plane containing the second non-magnetic turntable; , , These are the environmental magnetic fields in three directions; among them, , These are the environmental magnetic field components in two perpendicular directions within the plane where the first non-magnetic turntable is located; , These are the environmental magnetic field components in two perpendicular directions within the plane where the second non-magnetic turntable is located; This represents the angular frequency of the rotational motion of the vector sensor. Indicates phase.

[0051] Vector sensor output signal Includes modulated background magnetic field signal and the bias signal of the sensor , The expression is:

[0052] (3);

[0053] in, Let be the sensitivity coefficient of the vector sensor. For simplicity, we use here. To uniformly represent the output signal of the first vector sensor and the output signal of the first vector sensor , Similarly.

[0054] In some implementations, in order to accurately extract the magnetic field component in the modulation signal while suppressing the bias signal and other interference signals, a lock-in amplifier can be used as an analysis module for detection and demodulation.

[0055] Figure 2 An example of the placement of the encoder disk and the vector sensor.

[0056] When the two non-magnetic support rods rotate, the encoder disk 11 rotates synchronously with the two vector sensors. When the area between the light source 10 and the photodetector 12 is a transparent region of the encoder disk 11, the pulse signal generated by the photodetector 12 is high-level; when the area between the light source 10 and the photodetector 12 is an opaque region of the encoder disk 11, the pulse signal generated by the photodetector 12 is low-level. The generated pulse signal is fed into the lock-in amplifier (analysis module 14) as a reference signal. As shown in Formula 4. Figure 2 As shown, the magnetic field modulation signal and the reference signal in the y-direction The high-level in-phase signal and the magnetic field modulation signal in the x-direction are in phase with the reference signal. The high-level phase difference is 90°.

[0057] (4);

[0058] In formula (4), It is a positive integer.

[0059] like Figure 2 As shown, when t=0 (i.e. the initial moment), the light from the light source passes through the middle position of the photosensitive area of ​​the encoder disk. That is, at the beginning, the light from the vector sensor and the light source both pass through the radius of the middle of the photosensitive area (transparent area). Therefore, the range of the high level in formula (4) is -90°~90°, and the corresponding low level is 90°~270°. Figure 2 In The angle of rotation of the encoder disk is equal to the angle of rotation of the drive motor. Since they rotate simultaneously, their phase and frequency are the same. Figure 2 In the initial moment, the y-axis coincides with the dashed line.

[0060] Figure 2 In the diagram, the black area represents the non-photosensitive area (i.e., the opaque area). Figure 2 This demonstrates how a vector sensor is placed on a non-magnetic turntable (i.e., the initial orientation of the vector sensor). The first non-magnetic turntable and the encoder disk are on the same axis, so the encoder disk is used to illustrate its placement orientation, which is also the measurement orientation of the first vector sensor. Figure 2 The direction of the light source (with the length direction in the middle) is perpendicular to the boundary line between the light-transmitting and opaque areas of the encoder disk, and the initial position of the light source is... Figure 2 The part of the dashed line that is not blocked by the vector sensor allows light to pass through the encoder disk and be detected by the photodetector (or phototrigger), thus generating an electrical pulse signal in the form of formula (4).

[0061] The second vector sensor is placed in the same orientation to ensure that the magnetic field modulation signal output by the second vector sensor is also consistent with the reference signal. The high level is in phase with the phase, which, for ease of understanding, can be... Figure 2The x-axis is replaced with the z-axis. The y-axis of the plane containing the second non-magnetic turntable is parallel to the y-axis of the plane containing the first non-magnetic turntable.

[0062] The lock-in amplifier receives a reference signal from the photodetector 12. Generates a signal with the same frequency as the reference signal. and phase In-phase signal and orthogonal signals :

[0063] (5);

[0064] (6);

[0065] The lock-in amplifier outputs the signal from the first vector sensor. Demodulate the in-phase signal and the quadrature signal respectively to obtain the in-phase component. and orthogonal components Then, a low-pass filter is used to filter out high-frequency components, retaining the DC component, to obtain an estimate of the magnetic field component. and :

[0066] (7);

[0067] (8);

[0068] in, and Corresponding to the background magnetic field and Quantity; This indicates a low-pass filter.

[0069] The output signal of the second vector sensor can be extracted through a similar demodulation process to obtain... The components, that is, the final three-dimensional magnetic field components.

[0070] As an optional implementation, when the first vector sensor 2 outputs a first magnetic field modulation signal to the analysis module 14 via wired communication, the measuring device further includes a first conductive slip ring 16, a first cable, and a second cable; the first conductive slip ring 16 is arranged around the first support rod 4; the first conductive slip ring 16 does not rotate with the first support rod 4; one end of the first cable is connected to the signal output terminal of the first vector sensor 2; the other end of the first cable is slidably connected to the first conductive slip ring 16; one end of the second cable is fixedly connected to the first conductive slip ring 16; the other end of the second cable is connected to the first signal input terminal of the analysis module 14, see [reference]. Figure 3 .

[0071] When the second vector sensor 8 outputs a second magnetic field modulation signal to the analysis module 14 via wired communication, the measuring device further includes a second conductive slip ring 17, a third cable, and a fourth cable; the second conductive slip ring 17 is arranged around the second support rod 7; the second conductive slip ring 17 does not rotate with the second support rod 7; one end of the third cable is connected to the signal output terminal of the second vector sensor 8; the other end of the third cable is slidably connected to the second conductive slip ring 17; one end of the fourth cable is fixedly connected to the second conductive slip ring 17; the other end of the fourth cable is connected to the second signal input terminal of the analysis module 14.

[0072] When calibrating or measuring the near-zero magnetic environment in a magnetic shielding device, a non-magnetic turntable and a non-magnetic gear are placed inside the magnetic shielding device. A non-magnetic support rod and part of the frame pass through the through-holes in the shielding device. The first conductive slip ring and drive motor are placed outside the shielding device. See [link to relevant documentation]. Figure 3 .

[0073] As an optional implementation, when the first vector sensor 2 outputs a first magnetic field modulation signal to the analysis module 14 via wired communication, the measuring device further includes a third conductive slip ring 18, a fifth cable, a sixth cable, and a power supply; the third conductive slip ring 18 is arranged around the first support rod 4; the third conductive slip ring 18 does not rotate with the first support rod 4; one end of the fifth cable is connected to the power supply terminal of the first vector sensor 2; the other end of the fifth cable is slidably connected to the third conductive slip ring 18; one end of the sixth cable is fixedly connected to the third conductive slip ring 18; the other end of the sixth cable is connected to the output terminal of the power supply 19.

[0074] When the second vector sensor 8 outputs a second magnetic field modulation signal to the analysis module 14 via wired communication, the measuring device further includes a fourth conductive slip ring 20, a seventh cable, an eighth cable, and a power supply 19; the fourth conductive slip ring 20 is arranged around the second support rod 7; the fourth conductive slip ring 20 does not rotate with the second support rod 7; one end of the seventh cable is connected to the power supply terminal of the second vector sensor 8; the other end of the seventh cable is slidably connected to the fourth conductive slip ring 20; one end of the eighth cable is fixedly connected to the fourth conductive slip ring 20; the other end of the eighth cable is connected to the output terminal of the power supply 19.

[0075] The first conductive slip ring 16, the second conductive slip ring 17, the third conductive slip ring 18, and the fourth conductive slip ring 20 can be fixed by connecting to the frame.

[0076] In this embodiment, the non-magnetic turntable is connected to the drive motor via a non-magnetic support rod. The non-magnetic turntable is used to fix the vector sensor and make it rotate, so as to modulate the background magnetic field.

[0077] The drive motor 13 drives the non-magnetic turntable and the non-magnetic gear to rotate. The non-magnetic gear is used to drive the secondary support rod (second support rod) to rotate, so as to realize the synchronous rotation of the two non-magnetic turntables. Its power supply line and signal line are connected through conductive slip rings to avoid the problem of cable tangling during rotation.

[0078] The non-magnetic support rod and the non-magnetic gear can be integrally milled and formed. During assembly, the shaft shoulder is inserted into the frame via a bearing and locked with a non-magnetic nut. Through the meshing of two identical digital gears, the first support rod transmits torque without backlash when it rotates, driving the second support rod to rotate synchronously and at the same speed.

[0079] When the non-magnetic turntable rotates, the background magnetic field in the magnetic shielding device will be modulated and presented in the output signal of the vector sensor. The synchronously rotating encoder disk will cause the photodetector to generate an electrical pulse reference signal (referred to as electrical pulse signal) that is phase-dependent with the modulated signal. The electrical pulse signal is fed into the lock-in amplifier as a reference signal for the phase of the demodulated signal. After demodulating and filtering the output signal, the magnetic field component of the background magnetic field in the magnetic shielding device on the turntable plane can be obtained.

[0080] As an optional implementation, when the first vector sensor 2 outputs a first magnetic field modulation signal to the analysis module 14 via wireless communication, the measuring device further includes a first conversion circuit 21, a first non-magnetic antenna 22, a second conversion circuit 23, and a second non-magnetic antenna 24.

[0081] The first conversion circuit 21 and the first non-magnetic antenna 22 are disposed on the surface of the first non-magnetic turntable 3; the signal input terminal of the first conversion circuit 21 is connected to the signal output terminal of the first vector sensor 2; the signal output terminal of the first conversion circuit 21 is connected to the first non-magnetic antenna 22; the first conversion circuit 21 is used to convert the electrical signal output by the first vector sensor 2 into a radio frequency signal and output it to the first non-magnetic antenna 22; the first non-magnetic antenna 22 is used to convert the radio frequency signal output by the first conversion circuit 21 into a wireless signal.

[0082] The signal output terminal of the second conversion circuit 23 is connected to the third signal input terminal of the analysis module 14; the signal input terminal of the second conversion circuit 23 is connected to the second non-magnetic antenna 24; the second non-magnetic antenna 24 is used to receive the wireless signal transmitted by the first non-magnetic antenna 22, and to convert the wireless signal transmitted by the first non-magnetic antenna 22 into a radio frequency signal and output it to the second conversion circuit 23; the second conversion circuit 23 is used to convert the radio frequency signal output by the second non-magnetic antenna 24 into a digital signal and output it to the analysis module 14, see [link to relevant documentation]. Figure 4 .

[0083] As an optional implementation, when the second vector sensor 8 outputs a second magnetic field modulation signal to the analysis module 14 via wireless communication, the measuring device further includes a third conversion circuit 25, a third non-magnetic antenna 26, a fourth conversion circuit 27, and a fourth non-magnetic antenna 28.

[0084] The third conversion circuit 25 and the third non-magnetic antenna 26 are disposed on the surface of the second non-magnetic turntable 9; the signal input terminal of the third conversion circuit 25 is connected to the signal output terminal of the second vector sensor 8; the signal output terminal of the third conversion circuit 25 is connected to the third non-magnetic antenna 26; the third conversion circuit 25 is used to convert the electrical signal output by the second vector sensor 8 into a radio frequency signal and output it to the third non-magnetic antenna 26; the third non-magnetic antenna 26 is used to convert the radio frequency signal output by the third conversion circuit 25 into a wireless signal.

[0085] The signal output terminal of the fourth conversion circuit 27 is connected to the fourth signal input terminal of the analysis module 14; the signal input terminal of the fourth conversion circuit 27 is connected to the fourth non-magnetic antenna 28; the fourth non-magnetic antenna 28 is used to receive the wireless signal transmitted by the third non-magnetic antenna 26, and to convert the wireless signal transmitted by the third non-magnetic antenna 26 into a radio frequency signal and output it to the fourth conversion circuit 27; the fourth conversion circuit 27 is used to convert the radio frequency signal output by the fourth non-magnetic antenna 28 into a digital signal and output it to the analysis module 14.

[0086] In this paper, the first non-magnetic antenna 22, the second non-magnetic antenna 24, the third non-magnetic antenna 26, and the fourth non-magnetic antenna 28 are collectively referred to as non-magnetic antennas.

[0087] In some embodiments, the second conversion circuit 23 and the fourth conversion circuit 27 are the same conversion circuit, which can be connected to the third signal input terminal or the fourth signal input terminal of the analysis module, and the second non-magnetic antenna 24 and the fourth non-magnetic antenna 28 are the same non-magnetic antenna.

[0088] As an optional implementation, when the first vector sensor 2 outputs a first magnetic field modulation signal to the analysis module 14 via wireless communication, the measuring device further includes a first battery assembly 29; the first battery assembly 29 is disposed on the surface of the first non-magnetic turntable 3; the power output terminal of the first battery assembly 29 is connected to the power supply terminal of the first vector sensor 2.

[0089] As an optional implementation, when the second vector sensor 8 outputs a second magnetic field modulation signal to the analysis module 14 via wireless communication, the measuring device further includes a second battery assembly 30; the second battery assembly 30 is disposed on the surface of the second non-magnetic turntable 9; the power output terminal of the second battery assembly 30 is connected to the power supply terminal of the second vector sensor 8.

[0090] like Figure 4 As shown, wireless communication is used instead of conductive slip rings to lead out power and signal lines. A vector sensor, sensor power supply (i.e., the first or second battery assembly), conversion circuit, and non-magnetic antenna are fixed on the non-magnetic turntable. The output signal of the vector sensor is converted into an radio frequency signal by the conversion circuit and then transmitted by the non-magnetic antenna. The signal can be received by a non-magnetic antenna (the second or fourth non-magnetic antenna) fixed on the through hole of the shielding device and then transmitted to the conversion circuit outside the shielding device. The conversion circuit converts the radio frequency signal into a digital signal and sends it to the lock-in amplifier. After demodulation and filtering of the digital signal, the magnetic field component of the background magnetic field in the magnetic shielding device on the turntable plane can be obtained. The second or fourth non-magnetic antenna can also be fixed on the frame and set outside the magnetic shielding device, such as at the bottom of the frame.

[0091] Figure 1 , Figure 3 and Figure 4 In the diagram, dashed lines are used to represent cables.

[0092] Example 2

[0093] Based on the same inventive concept, this application also provides a method for measuring extremely weak magnetic field signals using the aforementioned measuring device. The solution provided by this method is similar to the implementation described above. Therefore, the specific limitations of one or more embodiments of the method for measuring extremely weak magnetic field signals provided below can be found in the limitations of the measuring device for extremely weak magnetic field signals described above, and will not be repeated here.

[0094] In one exemplary embodiment, such as Figure 5 As shown, a method for measuring extremely weak magnetic field signals is provided, including:

[0095] Step 101: Place the magnetic field sensing mechanism in the measuring device for the extremely weak magnetic field signal into the space to be measured; the magnetic field sensing mechanism includes at least a first vector sensor 2, a second vector sensor 8, a first non-magnetic turntable 3, and a second non-magnetic turntable 9; the space to be measured is located inside the magnetic shielding device 1; the light source 10, photodetector 12, encoder disk 11, drive motor 13, and analysis module 14 in the measuring device for the extremely weak magnetic field signal are located outside the magnetic shielding device 1.

[0096] Step 102: Start the measuring device for the extremely weak magnetic field signal to measure the three-dimensional magnetic field components in the space to be measured.

[0097] The functions of some of the components mentioned in this article are further explained below.

[0098] 1) Magnetic shielding device: Provides a near-zero magnetic environment, shields against magnetic field interference from the external environment, and ensures that only extremely weak internal magnetic field signals are detected during the measurement process. It is usually made of highly permeable magnetic materials such as nickel-iron alloys or superconducting materials to effectively shield external magnetic fields.

[0099] 2) Non-magnetic support rod: Connects the non-magnetic turntable to the drive motor, supporting the entire rotating system and ensuring structural stability and non-magnetic characteristics. It is made of non-magnetic materials such as titanium alloy, stainless steel, or plastic to avoid interference with the magnetic field.

[0100] 3) Drive motor: Provides power to rotate the non-magnetic turntable and non-magnetic gear. The drive motor must have precise speed control capability to ensure the constant rotation speed of the turntable. The speed stability directly affects the frequency and accuracy of the modulation signal.

[0101] 4) Non-magnetic turntable: It carries a vector magnetic sensor and modulates the magnetic field by rotating. It is made of non-magnetic materials such as aluminum alloy, titanium alloy or high-strength plastic to ensure that no additional magnetic field interference is introduced during rotation.

[0102] 5) Non-magnetic gears: Through transmission, the secondary support rod (secondary support rod) rotates synchronously, ensuring the synchronous movement of the two non-magnetic turntables. They are made of non-magnetic materials such as titanium alloys or special plastics, and the gear design ensures precise meshing to reduce mechanical friction and wear.

[0103] 6) Conductive slip ring: During the rotation of the turntable, it maintains a stable connection between the power supply and signal lines of the vector sensor and avoids cable tangling.

[0104] 7) Non-magnetic antenna: The vector sensor output signal is converted into a radio frequency signal by a conversion circuit and transmitted. This signal is received by a non-magnetic antenna fixed to a through-hole in the magnetic shielding device. The radio frequency signal is then converted into a digital signal by a circuit outside the magnetic shielding device and transmitted to a lock-in amplifier. This replaces the structure of a conductive slip ring fixing the power supply and signal lines, avoiding mechanical wear and complex wiring problems caused by wire connections, and improving system flexibility.

[0105] 8) Vector Sensor: Detects changes in the magnetic field within the magnetic shielding device and outputs an electrical signal related to the magnetic field composition. The coefficients of the vector sensor need to be calibrated, and bias errors are removed through modulation and demodulation to obtain the magnetic field component of the background magnetic field on the turntable plane.

[0106] 9) Lock-in amplifier: Synchronously demodulates and filters the output signal of the vector sensor to extract the magnetic field component corresponding to the rotation frequency. By demodulating the sensor output signal, the lock-in amplifier can effectively suppress noise of unrelated frequencies, improve the signal-to-noise ratio, and ensure the accurate extraction of the magnetic field component.

[0107] In this application, the background magnetic field in an extremely weak magnetic environment can be accurately measured using wired or wireless communication. A magnetic field vector modulation signal is obtained through a non-magnetic rotating disk vector sensor. This modulation signal is then demodulated and filtered by a lock-in amplifier to obtain a bias-free background magnetic field signal.

[0108] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0109] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A measuring device for extremely weak magnetic field signals, characterized in that, include: The system comprises a first vector sensor, a second vector sensor, a first non-magnetic turntable, a second non-magnetic turntable, a first support rod, a second support rod, a light source, a photodetector, an encoder disk, a drive motor, an analysis module, and a frame. The system comprises the following components: a first vector sensor located at the center of the surface of a first non-magnetic turntable; a vertical connection between the center of the bottom surface of the first non-magnetic turntable and one end of a first support rod; the other end of the first support rod passing vertically through the center of the encoder disk and connected to the shaft of a drive motor; a second vector sensor located at the center of the surface of a second non-magnetic turntable; a vertical connection between the center of the bottom surface of the second non-magnetic turntable and one end of a second support rod; the other end of the second support rod connected to the frame via a bearing; a drive motor located below the frame; a bearing located above the frame with its axis perpendicular to the drive motor's axis; a first gear on the first support rod; a second gear on the second support rod; both gears having the same number of teeth; and linkage between the first and second support rods via the first and second gears; one half of the encoder disk being a light-transmitting area and the other half being an opaque area; a light source and a photodetector located on opposite sides of the encoder disk, and not rotating with the encoder disk; a beam of light emitted by the light source only illuminates the photosensitive surface of the photodetector through the light-transmitting area of ​​the encoder disk; and a light source, photodetector, and analysis module located below the frame. When the drive motor drives the first support rod to rotate, the encoder disk and the second support rod rotate synchronously with the first support rod, the first non-magnetic turntable and the second non-magnetic turntable rotate synchronously with the first support rod and the second support rod, and the first vector sensor and the second vector sensor rotate synchronously with the first non-magnetic turntable and the second non-magnetic turntable, respectively. While rotating, the first vector sensor outputs a first magnetic field modulation signal to the analysis module; While rotating, the second vector sensor outputs a second magnetic field modulation signal to the analysis module; The photodetector is used to output an electrical pulse reference signal to the analysis module while the encoder disk rotates. The analysis module is used to analyze and process the received first magnetic field modulation signal, second magnetic field modulation signal and electric pulse reference signal to determine the three-dimensional magnetic field components in space.

2. The measuring device for extremely weak magnetic field signals according to claim 1, characterized in that, In analyzing and processing the received first magnetic field modulation signal, second magnetic field modulation signal, and electrical pulse reference signal to determine the three-dimensional magnetic field components in space, the operations performed by the analysis module specifically include: Generate in-phase and quadrature signals with the same frequency and phase as the electrical pulse reference signal; The first magnetic field modulation signal is demodulated based on the in-phase signal and the quadrature signal to obtain the first initial two-dimensional magnetic field component; The second magnetic field modulation signal is demodulated based on the in-phase signal and the quadrature signal to obtain the second initial two-dimensional magnetic field component; The first and second initial two-dimensional magnetic field components are filtered by a low-pass filter to obtain the first and second two-dimensional magnetic field components. The three-dimensional magnetic field components in space are determined based on the first two-dimensional magnetic field components and the second two-dimensional magnetic field components.

3. The measuring device for extremely weak magnetic field signals according to claim 1, characterized in that, When the first vector sensor outputs a first magnetic field modulation signal to the analysis module via wired communication, the measuring device further includes a first conductive slip ring, a first cable, and a second cable; the first conductive slip ring is arranged around a first support rod; the first conductive slip ring does not rotate with the first support rod; one end of the first cable is connected to the signal output terminal of the first vector sensor; the other end of the first cable is slidably connected to the first conductive slip ring; one end of the second cable is fixedly connected to the first conductive slip ring; the other end of the second cable is connected to the first signal input terminal of the analysis module. When the second vector sensor outputs a second magnetic field modulation signal to the analysis module via wired communication, the measuring device further includes a second conductive slip ring, a third cable, and a fourth cable; the second conductive slip ring is arranged around the second support rod; the second conductive slip ring does not rotate with the second support rod; one end of the third cable is connected to the signal output terminal of the second vector sensor; the other end of the third cable is slidably connected to the second conductive slip ring; one end of the fourth cable is fixedly connected to the second conductive slip ring; the other end of the fourth cable is connected to the second signal input terminal of the analysis module.

4. The measuring device for extremely weak magnetic field signals according to claim 3, characterized in that, When the first vector sensor outputs a first magnetic field modulation signal to the analysis module via wired communication, the measuring device further includes a third conductive slip ring, a fifth cable, a sixth cable, and a power supply; the third conductive slip ring is arranged around the first support rod; the third conductive slip ring does not rotate with the first support rod; one end of the fifth cable is connected to the power supply terminal of the first vector sensor; the other end of the fifth cable is slidably connected to the third conductive slip ring; one end of the sixth cable is fixedly connected to the third conductive slip ring; the other end of the sixth cable is connected to the output terminal of the power supply. When the second vector sensor outputs a second magnetic field modulation signal to the analysis module via wired communication, the measuring device further includes a fourth conductive slip ring, a seventh cable, an eighth cable, and a power supply; the fourth conductive slip ring is arranged around the second support rod; the fourth conductive slip ring does not rotate with the second support rod; one end of the seventh cable is connected to the power supply terminal of the second vector sensor; the other end of the seventh cable is slidably connected to the fourth conductive slip ring; one end of the eighth cable is fixedly connected to the fourth conductive slip ring; the other end of the eighth cable is connected to the output terminal of the power supply.

5. The measuring device for extremely weak magnetic field signals according to claim 1, characterized in that, When the first vector sensor outputs a first magnetic field modulation signal to the analysis module via wireless communication, the measuring device further includes a first conversion circuit, a first non-magnetic antenna, a second conversion circuit, and a second non-magnetic antenna. The first conversion circuit and the first non-magnetic antenna are disposed on the surface of the first non-magnetic turntable; the signal input terminal of the first conversion circuit is connected to the signal output terminal of the first vector sensor; the signal output terminal of the first conversion circuit is connected to the first non-magnetic antenna; the first conversion circuit is used to convert the electrical signal output by the first vector sensor into a radio frequency signal and output it to the first non-magnetic antenna; the first non-magnetic antenna is used to convert the radio frequency signal output by the first conversion circuit into a wireless signal. The signal output terminal of the second conversion circuit is connected to the third signal input terminal of the analysis module; the signal input terminal of the second conversion circuit is connected to the second non-magnetic antenna; the second non-magnetic antenna is used to receive the wireless signal transmitted by the first non-magnetic antenna, and to convert the wireless signal transmitted by the first non-magnetic antenna into a radio frequency signal and output it to the second conversion circuit; the second conversion circuit is used to convert the radio frequency signal output by the second non-magnetic antenna into a digital signal and output it to the analysis module.

6. The measuring device for extremely weak magnetic field signals according to claim 1, characterized in that, When the second vector sensor outputs a second magnetic field modulation signal to the analysis module via wireless communication, the measuring device further includes a third conversion circuit, a third non-magnetic antenna, a fourth conversion circuit, and a fourth non-magnetic antenna. The third conversion circuit and the third non-magnetic antenna are disposed on the surface of the second non-magnetic turntable; the signal input terminal of the third conversion circuit is connected to the signal output terminal of the second vector sensor; the signal output terminal of the third conversion circuit is connected to the third non-magnetic antenna; the third conversion circuit is used to convert the electrical signal output by the second vector sensor into a radio frequency signal and output it to the third non-magnetic antenna; the third non-magnetic antenna is used to convert the radio frequency signal output by the third conversion circuit into a wireless signal. The signal output terminal of the fourth conversion circuit is connected to the fourth signal input terminal of the analysis module; the signal input terminal of the fourth conversion circuit is connected to the fourth non-magnetic antenna; the fourth non-magnetic antenna is used to receive the wireless signal transmitted by the third non-magnetic antenna, and to convert the wireless signal transmitted by the third non-magnetic antenna into a radio frequency signal and output it to the fourth conversion circuit; the fourth conversion circuit is used to convert the radio frequency signal output by the fourth non-magnetic antenna into a digital signal and output it to the analysis module.

7. The measuring device for extremely weak magnetic field signals according to claim 5, characterized in that, When the first vector sensor outputs a first magnetic field modulation signal to the analysis module via wireless communication, the measuring device further includes a first battery assembly; the first battery assembly is disposed on the surface of the first non-magnetic turntable; the power output terminal of the first battery assembly is connected to the power supply terminal of the first vector sensor.

8. The measuring device for extremely weak magnetic field signals according to claim 6, characterized in that, When the second vector sensor outputs a second magnetic field modulation signal to the analysis module via wireless communication, it also includes a second battery assembly; the second battery assembly is disposed on the surface of the second non-magnetic turntable; the power output terminal of the second battery assembly is connected to the power supply terminal of the second vector sensor.

9. The measuring device for extremely weak magnetic field signals according to claim 1, characterized in that, Both the first support rod and the second support rod are non-magnetic support rods; both the first gear and the second gear are non-magnetic gears.

10. A method for measuring extremely weak magnetic field signals using the measuring device for extremely weak magnetic field signals according to any one of claims 1-9, characterized in that, include: Place the magnetic field sensing mechanism in the measuring device for the extremely weak magnetic field signal into the space to be measured; The magnetic field sensing mechanism includes at least a first vector sensor, a second vector sensor, a first non-magnetic turntable, and a second non-magnetic turntable; the space to be measured is located inside the magnetic shielding device; the light source, photodetector, encoder disk, drive motor, and analysis module in the measuring device for the extremely weak magnetic field signal are located outside the magnetic shielding device. The measuring device for the extremely weak magnetic field signal is activated to measure the three-dimensional magnetic field components in the space to be measured.

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