Device and method for measuring extremely low magnetic field signal

Abstract

The invention discloses a device and a method for measuring an extremely low magnetic field signal, and relates to the technical field of weak magnetic field measurement, and the device comprises a first vector sensor and a second vector sensor which are respectively arranged in the central areas of a first non-magnetic turntable and a second non-magnetic turntable, and the first non-magnetic turntable and the second non-magnetic turntable are respectively and vertically connected with a first support rod and a second support rod; the first supporting rod and the second supporting rod are vertically arranged and are linked through the first gear and the second gear, and the first supporting rod is further provided with a coding disc; when the driving motor drives the first supporting rod to rotate, the first vector sensor and the second vector sensor synchronously rotate and respectively output first and second magnetic field modulation signals; meanwhile, the coding disc synchronously rotates, so that the photoelectric detector outputs an electric pulse reference signal; the analysis module analyzes and processes the received first magnetic field modulation signal, the received second magnetic field modulation signal and the reference signal so as to determine a three-dimensional magnetic field component in the space. According to the invention, accurate measurement of the background magnetic field in the extremely weak magnetic environment is realized.

Description

Technical Field

[0001] The present application relates to the technical field of weak magnetic field measurement, and in particular to a device and method for measuring extremely weak magnetic field signals. Background Art

[0002] Weak magnetic fields play a vital role in modern science, technology, and research. Although their intensity is extremely low, they are ubiquitous in nature and in life. The precise detection and analysis of these weak magnetic fields not only helps deepen our understanding of the magnetic properties of matter, but also provides a solid foundation for the development of sensitive sensors, the advancement of information technology, and the optimization of environmental monitoring methods. At the same time, progress in this field is creating new opportunities for clinical medical research. Magnetoencephalography (MEG) is an imaging method that uses extremely weak human biomagnetic signals to capture magnetic field changes generated by the discharge of brain neurons. It can measure brain magnetism with millisecond-level time resolution and extremely high sensitivity, thereby diagnosing diseases non-invasively. Extremely weak magnetic field measurements not only provide a unique perspective for the early diagnosis and intervention of neurological diseases, but also lay the foundation for further revealing the relationship between brain function and structure.

[0003] When measuring extremely weak magnetic fields, external magnetic interference can directly affect the results. Therefore, magnetic shielding devices are necessary to isolate stray magnetic fields from the environment. Magnetic shielding devices are typically made of highly permeable materials and can provide a measurement environment in the nanoT to picoT range. Effective magnetic shielding enables researchers to obtain more accurate and reliable magnetic field data, ensuring the accuracy of experimental results.

[0004] Currently, there is no mature method for measuring absolute near-zero magnetic fields. Existing technologies, in particular, cannot provide an effective solution for applications requiring precise measurement of the magnetic field vector. Traditional magnetic field measurement tools, such as fluxgate magnetometers, while offering high sensitivity, still face challenges with calibration in extremely weak magnetic environments. Therefore, new methods are urgently needed to accurately measure background magnetic fields in these 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 achieve accurate measurement of the background magnetic field in an extremely weak magnetic environment.

[0006] To achieve the above objectives, this application provides the following solutions: In a first aspect, the present application provides a device for measuring extremely weak magnetic field signals, comprising: 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 encoding disk, a drive motor, an analysis module, and a frame; The first vector sensor is arranged at the center of the disk surface of the first non-magnetic turntable; the center of the bottom surface of the first non-magnetic turntable is connected to one end of the first support rod in a vertical manner; the other end of the first support rod passes through the center of the encoder disk in a vertical manner and is connected to the rotating shaft of the drive motor; the second vector sensor is arranged at the center of the disk surface of the second non-magnetic turntable; the center of the bottom surface of the second non-magnetic turntable is connected to one end of the second support rod in a vertical manner; the other end of the second support rod is connected to the frame via a bearing; the drive motor is arranged at the bottom of the frame; the bearing is arranged at the top of the frame with its axis perpendicular to the axis of the drive motor; a first gear is arranged on the first support rod; a second gear is arranged on the second support rod; the first gear and the second gear have the same number of teeth; the first support rod and the second support rod are linked by the first gear and the second gear; half of the encoder disk is a light-transmitting area, and the other half is a light-opaque area; the light source and the photodetector are arranged on both sides of the encoder disk and do not rotate with the encoder disk; the light beam emitted by the light source can only pass through the light-transmitting area of ​​the encoder disk to illuminate the photosensitive surface of the photodetector; the light source, the photodetector and the analysis module are arranged at the bottom of the frame; When the driving motor drives the first support rod to rotate, the encoding disk and the second support rod rotate synchronously with the first support rod respectively, the first non-magnetic turntable and the second non-magnetic turntable rotate synchronously with the first support rod and the second support rod respectively, 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; 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 while rotating; The photoelectric detector is used to output an electric pulse reference signal to the analysis module while the encoding disk rotates; The analysis module is used to analyze and process the received first magnetic field modulation signal, the second magnetic field modulation signal and the electric pulse reference signal to determine the three-dimensional magnetic field components in space.

[0007] In a second aspect, the present application provides a method for measuring an extremely weak magnetic field signal using the extremely weak magnetic field signal measuring device described in the first aspect, comprising: The magnetic field sensing mechanism in the extremely weak magnetic field signal measuring device is placed in a 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 a magnetic shielding device; and the light source, photodetector, encoder, drive motor, and analysis module in the extremely weak magnetic field signal measuring device are located outside the magnetic shielding device; The device for measuring the extremely weak magnetic field signal is started to measure and obtain the three-dimensional magnetic field components in the space to be measured.

[0008] According to the specific embodiments provided in this application, this application has the following technical effects: The present application provides a device and method for measuring extremely weak magnetic field signals, by arranging a first vector sensor on a first non-magnetic turntable and a second vector sensor on a second non-magnetic turntable, and making the first non-magnetic turntable and the second non-magnetic turntable perpendicular to each other (the first support rod and the second support rod are perpendicular to each other), so that the first non-magnetic turntable and the second non-magnetic turntable drive the first vector sensor and the second vector sensor to rotate synchronously, so as to obtain 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 utilizing a light source, a photodetector and a synchronously rotating encoder disk, an electrical pulse reference signal with the same frequency as the magnetic field vector modulation signal is obtained, and then the modulation signal is demodulated and filtered to obtain an unbiased background magnetic field signal, namely, a three-dimensional magnetic field component, thereby achieving accurate measurement of the background magnetic field in an extremely weak magnetic environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present application 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 application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0010] Figure 1 A schematic diagram of a device for measuring extremely weak magnetic field signals provided in one embodiment of the present application; Figure 2 A schematic diagram of the placement of the encoder disk and vector sensor provided in one embodiment of the present application; Figure 3 A schematic diagram of a device for measuring extremely weak magnetic field signals based on wired communication provided in one embodiment of the present application; Figure 4 A schematic diagram of a device for measuring extremely weak magnetic field signals based on wireless communication provided in one embodiment of the present application; Figure 5 A flowchart of a method for measuring an extremely weak magnetic field signal provided in one embodiment of the present application.

[0011] Figure 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 DESCRIPTION

[0012] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0013] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0014] Example 1 In an exemplary embodiment, 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 encoding disk 11, a drive motor 13, an analysis module 14 and a frame 15.

[0015] Among them, the first vector sensor 2 is arranged in the center area of ​​the disk surface of the first non-magnetic turntable 3; the center area of ​​the bottom surface of the first non-magnetic turntable 3 is connected to one end of the first support rod 4 in a vertical manner; the other end of the first support rod 4 passes through the center of the encoding disk 11 in a vertical manner and is connected to the rotating shaft of the drive motor 13; the second vector sensor 8 is arranged in the center area of ​​the disk surface of the second non-magnetic turntable 9; the center area of ​​the bottom surface of the second non-magnetic turntable 9 is connected to one end of the second support rod 7 in a vertical manner; the other end of the second support rod 7 is connected to the frame 15 through a bearing; the drive motor 13 is arranged in the lower part of the frame 15; the bearing is perpendicular to the axis of the drive motor 13 in a manner It is arranged above the frame 15; a first gear 5 is arranged on the first support rod 4; a second gear 6 is arranged 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 encoding disk 11 is a light-transmitting area, and the other half of the encoding disk 11 is a light-impermeable area; the light source 10 and the photodetector 12 are correspondingly arranged on both sides of the encoding disk 11, and do not rotate with the encoding disk 11; the light beam emitted by the light source 10 can only pass through the light-transmitting area of ​​the encoding disk 11 to illuminate the photosensitive surface of the photodetector 12; the light source 10, the photodetector 12 and the analysis module 14 are arranged below the frame.

[0016] When the drive motor 13 drives the first support rod 4 to rotate, the encoding disk 11 and the second support rod 7 respectively rotate synchronously with the first support rod 4, the first non-magnetic turntable 3 and the second non-magnetic turntable 9 respectively 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 respectively rotate synchronously with the first non-magnetic turntable 3 and the second non-magnetic turntable 9.

[0017] The first vector sensor 2 outputs a first magnetic field modulation signal to the analysis module 14 while rotating.

[0018] The second vector sensor 8 outputs a second magnetic field modulation signal to the analysis module 14 while rotating.

[0019] The photoelectric detector 12 is used to output an electric pulse reference signal to the analysis module 14 while the encoder disk 11 rotates. Herein, the electric pulse reference signal is also referred to as a reference signal.

[0020] The analysis module 14 is used to analyze and process the received first magnetic field modulation signal, the second magnetic field modulation signal and the electric pulse reference signal to determine the three-dimensional magnetic field components in space.

[0021] The first support rod 4 and the second support rod 7 are both non-magnetic support rods, and are therefore collectively referred to as non-magnetic support rods. The first gear 5 and the second gear 6 are both non-magnetic gears, and are therefore collectively referred to as non-magnetic gears. The first vector sensor and the second vector sensor are also collectively referred to as vector sensors.

[0022] In this application, the measurement target is the background magnetic field of a magnetically shielded environment, such as the background magnetic field within a magnetic shield. The encoder disk is divided into light-transmitting and light-impermeable areas. The encoder disk rotates with a non-magnetic support rod, dividing the light beam into light pulses. The photodetector converts the light pulses into current pulse signals (i.e., electrical pulse reference signals).

[0023] As an optional embodiment, in terms of analyzing and processing the received first magnetic field modulation signal, the second magnetic field modulation signal, and the electric pulse reference signal to determine the three-dimensional magnetic field components in space, the operations performed by the analysis module 14 specifically include: S1: Generate an in-phase signal and a quadrature signal having the same frequency and phase as the electrical pulse reference signal.

[0024] S2: Demodulate the first magnetic field modulation signal according to the in-phase signal and the quadrature signal to obtain a first initial two-dimensional magnetic field component.

[0025] S3: Demodulate the second magnetic field modulation signal according to the in-phase signal and the quadrature signal to obtain a second initial two-dimensional magnetic field component.

[0026] S4: Filter the first initial two-dimensional magnetic field component and the second initial two-dimensional magnetic field component using a low-pass filter to obtain a first two-dimensional magnetic field component and a second two-dimensional magnetic field component.

[0027] S5: Determine a three-dimensional magnetic field component in space according to the first two-dimensional magnetic field component and the second two-dimensional magnetic field component.

[0028] The following further explains the signal modulation / demodulation process: Because vector sensors have output bias in practical applications (inherent in the instrument itself, resulting from a variety of factors), direct measurement can reduce the accuracy of background magnetic fields. 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: When the drive motor starts to drive the non-magnetic support rod (and non-magnetic gear) to rotate, the two non-magnetic turntables rotate synchronously. Rotation causes the sensitive direction of the magnetic sensor (vector sensor) to change continuously. This rotational motion is equivalent to applying a modulation signal of known frequency and amplitude to the background magnetic field in the plane. Specifically, the total magnetic field in the plane of the two rotational motions is and The projection in the sensor coordinate system changes with time, and its expression can be expressed as: (1); (2); in, represents the total magnetic field in the plane where the first non-magnetic turntable is located; represents the total magnetic field in the plane where the second non-magnetic turntable is located; 、 、 are the environmental magnetic fields in three directions respectively; among them, 、 are respectively the ambient magnetic field components in two perpendicular directions in the plane where the first non-magnetic turntable is located; 、 are the ambient magnetic field components in two perpendicular directions in the plane where the second non-magnetic turntable is located; Indicates the angular frequency of the vector sensor's rotational motion; Indicates phase.

[0029] Vector sensor output signal Contains modulated background magnetic field signal and the sensor bias signal , The expression is: (3); in, is the sensitivity coefficient of the vector sensor. For simplicity, To uniformly represent the output signal of the first vector sensor and the first vector sensor output signal , Same thing.

[0030] In some implementations, to accurately extract the magnetic field component in the modulated signal while suppressing the bias signal and other interfering signals, a lock-in amplifier may be used as an analysis module for detection and demodulation.

[0031] Figure 2 An example of the placement of the encoder disk and vector sensor.

[0032] 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 transparent, the pulse signal generated by the photodetector 12 is high. When the area between the light source 10 and the photodetector 12 is opaque, the pulse signal generated by the photodetector 12 is low. The generated pulse signal is transmitted to 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 in the y direction is The high level is in phase, and the magnetic field modulation signal in the x direction is in phase with the reference signal. The high level phase difference is 90°.

[0033] (4); In formula (4), Is a positive integer.

[0034] like Figure 2 As shown in Figure 1, 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 in the middle of the photosensitive area (transparent area), so the range of the high level of 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 both rotate at the same time, the phase and frequency are the same. Figure 2 In the figure, at the initial moment, the y-axis coincides with the dotted line.

[0035] Figure 2 In the figure, the black area represents the non-light-sensitive area (i.e., the non-light-transmitting area). Figure 2 The figure shows how the vector sensor is placed on the non-magnetic turntable (i.e. the initial direction 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 direction. Even if the measurement direction of the first vector sensor is ( Figure 2 The initial position of the light source is the same as the direction perpendicular to the boundary line between the light-transmitting area and the opaque area of ​​the encoding disk. Figure 2 The dotted line in the middle is not blocked by the vector sensor. When the light passes through the encoder disk and is detected by the photodetector (or photoelectric trigger), an electrical pulse signal in the form of formula (4) can be generated.

[0036] The second vector sensor is placed in the same direction to ensure that the magnetic field modulation signal output by the second vector sensor is also consistent with the reference signal. The high level of the same phase, for easy understanding, can be Figure 2 The x-axis in the diagram is replaced by the z-axis. The y-axis of the plane where the second non-magnetic turntable is located is parallel to the y-axis of the plane where the first non-magnetic turntable is located.

[0037] The lock-in amplifier receives the reference signal from the photodetector 12 , generating a signal with the same frequency as the reference signal and phase The in-phase signal and orthogonal signals : (5); (6); The lock-in amplifier converts the output signal of the first vector sensor into Demodulate with the in-phase signal and the orthogonal signal respectively to obtain the in-phase component and orthogonal components , and then filter out the high-frequency components through a low-pass filter, retain the DC component, and obtain the estimated value of the magnetic field component and : (7); (8); in, and Corresponding to the background magnetic field and Quantity; Indicates low-pass filtering.

[0038] The output signal of the second vector sensor is also extracted through a similar demodulation process to obtain Components, that is, the three-dimensional magnetic field components are finally obtained.

[0039] As an optional embodiment, when the first vector sensor 2 outputs the first magnetic field modulation signal to the analysis module 14 in a wired communication manner, the measurement device further includes a first conductive slip ring 16, a first cable, and a second cable; the first conductive slip ring 16 is arranged in a manner surrounding 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 end 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; and the other end of the second cable is connected to the first signal input end of the analysis module 14, see Figure 3 .

[0040] When the second vector sensor 8 outputs the second magnetic field modulation signal to the analysis module 14 in a wired communication manner, 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 to surround 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 end 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; and the other end of the fourth cable is connected to the second signal input end of the analysis module 14.

[0041] When calibrating or measuring the near-zero magnetic environment in a magnetic shielding device, place the non-magnetic turntable and non-magnetic gear in the magnetic shielding device, pass the non-magnetic support rod and the frame (part) through the through hole of the shielding device, and place the first conductive slip ring and drive motor outside the shielding device. Figure 3 .

[0042] As an optional embodiment, when the first vector sensor 2 outputs the first magnetic field modulation signal to the analysis module 14 in a wired communication manner, 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 to surround 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 end 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; and the other end of the sixth cable is connected to the output end of the power supply 19.

[0043] When the second vector sensor 8 outputs the second magnetic field modulation signal to the analysis module 14 in a wired communication manner, 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 to surround 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 end 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; and the other end of the eighth cable is connected to the output end of the power supply 19.

[0044] 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 may be fixed by being connected to the frame.

[0045] In this embodiment, the non-magnetic turntable is connected to the driving motor via a non-magnetic support rod. The non-magnetic turntable is used to fix the vector sensor and rotate it to achieve modulation of the background magnetic field.

[0046] 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. The power supply line and signal line are connected through a conductive slip ring to avoid the problem of cable entanglement during rotation.

[0047] The non-magnetic support rod and gear are integrally milled and machined. During assembly, the shoulder is inserted through the bearing into the frame and secured with a non-magnetic nut. Through the meshing of two co-modulus gears, the first support rod seamlessly transmits torque when rotating, driving the second support rod to rotate synchronously and at a constant speed.

[0048] When the non-magnetic turntable rotates, the background magnetic field in the magnetic shielding device is modulated in the vector sensor's output signal. The synchronously rotating encoder disk causes the photodetector to generate an electrical pulse reference signal (electrical pulse signal) that is phase-correlated with the modulated signal. This pulse signal is fed into a lock-in amplifier, which serves as a reference for the demodulated signal phase. Demodulation and filtering of the output signal reveal the magnetic field component of the background magnetic field in the magnetic shielding device, located in the plane of the turntable.

[0049] As an optional embodiment, when the first vector sensor 2 outputs the first magnetic field modulation signal to the analysis module 14 in a wireless communication manner, 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.

[0050] Among them, the first conversion circuit 21 and the first non-magnetic antenna 22 are arranged on the disk surface of the first non-magnetic turntable 3; the signal input end of the first conversion circuit 21 is connected to the signal output end of the first vector sensor 2; the signal output end 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.

[0051] 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 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 Figure 4 .

[0052] As an optional embodiment, when the second vector sensor 8 outputs the second magnetic field modulation signal to the analysis module 14 in a wireless communication manner, 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.

[0053] Among them, the third conversion circuit 25 and the third non-magnetic antenna 26 are arranged on the disk surface of the second non-magnetic turntable 9; the signal input end of the third conversion circuit 25 is connected to the signal output end of the second vector sensor 8; the signal output end 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.

[0054] The signal output end of the fourth conversion circuit 27 is connected to the fourth signal input end of the analysis module 14; the signal input end 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 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.

[0055] Herein, 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.

[0056] 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.

[0057] As an optional embodiment, when the first vector sensor 2 outputs the first magnetic field modulation signal to the analysis module 14 via wireless communication, the measuring device also includes a first battery assembly 29; the first battery assembly 29 is arranged on the disk surface of the first non-magnetic turntable 3; the power output end of the first battery assembly 29 is connected to the power supply end of the first vector sensor 2.

[0058] As an optional embodiment, when the second vector sensor 8 outputs a second magnetic field modulation signal to the analysis module 14 via wireless communication, the measuring device also includes a second battery assembly 30; the second battery assembly 30 is arranged on the disk surface of the second non-magnetic turntable 9; the power output end of the second battery assembly 30 is connected to the power supply end of the second vector sensor 8.

[0059] like Figure 4As shown, wireless communication replaces the use of conductive slip rings to route power and signal lines. A non-magnetic turntable is secured to a vector sensor, sensor power supply (i.e., the first or second battery assembly), conversion circuit, and non-magnetic antenna. The vector sensor's output signal is converted to an RF signal by the conversion circuit and then transmitted by the non-magnetic antenna. This signal is received by a non-magnetic antenna (the second or fourth non-magnetic antenna) secured to a through-hole in the shielding device and then transmitted to the conversion circuit outside the shielding device. The conversion circuit converts the RF signal into a digital signal that is then transmitted to a lock-in amplifier. Demodulation and filtering of the digital signal yields the magnetic field component of the background magnetic field within the magnetic shielding device, as reflected on the turntable plane. The second or fourth non-magnetic antenna can also be secured to the frame and positioned externally to the magnetic shielding device, such as below.

[0060] Figure 1 、 Figure 3 and Figure 4 In the figure, the cables are represented by dashed lines.

[0061] Example 2 Based on the same inventive concept, embodiments of the present application also provide a method for measuring extremely weak magnetic field signals using the aforementioned extremely weak magnetic field signal measuring device. The solution to the problem provided by this method is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more of the following embodiments of the method for measuring extremely weak magnetic field signals can be found in the above-described limitations on the extremely weak magnetic field signal measuring device, and will not be further elaborated here.

[0062] In an exemplary embodiment, Figure 5 As shown, a method for measuring an extremely weak magnetic field signal is provided, comprising: Step 101: Place the magnetic field sensing mechanism in the extremely weak magnetic field signal measuring device in 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 11, drive motor 13, and analysis module 14 in the extremely weak magnetic field signal measuring device are located outside the magnetic shielding device 1.

[0063] Step 102: Start the device for measuring the extremely weak magnetic field signal to measure and obtain the three-dimensional magnetic field components in the space to be measured.

[0064] The functions of some components involved in this article are further explained below.

[0065] 1) Magnetic shielding device: Provides a near-zero magnetic environment, shielding against magnetic interference from the external environment, ensuring that only the extremely weak internal magnetic field signal is detected during measurement. Typically made of highly permeable materials such as nickel-iron alloy or superconducting materials, it effectively shields against external magnetic fields.

[0066] 2) Non-magnetic support rods: These connect the non-magnetic turntable to the drive motor, supporting the entire rotation system and ensuring structural stability and non-magnetic properties. They are made of non-magnetic materials such as titanium alloy, stainless steel, or plastic to avoid interference with the magnetic field.

[0067] 3) Drive motor: Provides power to rotate the non-magnetic turntable and non-magnetic gears. The drive motor must have precise speed control capabilities to ensure a constant rotation speed of the turntable. Speed ​​stability directly affects the frequency and accuracy of the modulation signal.

[0068] 4) Non-magnetic turntable: carries the vector magnetic sensor and modulates the magnetic field through rotation. 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 the rotation process.

[0069] 5) Non-magnetic gears: These drive the synchronous rotation of the secondary support rod (secondary support rod), ensuring the synchronized motion of the two non-magnetic turntables. Made of non-magnetic materials such as titanium alloy or specialty plastics, the gears must be designed to ensure precise meshing and minimize mechanical friction and wear.

[0070] 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 to avoid cable entanglement.

[0071] 7) Non-magnetic Antenna: The vector sensor's output signal is converted into an RF signal by a conversion circuit and transmitted to a non-magnetic antenna fixed to the through-hole of the magnetic shielding device. The RF signal is then converted into a digital signal by a circuit outside the magnetic shielding device and transmitted to the lock-in amplifier. This replaces the structure of conductive slip rings securing the power and signal lines, avoiding the mechanical wear and complex wiring problems caused by wire connections, and improving system flexibility.

[0072] 8) Vector sensor: Detects magnetic field changes within the magnetic shield and outputs an electrical signal related to the magnetic field components. The vector sensor coefficients must be calibrated, and bias errors are removed through modulation and demodulation to determine the magnetic field components of the background magnetic field on the turntable plane.

[0073] 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 non-correlated frequencies, improve the signal-to-noise ratio, and ensure accurate extraction of the magnetic field component.

[0074] In this application, wired or wireless communication can be used to accurately measure the background magnetic field in an extremely weak magnetic environment. A magnetic field vector modulation signal is generated by a non-magnetic turntable rotation vector sensor. The modulation signal is demodulated and filtered by a lock-in amplifier to obtain an unbiased background magnetic field signal.

[0075] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, 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.

[0076] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A device for measuring extremely weak magnetic field signals, characterized in that: include: 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 encoding disk, a drive motor, an analysis module, and a frame; The first vector sensor is arranged at the center of the disk surface of the first non-magnetic turntable; the center of the bottom surface of the first non-magnetic turntable is connected to one end of the first support rod in a vertical manner; the other end of the first support rod passes through the center of the encoder disk in a vertical manner and is connected to the rotating shaft of the drive motor; the second vector sensor is arranged at the center of the disk surface of the second non-magnetic turntable; the center of the bottom surface of the second non-magnetic turntable is connected to one end of the second support rod in a vertical manner; the other end of the second support rod is connected to the frame via a bearing; the drive motor is arranged at the bottom of the frame; the bearing is arranged at the top of the frame with its axis perpendicular to the axis of the drive motor; a first gear is arranged on the first support rod; a second gear is arranged on the second support rod; the first gear and the second gear have the same number of teeth; the first support rod and the second support rod are linked by the first gear and the second gear; half of the encoder disk is a light-transmitting area, and the other half is a light-opaque area; the light source and the photodetector are arranged on both sides of the encoder disk and do not rotate with the encoder disk; the light beam emitted by the light source can only pass through the light-transmitting area of ​​the encoder disk to illuminate the photosensitive surface of the photodetector; the light source, the photodetector and the analysis module are arranged at the bottom of the frame; When the driving motor drives the first support rod to rotate, the encoding disk and the second support rod rotate synchronously with the first support rod respectively, the first non-magnetic turntable and the second non-magnetic turntable rotate synchronously with the first support rod and the second support rod respectively, 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; 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 while rotating; The photoelectric detector is used to output an electric pulse reference signal to the analysis module while the encoding disk rotates; The analysis module is used to analyze and process the received first magnetic field modulation signal, the second magnetic field modulation signal and the electric pulse reference signal to determine the three-dimensional magnetic field components in space.

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

3. The device for measuring extremely weak magnetic field signals according to claim 1, characterized in that: When the first vector sensor outputs the first magnetic field modulation signal to the analysis module in a wired communication manner, the measurement device further includes a first conductive slip ring, a first cable, and a second cable; the first conductive slip ring is arranged in a manner of surrounding the 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 end 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; and the other end of the second cable is connected to the first signal input end of the analysis module; When the second vector sensor outputs the second magnetic field modulation signal to the analysis module in a wired communication manner, the measuring device further includes a second conductive slip ring, a third cable, and a fourth cable; the second conductive slip ring is arranged to surround 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 end 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; and the other end of the fourth cable is connected to the second signal input end of the analysis module.

4. The device for measuring extremely weak magnetic field signals according to claim 3, characterized in that: When the first vector sensor outputs the first magnetic field modulation signal to the analysis module in a wired communication manner, 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 in a manner surrounding 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; and the other end of the sixth cable is connected to the output terminal of the power supply; When the second vector sensor outputs the second magnetic field modulation signal to the analysis module in a wired communication manner, 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 to surround 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; and the other end of the eighth cable is connected to the output terminal of the power supply.

5. The device for measuring extremely weak magnetic field signals according to claim 1, characterized in that: When the first vector sensor outputs the first magnetic field modulation signal to the analysis module in a wireless communication manner, 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 arranged on the disk surface of the first non-magnetic turntable; the signal input end of the first conversion circuit is connected to the signal output end of the first vector sensor; the signal output end 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 end of the second conversion circuit is connected to the third signal input end of the analysis module; the signal input end 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 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 device for measuring extremely weak magnetic field signals according to claim 1, characterized in that: When the second vector sensor outputs the second magnetic field modulation signal to the analysis module in a wireless communication manner, 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 arranged on the disk surface of the second non-magnetic turntable; the signal input end of the third conversion circuit is connected to the signal output end of the second vector sensor; the signal output end 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 end of the fourth conversion circuit is connected to the fourth signal input end of the analysis module; the signal input end 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 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 device for measuring 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 comprises a first battery assembly; the first battery assembly is disposed on the disk surface of the first non-magnetic turntable; and the power output end of the first battery assembly is connected to the power supply end of the first vector sensor.

8. The device for measuring 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 arranged on the disk surface of the second non-magnetic turntable; the power output end of the second battery assembly is connected to the power supply end of the second vector sensor.

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

10. A method for measuring an extremely weak magnetic field signal using the extremely weak magnetic field signal measuring device according to any one of claims 1 to 9, characterized in that: include: Placing the magnetic field sensing mechanism in the extremely weak magnetic field signal measuring device 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, drive motor, and analysis module of the extremely weak magnetic field signal measuring device are located outside the magnetic shielding device; The device for measuring the extremely weak magnetic field signal is started to measure and obtain the three-dimensional magnetic field components in the space to be measured.

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