Weak magnetic signal detection system and detection method thereof

Abstract

The present application relates to the technical field of extremely weak magnetic detection, and provides an extremely weak magnetic signal detection system and a detection method thereof, the system comprising a magnetic shielding component, a transmission component and a detection component, the magnetic shielding component being internally structured with a shielding cavity, a support frame in the transmission component being located outside the magnetic shielding component; a driving assembly being arranged on the support frame; a transmission assembly being arranged on the support frame, one end of the transmission assembly being in transmission cooperation with the driving assembly, the other end of the transmission assembly being arranged through the magnetic shielding component and extending into the shielding cavity; a magnetometer in the detection component being fixedly arranged on the transmission assembly, a detection site of the magnetometer being located in a uniform area of a magnetic field in the shielding cavity, the magnetometer being used for detecting residual magnetism and magnetic noise of a material to be measured; a control system being located outside the magnetic shielding component, the control system being connected with the magnetometer and the driving assembly respectively, the control system being used for collecting and processing detection signals of the magnetometer and being used for controlling the driving assembly to work, the present application can detect residual magnetism and magnetic noise of components working in an extremely weak magnetic environment, and can ensure product quality.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of extremely weak magnetic detection, and particularly relates to an extremely weak magnetic signal detection system and a detection method thereof. BACKGROUND

[0002] The extremely weak magnetic signal includes residual magnetism and magnetic noise. The residual magnetism refers to the magnetism retained by a material after an external magnetic field is removed, and the magnetic noise refers to random magnetic field fluctuations in a material or environment. The residual magnetism (such as an nT-level static magnetic field) and the magnetic noise (such as an fT level dynamic magnetic field fluctuation) are far lower in intensity than the daily environmental magnetic field, but can still produce non-negligible interference on components working in an extremely weak magnetic environment.

[0003] Therefore, the residual magnetism and the magnetic noise are one of important indicators of the components working in an extremely weak magnetic environment. In the related art, the components working in an extremely weak magnetic environment often discover the influence on product performance after the product is formed. In a product with high production cost, once a substandard product appears, it will cause serious economic losses. Therefore, the present application provides an extremely weak magnetic signal detection system. SUMMARY

[0004] The present application provides an extremely weak magnetic signal detection system and a detection method thereof, which can solve the above technical defects in the prior art, can batch detect residual magnetism and magnetic noise of components working in an extremely weak magnetic environment, realize product sorting, ensure product quality, and further improve production efficiency.

[0005] A first aspect of the present application provides an extremely weak magnetic signal detection system, comprising:

[0006] A magnetic shielding component, which is internally structured with a shielding cavity;

[0007] A conveying component, comprising:

[0008] A support frame body, which is located on one side of the magnetic shielding component and is arranged away from the shielding cavity;

[0009] A driving assembly, which is arranged in the support frame body;

[0010] A conveying assembly, which is arranged in the support frame body, one end of the conveying assembly is in transmission cooperation with the driving assembly, and the other end is arranged through the magnetic shielding component and extends into the shielding cavity;

[0011] A detection component, comprising:

[0012] A magnetometer, which is fixedly arranged on the conveying assembly extending into the shielding cavity, and a detection site of the magnetometer is located in a uniform region of a magnetic field in the shielding cavity, and is used for residual magnetism and magnetic noise detection on a material to be measured;

[0013] The control system is located on one side of the magnetic shielding component and is disposed away from the shielding cavity. The control system is electrically connected to the magnetometer and the drive assembly respectively, and is used to collect and process the detection signal of the magnetometer and to control the operation of the drive assembly.

[0014] According to the extremely weak magnetic signal detection system provided by the present invention, the transmission component includes:

[0015] A support unit is provided on the support frame, the support unit is provided with a rotatable transmission shaft, and the support unit is provided with a mounting bracket at a position away from the drive component;

[0016] A conveying unit is arranged around the drive shaft, and a loading fixture is provided on the conveying unit;

[0017] The magnetometer is mounted on the mounting bracket, and the material to be measured is placed on the loading fixture.

[0018] The extremely weak magnetic signal detection system provided by the present invention further includes a first position detection element and a second position detection element, both of which are electrically connected to the control system.

[0019] The first position detection element is located near the support frame of the conveying assembly and is used to detect the starting position of the material to be tested;

[0020] The second position detection element is located on the magnetic shielding component and is used to detect the preset trigger position of the material to be tested within the shielding cavity.

[0021] The extremely weak magnetic signal detection system provided by the present invention includes a control system comprising:

[0022] A data acquisition component, electrically connected to the magnetometer, is used to acquire the detection signal of the magnetometer;

[0023] The industrial control computer is equipped with a control module and a signal processing and analysis module. The control module is electrically connected to the drive component and is used to control the operation of the drive component. The signal processing and analysis module is electrically connected to the data acquisition component and is used to analyze the acquired detection signals and output the detection results.

[0024] The extremely weak magnetic signal detection system provided by the present invention includes, in which the magnetic shielding component comprises:

[0025] Vibration isolation platform;

[0026] A magnetic shielding barrel is disposed on the vibration isolation platform, and the magnetic shielding barrel forms the shielding cavity, wherein the residual magnetism in the shielding cavity is less than 1nT;

[0027] The magnetic shielding barrel has at least one opening, and a shielding cover is provided at the position of at least one of the openings. The conveying component passes through the opening.

[0028] A second aspect of the present invention provides a detection method based on the extremely weak magnetic signal detection system described in any one of the preceding claims, comprising the following steps:

[0029] The material to be tested is fixed on the loading fixture of the conveying assembly;

[0030] The conveying assembly is driven to operate, allowing the material to be tested to enter the shielding cavity of the magnetic shielding component;

[0031] When the material to be tested is located in the detection area of ​​the magnetometer, the residual magnetism and magnetic noise of the material to be tested are collected and processed.

[0032] Determine that the material to be tested has moved to a preset trigger position, record the trigger time corresponding to the preset trigger position, and record the running time of the material to be tested after it starts from the preset trigger position in real time;

[0033] When it is determined that the current position of the material to be tested is within the detection area of ​​the magnetometer at the current operating time, the material to be tested is controlled to perform reciprocating motion on the conveying component, and the magnetic induction intensity of the magnetometer is collected in real time during the reciprocating motion of the material to be tested, and a curve of the magnetic induction intensity changing periodically with the sampling point is generated.

[0034] The remanence of the material to be tested is determined by the curve showing the periodic change of magnetic induction intensity with the sampling point.

[0035] According to the detection method of the extremely weak magnetic signal detection system provided by the present invention, when determining that the current position of the material to be tested is located in the detection area of ​​the magnetometer at the current operating time, controlling the material to be tested to perform reciprocating motion on the conveying assembly includes:

[0036] The current position of the material to be tested at the current operating time is determined to be directly below the magnetometer, and the material to be tested is controlled to run on the conveying component for a first preset time period.

[0037] When the material to be tested is determined to run on the conveying component for a first preset time period, the material to be tested is controlled to run in reverse on the conveying component for a second preset time period, wherein the second preset time period is equal to twice the first preset time period.

[0038] According to the detection method of the extremely weak magnetic signal detection system provided by the present invention, the step of determining the remanence of the material to be tested based on the curve of periodic change of magnetic induction intensity with sampling points includes:

[0039] Select any complete period from the curve of the periodic change of magnetic induction intensity with the sampling point as the target period;

[0040] The difference between the maximum and minimum values ​​of magnetic induction intensity within the target period is determined, and the difference is the remanence of the material to be tested.

[0041] According to the detection method of the extremely weak magnetic signal detection system provided by the present invention, when determining that the material to be tested is located in the detection area of ​​the magnetometer, the magnetic noise of the material to be tested is collected and processed, including:

[0042] The first average sensitivity value of the magnetometer under no-load conditions is obtained, wherein the no-load conditions refer to the background sensitivity data collected by the magnetometer in the frequency range of 2-30Hz when the loading fixture is not carrying the material to be measured.

[0043] Determine that the material to be tested has moved to a preset trigger position, record the trigger time corresponding to the preset trigger position, and record the running time of the material to be tested after it starts from the preset trigger position in real time;

[0044] When it is determined that the current position of the material to be tested is directly below the magnetometer at the current operating time, the material to be tested is controlled to stop moving, and the updated sensitivity data of the magnetometer is recorded.

[0045] The magnetic noise of the material to be tested is determined by the difference between the second average sensitivity value in the 2-30Hz frequency range of the non-first updated sensitivity data and the first average sensitivity value of the magnetometer under no-load conditions.

[0046] The extremely weak magnetic signal detection system provided by this invention, through modular design of magnetic shielding components, transmission components, and detection components, can perform batch detection of residual magnetism and magnetic noise on materials under test (components that rely on extremely weak magnetic environments), enabling product sorting, ensuring product quality, and thus improving production efficiency. Furthermore, the extremely weak magnetic signal detection system adopts a quick-assembly design, making it easy to adapt to different application scenarios.

[0047] Compared to traditional extremely weak magnetic field detection systems, the multi-layered composite magnetic shielding components suppress the background magnetic field to the nT level, combined with the high sensitivity (fT) of the SERF atomic magnetometer. This system can detect residual magnetism (such as weak magnetic signals in biological samples) or magnetic noise (such as magnetic anisotropic noise in nanomaterials) that traditional systems cannot distinguish. The transfer component supports continuous testing of multiple samples and enables automatic entry and exit of the test material from the shielded cavity, avoiding mechanical disturbances introduced by manual operation. This not only ensures measurement accuracy but also improves testing efficiency.

[0048] The detection method of the extremely weak magnetic signal detection system provided by this invention can support continuous detection of multiple samples, which can not only ensure measurement accuracy, but also improve detection efficiency. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0050] Figure 1 This is a schematic diagram of the structure of the extremely weak magnetic signal detection system provided in an embodiment of the present invention.

[0051] Figure 2 This is a schematic diagram of the positional relationship of the extremely weak magnetic signal detection system provided in an embodiment of the present invention.

[0052] Figure 3 This is a schematic diagram of the transmission component in the extremely weak magnetic signal detection system provided in an embodiment of the present invention.

[0053] Figure 4 This is a system block diagram of the control system in the extremely weak magnetic signal detection system provided in the embodiments of the present invention.

[0054] Figure 5 This is a partial top view of the extremely weak magnetic signal detection system provided in an embodiment of the present invention.

[0055] Figure 6 This is a periodic change diagram of the detection process of the extremely weak magnetic signal detection system provided in this embodiment of the invention.

[0056] Figure 7 This is a flowchart of the detection method of the extremely weak magnetic signal detection system provided in the embodiments of the present invention.

[0057] Figure 8 This is a detailed flowchart of the detection method of the extremely weak magnetic signal detection system provided in the embodiments of the present invention.

[0058] Figure label:

[0059] 10. Magnetic shielding components; 11. Vibration isolation platform; 12. Magnetic shielding barrel;

[0060] 20. Conveying component; 21. Support frame; 22. Drive assembly; 23. Conveying assembly; 231. Support unit; 232. Conveying unit; 233. Mounting bracket;

[0061] 30. Detection components; 31. Magnetometer; 32. Data acquisition components; 33. Industrial control computer;

[0062] 40. Loading fixtures. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0064] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0065] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0067] Figure 1 This is a schematic diagram of the structure of the extremely weak magnetic signal detection system provided in an embodiment of the present invention. Figure 2This is a schematic diagram of the positional relationship of the extremely weak magnetic signal detection system provided in an embodiment of the present invention.

[0068] See Figure 1 and Figure 2 This invention provides an extremely weak magnetic signal detection system, which adopts a modular design. The components work together to detect residual magnetism (e.g., nT level) and magnetic noise (e.g., fT level) in components that rely on extremely weak magnetic environments. High-precision detection (level 1). This extremely weak magnetic signal detection system includes a magnetic shielding component 10, a transmission component 20, and a detection component 30.

[0069] The magnetic shielding component 10 is a multi-layer composite shielding cavity. The core layer consists of four layers of permalloy (thickness 0.1-0.3mm) and one layer of aluminum (thickness 1-2mm) stacked alternately along the magnetic field direction (axial direction). The low coercivity and high magnetic permeability of the permalloy are used to shunt and shield the static magnetic field, and the aluminum layer is used to suppress eddy current interference.

[0070] The internal structure of the magnetic shielding component 10 includes a shielding cavity. The size of the shielding cavity is customized according to the size of the material to be tested. The openings (such as the inlet and outlet) of the shielding cavity are equipped with openable magnetic doors (such as spliced ​​silicon steel sheets). When closed, they are tightened with bolts to ensure the continuity of the magnetic circuit.

[0071] The residual magnetism within the shielding cavity can be calibrated using a nuclear magnetic resonance (NMR) probe or a high-precision magnetometer to ensure that the background magnetic field within the shielding cavity is <0.1 nT (static) or <1 pT / (Dynamic) to meet the requirements of extremely weak magnetic field detection.

[0072] This invention utilizes the magnetic shunting effect of multilayer permalloy on static magnetic fields (the external magnetic field is shunted through the high-permeability material, reducing the magnetic flux entering the shielding cavity), combined with the suppression of high-frequency eddy currents by the aluminum layer, to reduce the background magnetic field in the shielding cavity to an extremely weak level, providing a zero-magnetic environment for the detection of extremely weak magnetic signals.

[0073] The conveying component 20 includes a support frame 21, a drive assembly 22, and a conveying assembly 23.

[0074] The support frame 21 is located on one side of the magnetic shielding component 10 and is positioned away from the shielding cavity. This means that the support frame 21 is located outside the magnetic shielding component 10 of the shielding cavity. The support frame 21 can be made of an aluminum alloy frame, which has high rigidity and low magnetic susceptibility, thus avoiding the introduction of additional magnetic fields through its own magnetization. Adjustable feet can be installed at the bottom of the support frame 21 to ensure that the support frame 21 is level.

[0075] The drive assembly 22 is located on the support frame 21. The drive assembly 22 can use a stepper motor and a planetary reducer to achieve power output, and is connected to the transmission assembly 23 through a synchronous belt. The drive speed is adjustable and supports precise start and stop control. Alternatively, the drive assembly 22 can use a stepper motor and a planetary reducer to achieve power output, and be connected to the transmission assembly 23 through gears.

[0076] The conveying component 23 is used to convey the material to be tested from the outside of the magnetic shielding component 10 to the shielding cavity. One end of the conveying component 23 is fixed to the output shaft of the drive component 22, and the other end of the conveying component 23 extends into the shielding cavity through the magnetic sealing port at the entrance of the shielding cavity of the magnetic shielding component 10, ensuring that the sample is not subject to additional vibration or magnetic field disturbance during the conveying process.

[0077] The detection component 30 includes a magnetometer 31 and a control system. The magnetometer 31 is fixedly mounted on the transmission assembly 23 located inside the shielded cavity. The detection point of the magnetometer 31 is located in the uniform region of the magnetic field inside the shielded cavity. The magnetometer 31 is used to detect the residual magnetism and magnetic noise of the material to be tested.

[0078] Among them, the magnetometer 31 can be a SERF atomic magnetometer (sensitivity up to fT). The magnetometer 31 is fixed on the conveying assembly 23. The detection point of the magnetometer 31 is located in the most uniform magnetic field area inside the shielded cavity (that is, the center of the shielded cavity). When the material to be tested moves to the detection point, the magnetometer 31 is facing the upper bottom surface of the material to be tested (5-10mm away).

[0079] Among them, the SERF atomic magnetometer, due to its ultra-high sensitivity, can measure the remanence and magnetic noise of materials with an accuracy of up to tens of fT. It can detect remanence and magnetic noise. Therefore, this embodiment of the invention uses a SERF atomic magnetometer as an example for illustration.

[0080] The control system is located on one side of the magnetic shielding component 10 and away from the shielding cavity, that is, on the outside of the magnetic shielding component 10. The control system is connected to the magnetometer 31 and the drive assembly 22, respectively, and is used to collect and process the detection signal of the magnetometer 31 and control the operation of the drive assembly 22. The control system is based on an industrial computer 33 and integrates a data acquisition module (sampling rate 10kHz), a signal processing and analysis module, and a control module.

[0081] It is understood that the extremely weak magnetic signal detection system provided in this embodiment of the invention, through modular arrangement of the magnetic shielding component 10, the conveying component 20, and the detection component 30, can perform residual magnetism and magnetic noise detection on batches of materials to be tested (components that rely on extremely weak magnetic environments), thereby achieving product sorting, ensuring product quality, and improving production efficiency. At the same time, the extremely weak magnetic signal detection system adopts a quick assembly design, which facilitates adaptation to different application scenarios.

[0082] Compared to traditional extremely weak magnetic field detection systems, the multi-layered composite magnetic shielding barrel 12 suppresses the background magnetic field to the nT level, combined with the high sensitivity (fT) of the SERF atomic magnetometer 31. This system can detect residual magnetism (such as weak magnetic signals in biological samples) or magnetic noise (such as magnetic anisotropic noise in nanomaterials) that traditional systems cannot distinguish. The conveying component 20 supports continuous multi-sample testing and enables automatic entry and exit of the analyte into the shielded cavity, avoiding mechanical disturbances introduced by manual operation. This not only ensures measurement accuracy but also improves testing efficiency. The conveying component 20 enables automatic entry and exit of the analyte into the shielded cavity, avoiding mechanical disturbances introduced by manual operation; simultaneously, the conveying component 20 supports continuous multi-sample testing, ensuring measurement accuracy and improving testing efficiency.

[0083] Figure 3 This is a schematic diagram of the structure of the transmission component 20 in the extremely weak magnetic signal detection system provided in this embodiment of the invention.

[0084] See Figure 3 In some embodiments of the present invention, the transmission component 23 is the core execution module of the extremely weak magnetic signal detection system, used to stably and accurately transport the material to be tested to the detection area of ​​the magnetometer 31, while ensuring the consistency of the sample position during the detection process.

[0085] The conveying assembly 23 includes a support unit 231 and a conveying unit 232. The support unit 231 can be configured as a frame structure, made of polyetheretherketone or polyoxymethylene, and the support unit 231 is fixed to the support frame 21. The support unit 231 integrates at least two sets of parallel drive shafts, which are rotatably mounted at both ends of the support unit 231 via bearings.

[0086] A mounting bracket 233 is fixed to the top or side of the support unit 231 by non-magnetic PEEK bolts. The mounting bracket 233 can be gantry-shaped or "L"-shaped. A waist-shaped hole can be opened on the mounting bracket 233 (for adjusting the height and horizontal position of the magnetometer 31). The magnetometer 31 is fixed to the mounting bracket 233 by non-magnetic PEEK bolts, ensuring that its detection window is directly facing the movement path of the loading fixture 40 of the conveying unit 232 and 5-10mm away from the material to be measured to avoid mechanical interference.

[0087] The conveying unit 232 has a closed ring structure and can be a conveyor belt (such as a PTFE-coated canvas belt), a lightweight chain, or a synchronous belt wound between two drive shafts. The conveying unit 232 is equipped with a loading fixture 40, and the width of the conveying unit 232 is customized according to the size of the loading fixture 40 to ensure that the loading fixture 40 fits stably.

[0088] The loading fixture 40 can be modularly designed and made of non-magnetic materials (such as polyetheretherketone or polyoxymethylene). Its bottom has a slot (such as a T-slot or dovetail slot) that matches the conveying unit 232, ensuring that the loading fixture 40 moves synchronously with the conveying unit 232 without deviation. The top of the loading fixture 40 has a sample positioning groove, the size of which is adapted to the material to be tested. A silicone pad can be attached to the inside of the sample positioning groove to increase friction and prevent slippage of the material during transport.

[0089] In operation, the extremely weak magnetic signal detection system provided in this embodiment of the invention places the material to be tested in the positioning slot of the loading fixture 40. The loading fixture 40 is moved to the starting point of the conveying path (i.e., the outside of the shielding cavity) by the conveying unit 232. The driving component 22 drives one of the transmission shafts to rotate, and the conveying unit 232 drives the loading fixture 40 to move at a constant speed toward the magnetic shielding cavity due to friction.

[0090] When the loading fixture 40 reaches the detection area of ​​the magnetometer 31, the position detection unit (such as a photoelectric sensor) is triggered, and the motor in the drive assembly 22 operates in the corresponding mode. The magnetometer 31 begins to detect the residual magnetism or magnetic noise of the material to be tested, and the control system records the data synchronously. After the detection is completed, the motor drives the transmission shaft in reverse, and the conveying unit 232 moves the loading fixture 40 out of the shielded cavity, completing a single conveying operation.

[0091] Specifically, in some embodiments of the present invention, the extremely weak magnetic signal detection system further includes a first position detection element and a second position detection element, both of which are electrically connected to the control module; the first position detection element is located on the conveying assembly 23 near the support frame 21 and is used to detect the starting position of the material to be tested; the second position detection element is located on the magnetic shielding component 10 and is used to detect the preset trigger position of the material to be tested in the shielding cavity, which can be understood as a specific position on the conveying assembly 23.

[0092] Since remanence is essentially the weak magnetic field remaining after a material is magnetized, the magnetometer 31 can indirectly infer the remanence characteristics of the material through an inversion algorithm of the spatial distribution of the magnetic field, combined with its own high-resolution magnetic field gradient detection capability. However, the second position detection element is susceptible to environmental noise interference and is difficult to stably detect when the electromagnetic environment becomes more complex. Furthermore, the second position detection element (such as a position sensor) can easily affect the detection of the magnetometer 31. Therefore, the second position detection element is located on the magnetically shielded component 10 and at a position far away from the magnetometer 31.

[0093] The embodiments of the present invention can realize the full-process automation of material conveying, positioning and detection by the linkage control of the drive component 22 and the magnetometer 31. Compared with traditional manual operation detection, it can shorten the single detection time and improve detection efficiency.

[0094] This setup, by monitoring the position of the material to be tested on the conveying component 23 in real time, provides dynamic position feedback to the control module, ensuring that the sample accurately reaches the detection area of ​​the magnetometer 31. No manual intervention is required to adjust the position of the material to be tested, shortening the single detection time and improving detection efficiency.

[0095] The first position detection element can be a contact position sensor or a proximity position sensor, such as a limit switch or a photoelectric sensor. The first position detection element is used to detect the starting position of the loading fixture 40 or the material to be measured.

[0096] The second position detection element can employ a single sensor or a multi-sensor fusion scheme, and can be used for triggered position detection and continuous position tracking. Triggered position detection can use contact or proximity position sensors, such as photoelectric sensors. Continuous position tracking can use an encoder.

[0097] The photoelectric sensor can be a through-beam photoelectric sensor, with the transmitter and receiver respectively mounted at the mounting holes on the magnetic shielding component 10. The transmitter emits an infrared beam, and the receiver receives the beam and outputs a switching signal (TTL high / low level). When the material to be measured or the mounting fixture 40 blocks the beam, the receiver outputs a low-level signal, sending the detection signal at the preset trigger position to the control system.

[0098] An incremental rotary encoder can be selected and installed at the end of the drive shaft of the drive assembly 22, rotating synchronously with the drive shaft via a coupling. The encoder outputs two-phase A / B sine wave signals, and the pulse count is collected in real time by the counter module of the industrial control computer 33 and converted into the displacement of the transmission assembly 23.

[0099] When the extremely weak magnetic signal detection system provided in this embodiment of the invention is working, the material to be tested is placed in the positioning slot of the loading fixture 40. After the first position detection element detects that the loading fixture 40 is ready, it drives the loading fixture 40 to move through the conveying unit 232.

[0100] In this system, the drive assembly 22 drives one of the transmission shafts to rotate, and the conveying unit 232, due to friction, moves the workpiece 40 at a constant speed toward the magnetic shielding cavity. When the workpiece 40 triggers the second position detection element (such as a photoelectric sensor), the trigger time corresponding to the preset trigger position is recorded. The conveying unit 232 continues to drive the workpiece 40 and records the movement time of the workpiece 40 from the preset trigger position in real time. When the workpiece 40 reaches the detection area of ​​the magnetometer 31 at the current position corresponding to the current running time, the motor in the drive assembly 22 operates in the corresponding mode, and the magnetometer 31 begins to detect the residual magnetism or magnetic noise of the material to be tested. The control system records the data synchronously. After the detection is completed, the motor drives the transmission shaft in reverse, and the conveying unit 232 moves the workpiece 40 out of the shielding cavity, completing a single conveying operation.

[0101] The embodiments of the present invention can realize the full-process automation of material conveying, positioning and detection by the linkage control of the drive component 22 and the magnetometer 31. Compared with traditional manual operation detection, it can shorten the single detection time and improve detection efficiency.

[0102] Figure 4 This is a system block diagram of the control system in the extremely weak magnetic signal detection system provided in the embodiments of the present invention.

[0103] See Figure 4 In some embodiments of the present invention, the control system is used to coordinate the operation of the drive component 22 (such as a motor) and the magnetometer 31, and to complete the entire process of signal processing from acquisition to analysis.

[0104] The control system includes a data acquisition component 32 and an industrial computer 33. The data acquisition component 32 is fixed to the expansion slot of the motherboard of the industrial computer 33 or an independent chassis, and is electrically connected to the magnetometer 31 through a shielded cable (such as a twisted pair shielded cable) to acquire the detection signal of the magnetometer 31.

[0105] The data acquisition component 32 includes an analog signal conditioning module, a high-speed analog-to-digital converter, a digital isolator, and an interface module. The weak electrical signal (such as nV-level voltage or pA-level current) output by the magnetometer 31 is amplified and conditioned by a low-pass filter in the analog signal conditioning module to improve the signal-to-noise ratio. The high-speed analog-to-digital converter can use a 24-bit resolution, 10kHz sampling rate Δ-Σ type ADC to ensure accurate sampling of low-frequency signals in the 2-30Hz range. The digital isolator isolates the magnetometer 31 from the industrial computer 33 via optocouplers or magnetic couplings, blocking electromagnetic interference. The interface module is matched with the magnetometer 31 (such as the RS485 interface of a SERF atomic magnetometer) to achieve stable communication.

[0106] The industrial control computer 33 is an industrial-grade computer, equipped with a control module and a signal processing and analysis module. The control module sends pulse / direction commands (such as the 24V pulse signal of a stepper motor) to the drive component 22 through a motion control card API (such as NI-MDtiDn) to control the start and stop and speed adjustment of the transmission component 23. The signal processing and analysis module is electrically connected to the data acquisition component 32 and is used to analyze the acquired detection signals and output the detection results.

[0107] In some embodiments of the present invention, the magnetic shielding component 10 includes a vibration isolation platform 11 and a magnetic shielding barrel 12. The magnetic shielding barrel 12 is fixedly disposed on the vibration isolation platform 11. The vibration isolation platform 11 is used to isolate external low-frequency vibrations and reduce the vibrations transmitted to the magnetic shielding barrel 12.

[0108] The vibration isolation platform 11 can adopt a composite structure of springs and rubber pads. The bottom edge of the magnetic shielding barrel 12 is designed with three or four non-magnetic stainless steel lugs to connect with the vibration isolation platform 11. Rubber washers are installed between the bolts and the lugs to avoid metal-to-metal contact. This design achieves the dual functions of vibration isolation and magnetic field shielding, providing a stable physical environment for extremely weak magnetic field detection.

[0109] The magnetic shielding barrel 12 can be cylindrical or prismatic in shape. The interior of the magnetic shielding barrel 12 is constructed with a shielding cavity, and the residual magnetism in the shielding cavity is less than 1nT. The vibration isolation platform 11 is located inside the shielding cavity.

[0110] The magnetically shielded container 12 has at least one opening (such as an inlet and an outlet). The width of each opening must be greater than the maximum cross-section of the conveyor assembly 23 (e.g., a conveyor belt width of 100mm and an opening width of 120mm). A 5-10mm gap is reserved in the height direction to be filled with a silicone pad to avoid magnetic field leakage caused by mechanical contact and to ensure that the sample is not subjected to additional vibration or magnetic field disturbance during transport. The opening is sealed with a shielding cover, and the other end of the conveyor assembly 23 passes through the opening and extends into the shielding cavity (e.g., spliced ​​from silicon steel sheets). When closed, it is secured with bolts to ensure the continuity of the magnetic circuit.

[0111] For example, the magnetic shielding barrel 12 is designed with openings on both sides. The material to be tested enters the magnetic shielding barrel 12 through one opening and exits through the other opening, replacing the current design with an opening at one end. However, the advantage of an opening at one end is a better internal magnetic field environment and a higher noise floor for the SERF atomic magnetometer. If openings are made at both ends, the axial dimension of the magnetic shielding barrel 12 could be increased to avoid sacrificing some of the performance of the SERF atomic magnetometer.

[0112] Figure 5 This is a partial top view of the extremely weak magnetic signal detection system provided in an embodiment of the present invention. Figure 6 This is a periodic change diagram of the detection process of the extremely weak magnetic signal detection system provided in this embodiment of the invention.

[0113] Continue reading Figures 1 to 3 And see also Figure 5 and Figure 6 When assembling the extremely weak magnetic signal detection system provided in this embodiment of the invention, the probe of the SERF atomic magnetometer is inserted into the groove of the mounting bracket 233 and inserted to the bottom (there is a limit within the groove). The transmission component 23 is placed inside the magnetic shielding barrel 12, ensuring that the transmission component 23 is horizontal and centered, to avoid interference between the transmission component 23 and the magnetic shielding barrel 12, so as to affect the operation of the transmission component 23.

[0114] When the power is turned on, the green light at the transmitting end of the first position detection element on the transmission component 23 should be constantly lit, and the green light on the power box screen and the power indicator above the screen should also be constantly lit, indicating that the extremely weak magnetic signal detection system is in normal working condition.

[0115] The loading fixture 40 is placed on the outermost side of the conveying assembly 23. The red light on the receiver of the first position detection element on the conveying assembly 23 remains constantly lit, indicating that the first position detection element has sensed the loading fixture 40. The entire extremely weak magnetic signal detection system is now complete. Figure 1 As shown.

[0116] After the extremely weak magnetic signal detection system is assembled, the relevant parameters are modified on the control module of the transmission component 23 to meet the requirements of different working states, as follows:

[0117] To determine the working status, click the switch button between 1 and 2. Mode 1 is the material residual magnetism test mode, and Mode 2 is the material magnetic noise test mode. The core difference between Mode 1 (material residual magnetism test) and Mode 2 (material magnetic noise test) lies in their different test objectives. Therefore, after loading the material, select the appropriate working mode according to the actual needs.

[0118] When Mode 1 is in operation, the "stop time after preset trigger position" is set to control the movement time required for the payload fixture 40 to move from the preset trigger position to the detection area of ​​the SERF atomic magnetometer. This detection area can be defined as... Figure 5 The region extends from point B to point C. Point B is located in front of the SERF atomic magnetometer probe, point A is directly below the SERF atomic magnetometer, and point C is behind the SERF atomic magnetometer. Points C and B are symmetrically distributed with respect to point A, where the SERF atomic magnetometer probe is located.

[0119] For example, the movement time required for the payload fixture 40 to move from the "preset trigger position" (marked by the second position detection element) to point B in front of the probe of the SERF atomic magnetometer can be controlled. By controlling the movement time, the positional accuracy of the payload fixture 40 at point B can be indirectly controlled.

[0120] The "Number of Detections" setting controls the number of times the payload 40 moves back and forth under the probe of the SERF atomic magnetometer. This refers to the number of times the payload 40 moves back and forth under the probe (with point A as the center area). For example, moving from point B to point C and then back to point B constitutes one round trip.

[0121] By collecting residual magnetism within the detection area through multiple round trips and averaging the data, random noise interference can be reduced, improving measurement accuracy. If the material exhibits residual magnetic relaxation (the magnetic field changes slowly over time), multiple round trips can be used to observe whether the signal is stable and to determine the long-term characteristics of the residual magnetism.

[0122] The "Preset Trigger Position Reciprocating Time" is set to control the time for the payload fixture 40 to reciprocate under the probe of the SERF atomic magnetometer in a single reciprocating motion, that is, the time required for the payload fixture 40 to complete one complete reciprocating motion (from point C to point B, and then back to point C).

[0123] Since the distance from point C to the probe center must be symmetrical to the distance from point B to the probe center (i.e., the probe is located at the midpoint between points C and B), and distance = speed × time, if the round-trip time of the loading fixture 40 is fixed (i.e., the total time for a single round trip is fixed), and the detection system defaults to a constant round-trip speed, then the distances from points C and B to the probe must be equal (symmetrical). For example, if the round-trip time is T, the one-way time is T / 2, and the speed v is fixed, then the distance from point C to the probe is v × (T / 2), and the distance from point B to the probe is similar.

[0124] When mode 2 is in operation, the "stop time after preset trigger position" is set, controlling the workpiece 40 to move from the preset trigger position (the calibration position of the second position detection element) to directly below the probe. Figure 5The time required to reach point A as described in the figure. The purpose is to ensure that the mounting fixture 40 accurately reaches point A (the target position for magnetic noise testing) and avoids distortion of noise data due to positional deviation. For example, if the mounting fixture 40 is not aligned with the center of the probe, stray magnetic fields may be collected instead of the noise from the material itself.

[0125] The setting "Time the payload 40 stops below the probe" controls the duration for which the payload 40 remains directly below the probe of the SERF atomic magnetometer. Since magnetic noise typically manifests as random, minute magnetic field fluctuations, continuous data acquisition over a long period is required to statistically analyze its characteristics (such as power spectral density). The note requiring a "dwell time slightly longer than 1 minute" ensures that a sufficient number of noise samples are collected, avoiding insufficient data or random errors due to excessively short time.

[0126] It should be noted that in Mode 2, which is in working condition, there is no need for back-and-forth movement. Therefore, the "back-and-forth time" function has been changed from "controlling time" to "controlling dwell time," simplifying parameter settings. Furthermore, the test objective of Mode 2 (noise monitoring) does not rely on multiple back-and-forth movements; a single long dwell time is sufficient to meet data collection requirements. Therefore, there is no need to set functions such as "number of detections" or "preset trigger position back-and-forth time."

[0127] Understandably, Mode 1 (remanence test) ensures that the fixture 40 moves accurately, stably, and symmetrically in front of the probe by controlling the stop time after the preset trigger position, the number of tests, and the reciprocating time, thereby collecting high-quality remanence data. Mode 2 (magnetic noise test) ensures that the fixture 40 remains stably under the probe for a long time by controlling the stop time and dwell time after the preset trigger position, thereby collecting sufficient noise samples to meet the requirements of magnetic field noise characteristic analysis.

[0128] SERF atomic magnetometer preparation:

[0129] When testing residual magnetism, the material to be tested on the fixture 40 should be approximately 0.5 cm away from the probe of the SERF atomic magnetometer, meaning it needs to be 0.5 cm higher than the highest point of the fixture 40. Figure 1 As shown. Close the shielding cover of the magnetic shielding barrel 12. The shielding cover is sequentially locked into the opening position of the magnetic shielding barrel 12. The shielding cover needs to be placed vertically to avoid affecting the passage of the loading fixture 40 through the shielding cover.

[0130] The SERF atomic magnetometer industrial control computer 33 in the detection system is adjusted to an idle sampling state to ensure that the average sensitivity of the sensor in the 2-30Hz range is less than or equal to 30fT. .

[0131] When performing a residual magnetism test:

[0132] Confirm that the extremely weak magnetic signal detection system is in mode 1. Turn the leftmost button at the start of the conveyor belt to the "automatic" position, and click the green "cycle start" button in the middle. The conveyor belt will then begin to move.

[0133] When the material to be tested moves with the conveyor belt to Figure 5 At point A, the reciprocating motion will begin, and the industrial control computer 33 will display the real-time curve of the signal acquired by the SERF atomic magnetometer, showing a pattern similar to... Figure 6 The periodic changes shown are such that the number of periods is equal to the number of detections; that is, one detection corresponds to one sampling period, and one sampling period includes multiple sampling points. Figure 6 The remanence of the material can be obtained by subtracting the minimum value from the maximum value in one cycle, in pT.

[0134] In the case of conducting magnetic noise testing:

[0135] Confirm that the extremely weak magnetic signal detection system is in mode 2. Turn the leftmost button at the start of the conveyor belt to the "automatic" position, and click the green "cycle start" button in the middle. The conveyor belt will then begin to move.

[0136] When the fixture 40 moves to directly below the probe of the SERF atomic magnetometer (point A), it will stop moving. At this time, wait for the SERF atomic magnetometer sensitivity data to be updated on the industrial control computer 33. Generally, the first set of data after the movement stops will be inaccurate due to the influence of material movement. Therefore, the sensitivity after the second update is used as the standard. Record the average sensitivity of 2-30Hz for this test, and subtract the average sensitivity data of 2-30Hz in the no-sampling state to obtain the magnetic noise of the material, in fT. After the inspection is completed, the material is unloaded.

[0137] The extremely weak magnetic signal detection system provided in this invention can independently select residual magnetism or magnetic noise testing as needed to perform batch automatic testing of the materials to be tested.

[0138] Figure 7 This is a flowchart of the detection method of the extremely weak magnetic signal detection system provided in the embodiments of the present invention.

[0139] See Figure 7 This invention provides a detection method for an extremely weak magnetic signal detection system based on any one of the above-mentioned methods, comprising the following steps:

[0140] Step S100: Fix the material to be tested onto the loading fixture 40 of the conveying component 23.

[0141] Understandably, the material to be tested can be placed in the sample positioning slot of the loading fixture 40, with the bottom in contact with the silicone pad. The side stop can be pushed to the side of the sample to be tested, and the stop can be initially fixed with bolts. The spring buckle can be closed, and it can be observed whether the material to be tested shakes.

[0142] Among them, the method of fixing the material to be tested should be selected according to the characteristics of the material to be tested, such as mechanical clamping or bonding. By using low magnetic susceptibility materials and precision positioning structures, the position of the material to be tested is ensured to be stable during the transmission and testing process, so as to provide a reliable guarantee for the acquisition of extremely weak magnetic signals.

[0143] Step S200: Drive the conveying component 23 to work, so that the material to be tested enters the shielding cavity of the magnetic shielding component 10.

[0144] Understandably, the control system sends a command, the drive component 22 starts, and the conveying component 23 sends the material to be tested into the shielded cavity at a constant speed until the material to be tested reaches the detection area.

[0145] Step S300: When it is determined that the material to be tested is located in the detection area of ​​the magnetometer (such as a SERF atomic magnetometer), the residual magnetism and magnetic noise of the material to be tested are collected and processed.

[0146] Understandably, the detection area of ​​magnetometer 31 is the spatial range where its sensitivity is highest; for example, the effective detection area of ​​the SERF atomic magnetometer is near the central axis. The location of this area needs to be determined through geometric calibration.

[0147] A second position detection element (such as a through-beam photoelectric sensor) is installed on the magnetically shielded component 10. When the material to be measured or the mounting fixture 40 blocks the light beam, the through-beam photoelectric sensor outputs a TTL low-level trigger signal (rising edge / falling edge) to indicate that the material to be measured is about to enter the detection area.

[0148] Alternatively, an incremental encoder can be installed at the end of the drive shaft of the drive assembly 22 to provide real-time feedback on the position of the material to be tested through pulse counting (e.g., each pulse corresponds to a displacement of 0.1 mm). When the encoder count reaches a preset value (e.g., 500 pulses correspond to x=0 mm), it is confirmed that the material to be tested has entered the detection area.

[0149] Figure 8 This is a detailed flowchart of the detection method of the extremely weak magnetic signal detection system provided in the embodiments of the present invention.

[0150] See Figure 8 In some embodiments of the present invention, in step S300 above, when it is determined that the material to be tested is located in the detection area of ​​the SERF atomic magnetometer, the remanence of the material to be tested is collected and processed, including:

[0151] Determine the movement of the material to be tested to the preset trigger position, record the trigger time corresponding to the preset trigger position, and record the running time of the material to be tested after it starts from the preset trigger position in real time;

[0152] When it is determined that the current position of the material to be tested is within the detection area of ​​the SERF atomic magnetometer at the current operating time, the material to be tested is controlled to perform reciprocating motion on the conveying component 23, and the magnetic induction intensity of the SERF atomic magnetometer is collected in real time during the reciprocating motion of the material to be tested, and a curve of the magnetic induction intensity changing periodically with the sampling point is generated.

[0153] The remanence of the material to be tested is determined by the curve showing the periodic change of magnetic induction intensity with the sampling point.

[0154] It is understandable that conveyor belts typically move at a constant linear speed, and their speed v can be pre-calibrated using parameters such as motor speed and transmission ratio. For example, the belt linear speed can be monitored in real time by an encoder, or the speed can be calculated using the pulse frequency of a stepper motor.

[0155] During the system debugging phase, it is necessary to calibrate the correspondence between each target position (point B, point A, and point C) on the conveyor belt and time. The specific method is as follows:

[0156] Determine the reference origin: Take a fixed reference point of the conveyor belt, such as the preset trigger position D, as the origin of the position coordinates x=0, and define the transmission direction as the positive direction.

[0157] Measure the physical distances between each location: Using tools such as a laser rangefinder and a mechanical ruler, measure the distances from point D to point B, from point B to point A, and from point A to point C, and record them as L. DB L BA L AC Total length L DC =L DB +L BA +L AC .

[0158] Calculate the "time threshold" for each location: Due to the uniform speed of the conveyor belt, the time required for the material to move from the preset trigger position to any location x is t(x) = x / v. Therefore, the time threshold corresponding to each critical location is:

[0159] Preset trigger position (origin): t D =0 (trigger time); Point B: t B =L DB / v; Point A: t A =(L DB +L BA ) / v; Point C: t C =L DC / v.

[0160] In actual operation, the following process is used to determine the location using time:

[0161] Triggering point (point D): When the material to be tested moves to the preset triggering position D along with the conveyor belt, the second position detection element (such as a photoelectric switch or proximity sensor) is triggered, and the system synchronously records the current time t. 触发 (e.g. t) D ).

[0162] With t D The trigger moment is taken as the starting point of time. The running time Δt=t of the material under test after it starts from point D is recorded in real time by a timing module (such as a PLC clock or a microcontroller timer). 当前 -t 触发 According to the formula for uniform motion This allows us to calculate the current position x of the material being measured at the current moment. For example:

[0163] When Δt=t B When the material reaches point B (x=L) DB );

[0164] When Δt=t C When the material reaches point C (x=L) DC ).

[0165] Once the material to be tested reaches point C (behind the probe), it begins its reciprocating motion. The reciprocating time can be directly controlled by a timer (e.g., if the reciprocating cycle T is set, then t...). 往返 =T), ensuring that the motion trajectory is synchronized with the probe signal acquisition.

[0166] In some embodiments of the present invention, when it is determined that the current position of the material to be tested is within the detection area of ​​the magnetometer at the current operating time, the material to be tested is controlled to perform reciprocating motion on the conveying assembly 23, including:

[0167] The current position of the material to be tested at the current operating moment is determined to be directly below the magnetometer (point A). This is equivalent to the material to be tested moving from point D to point A. Using point A as the determined position, the material to be tested is controlled to run on the conveyor component 23 for a first preset time period, which is equivalent to the material to be tested needing to move from point A to point C.

[0168] When it is determined that the material to be tested has traveled on the conveyor component 23 for a first preset time period, which is equivalent to determining that the material to be tested has moved to point C, the material to be tested is controlled to travel in the opposite direction on the conveyor component 23 for a second preset time period. This is equivalent to the material to be tested moving from point C to point B, and then making multiple round trips between points B and C. The second preset time period is equal to twice the first preset time period. Since the speed of the material to be tested is constant, the distance between points B and C is equal to twice the distance between points A and C, i.e., L. BC =L BA +L AC =2×L AC .

[0169] Specifically, after the probe of the SERF atomic magnetometer is started up to a stable working state, the material to be measured is placed at a fixed distance from the probe of the SERF atomic magnetometer and moved perpendicular to the sensitive axis. Since the single-beam SERF atomic magnetometer is in zero-field resonance, the relationship between the response signal and the magnetic field magnitude can be simplified to the following equation (1):

[0170] (1);

[0171] in, For the response coefficient, For optical pumping rate, The horizontal relaxation rate. Where is the free electron gyromagnetic ratio, and Bx is the component of the magnetic field vector in the x-direction.

[0172] As shown in equation (1), when all other conditions of the single-beam SERF atomic magnetometer remain constant, the response signal is linearly related to the magnitude of the magnetic field. When the test material is placed in, it will cause a change in the amplitude of the probe response signal of the SERF atomic magnetometer. However, since the probe cannot be in an absolutely zero magnetic environment after magnetic shielding, remanent magnetization compensation will be performed when the SERF atomic magnetometer is ready to run. Therefore, in order to avoid inaccurate measurement data due to the remanent magnetization being compensated after the test material is placed in, the test material is moved to the area below the probe of the SERF atomic magnetometer and then moves back and forth. The difference between the maximum peak value and the minimum peak value of the response signal after conversion into the magnetic field magnitude is taken as the magnitude of the remanent magnetization introduced by the test material.

[0173] like Figure 5 As shown, the conveying component is placed in the magnetic shielding barrel 12. During the residual magnetism test, the material to be tested will be conveyed to point C, and then move back and forth between points B and C (points B and C are almost symmetrical about point A). After the test, it will be conveyed out of the magnetic shielding barrel 12 and return to the starting point. The magnitude of the residual magnetism can be expressed by the following formula (2):

[0174] (2);

[0175] Where B_max avg B_min is the average value of the maximum magnetic field response during the round-trip motion. avg It is the average value of the minimum magnetic field response during the round-trip motion.

[0176] Continue reading Figure 6 Furthermore, based on the curve showing the periodic variation of magnetic induction intensity with sampling points, the remanence of the material to be tested is determined, including:

[0177] Select any complete period from the curve of the periodic change of magnetic induction intensity with the sampling point as the target period; determine the maximum and minimum values ​​of magnetic induction intensity within the target period, and the difference between the maximum and minimum values ​​is the remanence of the material to be tested.

[0178] Understandably, the specific steps are as follows:

[0179] Step 1: Equipment Operation. Confirm that the detection system is in Mode 1. Turn the leftmost button at the start of the conveyor belt to the "Automatic" position, and click the green "Cycle Start" button in the middle. The conveyor belt will then begin to move.

[0180] Step 2: When the material to be tested moves to... Figure 5 At point A, the reciprocating motion will begin, and the industrial control computer will display the real-time curve of the signal acquired by the SERF atomic magnetometer, showing a pattern similar to... Figure 6 The periodic changes shown are equal in number to the number of detections. The remanence of the material can be obtained by subtracting the minimum value from the maximum value of one period in the figure, in pT.

[0181] Continue reading Figure 6 In some embodiments of the present invention, in step S300 above, when it is determined that the material to be tested is located in the detection area of ​​the magnetometer, the magnetic noise of the material to be tested is collected and processed, including:

[0182] Obtain the first average sensitivity value of the magnetometer under no-load conditions. The no-load conditions refer to the background sensitivity data collected by the magnetometer in the frequency range of 2-30Hz when the loading fixture is not carrying the material to be measured.

[0183] Determine the movement of the material to be tested to the preset trigger position, record the trigger time corresponding to the preset trigger position, and record the running time of the material to be tested after it starts from the preset trigger position in real time.

[0184] When it is determined that the current position of the material to be tested is directly below the magnetometer at the current operating moment, the material to be tested is controlled to stop moving, and the updated sensitivity data of the magnetometer is recorded.

[0185] The magnetic noise of the material to be measured is determined by the difference between the second average sensitivity value in the 2-30Hz frequency range of the non-first updated sensitivity data and the first average sensitivity value of the magnetometer under no-load conditions.

[0186] like Figure 5 As shown, during the magnetic noise test, the material to be tested is transported to point A (directly below mounting bracket 233), remains stationary for a period of time, and then is transported out of the magnetic shielding barrel 12 and returned to the starting point. The magnitude of the magnetic noise is determined by the influence of the material to be tested on the sensitivity of the SERF atomic magnetometer. The magnitude of the magnetic noise can be expressed by the following formula (3):

[0187] (3);

[0188] Among them, S 样品 It is the average sensitivity of the SERF atomic magnetometer after the material (sample) to be measured moves directly below it, S 空采 It is the average sensitivity of the SERF atomic magnetometer during air sampling.

[0189] Essentially, the first step is equipment operation. Confirm that the detection system is in mode 2. Turn the leftmost button at the start of the conveyor belt to the "automatic" position, and click the green "cycle start" button in the middle. The conveyor belt will then begin to move.

[0190] Step 2: The material to be tested is placed on the loading fixture (outside the shielded cavity) at the initial end of the conveying component. Then, the control system sends a command to start the component, and the conveying component uniformly feeds the material to be tested into the shielded cavity. When the loading fixture moves to directly below the probe (point A), it will stop moving and wait for 2-3 seconds (the SERF atomic magnetometer preheats and stabilizes). The industrial control computer then begins to collect magnetometer data. The first update data is marked as invalid due to residual vibration interference from sample movement. The average sensitivity (2-30Hz) of the second update is recorded. Using the sensitivity after the second update as the standard, the average sensitivity of 2-30Hz for this update is recorded. Subtracting the average sensitivity data of 2-30Hz from the no-sample state yields the magnetic noise of the material, in fT. .

[0191] By differentially calculating the sample detection signal and the background signal from the air sample, environmental noise (such as geomagnetic field fluctuations and thermal noise from electronic devices) is subtracted, retaining only the residual magnetism or magnetic noise of the sample itself. The control system eliminates transient interferences (such as mechanical vibration reverberation) during sample movement through a "second data update," ensuring data validity.

[0192] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for detecting extremely weak magnetic signals, characterized in that, include: The magnetic shielding component has an internal shielding cavity. The conveying component includes: The support frame is located on one side of the magnetic shielding component and is disposed away from the shielding cavity; The drive assembly is located on the support frame. A transmission component is provided on the support frame. One end of the transmission component is in transmission cooperation with the drive component, and the other end passes through the magnetic shielding component and extends into the shielding cavity. Detection components, including: A magnetometer is fixedly mounted on the conveying assembly that extends into the shielded cavity. The detection point of the magnetometer is located in the uniform region of the magnetic field inside the shielded cavity, and is used to detect residual magnetism and magnetic noise in the material to be tested. The control system is located on one side of the magnetic shielding component and is disposed away from the shielding cavity. The control system is electrically connected to the magnetometer and the drive assembly respectively, and is used to collect and process the detection signal of the magnetometer and to control the operation of the drive assembly. The control system is further configured to: control the transmission component to perform reciprocating motion within the detection area of ​​the magnetometer, and determine the remanence of the material to be tested based on the peak-to-peak value of the periodically changing magnetic induction intensity signal collected during the reciprocating motion.

2. The extremely weak magnetic signal detection system according to claim 1, characterized in that, The transmission component includes: A support unit is provided on the support frame, the support unit is provided with a rotatable transmission shaft, and the support unit is provided with a mounting bracket at a position away from the drive component; A conveying unit is arranged around the drive shaft, and a loading fixture is provided on the conveying unit; The magnetometer is mounted on the mounting bracket, and the material to be measured is placed on the loading fixture.

3. The extremely weak magnetic signal detection system according to claim 1, characterized in that, It also includes a first position detection element and a second position detection element, both of which are electrically connected to the control system; The first position detection element is located near the support frame of the conveying assembly and is used to detect the starting position of the material to be tested; The second position detection element is located on the magnetic shielding component and is used to detect the preset trigger position of the material to be tested within the shielding cavity.

4. The extremely weak magnetic signal detection system according to any one of claims 1 to 3, characterized in that, The control system includes: A data acquisition component, electrically connected to the magnetometer, is used to acquire the detection signal of the magnetometer; The industrial control computer is equipped with a control module and a signal processing and analysis module. The control module is electrically connected to the drive component and is used to control the operation of the drive component. The signal processing and analysis module is electrically connected to the data acquisition component and is used to analyze the acquired detection signals and output the detection results.

5. The extremely weak magnetic signal detection system according to any one of claims 1 to 3, characterized in that, The magnetic shielding component includes: Vibration isolation platform; A magnetic shielding barrel is disposed on the vibration isolation platform, and the magnetic shielding barrel forms the shielding cavity, wherein the residual magnetism in the shielding cavity is less than 1nT; The magnetic shielding barrel has at least one opening, and a shielding cover is provided at the position of at least one of the openings. The conveying component passes through the opening.

6. A detection method based on the extremely weak magnetic signal detection system according to any one of claims 1 to 5, characterized in that, Includes the following steps: The material to be tested is fixed on the loading fixture of the conveying assembly; Drive the conveying component to operate, so that the material to be tested enters the shielding cavity of the magnetic shielding component; When the material to be tested is located in the detection area of ​​the magnetometer, the residual magnetism and magnetic noise of the material to be tested are collected and processed.

7. The detection method of the extremely weak magnetic signal detection system according to claim 6, characterized in that, When determining that the material to be tested is located in the detection area of ​​the magnetometer, the remanent magnetism of the material to be tested is collected and processed, including: Determine that the material to be tested has moved to a preset trigger position, record the trigger time corresponding to the preset trigger position, and record the running time of the material to be tested after it starts from the preset trigger position in real time; When it is determined that the current position of the material to be tested is within the detection area of ​​the magnetometer at the current operating time, the material to be tested is controlled to perform reciprocating motion on the conveying component, and the magnetic induction intensity of the magnetometer is collected in real time during the reciprocating motion of the material to be tested, and a curve of the magnetic induction intensity changing periodically with the sampling point is generated. The remanence of the material to be tested is determined by the curve showing the periodic change of magnetic induction intensity with the sampling point.

8. The detection method of the extremely weak magnetic signal detection system according to claim 7, characterized in that, When it is determined that the current position of the material to be tested is within the detection area of ​​the magnetometer at the current operating time, controlling the material to be tested to perform reciprocating motion on the conveying assembly includes: The current position of the material to be tested at the current operating time is determined to be directly below the magnetometer, and the material to be tested is controlled to run on the conveying component for a first preset time period. When the material to be tested is determined to run on the conveying component for a first preset time period, the material to be tested is controlled to run in reverse on the conveying component for a second preset time period, wherein the second preset time period is equal to twice the first preset time period.

9. The detection method of the extremely weak magnetic signal detection system according to claim 7, characterized in that, The determination of the remanence of the material to be tested based on the curve of periodic variation of magnetic induction intensity with sampling points includes: Select any complete period from the curve of the periodic change of magnetic induction intensity with the sampling point as the target period; The difference between the maximum and minimum values ​​of magnetic induction intensity within the target period is determined, and the difference is the remanence of the material to be tested.

10. The detection method of the extremely weak magnetic signal detection system according to claim 6, characterized in that, When determining that the material to be tested is located within the detection area of ​​the magnetometer, the magnetic noise of the material to be tested is collected and processed, including: The first average sensitivity value of the magnetometer under no-load conditions is obtained, wherein the no-load conditions refer to the background sensitivity data collected by the magnetometer in the frequency range of 2-30Hz when the loading fixture is not carrying the material to be measured. Determine that the material to be tested has moved to a preset trigger position, record the trigger time corresponding to the preset trigger position, and record the running time of the material to be tested after it starts from the preset trigger position in real time; When it is determined that the current position of the material to be tested is directly below the magnetometer at the current operating time, the material to be tested is controlled to stop moving, and the updated sensitivity data of the magnetometer is recorded. The magnetic noise of the material to be tested is determined by the difference between the second average sensitivity value in the 2-30Hz frequency range of the non-first updated sensitivity data and the first average sensitivity value of the magnetometer under no-load conditions.

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