WO2022022690A1 - 用于磁力计的校准系统和方法 - Google Patents

用于磁力计的校准系统和方法 Download PDF

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Publication number
WO2022022690A1
WO2022022690A1 PCT/CN2021/109654 CN2021109654W WO2022022690A1 WO 2022022690 A1 WO2022022690 A1 WO 2022022690A1 CN 2021109654 W CN2021109654 W CN 2021109654W WO 2022022690 A1 WO2022022690 A1 WO 2022022690A1
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Prior art keywords
magnetometer
magnetic field
calibration
value
measured
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PCT/CN2021/109654
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English (en)
French (fr)
Inventor
王帆
卓彦
杨思嘉
吴顺子
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Cognitive Medical Imaging Ltd
Institute of Biophysics of CAS
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Cognitive Medical Imaging Ltd
Institute of Biophysics of CAS
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Priority to US18/018,735 priority Critical patent/US12196834B2/en
Priority to EP21849544.8A priority patent/EP4191268A4/en
Publication of WO2022022690A1 publication Critical patent/WO2022022690A1/zh
Anticipated expiration legal-status Critical
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
    • G01R35/005—Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/6802—Sensor mounted on worn items
    • A61B5/6803—Head-worn items, e.g. helmets, masks, headphones or goggles
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/0017—Means for compensating offset magnetic fields or the magnetic flux to be measured; Means for generating calibration magnetic fields
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/0023—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration
    • G01R33/0035—Calibration of single magnetic sensors, e.g. integrated calibration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/0094—Sensor arrays
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/24—Arrangements or instruments for measuring magnetic variables involving magnetic resonance for measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/26—Arrangements or instruments for measuring magnetic variables involving magnetic resonance for measuring direction or magnitude of magnetic fields or magnetic flux using optical pumping
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/242—Detecting biomagnetic fields, e.g. magnetic fields produced by bioelectric currents
    • A61B5/245—Detecting biomagnetic fields, e.g. magnetic fields produced by bioelectric currents specially adapted for magnetoencephalographic [MEG] signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/0023—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration
    • G01R33/0041—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration using feed-back or modulation techniques

Definitions

  • the present invention relates to a calibration system and method for a magnetometer, as well as a magnetic detection system and a magnetic detection method, and also relates to a magnetometer support.
  • a magnetic detector in MEG technology with a superconducting quantum interference device (SQUID) as the core device needs to periodically (for example, by placing a model that generates a known magnetic field strength) for detector gain value detection and Perform calibration.
  • SQUID superconducting quantum interference device
  • the new optically pumped atomic magnetometer based on spin-exchange relaxation-free effect has a measurement accuracy that reaches or even exceeds the level that can be achieved by a SQUID magnetometer, and can work in a non-ultra-low temperature environment without liquid helium cooling and is small in size. Lightweight, enabling low-cost mass production through semiconductor processes. Since the intensity of the magnetic field detected by the magnetometer based on the SERF effect is calculated from the intensity or polarization angle of the polarized beam detected by the photoelectric sensor, in the field of weak magnetic detection based on the atomic magnetometer, in order to obtain accurate detection results, it is necessary to measure the detector ( The detection gain value of the magnetometer) is calibrated and calibrated.
  • the accurate calibration of the detector gain value is very important for accurate traceability positioning.
  • Existing atomic magnetometers use coils in each detector close to the gas chamber to generate a magnetic field of a specific strength during detector startup to calibrate the detector's gain. This method is difficult to perform accurate simultaneous calibration and collaborative calibration of multiple detectors in a working environment with certain external magnetic field changes.
  • the present invention proposes a calibration system and method for a magnetometer, using a method for calibrating a magnetic field signal source that can act on all detectors at the same time, performing collaborative calibration of multiple detectors and using it as a reference signal It can continuously calibrate the gain value of the detector during the recording process, so as to obtain accurate multi-detector magnetic field recording and traceability positioning results.
  • Embodiments of the present invention provide a calibration system for a magnetometer, including a magnetometer configured to measure a magnetic field to be measured; a magnetometer bracket on which the magnetometer is fixedly mounted so that the magnetic force a known spatial position and orientation of the magnetometer; at least one magnetic field generating device, fixed in position relative to the magnetometer, for generating a calibrated magnetic field distribution in the space to be measured; and a computing device configured according to calculating the magnitude of the magnetic field vector at the location where the magnetometer is located from the calibrated magnetic field distribution generated by the at least one magnetic field generating device in the space to be measured, receiving the magnitude of the magnetic field vector measured by the magnetometer from the magnetometer, and A detection gain value of the magnetometer is calculated based on the magnitude of the magnetic field vector obtained by the calculation and the magnitude of the measured magnetic field vector.
  • Embodiments of the present invention provide a method for calibrating a magnetometer, including providing a magnetometer mounted on a magnetometer bracket, the magnetometer being configured to measure the magnitude of the magnetic field at the location where the magnetometer is located, as the measurement value of the magnetometer ; fixing the position of at least one magnetic field generating device relative to the magnetometer, the at least one magnetic field generating device being configured to generate a calibration magnetic field distribution; determining the spatial position and orientation of the magnetometer, and based on the spatial position and orientation of the magnetometer and Calibrate the magnetic field distribution, and calculate the calibration actual value of the magnetic field at the location where the magnetometer is located; measure the calibration measurement value of the magnetic field at the location where the magnetometer is located; based on the calibration measurement value and the calibration actual value, calculate the The detection gain value of the magnetometer.
  • Embodiments of the present invention provide a method for calibrating a magnetometer, including providing a magnetometer mounted on a magnetometer bracket, the magnetometer being configured to measure the magnitude of the magnetic field at the location where the magnetometer is located, as the measurement value of the magnetometer ; providing a plurality of magnetic field generating devices, at least a part of the magnetic field generating devices in the plurality of magnetic field generating devices is fixedly arranged on the magnetometer, the at least a part of the magnetic field generating devices is configured to generate a calibration magnetic field; measuring the calibration by the magnetometer The calibration measurement value of the magnetic field; based on the calibration magnetic field and the calibration measurement value, calculate the detection gain value of the magnetometer; generate a fixed or regular change with the known parameters through another part of the magnetic field generating device located on the magnetometer bracket For the magnetic field, the gain value of the magnetometer is calibrated by measuring the measured value of the magnetic field generated by the magnetic field generating device and the change of the measured value during the recording process by the magnetometer for calibrating the gain.
  • Embodiments of the present invention provide a magnetic detection system, including a magnetometer support; a magnetometer, the magnetometer is mounted on the magnetometer support and measures the magnitude of the magnetic field vector at the location as the measurement value of the magnetometer; a device, the magnetic field generating device is disposed at a predetermined position and generates a calibration magnetic field distribution; and a computing device is configured to calculate the magnetic field distribution of the magnetometer based on the spatial position and orientation of the magnetometer and the calibration magnetic field distribution a calibrated actual value of the magnetic field vector at the location at , receiving a calibrated measurement of the magnetic field vector measured by the magnetometer, and comparing the calibrated actual value with the calibrated measurement to calculate a detection gain value for the magnetometer .
  • An embodiment of the present invention is a magnetic detection system, comprising a magnetometer bracket; a magnetometer, the magnetometer is installed on the magnetometer bracket and measures the magnitude of the magnetic field vector at the position as the measurement value of the magnetometer; a first magnetic field a generating device, the first magnetic field generating device being disposed at a predetermined location and generating a calibration magnetic field; and a computing device configured to receive calibration measurements of the calibration magnetic field measured by the magnetometer, and based on the calibration magnetic field and the calibration measurements, a detection gain value for the magnetometer is calculated.
  • Embodiments of the present invention provide a magnetic detection method, including providing a magnetometer, which is mounted on a magnetometer stand and measures the magnitude of the magnetic field vector at its location as a measurement value of the magnetometer; using the above-mentioned
  • the detection gain value of the magnetometer is obtained by the calibration method according to the invention; the magnetic field to be measured is measured by the magnetometer; and the measurement result of the magnetometer is multiplied by the detection gain value to obtain the actual value of the magnetic field to be measured.
  • Embodiments of the present invention provide a magnetometer stand, comprising a mounting portion for mounting a magnetometer; and at least one magnetic field generating device, fixed in position relative to the magnetometer, for generating a calibration magnetic field.
  • FIG. 1 shows a schematic diagram of a calibration system according to an embodiment of the present invention
  • Figure 2 shows a schematic diagram of a calibration system according to yet another embodiment of the present invention.
  • FIG. 3 shows a schematic diagram of a calibration system according to yet another embodiment of the present invention.
  • Figure 4 shows a schematic diagram of a calibration system according to a variant embodiment of the invention
  • FIG. 5 shows a schematic diagram of the spatial distribution of the calibration magnetic field generated by the magnetic field generating device according to an embodiment of the present invention
  • Fig. 6 shows the distribution diagram of the measured value of the magnetic field strength in the frequency domain obtained by the computing device of the embodiment shown in Fig. 1;
  • FIG. 7 shows a flowchart of a calibration method for a magnetometer according to an embodiment of the present invention
  • FIG. 8 shows a flowchart of a calibration method for a magnetometer according to yet another embodiment of the present invention.
  • FIG. 9 shows a flowchart of a calibration method for a magnetometer according to yet another embodiment of the present invention.
  • FIG. 10 shows a schematic diagram of a magnetometer stand according to an embodiment of the present invention.
  • FIG. 11 shows a schematic block diagram of a magnetic detection system according to an embodiment of the present invention.
  • FIG. 12 shows a flowchart of a magnetic detection method according to an embodiment of the present invention.
  • magnetometer optically pumped atomic magnetometer based on the SERF effect
  • the detection process is related to the influence of the external magnetic field, and the gain value of the detector is not only related to the detector.
  • the hardware itself is related to the control parameters, and it is also affected by the net magnetic field at the location of the detector. Even in the non-sensitive direction of the detector, such as the magnetic field along the incident direction of the detection beam, it will affect the detection gain of the detector in the sensitive direction.
  • This characteristic is very different from traditional SQUID sensitive detectors whose gain values are basically stable under different external magnetic fields. It is used in traditional SQUID detector array calibration methods, such as periodic Heat engine maintenance or routine maintenance cycle of each equipment) to place a model that generates a known magnetic field strength for detection and calibration of detector gain values, which cannot be applied to optical pump atomic magnetometers.
  • the position, pointing and gain of the detectors are crucial for accurate traceability localization.
  • Existing optically pumped atomic magnetometers use a coil in each detector near the gas chamber to generate a magnetic field of a specific strength during the start-up process of the detector to calibrate the detector gain. For a single detector, this approach is efficient and feasible.
  • the magnetic field generated by the calibration coil will cause crosstalk between the detectors. When a detector is calibrated, the magnetic field generated by it will affect other adjacent detectors.
  • the existing device cannot perform synchronous calibration of all detectors at the same time, and can only perform calibration by calibrating each detector in sequence or by performing interval calibration of detectors separated by a certain distance. Not only does this significantly increase the time required for calibration, but it is not possible to accurately calibrate all detectors when there are changes in the external magnetic field.
  • the multi-detector system composed of existing detectors cannot perform continuous or certain interval continuous calibration, and it is difficult to perform accurate multi-detector simultaneous recording and signal traceability positioning.
  • the present invention uses a system and method for calibrating based on an external magnetic field signal source, performs collaborative calibration of multiple detectors and can use it as a reference signal source to continuously calibrate the gain value of the detector during the recording process, thereby obtaining Accurate multi-detector magnetic field recording results.
  • optical-pumped atomic magnetometer refers to optically-pumped atomic magnetometers based on spin-exchange-free relaxation effect (SERF) .
  • SESF spin-exchange-free relaxation effect
  • FIG. 1 shows a schematic diagram of a calibration system according to an embodiment of the present invention.
  • Figure 2 shows a schematic diagram of a calibration system according to yet another embodiment of the present invention.
  • Figure 3 shows a schematic diagram of a calibration system according to yet another embodiment of the present invention.
  • Figure 4 shows a schematic diagram of a calibration system according to a variant embodiment of the invention.
  • Embodiments of the present invention provide a calibration system for a magnetometer, comprising: a magnetometer configured to measure a magnetic field to be measured; a magnetometer bracket on which the magnetometer is mounted; at least one magnetic field generating device , which is fixed in position relative to the magnetometer for generating a calibration magnetic field; and a computing device for obtaining the measurement results of the magnetometer.
  • the magnetometer is configured to measure a calibration magnetic field generated by at least one magnetic field generating device, and the computing device calculates a probe gain value for the magnetometer based on the magnetometer measurements.
  • At least one magnetic field generating device may be disposed on at least one of the magnetometer support, the space to be measured, or the magnetometer.
  • the calibration magnetic field generated by the magnetic field generating device is known, so the magnetic field distribution of the calibration magnetic field at the location of the magnetometer is known, and the detection gain value of the magnetometer can be calculated based on the measurement results of the magnetometer and the magnetic field distribution .
  • the calibration system of the present invention Compared with each magnetometer using its own signal source for calibration, the calibration system of the present invention has the advantage that there will be no crosstalk with the existing magnetometer during calibration, so that the work of other detectors will not be affected. In addition, simultaneous calibration can be performed quickly, and even continuous calibration and continuous calibration can be performed while the magnetometer is recording.
  • the calibration system of the present invention can expand the detection dynamic range of the magnetometer to the non-linear region of the detector without sacrificing sensitivity, thereby expanding the detection range.
  • the calibration system includes a magnetometer 1 , a magnetometer holder 2 , at least one magnetic field generating device 3 and a computing device 4 .
  • the magnetic field generating device 3 can be configured to generate a known or preset calibration magnetic field distribution, the known or preset calibration magnetic field distribution refers to a magnetic field distribution that can be calculated according to the input or other parameters of the magnetic field generating device 3 or can be obtained by The magnetic field distribution obtained in other ways is used to calibrate the detection gain value of the magnetometer 1 . Through the magnetic field distribution, the magnitude of the magnetic field vector at a certain spatial position and orientation in the magnetic field distribution can be obtained.
  • the magnetometer 1 is configured to measure the magnetic field to be measured in the space to be measured, such as the brain magnetic signal of a subject.
  • the magnetometer 1 can also be used to obtain information related to the biomagnetic field of other parts, depending on where the magnetometer 1 is set.
  • the magnetometer mount 2 is in the form of a helmet, which can be fixedly positioned relative to the space to be measured (eg, the subject's head), and includes at least one mounting portion (not shown) having a predetermined orientation ), allowing the magnetometers 1 to be respectively disposed on the mounting portion at a first depth along a specific direction.
  • the magnetometer bracket 2 includes a plurality of installation parts, and the magnetometer 1 is respectively installed on each installation part and fixed relative to the magnetometer bracket.
  • each mounting portion for example, in the case where the mounting portion is a mounting hole, knowing the axial spatial direction of the mounting hole and the depth to which the magnetometer 1 is inserted into the mounting hole, it is possible to determine Spatial position and orientation information of magnetometer 1.
  • the magnetometer 1 is fixedly mounted on the magnetometer bracket 2, so once the installation is completed, the relative position and orientation between the magnetometer 1 and the mounting hole can be fixed and determined.
  • the installation part may include, for example, a detection electrode, and through the detection electrode, it can be detected that the magnetometer has been installed in the installation hole and the installation depth of the magnetometer.
  • the installation part may be provided with a sensor to sense the installation information of the magnetometer, such as the installation depth of the magnetometer, and the identification code of the magnetometer, and use the installation information of the magnetometer, such as, The installation depth of the magnetometer, the identification code of the magnetometer, and the specific information of the installation part on which the magnetometer is installed, such as the spatial orientation of the installation part, are sent to the computing device, whereby the computing device can obtain the spatial position and Orientation information.
  • the detector of the magnetometer 1 is a vector detector, and the detected magnetic field information is vector information, which is different from the traditional EEG detection that only detects electrode scalar signals. Therefore, it is necessary to measure the magnetic field vector information detected by the detector. Also, the detector of the magnetometer 1 may be arranged to detect the magnetic field strength along the longitudinal axis direction (length direction) of the magnetometer 1 .
  • the "space to be measured” described in the present disclosure includes but is not limited to: the subject's head, abdomen or other body parts, and other objects that can detect the strength of the magnetic field, and those skilled in the art can make adaptive adjustments according to the actual measurement application. choice, which is not limited by the present disclosure.
  • the calibration system includes a plurality of magnetic field generating devices 3 , which are respectively arranged at different spatial positions fixed relative to the magnetometer 1 .
  • a plurality of magnetic field generating devices 3 may be disposed on at least one of the magnetometer support 2 , the space to be measured, or the magnetometer 1 .
  • the calibration system includes four magnetic field generating devices 3 , which are respectively arranged at four different spatial positions of the magnetometer support 2 , for example, three magnetic field generating devices 3 are located in the magnetometer bracket 2 shown in FIG. 1 .
  • another magnetic field generating device 3 is located just above the top of the magnetometer holder 2 .
  • the magnetic field generating device 3 can also be arranged at other spatial positions of the magnetometer support 2, as long as the position and orientation relative to the magnetometer are guaranteed to be fixed, and the number of the magnetic field generating devices 3 can also be based on actual needs. increase or decrease.
  • the computing device 4 is connected to the magnetometer 1 and the magnetic field generating device 3 by means of wired or wireless communication (indicated by dotted lines in the figure).
  • the computing device 4 may adopt computing equipment common in the art, including but not limited to: CPU, DSP, computer, workstation, and the like.
  • the magnetic field generating device 3 may be a coil loop or a dipole immersed in a conductive solution.
  • the magnetic field generating device 3 is a coil loop composed of an excitation coil, which can generate a spatial magnetic field when energized, as shown in FIG.
  • the magnetic field distribution of the magnetic field generating device 3 in the space can be obtained by calculating the parameters such as the number of turns of the coil, and the magnitude and direction of the magnetic field vector at a specific position in the space can be calculated from this.
  • the magnetic field generating device 3 can also be a dipole immersed in a conductive solution.
  • the calibration system may further include a calibration device for calibrating the calibration magnetic field generated by the magnetic field generating device.
  • the calibration device may be provided on or near the magnetic field generating device 3 to achieve continuous calibration, or may be provided separately and perform calibration of the magnetic field generating device 3 each time the magnetic field generating device 3 needs to be calibrated.
  • the frequency range of the calibration magnetic field generated by the magnetic field generating device 3 is set to be outside the frequency range of the magnetic field to be measured.
  • the frequency range of the calibration magnetic field generated by the magnetic field generating device 3 is larger than the frequency range of the magnetic field to be measured, which can prevent crosstalk of the detection results.
  • the frequency range of the magnetic field to be measured eg, the magnetic brain signal
  • the frequency range of the calibration magnetic field distribution generated by the magnetic field generating device 3 is in the range of 80 Hz to 200 Hz.
  • the frequency range of the calibration magnetic field generated by the magnetic field generating device 3 may be greater than 80 Hz, such as 80-100 Hz, 80-120 Hz, 100-200 Hz or greater than 200 Hz.
  • the frequency range of the calibration magnetic field generated by the magnetic field generating device 3 may also be smaller than the frequency range of the magnetic field to be measured, for example, smaller than 40 Hz.
  • the frequencies of the calibration magnetic field distributions generated by each of the plurality of magnetic field generating devices 3 are different, so different magnetic field generating devices 3 can be distinguished in the frequency domain.
  • the calibration system further includes a time-to-frequency domain converter (not shown) configured to convert the time-domain signal measured by the magnetometer into a frequency-domain signal through a Fourier transform or other algorithm , the target measurement corresponding to the magnetometer is calculated from the calibration measurement corresponding to the frequency of the calibration magnetic field.
  • the magnetometer domain signal converted by the converter is converted into a frequency domain signal as shown in FIG. 6 , for example, the signals of different frequencies each have peaks in the frequency domain.
  • the time-to-frequency domain converter can be a stand-alone converter chip, or an algorithm built into the computing device.
  • FIG. 6 shows a distribution diagram of the measured value of the magnetic field strength in the frequency domain obtained by the computing device of the embodiment shown in FIG. 1 .
  • the result of FIG. 6 is a measured value of the magnetic field strength calculated for one of the magnetometers 1 by the computing device.
  • the four magnetic field generating devices 3 are respectively excited at different frequencies, so that the frequencies of the calibration magnetic fields generated by each magnetic field generating device 3 are different, for example, 173 Hz, 178 Hz, 183 Hz, and 188 Hz.
  • the magnetic field strengths generated by the four magnetic field generating devices 3 have four peaks in the frequency domain, and the measured values are shown in FIG. 6 , which are M 1 , M 2 , M 3 and M 4 respectively.
  • FIG. 6 which are M 1 , M 2 , M 3 and M 4 respectively.
  • FIG. 6 shows a schematic diagram of a calibration system according to yet another embodiment of the present disclosure. The difference from the embodiment shown in FIG. 1 is that this embodiment adopts a larger size magnetic field generating device 31 , so that a more uniformly distributed calibration magnetic field can be formed in space, which is convenient for calibration.
  • FIG. 3 shows a schematic diagram of a calibration system according to yet another embodiment of the present disclosure.
  • the magnetic field generating device 32 of this embodiment is fixedly arranged on at least one of the plurality of magnetometers, for example, three, as shown in FIG. 3 .
  • the magnetic field generating device may also have other arrangements according to calibration requirements.
  • the first magnetic field generating device 33 can be fixedly disposed on each magnetometer 1, and at least one second magnetic field generating device 34 can also be fixedly disposed on the magnetometer support 2, for example, two second magnetic field generating devices 34, such as shown in Figure 4.
  • FIG. 5 shows a schematic diagram of the spatial distribution of the calibration magnetic field generated by the magnetic field generating device according to an embodiment of the present invention.
  • FIG. 7 shows a flowchart of a calibration method for a magnetometer according to an embodiment of the present invention.
  • the calibration method includes the following steps:
  • S10 Provide a magnetometer installed on the magnetometer bracket, where the magnetometer is configured to measure the magnitude of the magnetic field at the location where the magnetometer is located, as a measurement value of the magnetometer.
  • At least one magnetic field generating device Provides at least one magnetic field generating device, where the position of the at least one magnetic field generating device is fixed relative to the magnetometer, and the at least one magnetic field generating device generates a known or predetermined spatial magnetic field distribution.
  • the magnetometer 1 and the magnetometer support 2 in step S10 can be arranged in, for example, the embodiments shown in FIGS. 1-3 , and details are not described herein again.
  • the magnetic field generating device 3 may adopt the magnetic field generating device of the foregoing embodiment.
  • the magnetic field generating device 3 is turned on to generate a calibration magnetic field, and the calibration magnetic field will form a spatial magnetic field distribution, as shown in FIG. 5 .
  • the parameters of the calibration magnetic field distribution can be obtained by pre-calibration, and calculated and simulated by Maxwell's equations and Jefimenko's equations based on Maxwell's equations
  • the spatial magnetic field distribution of the calibration magnetic field can be simulated. In practical calculations, it is usually possible to use the Biot-Savart Law (Biot-Savart Law) under the approximation condition of the quasi-static limit:
  • ⁇ 0 is the vacuum permeability
  • I is the source current
  • L is the integral path
  • dl is the tiny line element of the source current r
  • This simulation step can also be implemented in the computing device 4 . Based on the spatial magnetic field distribution, the magnitude of the magnetic field vector at any point in space can be calculated.
  • step S30 as long as the position of any magnetometer 1 in space is known, the magnitude of the actual value M 0 of the calibration magnetic field at the position of the magnetometer 1 can be obtained. While determining the spatial position of the magnetometer 1 may adopt various methods, which will be described further below.
  • step S40 the magnetometer 1 measures the magnetic field size of the calibration magnetic field at the position where the magnetometer 1 is located to obtain the calibration measurement value M A .
  • step S50 the detection gain value is calculated by the calculation device 4 based on the calibration measurement value MA and the calculated calibration actual value M0 .
  • This detection gain value can be used to calibrate the difference between the measured value of the magnetometer 1 and the actual value.
  • the detection gain value may include the detection gain value K of the magnetometer.
  • the detection gain value K is obtained by dividing the actual value M 0 of the calibration magnetic field by the calibration measurement value M A , namely:
  • the magnetometer 1 can be calibrated. For example, when the magnetometer 1 is actually working, the actual magnetic field magnitude signal value can be obtained by multiplying the magnetic field magnitude signal detected by the magnetometer 1, that is, the target measurement value by the detection gain value K. In practical applications, it is also possible that the gain response of the detector at different frequencies is a nonlinear relationship, and the gain values of different frequencies can be calculated by pre-calibrated detection gain values.
  • FIG. 5 The calibration method of the present disclosure is described by taking FIG. 5 as an example.
  • the embodiment shown in FIG. 5 is only exemplary. Those skilled in the art can make variations and modifications on the basis of the principle of FIG. 5, which are still within the protection scope of the present disclosure. .
  • Figure 5 shows two magnetometers, a first magnetometer 1 and a second magnetometer 1'.
  • the first magnetometer 1 includes a detector 11 accommodated therein
  • the second magnetometer 1 ′ includes a detector 11 ′ accommodated therein
  • the detector 11 and the detector 11 ′ are the components that the magnetometer actually detects the size of the magnetic field, therefore
  • the positions of the detector 11 and the detector 11 ′ can be used as the positions of the magnetometer for calibration, and the preset magnetic field distribution can also be calculated based on the positions of the detector 11 and the detector 11 ′.
  • two magnetic field generating devices are shown, namely a first magnetic field generating device 3 and a second magnetic field generating device 3'.
  • This example does not limit the positions of the two magnetic field generating devices, and reference may be made to the setting methods of the foregoing embodiments.
  • the first magnetic field generating device 3 and the second magnetic field generating device 3' respectively generate calibration magnetic fields, the distributions of which are shown in the magnetic field lines in Fig. 5 .
  • the calibration magnetic field distributions of the first magnetic field generating device 3 and the second magnetic field generating device 3' can be obtained by calculation.
  • the magnetic field formed by the superposition of the calibration magnetic fields generated by the first magnetic field generating device 3 and the second magnetic field generating device 3 ′ can be decomposed into magnetic fields along the longitudinal direction of the first magnetic field generating device 3
  • the component L 1 and the magnetic field component H 1 in the transverse direction in the same way, at the detector 11 ′ of the second magnetometer 1 ′, the calibration magnetic fields generated by the first magnetic field generating device 3 and the second magnetic field generating device 3 ′ are superimposed and formed by
  • the magnetic field can be decomposed into a magnetic field component L 2 in the longitudinal direction of the second magnetic field generating device 3 ′ and a magnetic field component H 2 in the transverse direction.
  • the detector of a magnetometer measures the magnetic field component in the longitudinal direction.
  • the present disclosure is not limited thereto, and the magnetometer may also be changed in configuration to measure the magnetic field component or the overall magnetic field vector along the lateral direction.
  • the detectors of the magnetometer measure the magnetic field components along the longitudinal direction, ie corresponding to L 1 and L 2 respectively. Further, run the first magnetic field generating device 3 and the second magnetic field generating device 3' to make the first and second magnetic field generating devices 3 and 3' generate a predetermined magnetic field distribution, and use the magnetometers 1 and 1' to measure the size of the magnetic field, respectively, to obtain the measurement. Values M 1 and M 2 .
  • a method such as averaging or square averaging of multiple gain values is used to increase the calibration accuracy.
  • a method such as averaging or square averaging of multiple gain values is used to increase the calibration accuracy.
  • the calibration method may further include calibrating the calibration magnetic field generated by the magnetic field generating device by the calibration device.
  • the calibration method may further include judging whether the gain value deviation of at least one magnetometer in the plurality of magnetometers for different magnetic field generating devices is greater than a threshold value, and when the detection gain value of the at least one magnetometer is greater than the threshold value, Replace the at least one magnetometer or check the magnetic field generating means.
  • the magnetic field generating means are checked or at least one magnetic field generating means is replaced.
  • the threshold value can be preset, for example, the threshold value is set within a range of ⁇ 1%. If the gain value calculated by all or most of the magnetometers for a certain magnetic field generating device deviates from the gain value calculated by other magnetic field generating devices by more than the threshold value, it means that the magnetic field generating device may be faulty or the position has moved; if a magnetometer The gain deviation of the detection gain value for different magnetic field signal sources is greater than the threshold value, indicating that the magnetometer may be faulty or its position has moved. At this time, the magnetometer needs to be replaced or the position of the magnetometer needs to be readjusted.
  • the threshold value may be between 0.1-5%, which is set according to different characteristics of the detector and the supporting device and application scenarios. Those skilled in the art can understand that the threshold value may be 0.1-5%, or -5% to -0.1%. That is to say, the threshold value represents the maximum value of the offset, so it can be positive or negative.
  • FIG. 8 shows a flowchart of a calibration method for a magnetometer according to yet another embodiment of the present invention.
  • This embodiment includes a plurality of magnetic field generating devices, and includes the judgment and inspection steps as described above.
  • the first judgment step is performed to judge whether the deviation of the detection gain value of at least a part of the magnetometers for the frequency of the same calibration magnetic field distribution and the frequencies of other calibration magnetic field distributions is greater than a threshold.
  • a threshold For example, at least a portion of the magnetometers are at least 80% of the number of magnetometers, or all of the magnetometers.
  • a first checking operation is performed, such as calibrating or replacing the magnetic field generating device producing the calibration magnetic field distribution.
  • the first judgment step is performed again until the detection gain value deviation of the frequency of the calibration magnetic field distribution of most magnetometers is less than or equal to the threshold value.
  • the second judgment step can be entered to judge whether the deviation of the detection gain values of the magnetometer for different magnetic field generating devices is greater than the threshold.
  • the thresholds in the above two judgment steps are in the range of 0.1-5%.
  • the threshold value is 0.1%, 0.5%, 1%, 2% or 5%, and when the deviation in the above two judgment steps is greater than the threshold value, an inspection operation is performed.
  • the normal operation of the magnetic field generating device and the detection gain value of the magnetometer can be kept accurate, and the reliability of the system and the accuracy of the measurement results can be improved.
  • determining the spatial position and orientation of the magnetometer includes determining the spatial position and orientation of the magnetometer by the installation position and orientation of the magnetometer on the magnetometer bracket or by photographing positioning marks provided on the magnetometer by a photogrammetry system.
  • a method for continuously calibrating a magnetometer is also provided, and the method is especially suitable for the case where the magnetometer support is flexible, for example, a flexible helmet, but the present invention is not limited to this, also Example that can be applied to rigid supports. Because sometimes the person wearing the helmet cannot avoid head movement, the orientation and position of the magnetometer will change to a certain extent. In this case, using the magnetometer calibration system according to the present disclosure, it is possible to measure the Perform magnetometer calibrations simultaneously or at intervals.
  • the frequency of the magnetic field generated by the magnetic field generating device is different from the frequency of the magnetic field measured by the magnetometer, even if calibration is performed while the magnetometer is measuring, it is possible to extract the predetermined frequency from the measurement result of the magnetometer through the difference in frequency. signal as a measured value.
  • the time domain signal measured by the magnetometer is converted into a frequency domain signal through Fourier transform or other algorithms through a time domain-frequency domain converter, etc., and the detector magnetometer phase is calculated through the calibration measurement value corresponding to the calibration magnetic field frequency. the corresponding target measurement.
  • the position and orientation of the magnetometer can be measured in real time (see the applicant's prior application CN201911190087.2, which is incorporated herein by reference in its entirety), and the measured value of the magnetometer by the dynamic measurement system
  • the position and orientation information is input into the computing device, so that the computing device calculates, based on the position and orientation information and the parameters of the magnetic field generating device, the magnitude of the magnetic field vector of the magnetic field generated by the magnetic field generating device at the location where the magnetometer is located, as the magnitude of the magnetic field.
  • the actual value is calibrated and the calibrated measured value is compared with the calculated calibrated actual value to dynamically calibrate the magnetometer, ie dynamically adjust the gain of the magnetometer.
  • FIG. 9 shows a flowchart of a calibration method for a magnetometer according to yet another embodiment of the present invention.
  • the following description will mainly focus on the differences between this embodiment and the previous embodiments, and similar or identical steps and features will be omitted or briefly described.
  • the calibration method includes the following steps:
  • the magnetic field generating devices 33 in the plurality of magnetic field generating devices are fixedly arranged on the magnetometer 1, and at least another part of the magnetic field generating devices 34 in the plurality of magnetic field generating devices are relative to the magnetometer
  • the position of 1 is fixed, the at least a part of the magnetic field generating means 33 generates a calibration magnetic field, and the other part of the magnetic field generating means 34 generates an additional magnetic field which is fixed or varies with known parameters.
  • the present embodiment adopts the magnetic field generating device 33 fixedly arranged on the magnetometer to generate a calibration magnetic field, and the calibration magnetic field is known. Therefore, it is not necessary to determine the spatial position and orientation of the magnetometer, and it is not necessary to calculate the actual value of the magnetic field at which the magnetometer is located based on the spatial position and orientation of the magnetometer and the calibration magnetic field distribution. Orientation and steps to calculate the spatial magnetic field distribution.
  • the magnetometer 1 and the magnetometer support 2 in step S110 may adopt the arrangement of the embodiment shown in FIG. 4 , which will not be repeated here.
  • the magnetic field generating device 33 may adopt the magnetic field generating device of the foregoing embodiment. During the calibration operation, the magnetic field generating device 33 is turned on to generate a calibration magnetic field. Since the magnetic field generating device 33 is fixedly arranged on the magnetometer 1 , the magnetic field generated in the magnetometer 1 can be considered to be known. In step S130, the magnetometer 1 measures the calibration measurement value MA of the calibration magnetic field. The actual value of the magnetic field generated by the given calibration magnetic field is M 0 .
  • step S140 the calibration gain value K is calculated by the calculation device 4 based on the calibration measurement value M A and the actual value M 0 of the magnetic field.
  • the method of calculating the calibration gain value K and the method of measuring the actual magnetic field magnitude signal value based on the calibration gain value K have been described in the foregoing embodiments (the foregoing embodiment is the detection gain value K), and will not be repeated here.
  • each magnetometer 1 may be provided with a magnetic field generating device 33 , and the respective calibration gain value K of each magnetometer 1 may be measured in step S140 and may be recorded in the computing device 4 .
  • the magnetic field generating device 34 may be disposed on the magnetometer stand 2 or the space to be measured.
  • the magnetic field generating devices 34 may have the same configuration as the magnetic field generating device 33 .
  • the number and position of the magnetic field generating devices 34 can be selected according to needs, and the present disclosure is not limited thereto.
  • step S150 the magnetic field measurement value MB of the additional magnetic field at the position where the magnetometer 1 is located is measured by the magnetometer 1 .
  • step S160 during the operation of the magnetometer 1 , the magnetic field operation measurement value M C of the additional magnetic field at the position where the magnetometer 1 is located is measured by the magnetometer 1 .
  • the magnetic field excitation signal (such as the excitation current) of the magnetic field generating device 34 can be set to remain unchanged or to be Therefore, the actual value M 1 of the magnetic field of the additional magnetic field can remain unchanged or vary with the known parameters.
  • the detection gain value K of the magnetometer 1 can be calculated based on the measured value M B of the magnetic field and the measured value M C of the magnetic field '.
  • the calculation formula of the detection gain value K' is as follows:
  • the detection gain value K' of the magnetometer 1 can be calculated by a similar method based on the magnetic field measurement value MB, the parameters of the additional magnetic field, and the magnetic field working measurement value M C , It is not repeated here.
  • the detection gain value K' of the magnetometer 1 is continuously calculated, and it is judged whether the deviation between different detection gain values K' is greater than the threshold value, if the deviation K of the detection gain value of the magnetometer is 'If it is greater than the threshold, check operation.
  • the purpose of the inspection operations involved in the above-described exemplary embodiments is to inspect the causes of deviations, such as abnormal magnetometer detection, abnormal changes in additional magnetic fields, or environmental noise interference.
  • Those skilled in the art can adopt suitable checking operations to rule out the cause of the deviation, which is not limited by the present disclosure.
  • the threshold value is in the range of 0.1-5%.
  • the threshold value can be 0.1%, 0.5%, 1%, 2% or 5%.
  • the calibration method may further include turning off the magnetic field generating device 33 fixed on the magnetometer 1 during the working process of the magnetometer 1.
  • the magnetic field crosstalk can be prevented, the magnetic field detection accuracy of the magnetometer 1 can be improved, or the device 33 can be used for other purposes.
  • Figure 10 shows a schematic diagram of a magnetometer mount according to an embodiment of the present invention.
  • the embodiment of the present disclosure further provides a magnetometer stand 100 , which includes a mounting portion 200 and at least one magnetic field generating device 3 .
  • the mounting portion 200 is used to mount the magnetometer 1 .
  • the position of the magnetic field generating device 3 is fixed relative to the magnetometer 1 for generating a calibration magnetic field.
  • the magnetometer mount 100 is rigid or flexible.
  • the magnetometer mount 100 is a helmet.
  • the magnetometer stand 100 is rigid, that is, once worn on the subject's head, the relative positions of different magnetometers 1 on the magnetometer stand 100 will not easily change.
  • the magnetometer holder 100 may be made of a non-magnetic material, such as a photosensitive toughened resin or a nano-ceramic material.
  • FIG. 11 shows a schematic block diagram of a magnetic detection system according to an embodiment of the present invention.
  • Embodiments of the present invention further provide a magnetic detection system 300 , including: a magnetometer stand 100 , a magnetometer 1 , a measurement system 500 , a magnetic field generating device 3 and a computing device 4 .
  • the magnetometer 1 is mounted on the magnetometer stand 100 and measures the magnitude of the magnetic field vector at the position where the magnetometer 1 is located.
  • the measurement system 500 is configured to measure the spatial position and orientation of the magnetometer 1 in real time.
  • the magnetic field generating device 3 is arranged at a predetermined position and generates a calibration magnetic field distribution.
  • a calibration magnetic field distribution For the setting manner of the magnetic field generating device 3, reference may be made to the descriptions in the foregoing embodiments, which will not be repeated here.
  • the computing device 4 is configured to calculate a calibrated actual value of the magnetic field vector at the location of the magnetometer 1 based on the spatial position and orientation of the magnetometer 1 measured by the measurement system 500 and said calibrated magnetic field distribution. Furthermore, the computing device 4 also receives the calibration measurement value of the magnetic field vector measured by the magnetometer 1 and compares the calibration actual value with the calibration measurement value to calculate the detection gain value of the magnetometer.
  • the magnetic detection system 300 may also include a time domain to frequency domain converter.
  • the converter is configured to convert the time domain signal measured by the magnetometer into a frequency domain signal through a Fourier transform or other algorithm, and calculate the target measurement corresponding to the magnetometer from the calibration measurement value corresponding to the frequency of the calibration magnetic field value.
  • the converter extracts a signal of a predetermined frequency from the measurement result measured by the magnetometer as the measurement value.
  • the frequency of the calibration magnetic field can be selected according to the frequency of the magnetic field distribution generated by the magnetic field generating device 3, eg, equal to the frequency of the magnetic field distribution.
  • signals of other frequencies except the frequency of the calibration magnetic field are used as the measured value of the magnetic field to be measured and output, and the other frequencies can be in the range of 1-80 Hz, for example.
  • the other frequency may be 1-150 Hz or 1-200 Hz.
  • a magnetic detection system including a magnetometer support, a magnetometer, a first magnetic field generating device and a computing device.
  • the first magnetic field generating means is fixedly disposed on the magnetometer and generates a calibration magnetic field
  • the computing means is configured to receive calibration measurements of the calibration magnetic field measured by the magnetometer, and based on the calibration magnetic field and the calibration measurements to calculate the calibration gain value of the magnetometer.
  • the magnetic detection system may further include a second magnetic field generating device.
  • the second magnetic field generating means is fixed in position relative to the magnetometer and is configured to generate an additional magnetic field.
  • the magnetic detection system is particularly suitable for the calibration method shown in FIG. 9 and embodiments thereof.
  • FIG. 12 shows a flowchart of a magnetic detection method according to an embodiment of the present invention.
  • the embodiment of the present invention also provides a magnetic detection method, the method includes the following steps:
  • the target measurement value (step S103) and the calibration measurement value (step S101) are measured at the same time as the measurement value of the magnetometer, and the target measurement value and the calibration measurement value are in different frequency ranges .
  • step S105 is further included, in which step S105 is divided into frequency of the measurement value of the magnetometer, so as to obtain the calibration measurement value and the target measurement value.
  • the magnetic detection method proposed by the present invention can also perform magnetic detection continuously and in real time.
  • the position and orientation of the magnetometer are measured in real time, and the position and orientation information of the magnetometer is input into the computing device, the actual value of the calibration of the magnetic field at the position of the magnetometer is calculated, and the calibration The measured value is compared with the calculated calibration actual value to continuously calculate the detection gain value.
  • the measurement result of the magnetometer is multiplied by the detection gain value to obtain the actual value of the magnetic field to be measured measured in real time.
  • the calibration system and method provided by the present invention can effectively prevent the crosstalk between the detectors, improve the calibration accuracy, and can realize real-time, continuous , multi-detector collaborative calibration, so as to obtain accurate multi-detector magnetic field recording results.

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Abstract

一种用于磁力计（1）的校准系统，包括：磁力计（1），配置为测量待测磁场；磁力计支架（2），磁力计（1）固定安装在磁力计支架（2）上，以使磁力计（1）的空间位置和取向已知；至少一个磁场发生装置（3），相对于磁力计（1）的位置固定，用于在待测空间中产生校准磁场分布；以及计算装置（4），计算装置（4）配置成根据至少一个磁场发生装置（3）在待测空间内产生的校准磁场分布计算在磁力计（1）所处位置处的磁场矢量大小，从磁力计（1）接收测得的磁场矢量大小，以及基于计算获得的磁场矢量大小和测得的磁场矢量大小计算磁力计（1）的探测增益值。一种用于磁力计（1）的校准方法，磁探测系统和方法，以及磁力计支架（2）。

Description

用于磁力计的校准系统和方法
本申请要求于2020年7月30日递交的中国专利申请第202010753611.9号的优先权，在此全文引用上述中国专利申请公开的内容以作为本申请的一部分。
技术领域
本发明涉及一种用于磁力计的校准系统和方法，以及磁探测系统和磁探测方法，本发明还涉及一种磁力计支架。
背景技术
在弱磁探测领域，需要在工作前对磁探测器的参数进行校准或标定。例如，以超导量子干涉器件(superconducting quantum interference device，SQUID)为核心器件的MEG技术中的磁探测器，需要定期(例如，通过放置生成已知磁场强度的模型)进行探测器增益值检测和进行校准。
而新型的基于无自旋交换弛豫效应(SERF)的光泵原子磁力计测量精度达到甚至超过SQUID磁强计可以达到的水平，并且可以在非超低温环境下工作，无需液氦冷却，体积小重量轻，可通过半导体工艺实现低成本的大批量生产。由于基于SERF效应的磁力计探测的磁场强度由通过光电传感器探测的偏振光束强度或偏振角度计算而得，在基于原子磁力计弱磁检测领域中，为了获得准确的检测结果，需要对探测器(磁力计)的检测增益值进行标定和校准。
尤其是对于使用阵列式多探测器磁力计进行信号探测和溯源定位中，探测器增益值的准确标定对于准确的溯源定位至关重要。现有的原子磁力计在每个探测器中靠近气室的部位，在探测器启动过程中使用线圈生成特定强度的磁场，从而进行探测器的增益校准。这一方法在存在一定外界磁场变化的工作环境中，难以进行准确的多探测器同时标定和协同校准。
基于此，本发明提出一种用于磁力计的校准系统和方法，使用一种可同时作用于所有探测器的磁场信号源进行校准的方法，进行多探测器的协同校准并可以其作为参照信号源，并可在记录过程中对探测器的增益值进行连续性校准，从而获得准确的多探测器磁场记录和溯源定位结果。
发明内容
本发明的实施例提供一种用于磁力计的校准系统，包括磁力计，配置为测量待测磁场；磁力计支架，所述磁力计固定安装在所述磁力计支架上，以使所述磁力计的空间位置和取向已知；至少一个磁场发生装置，相对于所述磁力计的位置固定，用于在所述待测空间中产生校准磁场分布；以及计算装置，所述计算装置配置成根据所述至少一个磁场发生装置在所述待测空间内产生的校准磁场分布计算在磁力计所处位置处的磁场矢量大小，从所述磁力计接收所述磁力计测得的磁场矢量大小，以及基于所述计算获得的磁场矢量大小和测得的磁场矢量大小计算所述磁力计的探测增益值。
本发明的实施例提供一种用于磁力计的校准方法，包括提供安装在磁力计支架上的磁力计，所述磁力计配置为测量磁力计所处位置的磁场大小，作为磁力计的测量值；将至少一个磁场发生装置相对于所述磁力计的位置固定，所述至少一个磁场发生装置配置成产生校准磁场分布；确定磁力计的空间位置和取向，并基于磁力计的空间位置和取向与校准磁场分布，计算所述磁力计所处位置的磁场的校准实际值；通过所述磁力计测量其所处位置的磁场的校准测量值；基于所述校准测量值和所述校准实际值计算所述磁力计的探测增益值。
本发明的实施例提供一种用于磁力计的校准方法，包括提供安装在磁力计支架上的磁力计，所述磁力计配置为测量磁力计所处位置的磁场大小，作为磁力计的测量值；提供多个磁场发生装置，所述多个磁场发生装置中的至少一部分磁场发生装置固定设置在所述磁力计上，该至少一部分磁场发生装置配置成产生校准磁场；通过所述磁力计测量校准磁场的校准测量值；基于所述校准磁场和所述校准测量值，计算所述磁力计的探测增益值；通过另一部分位于磁力计支架上的磁场发生装置产生固定或随已知参数规律变化的磁场，通过校准增益的磁力计对该磁场发生装置产生的磁场的测量值及该测量值在记录过程中的变化，对磁力计的增益值进行校准。在该过程中，初始校准完成后可关闭固定在磁力计上的磁场发生装置。
本发明的实施例提供一种磁探测系统，包括磁力计支架；磁力计，所述磁力计安装在磁力计支架上并测量所处位置的磁场矢量的大小，作为磁力计的测量值；磁场发生装置，所述磁场发生装置设置在预定位置并产生校准磁场分布；以及计算装置，所述计算装置被构造成基于所述磁力计的空间位置和取向以及 所述校准磁场分布计算所述磁力计所处位置的磁场矢量的校准实际值，接收所述磁力计测量的磁场矢量的校准测量值，以及将所述校准实际值与所述校准测量值相比较，以计算所述磁力计的探测增益值。
本发明的实施例一种磁探测系统，包括磁力计支架；磁力计，所述磁力计安装在磁力计支架上并测量所处位置的磁场矢量的大小，作为磁力计的测量值；第一磁场发生装置，所述第一磁场发生装置设置在预定位置并产生校准磁场；以及计算装置，所述计算装置被构造成接收所述磁力计测量的校准磁场的校准测量值，并基于所述校准磁场和所述校准测量值，计算所述磁力计的探测增益值。
本发明的实施例提供一种磁探测方法，包括提供磁力计，所述磁力计安装在磁力计支架上并测量其所处位置的磁场矢量的大小，作为磁力计的测量值；使用如上所述的校准方法得到所述磁力计的探测增益值；通过所述磁力计测量待测磁场；以及将所述磁力计的测量结果乘以所述探测增益值，得到待测磁场的实际值。
本发明的实施例提供一种磁力计支架，包括安装部，用于安装磁力计；和至少一个磁场发生装置，相对于所述磁力计的位置固定，用于产生校准磁场。
附图说明
为了更清楚地说明本发明实施例的技术方案，下文中将对本发明实施例的附图进行简单介绍。其中，附图仅仅用于展示本发明的一些实施例，而非将本发明的全部实施例限制于此。
图1示出了根据本发明一实施例的校准系统的示意图；
图2示出了根据本发明的又一实施例的校准系统的示意图；
图3示出了根据本发明的再一实施例的校准系统的示意图；
图4示出了根据本发明的变型实施例的校准系统的示意图；
图5示出了根据本发明一实施例的磁场发生装置产生的校准磁场的空间分布示意图；
图6示出了图1所示实施例的计算装置得到的磁场强度测量值在频域的分布图；
图7示出了根据本发明一实施例的用于磁力计的校准方法的流程图；
图8示出了根据本发明又一实施例的用于磁力计的校准方法的流程图；
图9示出了根据本发明再一实施例的用于磁力计的校准方法的流程图；
图10示出了根据本发明一实施例的磁力计支架的示意图；
图11示出了根据本发明一实施例的磁探测系统的示意框图；
图12示出了根据本发明一实施例的磁探测方法的流程图。
具体实施方式
为了使得本发明的技术方案的目的、技术方案和优点更加清楚，下文中将结合本发明具体实施例的附图，对本发明实施例的技术方案进行清楚、完整地描述。附图中相同的附图标记代表相同的部件。需要说明的是，所描述的实施例是本发明的一部分实施例，而不是全部的实施例。基于所描述的本发明的实施例，本领域普通技术人员在无需创造性劳动的前提下所获得的所有其他实施例，都属于本发明保护的范围。
除非另作定义，此处使用的技术术语或者科学术语应当为本发明所属领域内具有一般技能的人士所理解的通常意义。本发明专利申请说明书以及权利要求书中使用的“第一”、“第二”以及类似的词语并不表示任何顺序、数量或者重要性，而只是用来区分不同的组成部分。同样，“一个”或者“一”等类似词语也不必然表示数量限制。“包括”或者“包含”等类似的词语意指出现该词前面的元件或物件涵盖出现在该词后面列举的元件或者物件和等同，而不排除其他元件或者物件。“连接”或者“相连”等类似的词语并非限定于物理的或者机械的连接，而是可以包括电性的连接，不管是直接的还是间接的。“上”、“下”、“左”、“右”等仅用于表示相对位置关系，当被描述对象的绝对位置改变后，则该相对位置关系也可能相应地改变。
由于基于SERF效应的光泵原子磁力计(以下简称“磁力计”)是利用弱磁场下原子自旋效应进行磁测量，其探测过程与外界磁场的影响相关，探测器的增益值不仅与探测器本身的硬件和控制参数相关，还受到探测器所处位置净磁场的影响。即使在探测器的非灵敏方向，如沿探测光束入射方向上的磁场，也会影响探测器在灵敏方向上的探测增益。这一特性相比于在不同外界磁场下的增益值基本稳定的传统SQUID灵敏探测器，有着很大的不同，用于传统SQUID探测器阵列的校准方法，例如定期(每次开机测试、每次热机维护或者每个设备常规检修周期)放置生成已知磁场强度的模型进行探测器增益值检测和校准，无法适用于光泵原子磁力计。
使用阵列式多探测器磁力计进行信号探测和溯源定位中，探测器的位置，指向和增益值对于准确的溯源定位至关重要。现有的光泵原子磁力计在每个探测器中靠近气室的部位，在探测器启动过程中使用线圈生成特定强度的磁场，从而进行探测器的增益校准。对于单个探测器，这种方式是有效且可行的。对于多个探测器组成的探测器阵列，校准用线圈产生的磁场会在探测器之间造成串扰，当对一个探测器进行校准时，其所产生的磁场会影响到相邻的其他探测器。所以对于原子磁力计多探测器阵列，现有的装置无法同时进行所有探测器的同步校准，只能通过每个探测器依次校准或者离开一定距离的探测器进行间隔式校准的方式进行校准。这不仅大幅延长了校准所需时间，而且当外界磁场存在变化时，无法准确校准所有探测器。在存在一定外界磁场变化的工作环境中，由现有的探测器组成的多探测器系统无法进行持续性或一定间隔的连续性校准，难以进行准确的多探测器同时记录和信号溯源定位。本发明使用一种基于外置磁场信号源进行校准的系统和方法，进行多探测器的协同校准并可以其作为参照信号源，在记录过程中对探测器的增益值进行连续性校准，从而获得准确的多探测器磁场记录结果。
需要说明的是，本公开中提到的术语“光泵原子磁力计”、“原子磁力计”、“磁力计”指的是基于无自旋交换弛豫效应(SERF)的光泵原子磁力计。本公开并不限于此，本领域的技术人员可以根据本公开内容进行修改和变型而得到的适用于其他磁探测器的校准系统和校准方法，也在本公开的保护范围之内。
以下将结合附图描述本公开的实施例。
图1示出了根据本发明一实施例的校准系统的示意图。图2示出了根据本发明的又一实施例的校准系统的示意图。图3示出了根据本发明的再一实施例的校准系统的示意图。图4示出了根据本发明的变型实施例的校准系统的示意图。
本发明的实施例提供一种用于磁力计的校准系统，包括：磁力计，配置为测量待测磁场；磁力计支架，所述磁力计安装在所述磁力计支架上；至少一个磁场发生装置，相对于所述磁力计的位置固定，用于产生校准磁场；以及计算装置，用于获得所述磁力计的测量结果。所述磁力计配置为测量至少一个磁场发生装置产生的校准磁场，并且所述计算装置基于所述磁力计的测量结果计算磁力计的探测增益值。
示例性地，至少一个磁场发生装置可以设置在磁力计支架、待测空间或磁 力计中的至少一个上。在实际使用中可以根据需求进行选择。不论磁场发生装置设置在何处，磁场发生装置与所有磁力计的相对空间位置及朝向是固定且已知的，或者是可以连续进行标定从而是已知的。并且，磁场发生装置所产生的校准磁场是已知的，从而校准磁场在磁力计所在位置处的磁场分布是已知的，基于磁力计的测量结果与磁场分布可以计算出磁力计的探测增益值。
相较于每个磁力计使用自带信号源进行校准，本发明的校准系统的优势在于，校准时不会与现有的磁力计发生串扰，从而不会影响其他探测器的工作。此外，可以快速同时标定，并且甚至可以在磁力计进行记录的同时连续标定和连续校准。
同时，因为可以进行连续校准并且连续标定探测增益值，采用本发明的校准系统可使在不牺牲灵敏度的情况下，将磁力计的检测动态范围扩大到探测器的非线性区域，扩大检测范围。
该校准系统包括磁力计1、磁力计支架2、至少一个磁场发生装置3和计算装置4。磁场发生装置3可以被构造成产生已知或预设的校准磁场分布，该已知或预设的校准磁场分布是指根据磁场发生装置3的输入或其他参数可以计算获得的磁场分布或者可以通过其他方式获得的磁场分布，该磁场分布用于校准磁力计1的探测增益值。通过该磁场分布，可以获得在该磁场分布中的某一特定空间位置和取向的磁场矢量大小。磁力计1配置为测量待测空间中的待测磁场，例如受试者的脑磁信号。此外，磁力计1也可以用于获得与其他部位生物磁场有关的信息，取决于磁力计1所设置的位置。如图1所示，例如，磁力计支架2是头盔形式，其可以相对于待测空间(例如，受试者的头部)固定设置，并且包括具有预定取向的至少一个安装部(未示出)，允许磁力计1分别沿特定方向以第一深度设置于所述安装部。优选的是，所述磁力计支架2包括多个安装部，磁力计1分别安装到每个安装部上，并相对于磁力计支架固定。由此，通过已知每个安装部的信息，例如，在安装部是安装孔的情况下，已知安装孔的轴向的空间方向和磁力计1插入到安装孔内的深度，则可以确定磁力计1的空间位置和取向信息。
因此，磁力计1固定安装在磁力计支架2上，因此一旦完成安装，磁力计1与安装孔之间的相对位置和取向就可以固定并确定。
在一个实施例中，安装部可以包括例如探测电极，通过探测电极，可以探测到该安装孔内已经安装了磁力计以及磁力计的安装深度。在另一实施例中， 安装部可以设置有传感器，以感测磁力计的安装信息，例如，磁力计的安装深度，以及感测磁力计的识别码，并将磁力计的安装信息，例如，磁力计的安装深度、磁力计的识别码以及该磁力计所安装的安装部的特定信息，例如，安装部的空间取向等发送到计算装置，由此，计算装置可以获得磁力计的空间位置和取向信息。
需要说明的是，磁力计1的探测器为矢量探测器，探测的磁场信息为矢量信息，这与传统的脑电探测仅探测电极标量信号不同。因此，需要测量探测器探测到的磁场矢量信息。并且，磁力计1的探测器可以布置为探测沿磁力计1的纵向轴线方向(长度方向)的磁场强度。
本公开所述的“待测空间”包括但不限于：受试者的头部、腹部或其他身体部位，以及可以检测磁场强度的其他物体，本领域技术人员可以根据实际测量应用进行适应性的选择，本公开对此并不作限制。
如图1所示，校准系统包括多个磁场发生装置3，分别设置相对于磁力计1固定的不同空间位置上。
可选地，多个磁场发生装置3可以设置在磁力计支架2、待测空间或磁力计1中的至少一个上。
在图1示出的实施例中，校准系统包括四个磁场发生装置3，分别设置在磁力计支架2的四个不同空间位置上，例如，其中三个磁场发生装置3位于图1所示的磁力计支架2的下端圆周的三等分处，另一个磁场发生装置3位于磁力计支架2的顶部正上位置。本公开并不以此为限，磁场发生装置3还可以设置在磁力计支架2的其他空间位置，只要保证相对于磁力计位置和取向固定即可，磁场发生装置3的数量也可以根据实际需求增加或减少。
计算装置4通过有线或无线通信的方式与磁力计1和磁场发生装置3连接(在图中以虚线表示)。计算装置4可以采用本领域常见的计算设备，包括但不限于：CPU、DSP、计算机、工作站等。
示例性地，磁场发生装置3可以是线圈回路或浸泡于导电溶液中的偶极子。例如，在本实施例中，磁场发生装置3为励磁线圈构成的线圈回路，在通电时可以产生空间磁场，如图5所示，并由此，可以根据线圈回路的电流大小以及线圈回路的尺寸、线圈匝数等参数计算获得该磁场发生装置3在空间的磁场分布，并由此可以计算得出在该空间内的某一特定位置的磁场矢量的大小和方向。可选地，磁场发生装置3也可以是浸泡于导电溶液中的偶极子。
示例性地，该校准系统还可以包括标定装置，用于标定磁场发生装置产生的校准磁场。标定装置可以设置在磁场发生装置3上或附近，以实现连续标定，或者可以单独设置并且在每次需要标定磁场发生装置3时实施对磁场发生装置3的标定。
示例性地，磁场发生装置3产生的校准磁场的频率范围设定为在待测磁场的频率范围之外。例如，磁场发生装置3产生的校准磁场的频率范围大于待测磁场的频率范围，这样可以防止检测结果的串扰。例如，待测磁场(如脑磁信号)的频率范围为1-80Hz。可选地，磁场发生装置3产生的校准磁场分布的频率范围在80Hz到200Hz的范围内。可选地，磁场发生装置3产生的校准磁场的频率范围可以大于80Hz，例如80-100Hz、80-120Hz、100-200Hz或者大于200Hz。此外，磁场发生装置3产生的校准磁场的频率范围也可以小于待测磁场的频率范围，例如小于40Hz。示例性地，多个磁场发生装置3的每个所产生的校准磁场分布的频率不同，因此可以在频域对不同的磁场发生装置3进行区分。
示例性地，校准系统还包括时域-频域转换器(未示出)，该转换器被配置成将所述磁力计测量的时域信号通过傅里叶变换或其他算法转换成频域信号，通过与校准磁场频率相对应的校准测量值计算磁力计相对应的目标测量值。经过转换器转换后的磁力计时域信号被转换成例如图6所示的频域信号，不同频率的信号在频域各自具有峰值。时域-频域转换器可以是独立的转换芯片，或者是内置在计算装置中的算法。
图6示出了图1所示实施例的计算装置得到的磁场强度测量值在频域的分布图。图6的结果是根据计算装置对其中一个磁力计1所计算的磁场强度测量值。
四个磁场发生装置3分别以不同的频率激发，从而每个磁场发生装置3所产生的校准磁场的频率不同，例如173Hz、178Hz、183Hz、188Hz。该四个磁场发生装置3所产生的磁场强度在频域具有四个峰值，其测量值如图6所示，分别为M 1、M 2、M 3和M 4。通过不同校准磁场频率，可以在频域空间对不同的磁场发生装置3进行区别和标记，且互相之间不会发生干扰或串扰，以便于测量和校准操作。图2示出了根据本公开的又一实施例的校准系统的示意图。与图1所示实施例不同之处在于，本实施例采用更大尺寸的磁场发生装置31，这样可以在空间形成分布更均匀的校准磁场，便于进行校准。
图3示出了根据本公开的再一实施例的校准系统的示意图。与前述实施例不同之处在于，本实施例的磁场发生装置32固定设置在多个磁力计的至少一个上，例如三个，如图3所示。
在一些实施例中，磁场发生装置还可以根据校准需求具有其他布置方式。例如，第一磁场发生装置33可以固定设置在每个磁力计1上，并且至少一个第二磁场发生装置34还可以固定设置在磁力计支架2上，例如两个第二磁场发生装置34，如图4所示。
下面将结合附图描述根据本公开实施例的校准方法。
图5示出了根据本发明一实施例的磁场发生装置产生的校准磁场的空间分布示意图。图7示出了根据本发明一实施例的用于磁力计的校准方法的流程图。
如图7所示，该校准方法包括以下步骤：
S10、提供安装在磁力计支架上的磁力计，所述磁力计配置为测量磁力计所处位置的磁场大小，作为磁力计的测量值。
S20、提供至少一个磁场发生装置，所述至少一个磁场发生装置相对于所述磁力计的位置固定，所述至少一个磁场发生装置产生已知或预定的空间磁场分布。
S30、确定磁力计的空间位置和取向，并基于磁力计的空间位置和取向与校准磁场分布，计算所述磁力计所处位置的磁场的校准实际值。
S40、通过所述磁力计测量其所处位置的磁场的校准测量值。
S50、基于所述校准测量值和所述校准实际值计算所述磁力计的探测增益值。
步骤S10中的磁力计1和磁力计支架2可以采用例如图1-3所示实施例的布置方式，在此不再赘述。
在步骤S20中，磁场发生装置3可以采用前述实施例的磁场发生装置。在校准操作过程中，打开磁场发生装置3以产生校准磁场，校准磁场会形成空间磁场分布，如图5所示。在磁场发生装置3为线圈的实施例中，该校准磁场分布的参数可以通过预先标定得到，并且通过麦克斯韦方程组(Maxwell's equations)及基于麦克斯韦方程组的杰斐缅柯方程(Jefimenko's equations)计算仿真可以模拟出校准磁场的空间磁场分布。在实际计算中，通常可使用其在准静态极限(quasi-static limit)近似条件下的毕奥-萨伐尔定律(Biot-Savart Law) 来进行计算：
Figure PCTCN2021109654-appb-000001
其中，μ 0是真空磁导率，I是源电流，L是积分路径，dl是源电流r的微小线元素，
Figure PCTCN2021109654-appb-000002
是电流元指向待求场点的单位向量。这一仿真步骤也可以在计算装置4中实现。基于该空间磁场分布可以计算出空间任意一点位置的磁场矢量大小。
因此，在步骤S30中，只要知道了任一磁力计1在空间中的位置，即可得到该磁力计1所处位置的校准磁场实际值M 0的大小。而确定磁力计1的空间位置可以采用多种方法，将在下文进一步描述。
在步骤S40中，磁力计1测量校准磁场在该磁力计1所处位置的磁场大小，得到校准测量值M A。
在步骤S50中，通过计算装置4基于校准测量值M A和计算得到的校准实际值M 0计算探测增益值。该探测增益值可以用于校准磁力计1的测量值与实际值之差。
示例性地，该探测增益值可以包括磁力计的探测增益值K。探测增益值K通过将校准磁场实际值M 0与校准测量值M A相除得到，即：
Figure PCTCN2021109654-appb-000003
基于探测增益值K，可以标定该磁力计1。例如，在磁力计1实际工作时，将磁力计1检测的磁场大小信号，即目标测量值乘以探测增益值K，即可得到实际的磁场大小信号值。实际应用中也可能探测器在不同频率上的增益响应为非线性关系，可通过预先标定的探测增益值对不同频率的增益值进行计算。
以图5为例描述本公开的标定方法，图5示出的实施例仅为示例性的，本领域技术人员可以在图5的原理基础上进行变型和修改，仍在本公开的保护范围内。
例如，图5示出了两个磁力计，分别为第一磁力计1和第二磁力计1’。第一磁力计1包括容纳在其中的探测器11，第二磁力计1’内包括容纳在其中的探测器11’，探测器11和探测器11’为磁力计实际探测磁场大小的部件，因此可以以探测器11和探测器11’的位置来作为用于标定的磁力计的位置，并且预 设磁场分布也可以以探测器11和探测器11’的位置为准来计算。
本示例中，示出了两个磁场发生装置，分别为第一磁场发生装置3和第二磁场发生装置3’。本示例对这两个磁场发生装置的位置不做限制，可以参照前述实施例的设置方式。第一磁场发生装置3和第二磁场发生装置3’分别产生校准磁场，其分布如图5的磁力线所示。
计算可得到第一磁场发生装置3和第二磁场发生装置3’的校准磁场分布。例如，在第一磁力计1的探测器11处，第一磁场发生装置3和第二磁场发生装置3’产生的校准磁场叠加形成的磁场可以分解为沿第一磁场发生装置3纵向方向的磁场分量L 1和横向方向的磁场分量H 1，同理，在第二磁力计1’的探测器11’处，第一磁场发生装置3和第二磁场发生装置3’产生的校准磁场叠加形成的磁场可以分解为沿第二磁场发生装置3’纵向方向的磁场分量L 2和横向方向的磁场分量H 2。
通常，磁力计的探测器测量沿纵向方向的磁场分量。本公开不限于此，磁力计也可以改变构造以测量沿横向方向的磁场分量或整体磁场矢量。
在本示例中，磁力计的探测器测量沿纵向方向的磁场分量，即分别对应于L 1和L 2。进一步地，运行第一磁场发生装置3和第二磁场发生装置3’使第一和第二磁场发生装置3和3’产生预定磁场分布，利用磁力计1和1’分别测量磁场大小，得到测量值M 1和M 2。将以上结果带入前述公式，即可分别得到磁力计1和磁力计1’的探测增益值，即探测增益值K 1和K 2，如下：
Figure PCTCN2021109654-appb-000004
Figure PCTCN2021109654-appb-000005
在来自不同磁场发生装置的校准信号计算的增益值偏差小于一定范围ΔK时，多个增益值取平均或平方平均等方法以增加标定精度。当一个或多个增益值与其他有显著偏离时，提示可能磁场发生装置、探测器或探测器支架发生异常，进行检查和修复。
示例性地，该校准方法还可以包括通过标定装置标定磁场发生装置产生的校准磁场。
示例性地，该校准方法还可以包括判断多个磁力计中的至少一个磁力计对不同磁场发生装置的增益值偏差是否大于阈值，并且在所述至少一个磁力计的探测增益值大于阈值时，替换所述至少一个磁力计或检查磁场发生装置。
例如，当大部分磁力计的某个增益偏差超过阈值时，检查磁场发生装置或替换至少一个磁场发生装置。阈值可以预先设定，例如阈值设定为±1％的范围内。如果所有或大部分磁力计对某一磁场发生装置计算的增益值与其他磁场发生装置计算的增益值偏差大于阈值，则说明该磁场发生装置可能发生故障或者位置发生了移动；如果某一磁力计的探测增益值对不同磁场信号源的增益偏差大于阈值，则说明可能该磁力计发生故障或其位置发生了移动，此时需要替换该磁力计或者重新调整该磁力计的位置。
示例性地，阈值可以介于0.1-5％之间，根据探测器及支撑装置和应用场景的不同特性而设定。本领域技术人员可以理解的是，阈值的取值可以是0.1-5％，也可以是-5％至-0.1％。也就是说，阈值表征的是偏移程度的最大值，因此可以是正值也可以是负值。
图8示出了根据本发明又一实施例的用于磁力计的校准方法的流程图。与图7所示的实施例不同之处在于，该实施例包括多个磁场发生装置，并且包括如上所述的判断和检查步骤。
在步骤S30之后，首先进行第一判断步骤，判断多个磁力计中的至少一部分磁力计对同一校准磁场分布的频率的探测增益值与对其他校准磁场分布的频率的偏差是否大于阈值。例如，至少一部分磁力计为至少80％数量的磁力计，或者所有磁力计。
如果大于阈值，则进行第一检查操作，例如标定产生该校准磁场分布的磁场发生装置或替换该磁场发生装置。在进行第一检查操作之后，重新进行第一判断步骤，直至大部分磁力计对该校准磁场分布的频率的探测增益值偏差小于等于阈值。
如果通过第一判断步骤，即上述偏差小于等于阈值，则可以进入第二判断步骤，判断磁力计对不同的磁场发生装置的探测增益值的偏差是否大于阈值。
如果大于阈值，则进行第二检查操作，例如替换该磁力计，并重新进行第一判断步骤，直至其对不同的磁场发生装置的探测增益值的偏差小于等于阈值。
示例性地，上述两个判断步骤中的阈值取值在0.1-5％的范围内。例如，阈值取值为0.1％、0.5％、1％、2％或5％，当上述两个判断步骤中的偏差大于阈值时，进行检查操作。
在本实施例中，通过引入两个判断和检查步骤，可以确保磁场发生装置的 正常工作和磁力计的探测增益值保持准确，提高系统的可靠度和测量结果的准确性。
示例性地，确定磁力计的空间位置和取向包括通过磁力计在磁力计支架的安装位置和取向或通过摄影测量系统拍摄设置在磁力计上的定位标记从而确定磁力计的空间位置和取向。
在未示出的另一实施例中，还提供了一种连续校准磁力计的方法，该方法尤其适用于磁力计支架为柔性的，例如，柔性头盔的情况，但本发明不限于此，也可以应用于刚性支架的示例。由于有时候佩戴该头盔的人员无法避免头部移动，使得磁力计的取向和位置会发生一定的变化，在这种情况下，采用根据本公开的磁力计校准系统，可以在磁力计进行测量的同时或间隔开地进行磁力计校准。由于磁场发生装置产生的磁场的频率不同于磁力计测量的磁场的频率，因此，即使在磁力计进行测量的同时进行校准，也可以通过频率的不同，在磁力计的测量结果中提取预定频率的信号作为测量值。例如，通过时域-频域转换器等将磁力计测量的时域信号通过傅里叶变换或其他算法转换成频域信号，通过与校准磁场频率相对应的校准测量值计算探测器磁力计相对应的目标测量值。
同时，利用动态测量系统，可以实时测量磁力计的位置和取向(参见本申请人的在先申请CN201911190087.2，其通过引用整体并入本文)，并且将该动态测量系统测得的磁力计的位置和取向信息输入到计算装置中，从而计算装置基于该位置和取向信息和磁场发生装置的参数，计算该磁场发生装置产生的磁场分布在该磁力计所处位置的磁场矢量大小，作为磁场的校准实际值，并且将校准测量值与计算得到的校准实际值相比较，从而动态校准磁力计，即，动态调整磁力计的增益。通过动态调整磁力计的增益值，并将调整后的增益值应用于磁力计的目标测量值，由此，实现更准确的测量。
图9示出了根据本发明再一实施例的用于磁力计的校准方法的流程图。为了便于描述，以下将主要针对本实施例与前述实施例的区别进行描述，相似或相同的步骤和特征将省略或简略描述。
如图9所示，该校准方法包括以下步骤：
S110、提供安装在磁力计支架2上的磁力计1，磁力计1配置为测量磁力计1所处位置的磁场大小，作为磁力计1的测量值。
S120、提供多个磁场发生装置，该多个磁场发生装置中的至少一部分磁场 发生装置33固定设置在磁力计1上，该多个磁场发生装置中的至少另一部分磁场发生装置34相对于磁力计1的位置固定，该至少一部分磁场发生装置33产生校准磁场，该另一部分磁场发生装置34产生固定或随已知参数变化的附加磁场。
S130、通过磁力计1测量校准磁场的校准测量值M A。
S140、基于校准磁场和校准测量值，计算磁力计1的校准增益值K。
S150、通过磁力计1测量磁力计1所处位置的附加磁场的磁场测量值M B。
S160、在磁力计1工作过程中，通过磁力计1测量磁力计1所处位置的附加磁场的磁场工作测量值M C，基于磁场测量值M B、附加磁场的参数以及磁场工作测量值M C，计算磁力计1的探测增益值K’。在该过程中，固定设置在磁力计上的磁场发生装置33可关闭。
与前述实施例不同，本实施例采用固定设置在磁力计上的磁场发生装置33产生校准磁场，该校准磁场是已知的。因此，不需要确定磁力计的空间位置和取向，并且不需要基于磁力计的空间位置和取向与校准磁场分布来计算磁力计所处位置的磁场的校准实际值，省略了确定磁力计空间位置和取向以及计算空间磁场分布的步骤。
步骤S110中的磁力计1和磁力计支架2可以采用例如图4所示实施例的布置方式，在此不再赘述。
在步骤S120中，磁场发生装置33可以采用前述实施例的磁场发生装置。在校准操作过程中，打开磁场发生装置33以产生校准磁场，由于磁场发生装置33固定设置在磁力计1上，其在磁力计1产生的磁场可以认为是已知的。在步骤S130中，磁力计1测量校准磁场的校准测量值M A。给定该校准磁场产生的磁场实际值为M 0。
在步骤S140中，通过计算装置4基于校准测量值M A和磁场实际值M 0计算校准增益值K。计算校准增益值K的方法以及基于校准增益值K测量实际磁场大小信号值的方法已在前述实施例中描述(前述实施例为探测增益值K)，在此不再赘述。
此外，每个磁力计1均可以设置有磁场发生装置33，步骤S140可以测量每个磁力计1的各自的校准增益值K，并且可以记录在计算装置4中。
可选地，磁场发生装置34可以设置在磁力计支架2或待测空间上。例如，如图4所示，两个磁场发生装置34固定设置在磁力计支架2的不同位置上， 并且磁场发生装置34可以与磁场发生装置33具有相同的配置。可选地，磁场发生装置34的数量和位置可以根据需要进行选择，本公开并不以此为限。
在步骤S150中，通过磁力计1测量磁力计1所处位置的附加磁场的磁场测量值M B。并且在步骤S160中，在磁力计1工作过程中，通过磁力计1测量磁力计1所处位置的附加磁场的磁场工作测量值M C。
由于校准增益值K已经在步骤S140中得到，基于校准增益值K和测量值M B可以计算磁力计1所处位置的附加磁场的磁场实际值M 1，即M 1＝K×M B。在磁力计1工作过程中，由于磁场发生装置34的位置相对于磁力计1是固定的，且可以在步骤S150中设置磁场发生装置34的磁场激励信号(例如激励电流)保持不变或以已知参数变化，因此附加磁场的磁场实际值M 1可以保持不变或随已知参数变化。
在附加磁场的磁场实际值M 1保持不变的情况下，即M 1＝K’×M C，基于磁场测量值M B以及磁场工作测量值M C，可以计算磁力计1的探测增益值K’。探测增益值K’的计算公式如下：
K’＝K×M B/M C
基于以上原理，通过测量附加磁场的磁场工作测量值M C，可以实时监测探测增益值K’是否发生变化。同样地，在附加磁场随已知参数变化的情况下，基于磁场测量值M B、附加磁场的参数以及磁场工作测量值M C，采用类似的方法可以计算磁力计1的探测增益值K’，在此不再赘述。
示例性地，判断磁力计的校准增益值K与探测增益值K’的偏差是否大于阈值。如果该磁力计的校准增益值K与探测增益值K’的偏差大于阈值，则进行检查操作。
示例性地，在磁力计工作过程中，连续计算磁力计1的探测增益值K’，并判断不同的探测增益值K’之间的偏差是否大于阈值，如果磁力计的探测增益值的偏差K’大于阈值，则进行检查操作。
上述示例性实施例涉及的检查操作目的在于检查偏差造成的原因，例如磁力计检测异常、附加磁场异常变化或环境噪声干扰等。本领域技术人员可以采用合适的检查操作以排除偏差的原因，本公开并不对此作出限制。
可选地，阈值取值在0.1-5％的范围内。例如，阈值取值为0.1％、0.5％、1％、2％或5％。
示例性地，该校准方法还可以包括在磁力计1工作过程中关闭固定设置在 磁力计1上的磁场发生装置33。通过上述步骤，可以防止产生磁场串扰，提高磁力计1的磁场检测精度，或将装置33用于其他用途。
图10示出了根据本发明一实施例的磁力计支架的示意图。本公开实施例还提供一种磁力计支架100，包括安装部200和至少一个磁场发生装置3。安装部200用于安装磁力计1。磁场发生装置3相对于磁力计1的位置固定，用于产生校准磁场。
可选地，磁力计支架100为刚性或柔性。
可选地，磁力计支架100为头盔。
在本实施例中，磁力计支架100为刚性的，即一旦佩戴在受试者头部，磁力计支架100上的不同磁力计1之间的相对位置不会轻易发生改变。磁力计支架100可以由非磁性材料制成，例如光敏增韧树脂或纳米陶瓷材料。
图11示出了根据本发明一实施例的磁探测系统的示意框图。本发明的实施例还提供一种磁探测系统300，包括：磁力计支架100、磁力计1、测量系统500、磁场发生装置3和计算装置4。参考前述实施例的描述，磁力计1安装在磁力计支架100上并测量磁力计1所处位置的磁场矢量的大小。测量系统500被构造成实时测量磁力计1的空间位置和取向。
磁场发生装置3设置在预定位置并产生校准磁场分布。磁场发生装置3的设置方式可以参照前述实施例中的描述，在此不再赘述。
计算装置4被构造成基于测量系统500测量的磁力计1的空间位置和取向以及所述校准磁场分布计算磁力计1所处位置的磁场矢量的校准实际值。并且，计算装置4还接收磁力计1测量的磁场矢量的校准测量值，并将校准实际值与校准测量值相比较，以计算磁力计的探测增益值。
可选地，磁探测系统300还可以包括时域-频域转换器。转换器被配置成将所述磁力计测量的时域信号通过傅里叶变换或其他算法转换成频域信号，通过与所述校准磁场频率相对应的校准测量值计算磁力计相对应的目标测量值。转换器在磁力计测量的测量结果中提取预定频率的信号作为所述测量值。
校准磁场频率可以根据磁场发生装置3产生的磁场分布的频率进行选择，例如等于该磁场分布的频率。并且将除校准磁场频率以外的其他频率的信号作为待测磁场的测量值并输出，该其他频率可以在例如1-80Hz的范围内。在待测目标为人脑的脑磁的情况下，该其他频率可以为1-150Hz或1-200Hz。
在未示出的另一实施例中，还提供了一种磁探测系统，包括磁力计支架、 磁力计、第一磁场发生装置和计算装置。与前述实施例不同的是，第一磁场发生装置固定设置在磁力计上并产生校准磁场，而计算装置被构造成接收磁力计测量的校准磁场的校准测量值，并基于校准磁场和校准测量值来计算磁力计的校准增益值。
可选地，该磁探测系统还可以包括第二磁场发生装置。第二磁场发生装置相对于磁力计的位置固定，并且配置成产生附加磁场。该磁探测系统特别地适用于图9所示校准方法及其实施例。
图12示出了根据本发明一实施例的磁探测方法的流程图。本发明的实施例还提供一种磁探测方法，该方法包括以下步骤：
S101、提供磁力计，所述磁力计安装在磁力计支架上并测量其所处位置的磁场矢量的大小，作为磁力计的测量值。
S102、使用如前所述的校准方法得到所述磁力计的探测增益值。
S103、通过所述磁力计测量待测磁场得到目标测量值。
S104、将所述磁力计的目标测量值乘以所述探测增益值，得到待测磁场的实际值。
其中，所述目标测量值(步骤S103)和所述校准测量值(步骤S101)同时测量，共同作为磁力计的测量值，并且所述目标测量值和所述校准测量值处于不同的频率范围内。
优选的是，还包括步骤S105，在该步骤S105中，将所述磁力计的测量值分频，从而获得校准测量值和目标测量值。
可选地，本发明所提出的磁探测方法也可以连续、实时地进行磁探测。例如，在磁力计工作过程中实时测量磁力计的位置和取向，并将磁力计的位置和取向信息输入到计算装置中，计算所述磁力计所处位置的磁场的校准实际值，并且将校准测量值与计算得到的校准实际值相比较，从而连续计算探测增益值。并且，将所述磁力计的测量结果乘以所述探测增益值，得到实时测量的待测磁场的实际值。
相比于传统的SQUID探测器阵列和在每个探测器设置校准线圈的校准方法，本发明提供的校准系统和方法具备可以有效防止探测器之间的串扰，提高校准精度，同时可以实时、连续、多探测器协同进行校准，从而获得准确的多探测器磁场记录结果。
上文中参照优选的实施例详细描述了本发明所提出的用于磁力计空间定 位的系统和方法的示范性实施方式，然而本领域技术人员可理解的是，在不背离本发明理念的前提下，可以对上述具体实施例做出多种变型和改型。另外，也可以对本发明各个方面提出的各种技术特征、结构进行多种组合，而不超出本发明的保护范围，本发明的保护范围由所附的权利要求确定。

Claims (47)

  1. 一种用于磁力计的校准系统，包括：
    磁力计，配置为测量待测空间中的待测磁场；
    磁力计支架，所述磁力计固定安装在所述磁力计支架上，以使所述磁力计的空间位置和取向已知；
    至少一个磁场发生装置，相对于所述磁力计的位置固定，用于在所述待测空间中产生校准磁场分布；以及
    计算装置，所述计算装置配置成根据所述至少一个磁场发生装置在所述待测空间内产生的校准磁场分布计算在磁力计所处位置处的磁场矢量大小，从所述磁力计接收所述磁力计测得的磁场矢量大小，以及基于所述计算获得的磁场矢量大小和测得的磁场矢量大小计算所述磁力计的探测增益值。
  2. 根据权利要求1所述的校准系统，其中，所述至少一个磁场发生装置设置在磁力计支架、待测空间或磁力计中的至少一个上。
  3. 根据权利要求1所述的校准系统，包括：多个磁场发生装置，分别设置相对于磁力计固定的不同空间位置上。
  4. 根据权利要求3所述的校准系统，其中，所述多个磁场发生装置设置在磁力计支架、待测空间或磁力计中的至少一个上。
  5. 根据权利要求1-4中任一项所述的校准系统，其中，所述磁场发生装置为线圈回路或浸泡于导电溶液中的偶极子。
  6. 根据权利要求1-5中任一项所述的校准系统，还包括：标定装置，用于标定磁场发生装置产生的校准磁场分布。
  7. 根据权利要求1-6中任一项所述的校准系统，其中，所述磁场发生装置产生的校准磁场分布的频率在待测磁场的频率范围之外。
  8. 根据权利要求1-7中任一项所述的校准系统，其中，所述多个磁场发生装置的每个所产生的校准磁场分布的频率不同。
  9. 根据权利要求7或8所述的校准系统，其中，所述磁场发生装置产生的校准磁场分布的频率在80Hz到200Hz的范围内。
  10. 根据权利要求7至9中任一项所述的校准系统，其中，所述校准系统包括多个磁力计，所述计算装置被配置为确定所述多个磁力计中的至少一部分磁力计对同一校准磁场分布的频率的探测增益值与对其他校准磁场分布的频 率的偏差均大于阈值，并且在所述偏差均大于阈值时，指示对产生该校准磁场分布的磁场发生装置进行标定或替换该磁场发生装置。
  11. 根据权利要求10所述的校准系统，其中，所述至少一部分磁力计为至少80％数量的磁力计。
  12. 根据权利要求10或11所述的校准系统，其中，所述计算装置被配置为确定磁力计对不同的磁场发生装置的探测增益值的偏差是否大于阈值，如果该磁力计的探测增益值的偏差大于阈值，则指示该磁力计需要更换。
  13. 根据权利要求10-12中任一项所述的校准系统，其中，所述阈值取值在0.1-5％的范围内。
  14. 根据权利要求7-13中任一项所述的校准系统，还包括时域-频域转换器，所述转换器被配置成将所述磁力计测量的时域信号通过傅里叶变换或其他算法转换成频域信号，通过与所述校准磁场频率相对应的校准测量值计算磁力计相对应的目标测量值。
  15. 根据权利要求14所述的校准系统，其中，所述计算装置被配置成根据所述校准测量值计算所述磁力计的探测增益值，并将所计算的探测增益值施加到所述目标测量值以获得待测磁场的测量结果。
  16. 一种用于磁力计的校准方法，包括：
    提供安装在磁力计支架上的磁力计，所述磁力计配置为测量磁力计所处位置的磁场大小，作为磁力计的测量值；
    提供至少一个磁场发生装置，所述至少一个磁场发生装置相对于所述磁力计的位置固定，所述至少一个磁场发生装置配置成产生校准磁场分布；
    确定磁力计的空间位置和取向，并基于磁力计的空间位置和取向与校准磁场分布，计算所述磁力计所处位置的磁场的校准实际值；
    通过所述磁力计测量其所处位置的磁场的校准测量值；
    基于所述校准测量值和所述校准实际值计算所述磁力计的探测增益值。
  17. 根据权利要求16所述的校准方法，其中，包括多个磁力计，所述方法还包括：
    判断多个磁力计中的至少一部分对同一校准磁场分布的频率的探测增益值与对其他频率的校准磁场分布的偏差是否大于阈值，并且在所述部分磁力计的偏差均大于阈值时，对产生该校准磁场分布的磁场发生装置进行标定或替换该磁场发生装置。
  18. 根据权利要求17所述的校准方法，其中，所述至少一部分磁力计为至少80％数量的磁力计。
  19. 根据权利要求16至18中任一项所述的校准方法，还包括：
    判断磁力计对不同的磁场发生装置的探测增益值的偏差是否大于阈值，如果该磁力计的探测增益值的偏差大于阈值，则更换该磁力计。
  20. 根据权利要求17-18中任一项所述的校准方法，其中，所述阈值取值在0.1-5％的范围内。
  21. 根据权利要求16所述的校准方法，其中，确定磁力计的空间位置和取向包括通过磁力计在磁力计支架的安装位置和取向或通过摄影测量系统拍摄设置在磁力计上的定位标记从而确定磁力计的空间位置和取向。
  22. 根据权利要求16-21中任一项所述的校准方法，还包括：在磁力计工作过程中连续计算探测增益值。
  23. 根据权利要求22所述的校准方法，其中，在磁力计工作过程中连续计算探测增益值包括：在磁力计工作过程中实时测量磁力计的位置和取向，并将磁力计的位置和取向信息输入到计算装置中，计算所述磁力计所处位置的磁场校准实际值，并且将校准测量值与计算得到的校准实际值相比较，从而连续计算探测增益值。
  24. 根据权利要求22所述的校准方法，其中，在磁力计工作过程中连续计算探测增益值还包括：通过时域-频域转换器在所述磁力计测量的测量结果中提取预定频率的信号作为所述测量值。
  25. 一种用于磁力计的校准方法，包括：
    提供安装在磁力计支架上的磁力计，所述磁力计配置为测量磁力计所处位置的磁场大小，作为磁力计的测量值；
    提供多个磁场发生装置，所述多个磁场发生装置中的至少一部分磁场发生装置固定设置在所述磁力计上，所述多个磁场发生装置中的至少另一部分磁场发生装置相对于所述磁力计的位置固定，该至少一部分磁场发生装置产生校准磁场，该另一部分磁场发生装置产生固定或随已知参数变化的附加磁场；
    通过所述磁力计测量校准磁场的校准测量值；
    基于所述校准磁场和所述校准测量值，计算所述磁力计的校准增益值；
    通过所述磁力计测量所述磁力计所处位置的附加磁场的磁场测量值；
    在磁力计工作过程中，通过所述磁力计测量所述磁力计所处位置的附加磁 场的磁场工作测量值，基于所述磁场测量值、所述附加磁场的参数以及磁场工作测量值，计算所述磁力计的探测增益值。
  26. 根据权利要求25所述的校准方法，还包括：
    在磁力计工作过程中，关闭固定设置在所述磁力计上的该至少一部分磁场发生装置。
  27. 根据权利要求26所述的校准方法，还包括：
    判断磁力计的校准增益值与探测增益值的偏差是否大于阈值，如果该磁力计的校准增益值与探测增益值的偏差大于阈值，则进行检查操作。
  28. 根据权利要求26或27所述的校准方法，还包括：
    在磁力计工作过程中，连续计算磁力计的探测增益值，并判断探测增益值的偏差是否大于阈值，如果磁力计的探测增益值的偏差大于阈值，则进行检查操作。
  29. 根据权利要求27或28所述的校准方法，其中，所述阈值取值在0.1-5％的范围内。
  30. 根据权利要求25-29中任一项所述的校准方法，其中，所述多个磁场发生装置中的至少另一部分磁场发生装置设置在磁力计支架或待测空间上。
  31. 一种磁探测系统，包括：
    磁力计支架；
    磁力计，所述磁力计安装在磁力计支架上并测量所处位置的磁场矢量的大小，作为磁力计的测量值；
    磁场发生装置，所述磁场发生装置设置在预定位置并产生校准磁场分布；以及
    计算装置，所述计算装置被构造成基于所述磁力计的空间位置和取向以及所述校准磁场分布计算所述磁力计所处位置的磁场矢量的校准实际值，接收所述磁力计测量的磁场矢量的校准测量值，以及将所述校准实际值与所述校准测量值相比较，以计算所述磁力计的探测增益值。
  32. 根据权利要求31所述的磁探测系统，其中，所述磁力计支架是头盔，所述头盔是刚性的或柔性的。
  33. 根据权利要求31或32所述的磁探测系统，还包括测量系统，所述测量系统被构造成实时测量所述磁力计的空间位置和取向，并且其中所述计算装置被构造成基于所述测量系统测量的磁力计的空间位置和取向以及所述校准 磁场分布计算所述磁力计所处位置的磁场矢量计算校准实际值。
  34. 根据权利要求31-33中任一项所述的磁探测系统，还包括时域-频域转换器，所述转换器在所述磁力计测量的测量结果中提取预定频率的信号作为所述测量值。
  35. 根据权利要求31-34中任一项所述的磁探测系统，其中，所述磁力计还被构造成探测待探测目标的磁场以获得目标测量值，并且所述计算装置被构造成将所述探测增益值施加到所述目标测量值以得到所述待测磁场的实际值。
  36. 根据权利要求35所述的磁探测系统，其中，所述校准测量值与所述目标测量值的频率不同。
  37. 一种磁探测系统，包括：
    磁力计支架；
    磁力计，所述磁力计安装在磁力计支架上并测量所处位置的磁场矢量的大小，作为磁力计的测量值；
    第一磁场发生装置，所述第一磁场发生装置固定设置在磁力计上并产生校准磁场；以及
    计算装置，所述计算装置被构造成接收所述磁力计测量的校准磁场的校准测量值，并基于所述校准磁场和所述校准测量值，计算所述磁力计的探测增益值。
  38. 根据权利要求37所述的磁探测系统，还包括：
    第二磁场发生装置，所述第二磁场发生装置相对于所述磁力计的位置固定，并且配置成产生附加磁场。
  39. 根据权利要求37或38所述的磁探测系统，其中，所述磁力计支架是头盔，所述头盔是刚性的或柔性的。
  40. 根据权利要求37-39中任一项所述的磁探测系统，还包括：时域-频域转换器，所述转换器在所述磁力计测量的测量结果中提取预定频率的信号作为所述测量值。
  41. 根据权利要求37-40中任一项所述的磁探测系统，其中，所述磁力计还被构造成探测待探测目标的磁场以获得目标测量值，并且所述计算装置被构造成将所述探测增益值施加到所述目标测量值以得到所述待测磁场的实际值。
  42. 根据权利要求41所述的磁探测系统，其中，所述校准测量值与所述目标测量值的频率不同。
  43. 一种磁探测方法，包括：
    提供磁力计，所述磁力计安装在磁力计支架上并测量其所处位置的磁场矢量的大小，作为磁力计的测量值；
    使用如权利要求16-30中任一项所述的校准方法得到所述磁力计的探测增益值；
    通过所述磁力计测量待测磁场；以及
    将所述磁力计的测量结果乘以所述探测增益值，得到待测磁场的实际值。
  44. 根据权利要求43所述的磁探测方法，还包括：
    在磁力计工作过程中实时测量磁力计的位置和取向，并将磁力计的位置和取向信息输入到计算装置中，计算所述磁力计所处位置的校准实际值，并且将校准测量值与计算得到的校准实际值相比较，从而连续计算探测增益值；以及
    将所述磁力计的目标测量值乘以所述探测增益值，得到实时测量的待测磁场的实际值。
  45. 一种磁力计支架，包括：
    安装部，用于安装磁力计；和
    至少一个磁场发生装置，相对于所述磁力计的位置固定，用于产生校准磁场。
  46. 根据权利要求45所述的磁力计支架，其中，所述磁力计支架为刚性或柔性。
  47. 根据权利要求45或46所述的磁力计支架，其中，所述磁力计支架为头盔。
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