Vector magnetic field probe and vector magnetic field measurement method

Abstract

The present invention discloses a vector magnetic field probe and a vector magnetic field measurement method, which belong to the field of magnetic field measurement and include: a magnetic sensitive detector made of diamond containing nitrogen vacancy centers; a light guide module, the magnetic sensitive detector is fixed to the end of the light guide module, the light guide module is used to transmit an external laser of a preset wavelength to the magnetic sensitive detector, and to derive the fluorescence emitted by the magnetic sensitive detector; a magnetic field generator is used to apply a stable static magnetic field to the magnetic sensitive detector; a control field generator is used to apply a preset electromagnetic field to the magnetic sensitive detector; and a magnetic field amplifier, including three pairs of magnetic amplification units that are centrally symmetrical and whose central axes are perpendicular to each other, and the area enclosed by the plane where the minimum cross-section of each magnetic amplification unit is located is the magnetic amplification area; when working, the magnetic field amplifier is located in the vector magnetic field to be measured, and the magnetic sensitive detector is located in the magnetic amplification area. The present invention can simultaneously measure the magnitude and direction of the magnetic field and has high sensitivity to vector magnetic fields in any direction.

Description

Technical Field

[0001] The present invention belongs to the field of magnetic field measurement, and more specifically, relates to a vector magnetic field probe and a vector magnetic field measurement method. Background Art

[0002] Measuring magnetic fields using nitrogen-vacancy centers in diamond is a common measurement method. Nitrogen-vacancy centers are formed when a nitrogen atom replaces a carbon atom in diamond and then captures a surrounding hole. This junction is structurally stable, particularly sensitive to magnetic fields, and its state can be read optically, making it widely studied in the field of magnetic field measurement. The sensitivity of nitrogen-vacancy center single quantum interferometers in measuring magnetic fields can reach 10 -9 T level, the nitrogen-vacancy center ensemble can reach 10 -13 The T level can even be used to directly measure weak geomagnetic fields.

[0003] However, the high sensitivity currently achieved by sensors based on nitrogen-vacancy centers has been achieved only in laboratory settings. In actual use, due to environmental factors, equipment, noise, and other factors, the sensitivity cannot reach the laboratory specifications. Therefore, if the ambient magnetic field could be amplified by a certain factor before measurement, the sensor's sensitivity and resolution to magnetic fields could be significantly improved, allowing sensors based on diamond nitrogen-vacancy centers to achieve high sensitivity even in practical use.

[0004] The patent application document with application publication number CN103439749A discloses a magnetic focusing amplification guide structure used to amplify weak geomagnetic fields. However, the amplifier can only be used to amplify magnetic fields in a specific direction. For magnetic fields perpendicular to the structure, the amplified field strength may even be reduced, which limits its possibility of being used for vector magnetic field measurement.

[0005] The patent application document with application publication number CN 112180303 A discloses a diamond-based magnetometer probe. The probe adopts a one-dimensional magnetic focusing amplification structure. The characteristics of the magnetic focusing amplification structure determine that the magnetic probe has certain defects when measuring complex vector magnetic fields. In addition, the one-dimensional magnetic focusing amplification structure can only amplify the magnetic field in a specific direction, which will be subject to certain limitations in vector magnetic field measurements.

[0006] In general, the existing magnetic field measurement structure based on nitrogen-vacancy centers can only achieve magnetic field amplification in a specific direction and cannot guarantee high detection sensitivity for vector magnetic fields in any direction, and its use in actual measurement scenarios is limited. Summary of the Invention

[0007] In response to the defects of the existing technology and the need for improvement, the present invention provides a vector magnetic field probe and a vector magnetic field measurement method, the purpose of which is to simultaneously measure the magnitude and direction of the vector magnetic field and ensure high sensitivity to vector magnetic fields in any direction.

[0008] To achieve the above object, according to one aspect of the present invention, a vector magnetic field probe is provided, comprising: a magnetic sensitive detector, a light guide module, a control field generator, a magnetic field generator, and a magnetic field amplifier;

[0009] The magnetic sensitive detector is made of diamond containing nitrogen-vacancy centers and is fixed to the end of the light guide module; the light guide module is used to transmit external laser light of a preset wavelength to the magnetic sensitive detector; the control field generator is used to apply a preset electromagnetic field to the magnetic sensitive detector; the magnetic field generator is used to apply a stable static magnetic field to the magnetic sensitive detector;

[0010] The magnetic field amplifier includes three pairs of magnetic amplification units that are centrally symmetrical and whose central axes are perpendicular to each other. In the cross-section of the magnetic amplification units along the central axis, the closer the cross-section is to the symmetry center, the smaller the cross-section is. The area enclosed by the plane where the minimum cross-section of each magnetic amplification unit is located is the magnetic amplification area.

[0011] During operation, the magnetic field amplifier is located in the vector magnetic field to be measured, and the magnetically sensitive detector is located in the magnetic amplification area; under the combined action of external laser, electromagnetic field and static magnetic field, the magnetically sensitive detector emits fluorescence carrying information on the magnitude and direction of the vector magnetic field; the light guide module is also used to guide the fluorescence emitted by the magnetically sensitive detector.

[0012] The solid-state spins inside the nitrogen-vacancy center are sensitive to magnetic fields, and the fluorescence emitted after being irradiated by a preset laser and manipulated by a microwave control field can reflect the magnetic field information to be measured. The vector magnetic field probe provided by the present invention includes not only a light guide module for transmitting external laser light and a control field generator for applying a control field, but also a magnetic field generator for applying a stable static magnetic field. Under the combined action of the external laser, the control field, and the static magnetic field, the fluorescence signal emitted by the magnetically sensitive detector simultaneously carries information on the magnitude and direction of the vector magnetic field. By analyzing this fluorescence signal, the magnitude and direction of the vector magnetic field can be measured simultaneously.

[0013] The vector magnetic field probe provided by the present invention comprises a magnetic field amplifier comprising three pairs of magnetic amplification units that are centrally symmetrical and whose central axes are perpendicular to each other. Based on this structure, the magnetic field amplifier can amplify the vector magnetic field in any direction by a certain multiple, so that the magnetic sensitive detector made of a diamond sample containing nitrogen-vacancy centers has a high detection sensitivity for vector magnetic fields in any direction.

[0014] Furthermore, the light guide module is an optical fiber.

[0015] The present invention adopts optical fiber as a light guide module to conduct light, which is beneficial to the miniaturization and integration of the measuring probe.

[0016] Furthermore, the attenuation of the optical fiber in the 500nm to 800nm ​​band is lower than a preset threshold.

[0017] The fluorescence signal generated by the diamond sample containing nitrogen-vacancy centers is in the wavelength band of 500nm to 800nm. The present invention uses an optical fiber with low attenuation (below a preset threshold) in the wavelength band of 500nm to 800nm ​​as a light guide module, which can effectively ensure the fluorescence collection efficiency.

[0018] Furthermore, the magnetic amplification unit is a frustum structure.

[0019] In the magnetic amplification area, the vector magnetic field mapping relationship before and after amplification is closely related to the geometric dimensions of the magnetic amplification unit. In the present invention, the magnetic amplification unit is a truncated cone structure, so the calibration of the vector magnetic field mapping relationship before and after amplification in the magnetic amplification area is relatively simple.

[0020] Furthermore, the magnetic sensitive detector and the end of the light guide module are entirely coated with a reflective film.

[0021] In the vector magnetic field probe provided by the present invention, the magnetically sensitive detector and the end of the light-guiding module are entirely coated with a reflective film, which can reflect the fluorescence generated by the magnetically sensitive detector to the side where the magnetically sensitive detector contacts the light-guiding module. Ultimately, most of the fluorescence is transmitted along the light-guiding module, thereby improving the fluorescence collection efficiency.

[0022] Furthermore, during operation, the magnetically sensitive detector is located at the center of the magnetic amplification area.

[0023] In the vector magnetic field probe provided by the present invention, the vector magnetic field can be best amplified at the center of the magnetic amplification area. The present invention enables the magnetic sensitive detector to be located at the center of the magnetic amplification area during operation, thereby obtaining greater magnetic field sensitivity. In addition, the mapping relationship between the vector magnetic fields before and after amplification at the center of the magnetic amplification area is easy to obtain.

[0024] Furthermore, the relative magnetic permeability of the material of the magnetic amplification unit is greater than 5000.

[0025] In the vector magnetic field probe provided by the present invention, the material of the magnetic amplification unit is a high magnetic permeability material with a relative magnetic permeability greater than 5000, thereby ensuring a good amplification effect on the vector magnetic field.

[0026] Furthermore, the concentration of nitrogen-vacancy centers in diamond is greater than 10 ppb.

[0027] In the vector magnetic field probe provided by the present invention, the nitrogen-vacancy center concentration of the magnetically sensitive detector is relatively high (greater than 10 ppb), thereby ensuring a good signal-to-noise ratio of the measured signal.

[0028] Furthermore, the control field generator is a radio frequency transmission line or an electromagnetic wave radiation structure;

[0029] And / or, the magnetic field generator is a permanent magnet, an energized coil, or an energized solenoid.

[0030] According to another aspect of the present invention, a vector magnetic field measurement method based on the above-mentioned vector magnetic field probe is provided, comprising:

[0031] Calibration step: using the placement point of the magnetic sensitive detector in the magnetic amplification area during operation as a measurement point, calibrating at least three nitrogen-vacancy center axes in the magnetic sensitive detector, and calibrating the mapping relationship between the vector magnetic field before and after amplification at the measurement point;

[0032] Measurement steps: Place the magnetic field amplifier in the vector magnetic field to be measured, and use the magnetic field generator to apply a stable static magnetic field to the magnetic sensitive detector. After the magnetic sensitive detector is placed at the measurement point, use the light guide module to transmit an external laser of a preset wavelength to the magnetic sensitive detector. Use the control field generator to apply a preset electromagnetic field to the magnetic sensitive detector, and collect the fluorescence signal derived from the light guide module.

[0033] Analysis steps: Based on the relationship between the intensity of the fluorescence signal and the change of the electromagnetic field parameters and the calibrated nitrogen-vacancy center axis, the vector magnetic field after amplification is calculated, and based on the mapping relationship between the vector magnetic fields before and after amplification, the vector magnetic field before amplification is determined to complete the measurement of the vector magnetic field to be measured.

[0034] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0035] (1) The vector magnetic field probe provided by the present invention comprises a magnetic field amplifier comprising three pairs of magnetic amplification units that are centrally symmetrical and whose central axes are perpendicular to each other. Based on this structure, the magnetic field amplifier can amplify the vector magnetic field in any direction by a certain multiple, so that the magnetic sensitive detector made of a diamond sample containing nitrogen-vacancy centers has a high detection sensitivity for the vector magnetic field in any direction.

[0036] (2) The present invention uses optical fiber as a light guide module for light conduction, which is conducive to the miniaturization and integration of the measuring probe. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 An overall schematic diagram of a vector magnetic field probe provided by an embodiment of the present invention;

[0038] Figure 2 A schematic structural diagram of a vector magnetic field probe provided in an embodiment of the present invention;

[0039] Figure 3 A schematic diagram of the magnetic field amplification ratio of the magnetic field amplifier in different directions provided by an embodiment of the present invention;

[0040] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0041] 1 is a magnetic sensitive detector, 2 is a light guide module, 3 is a magnetic amplification unit in a magnetic field amplifier, 4 is a magnetic field generator, and 5 is a control field generator. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0043] In the present invention, the terms "first", "second", etc. (if any) in the present invention and the drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0044] To ensure high sensitivity to vector magnetic fields in any direction, the present invention provides a vector magnetic field probe and a vector magnetic field measurement method. The overall concept is to use diamond containing nitrogen-vacancy centers to make a magnetic sensitive probe and specially design the structure of the magnetic field amplifier so that the magnetic field amplifier can amplify the vector magnetic field in any direction at a certain rate.

[0045] The following are examples.

[0046] Example 1:

[0047] A vector magnetic field probe, such as Figures 1 and 2 As shown, it includes: a magnetic sensitive detector 1, a light guide module 2, a control field generator 5, a magnetic field generator 4 and a magnetic field amplifier;

[0048] The magnetic sensitive detector 1 is made of diamond containing nitrogen-vacancy centers and is fixed to the end of the light guide module 2. To meet the requirements of different spatial dimensions, diamond samples of different sizes can be used, ranging from nanometers to millimeters, or even larger. The diamond samples can be in the form of blocks and nanoparticles. Optionally, in this embodiment, a diamond sample with a size of 200μm*200μm*100μm is used as the magnetic sensitive detector 1. In order to ensure a good signal-to-noise ratio of the measured signal, the diamond sample selected in this embodiment contains a nitrogen-vacancy center concentration of at least greater than 10ppb. It is easy to understand that since a nitrogen-vacancy center axis is only sensitive to a magnetic field with the same direction as its direction, in order to ensure that the direction can be measured while measuring the magnitude of the external magnetic field, the diamond sample selected in this embodiment contains at least three nitrogen-vacancy center axes. In actual measurement, at least three of the nitrogen-vacancy center axes will be calibrated in advance according to the placement position of the magnetic sensitive detector 1 in physical space.

[0049] The light guide module 2 is used to transmit an external laser of a preset wavelength to the magnetic sensitive detector 1. Optionally, in this embodiment, the wavelength of the external laser is specifically 532 nm. To facilitate the miniaturization and integration of the measuring probe, as a preferred embodiment, in this embodiment, the light guide module 2 is an optical fiber, specifically a single-mode optical fiber, a multi-mode optical fiber, or another type of optical fiber. The magnetic sensitive detector 1 can be directly attached to the end of the light guide module 2 by an adhesive (such as UV glue or other light-transmitting adhesive) to achieve fixation.

[0050] The control field generator 5 is used to apply a preset electromagnetic field to the magnetic sensitive detector 1. Optionally, in this embodiment, the control field generator 5 is a radio frequency transmission line. In other embodiments of the present invention, the control field generator 5 may also be an electromagnetic wave radiation structure or other structures.

[0051] A magnetic field generator 4 is used to apply a stable static magnetic field to the magnetic sensitive detector 1; the magnetic field generator 4 can be a permanent magnet, a powered coil or a powered solenoid, etc.;

[0052] The magnetic sensitive detector 1 utilizes the property that the nitrogen-vacancy center in diamond is sensitive to magnetic field. The nitrogen-vacancy center is a defect structure in diamond. There are unpaired electrons in the structure, and its ground state is a spin triplet state, which is m s =0, ±1; use 532nm laser to excite nitrogen-vacancy center, if the electron is in m s =0 state, fluorescent photons will be emitted; if the electron is in m s= ±1 state, then there is a high probability that the electron transition will not emit a photon; the external magnetic field in which the nitrogen-vacancy center is located will cause its ground state energy level to split, and the interval of the energy level split is related to the magnitude and direction of the external magnetic field. By applying a control field (i.e., an electromagnetic field), the electron can be controlled to transition between the energy levels of the ground state. Therefore, by controlling the energy level of the electron, the fluorescence intensity emitted by it can be changed, thereby inferring the magnitude and direction of the external magnetic field;

[0053] The solid-state spins within the nitrogen-vacancy center are sensitive to magnetic fields, and the fluorescence emitted after being irradiated by a preset laser and manipulated by a microwave control field can reflect information about the magnetic field to be measured. The light guide module 2 in this embodiment is also used to guide the fluorescence emitted by the magnetically sensitive detector. In practical applications, the other end of the light guide module 2 can be connected to a fluorescence measurement device to obtain the relationship between the intensity of the fluorescence and the change in the parameters of the electromagnetic field; the parameters of the electromagnetic field include one or more of frequency, intensity, and duration.

[0054] The vector magnetic field probe provided in this embodiment includes, in addition to a light guide module 2 for transmitting external laser light and a control field generator 5 for applying a control field, a magnetic field generator 4 for applying a stable static magnetic field. Under the combined action of the external laser, the control field, and the static magnetic field, the fluorescence signal emitted by the magnetically sensitive detector simultaneously carries information on the magnitude and direction of the vector magnetic field. By analyzing the fluorescence signal, the magnitude and direction of the vector magnetic field can be measured simultaneously.

[0055] Considering that the fluorescence signal generated by the diamond sample containing nitrogen-vacancy centers is in the wavelength band of 500nm to 800nm, in order to ensure the collection efficiency of fluorescence, in this embodiment, the attenuation of the optical fiber used as the light guide module 2 in the wavelength band of 500nm to 800nm ​​is lower than a preset threshold; the preset threshold can be set accordingly according to the specific measurement environment and measurement accuracy requirements. The smaller the attenuation, the stronger its light transmission ability. Optionally, in this embodiment, the preset threshold is 10dB / km;

[0056] To further ensure the efficiency of fluorescence collection, in this embodiment, the ends of the magnetic sensitive detector 1 and the light guide module 2 are entirely coated with a reflective film. This can reflect the fluorescence generated by the magnetic sensitive detector 1 to the side of the magnetic sensitive detector 1 that contacts the light guide module 2. Ultimately, most of the fluorescence is transmitted along the light guide module 2, thereby further improving the efficiency of fluorescence collection.

[0057] In order to effectively amplify the vector magnetic field in any direction, in this embodiment, the magnetic field amplifier is as follows: Figure 2As shown, it includes three pairs of magnetic amplification units 3 that are centrally symmetrical and whose central axes are perpendicular to each other. In the cross-section of the magnetic amplification unit 3 along the central axis, the closer the cross-section is to the center of symmetry, the smaller it is, so as to ensure effective amplification of the magnetic field. The area enclosed by the plane where the minimum cross-section of each magnetic amplification unit 3 is located is the magnetic amplification area. Within this magnetic amplification area, the external vector magnetic field in any direction can be effectively amplified.

[0058] In order to facilitate the calibration of the magnetic field amplification area, the vector magnetic field mapping relationship before and after amplification is as follows: Figure 2 As shown, in this embodiment, the magnetic amplification unit 3 is specifically a truncated cone structure, and the diameter of the smaller end face, the diameter of the larger end face, and the height thereof are respectively denoted as d, D, and h. The distance between the two magnetic amplification units 3 in each pair of magnetic amplification units 3 is denoted as L. In this embodiment, the specific dimensions of the truncated cone structure are d=2mm, D=60mm, h=60mm, and L=2mm. In order to ensure a good amplification effect on the vector magnetic field, in this embodiment, the magnetic amplification unit 3 is made of a material with a relatively large relative magnetic permeability. Specifically, the relative magnetic permeability of the material of the magnetic amplification unit 3 is greater than 5000.

[0059] It should be noted that the shape and size of the magnetic amplification unit 3 described here are only exemplary descriptions and should not be understood as the only limitation to the present invention. In some other embodiments of the present invention, the size of the magnetic amplification unit can be adjusted accordingly according to the actual application scenario; in some other embodiments of the present invention, the frustum structure may not be used, and other structures that can achieve magnetic field amplification may be used, which will not be listed one by one here.

[0060] During operation, the magnetic field amplifier is located in the vector magnetic field to be measured, and the magnetic sensitive detector 1 is located in the magnetic amplification area. In order to simplify the analysis, during measurement, the magnetic sensitive detector is preferably placed in the center of the magnetic amplification area, that is, Figure 2 Point O in the image; under the combined action of external laser, electromagnetic field and static magnetic field, the magnetic sensitive detector emits fluorescence that carries information about the magnitude and direction of the vector magnetic field;

[0061] The symmetry point of the magnetic amplifier is Figure 2 Point O is a circle, and the vector magnetic field H to be measured tar The distribution intensity in all directions is, H x =H0 sin(b)*cos(a), H y =H0 sin(b)*sin(a),H z =H0*cos(b), where 0≤a≤2π, 0≤b≤π, H0=10A / m, where H0 represents the magnitude of the vector magnetic field to be measured, a and b are the angles of the vector field to be measured when expressed in spherical coordinates, and A / m is the unit of magnetic field; Figure 3 The magnetic field amplifier is used to measure the vector magnetic field H.tar The magnification of Figure 3 It can be seen that the magnifications are all above 45, that is, the magnification of this embodiment can be guaranteed to a certain extent for magnetic fields in any direction.

[0062] In the vector magnetic field probe provided by the present invention, the material of the magnetic amplification unit is a high magnetic permeability material with a relative magnetic permeability greater than 5000, thereby ensuring a good amplification effect on the vector magnetic field.

[0063] Example 2:

[0064] A vector magnetic field measurement method based on the above-mentioned vector magnetic field probe includes:

[0065] Calibration step: using the placement point of the magnetic sensitive detector in the magnetic amplification area during operation as a measurement point, calibrating at least three nitrogen-vacancy center axes in the magnetic sensitive detector, and calibrating the mapping relationship between the vector magnetic field before and after amplification at the measurement point;

[0066] Measurement steps: Place the magnetic field amplifier in the vector magnetic field to be measured, and use the magnetic field generator to apply a stable static magnetic field to the magnetic sensitive detector. After the magnetic sensitive detector is placed at the measurement point, use the light guide module to transmit an external laser of a preset wavelength to the magnetic sensitive detector. Use the control field generator to apply a preset electromagnetic field to the magnetic sensitive detector, and collect the fluorescence signal derived from the light guide module.

[0067] Analysis steps: Based on the relationship between the intensity of the fluorescence signal and the change of the electromagnetic field parameters and the calibrated nitrogen-vacancy center axis, the vector magnetic field after amplification is calculated, and based on the mapping relationship between the vector magnetic fields before and after amplification, the vector magnetic field before amplification is determined to complete the measurement of the vector magnetic field to be measured.

[0068] In the analysis step, the parameters of the selected electromagnetic field may be one or more of frequency, intensity, and duration; taking frequency as an example, in the measurement step, a control field generator is used to apply a preset electromagnetic field with a variable frequency to the magnetic sensitive detector. When an external magnetic field is applied to the magnetic sensitive detector, the external magnetic field will cause the energy level of the magnetic sensitive detector to split, and the magnitude of the energy level splitting is related to the direction and intensity of the magnetic field. By applying a preset electromagnetic field to the magnetic sensitive detector and then reading the fluorescence signal after the laser, we can obtain the energy level splitting of the magnetic sensitive detector. After obtaining the energy level splitting, we can infer the magnitude of the magnetic field to be measured.

[0069] In actual measurements, other electromagnetic field parameters can also be selected, such as a combination of frequency and intensity, or a combination of frequency and duration, etc. In the measurement step, an electromagnetic field with variable parameters is applied accordingly, and the magnitude of the vector magnetic field can be measured based on the relationship between the fluorescence signal and the changes in these parameters.

[0070] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A vector magnetic field probe, characterized in that: include: Magnetic sensitive detector, light guide module, control field generator, magnetic field generator and magnetic field amplifier; The magnetic sensitive detector is made of diamond containing nitrogen-vacancy centers and is fixed to the end of the light guide module; the light guide module is used to transmit external laser light of a preset wavelength to the magnetic sensitive detector; the control field generator is used to apply a preset electromagnetic field to the magnetic sensitive detector; the magnetic field generator is used to apply a stable static magnetic field to the magnetic sensitive detector; The magnetic field amplifier comprises three pairs of magnetic amplification units that are centrally symmetrical and whose central axes are perpendicular to each other; in the cross-section of the magnetic amplification units along the central axis, the closer the cross-section is to the symmetry center, the smaller the cross-section is, and the area enclosed by the plane where the minimum cross-section of each magnetic amplification unit is located is the magnetic amplification area; During operation, the magnetic field amplifier is located within the vector magnetic field to be measured, and the magnetically sensitive detector is located within the magnetic amplification area; under the combined action of the external laser, the electromagnetic field, and the static magnetic field, the magnetically sensitive detector emits fluorescence carrying information on the magnitude and direction of the vector magnetic field; the light guide module is also used to guide the fluorescence emitted by the magnetically sensitive detector.

2. The vector magnetic field probe according to claim 1, wherein: The light guide module is an optical fiber.

3. The vector magnetic field probe according to claim 2, wherein: The attenuation of the optical fiber in the 500nm to 800nm ​​band is lower than a preset threshold.

4. The vector magnetic field probe according to any one of claims 1 to 3, characterized in that: The magnetic amplification unit is a truncated cone structure.

5. The vector magnetic field probe according to any one of claims 1 to 3, characterized in that: The magnetic sensitive detector and the end of the light guide module are entirely plated with a reflective film.

6. The vector magnetic field probe according to any one of claims 1 to 3, characterized in that: During operation, the magnetically sensitive detector is located at the center of the magnetic amplification area.

7. The vector magnetic field probe according to any one of claims 1 to 3, characterized in that: The relative magnetic permeability of the material of the magnetic amplification unit is greater than 5000.

8. The vector magnetic field probe according to any one of claims 1 to 3, characterized in that: The diamond has a nitrogen-vacancy center concentration greater than 10 ppb.

9. The vector magnetic field probe according to any one of claims 1 to 3, characterized in that: The control field generator is a radio frequency transmission line or an electromagnetic wave radiation structure; And / or, the magnetic field generator is a permanent magnet, an energized coil or an energized solenoid.

10. A vector magnetic field measurement method based on the vector magnetic field probe according to any one of claims 1 to 9, characterized in that: include: Calibration step: using the placement point of the magnetic sensitive detector in the magnetic amplification area during operation as a measurement point, calibrating at least three nitrogen-vacancy center axes in the magnetic sensitive detector, and calibrating the mapping relationship between the vector magnetic field before and after amplification at the measurement point; Measuring steps: placing the magnetic field amplifier in the vector magnetic field to be measured, applying a stable static magnetic field to the magnetic sensitive detector using the magnetic field generator, after the magnetic sensitive detector is placed at the measuring point, transmitting an external laser of a preset wavelength to the magnetic sensitive detector using the light guide module, applying a preset electromagnetic field to the magnetic sensitive detector using the control field generator, and collecting the fluorescence signal derived from the light guide module; Analysis steps: Based on the relationship between the intensity of the fluorescence signal and the change in the parameters of the electromagnetic field and the calibrated nitrogen-vacancy center axis, the amplified vector magnetic field is calculated, and based on the mapping relationship between the vector magnetic fields before and after amplification, the vector magnetic field before amplification is determined to complete the measurement of the vector magnetic field to be measured.

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