Magnetic field measuring device and magnetic field measuring method

Abstract

To efficiently apply a magnetic field corresponding to a magnetic field to be measured with a flux transformer (FT) to a magnetic resonance member, for magnetic field measurement.SOLUTION: A high-frequency magnetic field generator 2 applies microwaves to a magnetic resonance member 1. A magnet 3 applies a static magnetic field to the magnetic resonance member 1. An irradiation device 12 irradiates the magnetic resonance member 1 with incident light of a specific wavelength. A FT 4 senses a magnetic field to be measured with a primary side coil 4a, and applies an applied magnetic field corresponding to the sensed magnetic field to be measured to the magnetic resonance member 1 with a secondary side coil 4b. A columnar light guide member 41 guides the incident light to the magnetic resonance member 1, and a columnar light guide member 42 guides fluorescence emitted by the magnetic resonance member 1 from the magnetic resonance member 1. The magnetic resonance member 1 is sandwiched between the end surface of the light guide member 41 and the end surface of the light guide member 42 in a hollow part of the secondary coil 4b of the FT 4 and a hollow part of said magnet 3.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a magnetic field measuring device and a magnetic field measuring method. [Background technology]

[0002] A certain magnetic field measuring device performs magnetic measurement by optically detected magnetic resonance (ODMR) using the electron spin resonance of a sensing member such as a diamond structure having nitrogen and lattice defects (NV center) (see, for example, Patent Document 1). In ODMR, a static magnetic field is applied to a magnetic resonance member such as diamond having such an NV center in addition to the magnetic field to be measured, and laser light (excitation light and measurement light) and microwaves are applied in a predetermined sequence, the amount of fluorescent light emitted from the magnetic resonance member is detected, and the magnetic flux density of the magnetic field to be measured is derived based on the amount of light.

[0003] For example, in the Ramsey pulse sequence, (a) excitation light is applied to the NV center, (b) a first π / 2 pulse of microwaves is applied to the NV center, (c) a second π / 2 pulse of microwaves is applied to the NV center at a predetermined time interval tt from the first π / 2 pulse, (d) measurement light is applied to the NV center to measure the amount of light emitted by the NV center, and (e) the magnetic flux density is derived based on the measured amount of light emitted. Also, in the spin echo pulse sequence, (a) excitation light is applied to the NV center, (b) a first π / 2 pulse of microwaves is applied to the NV center at a phase of 0 degrees of the measured magnetic field, (c) a π pulse of microwaves is applied to the NV center at a phase of 180 degrees of the measured magnetic field, (d) a second π / 2 pulse of microwaves is applied to the NV center at a phase of 360 degrees of the measured magnetic field, (e) measurement light is applied to the NV center to measure the amount of light emitted by the NV center, and (f) the magnetic flux density is derived based on the measured amount of light emitted.

[0004] Furthermore, one magnetic sensor includes a superconducting quantum interference device (SQUID) and a flux transformer that detects the magnetic field to be measured using a pickup coil and applies it to the SQUID using an input coil (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-8298 A [Patent Document 2] Japanese Patent Application Publication No. 8-75834 Summary of the Invention [Problem to be solved by the invention]

[0006] The above-mentioned magnetic field measuring device applies a laser beam, a microwave, and a static magnetic field to the magnetic resonance member in addition to the magnetic field to be measured, and therefore, means for applying the laser beam, the microwave, and the static magnetic field are mounted around the magnetic resonance member. Therefore, when applying the laser beam, the microwave, and the static magnetic field to the magnetic resonance member, in order to use a flux transformer, it is necessary to arrange the secondary coil of the flux transformer without interfering with the application of the laser beam, the microwave, and the static magnetic field, and due to the geometrical configuration, it is difficult for the flux transformer to efficiently apply a magnetic field corresponding to the magnetic field to be measured to the magnetic resonance member.

[0007] The present invention has been made in consideration of the above problems, and aims to provide a magnetic field measuring device and a magnetic field measuring method in which a magnetic field corresponding to the magnetic field to be measured is efficiently applied to a magnetic resonance component by a flux transformer, and the magnetic resonance component, high-frequency magnetic field generator, and magnet are easily arranged relative to the direction of the magnetic flux of the flux transformer, making it easy to secure space for irradiating laser light. [Means for solving the problem]

[0008] The magnetic field measuring device according to the present invention includes a magnetic resonance member capable of performing electron spin quantum manipulation with microwaves, a high-frequency magnetic field generator for applying microwaves to the magnetic resonance member, a magnet for applying a static magnetic field to the magnetic resonance member, an irradiation device for irradiating the magnetic resonance member with incident light of a specific wavelength, a flux transformer for sensing a magnetic field to be measured with a primary coil and applying an applied magnetic field corresponding to the sensed magnetic field to the magnetic resonance member with a secondary coil, a cylindrical first light guiding member for guiding the incident light to the magnetic resonance member, and a cylindrical second light guiding member for guiding the fluorescence emitted by the magnetic resonance member from the magnetic resonance member. The magnetic resonance member is sandwiched between an end face of the first light guiding member and an end face of the second light guiding member in a hollow part of the secondary coil of the flux transformer and a hollow part of the magnet.

[0009] The magnetic field measuring method according to the present invention includes: (a) sensing a magnetic field to be measured with a primary coil of a flux transformer; (b) applying an applied magnetic field corresponding to the sensed magnetic field to be measured with a secondary coil of the flux transformer to a magnetic resonance member capable of electron spin quantum manipulation with microwaves; applying microwaves to the magnetic resonance member; applying a static magnetic field to the magnetic resonance member; guiding incident light of a specific wavelength from an irradiation device to the magnetic resonance member with a cylindrical first light guiding member; guiding fluorescence emitted by the magnetic resonance member from the magnetic resonance member with a cylindrical second light guiding member; A static magnetic field is applied to the magnetic resonance member. In the hollow portion of the magnet, the magnet is disposed between an end face of the first light guide member and an end face of the second light guide member. Effect of the Invention

[0010] According to the present invention, a magnetic field measuring device and a magnetic field measuring method are obtained in which a magnetic field corresponding to the magnetic field to be measured is efficiently applied to a magnetic resonance component by a flux transformer, and the magnetic resonance component, high-frequency magnetic field generator, and magnet are easily arranged relative to the direction of the magnetic flux of the flux transformer, making it easy to secure space for irradiating laser light. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing a configuration of a magnetic field measuring device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing the primary coil 4a of the transformer 4 in FIG. [Diagram 3] FIG. 3 is a diagram for explaining the arrangement of the primary coil 4a of the transformer 4 during magnetic field measurement. [Figure 4] FIG. 4 is a perspective view showing an example of the configuration of the magnetic sensor unit 10 shown in FIG. [Diagram 5] FIG. 5 is a perspective cross-sectional view showing an example of the configuration of the magnetic sensor unit 10 shown in FIG. [Figure 6] FIG. 6 is a side view showing an example of the configuration of an optical system in the magnetic sensor unit 10 shown in FIG. [Figure 7] FIG. 7 is a cross-sectional view showing an example of a light-guiding member and a magnetic resonance member in a magnetic field measuring device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] Embodiment 1

[0014] Fig. 1 is a block diagram showing the configuration of a magnetic field measuring device according to an embodiment of the present invention. The magnetic field measuring device shown in Fig. 1 includes a magnetic sensor unit 10, a high-frequency power supply 11, an irradiation device 12, a light receiving device 13, and a calculation processing device 14.

[0015] The magnetic sensor unit 10 detects a magnetic field to be measured (e.g., the strength and direction of the magnetic field) at a predetermined position (e.g., on or above the surface of an object to be inspected). The magnetic field to be measured may be an alternating magnetic field of a single frequency, or an alternating magnetic field of a predetermined period having multiple frequency components.

[0016] In this embodiment, the magnetic sensor section 10 comprises a magnetic resonance member 1 , a high-frequency magnetic field generator 2 , a magnet 3 , and a flux transformer 4 .

[0017] The magnetic resonance member 1 has a crystal structure and is capable of quantum manipulation of electron spins (based on Rabi oscillations) using microwaves with a frequency that corresponds to the arrangement direction of defects and impurities in the crystal lattice.

[0018] In this embodiment, the magnetic resonance component 1 is a light-detecting magnetic resonance component having a plurality (i.e., an ensemble) of specific color centers. The specific color centers have energy levels that can be Zeeman split, and can take a plurality of orientations in which the energy level shift widths during Zeeman splitting are different from one another.

[0019] Here, the magnetic resonance member 1 is a member such as diamond that contains multiple NV (Nitrogen Vacancy) centers as a single type of specific color center. In the case of the NV center, the ground state is a triplet state of ms=0, +1, -1, and the level of ms=+1 and the level of ms=-1 are Zeeman split. Note that the color center contained in the magnetic resonance member 1 may be a color center other than the NV center.

[0020] The high frequency magnetic field generator 2 applies the above-mentioned microwaves to the magnetic resonance member 1 .

[0021] Moreover, the magnet 3 applies a static magnetic field (a direct current magnetic field) to the magnetic resonance member 1. Here, the magnet 3 is a ring-shaped permanent magnet, such as a ferrite magnet, an alnico magnet, or a samarium-cobalt magnet.

[0022] The magnetic resonance member 1 includes a plurality of color centers (here, NV centers) capable of quantum manipulation of electron spins by the above-mentioned microwaves, and the magnet 3 applies a substantially uniform static magnetic field to a predetermined region (irradiation region of the excitation light and the measurement light) of the magnetic resonance member 1, and Zeeman-splits the energy levels of the plurality of specific color centers (here, a plurality of NV centers) in the magnetic resonance member 1. For example, the static magnetic field is applied so that the difference or ratio between the maximum and minimum values ​​of the intensity of the static magnetic field in the predetermined region is equal to or less than a predetermined value.

[0023] In the case of NV centers, color centers are formed in diamond crystals by defects (vacancies) (V) and nitrogen (N) as impurities, and there are four possible positions of adjacent nitrogen (N) relative to the defects (vacancies) (V) in the diamond crystal (i.e., the arrangement direction of pairs of vacancies and nitrogen), and the sublevels (i.e., the energy levels from the ground level) after Zeeman splitting corresponding to each of these arrangement directions are different from each other. Therefore, in the characteristics of the fluorescence intensity after Zeeman splitting by the static magnetic field against the microwave frequency, four different dip frequency pairs (fi+, fi-) appear corresponding to each direction i (i=1,2,3,4). Here, the frequency (wavelength) of the microwave described above is set corresponding to one of the dip frequencies among these four dip frequency pairs.

[0024] The flux transformer 4 includes a primary coil 4a and a secondary coil 4b electrically connected to the primary coil 4a by a cable (coaxial cable, Litz wire, etc.). As shown in FIG. 2, the primary coil 4a is configured with a winding of 0.5 to several tens of turns. As shown in FIG. 3, the primary coil 4a senses a magnetic field to be measured at a predetermined measurement position above the object 101 to be measured, for example, and the secondary coil 4b applies an applied magnetic field (magnetic field transmitted from the measurement position by the flux transformer 4) corresponding to the magnetic field to be measured sensed at the measurement position to the magnetic resonance member 1. That is, the primary coil 4a induces an electric signal corresponding to the sensed magnetic field to be measured, and the secondary coil 4b induces an applied magnetic field corresponding to the electric signal.

[0025] Furthermore, an irradiation device 12 and a light receiving device 13 are provided as detection devices for detecting fluorescence generated from the magnetic resonance component 1 by a physical phenomenon corresponding to the above-mentioned applied magnetic field.

[0026] The irradiation device 12 generates laser light (here, excitation light of a predetermined wavelength for ODMR and measurement light of a predetermined wavelength) to be irradiated to the magnetic resonance component 1, and irradiates the laser light to the magnetic resonance component 1 as a light detection magnetic resonance component via an optical system described below.

[0027] Furthermore, the light receiving device 13 receives and detects the fluorescence emitted from the magnetic resonance component 1 via an optical system described below when the measurement light is irradiated.

[0028] The arithmetic processing device 14 includes, for example, a computer, and executes a program on the computer to operate as various processing units. In this embodiment, the arithmetic processing device 14 stores detected optical or electrical signal data in a storage device (such as a memory) not shown, and performs control and calculation operations as the measurement control unit 21 and the calculation unit 22.

[0029] The measurement control unit 21 controls the high-frequency power supply 11 and identifies the detection value of the above-mentioned physical phenomenon (here, the fluorescence intensity) detected by the above-mentioned detection devices (here, the irradiation device 12 and the light receiving device 13).

[0030] In this embodiment, the measurement control unit 21 controls the high frequency power supply 11 and the irradiating device 12 in accordance with a predetermined measurement sequence based on, for example, ODMR, and identifies the amount of detected fluorescence detected by the light receiving device 13. For example, the irradiating device 12 includes a laser diode or the like as a light source, and the light receiving device 13 includes a photodiode or the like as a light receiving element, and the measurement control unit 21 identifies the above-mentioned amount of detected light based on the output signal of the light receiving device 13 obtained by amplifying the output signal of the light receiving element.

[0031] The calculation unit 22 calculates the measured magnetic field (intensity, waveform, etc.) at the measurement position described above based on the detection values ​​obtained by the measurement control unit 21 and stored in the storage device.

[0032] The above-mentioned measurement sequence is set according to the frequency of the measured magnetic field. For example, when the measured magnetic field is a relatively high-frequency alternating magnetic field, a spin echo pulse sequence (such as a Hahn echo sequence) is applied to this measurement sequence. However, the measurement sequence is not limited to this. Also, for example, when the measured magnetic field is a relatively low-frequency alternating magnetic field, magnetic field measurement may be performed multiple times in one period of the measured magnetic field using a Ramsey pulse sequence (i.e., a measurement sequence of a direct current magnetic field), and the measured magnetic field (intensity, waveform, etc.) may be specified based on the results of these magnetic field measurements.

[0033] The magnetic sensor unit 10 will be described in detail below.

[0034] Fig. 4 is a perspective view showing a configuration example of the magnetic sensor unit 10 shown in Fig. 1. Fig. 5 is a perspective cross-sectional view showing a configuration example of the magnetic sensor unit 10 shown in Fig. 1. Fig. 6 is a side view showing a configuration example of the optical system in the magnetic sensor unit 10 shown in Fig. 1.

[0035] In this embodiment, as shown in Fig. 4 and Fig. 5, for example, the high frequency magnetic field generator 2 is a plate-shaped coil, and includes a substantially circular coil section 2a that emits microwaves into its hollow section, and terminal sections 2b that extend from both ends of the coil section 2a and are fixed to a substrate (not shown) or the like. The high frequency power source 11 generates the microwave current and conducts it to the high frequency magnetic field generator 2. The coil section 2a of the high frequency magnetic field generator 2 conducts two parallel currents at a predetermined interval at both end surfaces of the coil section 2a so as to sandwich the magnetic resonance member 1, and emits the above-mentioned microwaves. Here, the high frequency magnetic field generator 2 is a plate-shaped coil, but due to the skin effect, the microwave current flows through the end surfaces of the coil section 2a, so that two currents are formed.

[0036] As shown in FIGS. 4 to 6, the magnetic sensor unit 10 further includes a bobbin 4b1 around which the secondary coil 4b is wound, and light guide members 41 and .

[0037] The light-guiding member 41 is a columnar (here, rectangular prism-shaped) member that transmits light and guides incident light from the irradiation device 12 to the magnetic resonance member 1. The light-guiding member 42 is a columnar (here, rectangular prism-shaped) member that transmits light and guides fluorescence emitted by the magnetic resonance member 1 from the magnetic resonance member 1 toward the light-receiving device 13. The light-guiding members 41 and 42 are, for example, glass members, and have cross sections of the same shape in a direction perpendicular to the longitudinal direction.

[0038] The magnetic resonance member 1 is disposed in the hollow portion of the secondary coil 4b of the flux transformer 4 and in the hollow portion of the magnet 3, being sandwiched between an end face of the light-guiding member 41 and an end face of the light-guiding member .

[0039] Specifically, the magnetic resonance member 1 has a substantially rectangular plate-like shape, and one of two opposing faces of the magnetic resonance member 1 is in surface contact with or surface-bonded (for example, with an adhesive) to an end face of the light-guiding member 41, and the other face is in surface contact with or surface-bonded (for example, with an adhesive) to an end face of the light-guiding member 42. In this way, the light-guiding members 41, 42 and the magnetic resonance member 1 are arranged on a straight line.

[0040] The secondary coil 4b is wound in a ring shape around a non-magnetic bobbin 4b1 at a predetermined turns ratio with respect to the primary coil 4a, and the secondary coil 4b wound around the bobbin 4b1 is disposed in a hollow portion of a substantially circular and plate-shaped coil section 2a of the high frequency magnetic field generator 2, as shown in Fig. 4 and Fig. 5, for example. The bobbin 4b1 has a through hole 4b2 along the central axis of the secondary coil 4b. The bobbin 4b1 (its bottom surface 4b3) is fixed to a structure such as a substrate so that the through hole 4b2 (its center) is disposed at the center of the coil section 2a of the high frequency magnetic field generator 2 and substantially perpendicular to the central axis of the coil section 2a.

[0041] In addition, openings 2c, 2d are formed on the side surface of the approximately circular, plate-shaped coil section 2a in the high-frequency magnetic field generator 2, and the openings 2c, 2d are located in the axial direction of the secondary coil 4b when viewed from the secondary coil 4b, and are positioned opposite each other via the center of the coil section 2a in a direction approximately perpendicular to the central axial direction of the coil section 2a.

[0042] As a result, the direction of the microwaves (magnetic field) from the high frequency magnetic field generator 2 becomes approximately perpendicular to the direction of the magnetic field from the secondary coil 4b. The angle between the direction of the microwaves (magnetic field) from the high frequency magnetic field generator 2 and the direction of the magnetic field from the secondary coil 4b is preferably within a range of 90 degrees ±8 degrees, and is most preferably 90 degrees.

[0043] The size of the openings 2c and 2d is determined by the size of the irradiation area in the magnetic resonance member 1 and the size of the area in which current flows in the coil section 2a under the skin effect. In this embodiment, the irradiation area in the magnetic resonance member 1 is rectangular or circular, and the plate coil of the high-frequency magnetic field generator 2 is approximately circular, so that the openings 2c and 2d are arc-shaped rectangles, and the openings 2c and 2d are designed so that the area of ​​the projection area of ​​the openings 2c and 2d onto the magnetic resonance member 1 is larger than the area of ​​the irradiation area and the projection area includes the irradiation area.

[0044] The plate-shaped magnetic resonance member 1 and the columnar light-guiding members 41, 42 are arranged in the through hole 4b2 and the openings 2c, 2d, and at least the light-guiding members 41, 42 (or the magnetic resonance member 1 and the light-guiding members 41, 42) are supported and fixed in the through hole 4b2.

[0045] In addition, in this embodiment, as shown in FIG. 4, the magnet 3 is a ring-shaped magnet, the secondary coil 4b is wound in a ring shape, the central axis of the magnet 3 and the central axis of the secondary coil 4b coincide with each other, and the magnetic resonance member 1, the light-guiding member 41, and the light-guiding member 42 are arranged on the central axis.

[0046] For example, as shown in FIG. 4, the above-mentioned magnetic resonance member 1 is disposed in a position in the hollow portion of the secondary coil 4b of the flux transformer 4 and in the hollow portion of the magnet 3. In this embodiment, the secondary coil 4b is disposed in the hollow portion of the magnet 3. The magnetic resonance member 1 is disposed within a central area of ​​a radius=(radius of the transverse section×a%) from the center point in each transverse section perpendicular to the central axis of the magnet 3 and the central axis of the secondary coil 4b. In particular, it is preferable that the magnetic resonance member 1 is disposed at the center point. Here, a is 30 or less, more preferably 20 or less, even more preferably 10 or less, and even more preferably 5 or less.

[0047] Therefore, in this embodiment, the direction of application of the above-mentioned magnetic field by the secondary coil 4b is the same as the direction of application of the above-mentioned static magnetic field by the magnet 3, and application of the above-mentioned static magnetic field enhances the change in fluorescence intensity at the above-mentioned dip frequency, thereby increasing sensitivity.

[0048] Furthermore, in the magnetic resonance member 1, the crystals of the magnetic resonance member 1 are formed and the orientation of the magnetic resonance member 1 is set so that the arrangement direction of the above-mentioned defects and impurities approximately coincides with the direction of the above-mentioned static magnetic field (and the direction of the applied magnetic field).

[0049] The angle (absolute value) between the arrangement direction of the defects and impurities and the direction of the static magnetic field (and the direction of the applied magnetic field) is preferably 8 degrees or less, and most preferably 0 degrees. The angle (absolute value) between the direction of the static magnetic field and the direction of the applied magnetic field is preferably 8 degrees or less, and most preferably 0 degrees.

[0050] Furthermore, in the direction of the central axis of the magnet 3, the magnetic resonance member 1 is disposed in a central region of the width of the ring-shaped magnet 3. The "central region" here refers to a space of ±(1 / 2×b%) of the central axis length from the center point of the central axis of the ring-shaped magnet 3 along the central axis direction. Here, b is 30 or less, more preferably 20 or less, even more preferably 10 or less, and even more preferably 5 or less.

[0051] In this embodiment, the magnetic resonance member 1 is disposed at the center of the width of the ring-shaped magnet 3 (i.e., the magnetic resonance member 1 is disposed at a position approximately equidistant from both end faces of the magnet 3). Furthermore, in the direction of the central axis of the secondary coil 4b of the transformer 4, the magnetic resonance member 1 is disposed in a central region of the width of the secondary coil 4b. The "central region" here refers to a space of ±(1 / 2×c%) of the central axis from the center point of the central axis of the secondary coil 4b along the central axis direction. Here, c is 30 or less, more preferably 20 or less, even more preferably 10 or less, and even more preferably 5 or less. In this embodiment, the magnetic resonance member 1 is disposed at the center of the width of the secondary coil 4b (i.e., the magnetic resonance member 1 is disposed at a position approximately equidistant from both end faces of the secondary coil 4b). Furthermore, in a plane perpendicular to the central axis of the hollow part of the magnet 3, the cross-sectional area of ​​the hollow part is preferably 100 times or more the area of ​​the irradiation area of ​​the excitation light and the measurement light in the magnetic resonance component 1, and in particular, in the cross section of the hollow part, the diameter length in the radial direction is preferably 10 times or more the diameter of the irradiation area of ​​the measurement light. In this embodiment, for example, the irradiation area of ​​the measurement light is 50 μm×100 μm, and the cross-sectional area of ​​the hollow part is 500 μm×1000 μm or more. In this way, a uniform static magnetic field (a static magnetic field with approximately constant direction and strength) is applied to the irradiation area of ​​the excitation light and the measurement light.

[0052] Further, the fluorescence emitted by the magnetic resonance member 1 is collected from the magnetic resonance member 1 toward the light receiving device 13 via a light guiding member 42 and a predetermined optical system 43, as shown in FIG. 6, for example. In this embodiment, the optical system 43 includes compound parabolic concentrators (CPCs) 43a, 43b, as shown in FIG. 6, for example. The optical system 43 may have other lens configurations. An end face of the light guiding member 42 is in surface contact with or surface-bonded (for example, with an adhesive) to an end face of the CPC 43a, and the fluorescence guided by the light guiding member 42 enters the inside of the CPC 43a through this end face.

[0053] The optical system 43 is configured to prevent the incident light (i.e., the residual component transmitted through the magnetic resonance member 1) from being incident on the light receiving device 13. Specifically, for example, as shown in Fig. 6, a dichroic mirror 43c that transmits the fluorescence and reflects the incident light and / or a long pass filter 43d that transmits the fluorescence and attenuates the incident light is provided in the optical system 43. The incident light reflected by the dichroic mirror 43c is detected by the reference light receiving device 13a, and the calculation unit 22 corrects the measurement value of the magnetic field to be measured based on the amount of incident light detected by the reference light receiving device 13a (e.g., deviation from a predetermined reference amount of light, etc.).

[0054] In this embodiment, the irradiation device 12 irradiates the magnetic resonance member 1 with the above-mentioned incident light along the above-mentioned central axis via the light guiding member 41. As a result, the incident light enters the light guiding member 41 from the end face 41a of the light guiding member 41, and travels toward the magnetic resonance member 1 while being reflected by the side face of the light guiding member 41. In this way, the light guiding member 41 ensures a space through which the optical path of the laser light (measurement light) from the irradiation device 12 and the optical path of the fluorescence from the magnetic resonance member 1 pass, and the measurement light and fluorescence are prevented from leaking into the external space.

[0055] A magnetic shield is provided around the magnetic resonance member 1 in the magnetic sensor unit 10 so that an external magnetic field is not directly applied to the magnetic resonance member 1.

[0056] Next, the operation of the magnetic field measuring device according to this embodiment will be described.

[0057] 3, for example, the primary coil 4a of the flux transformer 4 in the magnetic sensor unit 10 is disposed in a desired measurement position and in a desired orientation with respect to the measured object 101. As a result, the measured magnetic field is sensed by the primary coil 4a, and an applied magnetic field is induced by the secondary coil 4b and applied to the magnetic resonance member 1. In addition, a substantially uniform static magnetic field is applied to the magnetic resonance member 1 by the magnet 3 in the magnetic sensor unit 10.

[0058] Then, the measurement control unit 21 controls the high-frequency power supply 11 and the irradiation device 12 to apply microwaves from the high-frequency magnetic field generator 2 to the magnetic resonance member 1 according to a predetermined measurement sequence, and also applies laser light (excitation light and measurement light) from the irradiation device 12 to the magnetic resonance member 1 via the light guiding member 41. The light receiving device 13 receives the fluorescence from the magnetic resonance member 1 emitted in response to the excitation light and measurement light via the light guiding member 42 and the optical system 43, and outputs an electrical signal corresponding to the amount of light (fluorescence intensity) of the fluorescence. The measurement control unit 21 acquires the electrical signal, and the calculation unit 22 performs calculations corresponding to the measurement sequence based on the detected value of the fluorescence intensity, to identify the magnetic field (intensity, direction, etc.) at the measurement position.

[0059] As a result, the magnetic field at the measurement position is measured by the magnetic sensor unit 10 (i.e., the magnetic resonance member 1). Note that the magnetic sensor unit 10 may be scanned along a predetermined scanning path pattern to perform the above-mentioned magnetic field measurement at a plurality of measurement positions on the scanning path.

[0060] As described above, according to the first embodiment, the high-frequency magnetic field generator 2 applies microwaves to the magnetic resonance member 1 capable of performing electron spin quantum manipulation with microwaves. The magnet 3 applies a static magnetic field to the magnetic resonance member 1. The irradiation device 12 irradiates the magnetic resonance member 1 with incident light of a specific wavelength. The flux transformer 4 senses the magnetic field to be measured with the primary coil 4a, and applies an applied magnetic field corresponding to the sensed magnetic field to be measured to the magnetic resonance member 1 with the secondary coil 4b. The columnar light guiding member 41 guides the incident light to the magnetic resonance member 1, and the columnar light guiding member 42 guides the fluorescence emitted by the magnetic resonance member 1 from the magnetic resonance member 1. The magnetic resonance member 1 is disposed in the hollow portion of the secondary coil 4b of the flux transformer 4 and in the hollow portion of the magnet 3 described above, sandwiched between the end face of the light guiding member 41 and the end face of the light guiding member 42.

[0061] This allows a magnetic field corresponding to the magnetic field to be measured to be applied to the magnetic resonance member 1 together with a static magnetic field without interfering with the optical paths of the above-mentioned excitation light and measurement light (as well as fluorescence). Therefore, the magnetic field corresponding to the magnetic field to be measured can be efficiently applied to the magnetic resonance member 1 by the flux transformer 4 to perform magnetic field measurement. In addition, it becomes easier to relatively arrange the magnetic resonance member 1, the high-frequency magnetic field generator 2, and the magnet 3, and the magnetic flux direction of the flux transformer 4, and further, it becomes easier to ensure a space for irradiating the laser light.

[0062] Next, a method for manufacturing the magnetic field measuring device according to this embodiment will be described.

[0063] First, the magnetic resonance member 1, the high-frequency magnetic field generator 2, the magnet 3, and the flux transformer 4 are prepared.

[0064] Next, the high frequency magnetic field generator 2 is attached to a circuit board (not shown). From the viewpoint of miniaturization, when a semiconductor substrate such as SiC is used, the high frequency magnetic field generator 2 is integrally mounted on the substrate.

[0065] Next, the circuit board is fixed to fix the high frequency magnetic field generator 2, and the secondary coil 4b of the flux transformer 4 is arranged so that both ends of the through hole 4b2 of the bobbin 4b1 face the openings 2c and 2d of the high frequency magnetic field generator 2. The magnetic resonance component 1 is assembled so that one of the arrangement directions of the defects faces the center of the openings 2c and 2d. This makes the magnetic flux generated from the high frequency magnetic field generator 2 perpendicular to at least one outer surface of the magnetic resonance component 1.

[0066] Then, the light guide member 41, the magnetic resonance member 1, and the light guide member 42 are inserted through the openings 2c and 2d and fixed into the through hole 4b2 of the bobbin 4b1. At this time, the magnetic resonance member 1 is arranged in the central area and central region of the secondary coil 4b. In addition, the orientation and position of each part are adjusted so that the magnetic flux generated from the high frequency magnetic field generator 2 and the magnetic flux generated from the secondary coil 4b are perpendicular to each other.

[0067] Furthermore, a magnet 3 is attached to the outside of the high-frequency magnetic field generator 2. In addition, an irradiation device 12, an optical system 43, and a light receiving device 13 are separately installed and fixed.

[0068] The above manufacturing method allows the magnetic resonance component 1, the high-frequency magnetic field generator 2, and the magnet 3, and the magnetic flux direction of the flux transformer 4 to be adjusted in stages, making it easy to arrange them relative to one another and eliminating the need for complicated adjustments after assembly.

[0069] Embodiment 2

[0070] 7 is a cross-sectional view showing an example of a light-guiding member and a magnetic resonance member in a magnetic field measurement device according to embodiment 2. In embodiment 2, a light-guiding member 61 and a light-guiding member 62 are provided instead of the light-guiding member 41 and the light-guiding member 42, and only one or both (here, both) of the light-guiding member 61 and the light-guiding member 62 are provided with recesses 61a, 62a corresponding to the shape of the magnetic resonance member 1 on their end faces. Then, the magnetic resonance member 1 is disposed in the recesses 61a, 62a.

[0071] Specifically, the magnetic resonance member 1 is placed in these recesses 61a, 62a, and the portion of the end face of the light-guiding member 61 other than the recess 61a and the portion of the end face of the light-guiding member 62 other than the recess 62a are in surface contact with each other or surface-joined (for example, with an adhesive) and fixed to each other.

[0072] Other configurations and operations of the magnetic field measuring device according to the second embodiment are similar to those of the first embodiment, and therefore description thereof will be omitted.

[0073] It should be noted that various changes and modifications to the above-described embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing its intended advantages. In other words, such changes and modifications are intended to be included within the scope of the claims.

[0074] For example, in the above embodiment, the magnet 3 may be an electromagnet.

[0075] Furthermore, in the above embodiment, a reflective film (such as a dielectric multilayer film) may be provided on the side surfaces of the light guide members 41 and 42. Also, a reflective film (such as a dielectric multilayer film) may be provided on the side surfaces of the CPCs 43a and 43b.

[0076] Furthermore, in the above embodiment, the light guide members 41 and 42 may have the same length, and the total length of the light guide members 41 and 42 and the magnetic resonance member 1 may be the same as the length of the through hole 4b2 of the bobbin 4b1.

[0077] Furthermore, in the above embodiment, an optical member such as a film that transmits light of the wavelength of the incident light (e.g., 533 nm) and reflects light of the wavelength of the fluorescence (e.g., 600 nm) may be arranged on the end surface 41a (incident side end surface) of the light-guiding member 41. In this case, the fluorescence traveling from the magnetic resonance member 1 to the light-guiding member 41 is reflected by the optical member, travels through the light-guiding members 41 and 42, and is received by the light-receiving device 13. [Industrial Applicability]

[0078] The present invention is applicable to, for example, a magnetic field measuring device and a magnetic field measuring method. [Explanation of symbols]

[0079] 1 Magnetic resonance components 2. High frequency magnetic field generator 2a Coil section 2c,2d opening 3. Magnets 4 Flux Transformers 4a Primary coil 4b Secondary coil 4b1 Bobbin 4b2 Through hole 10 Magnetic sensor section 11 High frequency power supply 12 Irradiation device 13 Light receiving device 41, 61 Light guide member (example of first light guide member) 42, 62 Light guide member (example of second light guide member) 61a, 62a Recess

Claims

1. A magnetic resonance component capable of quantum manipulation of electron spins using microwaves; a high frequency magnetic field generator for applying the microwave to the magnetic resonance member; a magnet for applying a static magnetic field to the magnetic resonance member; an irradiation device for irradiating the magnetic resonance member with incident light of a specific wavelength; a flux transformer that senses a magnetic field to be measured by a primary coil and applies an applied magnetic field corresponding to the sensed magnetic field to the magnetic resonance member by a secondary coil; A columnar first light guiding member that guides the incident light to the magnetic resonance member; a columnar second light guiding member that guides the fluorescence emitted by the magnetic resonance member from the magnetic resonance member; the magnetic resonance member is disposed in a hollow portion of the secondary coil of the flux transformer and in a hollow portion of the magnet, the magnetic resonance member being sandwiched between an end surface of the first light-guiding member and an end surface of the second light-guiding member; A magnetic field measuring device comprising:

2. Further comprising a bobbin for the secondary coil, The bobbin has a through hole, the bobbin supports the first light guiding member and the second light guiding member inserted into the through hole; 2. The magnetic field measuring device according to claim 1,

3. The magnet is a ring magnet, The secondary coil is wound in a ring shape, The central axis of the magnet and the central axis of the secondary coil are aligned with each other, the magnetic resonance member, the first light guiding member, and the second light guiding member are disposed on the central axis; 2. The magnetic field measuring device according to claim 1,

4. one or both of the first light guiding member and the second light guiding member includes a recess corresponding to a shape of the magnetic resonance member; the magnetic resonance member is disposed in the recess; 2. The magnetic field measuring device according to claim 1,

5. a light receiving device that receives the fluorescent light; an optical system from the second light guiding member to the light receiving device, the optical system prevents the incident light from entering the light receiving device; 2. The magnetic field measuring device according to claim 1,

6. 4. The magnetic field measuring device according to claim 3, wherein the magnetic resonance member is disposed at the center of the width of the ring magnet in the direction of the central axis.

7. The high-frequency magnetic field generator includes a substantially circular coil portion that emits microwaves, the secondary coil of the flux transformer is disposed in a hollow portion of the coil portion of the high frequency magnetic field generator; 7. The magnetic field measuring device according to claim 1, further comprising:

8. the magnetic resonance member includes a plurality of color centers capable of quantum manipulation of electron spins by the microwaves; The magnet applies a substantially uniform static magnetic field to the magnetic resonance member; 8. The magnetic field measuring device according to claim 1, further comprising:

9. (a) sensing a magnetic field to be measured with a primary coil of a flux transformer; (b) applying an applied magnetic field corresponding to the sensed magnetic field to a magnetic resonance member capable of electron spin quantum manipulation with microwaves, with a secondary coil of the flux transformer; applying the microwaves to the magnetic resonance member; applying a static magnetic field to the magnetic resonance member; A columnar first light guiding member guides incident light of a specific wavelength from an irradiation device to the magnetic resonance member; A columnar second light guiding member guides the fluorescence emitted by the magnetic resonance member from the magnetic resonance member; the magnetic resonance member is disposed between an end surface of the first light-guiding member and an end surface of the second light-guiding member in a hollow portion of the secondary coil of the flux transformer and in a hollow portion of a magnet that applies the static magnetic field to the magnetic resonance member; A magnetic field measuring method comprising:

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