Magnetic sensor head and magnetic sensor device

Abstract

This invention provides a magnetic sensor head capable of detecting magnetic fields in multiple regions arranged at minute intervals. [Solution] The magnetic sensor head 1 includes a housing having an incident section into which a first light having a first wavelength can be incident, a plurality of magnetic sensor elements having a magnetic resonance frequency whose frequency changes according to the applied magnetic field, and which emit a second light having a second wavelength longer than the first wavelength and whose intensity changes near the magnetic resonance frequency when the first light is incident, a bias magnetic field application element that applies different bias magnetic fields to each of the plurality of magnetic sensor elements, a current path that applies a magnetic field to each of the plurality of magnetic sensor elements according to the supplied current when a current is supplied, and a photoelectric conversion element that is incident on the second light and outputs a detection signal according to the intensity of the incident second light, wherein the current path has different periods and is supplied with a current that is frequency modulated at a frequency near the magnetic resonance frequency of each of the plurality of magnetic sensor elements.

Description

[Technical Field]

[0001] The present invention relates to a magnetic sensor head and a magnetic sensor device. [Background technology]

[0002] A technique is known for using diamond containing NV centers, a type of crystal defect, as a magnetic sensor element (see, for example, Non-Patent Document 1). When an NV center is incident on a green excitation light with a wavelength of 532 nm, it transitions from the ground state ms=0 to the excited state, and when it relaxes back to the ground state, it emits red fluorescence with a wavelength of 600 nm to 800 nm. On the other hand, when an NV center transitions to the excited state in response to excitation light while in the ground state ms=±1 state due to electron spin resonance (ESR), a portion of the ground state relaxation becomes non-radiative relaxation due to intersystem crossing. The intensity of the fluorescence emitted by relaxation when transitioning from the ground state ms=±1 to the excited state is smaller than that of the relaxation when transitioning from the ground state ms=0 to the excited state because a portion of the relaxation becomes non-radiative relaxation. When a diamond transitions from the ground state (ms=±1) to the excited state, the intensity of the fluorescence emitted is lower than when it transitions from the ground state (ms=0) to the excited state. Therefore, the magnetic resonance frequency, which is the frequency at which ESR occurs, can be detected by the change in the intensity of the emitted fluorescence. When the magnetic field applied to the NV center is zero, the magnetic resonance frequency is 2.87 GHz. When a magnetic field is applied to the NV center, the magnetic resonance frequency changes linearly according to the magnitude of the applied magnetic field due to the Zeeman effect. A magnetic sensor device that uses a diamond with an NV center as a magnetic sensor element can detect the magnitude of the magnetic field applied to the NV center by detecting the magnetic resonance frequency.

[0003] Non-Patent Document 2 describes a magnetic sensor head that uses diamond having an NV center as a magnetic sensor element. The magnetic sensor head described in Non-Patent Document 2 guides the fluorescence radiated from the NV center to a photoelectric conversion element by a hemispherical lens and a reflector disposed on the inner wall of the housing, so that the intensity of the fluorescence radiated from the NV center can be detected with high sensitivity.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] Furthermore, there is a need to detect magnetic fields in multiple regions arranged at minute intervals. A magnetic sensor device having a magnetic sensor head formed by arranging multiple magnetic sensor heads as described in Non-Patent Literature 2 can detect magnetic fields in multiple regions spaced approximately 10 mm apart. However, there is a need for a magnetic sensor head capable of detecting magnetic fields in multiple regions arranged at minute intervals, such as when detecting magnetic fields generated by the movement of the human brain.

[0006] The present invention aims to solve these problems and provides a magnetic sensor head capable of detecting magnetic fields in multiple regions arranged at minute intervals. [Means for solving the problem]

[0007] The magnetic sensor head according to the present invention comprises a housing having an incident section into which a first light having a first wavelength can be incident; a plurality of magnetic sensor elements disposed inside the housing, each having a magnetic resonance frequency whose frequency changes according to the applied magnetic field, and which emit a second light having a second wavelength longer than the first wavelength and whose intensity changes near the magnetic resonance frequency when the first light is incident; a bias magnetic field application element that applies different bias magnetic fields to each of the plurality of magnetic sensor elements; a current path that applies a magnetic field to each of the plurality of magnetic sensor elements according to the supplied current when a current is supplied; and a photoelectric conversion element that receives the second light and outputs a detection signal according to the intensity of the incident second light, wherein the current path has different periods and is supplied with a current that is frequency-modulated at a frequency near the magnetic resonance frequency of each of the plurality of magnetic sensor elements.

[0008] Furthermore, in the magnetic sensor head according to the present invention, the bias magnetic field application element is preferably a coil arranged near each of the multiple magnetic sensor elements.

[0009] Furthermore, in the magnetic sensor head according to the present invention, it is preferable that some of the multiple magnetic sensor elements are arranged facing one side of the current path, and the remaining multiple magnetic sensor elements are arranged facing the other side of the current path.

[0010] Furthermore, in the magnetic sensor head according to the present invention, it is preferable that the plurality of magnetic sensor elements are arranged so that a single first light can be incident on them.

[0011] Furthermore, in the magnetic sensor head according to the present invention, it is preferable that the multiple magnetic sensor elements are arranged in a straight line with the incident portion.

[0012] Furthermore, it is preferable that the magnetic sensor head according to the present invention further includes an optical element that reflects the first light that has passed through any of the plurality of magnetic sensor elements and emits it to the other magnetic sensor elements that have not passed through the first light.

[0013] Furthermore, in the magnetic sensor head according to the present invention, it is preferable that the plurality of magnetic sensor elements are arranged in an array, and the current path has a plurality of straight sections extending along the arrangement direction of the plurality of magnetic sensor elements, and connecting sections connecting the plurality of straight sections.

[0014] Furthermore, in the magnetic sensor head according to the present invention, it is preferable that each of the multiple magnetic sensor elements has multiple NV centers.

[0015] Furthermore, in the magnetic sensor head according to the present invention, it is preferable that the plurality of NV centers are formed so that the arrangement direction of nitrogen and vacancies is the same.

[0016] Furthermore, in the magnetic sensor head according to the present invention, it is preferable that the arrangement direction of each of the multiple magnetic sensor elements coincides with the incident direction in which the first light incidents on each of the multiple magnetic sensors.

[0017] Furthermore, in the magnetic sensor head according to the present invention, it is preferable that the full width at half maximum of the magnetic resonance lines of the NV center is narrower than 1 / 4 of the NV center ultrafine structure splitting width, and the difference in the magnetic resonance frequencies of the multiple magnetic sensor elements is at least 4 times the full width at half maximum.

[0018] Furthermore, in the magnetic sensor head according to the present invention, it is preferable that the full width at half maximum of the magnetic resonance lines of the NV center is wider than 1 / 4 of the NV center ultrafine structure splitting width, and the difference in the magnetic resonance frequencies of the multiple magnetic sensor elements is at least 10 MHz.

[0019] Furthermore, it is preferable that the magnetic sensor head according to the present invention further includes a reference bias magnetic field applying element that applies a predetermined reference bias magnetic field to a plurality of magnetic sensor elements.

[0020] Furthermore, the magnetic sensor device according to the present invention includes a housing having an incident section into which a first light having a first wavelength can be incident; a plurality of magnetic sensor elements arranged inside the housing, each having a magnetic resonance frequency whose frequency changes according to the applied magnetic field, and which emit a second light having a second wavelength longer than the first wavelength and whose intensity changes near the magnetic resonance frequency when the first light is incident; a bias magnetic field application element that applies different magnetic fields to each of the plurality of magnetic sensor elements; a current path that applies a magnetic field to each of the plurality of magnetic sensor elements according to the supplied current when a current is supplied; a photoelectric conversion element into which the second light is incident and which outputs a detection signal according to the intensity of the incident second light; a modulation signal generation device that supplies currents to the current path that have different periods and are frequency-modulated at frequencies near the magnetic resonance frequencies of each of the plurality of magnetic sensor elements; and a control device that determines the magnetic field to be applied to each of the plurality of magnetic sensor elements based on the detection signal and outputs the determined magnetic field. [Effects of the Invention]

[0021] The magnetic sensor head according to the present invention can detect magnetic fields in multiple regions arranged at minute intervals. [Brief explanation of the drawing]

[0022] [Figure 1] This is a block diagram of a magnetic sensor device having a magnetic sensor head according to the first embodiment. [Figure 2] Figure 1 is a schematic diagram of the magnetic sensor head. [Figure 3] (a) is a partial side view of the magnetic sensor head shown in Figure 1, and (b) is a partial top view of the magnetic sensor head shown in Figure 1. [Figure 4] Figure 1 is a perspective view of the first magnetic sensor element. [Figure 5] (a) is a diagram showing the distribution of magnetic flux density around the first and second magnetic sensor elements when the first bias current and the second bias current are applied to the first and second coils, respectively, as shown in Figure 1, and (b) is a diagram showing the changes in the first and second magnetic resonance frequencies when the first bias current and the second bias current are applied to the first and second coils, respectively. [Figure 6] This figure shows the relationship between the frequency difference between the first magnetic resonance frequency and the second magnetic resonance frequency and the NV center hyperfine structure splitting width. [Figure 7] This flowchart shows the magnetic detection process performed by the processing unit shown in Figure 1. [Figure 8] This is a partial plan view of a magnetic sensor head according to the first modified example. [Figure 9] This is a partial side view of the magnetic sensor head relating to the second modified example. [Figure 10] This is a partial plan view of a magnetic sensor head relating to the third modified example. [Figure 11] (a) is a partial plan view of the magnetic sensor head according to the fourth modified example, and (b) is a partial plan view of the magnetic sensor head according to the fifth modified example. [Figure 12] This is a partial plan view of a magnetic sensor head relating to the sixth modified example. [Modes for carrying out the invention]

[0023] The magnetic sensor head and magnetic sensor device according to the embodiments will be described below with reference to the attached drawings. However, it should be noted that the technical scope of the present invention is not limited to these embodiments, but extends to the invention described in the claims and its equivalents.

[0024] (Configuration and function of the magnetic sensor device according to the embodiment) Figure 1 is a block diagram of a magnetic sensor device having a magnetic sensor head according to the first embodiment, and Figure 2 is a partial perspective view of the magnetic sensor head shown in Figure 1. Figure 3(a) is a partial side view of the magnetic sensor head shown in Figure 1, and Figure 3(b) is a partial plan view of the magnetic sensor head shown in Figure 1. In Figure 1, electrical signal lines are shown as dashed lines, and optical paths are shown as dashed lines.

[0025] The magnetic sensor device 100 includes a light source 101, an optical system 102, a bias magnetic field application device 103, a modulation signal generation device 104, a control device 110, and a magnetic sensor head 1, and detects the magnetic field around the object to be detected 200. The magnetic sensor head 1 includes a housing 10, a first magnetic sensor element 11, a second magnetic sensor element 12, a first coil 13, a second coil 14, a first hemispherical lens 15, a second hemispherical lens 16, a current path 17, and a photoelectric conversion element 18.

[0026] The light source 101 is a green light-emitting element such as an InGaN semiconductor laser, and outputs a first light L1 having a first wavelength to the optical system 102. In one example, the first wavelength is 532 nm, and in one example, the first light L1 is green light. The first light L1 emitted from the light source 101 is excitation light that excites the NV centers of the first magnetic sensor element 11 and the second magnetic sensor element 12, respectively. The optical system 102 is formed by a plurality of optical elements such as mirrors, lenses, and beam splitters, and separates the first light L1 emitted from the light source 101 and incidents it on the first magnetic sensor element 11 and the second magnetic sensor element 12, respectively.

[0027] The bias magnetic field application device 103 is a current source that supplies current to the first coil 13 and the second coil 14, respectively. The bias magnetic field application device 103 supplies the first bias current I to the first coil 13. B1 In addition to supplying the second coil 14, a second bias current I B2 It supplies the first bias current I B1 or 2 bias current I B2is supplied so as to have the same current value and generate magnetic fields in opposite directions around each of the first coil 13 and the second coil 14. The first bias current I B1 flows clockwise around the first magnetic sensor element 11 when the first coil 13 is viewed in plan view, and the second bias current I B2 flows counterclockwise around the second magnetic sensor element 12 when the second coil 14 is viewed in plan view. Note that the bias magnetic field applying device 103 may further include a reference bias magnetic field applying element that applies a predetermined reference bias magnetic field to both the first coil 13 and the second coil 14.

[0028] The modulation signal generation device 104 generates a frequency-modulated, that is, an FM-modulated FM modulation current, and supplies the generated FM modulation current to the current path 17. The modulation signal generation device 104 is the first magnetic resonance frequency f MR1 which is the magnetic resonance frequency of the first magnetic sensor element 11, and generates a first FM modulation current I M1 that is FM-modulated over a first period P1 at a frequency near. Also, the modulation signal generation device 104 is the second magnetic resonance frequency f MR2 which is the magnetic resonance frequency of the second magnetic sensor element 12, and generates a second FM modulation current I M2 that is FM-modulated over a second period P2 different from the first period P1 at a frequency near. The modulation signal generation device 104 superimposes the generated first FM modulation current I M1 and the second FM modulation current I M2 and supplies them to the current path 17.

[0029] The control device 110 includes a communication unit 111, a storage unit 112, an input unit 113, a display unit 114, and a processing unit 120, and is a portable terminal such as a smartphone that executes part of the detection process, or an electronic computer such as a personal computer and a server.

[0030] The communication unit 111 has a communication interface circuit for connecting the control device 110 to the light source 101, bias magnetic field application device 103, modulation signal generation device 104, and external devices (not shown) via a network (not shown). The communication unit 111 supplies data received from the light source 101, bias magnetic field application device 103, modulation signal generation device 104, and external devices (not shown) via the network to the processing unit 120. The communication unit 111 also transmits data supplied from the processing unit 120 to the light source 101, bias magnetic field application device 103, modulation signal generation device 104, and external devices via the network.

[0031] The storage unit 112 includes, for example, one of a semiconductor memory, a magnetic disk device, and an optical disk device. The storage unit 112 stores operating system programs, driver programs, application programs, data, etc., used for processing in the processing unit 120. For example, the storage unit 112 stores driver programs such as an input device driver program that controls the input unit 113 and an output device driver program that controls the display unit 114. The storage unit 112 stores a magnetic field detection program that causes the processing unit 120 to execute a magnetic field detection process to detect the magnetic field around the magnetic sensor head 1. The storage unit 112 also stores various data and information used for the magnetic field detection process. For example, the storage unit 112 stores a frequency-magnetic field table that shows the relationship between the detected magnetic resonance frequency and the magnetic fields of the first magnetic sensor element 11 and the second magnetic sensor element 12.

[0032] The input unit 113 can be any device that allows operation of the control device 110, such as a keyboard or touchpad. The operator can input characters, numbers, etc., via the input unit 113. When the input unit 113 is operated by the operator, it generates a signal corresponding to that operation. The generated signal is then supplied to the processing unit 120 as an instruction from the operator.

[0033] The display unit 114 can be any device capable of displaying video, images, characters, etc., such as a liquid crystal display or an organic EL (Electro-Luminescence) display. The display unit 114 displays video according to video data supplied from the processing unit 120, images according to image data, characters according to character data, etc. The display unit 114 may also display a graphical user interface (GUI) for operating the control device 110.

[0034] The processing unit 120 has one or more processors and their peripheral circuits. The processing unit 120 comprehensively controls the overall operation of the control device 110, and is, for example, a CPU. The processing unit 120 controls the operation of the communication unit 111, display unit 114, etc., so that various processes of the control device 110 are executed in appropriate procedures according to the programs stored in the storage unit 112, the operation of the input unit 113, etc. The processing unit 120 executes processing based on the programs (operating system programs, driver programs, application programs, etc.) stored in the storage unit 112. In addition, the processing unit 120 can execute multiple programs (application programs, etc.) in parallel.

[0035] The processing unit 120 includes an instruction unit 121, an acquisition unit 122, a determination unit 123, and an output unit 124. Each of these units is a functional module implemented by a program executed on the processor of the processing unit 120. Alternatively, each of these units may be implemented as firmware in the control device 110.

[0036] (Configuration and function of the magnetic sensor head according to the embodiment) The housing 10 contains a base 10a and a reflective material 10b, and houses a first magnetic sensor element 11, a second magnetic sensor element 12, a first coil 13, a second coil 14, a first hemispherical lens 15, and a second hemispherical lens 16. The housing 10 has an incident section 10c formed therein, which is a through-hole from which light is emitted from the optical system 102.

[0037] The base 10a is a flat plate-shaped member made of a non-magnetic material such as diamond, with the first magnetic sensor element 11 and the second magnetic sensor element 12 arranged on one side and the current path 17 arranged on the other side. The reflective material 10b is a cylindrical member made of a non-magnetic material with high light reflectivity such as aluminum, with the first magnetic sensor element 11 and the second magnetic sensor element 12, which are supported by the base 10a, arranged on one end face and the photoelectric conversion element 18 arranged on the other end face.

[0038] The first magnetic sensor element 11 and the second magnetic sensor element 12 are arranged adjacent to each other in the X direction. The distance between the first magnetic sensor element 11 and the second magnetic sensor element 12 is several millimeters to about 10 millimeters. The first magnetic sensor element 11 and the second magnetic sensor element 12 emit a second light L2 in the Z direction in response to a first light L1 incident along the Y direction.

[0039] Figure 4 is a perspective view of the first magnetic sensor element 11.

[0040] The first magnetic sensor element 11 is a single diamond having a rectangular parallelepiped shape and a plurality of NV centers 11a. Each of the plurality of NV centers 11a radiates a second light L2 having a second wavelength as fluorescence when the first light L1 is incident as excitation light from the light source 101 via the optical system 102 and the incident part 10c. The second wavelength is 600 nm to 800 nm, and the second light L2 is red light. In the first magnetic sensor element 11, the plurality of NV centers 11a are formed such that the

[0111] plane orientation, which is the arrangement direction of nitrogen (N) and vacancies (V) in each of the plurality of NV centers 11a, is in the same direction. Each of the plurality of NV centers 11a is arranged such that the arrangement direction of nitrogen (N) and vacancies (V) in each of the plurality of NV centers 11a coincides with the incident direction of the first light L1 incident on the first magnetic sensor element 11 as excitation light. Furthermore, the first magnetic sensor element 11 does not have to be formed such that the

[0111] plane orientation, which is the arrangement direction of nitrogen (N) and vacancies (V) in each of the multiple NV centers 11a, is the same direction. Also, the arrangement direction of nitrogen (N) and vacancies (V) in each of the multiple NV centers 11a of the first magnetic sensor element 11 does not have to be arranged to coincide with the incident direction of the first light L1 incident on the first magnetic sensor element 11 as excitation light.

[0041] The first magnetic sensor element 11 supplies a first bias current I to the first coil 13. B1 When a bias magnetization is applied in response to the supply of a magnetic resonance frequency, the magnetic resonance frequency becomes the first magnetic resonance frequency f MR1 It changes to the first magnetic resonance frequency f. MR1 The amount of change is a quantity corresponding to the sum of the bias magnetic field applied from the first coil 13 and the magnetic field applied from the object to be detected 200.

[0042] The second magnetic sensor element 12 has the same configuration and function as the first magnetic sensor element 11, so a detailed explanation is omitted here. The second magnetic sensor element 12 supplies a second bias current I to the second coil 14. B2 When a bias magnetization is applied in response to the supply of a magnetic field, the magnetic resonance frequency becomes the second magnetic resonance frequency f MR2 It changes to the second magnetic resonance frequency f.MR2 The amount of change is a quantity corresponding to the sum of the bias magnetic field applied from the second coil 14 and the magnetic field applied from the object to be detected 200.

[0043] The first coil 13 is wound around the first magnetic sensor element 11, and receives the first bias current I from the bias magnetic field application device 103. B1 In response to the supply of the first bias current I B1 A bias magnetic field corresponding to the second bias current I is applied to the first magnetic sensor element 11. The second coil 14 is wound around the second magnetic sensor element 12, and the second bias current I is supplied from the bias magnetic field application device 103. B2 In response to the supply of the second bias current I B2 A bias magnetic field corresponding to this is applied to the second magnetic sensor element 12. The first coil 13 and the second coil 14 are bias magnetic field applying elements that apply different bias magnetic fields to the first magnetic sensor element 11 and the second magnetic sensor element 12, respectively.

[0044] Figure 5(a) shows the first bias current I applied to the first coil 13 and the second coil 14, respectively. B1 or 2 bias current I B2 This figure shows the distribution of magnetic flux density around the first magnetic sensor element 11 and the second magnetic sensor element 12 when the first bias current I is applied. Figure 5(b) shows the distribution of magnetic flux density around the first magnetic sensor element 11 and the second magnetic sensor element 12 when the first bias current I is applied to the first coil 13 and the second coil 14, respectively. B1 or 2 bias current I B2 The first magnetic resonance frequency f when applied MR1 and the second magnetic resonance frequency f MR2 This figure shows the changes. In Figure 5(a), the horizontal axis represents the distance in the X direction, and the vertical axis represents the magnitude of the Z component of the magnetic flux density. In Figure 5(b), the horizontal axis represents the frequency, and the vertical axis represents the fluorescence intensity.

[0045] The first coil 13 is supplied with a first bias current I such that, when viewed from above, it flows clockwise around the first magnetic sensor element 11. B1The second coil 14 is supplied with a second bias current I such that, when viewed from above, the second bias current I flows counterclockwise around the second magnetic sensor element 12. B2 The first bias current I is supplied. B1 or 2 bias current I B2 By flowing the magnetic flux in opposite directions, the magnetic flux density at the center P1 of the first magnetic sensor element 11 is made negative, and the magnetic flux density at the center P2 of the second magnetic sensor element 12 is made positive.

[0046] When the magnetic flux density at the center P1 of the first magnetic sensor element 11 becomes negative, the first magnetic resonance frequency f of the first magnetic sensor element 11 is affected. MR1 This shifts to the lower frequency side. On the other hand, as the magnetic flux density at the center P2 of the second magnetic sensor element 12 becomes positive, the second magnetic resonance frequency f of the second magnetic sensor element 12 is shifted. MR2 This shifts to the higher frequency side. The first magnetic resonance frequency f MR1 The frequency shifts to the lower frequency side, and the second magnetic resonance frequency f MR2 As it shifts to the higher frequency side, the first magnetic resonance frequency f MR1 and the second magnetic resonance frequency f MR2 A frequency difference Δf occurs between the two points.

[0047] Figure 6 shows the first magnetic resonance frequency f MR1 and the second magnetic resonance frequency f MR2 This figure shows the relationship between the frequency difference between and NV center hyperstructure splitting width. In Figure 6, the horizontal axis represents frequency, and the vertical axis represents fluorescence intensity. The NV center hyperstructure splitting width is 14 In the case of N, it is 2.2MHz. 15 In the case of N, the frequency is 3.1 MHz.

[0048] First magnetic resonance frequency f MR1 and the second magnetic resonance frequency f MR2The frequency difference Δf between the two is sufficient if the full width at half maximum WH of the magnetic resonance lines of the NV center is at least four times the full width at half maximum WH when the full width at half maximum WH of the magnetic resonance lines of the NV center is narrower than 1 / 4 of the ultrafine structure splitting width W of the NV center. By setting the difference in magnetic flux density applied to each of the first magnetic sensor element 11 and the second magnetic sensor element 12 to 36 μT, the frequency difference Δf can be set to 1 MHz. The difference in magnetic flux density applied to each of the magnetic sensor element 11 and the second magnetic sensor element 12 is determined such that the frequency difference Δf is at least four times the full width at half maximum WH of the magnetic resonance lines of the NV center.

[0049] Also, the first magnetic resonance frequency f MR1 and the second magnetic resonance frequency f MR2 The frequency difference Δf between the two points should be at least 10 MHz when the full width at half maximum WH of the magnetic resonance lines of the NV center is wider than 1 / 4 of the hyperfine structure splitting width W of the NV center.

[0050] The first hemispherical lens 15 is a high refractive index hemispherical lens and is positioned to cover the surface of the first magnetic sensor element 11 facing the photoelectric conversion element 18. The first hemispherical lens 15 guides the second light L2 radiated from the multiple NV centers 11a of the first magnetic sensor element 11 toward the photoelectric conversion element 18. The second hemispherical lens 16 is a high refractive index hemispherical lens, similar to the first hemispherical lens 15, and is positioned to cover the surface of the second magnetic sensor element 12 facing the photoelectric conversion element 18. The second hemispherical lens 16 guides the second light L2 radiated from the multiple NV centers of the second magnetic sensor element 12 toward the photoelectric conversion element 18.

[0051] The current path 17, also called a microwave guide, is a flat plate-shaped member made of a conductive, non-magnetic material such as copper, and the first FM modulation current I generated by the modulation signal generation device 104 M1 and 2FM modulated current I M2 The currents are superimposed and supplied. The current path 17 is supplied with the first FM modulated current I M1 and 2FM modulated current I M2 In response to the supply of the first FM modulation current I, the first magnetic sensor element 11 and the second magnetic sensor element 12 are each supplied with the first FM modulation current IM1 and 2FM modulated current I M2 A magnetic field is applied according to the conditions.

[0052] The photoelectric conversion element 18 is a photodiode, into which the second light L2 emitted from the first magnetic sensor element 11 and the second magnetic sensor element 12 is incident, and a detection signal Ed corresponding to the intensity of the incident second light is output to the control device 110.

[0053] (Magnetic detection process performed by the magnetic sensor device according to the embodiment) Figure 7 is a flowchart showing the magnetic detection process performed by the processing unit 120. The magnetic detection process shown in Figure 7 is mainly performed by the processing unit 120 in cooperation with each element of the magnetic sensor device 100, based on a magnetic detection program that is stored in the storage unit 112 beforehand.

[0054] First, the indicator unit 121 outputs an emission signal to the light source 101 indicating that the first light L1 should be emitted (S101). The light source 101 starts emitting the first light L1 in response to the emission signal. The first light L1 emitted from the light source 101 is input to the first magnetic sensor element 11 and the second magnetic sensor element 12 via the optical system 102. The NV centers of the first magnetic sensor element 11 and the second magnetic sensor element 12 radiate fluorescence as the second light L2 in response to the first light L1 being input as excitation light.

[0055] Next, the indicator unit 121 outputs a bias current signal to the bias magnetic field application device 103 indicating that bias current should be supplied to the first coil 13 and the second coil 14, respectively (S102). In response to the bias current signal being input, the bias magnetic field application device 103 supplies a first bias current I to the first coil 13. B1 The supply of the second bias current I to the second coil 14 is started. B2 The supply of the first bias current I is started to the first coil 13. B1 As the supply of the first magnetic sensor element 11 is adjusted, the magnetic resonance frequency of the first magnetic resonance frequency f MR1It changes to the second bias current I in the second coil 14. B2 As the supply of the second magnetic sensor element 12 is adjusted, the magnetic resonance frequency of the second magnetic resonance frequency f MR2 It changes to.

[0056] Next, the instruction unit 121 outputs a modulation current signal to the modulation signal generator 104 indicating that an FM modulation current should be supplied to the current path 17 (S103). The modulation signal generator 104, in response to the input modulation current signal, generates a first FM modulation current I M1 and 2FM modulated current I M2 Generates the first FM modulated current I M1 and 2FM modulated current I M2 The current is superimposed and supplied to the current path 17.

[0057] Next, the acquisition unit 122 acquires detection information corresponding to the detection signal Ed over a predetermined detection period (S104). The acquisition unit 122 acquires detection information corresponding to the detection signal Ed input from the photoelectric conversion element 18 at a predetermined sampling period and stores the acquired detection information in the storage unit 112.

[0058] Next, the determination unit 123 demodulates the waveforms corresponding to the detection information acquired in the process shown in S104 into a first waveform W1 having a first period P1 and a second waveform W2 having a second period P2 (S105). The determination unit 123 demodulates the waveforms corresponding to the detection information into the first waveform W1 having a first period P1 and the second waveform W2 having a second period P2, respectively, by FM demodulation processing. The determination unit 123 stores the first waveform information representing the first waveform W1 and the second waveform information representing the second waveform W2 in the storage unit 112.

[0059] Next, the determination unit 123 determines the first magnetic resonance frequency f from the first waveform W1 and the second waveform W2 separated by the process shown in S105. MR1 and the second magnetic resonance frequency f MR2 Extract (S106). The determination unit 123 extracts the first magnetic resonance frequency f from the first waveform W1, for example, from the change in amplitude of the first waveform W1 and the second waveform W2. MR1 The extracted first magnetic resonance frequency fMR1 The first frequency information indicating the second magnetic resonance frequency f is stored in the storage unit 112. The determination unit 123 uses a known extraction method to determine the second magnetic resonance frequency f from the second waveform W2. MR2 The extracted second magnetic resonance frequency f MR2 The second frequency information indicating this is stored in the storage unit 112.

[0060] Next, the determination unit 123 determines the magnetic field applied from the object to be detected 200 (S107). The determination unit 123 refers to the frequency magnetic field table stored in the storage unit 112 and determines the first magnetic resonance frequency f extracted in the process shown in S106. MR1 The magnetic field corresponding to this is determined to be the first magnetic field applied from the object to be detected 200 to the first magnetic sensor element 11. The determination unit 123 stores the first magnetic field information indicating the determined first magnetic field in the storage unit 112. The determination unit 123 refers to the frequency magnetic field table stored in the storage unit 112 and extracts the second magnetic resonance frequency f in the process shown in S106. MR2 The magnetic field corresponding to this is determined to be the second magnetic field applied from the object to be detected 200 to the second magnetic sensor element 12. The determination unit 123 stores the second magnetic field information indicating the determined second magnetic field in the storage unit 112.

[0061] The output unit 124 then outputs a magnetic field signal indicating the detected magnetic field to the display unit 114 (S108). The output unit 124 outputs a first magnetic field signal indicating the first magnetic field detected by the first magnetic sensor element 11 to the display unit 114, and outputs a second magnetic field signal indicating the second magnetic field detected by the second magnetic sensor element 12 to the display unit 114. The display unit 114 displays the first magnetic field corresponding to the first magnetic field signal and the second magnetic field corresponding to the second magnetic field signal.

[0062] (Effects of the magnetic sensor head according to this embodiment) The magnetic sensor head 1 can detect the magnetic resonance frequencies of the first magnetic sensor element 11 and the second magnetic sensor element 12 by supplying a current modulated at a frequency near the magnetic resonance frequency of each of the first magnetic sensor element 11 and the second magnetic sensor element 12 to the current path 17. Since the magnetic sensor head 1 can detect the magnetic resonance frequencies of the first magnetic sensor element 11 and the second magnetic sensor element 12 which are located inside the housing 10, the first magnetic sensor element 11 and the second magnetic sensor element 12 can be arranged inside a single housing 10, enabling miniaturization.

[0063] Furthermore, by using the first coil 13 and the second coil 14, which are wound around the first magnetic sensor element 11 and the second magnetic sensor element 12 respectively, as bias magnetic field application elements, a desired magnetic field distribution can be formed easily and inexpensively.

[0064] Furthermore, since each of the first magnetic sensor element 11 and the second magnetic sensor element 12 is formed such that the arrangement direction of the nitrogen and vacancies is the same, it has a single magnetic resonance frequency, making it easy to detect the magnetic resonance frequency.

[0065] Furthermore, since the arrangement of nitrogen and vacancies in each of the first magnetic sensor element 11 and the second magnetic sensor element 12 is aligned with the incident direction in which the first light incidents on each of the multiple magnetic sensor elements, the intensity change of the second light at the magnetic resonance frequency can be greatly increased.

[0066] Furthermore, the magnetic sensor head 1 has a first FM modulation current I M1 and 2FM modulated current I M2 By increasing the modulation frequency, the time resolution can be improved. For example, the magnetic sensor head 1 can achieve a time resolution finer than 1 ms by increasing the modulation frequency to about 10 kHz.

[0067] (Modified example of the magnetic sensor head according to this embodiment) The magnetic sensor head 1 has a first magnetic sensor element 11 and a second magnetic sensor element 12, each of which is a single diamond. However, the magnetic sensor head according to this embodiment may have a plurality of magnetic sensor elements formed from a single diamond.

[0068] Figure 8 is a partial plan view of a magnetic sensor head according to the first modified example. Figure 8 corresponds to the partial plan view of the magnetic sensor head 1 shown in Figure 3(b). The magnetic sensor head 2 can be placed in the magnetic sensor device 100 in the same way as the magnetic sensor head 1.

[0069] Magnetic sensor head 2 differs from magnetic sensor head 1 in that it has a first magnetic sensor element 21 and a second magnetic sensor element 22 instead of the first magnetic sensor element 11 and the second magnetic sensor element 12. The configuration and function of the components of magnetic sensor head 2 other than the first magnetic sensor element 21 and the second magnetic sensor element 22 are the same as those of magnetic sensor head 1, so a detailed explanation is omitted here.

[0070] The first magnetic sensor element 21 and the second magnetic sensor element 22 differ from the first magnetic sensor element 11 and the second magnetic sensor element 12 in that they are formed on a single diamond 20. The first magnetic sensor element 21 is arranged to include a plurality of first NV centers 21a, and the second magnetic sensor element 22 is arranged to include a plurality of second NV centers 22a.

[0071] Since the magnetic sensor head 2 has the first magnetic sensor element 21 and the second magnetic sensor element 22 formed on a single diamond 20, it can be made smaller than the magnetic sensor head 1 which has the first magnetic sensor element 11 and the second magnetic sensor element 12 formed on separate diamonds.

[0072] Furthermore, in the magnetic sensor head 1, the first magnetic sensor element 11 and the second magnetic sensor element 12 are arranged on one side of the current path 17. However, in the magnetic sensor head according to this embodiment, the first magnetic sensor element 11 may be arranged on one side of the current path 17, and the second magnetic sensor element 12 may be arranged on the other side of the current path 17.

[0073] Figure 9 is a partial side view of a magnetic sensor head according to a second modified example. The magnetic sensor head 3 can be placed in the magnetic sensor device 100, similar to the magnetic sensor head 1.

[0074] The magnetic sensor head 3 differs from the magnetic sensor head 1 in the arrangement of the first magnetic sensor element 11 and the second magnetic sensor element 12. The configuration and function of the components of the magnetic sensor head 3, other than the arrangement of the first magnetic sensor element 11 and the second magnetic sensor element 12, are the same as those of the components of the magnetic sensor head 1, so a detailed explanation is omitted here. The first magnetic sensor element 11 and the second magnetic sensor element 12 are arranged so as to straddle the current path 17.

[0075] The magnetic sensor head 3 can simultaneously measure the magnetic fields of two objects placed on opposite sides of the current path 17 by arranging the first magnetic sensor element 11 and the second magnetic sensor element 12 so as to straddle the current path 17.

[0076] Furthermore, when the magnetic sensor head has three or more magnetic sensor elements, some of the multiple magnetic sensor elements are arranged facing one side of the current path, and the remaining multiple magnetic sensor elements are arranged facing the other side of the current path.

[0077] Furthermore, in the magnetic sensor head 1, the first magnetic sensor element 11 and the second magnetic sensor element 12 are subjected to a bias magnetic field by the first coil 13 and the second coil 14. However, in the magnetic sensor head according to this embodiment, the first magnetic sensor element 11 and the second magnetic sensor element 12 may also be subjected to a bias magnetic field by a magnetic field application element other than the first coil 13 and the second coil 14.

[0078] Figure 10 is a partial plan view of a magnetic sensor head according to a third modified example. The magnetic sensor head 5 can be placed in the magnetic sensor device 100, similar to the magnetic sensor head 1.

[0079] The magnetic sensor head 4 differs from the magnetic sensor head 2 in that it has a first magnetic field gradient coil 23 and a second magnetic field gradient coil 24 instead of the first magnetic sensor element 11 and the second magnetic sensor element 12. The configuration and function of the components of the magnetic sensor head 4 other than the first magnetic field gradient coil 23 and the second magnetic field gradient coil 24 are the same as those of the components of the magnetic sensor head 2, so a detailed explanation is omitted here.

[0080] The first magnetic field gradient coil 23 and the second magnetic field gradient coil 24 apply a bias magnetic field to the first magnetic sensor element 11 and the second magnetic sensor element 12, similar to the first coil 13 and the second coil 14. The first bias current I supplied to the first magnetic field gradient coil 23 B1 The second bias current I supplied to the second magnetic field gradient coil 24 and the second magnetic field gradient coil 24 B2 These are supplied with the same current value and to generate magnetic fields in opposite directions around the first coil 13 and the second coil 14, respectively. The configuration of the first magnetic field gradient coil 23 and the second magnetic field gradient coil 24 is described in Non-Patent Literature 3, so a detailed explanation is omitted here.

[0081] Since the magnetic sensor head 4 does not require the process of winding the first coil 13 and the second coil 14 around the first magnetic sensor element 11 and the second magnetic sensor element 12, the manufacturing process is simpler than that of the magnetic sensor head 1, and manufacturing costs can be reduced.

[0082] Furthermore, in the magnetic sensor head 1, the first magnetic sensor element 11 and the second magnetic sensor element 12 are arranged so that separate first light L1, which is delimited by the optical system 102, is incident on them. However, in the magnetic sensor head according to this embodiment, the first magnetic sensor element 11 and the second magnetic sensor element 12 may be arranged so that a single first light L1 is incident on them.

[0083] Figure 11(a) is a partial plan view of the magnetic sensor head according to the fourth modified example, and Figure 11(b) is a partial plan view of the magnetic sensor head according to the fifth modified example. The magnetic sensor heads 5 and 6 can be arranged in the magnetic sensor device 100 in the same way as the magnetic sensor head 1.

[0084] The magnetic sensor head 5 differs from the magnetic sensor head 1 in the direction in which the first light L1 is incident on the first magnetic sensor element 11 and the second magnetic sensor element 12. The configuration and function of the components of the magnetic sensor head 5, other than the direction in which the first light L1 is incident on the first magnetic sensor element 11 and the second magnetic sensor element 12, are the same as those of the components of the magnetic sensor head 1, so a detailed explanation is omitted here.

[0085] In the magnetic sensor head 5, the first magnetic sensor element 11 and the second magnetic sensor element 12 are arranged in a straight line with the incident portion 10c of the housing 10. By arranging the first magnetic sensor element 11 and the second magnetic sensor element 12 in a straight line with the incident portion 10c of the housing 10, a single first light L1 can be incident on them.

[0086] The magnetic sensor head 6 differs from the magnetic sensor head 2 in that it has an optical element 25. The configuration and function of the components of the magnetic sensor head 6 other than the optical element 25 are the same as those of the components of the magnetic sensor head 2, so a detailed explanation is omitted here.

[0087] The optical element 25 has multiple mirrors or prisms and is arranged so that the first light emitted from the first magnetic sensor element 11 is incident on the second magnetic sensor element 12. The first magnetic sensor element 11 and the second magnetic sensor element 12 are arranged so that the optical element 25 is incident on the second magnetic sensor element 12 so that the first light emitted from the first magnetic sensor element 11 is incident on the second magnetic sensor element 12, thereby enabling a single first light L1 to be incident on them.

[0088] Since the magnetic sensor heads 5 and 6 have multiple magnetic sensor elements arranged so that a single first light L1 is incident on them, the optical system design is simpler than that of the magnetic sensor head 1, and manufacturing costs can be reduced.

[0089] Furthermore, while the magnetic sensor head 1 has two magnetic sensor elements, a first magnetic sensor element 11 and a second magnetic sensor element 12, the magnetic sensor head according to this embodiment may have three or more magnetic sensor elements.

[0090] Figure 12 is a partial plan view of a magnetic sensor head according to the sixth modified example. The magnetic sensor head 7 can be placed in the magnetic sensor device 100, similar to the magnetic sensor head 1.

[0091] The magnetic sensor head 7 differs from the magnetic sensor head 1 in that it has a third magnetic sensor element 31, a fourth magnetic sensor element 32, and a third coil 33 and a fourth coil 34. It also differs from the magnetic sensor head 1 in that it has a current path 37 instead of a current path 17. The configuration and function of the components of the magnetic sensor head 7 other than the third magnetic sensor element 31 to the fourth coil 34 and the current path 37 are the same as those of the components of the magnetic sensor head 1, so a detailed explanation is omitted here.

[0092] The third magnetic sensor element 31 and the fourth magnetic sensor element 32 are single diamonds having multiple NV centers 11a, similar to the first magnetic sensor element 11 and the second magnetic sensor element 12. The third magnetic sensor element 31 is positioned adjacent to the first magnetic sensor element 11, and receives first light L1 that has passed through the first magnetic sensor element 11, outputting second light L2 to a photoelectric conversion element via a hemispherical lens (not shown). The fourth magnetic sensor element 32 is positioned adjacent to the second magnetic sensor element 12, and receives first light L1 that has passed through the second magnetic sensor element 12, outputting second light L2 to a photoelectric conversion element via a hemispherical lens (not shown). The first magnetic sensor element 11 and the second magnetic sensor element 12, as well as the third magnetic sensor element 31 and the fourth magnetic sensor element 32, are arranged in an array.

[0093] The third coil 33 is wound around the third magnetic sensor element 31 and applies a bias magnetic field to the third magnetic sensor element 31 corresponding to the third bias current supplied from the bias magnetic field application device 103. The fourth coil 34 is wound around the fourth magnetic sensor element 32 and applies a bias magnetic field to the fourth magnetic sensor element 32 corresponding to the fourth bias current supplied from the bias magnetic field application device 103.

[0094] The current path 37, like the current path 17, is a flat plate-shaped member made of a conductive non-magnetic material such as copper, and has a pair of parallel-extending straight sections 38a and 38b and a connecting section 39. The straight section 38a has the first magnetic sensor element 11 and the third magnetic sensor element 31 arranged on it and extends along the alignment direction of the first magnetic sensor element 11 and the third magnetic sensor element 31. The straight section 38b has the second magnetic sensor element 12 and the fourth magnetic sensor element 32 arranged on it and extends along the alignment direction of the second magnetic sensor element 12 and the fourth magnetic sensor element 32. The connecting section 39 extends in a direction perpendicular to the extension direction of the pair of straight sections 38a and 38b so as to connect the pair of straight sections 38a and 38b.

[0095] Since the magnetic sensor head 7 has a first magnetic sensor element 11 and a second magnetic sensor element 12, as well as a third magnetic sensor element 31 and a fourth magnetic sensor element 32 arranged in an array, it can detect the magnetic field distribution in two dimensions.

[0096] Furthermore, each of the pair of linear sections 38a and 38b may have three or more magnetic sensor elements. Also, the magnetic sensor head may have three or more linear sections. When the sensor head has three or more linear sections, the linear sections are connected by connecting sections. [Explanation of Symbols]

[0097] 1-7 Magnetic sensor heads 10 cabinets 11. First magnetic sensor element 12 Second magnetic sensor element 13. First coil (bias magnetic field application element) 14. Second coil (bias magnetic field application element) 15. First hemispheric lens 16. Second hemispheric lens 17 Current path 18 Photoelectric conversion element 100 Magnetic sensor device.

Claims

1. A housing having an incident portion into which a first light having a first wavelength can be incident, A plurality of magnetic sensor elements are arranged inside the housing and have a magnetic resonance frequency whose frequency changes in response to an applied magnetic field, and emit a second light having a second wavelength longer than the first wavelength and whose intensity changes near the magnetic resonance frequency when the first light is incident on it. A bias magnetic field applying element that applies a different bias magnetic field to each of multiple magnetic sensor elements, A current path applies a magnetic field to each of the plurality of magnetic sensor elements in response to the supply of current, The photoelectric conversion element includes a second light that is incident on it and outputs a detection signal corresponding to the intensity of the incident second light, The current path has different periods, and is supplied with a frequency-modulated current at a frequency near the magnetic resonance frequency of each of the plurality of magnetic sensor elements. A magnetic sensor head characterized by the following features.

2. The magnetic sensor head according to claim 1, wherein the bias magnetic field application element is a coil arranged near each of the plurality of magnetic sensor elements.

3. The magnetic sensor head according to claim 1, wherein some of the plurality of magnetic sensor elements are arranged facing one side of the current path, and the remaining plurality of magnetic sensor elements are arranged facing the other side of the current path.

4. The magnetic sensor head according to claim 1, wherein the plurality of magnetic sensor elements are arranged so that a single first light can be incident on them.

5. The magnetic sensor head according to claim 4, wherein the plurality of magnetic sensor elements are arranged in a straight line with the incident portion.

6. The magnetic sensor head according to claim 4, further comprising an optical element that reflects the first light that has passed through any of the plurality of magnetic sensor elements and emits it to another magnetic sensor element that has not passed through the first light.

7. The plurality of magnetic sensor elements are arranged in an array, The magnetic sensor head according to claim 1, wherein the current path has a plurality of straight sections extending along the arrangement direction of the plurality of magnetic sensor elements, and a connecting section connecting the plurality of straight sections.

8. A magnetic sensor head according to any one of claims 1 to 7, wherein each of the plurality of magnetic sensor elements has a plurality of NV centers.

9. The magnetic sensor head according to claim 8, wherein the plurality of magnetic sensor elements are formed in a single diamond.

10. The magnetic sensor head according to claim 8, wherein the plurality of NV centers are formed such that the arrangement direction of nitrogen and pores is the same direction.

11. The magnetic sensor head according to claim 10, wherein each of the plurality of magnetic sensor elements is arranged such that its arrangement direction coincides with the incident direction in which the first light is incident on each of the plurality of magnetic sensor elements.

12. The full width at half maximum of the magnetic resonance lines of the NV center is narrower than 1 / 4 of the ultrafine structure splitting width of the NV center. The magnetic sensor head according to claim 8, wherein the difference in the magnetic resonance frequencies of each of the plurality of magnetic sensor elements is at least four times the full width at half maximum.

13. The full width at half maximum of the magnetic resonance lines of the NV center is wider than 1 / 4 of the hyperfine structure splitting width of the NV center. The magnetic sensor head according to claim 8, wherein the difference in the magnetic resonance frequencies of each of the plurality of magnetic sensor elements is at least 10 MHz or more.

14. The magnetic sensor head according to claim 1, further comprising a reference bias magnetic field applying element for applying a predetermined reference bias magnetic field to the plurality of magnetic sensor elements.

15. A housing having an incident portion into which a first light having a first wavelength can be incident, A plurality of magnetic sensor elements are arranged inside the housing and have a magnetic resonance frequency whose frequency changes in response to an applied magnetic field, and emit a second light having a second wavelength longer than the first wavelength and whose intensity changes near the magnetic resonance frequency when the first light is incident on it. A bias magnetic field applying element that applies a different bias magnetic field to each of multiple magnetic sensor elements, A current path applies a magnetic field to each of the plurality of magnetic sensor elements in response to the supply of current, A magnetic sensor head having a photoelectric conversion element that receives the second light and outputs a detection signal corresponding to the intensity of the incident second light, A modulation signal generating device that supplies currents to the current path that have different periods and are frequency-modulated at frequencies near the magnetic resonance frequencies of each of the plurality of magnetic sensor elements, A control device that determines the magnetic field applied to each of the plurality of magnetic sensor elements based on the detection signal and outputs the determined magnetic field, A magnetic sensor device characterized by having [a certain feature].

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