Diamond magnetic sensor unit and diamond magnetic sensor system

Abstract

This diamond magnetic sensor unit comprises: a sensor unit including diamond having a color center with electron spin; an excitation light irradiation unit for irradiating the diamond with excitation light; and a detection unit for detecting emitted light from the color center of the diamond. The detection unit detects emitted light generated as a result of the diamond being irradiated with excitation light by the excitation light irradiation unit without being irradiated with electromagnetic waves. The detection unit is at least 10 mm spaced apart from the sensor unit and may include a conductive member for transmitting electromagnetic waves.

Description

[Technical Field]

[0001] This disclosure relates to a diamond magnetic sensor unit and a diamond magnetic sensor system. This application claims priority to Japanese Patent Application No. 2021-010936, filed on January 27, 2021, and incorporates by reference all of the contents of said Japanese application. [Background technology]

[0002] A sensor using the NV center of diamond is known. When the NV center of diamond is used in combination with a microscope, it is configured as shown in FIG. 1, for example. That is, an LED 900 arranged on a substrate 912 emits green light to excite the NV center of a diamond 904. The emitted light passes through a short pass filter (SPF) 902 and then enters the diamond 904 arranged on the substrate 914. This allows the NV center to be detected. - The electron at the center is excited. When the excited electron returns to its original ground state, red fluorescence is emitted from the diamond 904. The fluorescence is collected by the lens 906, passes through an LPF (Long Pass Filter) 908, and is then detected by a photodiode 910 disposed on a substrate 916. Microwaves generated by an external device (not shown) are also irradiated onto the diamond 904. As a result, when the diamond 904 is excited into a state of resonance with a different spin state, the intensity of the red fluorescence from the diamond 904 changes. This change is detected by the photodiode 910. The lens 906 can be configured as a high-performance optical microscope lens, or a simple lens.

[0003] Patent Document 1 below discloses a scanning probe microscope (i.e., a frequency modulation atomic force microscope (FM-AFM)) that uses the NV center of diamond. Also, Patent Document 2 below discloses a magnetic field detection device that uses the NV center of diamond.

[0004] Non-Patent Document 1 below discloses an experimental device that irradiates a diamond containing an NV center with excitation light and detects photoluminescence (hereinafter referred to as PL) emitted from the NV center without irradiating it with microwaves. This experimental device is equipped with an electromagnet for applying a sweeping magnetic field and a perturbation magnetic field of a predetermined frequency to the diamond. When the diamond is irradiated with excitation light and PL is detected while the sweeping magnetic field and perturbation magnetic field are applied to the diamond, the intensity of the PL changes depending on the external magnetic field received by the NV center. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-67650 A [Patent Document 2] Japanese Patent Application Publication No. 2018-136316 [Non-patent literature]

[0006] [Non-Patent Document 1] Arne Wickenbrock, et al., “Microwave-free magnetometry with nitrogen-vacancy centers in diamond,” Applied Physics Letters 109, 053505 (2016) [Non-patent document 2] JP. Tetienne, L. Rondin, P. Spinicelli, M. Chipaux, T. Debuisschert, JF. Roch, and V. Jacques, “Magnetic-field-dependent photodynamics of single NV defects in diamond: an application to qualitative all-optical magnetic imaging,” New J. Phys. 14, 103033 (2012) [Non-patent document 3] LT Hall, P. Kehayias, DA Simpson, A. Jarmola, A. Stacey, D. Budker, and LCL Hollenberg, “Detection of nanoscale electron spin resonance spectra demonstrated using nitrogen-vacancy center probes in diamond,” Nat. Commun. 7, 10211 (2016) Summary of the Invention

[0007] A diamond magnetic sensor unit according to one aspect of the present disclosure includes a sensor section including a diamond having a color center with electronic spin, an excitation light irradiation section that irradiates the diamond with excitation light, and a detection section that detects radiation light from the color center of the diamond, wherein the detection section detects radiation light generated when excitation light is irradiated onto the diamond by the excitation light irradiation section without irradiating electromagnetic waves onto the diamond, and may include a conductive member that is positioned 10 mm or more away from the sensor section and transmits electromagnetic waves.

[0008] A diamond magnetic sensor system according to another aspect of the present disclosure includes the above-mentioned diamond magnetic sensor unit, an application unit, and a control unit that controls the excitation light irradiation unit, detection unit, and application unit, and the control unit applies to the diamond, together with the excitation light, a temporal combination of alternating magnetic, magnetic field, potential, and electric field patterns by the application unit. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing a conventional microscope using a diamond NV center. [Figure 2] FIG. 2 is a schematic diagram showing a schematic configuration of the diamond magnetic sensor unit according to the first embodiment of the present disclosure. [Figure 3A]FIG. 3A is a diagram showing the energy levels of an NV center and their transitions in the absence of an external magnetic field. [Figure 3B] FIG. 3B is a diagram showing the energy levels of the NV center and their transitions in the presence of an external magnetic field. [Figure 4] FIG. 4 is a schematic diagram showing a schematic configuration of a diamond magnetic sensor unit according to the second embodiment of the present disclosure. [Figure 5] FIG. 5 is a schematic diagram showing a schematic configuration of a diamond magnetic sensor unit according to a first modified example. [Figure 6] FIG. 6 is a schematic diagram showing a schematic configuration of a diamond magnetic sensor unit according to the second modified example. [Figure 7] FIG. 7 is a schematic diagram showing a schematic configuration of a diamond magnetic sensor unit according to a third modified example. [Figure 8] FIG. 8 is a schematic diagram showing a schematic configuration of a diamond magnetic sensor unit according to the fourth modified example. [Figure 9] FIG. 9 is a perspective view showing an example of the second embodiment (see FIG. 4). DETAILED DESCRIPTION OF THE INVENTION

[0010] [Problem to be solved by the invention] In the devices disclosed in Patent Documents 1 and 2, it is necessary to irradiate a diamond containing an NV center with microwaves. This requires a microwave generator, a microwave irradiation coil, and a mechanism for transmitting microwaves to the microwave irradiation coil located near the diamond, which results in a problem of high costs.

[0011] When using a sensor with high-voltage equipment such as electric power equipment, partial discharges and other events can cause instantaneous high voltages and large currents, which can also generate powerful electromagnetic waves. If a conductive member such as a coil for irradiating microwaves is present near the diamond, eddy currents will be generated, affecting the sensor's detection accuracy. Therefore, it is preferable that no conductive member be present near the diamond. Furthermore, discharges can damage the light-emitting element and light-receiving element.

[0012] The experimental apparatus disclosed in Non-Patent Document 1 focuses the emitted light from the diamond (i.e., the NV center) using a lens, inputs it to a photodiode via a dichroic mirror, and transmits the output signal (i.e., electrical signal) of the photodiode to a detection device via a cable. In this configuration, the detection sensitivity of the emitted light decreases when the photodiode is placed farther away from the diamond, so the photodiode must be placed close to the diamond. Therefore, the configuration disclosed in Non-Patent Document 1 cannot be used for sensors used in high-voltage environments (for example, it is affected by partial discharge, etc.).

[0013] Therefore, an object of the present disclosure is to provide a diamond magnetic sensor unit and a diamond magnetic sensor system that are capable of detecting magnetic fields and the like with high accuracy from a distance without being damaged in a high-voltage environment.

[0014] [Effects of the invention] According to the present disclosure, it is possible to provide a diamond magnetic sensor unit and a diamond magnetic sensor system that are not damaged even in a high-voltage environment and are capable of detecting magnetic fields, electric fields, etc. with high accuracy even from a remote location.

[0015] [Description of the embodiments of the present disclosure] The contents of the embodiments of the present disclosure will be listed and explained below. At least some of the embodiments described below may be combined in any combination.

[0016] (1) A diamond magnetic sensor unit according to a first aspect of the present disclosure includes a sensor section including a diamond having a color center with electronic spin, an excitation light irradiating section that irradiates the diamond with excitation light, and a detection section that detects radiation from the color center of the diamond, and the detection section detects radiation generated when the excitation light irradiating section irradiates the diamond with excitation light without irradiating the diamond with electromagnetic waves, and may include a conductive member that is disposed 10 mm or more away from the sensor section and transmits electromagnetic waves. This allows for accurate detection of magnetic fields without being damaged even in high-voltage environments of 1 kV or more.

[0017] (2) The conductive member can be positioned at a distance of 50 mm or more from the sensor unit, which prevents damage even in high-voltage environments of 5 kV or more and improves detection accuracy.

[0018] (3) The conductive member may be disposed at a distance of 100 mm or more from the sensor unit, which prevents damage even in a high-voltage environment of 10 kV or more and improves detection accuracy.

[0019] (4) The diamond magnetic sensor unit can further include an optical waveguide for transmitting the excitation light and the emitted light, which can prevent the detection unit and other components from being damaged even if a discharge or other event occurs in the high-voltage environment in which the sensor unit is located.

[0020] (5) The sensor part having diamond may be entirely made of an electrically insulating material, which can prevent the sensor part from being damaged even if a discharge or the like occurs in the high-voltage environment in which the sensor part is placed.

[0021] (6) The sensor unit may be installed in an environment where a voltage difference of 200 V or more may occur. This prevents the sensor unit from being damaged even if a discharge or the like occurs in a voltage environment of 200 V or more.

[0022] (7) The sensor unit may be installed in an environment where a voltage difference of 600 V or more may occur. This prevents the sensor unit from being damaged even if a discharge or the like occurs in a high-voltage environment of 600 V or more.

[0023] (8) The sensor unit may be installed in an environment where a voltage difference of 1100 V or more may occur. This prevents the sensor unit from being damaged even if a discharge or the like occurs in a high-voltage environment of 1100 V or more.

[0024] (9) The sensor unit can be installed in an environment where the magnetic or magnetic field sensed by the detection unit detecting the emitted light contains frequency components of 1 kHz or less. This makes it possible to detect magnetic fields that change instantaneously in a pulse-like manner, and to detect abnormalities such as partial discharge.

[0025] (10) The sensor unit may be installed in an environment where the magnetism or magnetic field sensed by the detection unit detecting the emitted light contains frequency components of 100 Hz or less. This allows the detection target to be an AC magnetic field generated by power transmission in power transmission facilities, etc., making it possible to detect abnormalities in the power transmission facilities, etc.

[0026] (11) The diamond magnetic sensor unit can further include an application unit that applies alternating magnetic, magnetic, potential, and electric field patterns in combination over time, in addition to irradiating the diamond with excitation light from the excitation light irradiation unit, thereby enabling accurate detection of magnetic fields.

[0027] (12) The spin coherence time of diamond may be less than 50 μsec. This allows the NV center to quickly return from an excited state to its original state, enabling efficient detection of alternating magnetic and electric fields. In particular, it becomes possible to detect magnetic and electric fields that change in a pulsed manner.

[0028] (13) The total hydrogen concentration in diamond can be greater than 0 ppm and less than 10 ppm, which shortens the spin coherence time T2 of the diamond and allows the NV center to quickly return from an excited state to its original state, enabling efficient detection of AC magnetic and electric fields.

[0029] (14) The total hydrogen concentration in the diamond may be greater than 0 ppm and less than 1 ppm. - The electron moves from the center to the hydrogen side, and the center no longer functions (NV 0 This can appropriately shorten the spin coherence time T2 of diamond while suppressing the spin-coherence time T2 (which becomes 0.01). The NV center quickly returns from the excited state to its original state, allowing for efficient detection of AC magnetic and electric fields without reducing detection sensitivity.

[0030] (15) NVH in diamond - The concentration, CH concentration, and CH2 concentration may all be greater than 0 ppm and less than 10 ppm. This shortens the spin coherence time T2 of the diamond, allowing the NV center to quickly return from an excited state to its original state. Therefore, it is possible to efficiently detect alternating magnetic and electric fields, including pulse-changing magnetic and electric fields.

[0031] (16) NVH in diamond - The concentration, CH concentration, and CH2 concentration may all be greater than 0 ppm and less than or equal to 1 ppm. - Electrons move from the center to the hydrogen side, forming NV - It will no longer function as a center (NV 0 This can appropriately shorten the spin coherence time T2 of diamond while suppressing the spin-induced excitation (becoming a lattice constant). Because the NV center quickly returns from the excited state to its original state, it can efficiently detect alternating magnetic and electric fields, including pulse-changing magnetic and electric fields, without reducing detection sensitivity.

[0032] (17) A diamond magnetic sensor system according to a second aspect of the present disclosure includes the diamond magnetic sensor unit, an application unit, and a control unit that controls the excitation light irradiation unit, the detection unit, and the application unit, and the control unit applies to the diamond, together with the excitation light, a time-combined pattern of alternating magnetic, magnetic, potential, and electric field by the application unit. This makes it possible to accurately detect magnetic fields without being damaged in a high-voltage environment.

[0033] [Details of the embodiments of the present disclosure] In the following embodiments, the same components are denoted by the same reference numerals, and their names and functions are also the same, so detailed descriptions thereof will not be repeated.

[0034] (First embodiment) 2, the diamond magnetic sensor unit 100 according to the first embodiment of the present disclosure includes an excitation light generating section 106, a fluorescence reflecting filter 110, an optical waveguide 112, a sensor section 120, an LPF 122, and a light receiving section 128. A control section 142 is disposed outside the diamond magnetic sensor unit 100.

[0035] The control unit 142 includes a CPU (Central Processing Unit) and a storage unit (neither of which are shown). The processing performed by the control unit 142, which will be described later, is realized by the CPU reading and executing a program stored in advance in the storage unit.

[0036] The excitation light generating unit 106 includes a light emitting element 102 and a light collecting element 104. Under the control of the control unit 142, the light emitting element 102 collects the NV of diamond, which will be described later. -The light-collecting element 104 collects the excitation light output from the light-emitting element 102. The light-collecting element 104 is used to input as much of the excitation light as possible that is diffused and output from the light-emitting element 102 into the light-incident end of the optical waveguide 112, which will be described later. The light-collecting element 104 preferably outputs parallel light that is collected within an area smaller than the size of the light-incident end of the optical waveguide 112 (for example, the core diameter, in the case of an optical fiber, of the core diameter).

[0037] The fluorescence reflection filter 110 is an element for separating the excitation light incident from the light-collecting element 104 from the light (i.e., fluorescence) emitted from the diamond, which will be described later. For example, the fluorescence reflection filter 110 is a short-pass filter that passes light with wavelengths equal to or less than a predetermined wavelength and cuts (i.e., reflects) light with wavelengths greater than the predetermined wavelength, or a band-pass filter that passes light with wavelengths within a predetermined wavelength range and cuts (i.e., reflects) light with wavelengths outside the predetermined wavelength range. Generally, excitation light has a shorter wavelength than fluorescence, so such a configuration is preferable. The fluorescence reflection filter 110 is preferably a dichroic mirror with this function.

[0038] The optical waveguide 112 includes a medium for transmitting light and transmits light bidirectionally. That is, it transmits the excitation light incident on the first end located on the excitation light generating unit 106 side to the second end located on the sensor unit 120 side. It also transmits the emitted light (i.e., fluorescence) from the diamond element 116 incident on the second end to the first end. The optical waveguide 112 is, for example, an optical fiber. To increase the energy density of the transmitted excitation light, it is preferable that the core diameter of the optical fiber be as small as possible. On the other hand, if the core diameter is too small, the efficiency of inputting the light diffused and emitted from the light source (i.e., the light-emitting element) into the optical fiber decreases. Therefore, there is an appropriate core diameter. For example, the core diameter of the optical fiber is approximately 80 μm or less and 1 μm or more.

[0039] The sensor unit 120 includes a light-collecting element 114 and a diamond element 116. The diamond element 116 includes an NV center. The light-collecting element 114 is arranged in contact with the diamond element 116. The light-collecting element 114 converges the excitation light output from the optical waveguide 112 and irradiates it onto the diamond element 116. That is, the control unit 142 controls the light-emitting element 102 to output the excitation light for a predetermined time (t1) at a predetermined timing. After a predetermined time (t2) has elapsed since the excitation light was output, the control unit 142 captures the output signal of the light detection unit 126 for a predetermined time (t3) at a predetermined timing and stores it in a memory unit.

[0040] The NV center has a structure in which a carbon (C) atom in a diamond crystal is replaced with a nitrogen (N) atom, and the carbon atom that should be adjacent to it does not exist (i.e., a vacancy (V)). The NV center is in a state where one electron is captured (i.e., NV - ), the magnetic quantum number m s forms a spin triplet state of -1, 0, +1, and in the absence of an external magnetic field, m s The energy levels of the states m = ±1 are degenerate (shown by two lines for convenience). In the presence of an external magnetic field, as shown in Figure 3B, sThe energy levels of the =±1 state are separated according to the magnetic field strength (Zeeman separation). When exposed to green light with a wavelength of approximately 490 to 560 nm (e.g., 532 nm laser light), the NV center transitions from the ground state E1 to the excited state E2 while maintaining its spin state, and then, for example, passes through the intermediate state E3 and returns to the ground state E1 by emitting light. At this time, red light with a wavelength of approximately 630 to 800 nm is emitted.

[0041] In the conventional microwave method, microwaves of about 2.87 GHz are irradiated to the NV center, and m s = 0 state is m s After causing a transition to the state of =±1 (i.e., electron spin resonance), it is excited by irradiating it with green light. As a result, the transition back to the ground state includes a transition that does not emit light (i.e., fluorescence), so the intensity of the observed emitted light decreases. Therefore, a valley (i.e., a drop in the signal) is observed in the ESR (Electron Spin Resonance) spectrum. The position (i.e., frequency) of the observed valley depends on the external magnetic field that the NV center receives, so by observing the valley, the magnetic field at the position of the NV center can be detected.

[0042] In contrast, in the present disclosure, after irradiating the NV center with excitation light, the emitted light is measured without irradiating it with electromagnetic waves such as microwaves, and the magnetic field at the position of the NV center is detected. Specifically, the measurement is performed in the same manner as disclosed in Non-Patent Documents 1 to 3, etc. The method of detecting the magnetic field without irradiating it with electromagnetic waves uses the PL or decoherence characteristics of the NV center under the influence of an external magnetic field.

[0043] For example, after irradiation with excitation light, the intensity of the PL emitted from the NV center decays exponentially over time, the extent of which depends on the external magnetic field, with the stronger the external magnetic field, the faster the decay. For example, the measured value of PL can be approximated by a triple exponential function with respect to the measurement time (see Non-Patent Document 2). Therefore, for example, if the relationship between the external magnetic field and the extent of decay of the observed PL signal intensity is derived in advance for the diamond to be used, the external magnetic field can be detected and the magnetic field strength can be determined from the PL value measured at a predetermined time after irradiation with excitation light. To detect the magnetic field with high precision, it is preferable to use microwaves, but even without microwaves, magnetic fields of about 10 mT to 20 mT can be detected in this manner. Here, it is desirable to align the crystal orientation of the diamond with the {100} direction relative to the direction of the external field to be measured, such as the external magnetic field. In this way, the sp of the diamond can be detected. 3 Join (sp 3 All NV centers that can be formed in four directions (depending on the hybrid orbital bonding) sense the external field isotropically, resulting in the highest contrast ratio (i.e., the signal-to-noise ratio). If they deviate from this direction, for example, if the NV center's direction is perpendicular to the magnetic field, the NV center loses its magnetic sensitivity. Therefore, only the NV centers that are not perpendicular to the magnetic field among the four directions have contrast, and their sensitivity as a sensor decreases.

[0044] A characteristic called GSLAC (ground-state level anti-crossing) can also be used (see Non-Patent Document 1). Specifically, an external magnetic field of approximately 102.4 mT causes degeneracy and mixing (i.e., anti-crossing) of the Zeeman sublevels of the NV center, which can be observed as a decrease in fluorescence intensity under optical excitation. In other words, when the NV center is exposed to a certain magnetic field, the fluorescence of the NV center changes, and this change can be measured. This method requires two electromagnets to apply a static magnetic field and a perturbation magnetic field. For example, one electromagnet (e.g., an air-core coil) is used to apply a sweeping magnetic field (e.g., changing from 0 to 120 mT in 5 seconds) to the NV center, and the other is used to apply a small perturbation magnetic field (e.g., amplitude approximately 0.1 mT, frequency 100 kHz). The diamond is irradiated with excitation light while applying a sweeping magnetic field and a perturbation magnetic field using the local oscillator of the lock-in amplifier. The process of detecting PL using the lock-in amplifier is repeated. As a result, when the magnetic field at the NV center position (i.e., the combined magnetic field of the sweep magnetic field and the external magnetic field of the detection target) reaches approximately 102.4 mT, GSLAC is observed in the PL measurement signal, and the external magnetic field of the detection target can be detected using the sweep magnetic field at that time. It is also possible to detect a valley in the PL measurement signal observed around approximately 51.4 mT. This valley is due to cross-relaxation between the NV center and the surrounding P1 centers (single substitutional nitrogens that act as electron donors). The external magnetic field of the detection target can be detected using the sweep magnetic field at that time.

[0045] Alternatively, a method of detecting the valley of the T1 relaxation time (longitudinal relaxation time) due to cross relaxation between the NV center and the surrounding P1 center, which is observed around 512 G (51.2 mT), may be used (see Non-Patent Document 3). In this case, an electromagnet is also required to apply a sweeping magnetic field to the diamond.

[0046] Specifically, PL is measured as follows. That is, the light (i.e., fluorescence) diffused and emitted from the diamond element 116 is collected by the collecting element 114 and converted into parallel light, which is input to the second end of the optical waveguide 112. In FIG. 2, the optical path of the emitted light is indicated by a dashed line. The light (i.e., fluorescence) input to the optical waveguide 112 is transmitted through the optical waveguide 112 and output from the first end of the optical waveguide 112. The light (i.e., fluorescence) output from the first end of the optical waveguide 112 is reflected by the fluorescence reflection filter 110, passes through the LPF 122, is collected by the collecting element 124, and is incident on the optical detection unit 126. As a result, the light affected by the magnetic field at the position where the diamond element 116 is placed is detected by the optical detection unit 126. The optical detection unit 126 generates and outputs an electrical signal corresponding to the incident light. The optical detection unit 126 is, for example, a photodiode. The output signal of the light detection unit 126 is acquired by the control unit 142 .

[0047] LPF 122 is a long-pass filter that passes light with wavelengths equal to or greater than a predetermined wavelength and cuts (for example, reflects) light with wavelengths smaller than the predetermined wavelength. The emitted light from diamond element 116 is red light and passes through LPF 122, but the excitation light has a shorter wavelength and does not pass through LPF 122. This prevents the excitation light emitted from light-emitting element 102 from being detected by light detection unit 126 and becoming noise, and therefore prevents a decrease in the detection sensitivity of the emitted light (i.e., fluorescence) from diamond element 116.

[0048] As described above, the control unit 142 can irradiate the diamond element 116 with excitation light and acquire the light (i.e., fluorescence) emitted from the diamond element 116 as an electrical signal output from the light detection unit 126. The magnetic field strength at the position of the diamond element 116 can be calculated from the observed emitted light. In other words, the diamond magnetic sensor unit 100 functions as a magnetic sensor. Note that the diamond sensor unit 100 can also be used as a sensor for detecting not only magnetic fields but also physical quantities related to magnetic fields, such as magnetization, electric fields, voltage, current, temperature, and pressure.

[0049] The sensor unit 120 does not include a conductive member that transmits electromagnetic waves, such as a microwave irradiation coil, and the diamond element 116, which is the main body of the sensor, and the light-collecting element 114 are formed from electrical insulators. In other words, the sensor unit 120 is formed entirely from electrical insulating materials. Therefore, even in a high-voltage environment, the sensor unit itself will not be damaged by partial discharge or the like, and magnetic fields can be detected with high accuracy.

[0050] By using an optical fiber for the optical waveguide 112, even if the sensor unit 120 and the second end of the optical waveguide 112 are installed in high-voltage equipment, the effects of partial discharges and the like can be prevented from reaching the excitation light generating unit 106 and the light receiving unit 128. Furthermore, the excitation light generating unit 106 and the light receiving unit 128 can be located away from high-voltage environments via the optical waveguide 112, allowing the diamond magnetic sensor unit 100 to measure magnetic fields and the like remotely. Furthermore, the sensor unit 120 includes a focusing element 114 disposed between the diamond element 116 and the optical waveguide 112, thereby reducing loss of excitation light and emitted light and improving detection accuracy. Furthermore, by providing a fluorescence reflection filter 110 that separates the excitation light from the emitted light and transmitting the excitation light and emitted light through a single medium (e.g., the optical waveguide 112), the number of components can be reduced and the configuration can be simplified compared to when two media are provided for transmitting the excitation light and the emitted light, as described below.

[0051] The diamond magnetic sensor unit 100 may include a conductive member that transmits electromagnetic waves that affect the NV centers of the diamond. If a conductive member is included, it is preferable that the conductive member be spaced 10 mm or more from the sensor unit 120. This allows for accurate detection of the magnetic field. It is more preferable that the conductive member be spaced 50 mm or more from the sensor unit 120. This allows for improved detection accuracy. It is even more preferable that the conductive member be spaced 100 mm or more. This allows for further improved detection accuracy. Note that, because the actual dimensions of the lens holder, optical fiber plug, and receptacle are approximately 10 mm, if the separation distance is less than 10 mm, there is a risk of the effects of electromagnetic field nonuniformity. In other words, this could be the starting point for dielectric breakdown, or could lead to equipment failure, such as arc discharge from power lines when a sudden potential change occurs, such as during a lightning strike.

[0052] The sensor unit may be installed in or around equipment (e.g., a transformer or solar power generation equipment) that normally generates a voltage difference of 200 V or more. Hereinafter, the equipment and its surroundings (i.e., an area within a predetermined range from the equipment) are collectively referred to as the "environment." The sensor unit may also be installed in an environment (e.g., a substation, a high-voltage power transmission line, a power distribution line, or a wind power generation equipment) that normally generates a voltage difference of 600 V or 1100 V or more. Even if a discharge or the like occurs in such an environment, the sensor unit can avoid damage and can accurately detect the magnetic field.

[0053] (Second embodiment) In the first embodiment, one optical waveguide 112 was used to transmit light (i.e., excitation light and emitted light) in both directions, but in the second embodiment, optical waveguides are used to transmit each of the excitation light and emitted light of the diamond element 116. Referring to Figure 4, a diamond magnetic sensor unit 200 according to the second embodiment of the present disclosure includes an excitation light generating section 206, a first optical waveguide 212, a focusing element 208, a fluorescence reflection filter 210, a sensor section 220, an LPF 222, a focusing element 224, a second optical waveguide 230, and a light receiving section 228. As in the first embodiment, a control section 142 is arranged outside the diamond magnetic sensor unit 200.

[0054] The excitation light generating unit 206 includes a light-emitting element 202 and a light-collecting element 204. The sensor unit 220 includes a light-collecting element 214 and a diamond element 216. The light-receiving unit 228 includes a light-detecting unit 226. The light-emitting element 202, the light-collecting element 204, the fluorescence reflection filter 210, the light-collecting element 214, the diamond element 216, the LPF 222, and the light-detecting unit 226 correspond to the light-emitting element 102, the light-collecting element 104, the fluorescence reflection filter 110, the light-collecting element 114, the diamond element 116, the LPF 122, and the light-detecting unit 126 shown in FIG. 2, respectively, and function in the same manner. Therefore, they will only be briefly described. In FIG. 4, as in FIG. 2, the optical path of the excitation light is indicated by a dotted line, and the optical path of the emitted light is indicated by a dashed line.

[0055] As in the first embodiment, the light-emitting element 202 generates excitation light for exciting the NV center of diamond under the control of the control unit 142. The control unit 142 supplies, for example, a voltage to the light-emitting element 202 at a predetermined timing to cause the light-emitting element 202 to emit light. The excitation light is green light. The excitation light is preferably laser light, and the light-emitting element 202 is preferably a semiconductor laser. The light-collecting element 204 collects the excitation light diffused and output from the light-emitting element 202, and inputs it to the light-incident end of the first optical waveguide 212.

[0056] The first optical waveguide 212 includes a medium for transmitting light. Unlike the optical waveguide 112 shown in FIG. 2, the first optical waveguide 212 transmits excitation light but does not transmit radiation light from the diamond element 216. That is, excitation light incident on the input end of the first optical waveguide 212, which is located on the excitation light generating unit 206 side, is transmitted to and output from the output end located on the sensor unit 220 side. The first optical waveguide 212 is, for example, an optical fiber. The excitation light diffused and output from the first optical waveguide 212 is collected by the collecting element 208 and enters the fluorescence reflecting filter 210 as parallel light.

[0057] The fluorescence reflection filter 210 is an element for separating the excitation light incident from the light-collecting element 208 from the light (i.e., fluorescence) emitted from the diamond element 216. The fluorescence reflection filter 210 may be a dichroic mirror.

[0058] The light-collecting element 214 converges the excitation light that has passed through the fluorescence reflection filter 210 and is input, and irradiates the diamond element 216. The light-collecting element 214 is disposed in contact with the diamond element 216. The diamond element 216 includes an NV center. The timing of irradiating the diamond element 216 with the excitation light is controlled by the control unit 142. This causes red light (i.e., fluorescence) to be emitted from the diamond element 216, as described above.

[0059] The light diffused and emitted from the diamond element 216 (i.e., red fluorescence) is collected by the light collecting element 214 to become parallel light, and enters the fluorescence reflection filter 210. The light incident on the fluorescence reflection filter 210 (i.e., red fluorescence) is reflected by the fluorescence reflection filter 210 and enters the LPF 222. The emitted light from the diamond element 216 (i.e., red fluorescence) that enters the LPF 222 passes through the LPF 222, is collected by the light collecting element 224, and enters the incident end of the second optical waveguide 230. The LPF 222 prevents the excitation light emitted from the light-emitting element 202 from being detected by the light detecting unit 226 and becoming noise, and therefore prevents a decrease in the detection sensitivity of the emitted light from the diamond element 216 (i.e., fluorescence).

[0060] The second optical waveguide 230 includes a medium for transmitting light. The second optical waveguide 230 transmits light incident on the incident end from the light-collecting element 224 (i.e., light emitted from the diamond element 216) to the output end arranged on the light-receiving unit 228 side. The light output from the second optical waveguide 230 is detected by the light detection unit 226. The light detection unit 226 is, for example, a photodiode. The output signal of the light detection unit 226 is acquired by the control unit 142.

[0061] As described above, the control unit 142, like the first embodiment, can irradiate the diamond element 216 with excitation light and acquire the light (i.e., fluorescence) emitted from the diamond element 216 as an electrical signal output from the light detection unit 226. Therefore, the diamond magnetic sensor unit 200 functions as a magnetic sensor. The diamond magnetic sensor unit 200 can be used as a sensor for detecting not only magnetic fields but also physical quantities related to magnetic fields, such as magnetization, electric fields, voltage, current, temperature, and pressure.

[0062] The sensor unit 220 does not include a conductive member that transmits electromagnetic waves, such as a microwave irradiation coil, and the diamond element 216, which is the main body of the sensor, and the light-collecting element 214 are formed from electrical insulators. In other words, the sensor unit 220 is formed entirely from electrical insulating materials. Therefore, even in a high-voltage environment, the sensor unit itself will not be damaged by partial discharge or the like, and magnetic fields can be detected with high accuracy.

[0063] By using optical fibers for the two optical waveguides (i.e., the first optical waveguide 212 and the second optical waveguide 230), even if the sensor unit 220 is installed in high-voltage equipment, the effects of partial discharges and the like can be prevented from reaching the excitation light generating unit 206 and the light receiving unit 228. Furthermore, the excitation light generating unit 206 and the light receiving unit 228 can be located away from high-voltage environments via the first optical waveguide 212 and the second waveguide 230, making it possible to measure magnetic fields and the like remotely using the diamond magnetic sensor unit 200. Furthermore, the sensor unit 220 includes a focusing element 214 located between the diamond element 216 and the first optical waveguide 212 and the second waveguide 230, thereby reducing loss of excitation light and emitted light and improving detection accuracy.

[0064] By using two optical waveguides (i.e., the first optical waveguide 212 and the second optical waveguide 230), the excitation light and the emitted light from the diamond element 216, which have different wavelengths, can be appropriately transmitted. That is, by using an optical fiber with a core diameter according to the wavelength, it is possible to design a focusing optical system (i.e., the focusing elements 204, 208, 214, and 224) suitable for each, thereby improving the light transmission efficiency and the detection accuracy. When an optical fiber is used as the optical waveguide, it is preferable that the core diameter of the optical fiber (i.e., the second optical waveguide 230) that transmits the emitted light from the diamond is larger than the core diameter of the optical fiber (i.e., the first optical waveguide 212) that transmits the excitation light.

[0065] As mentioned above, the optical fiber used to transmit the excitation light should have a small core diameter in order to increase the energy density of the excitation light, but if the core diameter is too small, loss occurs when light is input from the light source to the fiber. Therefore, there is an appropriate core diameter. The core diameter of the first optical waveguide 212 is preferably 1 μm or more and 100 μm or less. On the other hand, the larger the core diameter of the optical fiber for transmitting the emitted light from the diamond element 216, the more preferable it is. However, if the core diameter is too large, the cost will be high. The core diameter of the second optical waveguide 230 is preferably 1 μm or more and 1 mm or less.

[0066] (First Modification) In the second embodiment, the excitation light and the emitted light from the diamond element 216 are separated using the fluorescence reflection filter 210, but this is not limiting. The excitation light and the emitted light from the diamond element 216 may also be separated using an LPF.

[0067] 5, the diamond magnetic sensor unit 300 according to the first modification uses an LPF 302 to separate the excitation light from the light emitting element 202 and the emitted light from the diamond element 216. The diamond magnetic sensor unit 300 is the diamond magnetic sensor unit 200 (see FIG. 4) in which the fluorescence reflection filter 210 is replaced with an LPF 302, and the path for generating and transmitting the excitation light and the path for transmitting and detecting the emitted light from the diamond element 216 are interchanged. The LPF 302 is a long-pass filter. In FIG. 5, components with the same reference numerals as in FIG. 4 represent the same components as in FIG. 4. Therefore, redundant explanations regarding them will not be repeated. In FIG. 5, as in FIG. 4, the optical path of the excitation light is indicated by a dotted line, and the optical path of the emitted light is indicated by a dashed line.

[0068] The excitation light generated by the light-emitting element 202 is collected by the light-collecting element 204 and input to the incident end of the first optical waveguide 212. The excitation light is transmitted through the first optical waveguide 212, output from the output end of the first optical waveguide 212, collected by the light-collecting element 224 to become parallel light, and then enters the LPF 302. Since the excitation light is green light, it is reflected by the LPF 302 and enters the light-collecting element 214.

[0069] On the other hand, the light emitted from the diamond element 216 is collected by the collecting element 214 to become parallel light, and enters the LPF 302. The light emitted from the diamond element 216 (i.e., red fluorescence) passes through the LPF 302, is collected by the collecting element 224, enters the second optical waveguide 230, is transmitted by the second optical waveguide 230 to the light receiving unit 228, and is detected by the light receiving unit 228. Therefore, similar to the diamond magnetic sensor unit 200 of the second embodiment, the diamond magnetic sensor unit 300 functions as a sensor that detects magnetic fields, etc.

[0070] (Second Modification) In the above, the case where excitation light is incident on one surface of the diamond element containing NV center and the radiation light from the same surface is measured has been described, but this is not limited to this.When the diamond element containing NV center has multiple flat surfaces, the surface that is irradiated with excitation light and the surface that measures the radiation light may be different.A flat surface means a single plane that has an area of ​​at least a predetermined size, and here, the flat surface of the diamond element containing NV center means a single plane that has an area larger than a circle with a diameter of about 200 μm.

[0071] 6, a diamond magnetic sensor unit 400 according to the second modification detects light emitted from a surface of a diamond element 402 different from the surface on which excitation light is incident. The diamond magnetic sensor unit 400 is the diamond magnetic sensor unit 200 shown in FIG. 4, in which the sensor unit 220 is replaced with a sensor unit 408, and the light-collecting element 208, the fluorescence reflection filter 210, and the light-collecting element 224 have been removed. In FIG. 6, components with the same reference numerals as in FIG. 4 represent the same components as in FIG. 4. Duplicate explanations of these components will not be repeated. In FIG. 6, as in FIG. 4, the optical path of the excitation light is indicated by a dotted line, and the optical path of the emitted light is indicated by a dashed line.

[0072] The sensor unit 408 includes a diamond element 402, a light-collecting element 404, and a light-collecting element 406. The diamond element 402 includes an NV center and has a plurality of flat surfaces. The diamond element 402 is formed, for example, in the shape of a rectangular parallelepiped. The light-collecting element 404 is arranged in contact with one flat surface (hereinafter referred to as a first flat surface) of the diamond element 402. The light-collecting element 406 is arranged in contact with a flat surface (hereinafter referred to as a second flat surface) of the diamond element 402 that is different from the first flat surface.

[0073] The excitation light transmitted by the first optical waveguide 212 enters the focusing element 404, is focused by the focusing element 404, and irradiates the first flat surface of the diamond element 402. As described above, irradiation of the diamond element 402 with excitation light at a predetermined timing causes light to be emitted from the diamond element 402. The emitted light is emitted in all directions. The light emitted from the second flat surface of the diamond element 402 (i.e., red fluorescence) is focused by the focusing element 406 to become parallel light, enters the LPF 222, passes through the LPF 222, and enters the incident end of the second optical waveguide 230. The light emitted from the second flat surface of the diamond element 402 (i.e., red fluorescence) is then transmitted by the second optical waveguide 230 to the optical detection unit 226 and detected by the optical detection unit 226. Therefore, similar to the diamond magnetic sensor unit 200 of the second embodiment, the diamond magnetic sensor unit 400 functions as a sensor for detecting magnetic fields, etc.

[0074] In this way, by configuring the sensor to detect radiation from a surface (i.e., the second flat surface) different from the surface irradiated with excitation light (i.e., the first flat surface), the number of focusing elements can be reduced, and the elements (e.g., fluorescent reflection filters) for separating the excitation light from the radiation from the diamond element can be reduced. Therefore, the diamond magnetic sensor unit can be made simpler in configuration and costs can be reduced.

[0075] In the above, a case has been described in which diamond element 402 is formed into a rectangular parallelepiped, and the first flat surface and the second flat surface are two surfaces that form an angle of 90 degrees, but this is not limiting. When diamond element 402 is formed into a rectangular parallelepiped, a flat surface parallel to the first flat surface may be used as the second flat surface that collects the radiation light to be detected. Furthermore, diamond element 402 only needs to have at least two flat surfaces, and is not limited to a hexahedron, and the shape of diamond element 402 is arbitrary.

[0076] (Third Modification) Although the case where the sensor unit includes a focusing element has been described above, this is not limiting. Referring to FIG. 7, the diamond magnetic sensor unit 500 according to the third modification is obtained by removing the focusing element 114 from the diamond magnetic sensor unit 100 shown in FIG. 2. That is, the sensor unit 502 includes a diamond element 116 but does not include a focusing element. The diamond element 116 is arranged in contact with the second end of the optical waveguide 112.

[0077] In the diamond magnetic sensor unit 500, similarly to the diamond magnetic sensor unit 100 (see FIG. 2), when the excitation light (i.e., green light) output from the light-emitting element 102 is irradiated onto the diamond element 116, the NV center of the diamond element 116 is excited, emits light (i.e., red fluorescence), and returns to its original state. Therefore, by measuring the emitted light, the diamond magnetic sensor unit 500 functions as a magnetic sensor. The method of measuring the magnetic field is the same as in the first embodiment.

[0078] The sensor unit 502 does not include conductive members such as coils, and is made entirely of electrically insulating materials. Therefore, even if the sensor unit 502 is installed in high-voltage equipment, it will not be damaged by discharge or the like, and can safely measure magnetic fields and the like in a high-voltage environment.

[0079] (Fourth Modification) In the first and second embodiments, the optical waveguide for transmitting the excitation light and the emitted light from the diamond element is configured using a medium for transmitting light, but this is not limited to this. The diamond magnetic sensor unit according to the fourth modification uses a mirror to configure the optical waveguide. Specifically, referring to FIG. 8, the diamond magnetic sensor unit 600 includes an excitation light generating unit 106, a sensor unit 120, an LPF 122, a light receiving unit 128, a concave mirror 602, and a convex mirror 604. As in the first embodiment, a control unit 142 is arranged outside the diamond magnetic sensor unit 600.

[0080] The excitation light generating unit 106 includes a light emitting element 102 and a light collecting element 104. The sensor unit 120 includes a light collecting element 114 and a diamond element 116. The light receiving unit 128 includes a light detecting unit 126. In Figure 8, components with the same reference numerals as in Figure 2 represent the same components as in Figure 2. Therefore, redundant description of those components will not be repeated.

[0081] The concave mirror 602 has a shape obtained by cutting a sphere of radius r1 centered at point O with a plane. The shape of the end (i.e., the cut portion) of the concave mirror 602 is a circle with a diameter d1. The concave mirror 602 has an opening 606 for passing the excitation light from the excitation light generating unit 106 and an opening 608 for passing the emitted light. The openings 606 and 608 are, for example, circular. Of the two curved surfaces (i.e., parts of the spherical surface) on both sides of the concave mirror 602, the curved surface facing the convex mirror 604 is a reflecting surface for the emitted light (hereinafter referred to as the mirror surface). The convex mirror 604 has a shape obtained by cutting a sphere of radius r2 centered at point O with a plane. The shape of the end (i.e., the cut portion) of the concave mirror 602 is a circle with a diameter d2. Of the two curved surfaces (i.e., parts of the spherical surface) on both sides of the convex mirror 604, the curved surface facing the concave mirror 602 is a mirror surface.

[0082] 8, as in FIG. 2, the optical path of the excitation light is indicated by a dotted line, and the optical path of the emitted light is indicated by a dashed line. The excitation light generated by the light-emitting element 102 is focused by the focusing element 104 to become parallel light, which propagates through space and enters the focusing element 114, where it is focused and irradiates the diamond element 116. In other words, the space functions as an optical waveguide for the excitation light, and the space constitutes the optical waveguide for the excitation light. Meanwhile, the emitted light from the diamond element 116 is reflected sequentially by the concave mirror 602 and the convex mirror 604, and enters the light-receiving unit 128 through the opening 608. Therefore, the concave mirror 602, the convex mirror 604, and the space constitute an optical waveguide for the emitted light. As a result, like the diamond magnetic sensor unit 100 of the first embodiment, the diamond magnetic sensor unit 600 functions as a sensor for detecting magnetic fields, etc.

[0083] In the above description, the centers of both concave mirror 602 and convex mirror 604 are located at point O, but the centers of concave mirror 602 and convex mirror 604 may be located at different positions. Also, the case where each end of concave mirror 602 and convex mirror 604 is circular (i.e., a shape obtained by cutting a sphere with a plane) has been described, but this is not limiting. As long as the opposing surfaces of concave mirror 602 and convex mirror 604 are mirror surfaces, the shapes of each end of concave mirror 602 and convex mirror 604 are arbitrary.

[0084] In the second embodiment (see FIG. 4), the first modified example (see FIG. 5), and the second modified example (see FIG. 6), the excitation light is transmitted through an optical waveguide 212 such as an optical fiber, but this is not limiting. For example, the diamond magnetic sensor unit 200 (see FIG. 4) and the diamond magnetic sensor unit 300 (see FIG. 5) may not include the optical waveguide 212 and the focusing element 208. The excitation light output from the light-emitting element 202 is focused by the focusing element 204 to become parallel light, so the focusing element 208 may not be required. The excitation light focused by the focusing element 204 is transmitted by the space itself and enters the fluorescence reflection filter 210 or the LPF 302. Similarly, the diamond magnetic sensor unit 400 (see FIG. 6) may not include the optical waveguide 212. The excitation light focused by the focusing element 204 is transmitted by the space itself and enters the focusing element 404.

[0085] In the above, we have described the case where a diamond element having an NV center is used in a diamond magnetic sensor unit, but this is not limited to this. Any diamond element having a color center with electronic spin will do. A color center with electronic spin is a center that forms a spin triplet state and emits light when excited, and the NV center is a typical example. In addition, it is known that color centers with electronic spin also exist in silicon-vacancy centers (i.e., Si-V centers), germanium-vacancy centers (i.e., Ge-V centers), and tin-vacancy centers (i.e., Sn-V centers). Therefore, diamond elements including these may be used instead of diamond elements including NV centers to construct a diamond magnetic sensor unit.

[0086] The excitation light is preferably a laser beam, and a semiconductor laser is more preferable as a generator because it can be made smaller. The detector for the emitted light from the diamond element may be a vacuum tube type, but a semiconductor detection device is more preferable because it can be made smaller.

[0087] The optical waveguide preferably has a coaxial structure of two or more layers, having a core portion through which light passes and a portion formed around the core and made of a material with a different refractive index from that of the core portion. The core portion does not have to be densely filled with a medium that transmits light. The core portion may be hollow, since the space itself can transmit light. The optical waveguide is preferably an optical fiber with a core diameter of 1 μm or more and 80 μm or less. This is because using an optical fiber makes it relatively easy to guide laser light to the desired location and also suppresses divergence at the output end of the optical fiber.

[0088] The focusing element may be made of any material that has the ability to focus light. For example, it may be a lens made of a silicon oxide-based material (e.g., glass, which may contain additives other than silicon oxide), or a material with diffractive properties. The focusing element is preferably a lens that transmits light and utilizes the phenomenon of refraction. Spherical lenses, hemispherical lenses, Fresnel lenses, etc. are preferred. In particular, lenses in which the focus of parallel light is located on a spherical surface due to the relationship between the refractive index and the spherical shape are more preferred. This is because using such a lens makes it very easy to adjust the optical focus and optical axis, allowing the maximum amount of light to be utilized.

[0089] When the sensor unit is placed in a high-voltage environment, it is preferable to place the optical waveguide (e.g., optical fiber) that transmits the excitation light and the emitted light from the diamond inside an insulator. This insulates the excitation light generating unit and the light receiving unit from high voltage and protects the devices used in the excitation light generating unit and the light receiving unit.

[0090] When using the above-mentioned diamond magnetic sensor unit to detect time-dependent changes in a fluctuating magnetic field, etc., targeting AC power, it is preferable that the NV center of the diamond element quickly returns from the state of emitting light to its original state (i.e., the state before excitation) after being excited. For this purpose, it is preferable that the spin coherence time T2 of the diamond element is short. For example, it is preferable that the spin coherence time T2 of the diamond element is less than 50 μsec. This allows the NV center to quickly return from the excited state to its original state, making it possible to efficiently detect AC magnetic and electric fields, etc. In particular, it becomes possible to detect magnetic and electric fields, etc. that change in a pulse-like manner. The detection sensitivity is (T2) -1 / 2 Therefore, when detecting sudden changes in magnetic field fluctuations, for example, when detecting pulsed magnetic field fluctuations, it is possible to sacrifice detection sensitivity and shorten the spin coherence time T2 of the diamond element as much as possible.

[0091] To shorten the spin coherence time, it is preferable that the diamond element contains impurities. Considering that the smaller T2 is, the lower the detection sensitivity is, for example, it is preferable that the total hydrogen concentration in the diamond is greater than 0 ppm and not more than 10 ppm. Here, the concentration (unit: ppm) represents the ratio of the number of atoms. This shortens the spin coherence time T2 of the diamond, and the NV center quickly returns from the excited state to its original state, allowing for efficient detection of alternating magnetic and electric fields. However, if the concentration of hydrogen atoms contained in the diamond becomes high, the NV - The electron on the center side moves to the hydrogen side, and the color sensor no longer functions (i.e., NV 0 Therefore, it is more preferable that the total hydrogen concentration in diamond is greater than 0 ppm and less than 1 ppm. - This can appropriately shorten the spin coherence time T2 of the diamond while suppressing the movement of electrons from the center to the hydrogen side, which causes the center to stop functioning.

[0092] Also, NVH in diamond -It is also preferable that each of the hydrogen atom concentration, CH concentration, and CH2 concentration is greater than 0 ppm and not more than 10 ppm. This shortens the spin coherence time T2 of the diamond, and the NV center quickly returns from the excited state to its original state, allowing for efficient detection of AC magnetic and electric fields. As described above, in order to suppress the concentration of hydrogen atoms contained in diamond, it is necessary to - It is more preferable that each of the concentration, CH concentration, and CH2 concentration is greater than 0 ppm and equal to or less than 1 ppm. - This can appropriately shorten the spin coherence time T2 of the diamond while preventing the electrons on the center side from moving to the hydrogen side and losing their function as a color center.

[0093] By using diamond with a short spin coherence time, the diamond magnetic sensor unit can be installed in an environment where the magnetic or magnetic field contains frequency components of 100 Hz or less and can detect the magnetic or magnetic field. For example, in power receiving and transforming facilities, the AC magnetic field generated by power transmission can be detected, making it possible to detect abnormalities in the power receiving and transforming facilities. Furthermore, by using diamond with an even shorter spin coherence time, the diamond magnetic sensor unit can be installed in an environment where the magnetic or magnetic field contains frequency components of 1 kHz or less and can detect the magnetic or magnetic field. For example, it can detect magnetic fields that change instantaneously in a pulsed manner, making it possible to detect abnormalities such as partial discharge.

[0094] In the above, we have explained the case where the diamond having a color center is irradiated with excitation light without irradiating it with electromagnetic waves, and the radiation emitted from the diamond is detected, but this is not limited to this. While irradiating the diamond with excitation light, it is also possible to detect the radiation emitted from the diamond by applying a temporally combined pattern of alternating magnetic, magnetic, potential, and electric fields. In this case, the diamond magnetic sensor unit includes an application device (for example, an electromagnet) for forming a temporally combined pattern of alternating magnetic, magnetic, potential, and electric fields. This allows for accurate detection of the magnetic field.

[0095] (Configuration of the Example) An example of the configuration shown in Figure 4 is shown in Figure 9. Figure 9 shows an arrangement in which the light-collecting element 214 and diamond element 216 that make up the sensor unit are placed near electrical wiring 260, an AC current (for example, 50 Hz or 60 Hz, 30 A) is passed through the electrical wiring 260, and the fluctuating magnetic field generated by this is the object of detection. In Figure 9, components corresponding to those shown in Figure 4 are given the same reference numerals as in Figure 4.

[0096] The first optical waveguide 212 and the second optical waveguide 230 are, for example, step-index multimode optical fibers. The first optical waveguide 212 has, for example, a core diameter of 50 μm and an NA (i.e., numerical aperture) of 0.2. The second optical waveguide 230 has, for example, a core diameter of 400 μm and an NA of 0.5. The diamond element 216 is, for example, a rectangular diamond having dimensions of 3 mm × 3 mm × 0.3 mm. The focusing element 214 is, for example, a spherical lens having a diameter of 2 mm, and is fixed in contact with the surface of the diamond element 216 (for example, a flat surface of 3 mm × 3 mm). The optical system that transmits the excitation light includes the focusing element 208, the fluorescence reflection filter 210, and a triangular prism 250, forming a collimating optical system. The collimating optical system adjusts the excitation light so that it enters the center of the focusing element 214.

[0097] The light detection unit 226 (see FIG. 4) uses, for example, a PIN-AMP (i.e., a photodiode IC having a linear current amplifier circuit). The PIN-AMP is, for example, a photo IC diode S7183 or S7184 (manufactured by Hamamatsu Photonics K.K.). This photo IC diode has a photodiode sensitivity wavelength range of 300 to 1000 nm and a maximum sensitivity wavelength of 650 nm, and amplifies the photocurrent generated by the photodiode by 1300 times and outputs the amplified signal.

[0098] Although the present disclosure has been described above by explaining the embodiments, the above-described embodiments are merely examples, and the present disclosure is not limited to only the above-described embodiments. The scope of the present disclosure is defined by the claims in the scope of the claims, taking into consideration the description of the detailed description of the invention, and includes all modifications within the meaning and scope equivalent to the wordings described therein. [Explanation of symbols]

[0099] 100, 200, 300, 400, 500, 600 Diamond magnetic sensor unit 102, 202 Light-emitting element 104, 114, 124, 204, 208, 214, 224, 404, 406 Condenser element 106, 206 Excitation light generating unit 110, 210 Fluorescence Reflection Filter 112 Optical waveguide 116, 216, 402 Diamond elements 120, 220, 408, 502 Sensor part 122, 222, 302, 908 LPF 126, 226 Light detection unit 128, 228 Light receiving section 142 Control Unit 212 1st optical waveguide 230 Second optical waveguide 250 Triangular Prism 260 Electrical Wiring 602 Concave mirror 604 Convex mirror 606, 608 aperture 912, 914, 916 boards 900 LED 902 SPF 904 Diamond 906 Lens 910 Photodiode E1, E2, E3 energy levels O point r1, r2 radius d1, d2 diameter

Claims

1. a sensor portion including a diamond having a color center with electron spin; an excitation light irradiating unit that irradiates the diamond with excitation light; a detector for detecting radiation from the color center of the diamond; the detection unit detects the radiation light generated when the excitation light is irradiated onto the diamond by the excitation light irradiator without irradiating the diamond with electromagnetic waves; The diamond magnetic sensor unit is installed in an environment where a voltage difference of 1100 V or more may occur.

2. A conductive member that transmits the electromagnetic waves, 2. The diamond magnetic sensor unit according to claim 1, wherein the conductive member is disposed at a distance of 50 mm or more from the sensor portion.

3. A conductive member that transmits the electromagnetic waves, 2. The diamond magnetic sensor unit according to claim 1, wherein the conductive member is disposed at a distance of 100 mm or more from the sensor portion.

4. 4. The diamond magnetic sensor unit according to claim 1, further comprising an optical waveguide for transmitting the excitation light and the emitted light.

5. 5. The diamond magnetic sensor unit according to claim 1, wherein the sensor portion having the diamond is entirely made of an electrically insulating material.

6. A sensor portion including a diamond having a color center with electron spin; an excitation light irradiating unit that irradiates the diamond with excitation light; a detector for detecting radiation from the color center of the diamond; the detection unit detects the radiation light generated when the excitation light is irradiated onto the diamond by the excitation light irradiator without irradiating the diamond with electromagnetic waves; The diamond magnetic sensor unit is configured such that the sensor unit is placed in an environment where the magnetism or magnetic field sensed by the detection unit detecting the radiation includes frequency components of 1 kHz or less.

7. A sensor portion including a diamond having a color center with electron spin; an excitation light irradiating unit that irradiates the diamond with excitation light; a detector for detecting radiation from the color center of the diamond; the detection unit detects the radiation light generated when the excitation light is irradiated onto the diamond by the excitation light irradiator without irradiating the diamond with electromagnetic waves; The diamond magnetic sensor unit is configured such that the sensor unit is installed in an environment where the magnetism or magnetic field sensed by the detection unit detecting the radiation includes frequency components of 100 Hz or less.

8. A sensor portion including a diamond having a color center with electron spin; an excitation light irradiating unit that irradiates the diamond with excitation light; a detector for detecting radiation from the color center of the diamond; the detection unit detects the radiation light generated when the excitation light is irradiated onto the diamond by the excitation light irradiator without irradiating the diamond with electromagnetic waves; The diamond magnetic sensor unit further includes an application unit that applies alternating magnetic, magnetic, potential and electric field patterns in combination over time, in conjunction with the irradiation of the excitation light by the excitation light irradiation unit onto the diamond.

9. 9. The diamond magnetic sensor unit according to claim 1, wherein the spin coherence time of the diamond is less than 50 μsec.

10. A sensor portion including a diamond having a color center with electron spin; an excitation light irradiating unit that irradiates the diamond with excitation light; a detector for detecting radiation from the color center of the diamond; the detection unit detects the radiation light generated when the excitation light is irradiated onto the diamond by the excitation light irradiator without irradiating the diamond with electromagnetic waves; A diamond magnetic sensor unit, wherein the total hydrogen concentration in the diamond is greater than 0 ppm and less than or equal to 10 ppm.

11. A sensor portion including a diamond having a color center with electron spin; an excitation light irradiating unit that irradiates the diamond with excitation light; a detector for detecting radiation from the color center of the diamond; the detection unit detects the radiation light generated when the excitation light is irradiated onto the diamond by the excitation light irradiator without irradiating the diamond with electromagnetic waves; A diamond magnetic sensor unit, wherein the total hydrogen concentration in the diamond is greater than 0 ppm and equal to or less than 1 ppm.

12. NVH in the diamond － concentration, CH concentration and CH ２ 9. The diamond magnetic sensor unit according to claim 1, wherein all of the concentrations are greater than 0 ppm and not more than 10 ppm.

13. NVH in the diamond － concentration, CH concentration and CH ２ 9. The diamond magnetic sensor unit according to claim 1, wherein any of the concentrations is greater than 0 ppm and equal to or less than 1 ppm.

14. The diamond magnetic sensor unit according to claim 8, a control unit that controls the excitation light irradiation unit, the detection unit, and the application unit, The control unit causes the application unit to irradiate the diamond with a temporally combined pattern of alternating magnetic, magnetic, potential and electric fields together with the excitation light.

Images