Diamond magnetic sensor unit and diamond magnetic sensor system

Abstract

A diamond magnetic sensor unit includes: a sensor portion including a diamond having a color center with an electron spin; an excitation light irradiation portion that irradiates the diamond with excitation light; and a detection portion that detects emission light from the color center of the diamond, the detection portion detecting emission light generated by the excitation light irradiation portion irradiating the diamond with excitation light without irradiating the diamond with an electromagnetic wave, the diamond magnetic sensor unit being capable of including an electrically conductive member disposed spaced apart from the sensor portion by 10 mm or more that propagates the electromagnetic wave.

Description

Technical Field

[0001] This disclosure relates to a diamond magnetic sensor unit and a diamond magnetic sensor system. This application claims priority based on Japanese Application No. 2021-010936, filed on January 27, 2021, and incorporates all the contents described in that Japanese application. Background Technology

[0002] Sensors using diamond NV centers are known. In cases where diamond NV centers are combined with microscopes, for example... Figure 1 The configuration is shown. Specifically, the LED 900, disposed on substrate 912, emits green light to excite the NV center of diamond 904. The emitted light, after passing through SPF (Short Pass Filter) 902, is incident on diamond 904 disposed on substrate 914. Thus, NV... - The central electron becomes excited. When the excited electron returns to its original ground state, red fluorescence is emitted from the diamond 904. This fluorescence is focused by lens 906 and, after passing through LPF (Long Pass Filter) 908, is detected by photodiode 910 disposed on substrate 916. Additionally, microwaves generated by an external device (not shown) are irradiated onto the diamond 904. Thus, if excited to different spin states and resonance states, the intensity of the red fluorescence from the diamond 904 changes. This change is detected by photodiode 910. Lens 906 can be a lens structure of a high-performance optical microscope or a simple lens structure.

[0003] Patent Document 1 discloses a scanning probe microscope (i.e., frequency-modulated atomic force microscope (FM-AFM)) using a diamond NV center. Patent Document 2 discloses a magnetic field detection device using a diamond NV center.

[0004] Non-Patent Document 1 discloses an experimental apparatus for detecting photoluminescence (hereinafter referred to as PL) emitted from a diamond containing an NV center by irradiating it with excitation light without irradiating it with microwaves. This experimental apparatus includes an electromagnet for applying a scanning magnetic field and a perturbation magnetic field of a predetermined frequency to the diamond. When PL is detected by irradiating the diamond with the excitation light while the scanning magnetic field and perturbation magnetic field are applied, the intensity of PL changes depending on the external magnetic field acting on the NV center.

[0005] Prior art literature

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2017-67650

[0008] Patent Document 2: Japanese Patent Application Publication No. 2018-136316

[0009] Non-patent literature

[0010] Non-patent document 1: Arne Wickenbrock, et al., "Microwave-free magnetometry with nitrogen-vacancy centers in diamond," Applied Physics Letters 109,053505(2016)

[0011] 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)

[0012] Non-patent document 3: LTHall, P.Kehayias, DASimpson, A.Jarmola, A.Stacey, D.Budker, and LCLHollenberg, "Detection of nanoscale electron spin resonancespectra demonstrated using nitrogen-vacancy center probes in diamond," Nat.Commun.7, 10211 (2016) Summary of the Invention

[0013] One aspect of this disclosure relates to a diamond magnetic sensor unit comprising: a sensor section including a diamond having a color center, the color center having an electron spin; an excitation light irradiation section for irradiating the diamond with excitation light; and a detection section for detecting the emitted light from the color center of the diamond. The detection section detects the emitted light generated by irradiating the diamond with excitation light by the excitation light irradiation section without irradiating the diamond with electromagnetic waves. The diamond magnetic sensor unit may include a conductive component disposed at a distance of 10 mm or more from the sensor section for propagating electromagnetic waves.

[0014] Other aspects of this disclosure relate to a diamond magnetic sensor system including: the aforementioned 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. The control unit applies alternating magnetic force, magnetic field, potential, and electric field to the diamond along with the excitation light through the application unit in a time-varying manner. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view of an existing NV center microscope that uses diamond.

[0016] Figure 2 This is a schematic diagram showing the general structure of the diamond magnetic sensor unit according to the first embodiment of this disclosure.

[0017] Figure 3A This is a diagram showing the energy levels and their migrations at the NV center in the absence of an external magnetic field.

[0018] Figure 3B This is a diagram showing the energy levels and their migrations at the NV center in the presence of an external magnetic field.

[0019] Figure 4 This is a schematic diagram showing the general structure of the diamond magnetic sensor unit according to the second embodiment of this disclosure.

[0020] Figure 5 This is a schematic diagram showing the general structure of the diamond magnetic sensor unit involved in the first modified example.

[0021] Figure 6 This is a schematic diagram showing the general structure of the diamond magnetic sensor unit involved in the second variation.

[0022] Figure 7 This is a schematic diagram showing the general structure of the diamond magnetic sensor unit involved in the third variation.

[0023] Figure 8 This is a schematic diagram showing the general structure of the diamond magnetic sensor unit involved in the fourth variation.

[0024] Figure 9This illustrates the second embodiment (see reference). Figure 4 A perspective view of an embodiment of ). Detailed Implementation

[0025] [The technical problem the invention aims to solve]

[0026] In the apparatuses disclosed in Patent Documents 1 and 2, microwaves need to be irradiated onto a diamond, including the NV center. Therefore, a microwave generating device, a microwave irradiation coil, and a mechanism for transmitting microwaves to the microwave irradiation coil disposed near the diamond are required, which increases costs.

[0027] When using sensors on high-voltage equipment such as power devices, high voltage and large current are instantaneously generated due to partial discharge, which also produces strong electromagnetic waves. If conductive components such as coils used for irradiating microwaves are present near the diamond, eddy currents will be generated, affecting the detection accuracy of the sensor. Therefore, it is preferable that there are no conductive components near the diamond. In addition, there is a possibility of damage to the light-emitting and light-receiving elements due to discharge.

[0028] The experimental apparatus disclosed in Non-Patent Document 1 focuses the emitted light from the diamond (i.e., the NV center) through 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 structure, if the photodiode is far from the diamond, the detection sensitivity of the emitted light decreases, therefore the photodiode needs to be placed near the diamond. Therefore, the structure disclosed in Non-Patent Document 1 cannot be used in sensors used in high-voltage environments (e.g., due to the effects of partial discharge).

[0029] Therefore, the purpose of this disclosure is to provide a diamond magnetic sensor unit and a diamond magnetic sensor system that are not damaged in high-voltage environments and can accurately detect magnetic fields (magnetic fields) at long distances.

[0030] [The effects of the invention]

[0031] According to this disclosure, a diamond magnetic sensor unit and a diamond magnetic sensor system can be provided that are not damaged in high-voltage environments and can accurately detect magnetic fields and electric fields over long distances.

[0032] [Description of embodiments of this disclosure]

[0033] The embodiments described herein are listed below. At least a portion of the embodiments described below may also be combined in any way.

[0034] (1) The diamond magnetic sensor unit according to the first aspect of this disclosure includes: a sensor unit comprising a diamond having a color center, the color center having an electron spin; an excitation light irradiation unit for irradiating excitation light onto the diamond; and a detection unit for detecting emitted light from the color center of the diamond. The detection unit detects emitted light generated by irradiating the diamond with excitation light by the excitation light irradiation unit without irradiating the diamond with electromagnetic waves. The diamond magnetic sensor unit may include a conductive component disposed at a distance of 10 mm or more from the sensor unit to propagate electromagnetic waves. Therefore, it will not be damaged even in high voltage environments above 1 kV and can detect magnetic fields with good accuracy.

[0035] (2) The conductive components can be positioned at a distance of 50mm or more from the sensor. Therefore, they will not be damaged even in high voltage environments of 5kV or above, thus improving detection accuracy.

[0036] (3) The conductive components can also be configured at a distance of more than 100mm from the sensor. Therefore, they will not be damaged even in high voltage environments above 10kV, which can further improve the detection accuracy.

[0037] (4) The diamond magnetic sensor unit can further include an optical waveguide for transmitting excitation light and emitted light. Therefore, even if discharge occurs in a high-voltage environment where the sensor unit is located, damage to the detection unit and the like can be prevented.

[0038] (5) The diamond-containing sensor section can also be entirely formed of electrically insulating components. Therefore, even if discharge occurs in a high-voltage environment where the sensor section is located, damage to the sensor section can be suppressed.

[0039] (6) The sensor unit can also be placed in an environment that can generate a voltage difference of 200V or more. Therefore, even if a discharge occurs in a voltage environment of 200V or more, the sensor unit can be protected from damage.

[0040] (7) The sensor unit can also be placed in an environment that can generate a voltage difference of 600V or more. Therefore, even if a discharge occurs in a high voltage environment of 600V or more, the sensor unit can be protected from damage.

[0041] (8) The sensor unit can also be placed in an environment that can generate a voltage difference of 1100V or more. Therefore, even if a discharge occurs in a high voltage environment of 1100V or more, the sensor unit can be protected from damage.

[0042] (9) The sensor unit can be placed in an environment where the magnetic force or magnetic field sensed by the detection unit includes frequency components below 1 kHz. Thus, it is possible to detect magnetic fields that change in an instantaneous pulse shape, and to detect anomalies such as partial discharge.

[0043] (10) The sensor unit can also be installed in an environment where the magnetic force or magnetic field sensed by the detection unit includes frequency components below 100 Hz. Thus, in power transmission equipment, etc., the alternating magnetic field generated by power transmission can be used as the detection object, and abnormalities in power transmission equipment, etc. can be detected.

[0044] (11) The diamond magnetic sensor unit may further include an application section, which, together with the excitation light irradiated onto the diamond by the excitation light irradiation section, applies alternating magnetic force, magnetic field, potential and electric field in a time-series combination. Thus, the magnetic field can be detected with good accuracy.

[0045] (12) The spin coherence time of diamond can also be less than 50 μsec. As a result, the NV center recovers rapidly from the excited state to its original state, thus enabling efficient detection of alternating magnetic and electric fields. In particular, it can detect pulsed magnetic and electric fields.

[0046] (13) The total hydrogen concentration in diamond can be greater than 0 ppm and less than 10 ppm. As a result, the spin coherence time T2 of diamond can be shortened, and the NV center can quickly recover from the excited state to the original state, thus enabling efficient detection of alternating magnetic and electric fields.

[0047] (14) The total hydrogen concentration in diamond can also be greater than 0 ppm and less than 1 ppm. This allows for the suppression of electrons from NV. - The center moves towards the hydrogen side and no longer functions as a center (becoming an NV). 0 Furthermore, the spin coherence time T2 of diamond is appropriately shortened. The NV center rapidly recovers from the excited state to its original state, thus not reducing the detection sensitivity and enabling efficient detection of alternating magnetic and electric fields.

[0048] (15) NVH in diamond - The concentrations of CH and CH2 can all be greater than 0 ppm and less than 10 ppm. This shortens the spin coherence time T2 of diamond, allowing the NV center to rapidly recover from the excited state to its original state. Therefore, it can efficiently detect alternating magnetic and electric fields, including pulsed magnetic and electric fields.

[0049] (16) NVH in diamond - The concentrations of CH, CH2, and NV can all be greater than 0 ppm and less than 1 ppm. This allows for the suppression of electrons from NV. - The center shifts towards the hydrogen side and no longer acts as an NV. - The center performs functions (becomes NV) 0Furthermore, the spin coherence time T2 of diamond is appropriately shortened. The NV center rapidly recovers from the excited state to its original state, thus not reducing the detection sensitivity, including pulse-changing magnetic and electric fields, enabling efficient detection of alternating magnetic and electric fields.

[0050] (17) The diamond magnetic sensor system according to the second aspect of this disclosure includes: the diamond magnetic sensor unit described above; an application unit; and a control unit that controls the excitation light irradiation unit, the detection unit, and the application unit. The control unit applies alternating magnetic force, magnetic field, potential, and electric field to the diamond along with the excitation light through the application unit in a time-varying manner. As a result, it is not damaged in a high-voltage environment and can detect magnetic fields with good accuracy.

[0051] [Details of the embodiments of this disclosure]

[0052] In the following embodiments, the same reference numerals are used to refer to the same parts. Their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated.

[0053] (First Implementation)

[0054] Reference Figure 2 The diamond magnetic sensor unit 100 according to the first embodiment of this disclosure includes an excitation light generating unit 106, a fluorescence reflection filter 110, an optical waveguide 112, a sensor unit 120, an LPF 122, and a light receiving unit 128. A control unit 142 is disposed outside the diamond magnetic sensor unit 100.

[0055] The control unit 142 includes a CPU (Central Processing Unit) and a storage unit (neither shown). The processing performed by the control unit 142, which will be described later, is achieved by the CPU reading and executing programs pre-stored in the storage unit.

[0056] The excitation light generating unit 106 includes a light-emitting element 102 and a light-concentrating element 104. The light-emitting element 102 is controlled by the control unit 142 to generate NV light for exciting the diamond (described later). - The excitation light from the center (hereinafter referred to as the NV center). Figure 2In the diagram, the optical path of the excitation light is represented by a dotted line. The control unit 142, for example, supplies a voltage to the light-emitting element 102 at a predetermined timing. The excitation light is green light (i.e., wavelength approximately 490–560 nm). The excitation light is preferably a laser, and the light-emitting element 102 is preferably a semiconductor laser (e.g., emitting light with a wavelength of 532 nm). The focusing element 104 focuses the excitation light output from the light-emitting element 102. The focusing element 104 is a component used to input as much of the excitation light diffused and output from the light-emitting element 102 as possible into the incident end of the optical waveguide 112, described later. The focusing element 104 preferably outputs parallel light focused within a range smaller than the size of the incident end of the optical waveguide 112 (e.g., its core diameter (i.e., the diameter of the fiber core) in the case of using an optical fiber).

[0057] The fluorescence reflection filter 110 is an element used to separate the excitation light incident from the focusing element 104 from the light emitted from the diamond (i.e., fluorescence), as described later. For example, the fluorescence reflection filter 110 is a short-pass filter that allows light with wavelengths below a specified wavelength to pass through and blocks (i.e. reflects) light with wavelengths higher than the specified wavelength, or a band-pass filter that allows light with wavelengths within a specified wavelength range to pass through and blocks (i.e. reflects) light with wavelengths outside the specified wavelength range. Generally, since the wavelength of the excitation light is shorter than that of the fluorescence, such a structure is preferred. The fluorescence reflection filter 110 is preferably a dichroic mirror with this function.

[0058] The optical waveguide 112 includes a medium for transmitting light, enabling bidirectional light transmission. Specifically, it transmits excitation light incident on the first end disposed on the excitation light generating section 106 to the second end disposed on the sensor section 120. Additionally, it transmits emitted light (i.e., fluorescence) incident on the diamond element 116 at 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 light diffused and emitted from the light source (i.e., the light-emitting element) into the optical fiber decreases. Therefore, an appropriate core diameter exists. For example, the core diameter of the optical fiber is approximately 80 μm or less and 1 μm or more.

[0059] The sensor unit 120 includes a focusing element 114 and a diamond element 116. The diamond element 116 includes an NV center. The focusing element 114 is disposed in contact with the diamond element 116. The focusing element 114 focuses the excitation light output from the optical waveguide 112 and irradiates 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 time interval. After a predetermined time (t2) has elapsed since the output of the excitation light, the control unit 142 receives the output signal of the light detection unit 126 for a predetermined time (t3) at a predetermined time interval and stores it in the storage unit.

[0060] The NV center has a structure similar to that of a diamond crystal, where carbon (C) atoms are replaced by nitrogen (N) atoms, and there are no adjacent carbon atoms (i.e., vacancies (V)). The NV center is in a state where it has captured one electron (i.e., NV...). - Under these conditions, the magnetic quantum number m is formed. s The spin triplet state is -1, 0, +1. In the absence of an external magnetic field, such as... Figure 3A As shown, m s The energy level degeneracy of the state = ±1 (represented by two line segments for convenience). In the presence of an external magnetic field, such as... Figure 3B As shown, m s The energy levels of the ±1 state split according to the magnetic field strength (Zeeman splitting). The NV center migrates from the ground state E1, maintaining its spin, to the excited state E2 through green light (e.g., a 532 nm laser) with a wavelength of approximately 490–560 nm, for example, by emitting light from the intermediate state E3, and then returns to the ground state E1. At this time, it emits red light with a wavelength of approximately 630–800 nm.

[0061] In existing methods using microwaves, approximately 2.87 GHz of microwaves are irradiated toward the center of the NV, causing m s The state transitions from 0 to m s After reaching a state of ±1 (i.e., electron spin resonance), the electron is excited by irradiation with green light. Consequently, the intensity of the observed emission decreases because the migration back to the ground state includes the migration of non-emission light (i.e., fluorescence). Therefore, a valley (i.e., a drop in signal) is observed in the ESR (Electron Spin Resonance) spectrum. Since the location (i.e., frequency) of the observed valley depends on the external magnetic field acting on the NV center, the magnetic field at the location of the NV center can be detected by observing the valley.

[0062] In contrast, in this disclosure, after irradiating the NV center with excitation light, the emitted light is measured without irradiating electromagnetic waves such as microwaves, and the magnetic field at the location of the NV center is detected. Specifically, the measurement is performed in the same manner as disclosed in Non-Patent Documents 1-3. In the method of detecting the magnetic field without irradiating electromagnetic waves, the characteristics of the PL or decoherence of the NV center under the influence of an external magnetic field are utilized.

[0063] For example, after irradiation with excitation light, the intensity of PL emitted from the NV center decays exponentially over time, the degree of which depends on the external magnetic field; the stronger the external magnetic field, the earlier the decay occurs. For example, the measured value of PL can be approximated using a triple exponential function related to the measurement time (see Non-Patent Document 2). Therefore, for example, regarding the diamond used, if the relationship between the external magnetic field and the degree of decay of the observed PL signal intensity is derived beforehand, the external magnetic field can be detected and the magnetic field strength determined based on the PL value measured after a predetermined time has elapsed since irradiation with excitation light. For high-precision detection of the magnetic field, microwaves are preferred, but even without microwaves, magnetic fields of approximately 10 mT to 20 mT can be detected in this manner. Here, it is preferable to align the crystal orientation of the diamond with the {100} direction relative to the direction of the external field, such as the external magnetic field being measured. In this way, based on the sp... 3 Bonding (based on sp) 3 The bonding of hybrid orbitals enables all NV centers formed in four directions to sense the external field isotropically, resulting in the highest contrast (i.e., the signal-to-signal ratio). If the direction deviates, for example, if the direction of the NV center is orthogonal to the magnetic field, the NV center loses its magnetic sensitivity. Therefore, only the non-orthogonal NV centers in the four directions have contrast, leading to a decrease in the sensitivity of the sensor.

[0064] It should be noted that a property known as GSLAC (ground-state level anti-crossing) can also be used (see Non-Patent Literature 1). That is, an external magnetic field of approximately 102.4 mT causes degeneracy and mixing of Zeeman sublevels at the NV center (i.e., anti-crossing), which can be observed as a decrease in fluorescence intensity under photoexcitation. In other words, if the NV center is under certain magnetic fields, the fluorescence at the NV center changes, and this change can be measured. When using this method, two electromagnets are required to apply the static magnetic field and the perturbation magnetic field. For example, an electromagnet (e.g., an air-core coil) is set up to apply a scanning magnetic field (e.g., changing from 0 to 120 mT over 5 seconds) to the NV center and an electromagnet to apply a small perturbation magnetic field (e.g., an amplitude of approximately 0.1 mT and a frequency of 100 kHz). The process is repeated as follows: while applying a scanning magnetic field to the diamond and applying a perturbation magnetic field using a local oscillator with a lock-in amplifier, excitation light is irradiated, and the PL is detected using a lock-in amplifier. Therefore, if the magnetic field at the location of the NV center (i.e., the combined magnetic field of the scanning magnetic field and the external magnetic field of the object being tested) is approximately 102.4 mT, GSLAC is observed in the PL measurement signal, thus the external magnetic field of the object being tested can be detected using the scanning magnetic field at this time. Additionally, a valley in the PL measurement signal observed around 51.4 mT can also be detected. This valley is based on the cross-relaxation between the NV center and its surrounding P1 center (a single substituted nitrogen as an electron donor). The external magnetic field of the object being tested can be detected using the scanning magnetic field at this time.

[0065] Alternatively, a method can be used to detect the valley of the T1 relaxation time (longitudinal relaxation time) based on the cross-relaxation of the NV center and the surrounding P1 center, observed around 512 G (51.2 mT) (see Non-Patent Document 3). In this case, an electromagnet for applying a scanning magnetic field to the diamond is also required.

[0066] The specific PL measurement is performed as follows. That is, the light diffused and emitted from the diamond element 116 (i.e., fluorescence) is focused by the focusing element 114 and input as parallel light to the second end of the optical waveguide 112. Figure 2In the diagram, the optical path of the emitted light is represented by a dashed line. Light (i.e., fluorescence) input into the optical waveguide 112 is transmitted through the waveguide 112 and output from its first end. 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, and is focused by the focusing element 124 before being incident on the photodetector 126. The light affected by the magnetic field at the location where the diamond element 116 is disposed is detected by the photodetector 126. The photodetector 126 generates and outputs an electrical signal corresponding to the incident light. The photodetector 126 is, for example, a photodiode. The output signal of the photodetector 126 is acquired by the control unit 142.

[0067] LPF122 is a long-pass filter that allows light with wavelengths above a specified wavelength to pass through while blocking (e.g., reflecting) light with wavelengths smaller than the specified wavelength. The emitted light from the diamond element 116 is red light, which passes through LPF122, but the excitation light, due to its shorter wavelength, does not pass through LPF122. Therefore, it is possible to suppress the excitation light emitted from the light-emitting element 102 from being detected by the photodetector 126 and becoming noise, thus suppressing the decrease in detection sensitivity of the emitted light (i.e., fluorescence) from the diamond element 116.

[0068] Based on the above, the control unit 142 can irradiate excitation light onto the diamond element 116 and acquire the light (i.e., fluorescence) emitted from the diamond element 116 as an electrical signal output from the photodetector 126. The magnetic field strength at the location of the diamond element 116 can be calculated based on the observed emitted light. That is, the diamond magnetic sensor unit 100 functions as a magnetic sensor. It should be noted that the diamond magnetic sensor unit 100 is not limited to magnetic fields; it can also be used as a sensor for detecting physical quantities related to magnetic fields, such as magnetization, electric field, voltage, current, temperature, and pressure.

[0069] The sensor unit 120 does not include conductive components that propagate electromagnetic waves, such as microwave irradiation coils. The diamond element 116 and the focusing element 114, which form the main body of the sensor, are formed of electrically insulating materials. That is, the entire sensor unit 120 is formed of electrically insulating materials. Therefore, even in high-voltage environments, the sensor unit itself will not be damaged by partial discharge or the like, and can detect magnetic fields with good accuracy.

[0070] If an optical fiber is used in the optical waveguide 112, even if the sensor unit 120 and the second end of the optical waveguide 112 are located in a high-voltage device, the effects of partial discharge on the excitation light generating unit 106 and the light receiving unit 128 can be avoided. Furthermore, by positioning the excitation light generating unit 106 and the light receiving unit 128 away from the high-voltage environment via the optical waveguide 112, the diamond magnetic sensor unit 100 can remotely measure magnetic fields, etc. Additionally, the sensor unit 120 includes a focusing element 114 disposed between the diamond element 116 and the optical waveguide 112, thus reducing the loss of excitation and emission light and improving detection accuracy. Furthermore, by providing a fluorescence reflection filter 110 that separates the excitation and emission light, and transmitting the excitation and emission light through a single medium (e.g., the optical waveguide 112), as described later, compared to the case where two separate media are used to transmit the excitation and emission light, fewer components can be incorporated, resulting in a simpler structure.

[0071] It should be noted that the diamond magnetic sensor unit 100 may also include a conductive component that propagates electromagnetic waves that affect the NV center of the diamond. When a conductive component is included, it is preferable that the conductive component be spaced at least 10 mm from the sensor section 120. This allows for accurate detection of the magnetic field. More preferably, the conductive component is spaced at least 50 mm from the sensor section 120. This improves detection accuracy. Even more preferably, the conductive component is spaced at least 100 mm. This further improves detection accuracy. It should be noted that since the actual dimensions of the lens holder, fiber optic plug, and socket are approximately 10 mm, a spacing of less than 10 mm may result in uneven electromagnetic field distribution. This could potentially lead to insulation failure or equipment malfunctions such as arcing from the transmission line during rapid potential changes like lightning strikes.

[0072] The sensor unit can be installed, for example, in or around equipment that typically generates a voltage difference of 200V or more (such as transformers or solar power generation equipment). Hereinafter, the equipment and its surroundings (i.e., the area within a specified range of the equipment) will be collectively referred to as the "environment." Alternatively, the sensor unit can also be installed in environments that typically generate a voltage difference of 600V or 1100V or more (such as power distribution equipment, high-voltage transmission lines, distribution lines, or wind power generation equipment). In such environments, even if discharge occurs, the sensor unit can avoid damage and can detect magnetic fields with high accuracy.

[0073] (Second Implementation)

[0074] In the first embodiment, a single optical waveguide 112 is used for bidirectional light transmission (i.e., excitation light and emission light), but in the second embodiment, optical waveguides are used to transmit the excitation light and emission light of the diamond element 116 respectively. (Refer to...) Figure 4 The diamond magnetic sensor unit 200 according to the second embodiment of this disclosure includes an excitation light generating unit 206, a first optical waveguide 212, a focusing element 208, a fluorescence reflection filter 210, a sensor unit 220, an LPF 222, a focusing element 224, a second optical waveguide 230, and a light receiving unit 228. Similar to the first embodiment, a control unit 142 is disposed externally on the diamond magnetic sensor unit 200.

[0075] The excitation light generating unit 206 includes a light-emitting element 202 and a light-concentrating element 204. The sensor unit 220 includes a light-concentrating element 214 and a diamond element 216. The light-receiving unit 228 includes a light detection unit 226. The light-emitting element 202, the light-concentrating element 204, the fluorescence reflection filter 210, the light-concentrating element 214, the diamond element 216, the LPF 222, and the light detection unit 226 are respectively connected to… Figure 2 The light-emitting element 102, focusing element 104, fluorescence reflection filter 110, focusing element 114, diamond element 116, LPF 122, and photodetector 126 shown correspond to each other and function similarly. Therefore, they will be described briefly. Figure 4 In, with Figure 2 Similarly, dotted lines represent the light path of excitation light, and dashed lines represent the light path of emission light.

[0076] Similar to the first embodiment, the light-emitting element 202 is controlled by the control unit 142 to generate excitation light for exciting the NV center of the diamond. The control unit 142, for example, supplies a voltage to the light-emitting element 202 at a predetermined timing. The excitation light is green light. The excitation light is preferably a laser, and the light-emitting element 202 is preferably a semiconductor laser. The focusing element 204 focuses the excitation light diffused and output from the light-emitting element 202 and inputs it to the incident end of the first optical waveguide 212.

[0077] The first optical waveguide 212 includes a medium for transmitting light. The first optical waveguide 212 and... Figure 2 Unlike the waveguide 112 shown, this waveguide transmits excitation light but not the emitted light from the diamond element 216. That is, the excitation light incident on the first waveguide 212 at the incident end located on the side of the excitation light generation section 206 is transmitted to the output end located on the side of the sensor section 220 and output. The first waveguide 212 is, for example, an optical fiber. The excitation light diffused and output from the first waveguide 212 is focused by the focusing element 208 and incident as parallel light onto the fluorescence reflection filter 210.

[0078] The fluorescence reflection filter 210 is a component used to separate the excitation light incident from the focusing element 208 from the light emitted from the diamond element 216 (i.e., fluorescence). The fluorescence reflection filter 210 can also be a dichroic mirror.

[0079] The focusing element 214 focuses the excitation light input through the fluorescence reflection filter 210 and irradiates the diamond element 216. The focusing 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 excitation light is controlled by the control unit 142. Thus, as described above, red light (i.e., fluorescence) is emitted from the diamond element 216.

[0080] The light diffused and emitted from the diamond element 216 (i.e., red fluorescence) is focused into parallel light by the focusing element 214 and incident on 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 incident on the LPF 222. The emitted light (i.e., red fluorescence) from the diamond element 216 incident on the LPF 222 passes through the LPF 222, is focused by the focusing element 224, and incident on the incident end of the second optical waveguide 230. The LPF 222 suppresses the excitation light emitted from the light-emitting element 202 from being detected by the photodetector 226 as noise, thus reducing the detection sensitivity of the emitted light (i.e., fluorescence) from the diamond element 216.

[0081] The second optical waveguide 230 includes a medium for transmitting light. The second optical waveguide 230 transmits light incident from the focusing element 224 to the incident end (i.e., the emitted light from the diamond element 216) to the output end disposed on the light-receiving side of the light-receiving portion 228. The light output from the second optical waveguide 230 is detected by a 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.

[0082] Based on the above, similar to the first embodiment, the control unit 142 can irradiate excitation light onto the diamond element 216 and acquire the light (i.e., fluorescence) emitted from the diamond element 216 as an electrical signal output from the photodetector 226. Therefore, the diamond magnetic sensor unit 200 functions as a magnetic sensor. The diamond magnetic sensor unit 200 is not limited to magnetic fields, and can also be used as a sensor for detecting physical quantities related to magnetic fields, such as magnetization, electric field, voltage, current, temperature, and pressure.

[0083] The sensor unit 220 does not include conductive components that propagate electromagnetic waves, such as microwave irradiation coils. The diamond element 216 and the focusing element 214, which form the main body of the sensor, are formed of electrically insulating materials. That is, the entire sensor unit 220 is formed of electrically insulating materials. Therefore, even in high-voltage environments, the sensor unit itself will not be damaged by partial discharge or the like, and can detect magnetic fields with good accuracy.

[0084] If optical fibers are used in both optical waveguides (i.e., the first optical waveguide 212 and the second optical waveguide 230), even if the sensor unit 220 is installed in a high-voltage device, the effects of partial discharge on the excitation light generating unit 206 and the light receiving unit 228 can be avoided. Furthermore, by positioning the excitation light generating unit 206 and the light receiving unit 228 away from the high-voltage environment via the first optical waveguide 212 and the second optical waveguide 230, the diamond magnetic sensor unit 200 can remotely measure magnetic fields, etc. Additionally, the sensor unit 220 includes a focusing element 214 disposed between the diamond element 216 and the first optical waveguide 212 and the second optical waveguide 230, thereby reducing the loss of excitation and emitted light and improving detection accuracy.

[0085] By using two optical waveguides (i.e., the first optical waveguide 212 and the second optical waveguide 230), excitation light and the emitted light from the diamond element 216 with different wavelengths can be transmitted appropriately, respectively. That is, by using optical fibers with core diameters corresponding to the wavelengths, suitable focusing optical systems (i.e., focusing elements 204, 208, 214, and 224) can be designed, improving light transmission efficiency and detection accuracy. When using optical fibers in the waveguides, the core diameter of the fiber transmitting the emitted light from the diamond (i.e., the second optical waveguide 230) is preferably larger than the core diameter of the fiber transmitting the excitation light (i.e., the first optical waveguide 212).

[0086] As described above, to increase the energy density of the excitation light, a smaller core diameter is preferable for the optical fiber used to transmit the excitation light. However, if the core diameter is too small, losses will occur when light is input from the light source into the optical fiber. Therefore, an appropriate core diameter is required. The core diameter of the first optical waveguide 212 is preferably 1 μm or more and 100 μm or less. On the other hand, a larger core diameter is preferable for the optical fiber used to transmit the emitted light from the diamond element 216. 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.

[0087] (First variation)

[0088] In the second embodiment, a fluorescence reflection filter 210 is used to separate the excitation light from the emitted light of the diamond element 216, but this is not a limitation. An LPF can also be used to separate the excitation light from the emitted light of the diamond element 216.

[0089] Reference Figure 5 In the first modified example, the diamond magnetic sensor unit 300 uses an LPF 302 to separate the excitation light from the light-emitting element 202 from the emitted light from the diamond element 216. The diamond magnetic sensor unit 300 is located in the diamond magnetic sensor unit 200 (refer to...). Figure 4In this process, the fluorescence reflection filter 210 is replaced with an LPF302, and the path for generating and transmitting the excitation light is replaced with the path for transmitting and detecting the emitted light from the diamond element 216. The LPF302 is a long-pass filter. Figure 5 In the middle, it is marked with Figure 4 The same reference numerals indicate the constituent elements as... Figure 4 They are the same. Therefore, there is no need to repeat the descriptions of them. It should be noted that in Figure 5 In, with Figure 4 Similarly, dotted lines represent the light path of excitation light, and dashed lines represent the light path of emission light.

[0090] The excitation light generated by the light-emitting element 202 is focused by the focusing 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, focused by the focusing element 224 to become parallel light, and incident on the LPF 302. Since the excitation light is green light, it is reflected by the LPF 302 and incident on the focusing element 214.

[0091] On the other hand, the emitted light from the diamond element 216 is focused into parallel light by the focusing element 214 and incident on the LPF 302. The emitted light (i.e., red fluorescence) from the diamond element 216 is focused by the focusing element 224 through the LPF 302 and incident on the second optical waveguide 230, transmitted through the second optical waveguide 230 to the light-receiving unit 228, and 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 for detecting magnetic fields, etc.

[0092] (Second variation)

[0093] The above description focuses on the case where excitation light is incident on one surface of a diamond element including the NV center, and the emitted light from that same surface is measured; however, it is not a limitation. When the diamond element including the NV center has multiple flat surfaces, the surface irradiating the excitation light and the surface measuring the emitted light may differ. A flat surface refers to a plane with a defined or greater area; here, a flat surface of the diamond element including the NV center refers to a plane with an area larger than that of a circle with a diameter of approximately 200 μm.

[0094] Reference Figure 6 The diamond magnetic sensor unit 400 involved in the second modification detects light emitted from a surface different from the surface on which the excitation light is incident on the diamond element 402. The diamond magnetic sensor unit 400 in... Figure 4In the diamond magnetic sensor unit 200 shown, sensor unit 220 is replaced by sensor unit 408, and focusing element 208, fluorescence reflection filter 210, and focusing element 224 are removed. Figure 6 In the middle, it is marked with Figure 4 The same reference numerals indicate the constituent elements as... Figure 4 Same. No repetition of their descriptions. In Figure 6 In, with Figure 4 Similarly, dotted lines represent the light path of excitation light, and dashed lines represent the light path of emission light.

[0095] The sensor unit 408 includes a diamond element 402, a focusing element 404, and a focusing element 406. The diamond element 402 includes an NV center and has multiple flat surfaces. The diamond element 402 is, for example, formed as a cuboid. The focusing element 404 is disposed in contact with one flat surface of the diamond element 402 (hereinafter referred to as the first flat surface). The focusing element 406 is disposed in contact with a flat surface of the diamond element 402 that is different from the first flat surface (hereinafter referred to as the second flat surface).

[0096] Excitation light transmitted by the first optical waveguide 212 is incident on the focusing element 404 and focused by the focusing element 404 to irradiate the first flat surface of the diamond element 402. As described above, by irradiating the diamond element 402 with excitation light at a predetermined time, light is 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, incident on the LPF 222, and then incident on the incident end of the second optical waveguide 230 through the LPF 222. Then, the light emitted from the second flat surface of the diamond element 402 (i.e., red fluorescence) is transmitted by the second optical waveguide 230 to the light detection unit 226 and detected by the light 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 and the like.

[0097] By configuring the structure to detect emitted light from a surface different from the surface irradiating the excitation light (i.e., the second flat surface), the number of focusing elements can be reduced, as can the elements used to separate the excitation light from the emitted light of the diamond element (e.g., fluorescence reflection filters). Therefore, the diamond magnetic sensor unit can be configured with a simpler structure, thus reducing costs.

[0098] In the above description, the case where the diamond element 402 is formed as a cuboid and the first and second flat surfaces are two faces forming a 90-degree angle has been explained, but it is not limited to this. When the diamond element 402 is formed as a cuboid, the flat surface parallel to the first flat surface can also be used as the second flat surface to focus the emitted light from the object being detected. Furthermore, the diamond element 402 only needs to have at least two flat surfaces and is not limited to a hexahedron; the shape of the diamond element 402 is arbitrary.

[0099] (Third variation)

[0100] The above description addresses the case where the sensor unit includes a focusing element, but it is not limited to this. (See reference...) Figure 7 The diamond magnetic sensor unit 500 involved in the third variation is from Figure 2 The diamond magnetic sensor unit 100 shown omits the focusing element 114. That is, the sensor section 502 includes a diamond element 116 but does not include the focusing element. The diamond element 116 is configured to contact the second end of the optical waveguide 112.

[0101] In the diamond magnetic sensor unit 500, compared with the diamond magnetic sensor unit 100 (reference 100) Figure 2 Similarly, if the diamond element 116 is irradiated with excitation light (i.e., green light) output from the light-emitting element 102, the NV center of the diamond element 116 is excited, emitting light (i.e., red fluorescence) and returning to its original state. Therefore, by measuring the emitted light, the diamond magnetic sensor unit 500 functions as a magnetic sensor. The method for measuring the magnetic field is the same as in the first embodiment.

[0102] The sensor unit 502 does not include conductive components such as coils; it is entirely composed of electrically insulating components. Therefore, even if the sensor unit 502 is installed in a high-voltage device, it will not be damaged by discharge or the like, and can safely measure magnetic fields in high-voltage environments.

[0103] (Fourth variation)

[0104] In the first and second embodiments, the case where a medium for transmitting light is used to construct an optical waveguide for transmitting excitation light and the emitted light of the diamond element has been described, but the invention is not limited to this. The diamond magnetic sensor unit involved in the fourth variation uses a mirror to construct the optical waveguide. Specifically, refer to... Figure 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. Similar to the first embodiment, a control unit 142 is disposed outside the diamond magnetic sensor unit 600.

[0105] The excitation light generating unit 106 includes a light-emitting element 102 and a light-concentrating element 104. The sensor unit 120 includes a light-concentrating element 114 and a diamond element 116. The light receiving unit 128 includes a light detection unit 126. Figure 8 In the middle, it is marked with Figure 2 The same reference numerals indicate the constituent elements as... Figure 2 They are the same. Therefore, we will not repeat the descriptions of them.

[0106] The concave mirror 602 is formed by cutting a sphere with radius r1 centered at point O along a plane. The end (cut-off portion) of the concave mirror 602 is a circle with diameter d1. An opening 606 for allowing excitation light from the excitation light generating section 106 to pass through and an opening 608 for allowing emitted light to pass through are formed on the concave mirror 602. Openings 606 and 608 are, for example, circular. Of the two curved surfaces (i.e., parts of the sphere) that are the two faces of the concave mirror 602, the curved surface opposite to the convex mirror 604 becomes the reflecting surface of the emitted light (hereinafter referred to as the mirror surface). The convex mirror 604 is formed by cutting a sphere with radius r2 centered at point O along a plane. The end (cut-off portion) of the convex mirror 604 is a circle with diameter d2. Of the two curved surfaces (i.e., parts of the sphere) that are the two faces of the convex mirror 604, the curved surface opposite to the concave mirror 602 becomes the mirror surface.

[0107] exist Figure 8 In, with Figure 2 Similarly, the light path of the excitation light is represented by dotted lines, and the light path of the emitted light is represented by dashed lines. The excitation light generated by the light-emitting element 102 is focused by the focusing element 104 to become parallel light, which propagates in space and is incident on the focusing element 114, where it is focused and illuminates the diamond element 116. That is, the space acts as an optical waveguide for the excitation light, and the space constitutes an optical waveguide for the excitation light. On the other hand, the emitted light from the diamond element 116 is reflected in sequence by the concave mirror 602 and the convex mirror 604, and is incident on the light-receiving part 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. Thus, similar to 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.

[0108] It should be noted that, in the above description, the center of both the concave mirror 602 and the convex mirror 604 is located at point O, but the centers of the concave mirror 602 and the convex mirror 604 can also be located at different positions. Furthermore, the description also mentions that the ends of both the concave mirror 602 and the convex mirror 604 are circular (i.e., a shape formed by cutting a sphere with a plane), but this is not a limitation. The opposing surfaces of the concave mirror 602 and the convex mirror 604 only need to be mirror surfaces, and the shapes of the ends of the concave mirror 602 and the convex mirror 604 are arbitrary.

[0109] Second implementation method (refer to) Figure 4 ), First variant (refer to) Figure 5 ) and the second variation (see Figure 6 The text describes the case where excitation light is transmitted via optical waveguide 212 such as an optical fiber, but it is not limited to this. For example, the diamond magnetic sensor unit 200 (see reference...) Figure 4 ) and diamond magnetic sensor unit 300 (refer to Figure 5 The light waveguide 212 and the focusing element 208 may also be omitted. The excitation light output from the light-emitting element 202 is focused into parallel light by the focusing element 204, therefore the focusing element 208 may also be absent. The excitation light focused by the focusing element 204 is transmitted through space itself and incident on the fluorescence reflection filter 210 or LPF 302. Similarly, the diamond magnetic sensor unit 400 (see reference...) Figure 6 It may also be without an optical waveguide 212. The excitation light focused by the focusing element 204 is transmitted by space itself and incident on the focusing element 404.

[0110] The above description focuses on the use of diamond elements with NV centers in diamond magnetic sensor units, but it is not a limitation. Any diamond element with a color center possessing electron spin can be used. A color center with electron spin is a center that forms a spin triplet state and emits light upon excitation; NV centers are representative examples. In addition, color centers with electron spin are known to 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 types can be used instead of diamond elements with NV centers to construct the diamond magnetic sensor unit.

[0111] The excitation light is preferably a laser, and a semiconductor laser is more preferred as the generating device due to its miniaturization capability. The detector for the emitted light from the diamond element can also be a vacuum tube type, but a semiconductor detection device is more preferred for miniaturization.

[0112] The optical waveguide is preferably a coaxial structure with two or more layers, having a core portion through which light passes and portions of a material with a different refractive index formed around the core portion. The core portion may not be tightly filled with the light-transmitting medium. Since space itself can transmit light, the core portion can also be a cavity. The optical waveguide is preferably made of optical fiber with a core diameter of 1 μm or more and 80 μm or less. This is because using optical fiber makes it easier to guide the laser to the desired location and suppresses divergence at the output end of the fiber.

[0113] The focusing element can be formed of any material that has the function of focusing light. For example, it can be a lens formed from a silicon oxide-based raw material (e.g., glass; additives other than silicon oxide may also be included), or it can be a material with diffraction properties. The focusing element is preferably a lens that transmits light and utilizes the refraction phenomenon. Spherical lenses, hemispherical lenses, and Fresnel lenses are preferred. In particular, due to the relationship between the refractive index and the shape of a sphere, a lens in which the focal point of parallel light is located on the spherical surface is more preferred. This is because if such a lens is used, the adjustment of the optical focus and optical axis becomes very simple, and the amount of light can be utilized to the maximum extent.

[0114] When the sensor unit is placed in a high-voltage environment, the optical waveguide (e.g., optical fiber) that transmits the excitation light and the emitted light from the diamond is preferably arranged through an insulating barrier. This isolates the excitation light generating unit and the light receiving unit from the high voltage, protecting the components used in the excitation light generating unit and the light receiving unit.

[0115] When using the aforementioned diamond magnetic sensor unit to detect time changes in magnetic fields, etc., based on alternating current, it is preferable that the NV center of the diamond element rapidly recovers from its emitted light state to its original state (i.e., the state before excitation) after being excited. Therefore, a short spin coherence time T2 of the diamond element is preferable. For example, the spin coherence time T2 of the diamond element is preferably less than 50 μsec. This allows the NV center to rapidly recover from the excited state to its original state, thus enabling efficient detection of alternating magnetic and electric fields. In particular, it is possible to detect pulsed magnetic and electric fields. It should be noted that the detection sensitivity is related to (T2). -1 / 2 The difference is proportional, therefore the smaller T2 is, the lower the detection sensitivity. Therefore, when detecting rapid changes in the magnetic field, such as pulsed magnetic field changes, it is advisable to sacrifice detection sensitivity and shorten the spin coherence time T2 of the diamond element as much as possible.

[0116] To shorten the spin coherence time, it is preferable that the diamond element includes impurities. Considering that a smaller T2 results in lower detection sensitivity, for example, the total hydrogen concentration in the diamond is preferably greater than 0 ppm and less than 10 ppm. Here, concentration (ppm unit) represents the proportion of atoms. This shortens the spin coherence time T2 of the diamond, and since the NV center rapidly recovers from the excited state to its original state, it can efficiently detect alternating magnetic and electric fields. However, if the concentration of hydrogen atoms in the diamond increases, the NV... - Electrons on the central side move towards the hydrogen side and no longer function as a color center (i.e., they become NV centers). 0 Therefore, the total hydrogen concentration in diamond is more preferably greater than 0 ppm and less than 1 ppm. This allows for the suppression of electrons from NV. -The center moves toward the hydrogen side and no longer functions as the center, and the spin coherence time T2 of diamond is appropriately shortened.

[0117] In addition, NVH in diamond - The concentrations of hydrogen atoms, CH, and CH2 are preferably greater than 0 ppm and less than 10 ppm, respectively. This shortens the spin coherence time T2 of diamond, allowing the NV center to rapidly recover from the excited state to its original state, thus enabling efficient detection of alternating magnetic and electric fields. As described above, to suppress the concentration of hydrogen atoms in diamond, the NVH concentration in diamond... - The concentrations of CH, CH2, and CH3 are more preferably greater than 0 ppm and less than 1 ppm. This allows for the suppression of NV. - Electrons on the central side move toward the hydrogen side and no longer function as color centers, thus appropriately shortening the spin coherence time T2 of diamond.

[0118] By using diamond with a short spin coherence time, a diamond magnetic sensor unit can be placed in an environment where the magnetic or magnetic force includes frequency components below 100 Hz to detect magnetic or magnetic forces. For example, in power distribution equipment, the alternating magnetic field generated by power transmission can be used as the detection target to detect anomalies in such equipment. Furthermore, by using diamond with a short spin coherence time, a diamond magnetic sensor unit can be placed in an environment where the magnetic or magnetic force includes frequency components below 1 kHz to detect magnetic or magnetic forces. For example, it can detect instantaneously pulsed magnetic fields and anomalies such as partial discharge.

[0119] The above description describes the detection of emitted light from a diamond by irradiating it with excitation light without irradiating electromagnetic waves, but it is not limited to this. It is also possible to detect emitted light from a diamond by applying alternating magnetic force, magnetic field, potential, and electric field in a time-varying manner along with the irradiation of the diamond with excitation light. In this case, the diamond magnetic sensor unit includes an application device (e.g., an electromagnet) for combining alternating magnetic force, magnetic field, potential, and electric field in a time-varying manner. This allows for the detection of magnetic fields with high accuracy.

[0120] (Structure of the embodiment)

[0121] Figure 4 Implementation of the structure shown is as follows: Figure 9 As shown. Figure 9 This diagram illustrates a configuration where a focusing element 214 and a diamond element 216 constituting the sensor section are positioned near an electrical wiring 260, allowing an alternating current (e.g., 50Hz or 60Hz, 30A) to flow through the electrical wiring 260, and using the resulting fluctuating magnetic field as the detection target. Figure 9In, with Figure 4 The constituent elements shown are labeled with the corresponding constituent elements. Figure 4 Same reference numerals as shown in the attached figures.

[0122] The first optical waveguide 212 and the second optical waveguide 230 are, for example, step-index multi-model optical fibers. The first optical waveguide 212 has, for example, a core diameter of 50 μm and a numerical aperture (NA) of 0.2. The second optical waveguide 230 has, for example, a core diameter of 400 μm and an NA of 0.5. A rectangular diamond of, for example, 3 mm × 3 mm × 0.3 mm is used in the diamond element 216. A spherical lens of, for example, 2 mm in diameter is used in the focusing element 214, which is fixed in contact with the surface of the diamond element 216 (for example, a flat surface of 3 mm × 3 mm). In the optical system for transmitting excitation light, in addition to the focusing element 208 and the fluorescence reflection filter 210, a triangular prism 250 is also configured to form a collimating optical system. The collimating optical system can be adjusted so that the excitation light is incident on the center of the focusing element 214.

[0123] In the light detection unit 226 (reference) Figure 4 In this context, a PIN-AMP (i.e., a photodiode IC with a linear current amplification circuit) is used, for example. A PIN-AMP is, for example, the photodiode S7183 or S7184 (manufactured by Hamamatsu Photonics Co., Ltd.). This photodiode has a photodiode sensitivity wavelength range of 300–1000 nm, a maximum sensitivity wavelength of 650 nm, and amplifies the photocurrent generated by the photodiode by 1300 times before outputting it.

[0124] The present disclosure has been described above by way of example, but the above-described embodiments are merely examples and the present disclosure is not limited to the above-described embodiments. The scope of the present disclosure is defined by the claims, based on the detailed description of the invention, and includes all modifications within the meaning and scope equivalent to the statements therein.

[0125] Explanation of reference numerals in the attached figures

[0126] 100, 200, 300, 400, 500, 600 diamond magnetic sensor units

[0127] 102, 202 Light-emitting elements

[0128] Concentrating elements: 104, 114, 124, 204, 208, 214, 224, 404, 406

[0129] 106, 206 Excitation Light Generating Section

[0130] 110, 210 Fluorescent Reflection Filters

[0131] 112 Optical waveguide

[0132] 116, 216, 402 diamond components

[0133] Sensors 120, 220, 408, and 502

[0134] 122, 222, 302, 908 LPF

[0135] 126, 226 Optical Detection Department

[0136] Light-receiving sections 128 and 228

[0137] 142 Control Department

[0138] 212 First Optical Waveguide

[0139] 230 Second optical waveguide

[0140] 250 triangular prism

[0141] 260 Electrical wiring

[0142] 602 Concave Mirror

[0143] 604 Convex Mirror

[0144] 606, 608 opening

[0145] 912, 914, 916 base plate

[0146] 900 LED

[0147] 902 SPF

[0148] 904 diamond

[0149] 906 lens

[0150] 910 photodiode

[0151] E1, E2, E3 energy levels

[0152] O point

[0153] radius r1, r2

[0154] d1 and d2 are diameters.

Claims

1. A diamond magnetic sensor unit, comprising: The sensor unit includes a diamond with a color center, the color center having an electron spin; An excitation light irradiation section irradiates the diamond with excitation light; as well as The detection unit detects the emitted light from the color center of the diamond. The detection unit detects the emitted light generated by irradiating the diamond with excitation light by the excitation light irradiation unit without irradiating the diamond with electromagnetic waves. The diamond magnetic sensor unit does not include a conductive component for propagating the electromagnetic waves, or The diamond magnetic sensor unit includes a conductive component that propagates the electromagnetic waves, and the conductive component is disposed at a distance of more than 10 mm from the sensor unit. NVH in the diamond - The concentrations of CH, CH2, and CH2 are all greater than 0 ppm and less than 10 ppm.

2. The diamond magnetic sensor unit according to claim 1, wherein, The conductive component is positioned at a distance of 50 mm or more from the sensor portion.

3. The diamond magnetic sensor unit according to claim 1, wherein, The conductive component is disposed at a distance of more than 100 mm from the sensor part.

4. The diamond magnetic sensor unit according to any one of claims 1 to 3, wherein, It further includes an optical waveguide for transmitting the excitation light and the emitted light.

5. The diamond magnetic sensor unit according to any one of claims 1 to 3, wherein, The sensor portion containing the diamond is entirely formed of electrically insulating components.

6. The diamond magnetic sensor unit according to any one of claims 1 to 3, wherein, The sensor unit is placed in an environment capable of generating a voltage difference of 200V or more.

7. The diamond magnetic sensor unit according to any one of claims 1 to 3, wherein, The sensor unit is installed in an environment capable of generating a voltage difference of 600V or more.

8. The diamond magnetic sensor unit according to any one of claims 1 to 3, wherein, The sensor unit is installed in an environment capable of generating a voltage difference of 1100V or more.

9. The diamond magnetic sensor unit according to any one of claims 1 to 3, wherein, The sensor unit is placed in an environment where the magnetic force or magnetic field sensed by the detection unit includes frequency components below 1 kHz.

10. The diamond magnetic sensor unit according to any one of claims 1 to 3, wherein, The sensor unit is placed in an environment where the magnetic force or magnetic field sensed by the detection unit includes frequency components below 100 Hz.

11. The diamond magnetic sensor unit according to any one of claims 1 to 3, wherein, It further includes an application section that, together with the excitation light irradiating the diamond by the excitation light irradiation section, applies alternating magnetic force, magnetic field, potential and electric field in a time-varying manner.

12. The diamond magnetic sensor unit according to any one of claims 1 to 3, wherein, The spin coherence time of the diamond is less than 50 µsec.

13. The diamond magnetic sensor unit according to any one of claims 1 to 3, wherein, The total hydrogen concentration in the diamond is greater than 0 ppm and less than 10 ppm.

14. The diamond magnetic sensor unit according to any one of claims 1 to 3, wherein, The total hydrogen concentration in the diamond is greater than 0 ppm and less than 1 ppm.

15. The diamond magnetic sensor unit according to any one of claims 1 to 3, wherein, NVH in the diamond - The concentrations of CH, CH2, and CH2 are all greater than 0 ppm and less than 1 ppm.

16. A diamond magnetic sensor system, comprising: The diamond magnetic sensor unit according to claim 11; as well as The control unit controls the excitation light irradiation unit, the detection unit, and the application unit. The control unit, through the application unit, combines alternating magnetic force, magnetic field, potential and electric field in time to irradiate the diamond together with the excitation light.

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