Diamond spin sensor system

Abstract

This diamond spin sensor system includes: a sensor part that includes diamond having a color center with an electron spin; a control power supply part that generates excitation light for irradiating the sensor part; and a joint part that connects the sensor part and the control power supply part. The joint part transmits the excitation light to the sensor part and irradiates the diamond therewith, and transmits, to the control power supply part, fluorescence radiated from the diamond.

Description

Diamond Spin Sensor System

[0001] This disclosure relates to a diamond spin sensor system. This application claims priority to Japanese Application No. 2023-100677, filed on June 20, 2023, and incorporates by reference all of the contents of said Japanese application.

[0002] In power cables installed at high altitudes such as steel towers as power transmission and distribution facilities, devices equipped with temperature detectors, current detectors, etc. are installed in the power cables for the purpose of maintenance and management, abnormality detection, etc. For example, Patent Document 1 listed below discloses a configuration in which an optical sensor (utilizing the Faraday effect or the Pockels effect) is installed on the high-voltage side to detect fault locations in power transmission and distribution lines, etc., and the detected optical signal is transmitted to a monitoring and control system on the ground side via an optical fiber in an optical fiber-embedded insulator.

[0003] Furthermore, in order to eliminate the need for wires (such as optical fibers) to connect detectors installed on power cables with equipment installed on the ground, the detectors are sometimes equipped with wireless communication capabilities. That is, information such as temperature and current values ​​detected by the detectors installed on the power cables is transmitted to equipment installed on the ground via a wireless communication unit within the detectors.

[0004] A diamond spin sensor system using the NV center of diamond (i.e., NV center) is known as a sensor for detecting magnetic fields, temperature, etc. The NV center, which is formed by nitrogen occupying a substitutional position of carbon in diamond and a vacancy adjacent to the nitrogen, becomes negatively charged (this state is called NV － The NV center has a ground state in which the spin S is triplet (i.e., the spin S is S=1). When the NV center is excited with a wavelength of 532 nm (i.e., green light), it emits fluorescence with a wavelength of 637 nm (i.e., red light). The intensity of the fluorescence changes depending on the spin state, and the spin state changes due to magnetic resonance between a magnetic field applied to the NV center and microwaves or radio waves, so it can be used as a magnetic sensor.

[0005] For example, a diamond spin sensor system includes a diamond substrate containing NV centers, an optical system that transmits excitation light from a light source and irradiates the NV centers, an optical system that collects fluorescence from the NV centers and transmits it to a photodetector, and a waveguide that transmits microwaves from a power source and irradiates the NV centers. For example, Non-Patent Document 1 below discloses a configuration in which a diamond sensor is mounted on a coplanar waveguide and microwaves are irradiated. The diamond substrate has a rectangular parallelepiped shape, and excitation light is irradiated from the side of the diamond substrate, while fluorescence is collected from above the diamond substrate.

[0006] Japanese Patent Application Laid-Open No. 2003-35852

[0007] Yuta Masuyama, Yuji Hatano, Takayuki Iwasaki, Mutsuko Hatano, "High-sensitivity macro-diamond magnetometer using coplanar waveguides," Proceedings of the 79th Autumn Meeting of the Japan Society of Applied Physics (published September 5, 2018). Takaaki Oka, Ippei Nakamura, Hiroki Morishita, Masanori Fujiwara, Shiro Saito, Norikazu Mizuochi, "Temperature sensing using diamond NV center ensemble," Proceedings of the 78th Autumn Meeting of the Japan Society of Applied Physics (published August 25, 2017).

[0008] A diamond spin sensor system according to one aspect of the present disclosure includes a sensor unit including a diamond having a color center with electronic spin, a control power supply unit that generates excitation light to be irradiated onto the sensor unit, and a joint unit that connects the sensor unit and the control power supply unit, wherein the joint unit transmits the excitation light to the sensor unit to irradiate the diamond, and transmits fluorescence emitted from the diamond to the control power supply unit.

[0009] FIG. 1 is a block diagram showing the configuration of a diamond spin sensor system according to a first embodiment. FIG. 2 is a cross-sectional view showing the configuration of the joint shown in FIG. 1. FIG. 3 is a schematic diagram showing an installation example of the diamond spin sensor system shown in FIG. 1. FIG. 4 is a schematic view showing the configuration of a joint according to a first modified example. FIG. 5 is a schematic view showing the configuration of a joint according to a second modified example. FIG. 6 is a cross-sectional view showing the configuration of a joint according to a third modified example. FIG. 7 is a schematic view showing the configuration of a joint according to a fourth modified example. FIG. 8 is a block diagram showing the configuration of a diamond spin sensor system according to a second embodiment. FIG. 9 is a cross-sectional view showing the configuration of the microwave joint shown in FIG. 8. FIG. 10 is a schematic view showing the configuration of a diamond spin sensor system according to a first example. FIG. 11 is a diagram showing, in table form, measurement results using the configuration shown in FIG. 10. FIG. 12 is a schematic view showing the configuration of a measurement system according to a first comparative example. FIG. 13 is a diagram showing, in table form, measurement results using the configuration shown in FIG. 12. FIG. 14 is a schematic view showing the configuration of a diamond spin sensor system according to a second example. Fig. 15 is a diagram showing, in tabular form, the measurement results obtained by the configuration shown in Fig. 14. Fig. 16 is a schematic diagram showing the configuration of a diamond spin sensor system according to a third embodiment. Fig. 17 is a diagram showing, in tabular form, the measurement results obtained by the configuration shown in Fig. 16. Fig. 18 is a schematic diagram showing the configuration of a diamond spin sensor system according to a fourth embodiment. Fig. 19 is a diagram showing, in tabular form, the measurement results obtained by the configuration shown in Fig. 18.

[0010] [Problem to be Solved by the Present Disclosure] Conventional systems for maintaining and managing power cables include a mechanism for supplying power to a detection device via an electric cable separate from the power cable, a mechanism for detecting temperature and current at separate locations, and a mechanism for transmitting the detected information to equipment located on the ground via a wire or wireless connection. Therefore, a large number and variety of electronic components are used, such as electronic components for converting power for control purposes, electronic components for converting temperature and current into digital information, and electronic components for transmitting the information to the ground. Furthermore, since the equipment must be highly sealed for use in environments with large fluctuations, such as temperature cycles, heat builds up inside the equipment, shortening the lifespan of the electronic components and making them prone to failure. When an electronic component fails, the power supply via the power cable must be stopped and repairs must be performed. This is true not only for electric cables but also for high-voltage equipment. Furthermore, in conventional systems using a large number and variety of electronic components, performing maintenance before the electronic components fail requires setting maintenance intervals for each electronic component, taking into account the lifespan of each electronic component, which is a complex process.

[0011] Similar problems exist when sensing physical conditions (voltage, current, temperature, etc.) in real time not only in high-voltage environments such as power transmission and distribution facilities, but also in harsh environments such as high pressure, high temperature, extremely low temperature, strong acid and strong alkali.

[0012] Therefore, an object of the present disclosure is to provide a diamond spin sensor system that can detect physical conditions in harsh environments, has a long product life, and is easy to maintain.

[0013] Effect of the Present Disclosure According to the present disclosure, it is possible to provide a diamond spin sensor system that can detect physical states in harsh environments, has a long product life, and is easy to maintain.

[0014] [Description of Embodiments of the Present Disclosure] The contents of the embodiments of the present disclosure will be listed and described below. At least some of the embodiments described below may be combined in any combination.

[0015] (1) A diamond spin sensor system according to a first aspect of the present disclosure includes a sensor unit including a diamond having a color center with electronic spin, a control power supply unit that generates excitation light to be irradiated onto the sensor unit, and a joint unit that connects the sensor unit and the control power supply unit, the joint unit transmitting the excitation light to the sensor unit to irradiate the diamond, and transmitting fluorescence emitted from the diamond to the control power supply unit. As a result, since the sensor unit includes diamond that can withstand harsh environments as a sensor element, it is possible to realize a diamond spin sensor system that can detect physical states (voltage, current, temperature, etc.) in harsh environments, has a long product life, and is easy to maintain.

[0016] (2) In the above (1), the sensor unit can be placed in a first environment, and the control power supply unit can be placed in a second environment different from the first environment, and at least one of the voltage and temperature of the first environment can be greater by one order of magnitude or more than that of the second environment. This allows the control power supply unit to be placed in a normal environment, and realizes a diamond spin sensor system with a long product life and easy maintenance.

[0017] (3) In the above (1) or (2), the sensor unit may further include an optical waveguide that transmits excitation light to the diamond, and the optical waveguide may be formed of a transparent resin, a transparent nitride, or a transparent oxide, and the diamond and the connection between the diamond and the optical waveguide may be isolated from the outside air. This allows the sensor unit to be placed in a harsher environment.

[0018] (4) In the above (3), the joint may include an insulator, and the insulator may have a structure therein that allows the excitation light to pass through. This allows the excitation light to be transmitted efficiently and prevents damage to a mechanism disposed inside the joint.

[0019] (5) In the above (4), the diamond spin sensor system may have an uncoated optical transmission member disposed inside the joint that allows the excitation light to pass therethrough, or may have a space formed therein that allows the excitation light to pass therethrough, thereby reducing the number of manufacturing steps and the manufacturing cost.

[0020] (6) In the above (5), the diamond spin sensor system may have a space formed inside the joint and a lens that transmits the excitation light, thereby improving the transmission efficiency of the excitation light through the space inside the joint.

[0021] (7) In the above (6), the diamond spin sensor system may have a plurality of optical fibers that transmit the fluorescence emitted from the diamond and make it incident on the lens, and the plurality of optical fibers may be bundled together, thereby improving the collection efficiency of the fluorescence emitted from the diamond.

[0022] (8) In the above (1) or (2), the joint may include an insulator, and the insulator may have a structure that allows the excitation light to pass through the inside of the insulator. This allows the excitation light to be transmitted efficiently and prevents damage to a mechanism disposed inside the joint.

[0023] (9) In any one of the above (1) to (3) and (8), the diamond spin sensor system may have an uncoated optical transmission member disposed inside the joint portion, which allows the excitation light to pass through. This reduces the number of manufacturing steps and reduces manufacturing costs.

[0024] (10) In any one of the above (1) to (3) and (8), the diamond spin sensor system may have a space inside the joint portion through which the excitation light passes, thereby reducing the number of manufacturing steps and the manufacturing cost.

[0025] (11) In any one of (1) to (10) above, the diamond spin sensor system may further include an electromagnetic wave generator that outputs microwaves and a microwave coupling, the sensor may include a microwave circuit or a microwave waveguide, the microwave coupling may include a transmitter that radiates microwaves input from the electromagnetic wave generator and a receiver that receives the microwaves radiated from the transmitter, and the microwaves received by the receiver may be output to the microwave circuit or microwave waveguide included in the sensor, and the microwave coupling may be formed with a space that propagates the microwaves radiated by the transmitter. This allows the magnetic field to be calculated from the distance between two valleys in the observed frequency spectrum.

[0026] (12) In the above (11), the transmitter may include a first concave surface that radiates microwaves, and the receiver may include a second concave surface that focuses the microwaves, and the shape of each of the first concave surface and the second concave surface may be a part of a paraboloid or a sphere. This can improve the microwave transmission efficiency through the space within the microwave coupling.

[0027] [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. Therefore, detailed descriptions thereof will not be repeated.

[0028] 1, a diamond spin sensor system 100 according to a first embodiment of the present disclosure includes a sensor section 102, a joint section 104, a control power supply section 106, and an optical waveguide 108. The sensor section 102 is a NV －The optical waveguide 112 includes a diamond 110 containing a center (hereinafter referred to as an NV center), and an optical waveguide 112. The optical waveguide 112 includes a medium that transmits light and is coated with a resin or the like. The optical waveguide 112 is, for example, an optical fiber. The sensor unit 102 (specifically, the optical waveguide 112) is connected to the joint unit 104 by a connection unit 140. As will be described later, the joint unit 104 includes a medium that transmits light and is connected to the optical waveguide 108 by a connection unit 142. The optical waveguide 108 includes a medium that transmits light. The optical waveguide 108 is, for example, an optical fiber. The optical waveguide 112, the joint unit 104, and the optical waveguide 108 all transmit light in both directions.

[0029] Referring to FIG. 2 , the joint portion 104 includes a first housing portion 200, a second housing portion 202, and a third housing portion 204. The first housing portion 200 is, for example, an insulator made of ceramic, resin, or the like. The joint portion 104 further includes an optical transmission member 206, a cone-shaped member 208, and a cone-shaped member 210 housed inside the first housing portion 200 (i.e., the space surrounded by the cylindrical inner wall). The optical transmission member 206 is, for example, a rod-shaped quartz. The side surface of the optical transmission member 206 may be coated or uncoated. The cone-shaped member 208 is disposed at a first end of the optical transmission member 206, and the cone-shaped member 210 is disposed at a second end of the optical transmission member 206.

[0030] The second housing portion 202 and the third housing portion 204 are formed of, for example, resin. The joint portion 104 further includes an optical fiber 212 housed inside the second housing portion 202 and an optical connector 216 arranged on the wall surface of the second housing portion 202. A first end of the optical fiber 212 is connected to the cone-shaped member 208, and a second end of the optical fiber 212 is connected to the optical connector 216. The optical connector 216 is connected to the optical waveguide 108 (see FIG. 1). The optical connector 216 corresponds to the connecting portion 142 shown in FIG. 1. The joint portion 104 further includes an optical fiber 214 housed in the third housing portion 204 and an optical connector 218 arranged on the wall surface of the third housing portion 204. A first end of the optical fiber 214 is connected to the cone-shaped member 210, and a second end of the optical fiber 214 is connected to the optical connector 218. The optical connector 218 is connected to the optical waveguide 112 (see FIG. 1). The optical connector 218 corresponds to the connection section 140 shown in FIG.

[0031] It is preferable that the joint between the first housing section 200 and the second housing section 202 and the joint between the first housing section 200 and the third housing section 204 are tightly sealed with a sealing material such as resin to prevent moisture from entering the inside of the first housing section 200, the second housing section 202, and the third housing section 204. Similarly, it is preferable that the joint between the second housing section 202 and the optical connector 216 and the joint between the third housing section 204 and the optical connector 218 are tightly sealed with a sealing material.

[0032] The cone-shaped member 208 is a member for connecting the optical fiber 212 and the optical transmission member 206. That is, as will be described later, the cone-shaped member 208 causes the excitation light that is input from the optical connector 216 to the optical fiber 212, transmitted by the optical fiber 212, and emitted from a first end of the optical fiber 212 to be incident on the first end of the optical transmission member 206. The cone-shaped member 210 is a member for connecting the optical transmission member 206 and the optical fiber 214. That is, the cone-shaped member 210 collects the excitation light that propagates through the optical transmission member 206 and is output from a second end of the optical transmission member 206, and causes the collected light to be incident on the first end of the optical fiber 214. The cone-shaped members 208 and 210 are formed of, for example, glass (quartz glass, etc.).

[0033] Returning to FIG. 1 , the control power supply unit 106 irradiates the diamond 110 with excitation light and detects fluorescence emitted from the diamond 110. The control power supply unit 106 includes an excitation light generator 120, a filter 122, a focusing element 124, an LPF 126, a light detector 128, and a control unit 130. The control unit 130 includes a CPU (Central Processing Unit), a memory unit, and a wireless communication unit (none of which are shown). The processing performed by the control unit 130, which will be described later, is realized by the CPU reading and executing a program pre-stored in the memory unit. As will be described later, the control unit 130 acquires a signal (i.e., fluorescence intensity) detected by the light detector 128 and transmits it to an external device via the wireless communication unit. The external device calculates physical conditions (e.g., magnetic field and temperature) from the detection signal of the light detector 128 received from the control unit 130.

[0034] The excitation light generating unit 120 generates excitation light for exciting the NV center of the diamond 110 under the control of the control unit 130. The control unit 130 supplies, for example, a voltage to the excitation light generating unit 120 at a predetermined timing to cause the excitation light generating unit 120 to emit light. The excitation light is green light (i.e., wavelength 490 nm to 560 nm). The excitation light is preferably laser light, and the excitation light generating unit 120 is preferably a semiconductor laser (e.g., emitted light wavelength 532 nm).

[0035] The filter 122 is an element for separating the excitation light incident from the excitation light generating unit 120 from the light emitted from the diamond (i.e., fluorescence). For example, the filter 122 is a filter that cuts off (i.e., reflects) light with wavelengths equal to or less than a predetermined wavelength and passes light with wavelengths greater than the predetermined wavelength, or a bandpass filter that passes light with wavelengths within a predetermined wavelength range and cuts off (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 filter 122 is preferably a dichroic mirror with such a function.

[0036] The focusing element 124 focuses the excitation light input from the filter 122. The focusing element 124 is, for example, a spherical lens. The focusing element 124 inputs as much of the excitation light diffused and output from the excitation light generating unit 120 as possible into the end of the optical waveguide 108. The optical waveguide 108 has a first end and a second end, and transmits the excitation light incident on the first end from the focusing element 124 to the second end. The optical waveguide 108 also transmits the emitted light (i.e., fluorescence) from the diamond incident on the second end to the first end and outputs it.

[0037] The LPF 126 is a long-pass filter that passes light with wavelengths equal to or greater than a predetermined wavelength and cuts (e.g., reflects) light with wavelengths smaller than the predetermined wavelength. The emitted light from the diamond is red light and passes through the LPF 126, but the excitation light output from the excitation light generator 120 has a shorter wavelength and does not pass through the LPF 126. This prevents the excitation light emitted from the excitation light generator 120 from being detected by the light detector 128 and becoming noise, thereby reducing the detection sensitivity of the emitted light (i.e., fluorescence) from the diamond. The light detector 128 generates and outputs an electrical signal corresponding to the incident light. The light detector 128 is, for example, a photodiode. The output signal from the light detector 128 is acquired by the control unit 130. As described above, the signal acquired by the control unit 130 is transmitted to an external device via the wireless communication unit of the control unit 130. This allows the external device to calculate the physical conditions (e.g., magnetic field and temperature) at the location where the diamond 110 is located from the output signal from the light detector 128.

[0038] 3, the diamond spin sensor system 100 is installed in a power transmission facility (e.g., an overhead power transmission facility) and is used for the maintenance and management of power cables, the detection of abnormalities, etc. That is, the sensor unit 102 (diamond 110 and optical waveguide 112) is installed in a power transmission line 900, and the control power supply unit 106 is installed on an iron pole of a steel tower 902. The joint unit 104 is installed, for example, inside an insulator 904. The optical waveguide 108 connecting the joint unit 104 and the control power supply unit 106 is fixed to an arm of the steel tower 902, etc.

[0039] Using the NV center, the magnetic field can be calculated from changes in the ESR (Electron Spin Resonance) spectrum. It is also known that the resonance frequency of the NV center has temperature dependence in the range from 120 K to 700 K. For example, as disclosed in Non-Patent Document 2, temperature can be measured from changes in the ODMR (Opticaly Detected Magnetic Resonance) signal strength near the resonance frequency.

[0040] The diamond 110 of the sensor unit 102 detects the magnetic field generated by the current flowing through the power line 900 or fluorescence corresponding to the temperature of the power line 900. The detection signal is transmitted to the control power supply unit 106 via the joint unit 104 and the optical waveguide 108, and then transmitted to a device on the ground by the control power supply unit 106. This allows the magnetic field or temperature at the location where the diamond 110 is located to be detected. Only the sensor unit 102 is placed in the vicinity of the power line 900, where high voltages of several thousand kV (e.g., 6,600 kV) or more are transmitted, i.e., in a harsh high-voltage environment, while the optical waveguide 108 and control power supply unit 106 are placed in a normal environment away from the power line 900. The diamond 110 and optical waveguide 112 that make up the sensor unit 102 are not affected by the high-voltage environment, even when placed in that environment. The optical waveguide 108 and control power supply unit 106 are placed in a normal environment. Therefore, a diamond spin sensor system with a long product life and easy maintenance can be realized.

[0041] By configuring the joint 104 as shown in FIG. 2 , the joint 104 can be placed across two different environments. For example, the third housing 204 can be placed in a harsh environment, and the second housing 202 can be placed in a normal environment. In FIG. 3 , the joint 104 is placed between a high-voltage environment and a normal environment. Each component of the joint 104 is made of materials that are less susceptible to high voltage. This allows the control power supply 106 and the optical waveguide 108 to be placed in a normal environment, resulting in a diamond spin sensor system with a long product life and easy maintenance. Note that a "harsh environment" refers to an environment that is difficult for humans to enter. For example, in FIG. 3 , this refers to a high-voltage environment such as the vicinity of a power transmission line 900. A "normal environment" refers to an environment other than a "harsh environment." In a harsh environment, at least one of the electric field strength, magnetic field strength, temperature, and pressure is greater (e.g., by one or more orders of magnitude) than in a normal environment.

[0042] The optical waveguide 112 and the optical waveguide 108 may be formed from a light-transmitting resin, a light-transmitting nitride, or a light-transmitting oxide. The diamond 110 is preferably covered with a resin or ceramic to isolate it from the outside air. The connection between the diamond 110 and the optical waveguide 112 is also preferably sealed with a resin or ceramic to isolate it from the outside air. This allows the sensor unit 102 to be placed in a harsher environment.

[0043] As described above, an insulator can be used for the first housing 200 of the joint 104, and a configuration (i.e., the optical transmission member 206) for transmitting excitation light to the first housing 200 (i.e., the insulator) can be provided. This allows the excitation light to be transmitted efficiently, and prevents the mechanism disposed inside the joint 104 from being damaged by a harsh environment such as a high voltage.

[0044] As described above, it is optional whether or not the side surfaces of the optical transmission member 206 are coated. However, if the side surfaces of the optical transmission member 206 are not coated, the number of manufacturing steps can be reduced, and manufacturing costs can be reduced.

[0045] (First Modification) In the above, the joint unit 104 includes a rod-shaped optical transmission member 206 and optical fibers 212 and 214 (see FIG. 2 ). However, this is not limiting. Referring to FIG. 4 , the joint unit 104 may include an optical fiber 230 instead of the optical transmission member 206, the optical fiber 212, and the optical fiber 214. The optical fiber 230 is formed in a spiral shape and is disposed inside the first housing unit 200. Coatings 232 and 234 are disposed on both ends of the optical fiber 230, while the remaining portion of the optical fiber 230 is uncoated. The coatings 232 and 234 are formed, for example, by a resin coating. The both ends of the optical fiber 230, on which the coatings 232 and 234 are disposed, are connected to the optical connectors 216 and 218 (see FIG. 2 ).

[0046] The optical fiber 230 is fixed to the inner wall 240 of the first housing 200 by a plurality of support members 236. The support members 236 are formed of a fluororesin such as Teflon (registered trademark). This prevents uncoated portions of the optical fiber 230 from coming into contact with each other. Therefore, light input from the optical connector 216 to the optical fiber 230 (i.e., excitation light) can be stably transmitted to the optical connector 218, and light input from the optical connector 218 to the optical fiber 230 (i.e., fluorescent light) can be stably transmitted to the optical connector 216.

[0047] (Second Modification) When the optical transmission member 206 is disposed inside the first accommodating section 200 as shown in Fig. 2 , it is preferable to provide a mechanism for holding the optical transmission member 206. For example, referring to Fig. 5 , the optical transmission member 206 is held inside the first accommodating section 200 by a plurality of support members 250. The support members 250 are formed in an annular (donut-shaped) shape around the optical transmission member 206 using, for example, Teflon, and the outer periphery of the support member 250 is in contact with the inner wall 240 of the first accommodating section 200. This allows the optical transmission member 206 to be stably disposed inside the first accommodating section 200, and even if the optical transmission member 206 is subjected to mechanical vibrations in an environment (e.g., a power cable) in which the joint 104 is disposed, the internal configuration of the joint 104 can be maintained and damage to the inside of the joint 104 can be prevented.

[0048] (Third Modification) In the above, the optical transmission member 206 is disposed inside the joint 104 (see FIG. 2 ). However, this is not limiting. The light-propagating function of the space itself may also be utilized. Referring to FIG. 6 , the joint 114 according to the third modification includes the first housing 200, the second housing 202, and the third housing 204, the optical fiber 212, the optical fiber 214, the optical connector 216, and the optical connector 218. The joint 114 is similar to the joint 104 (see FIG. 2 ) except that the optical transmission member 206 is removed and the cone-shaped member 208 and the cone-shaped member 210 are replaced with lenses 300 and 302. A space 220 is formed surrounded by the cylindrical inner wall of the first housing 200. In FIG. 6 , elements designated with the same reference numerals as those in FIG. 2 have the same functions as those in FIG. 2 . Therefore, redundant description will not be repeated.

[0049] Both lens 300 and lens 302 are convex lenses. In joint portion 114, a first end of optical fiber 212 is disposed at the position of focal point F of lens 300, and a first end of optical fiber 214 is disposed at the position of focal point F of lens 302. As a result, light input to optical connector 216 and emitted from the first end of optical fiber 212, i.e., excitation light 304, enters lens 300 and is then output as parallel light from lens 300. The excitation light 304 output from lens 300 as parallel light enters lens 302 and is then focused from lens 302 toward focal point F of lens 302 and enters the first end of optical fiber 214.

[0050] Furthermore, light input to optical connector 218 and emitted from the first end of optical fiber 214, i.e., fluorescent light, enters lens 302 and is then output as parallel light from lens 302. The fluorescent light output as parallel light from lens 302 enters lens 300 and is then output from lens 300, where it is focused toward focal point F of lens 300 and enters the first end of optical fiber 212. Fluorescent light 306 then propagates through optical fiber 212 and is output from optical connector 216.

[0051] 6, the joint part 114 can be placed across two different environments, similar to the joint part 104 (see FIG. 2). For example, the third housing part 204 can be placed in a harsh environment, and the second housing part 202 can be placed in a normal environment. This allows the control power supply part 106 and the optical waveguide 108 to be placed in a normal environment, realizing a diamond spin sensor system with a long product life and easy maintenance.

[0052] As described above, the space 220 that allows the excitation light 304 to pass through is formed inside the joint 114. This reduces the number of manufacturing steps and the manufacturing cost compared to the joint 104 shown in FIG. 2 and the like.

[0053] As described above, the lenses 300 and 302 that transmit the excitation light 304 are disposed inside the joint 114. This makes it possible to improve the transmission efficiency of the excitation light 304 through the space 220 inside the joint 114.

[0054] (Fourth Modification) In the above, a single optical fiber 212 and a single optical fiber 214 are respectively disposed in the second housing portion 202 and the third housing portion 204 of the joint portion 114 (see FIG. 6 ). However, this is not limiting. A plurality of fibers may be disposed in the second housing portion 202 and the third housing portion 204, respectively. As shown in FIG. 7 , in the joint portion 114 (see FIG. 6 ), the optical fiber 212 and the optical fiber 214 may be replaced with a plurality of optical fibers 310 and a plurality of optical fibers 312, respectively, and the optical connector 216 and the optical connector 218 may be replaced with an optical connector 314 and an optical connector 316, respectively. The multi-fiber optical fiber cable 318 and the multi-fiber optical fiber cable 320 replace the optical waveguide 108 and the optical waveguide 112 (see FIG. 1 ), respectively. Note that the first housing portion 200, the second housing portion 202, and the third housing portion 204 are not shown in FIG. 7 .

[0055] The plurality of optical fibers 310 are connected to an optical connector 314, and the plurality of optical fibers 312 are connected to an optical connector 316. The plurality of optical fibers included in the plurality of optical fibers 310 are spliced ​​one-to-one with the optical fibers included in the multi-core optical fiber cable 318 by the optical connector 314. The plurality of optical fibers included in the plurality of optical fibers 312 are spliced ​​one-to-one with the optical fibers included in the multi-core optical fiber cable 320 by the optical connector 316. The plurality of optical fibers 310 and the plurality of optical fibers 312 are each bundled. A first end of one optical fiber (hereinafter referred to as the first optical fiber for excitation light) among the plurality of optical fibers 310 is positioned at the focal position of the lens 300, similar to the optical fiber 212 (see FIG. 6). A first end of one optical fiber (hereinafter referred to as the second optical fiber for excitation light) among the plurality of optical fibers 312 is positioned at the focal position of the lens 302, similar to the optical fiber 214 (see FIG. 6).

[0056] The pumping light 304 is input to one optical fiber (the optical fiber spliced ​​to the first pumping light optical fiber) of the multi-core optical fiber cable 318. As a result, similar to the joint portion 114 (see FIG. 6 ), the pumping light 304 propagates through the first pumping light optical fiber of the plurality of optical fibers 310, is emitted from the first end of the first pumping light optical fiber, enters the lens 300, and is output as parallel light from the lens 300. The pumping light 304 output as parallel light from the lens 300 enters the lens 302, is output from the lens 302, is focused toward the focal point F of the lens 302, and is input to the first end of the second pumping light optical fiber of the plurality of optical fibers 312. The pumping light 304 then propagates through one optical fiber of the multi-core optical fiber cable 320 spliced ​​to the second pumping light optical fiber, and is then irradiated onto the diamond 110.

[0057] The fluorescence emitted from diamond 110 is input to multiple optical fibers of multi-core optical fiber cable 320, excluding one optical fiber (the optical fiber spliced ​​to the second excitation light optical fiber). As a result, fluorescence 306 propagates through the multiple optical fibers 312, excluding the second excitation light optical fiber, and is emitted from the first end of each optical fiber (located near the focal point of lens 302). After entering lens 302, the fluorescence 306 is output from lens 302 as substantially parallel light. The fluorescence output from lens 302 as substantially parallel light enters lens 300, exits lens 300, and is focused toward the focal point of lens 300, before entering the first ends of the multiple optical fibers 310, excluding the first excitation light optical fiber. The fluorescence 306 then propagates through multiple optical fibers of multi-core optical fiber cable 318 that are not spliced ​​to the first excitation light optical fiber. This allows more of the fluorescence emitted from the diamond 110 to be incident on the optical fiber of the multi-fiber optical cable 320 and transmitted efficiently to the multi-fiber optical cable 318 .

[0058] As described above, a plurality of optical fibers 312 are provided to transmit the fluorescence emitted from the diamond 110 and make it incident on the lens 302, and the plurality of optical fibers are bundled together. This improves the efficiency of collecting the fluorescence emitted from the diamond 110.

[0059] Second Embodiment In the first embodiment, the diamond spin sensor system that does not use microwaves has been described, whereas the diamond spin sensor system according to the second embodiment uses microwaves.

[0060] The diamond spin sensor system 150 according to the second embodiment of the present disclosure includes a sensor unit 102, a joint unit 104, a control power supply unit 106, an optical waveguide 108, an electromagnetic wave generating unit 152, a microwave joint unit 154, a microwave transmission line 156, a microwave transmission line 158, and a microwave circuit 160. The diamond spin sensor system 150 is the diamond spin sensor system 100 shown in FIG. 1 , to which the electromagnetic wave generating unit 152, the microwave joint unit 154, the microwave transmission line 156, the microwave transmission line 158, and the microwave circuit 160 have been added. In FIG. 8 , elements with the same reference numerals as those in FIG. 1 have the same functions as those in FIG. 1 . Therefore, redundant description will not be repeated. In addition to the above-described functions, the control unit 130 also has the function of controlling the electromagnetic wave generating unit 152. That is, a program for controlling the electromagnetic wave generating unit 152 is stored in a memory unit included in the control unit 130, and is executed by a CPU included in the control unit 130.

[0061] The electromagnetic wave generating unit 152 generates electromagnetic waves (e.g., microwaves) under the control of the control unit 130. The generated electromagnetic waves are transmitted through a microwave transmission line 156 and input to the microwave joint 154. The microwave transmission line 156 is, for example, a coaxial cable. The microwave joint 154 inputs the input electromagnetic waves to a microwave transmission line 158 by propagating them inside the microwave joint 154. The microwave transmission line 158 transmits the input electromagnetic waves to a microwave circuit 160, which irradiates the electromagnetic waves onto the diamond 110. The microwave transmission line 158 is, for example, a coaxial cable. The microwave circuit 160 is, for example, a coil formed including an electrical conductor. The microwave circuit 160 may be a circuit such as a coplanar line or a microstrip line.

[0062] The control unit 130 controls the excitation light generating unit 120 to output excitation light 304 for a predetermined time (e.g., period t1) at a predetermined timing. The control unit 130 controls the electromagnetic wave generating unit 152 to output electromagnetic waves for a predetermined time (e.g., period t2) at a predetermined timing. Any appropriate pulse sequence may be used during period t2. This allows the diamond 110 to be irradiated with the excitation light and electromagnetic waves in a temporally and spatially combined manner. The control unit 130 captures the output signal of the light detecting unit 128 at a predetermined timing (e.g., within period t3) and stores it in the memory unit.

[0063] For example, after irradiating the diamond 110 (i.e., the NV center) with 2.87 GHz microwaves, it is excited by irradiating it with green light. As a result, the transition when the spin of the NV center returns 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, two valleys (i.e., signal drops) are observed in the ESR spectrum. The distance Δf (i.e., frequency difference) between the two observed valleys depends on the magnetic field strength at the position of the diamond 110. The control unit 130 transmits the output signal of the light detection unit 128 to an external device via a wireless communication unit, and the external device can calculate Δf and calculate the magnetic field from Δf.

[0064] 9 , the microwave coupling 154 includes a first housing portion 400, a second housing portion 402, and a third housing portion 404. The first housing portion 400 is, for example, an insulator made of ceramic, resin, etc. A space 406 surrounded by a cylindrical inner wall is formed inside the first housing portion 400.

[0065] The second housing 402 and the third housing 404 are formed, for example, from resin. The microwave joint 154 further includes a transmitter 410 housed inside the second housing 402, and a receiver 412, a high-frequency cut filter 414, and a microwave transmission line 416 housed in the third housing 404. Each of the transmitter 410 and the receiver 412 is, for example, an antenna, and has a concave surface (e.g., a paraboloid (e.g., a paraboloid of revolution or an elliptical paraboloid)) formed by a material that reflects electromagnetic waves. The transmitter 410 and the receiver 412 are arranged so that their openings face each other. Note that the concave surfaces of the transmitter 410 and the receiver 412 may be portions of a sphere. In this case, if the solid angle of the concave surface is small, electromagnetic waves incident parallel to the central axis of the concave surface can be focused to a single point (i.e., a focal point).

[0066] The end of the microwave transmission line 156 is located at the focal position of the transmitter 410. Electromagnetic waves propagating through the microwave transmission line 156 and radiated from the end of the microwave transmission line 156 are reflected by the transmitter 410 and radiated in parallel. The end of the microwave transmission line 416 is located at the focal position of the receiver 412. The electromagnetic waves radiated in parallel by the transmitter 410 are reflected by the receiver 412 and focused at the focal point of the receiver 412, and are received by the end of the microwave transmission line 416. The electromagnetic waves received by the microwave transmission line 416 are output to the high frequency cut filter 414. The high frequency cut filter 414 removes high frequencies above a predetermined frequency from the input electromagnetic waves and outputs them to the microwave transmission line 158. As a result, as described above, the electromagnetic waves output from the electromagnetic wave generating unit 152 are transmitted to the microwave circuit 160 via the microwave transmission line 156, the microwave joint unit 154 and the microwave transmission line 158, and are irradiated onto the diamond 110 by the microwave circuit 160.

[0067] As a result, as described above, the magnetic field can be calculated from the distance Δf between two valleys in the observed frequency spectrum.

[0068] As described above, the transmitting section 410 includes a first concave surface that radiates microwaves, the receiving section 412 includes a second concave surface that focuses microwaves, and the shape of each of the first and second concave surfaces is a part of a paraboloid or a sphere, thereby improving the transmission efficiency of microwaves through the space 406 within the microwave coupling section 154.

[0069] Furthermore, if the electromagnetic wave is a microwave and its wavelength is too long, the microwave can be carried on a millimeter wave, that is, modulated by the microwave using the millimeter wave as a carrier wave and transmitted. When irradiating a diamond with a microwave, if a microwave with a wavelength of about 10 cm is used as is, the long wavelength causes problems with straightness and focusing. Millimeter waves have a short wavelength of a few mm, so they are superior to microwaves in terms of straightness and focusing. Therefore, the millimeter wave is propagated using the carrier wave, and once the energy is collected by focusing, it is separated and extracted as a microwave and irradiated onto the diamond. This makes it possible to realize a system with improved energy efficiency.

[0070] In the above, a case has been described in which microwaves are transmitted to the microwave circuit 160 via the microwave transmission line 158 and then irradiated onto the diamond 110, but this is not limiting. Microwaves output from the microwave joint 154 may also be transmitted to the diamond 110 via a microwave waveguide and irradiated thereto. A microwave waveguide refers to a circuit with a cylindrical or rectangular cavity, and microwaves propagate inside the cavity. The microwave waveguide may be a coaxial cable through which microwaves can pass, or may be a cylindrical (hollow) one with a square cross section. For a rectangular cylindrical microwave waveguide, one with a size suitable for the wavelength of the microwave is used.

[0071] The experimental results are shown below. Using the diamond spin sensor system including the joint section as described above, the magnetic field generated by the current flowing through the electric wire was measured. (First Example) Referring to Fig. 10, the diamond spin sensor system according to the first example includes diamond 500, optical waveguide 502, optical waveguide 504, optical waveguide 510, measurement section 520, and power supply section 522. Optical waveguide 502, optical waveguide 504, and optical waveguide 510 are connected by optical connector 506 and optical connector 508.

[0072] Diamond 500 was produced as follows: Diamond containing 30 ppm of substitutional nitrogen was synthesized by a high-temperature, high-pressure method and formed into a size of 2 mm x 2 mm square and 2 mm thick. An electron beam with an energy of 3 MeV was irradiated onto the obtained diamond at 1 x 10 １８ cm －２ After irradiation with a dose of 1000 kJ / cm, the diamond was annealed at 950°C for 1 hour. － It was confirmed by ODMR spectroscopy (optically detected magnetic resonance spectroscopy) that color centers of the above formula are formed and that magnetism and temperature can be detected by their spins.

[0073] The optical waveguide 502 is connected to a first end of the optical waveguide 504 by an optical connector 506, and the optical waveguide 510 is connected to a second end of the optical waveguide 504 by an optical connector 508. The optical waveguide 504 is approximately 2 m long and spirally arranged inside an insulator 906 with a hole inner diameter of approximately 0.2 m and a hole length of approximately 0.6 m (see FIG. 4 for the joint). A 0.8 mm diameter linear optical guide made of quartz glass (uncoated) or an optical fiber with a core diameter of 200 μm (uncoated) was used for the optical waveguide 502 and the optical waveguide 510. A 0.8 mm diameter linear optical guide made of quartz glass or an optical fiber with a core diameter of 200 μm was also used for the optical waveguide 504. As described below, coated and uncoated versions were used to evaluate the difference in insulation durability.

[0074] The diamond 500 was attached to the tip of the optical waveguide 502 using a common translucent adhesive. The use of an adhesive allows for stable measurement of the fluorescence intensity from the diamond 500. The diamond 500, along with a portion of the optical waveguide 502, was wrapped in a heat-shrinkable tube 530, which was then heated and shrunk to isolate the diamond 500 from the outside air. If the diamond 500 were not covered with the heat-shrinkable tube 530, water droplets would adhere to the diamond 500 or the diamond 500 would be scratched, which could affect the detection of its magnetic properties. Covering the diamond 500 with the heat-shrinkable tube 530 prevents such problems from occurring.

[0075] A conductive wire 614 was placed on the laminated first plate 610 and insulating layer 612, and a diamond 500 coated with a heat-shrinkable tube 530 was placed on top of that. Hereinafter, the environment in which the diamond 500 is placed is referred to as the "first environment." The first plate 610 is made of a conductive metal. The conductive wire 614 is connected between a DC power supply 622 and a variable resistor 620, one end of which is grounded. The DC power supply 622 is capable of outputting up to 20 kV.

[0076] The measuring unit 520 generates excitation light (laser) to irradiate the diamond 500, and detects fluorescence emitted from the diamond 500 and transmitted through the optical waveguides 502, 504, and 510. The power supply unit 522 supplies power to operate the measuring unit 520. The measuring unit 520 and the power supply unit 522 were placed on a second plate 624 made of a conductive metal. Hereinafter, the environment in which the measuring unit 520 and the power supply unit 522 were placed is referred to as the second environment. A predetermined DC voltage lower than the voltage applied to the first plate 610 was supplied to the second plate 624 by a DC power supply 626.

[0077] The diamond spin sensor system shown in Figure 10 detected the fluorescence intensity from the diamond 500, and measured the magnetic field generated by the current flowing through the conductor 614 placed near the diamond 500 using two measurement methods (Measurement A and Measurement B, described below). We also evaluated the effects of coating the connection between the diamond 500 and the optical waveguide 502 (i.e., the heat-shrink tubing 530) and the voltage applied to the first plate 610 on which the diamond 500 is mounted. The current flowing through the conductor 614 was adjustable using a variable resistor 620, and was adjusted so that a steady-state current of 1 A flowed relative to the applied voltage. The experimental results are shown in Figure 11. The "Coating" column indicates whether the optical waveguide 504 was coated or not. The "Connection Air-Protected" column indicates whether the heat-shrink tubing 530 was used or not.

[0078] As measurement A, the intensity of the excitation light source is kept constant, and the diamond 500 is irradiated with the fluorescence, and the magnetic field is detected by observing the fluorescence, and the phenomenon of the fluorescence intensity decreasing is used (magnetic field detection using only the excitation light source). Since the magnetic field is detected by changes in the fluorescence intensity, if the change in the fluorescence intensity becomes small and is buried in noise, it is determined that magnetic field detection is impossible. As measurement B, in the configuration of FIG. 10, a configuration for irradiating microwaves to the diamond 500 is added, and the irradiated microwave frequency is changed to detect the fluorescence intensity, and the interval (frequency difference) of the peaks of the ODMR spectrum obtained is converted into a magnetic field (magnetic field detection using the ODMR spectrum). If the change in the fluorescence intensity becomes small and is buried in noise, it is impossible to obtain a spectrum, and it is determined that magnetic field detection is impossible.

[0079] The dielectric strength of the uncoated optical fiber and the uncoated optical guide was confirmed in advance. When the optical fiber or the optical guide was examined, a dielectric strength of 20 kV was confirmed along its length. Even when the optical fiber or the optical guide was spirally arranged in a hollow insulator (inner diameter of approximately 0.2 m, length of approximately 0.6 m), a dielectric strength of 20 kV was confirmed. The dielectric strength was measured by wrapping metal around both ends of the optical fiber or the optical guide to form measurement terminals. If a current of 0.1 mA or less flows between these terminals, the dielectric strength was determined to be sufficient. While the low-voltage plate is sometimes grounded (0 V), it may not be exactly 0 V due to the presence of a driving power supply, and 10 V was always applied in the experiment. In Figure 11, the voltage ratio represents the ratio of the voltage in the first environment (first plate 610) (specifically, 10 V) to the voltage in the second environment (second plate 624). The current flowing through the conductor 614 was adjusted by a variable resistor 620. That is, for each applied voltage to the first plate 610, adjustment was made so that a steady current of 1 A flowed in measurement A, and a steady current of 100 mA flowed in measurement B.

[0080] 11, in both Measurement A and Measurement B, the magnetic field generated by the current flowing through the conductor 614 could be detected by detecting the fluorescence intensity from the diamond 500. The fluorescence intensity tended to decrease as the magnetic field strength increased (i.e., as the voltage supplied from the DC power supply 622 increased). However, when a coated optical guide or optical fiber was used as the optical waveguide (see Experiments No. 9 and 11), a leakage current occurred as the applied voltage increased, affecting the excitation light source and microwave power supply, making stable measurements impossible.

[0081] When comparing an uncoated optical waveguide or uncoated optical fiber (see Experiments No. 1 to No. 8) with a coated optical waveguide or coated fiber (see Experiments No. 9 to No. 12), differences in insulation durability were observed in both Measurement Method A and Measurement Method B when the voltage ratio was three digits or more. That is, the uncoated optical waveguide had higher insulation durability than the coated optical waveguide. Furthermore, when comparing the case where the connection between the diamond 500 and the optical waveguide 502 was covered with a heat-shrinkable tube 530 (see Experiments No. 1 to No. 12) with the case where the heat-shrinkable tube 530 was not provided (see Experiments No. 13 and No. 14), differences were observed when the connection was contaminated with oil or oil and sand. That is, covering with the heat-shrinkable tube 530 enabled stable magnetic field detection without contamination or damage.

[0082] (First Comparative Example) As a first comparative example, a Hall element was used to measure a magnetic field in a voltage environment similar to that shown in FIG. 10 . Referring to FIG. 12 , the Hall element 630 was placed in the first environment (first plate 610), and the driver 632 was placed in the second environment (second plate 624). As in the first example, the voltage of the second plate 624 was kept constant (10 V), and the voltage of the first plate 610 was varied, and the Hall element 630 measured the magnetic field generated by the current flowing through the conductor 614. The results are shown in FIG. 13 . When the voltage ratio was one digit or greater (see Experiments No. 21 to No. 23), the driver 632 was affected, resulting in increased noise and failure, and the magnetic field could not be measured.

[0083] (Second Example) An experiment was conducted using a joint different from that of the first example. Referring to Fig. 14, the diamond spin sensor system according to the second example includes a diamond 500, an optical waveguide 502, an optical waveguide 544, a mirror 542, a lens 552, an optical waveguide 510, a measurement unit 520, and a power supply unit 522. The configuration shown in Fig. 14 is the same as that shown in Fig. 10, except that the optical waveguide 504 is replaced with an optical waveguide 544, a mirror 542, and a lens 552, and the optical connector 508 is removed (see Fig. 6 for the joint). The other components are the same as those shown in Fig. 10, so repeated explanations will not be repeated. The results of the experiment using the configuration shown in Fig. 14 are shown in Fig. 15.

[0084] A 1.5 mm diameter optical guide was used as the optical waveguide 544. The open first end face 546 of the optical waveguide 544 was positioned at the center of the first opening 908 of the insulator 906, facing the second opening of the insulator 906. The excitation light 540 (laser) output from the measurement unit 520 propagates through the air and is reflected by the mirror 542. The angle of the reflecting surface of the mirror 542 is adjustable. By adjusting the angle of the mirror 542, the excitation light 540 was incident on the first end face 546 of the optical waveguide 544, which was positioned at the center of the first opening 908 of the insulator 906. As a result, the excitation light 540 was propagated through the optical waveguide 544 and the optical waveguide 502 and irradiated onto the diamond 500.

[0085] Fluorescence 550 emitted from diamond 500 propagates through optical waveguide 502 and optical waveguide 544, is emitted from first end face 546 of optical waveguide 544, is collected by lens 552 arranged near the second opening of insulator 906, and enters optical waveguide 510. As a result, as shown in Fig. 15, fluorescence emitted from diamond 500 could be detected by measuring unit 520 in both measurements A and B.

[0086] (Third Example) An experiment was conducted using a joint different from those in the first and second examples. Referring to FIG. 16 , the diamond spin sensor system according to the third example includes a diamond 500, an optical waveguide 502, an optical waveguide 544, a lens 560, a mirror 542, a lens 552, an optical waveguide 510, a measurement unit 520, and a power supply unit 522. The configuration shown in FIG. 16 is the same as that shown in FIG. 14 , except that a lens 560 is added (see FIG. 6 for the joint). The lens 560 is disposed near the first opening 908 within the insulator 906. The other components are the same as those in FIG. 14 , so repeated explanations will not be repeated. The experimental results for the configuration shown in FIG. 16 are shown in FIG. 17 . The column labeled "Lens in insulator" indicates whether or not the lens 560 is present.

[0087] Excitation light 540 (laser) output from measurement unit 520 propagates through the air and is reflected by mirror 542. The angle of mirror 542 is adjusted, and excitation light 540 is made incident on first end face 546 of optical waveguide 544 located in the center of first opening 908 of insulator 906 via lens 560. This allows excitation light 540 to propagate through optical waveguide 544 and optical waveguide 502 and be irradiated onto diamond 500.

[0088] Fluorescence 550 emitted from diamond 500 propagates through optical waveguide 502 and optical waveguide 544, radiates from first end face 546 of optical waveguide 544, is collected by lens 560 arranged near first opening 908 of insulator 906 and lens 552 arranged near the second opening of insulator 906, and enters optical waveguide 510. As a result, as shown in Fig. 17, fluorescence emitted from diamond 500 could be detected by measuring unit 520 in both measurements A and B.

[0089] (Fourth Example) Using the same joint as in the first example, an experiment was conducted by changing the temperature of the environment in which the diamond was placed. Referring to Fig. 18, the diamond spin sensor system according to the fourth example includes a diamond 500, an optical waveguide 502, an optical waveguide 504, an optical waveguide 510, a measurement unit 520, and a power supply unit 522. The diamond spin sensor system shown in Fig. 18 is the same as the diamond spin sensor system shown in Fig. 10. Therefore, redundant description will not be repeated. However, the environments in which the diamond 500 and the measurement unit 520 are placed are different. That is, in the configuration shown in Fig. 10, the DC power supply 626 has been removed and a heater control unit 642 has been added.

[0090] A conductive wire 614 was placed on the stacked first plate 610 and first plate 640, and a diamond 500 coated with a heat-shrink tube 530 was placed on top of that (first environment). The first plate 640 includes a conductive metal plate and a heater (not shown) that generates heat by receiving power from a heater control unit 642. The first plate 640 can be heated to 600°C by the heater control unit 642. Experiments conducted with the first plate 640 (including components placed on the first plate 640) placed in a vacuum demonstrated that it could be heated to 1000°C. Unlike the first plate 610 (see FIG. 10 ), no voltage is applied to the first plate 640 from the DC power supply 622. Furthermore, unlike FIG. 10 , no voltage is applied to the second plate 624, on which the measurement unit 520 and power supply unit 522 are placed.

[0091] The insulation heat resistance of the uncoated optical guide or uncoated optical fiber used as the optical waveguide 504 was confirmed in advance. It was confirmed that the insulation heat resistance of 1000°C was achieved even when the optical waveguide 504 was spirally arranged inside a 0.5 m hollow insulator 906. The insulation heat resistance means that the diamond sensor is isolated so that the temperature of the driving power supply does not rise accordingly when the temperature on the diamond sensor side is high. Specifically, insulation heat resistance was determined to be sufficient if the temperature of the second plate 624 in the second environment did not rise by more than 10°C due to the influence of the first plate 640 in the first environment. The low-temperature side plate (second plate 624) was actually at room temperature (10°C to 20°C). In the fourth example, the low-temperature side plate (second plate 624) was kept at 10°C using a Peltier element.

[0092] Using the configuration shown in FIG. 18 , magnetic fields were measured in Measurements A and B, similar to the first embodiment. As in the first embodiment, the current flowing through the conductor 614 was adjusted using the variable resistor 620. That is, for each applied voltage, adjustment was made so that a steady-state current of 1 A flowed in Measurement A and a steady-state current of 100 mA flowed in Measurement B. The results are shown in FIG. 19 . In FIG. 19 , the plate temperature in the first environment represents the temperature of the first plate 640, and the plate temperature in the second environment represents the temperature of the second plate 624. As shown in Experiments No. 51 to 54, magnetic fields could be measured at all temperature ratios. Furthermore, by covering the connection between the diamond 500 and the optical waveguide 502 with a heat-shrinkable tube 530, magnetic fields could be detected stably without contaminating or damaging the diamond 500.

[0093] (Second Comparative Example) As a comparative example, an experiment was conducted using a thermocouple. In the configuration shown in Fig. 18, a thermocouple was placed in the first environment (first plate 640 and insulating layer 612), and the drive power supply for the thermocouple was placed in the second environment (second plate 624), and temperature measurement was performed. As a result, the temperature of the second environment affected the temperature of the first environment, making it impossible to accurately measure the temperature of the first environment.

[0094] 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.

[0095] 100, 150 Diamond spin sensor system 102 Sensor unit 104, 114 Joint unit 106 Control power supply unit 108, 112, 502, 504, 510, 544 Optical waveguide 110, 500 Diamond 120 Excitation light generating unit 122 Filter 124 Light-collecting element 126 LPF 128 Light detecting unit 130 Control unit 140, 142 Connection unit 152 Electromagnetic wave generating unit 154 Microwave joint unit 156, 158, 416 Microwave transmission line 160 Microwave circuit 200, 400 First housing unit 202, 402 Second housing unit 204, 404 Third housing unit 206 Optical transmission member 208, 210 Pyramidal member 212, 214, 230 Optical fiber 216, 218, 314, 316, 506, 508 Optical connector 220, 406 Space 232, 234 Coating portion 236, 250 Support member 240 Inner wall 300, 302, 552, 560 Lens 304, 540 Excitation light 306, 550 Fluorescence 310, 312 Multiple optical fibers 318, 320 Multi-core optical fiber cable 410 Transmitter 412 Receiver 414 High frequency cut filter 520 Measuring portion 522 Power supply portion 530 Heat shrink tube 542 Mirror 546 First end face 610, 640 First plate 612 Insulating layer 614 Conductor 620 Variable resistor 622, 626 DC power supply 624 Second plate 630 Hall element 632 Drive unit 642 Heater control unit 900 Power transmission line 902 Steel tower 904, 906 Insulator 908 First aperture F Focus

Claims

1. A sensor section containing a diamond having a color center with electron spin, A control power supply unit that generates excitation light to irradiate the sensor unit, It includes a joint that connects the sensor unit and the control power supply unit, The aforementioned joint portion is, The excitation light is transmitted to the sensor unit and irradiated onto the diamond. The fluorescence emitted from the diamond is transmitted to the control power supply unit. A diamond spin sensor system having a space inside the joint through which the excitation light passes.

2. The sensor unit is placed in the first environment, The control power supply unit is located in a second environment different from the first environment. The diamond spin sensor system according to claim 1, wherein the first environment has a voltage and temperature that are at least one order of magnitude greater than that of the second environment.

3. The sensor unit further includes an optical waveguide for transmitting the excitation light to the diamond, The optical waveguide is formed from a translucent resin, a translucent nitride, or a translucent oxide. The diamond spin sensor system according to claim 1 or 2, wherein the diamond and the connection portion between the diamond and the optical waveguide are isolated from the outside air.

4. The aforementioned joint portion includes an insulating insulator, The diamond spin sensor system according to claim 3, wherein the insulator has a structure that allows the excitation light to pass through the inside of the insulator.

5. The diamond spin sensor system according to claim 4, wherein an uncoated optical transmission member for passing the excitation light is further disposed inside the joint portion.

6. A sensor part comprising a diamond having a color center having electron spin, A control power supply unit that generates excitation light to irradiate the sensor unit, It includes a joint that connects the sensor unit and the control power supply unit, The aforementioned joint portion is, The excitation light is transmitted to the sensor unit and irradiated onto the diamond. The fluorescence emitted from the diamond is transmitted to the control power supply unit. Inside the aforementioned joint, A space is formed through which the excitation light passes, A diamond spin sensor system having a lens that allows the excitation light to pass through.

7. The system has a plurality of optical fibers that transmit the fluorescence emitted from the diamond and cause it to enter the lens. The diamond spin sensor system according to claim 6, wherein the plurality of optical fibers are bundled together.

8. The aforementioned joint portion includes an insulating insulator, The diamond spin sensor system according to claim 1 or claim 2, wherein the insulator has a structure that allows the excitation light to pass through the inside of the insulator.

9. The diamond spin sensor system according to claim 1 or claim 2, wherein an uncoated optical transmission member for passing the excitation light is further disposed inside the joint portion.

10. An electromagnetic wave generator that outputs microwaves, Further including a microwave joint, The sensor unit includes a microwave circuit or a microwave waveguide. The aforementioned microwave joint is, A transmitting unit that emits microwaves input from the electromagnetic wave generating unit, The receiving unit includes the receiving unit that receives the microwaves radiated from the transmitting unit, The microwave received by the receiving unit is output to the microwave circuit or microwave waveguide included in the sensor unit. The diamond spin sensor system according to claim 1 or claim 2, wherein a space for propagating microwaves radiated by the transmitting unit is formed in the microwave joint portion.

11. A sensor part comprising a diamond having a color center having electron spin, A control power supply unit that generates excitation light to irradiate the sensor unit, It includes a joint that connects the sensor unit and the control power supply unit, The aforementioned joint portion is, The excitation light is transmitted to the sensor unit and irradiated onto the diamond. The fluorescence emitted from the diamond is transmitted to the control power supply unit. An electromagnetic wave generator that outputs microwaves, Further including a microwave joint, The sensor unit includes a microwave circuit or a microwave waveguide. The aforementioned microwave joint is, A transmitting unit that emits microwaves input from the electromagnetic wave generating unit, The receiving unit includes the receiving unit that receives the microwaves radiated from the transmitting unit, The microwave received by the receiving unit is output to the microwave circuit or microwave waveguide included in the sensor unit. The microwave joint section has a space formed therein for the propagation of microwaves radiated by the transmitting section. The transmitting unit includes a first concave surface that emits microwaves, The receiving unit includes a second concave surface for focusing the microwaves, A diamond spin sensor system in which the shapes of the first concave surface and the second concave surface are part of a parabolic or spherical surface.