Diamond sensor

Abstract

The diamond sensor includes: a diamond having a color center with electron spin; and a sensor head housing the diamond. The diamond includes: a reflective surface that reflects excitation light propagating through an optical system and entering the interior of the diamond; and a flat surface that allows the excitation light to enter the interior of the diamond and causes emitted light from the color center to exit from the diamond. The reflective surface reflects the emitted light from the color center after being excited by the excitation light and focuses the light toward the direction of the optical system. The angle formed by a specific crystal plane of the diamond with a low index relative to a reference plane perpendicular to a predetermined reference direction fixed on the sensor head, i.e., a first deviation angle, is 3° or less, and the surface roughness Ra of the flat surface is 20 nm or less.

Description

Technical Field

[0001] This disclosure relates to diamond sensors. This application claims priority based on Japanese Application No. 2024-027997, filed February 28, 2024. All descriptions set forth in that application are incorporated herein by reference. Background Technology

[0002] Diamond sensors using diamond NVcenters (hereinafter referred to as NV centers) are known. When the NV center, composed of nitrogen (N) at the substitution site of carbon (C) in diamond and the adjacent vacancy (V: vacancy) of the nitrogen, carries a negative charge, its substrate state becomes a triplet state (i.e., spin S = S=1). The negatively charged NV center is denoted as NV. - The NV center, hereinafter referred to as the NV center for convenience, emits fluorescence at a wavelength of approximately 637 nm (red light) when excited by a laser with a wavelength of approximately 530 nm (i.e., green light). The intensity of the fluorescence varies depending on the spin state of the NV center, which in turn varies based on magnetic resonance between the magnetic field applied to the NV center and microwave or radio frequency waves, thus enabling its use as a magnetic sensor.

[0003] For detection, an optical system is used to transmit and irradiate excitation light from a light source onto a diamond containing NV centers, and a waveguide is used to transmit and irradiate microwaves from a power source onto the diamond. Furthermore, an optical system is used to focus fluorescence from the NV centers of the diamond and transmit it to a photodetector. As for the diamond containing NV centers, a pyramidal-shaped diamond is disclosed in Patent Document 1 below.

[0004] Existing technical documents Patent documents Patent document 1: International Publication No. 2022 / 210695. Summary of the Invention

[0005] The diamond sensor disclosed herein includes: a diamond having a color center with electron spin; and a sensor head housing the diamond, the diamond including: a reflective surface for reflecting excitation light propagating through an optical system and entering the interior of the diamond; and a flat surface for allowing the excitation light to enter the interior of the diamond and for causing emitted light from the color center to exit from the diamond, the reflective surface reflecting the emitted light from the color center after being excited by the excitation light and focusing the light toward the direction of the optical system, the angle formed by a specific crystal plane of the diamond with a low index relative to a reference plane perpendicular to a predetermined reference direction fixed on the sensor head, i.e., a first deviation angle, is 3° or less, and the surface roughness Ra of the flat surface is 20 nm or less. Attached Figure Description

[0006] Figure 1A This is a left-side view of the diamond sensor according to an embodiment of the present disclosure.

[0007] Figure 1B yes Figure 1A The front view of the diamond sensor is shown.

[0008] Figure 2 This is a three-dimensional view of the diamond shown in Figure 1.

[0009] Figure 3 It is a cross-sectional view showing the relationship between the diamond housed in the sensor head and the reference orientation.

[0010] Figure 4 It is a cross-sectional view showing the angle between the crystal facet of diamond and the bottom surface of diamond formed by cutting.

[0011] Figure 5 It is a three-dimensional diagram showing the relationship between the four directions of the NV axis of diamond and the magnetic field of the object being measured.

[0012] Figure 6 It is a schematic representation in Figure 5 The graph shows the relationship between the observed signal strength and the electromagnetic wave frequency under the conditions shown.

[0013] Figure 7 It is a schematic representation of from Figure 5 The graph shown illustrates the relationship between signal strength and electromagnetic wave frequency when the magnetic field is slightly tilted.

[0014] Figure 8 It is a schematic representation of from Figure 5 The graph shown illustrates the relationship between signal strength and electromagnetic wave frequency under conditions where the magnetic field is significantly tilted.

[0015] Figure 9A This is a front view of the diamond involved in the first variation.

[0016] Figure 9B yes Figure 9A The diamond shown is shown in a top view.

[0017] Figure 9C yes Figure 9A The right-side view of the diamond shown.

[0018] Figure 10 This is a cross-sectional view of the diamond sensor involved in the second variation.

[0019] Figure 11 It means Figure 10 The image shown is a three-dimensional representation of a diamond.

[0020] Figure 12A This is a front view of the diamond involved in the third variation.

[0021] Figure 12B yes Figure 12A The diamond shown is shown in a top view.

[0022] Figure 12C yes Figure 12A The right-side view of the diamond shown.

[0023] Figure 13A This is a front view showing the diamond that has been produced.

[0024] Figure 13B yes Figure 13A The diamond shown is shown in a top view.

[0025] Figure 13C yes Figure 13A The right-side view of the diamond shown.

[0026] Figure 14 It is presented in tabular form to create multiple [symbols / parameters]. Figures 13A to 13C The diagram shows the results of an experiment conducted with the same diamond as the one shown, in which excitation light was incident from the bottom surface.

[0027] Figure 15 It is presented in tabular form to create multiple [symbols / parameters]. Figures 13A to 13C The diagram shows the results of an experiment conducted with the same diamond as the one shown, in which excitation light was incident on the incident surface. Detailed Implementation

[0028] [The problem this disclosure aims to solve] If the crystal facets of the diamond containing the NV center cannot be precisely positioned relative to the object being measured (e.g., a magnetic field), the ODMR (Optically Detected Magnetic Resonance) spectrum broadens and splits into multiple segments. Therefore, to measure external fields (magnetic fields, electric fields, and temperature), microwaves need to be scanned over a wide frequency range, making it difficult to perform high-precision measurements in a short time. For example, if a diamond sensor is manufactured by embedding diamond in a housing, it is not easy to identify the crystal facets of the embedded diamond from outside the housing, making it difficult to position the diamond crystal facets appropriately relative to the object being measured.

[0029] Therefore, the purpose of this disclosure is to provide a diamond sensor that can accurately and easily configure the crystal facets of diamond onto the object being measured.

[0030] [The Effects of This Disclosure] According to this disclosure, a diamond sensor is provided that can accurately and easily configure the crystal facets of diamond onto the object being measured.

[0031] [Description of embodiments of this disclosure] The embodiments of this disclosure are described below. At least some of the embodiments described below can be combined in any way.

[0032] (1) The diamond sensor according to the first aspect of this disclosure includes: a diamond having a color center with electron spin; and a sensor head housing the diamond, the diamond including: a reflective surface that reflects excitation light propagating through an optical system and entering the interior of the diamond; and a flat surface that allows the excitation light to enter the interior of the diamond and causes emitted light from the color center to exit from the diamond. The reflective surface reflects the emitted light from the color center after being excited by the excitation light and focuses the light toward the direction of the optical system. The angle formed by a specific low-index crystal plane of the diamond, i.e., a first deviation angle, relative to a reference plane perpendicular to a predetermined reference direction fixed on the sensor head, is 3° or less, and the surface roughness Ra of the flat surface is 20 nm or less. Thus, the crystal plane of the diamond can be positioned on the object to be measured with high precision and ease. Therefore, high-precision measurement can be performed in a short time.

[0033] (2) The diamond sensor according to the second aspect of this disclosure includes: a diamond having a color center with electron spin; and a sensor head housing the diamond, the diamond including: an incident surface into which excitation light propagating through an optical system enters; a reflecting surface that reflects the emitted light emitted from the color center after being excited by the excitation light incident from the incident surface, focusing the light in a direction that guides it to a light-receiving optical system of a light-receiving element; and a flat surface from which the emitted light exits from the diamond, the area of ​​the reflecting surface being larger than the area of ​​the incident surface, the reflecting surface guiding the emitted light emitted from the same position in different directions to the light-receiving optical system through multiple optical paths, the angle formed by the specific crystal orientation of the diamond with a low index relative to a reference surface perpendicular to a predetermined reference direction fixed to the sensor head, i.e., a first deviation angle, is 3° or less, and the surface roughness Ra of the flat surface and the incident surface is 20 nm or less. Therefore, the crystal facets of the diamond can be precisely and easily positioned on the object to be measured. Thus, high-precision measurements can be performed in a short time.

[0034] (3) In (1) above, the diamond can also be shaped as a triangular pyramid with the flat surface as the base of the pyramid, and the angle between the diamond crystal plane {100} or crystal plane {111} and the base, i.e., the second deviation angle, is 3° or less. Therefore, if the base of the diamond in the triangular pyramid is configured to be perpendicular to the reference direction, the deviation angle of the crystal plane {100} or crystal plane {111} relative to the reference plane perpendicular to the reference direction can be made to be 3° or less, thus making it easy to accommodate the diamond in the sensor head with high positional accuracy.

[0035] (4) In (2) above, the diamond can also be shaped like a truncated pyramid, with the flat surface being the base of the truncated pyramid. The angle between the diamond's crystal facet {100} or crystal facet {111} and the base, i.e., the second deviation angle, is 3° or less. Thus, if the base of the diamond in the truncated pyramid is configured to be perpendicular to the reference direction, the deviation angle of the crystal facet {100} or crystal facet {111} relative to the reference surface perpendicular to the reference direction can be made to be 3° or less, thus making it easy to accommodate the diamond in the sensor head with high positional accuracy.

[0036] (5) In (1) or (3) above, the sensor head may have a sensing surface, the diamond may be in the shape of a triangular pyramid, and the angle between the sensing surface and the base of the triangular pyramid, i.e., the third deviation angle, may be less than 1°. Thus, if the sensing surface of the sensor head is precisely positioned on the object to be measured, the crystal facets of the diamond may be precisely positioned on the object to be measured, thereby improving the detection sensitivity of the diamond sensor.

[0037] (6) In (3) or (4) above, the fourth deviation angle may be 3° or less. If the second deviation angle is the angle between the diamond crystal facet (001) and the bottom surface, the fourth deviation angle may be the angle between any side of the bottom surface and the <100> direction of the diamond. If the second deviation angle is the angle between the diamond crystal facet (111) and the bottom surface, the fourth deviation angle may be the angle between any side of the bottom surface and the <1-10> direction of the diamond. Thus, the diamond crystal facet can be positioned on the object being measured with high precision. In addition, the diamond can be easily housed in the sensor head with high positional accuracy.

[0038] (7) In (5) above, the angle formed by one side of the sensing surface and any side of the bottom surface of the diamond, i.e., the fifth deviation angle, can be 1° or less. This allows the crystal facets of the diamond to be precisely positioned on the object being measured. Furthermore, it facilitates the precise placement of the diamond within the sensor head.

[0039] (8) In (1) above, the diamond may also be the shape formed by removing the vertices of the base of the triangle in the triangular pyramid, such that the first lateral face formed by removing the vertices has an angle of 80° or more and 100° or less relative to the base, and the exterior angle of the hexagon formed by removing the vertices is 57° or more and 63° or less. This makes it easier to handle the diamond constituting the diamond sensor, improves the processing accuracy of the diamond, and improves the detection accuracy of the diamond sensor.

[0040] (9) In (2) above, the diamond may also be the shape formed by removing the vertices of the triangle that serves as the lower base of the triangular pyramid. The first side face formed by removing the vertices forms an angle of 80° or more and 100° or less relative to the base, and the exterior angle of the hexagon formed by removing the vertices is 57° or more and 63° or less. As a result, the diamond constituting the diamond sensor is easier to handle, the processing accuracy of the diamond is improved, and the detection accuracy of the diamond sensor is improved.

[0041] (10) In any of (1) to (9) above, the first deviation angle may be 1° or less. Thus, the crystal facets of diamond can be positioned on the object of measurement with higher precision.

[0042] (11) In (10) above, the first deviation angle may also be 0.1° or less. As a result, the crystal facets of diamond can be positioned on the object of measurement with even higher precision.

[0043] (12) In any of (3), (4), (6) and (7) above, the second deviation angle may be less than 1°. Thus, diamond can be accommodated in the sensor head with higher precision.

[0044] (13) In (12) above, the second deviation angle may also be less than 0.1°. This allows the diamond to be accommodated in the sensor head with even higher precision.

[0045] (14) In (6) above, the fourth deviation angle may also be 1° or less. This allows the crystal facets of the diamond to be positioned on the object being measured with high precision. In addition, the diamond can be accommodated in the sensor head with even higher precision.

[0046] (15) In (5) above, the third deviation angle may also be 0.1° or less. Therefore, if the sensing surface is precisely positioned on the object to be measured, the crystal facets of diamond can be positioned on the object to be measured with even higher precision, thereby further improving the detection sensitivity of the diamond sensor.

[0047] (16) In (7) above, the fifth deviation angle may also be 0.1° or less. This allows the crystal facets of the diamond to be positioned on the object being measured with higher precision. In addition, it is easier to accommodate the diamond in the sensor head with higher positional precision.

[0048] (17) In (8) or (9) above, the exterior angle of the hexagon may be 59° or more and 61° or less. As a result, it is easier to hold the diamond that constitutes the diamond sensor, the processing accuracy of the diamond is further improved, and the detection accuracy of the diamond sensor is further improved.

[0049] (18) In any of (8), (9) and (17) above, the maximum value of the diameter length of the first side is 50 μm or more, and is less than 40% of the length of one side of the triangle. This allows for stable holding of the diamond. Furthermore, it suppresses the reduction of the NV center, achieving a balance between improved sensor accuracy and reduced fluorescence intensity based on improved diamond processing precision.

[0050] (19) In any of (8), (9), (17) and (18) above, the diamond may also include a second side surface formed by cutting off each side of the bottom surface. Thus, when cutting the diamond, the workpiece, i.e., the diamond, can be easily held using a two-point gripping jig.

[0051] [Details of the embodiments disclosed herein] 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.

[0052] Reference Figure 1A as well as Figure 1B The diamond sensor 100 disclosed herein includes a diamond 102, an optical fiber 104, and a sensor head 106 that houses the diamond 102 and the optical fiber 104. Figure 1A as well as Figure 1BFor convenience, the diamond 102 and optical fiber 104 are magnified for display, and their magnification is not constant. The diamond 102 is formed from a single diamond crystal containing NV centers composed of nitrogen (N) and pores (V). The optical fiber 104 transmits excitation light 112 irradiating the NV centers of the diamond 102 and transmits fluorescence 114 emitted from the NV centers to a detection device (not shown). The excitation light 112 is green light (i.e., wavelength 490 nm to 560 nm). The excitation light 112 is, for example, laser light generated by a semiconductor laser (e.g., emitting light with a wavelength of 532 nm). The fluorescence 114 is detected by a detection device (e.g., a photodiode). The sensor head 106 includes a λ / 4 converter 132 that functions as a resonator for irradiating the diamond 102 with microwaves and a λ / 4 open-circuit stub 134. The λ / 4 open-circuit stub 134 is configured to hold the diamond 102. The λ / 4 open-circuit stub 134 is configured to be bent at approximately 90° in its center, forming an angle of approximately 90° with the λ / 4 converter 132 at the connection point. Microwaves are generated by a microwave source (not shown) and transmitted to the λ / 4 converter 132 via a coaxial cable 130.

[0053] The sensor head 106 is prismatic, with a rectangular cross-section perpendicular to its axis. For example, the cross-section perpendicular to the axis in the sensor head 106 has a width of 5 mm × a height of 10 mm and a length of 20 mm. The sensor head 106 is formed of resin, for example, and has a reference orientation display 110 on its surface. As described later, the reference orientation display 110 is used to determine the crystal facets of the diamond 102. The reference orientation display 110 has a shape that can be visually observed. For example, the reference orientation display 110 is a straight-line convex or concave portion. The reference orientation display 110 can also be a visually observable color pattern disposed on the surface of the sensor head 106. Additionally, the sensor head 106 has a sensing surface 108. Figure 1B A horizontal edge 116 of the sensing surface 108 is shown. The sensing surface 108 is a surface perpendicular to the axis of the sensor head 106. Therefore, the sensing surface 108 is perpendicular to the reference direction display 110, and the crystal facets of the diamond 102 can also be determined through the sensing surface 108. Furthermore, as long as the information used to determine the crystal facets of the diamond 102 can be visually confirmed and displayed on the sensor head 106, the shape and color of the information can be fixed on the sensor head 106.

[0054] Reference Figure 2 Diamond 102 is a triangular pyramid having vertices A to D and a flat face 120. The flat face 120 is the base of the triangular pyramid. Diamond 102 is formed, for example, in a pyramidal shape. Figure 2The orthogonal X, Y, and Z axes are shown. That is, angles α, β, and γ are all 90°. The flat surface 120 is an equilateral triangle. The diamond 102 is configured such that the flat surface 120 is perpendicular to the axis of the sensor head 106 (i.e., perpendicular to the reference direction display 110). Excitation light 112 output from the optical fiber 104 is incident on the flat surface 120. The incident excitation light 112 irradiates the NV center 122 in the diamond 102. Fluorescence 114 emitted from the NV center 122 is emitted in all directions. The emitted fluorescence 114 is reflected multiple times by the sides of the triangular pyramid, namely surfaces ABD, ACB, and ADC, and is emitted from the flat surface 120. The fluorescence 114 emitted from the flat surface 120 is incident on the optical fiber 104 and is transmitted to the detection device as described above.

[0055] The flat surface 120 is ground such that excitation light 112 is effectively incident onto the flat surface 120. The three sides (faces ABD, ACB, and ADC) of the diamond 102, which is a triangular pyramid, are ground such that fluorescence 114 is effectively reflected. The surface roughness Ra of the flat surface 120 and the three sides is, for example, less than 20 nm. Thus, excitation light 112 is effectively incident onto the flat surface 120. Fluorescence 114 is effectively reflected and emitted from the flat surface 120.

[0056] The flat surface 120 of diamond 102 is, for example, a crystal face (001). The flat surface 120 can also be a crystal face (111). Furthermore, the flat surface 120 can be any crystal face with a low index (small Miller index) including crystal faces {100}, {110}, and {111}. Crystal face {100} represents crystal face (100) and crystal face equivalent to crystal face (100). Similarly, crystal face {110} represents crystal face (110) and crystal face equivalent to crystal face (110), and crystal face {111} represents crystal face (111) and crystal face equivalent to crystal face (111). For example, when the flat surface 120 is a crystal face (001), one side of the flat surface 120 is formed, for example, along the

[100] direction or the

[010] direction. For example, one side of the flat surface 120 formed along the

[100] direction (e.g.) Figure 2 The shown edge CD is configured as follows, with Figure 1B The edge 116 of the shown sensing surface 108 is parallel. In the case where the flat surface 120 is a crystal plane (011), one side of the flat surface 120 is formed, for example, along the

[100] direction or the [0-11] direction. For example, one side of the flat surface 120 formed along the

[100] direction (e.g.) Figure 2 The shown edge CD is configured as follows, with Figure 1BThe edge 116 of the shown sensing surface 108 is parallel. In the case where the flat surface 120 is a crystal plane (111), one side of the flat surface 120 is formed, for example, along the [1-10] direction, the [10-1] direction, or the [01-1] direction. For example, one side of the flat surface 120 formed along the [1-10] direction (e.g.) Figure 2 The shown edge CD is configured as follows, with Figure 1B The edges 116 of the sensing surface 108 shown are parallel. By forming the diamond 102 in this way and configuring it in the sensor head 106, as described later, the detection accuracy of fluorescence emitted from the NV center of the diamond 102 can be improved.

[0057] The sensor head 106 has a recess (not shown) for accommodating a pyramidal diamond 102, in which the diamond 102 is disposed, such that the crystal facets of the diamond 102 are perpendicularly arranged in the reference direction shown 110. (Refer to...) Figure 3 By utilizing the precision of the recess used to accommodate the diamond 102, the crystal facet of the diamond 102 can be tilted relative to the reference plane 124, which is perpendicular to the reference direction 110. Figure 3 The diagram shows a case where the flat surface 120 is formed parallel to the crystal plane. For example, the tilt angle (hereinafter referred to as the deviation angle) θ1 is 3° or less. Furthermore, the deviation angle (first deviation angle) θ1 is the angle between the crystal plane (i.e., the flat surface 120) and the reference plane, with the vertical plane 124 relative to the reference direction display 110 as the reference plane. This angle is the angle (positive acute angle) within a plane perpendicular to the line intersecting these two planes. Therefore, as described later, by arranging the reference direction display 110 of the diamond sensor 100 on the object being measured, the crystal plane of the diamond 102 can be arranged on the object being measured with high precision and ease. Consequently, as described later, high-precision measurements can be performed in a short time.

[0058] In the above description, it is assumed that the flat surface 120 of diamond 102 is formed parallel to the crystal plane; however, depending on the machining precision, the flat surface 120 may deviate from the crystal plane. (Refer to...) Figure 4 The angle θ2 formed by the flat surface 120 and the crystal surface 126, i.e., the deviation angle (second deviation angle), is 3° or less. Therefore, if the flat surface 120 of the pyramidal diamond 102 is arranged perpendicularly to the reference direction display 110, the deviation angle of the crystal surface {100} or the crystal surface {111} relative to the reference plane (vertical plane 124) perpendicular to the reference direction display 110 can be 3° or less. Thus, the diamond 102 can be easily accommodated in the sensor head 106 with high positional accuracy.

[0059] Reference Figure 5The orientation of the NV center contained in diamond 102, the orientation of the magnetic field used as an example for measurement, and the fluorescence intensity detected by ODMR are explained. There are four possible orientations for the NV axis of the NV center. Figure 5 In the diagram, [V] marked with square brackets indicates an empty pore, and the numbers [1] to [4] marked with square brackets represent the four possible locations for nitrogen (N) relative to [V]. Figure 5 The crystal orientation is shown in the figure. Diamonds containing N in equal proportions at positions [1] to [4] are used, such as... Figure 5 As shown, when ODMR is performed under the applied magnetic field B1, magnetic field B2, or magnetic field B3, the following results can be obtained: Figure 6 The diagram shown has two valleys. Magnetic fields B1, B2, and B3 are parallel to the <001>, <010>, and <100> directions, respectively. It can be obtained that... Figure 6 The diagram shown is because the angle between the NV axis and magnetic fields B1, B2, or B3 is 54.7° when N is located at positions [1] to [4]. That is, the same magnetic field strength is detected by the NV sensor at each position of N from [1] to [4], therefore the frequency (i.e., the interval between the two valleys) that is proportional to the magnetic field strength is equal. The interval between the two valleys, i.e., the frequency difference, is proportional to the magnetic field strength. Therefore, each valley is a monotonic valley with a minimum value, thus allowing for high-precision calculation of the interval between the two valleys and, consequently, high-precision calculation of the magnetic field strength.

[0060] On the other hand, for example, when ODMR is performed with the magnetic field B1 tilted relative to the center of NV as shown by the dashed arc-shaped arrow, it is possible to obtain... Figure 7 The chart shown. Figure 5 The dashed arrows shown indicate the slopes within the planes containing [1] and [2], or the slopes within the planes containing [3] and [4]. Figure 7 The chart shown illustrates that the shapes of the valleys are not monotonous, containing multiple minima. Furthermore, their half-height to full-width ratio (hereinafter simply referred to as half-height to full-width) is... Figure 6 The half-height and width are large. Therefore, the calculation accuracy of the interval between the two valleys is reduced, and the calculation accuracy of the magnetic field strength is also reduced. Consequently, to measure the magnetic field, a wide frequency range of microwave scanning is required, making it difficult to perform high-precision measurements in a short time. The same applies when magnetic fields B2 and B3 are tilted relative to the center of NV.

[0061] Furthermore, in the direction of magnetic field B1 and... Figure 5 The charts obtained using ODMR show the different directions in which the dotted, arc-shaped arrows are tilted. Figure 8 As shown. In Figure 8 The shapes of the valleys in the chart shown are not monotonous, but rather... Figure 7 It contains more minimum values. Additionally, its half-width / half-height aspect ratio... Figure 7 The half-height and width are large. Therefore, the calculation accuracy of the interval between the two valleys is further reduced, and the calculation accuracy of the magnetic field strength is further reduced. Thus, to measure the magnetic field, it is necessary to scan the microwave over a wide frequency range, making it difficult to perform high-precision measurements in a short time. The same applies when magnetic fields B2 and B3 are tilted relative to the center of NV.

[0062] Therefore, in order to improve the detection accuracy of the sensor and shorten the measurement time, it is important to configure the NV center with high precision relative to the object being measured (e.g., a magnetic field). For this purpose, it is important to configure the crystal facets (e.g., crystal facet {100}) of the diamond 102 with high precision to the object being measured. As described above, a reference direction display 110 is provided on the sensor head 106, and the diamond 102 is configured on the sensor head 106 such that the flat surface 120 is almost perpendicular to the reference direction display 110. At this time, the configuration is such that the first deviation angle θ1 is 3° or less. Thus, as described above, the crystal facets of the diamond 102 can be configured with high precision and easily to the object being measured. Therefore, high-precision measurement can be achieved in a short time. Furthermore, when the diamond is configured such that the crystal facets {111} or {110} are perpendicular to the magnetic field of the object being measured, the angles formed by the magnetic field and the four NV axes are different, but the angles formed by the magnetic field and each NV axis can be determined. Crystal face {110} is equivalent to crystal face (110). By using diamond with N contained in the same proportions in positions [1] to [4], the shape of the graph obtained by ODMR (number of valleys, etc.) is determined. Therefore, if the crystal face {111} or crystal face {110} of diamond can be arranged with high precision and perpendicularly to the object being measured (magnetic field), the magnetic field strength can be easily calculated.

[0063] The aforementioned first deviation angle θ1 can be 1° or less. This allows for a more precise alignment of the crystal facets of the diamond 102 onto the object being measured. Furthermore, the first deviation angle θ1 can be 0.1° or less. This allows for an even more precise alignment of the crystal facets of the diamond 102 onto the object being measured.

[0064] The aforementioned second deviation angle θ2 can be 1° or less. This allows the diamond 102 to be housed in the sensor head 106 with higher precision. Furthermore, the second deviation angle θ2 can be 1° or less. This allows the diamond 102 to be housed in the sensor head 106 with even higher precision.

[0065] As described above, the diamond 102 can be disposed on the sensing surface 108. For example, the angle between the sensing surface 108 and the flat surface 120, i.e., the deviation angle (third deviation angle), is less than 1°. Therefore, if the sensing surface 108 is disposed with high precision on the object to be measured, the crystal facet of the diamond 102 can be disposed with high precision on the object to be measured, thereby improving the detection sensitivity of the diamond sensor 100.

[0066] The third deviation angle can be 0.1° or less. Therefore, if the sensing surface 108 is precisely positioned on the object being measured, the crystal planes of the diamond 102 can be positioned on the object with even higher precision, further improving the detection sensitivity of the diamond sensor 100. Furthermore, the third deviation angle can be 0.05° or less.

[0067] As described above, when a crystal plane (001) is used as a flat surface 120, one side of the flat surface 120 is formed, for example, along the <100> direction. Depending on the processing accuracy, the direction of one side of the flat surface 120 can be tilted relative to the <100> direction. The deviation angle (fourth deviation angle), which indicates the allowable range of tilt angle, is 3° or less. Furthermore, when the flat surface 120 is a crystal plane (111), one side of the flat surface 120 is formed, for example, along the <1-10> direction (including the [1-10] direction, and the [10-1] direction and [01-1] direction, which are equivalent to it). Similarly, depending on the processing accuracy, the direction of one side of the flat surface 120 can be tilted relative to the <1-10> direction. The fourth deviation angle is 3° or less. Therefore, the crystal plane of the diamond 102 can be positioned on the measuring object with high precision. Furthermore, the diamond 102 can be easily accommodated in the sensor head 106 with high positional accuracy.

[0068] The fourth deviation angle can be 1° or less. This allows the crystal facets of the diamond 102 to be precisely positioned on the object being measured. Furthermore, the diamond 102 can be easily housed in the sensor head 106 with even higher precision. Additionally, the fourth deviation angle can be 0.1° or less.

[0069] When the diamond 102 is positioned on the sensor head 106, as described above, one side of the flat surface 120 is configured to be parallel to the edge 116 of the sensing surface 108. Due to its configuration precision, one side of the flat surface 120 can be tilted relative to the edge 116. The deviation angle (fifth deviation angle), representing the allowable tilt angle, is 1° or less. Therefore, the crystal facet of the diamond 102 can be positioned on the object being measured with high precision. Furthermore, the diamond 102 can be easily accommodated in the sensor head 106 with high positional precision.

[0070] The fifth deviation angle can be 0.1° or less. This allows for more precise placement of the crystal facets of the diamond 102 onto the object being measured. Furthermore, it facilitates the placement of the diamond 102 into the sensor head 106 with greater positional accuracy. Additionally, the fifth deviation angle can be 0.05° or less.

[0071] In the above content, the sensor head 106 is a prism with a rectangular cross-section (see reference). Figure 1B The description is provided, but it is not limited to this. The sensor head 106 can be a prism with a square cross-section. Alternatively, the sensor head 106 can also be a column with a circular or elliptical cross-section.

[0072] (First variation) The above description addresses the case of diamond 102 being a triangular pyramid, but it is not limited to this. (See reference...) Figures 9A to 9C The diamond 102A used in the diamond sensor 100 can be the shape of a triangular pyramid after removing the vertices of its base. That is, in the diamond 102A, in... Figure 2 In the diamond 102 shown, a portion of length L1 from vertex B is perpendicularly cut off by the straight line connecting vertex A and vertex B in the top view. The first side surface 202 formed by this cut is connected to the bottom surface 200 (and...). Figure 2 The flat surface 120 corresponds to the bottom surface 200 (angle θ3 is 90°). Similarly, the portions of length L2 starting from vertex C and from vertex D are cut off perpendicularly to the bottom surface 200. The first side surface 204 and the first side surface 206 formed by the cut are perpendicular to the bottom surface 200. The length L1 is greater than the length L2.

[0073] The cutting described above is performed to facilitate the holding of the diamond. That is, by using a three-point gripping clamp to hold the first side surface 202, first side surface 204, and first side surface 206, the diamond 102A can be held stably. The areas of the first side surface 202, first side surface 204, and first side surface 206 only need to be large enough for easy holding. For example, the length L3 of one of the three sides of the first side surface 202, which is also included in the bottom surface 200, is 50 μm or more. The same applies to the first side surface 204 and first side surface 206. Furthermore, in Figure 2 When angles α, β, and γ are all 90°, length L3 is the maximum span length of the first side surface 202 when it is perpendicular to the bottom surface 200. Span length refers to the distance between two points on the outer perimeter of the figure. However, if the first side surface 202 is not perpendicular to the bottom surface 200, the maximum span length of the first side surface 202 may differ from length L3. Furthermore, in... Figure 2When the angles α, β, and γ shown are less than 90°, even if the first side surface 202 is perpendicular to the bottom surface 200, the maximum span length of the first side surface 202 may differ from the length L3. Therefore, to make it easy to hold, the maximum span length of the first side surface 202 should be 50 μm or more.

[0074] On the other hand, if the portion removed from the pyramid becomes larger, the number of NV centers in the diamond decreases, thus reducing the detected fluorescence intensity. Furthermore, the area of ​​the fluorescence-reflecting surface decreases, which also reduces the fluorescence intensity. Therefore, there is an acceptable range for the amount of material removed; the maximum span length of the first side 202 (e.g., length L3) is less than 40% of one side of the base of the original pyramid (length L4). The same applies to the first side 204 and the first side 206. This allows for stable holding of the diamond. Furthermore, by suppressing the reduction of NV centers, a balance can be achieved between improved sensor accuracy due to increased diamond processing precision and reduced fluorescence intensity.

[0075] The base 200 is hexagonal, with an angle θ4 of 120° between any two adjacent sides, and an exterior angle θ5 of 60°. By cutting away the sides (triangles), the lateral faces (210, 212, and 214) of the triangular pyramid become pentagonal lateral faces. Figures 9A to 9C The crystal orientation of diamond 102A is shown. That is, the bottom face 200 is the crystal plane (001), and the direction of the edge CD, which is one side of the bottom face, is the <100> direction. The different cut amounts (L1>L2) as described above are to enable the identification of the edge in the <100> direction. If the edge in the <100> direction can be identified by other methods such as marking the surface of the diamond, then the length L1 can be equal to the length L2.

[0076] The diamond 102A is disposed in the sensor head 106 such that the bottom surface 200 serves as the incident surface for excitation light and the exit surface for fluorescence, and the side surfaces 210, 212, and 214 serve as the reflective surfaces for fluorescence. Therefore, as described above, the bottom surface 200, side surfaces 210, 212, and 214 are ground to a surface roughness Ra of less than 20 nm. Thus, excitation light is effectively incident onto the bottom surface 200, and fluorescence is effectively reflected by the side surfaces 210, 212, and 214 and emitted from the bottom surface 200.

[0077] In the fabrication of diamonds used in diamond sensors, a triangular pyramid (e.g., a corner pyramid) of approximately 1 mm is typically fabricated using laser processing, taking into account the crystal planes. However, this method is difficult to control, making it challenging to precisely process the crystal planes. Consequently, it is difficult to grind the incident surface for excitation light and the reflective surface for fluorescence. As described above, the diamond 102A has a first side surface 202, a first side surface 204, and a first side surface 206 perpendicular to the base surface 200. This makes it easier to control, improving the processing accuracy of the diamond and thus the detection accuracy of the diamond sensor. Specifically, the diamond 102A can be stably held with its three sides using a fixture. Therefore, it is easier to precisely process the crystal planes and to grind the base surface 200, etc. Furthermore, it is easier to precisely position the diamond 102A onto the sensor head 106.

[0078] Due to insufficient machining precision when producing diamond 102A from diamond 102, it may be impossible to form diamond 102A as described above. An allowable range is determined based on the use of diamond 102A in the diamond sensor 100. For example, the allowable range for angle θ3 is 90° ± 10°, i.e., 80° or more and 100° or less. The allowable range for angle θ5 is 60° ± 3°, i.e., 57° or more and 63° or less. This makes it easier to control the diamond constituting the diamond sensor, improves the machining precision of the diamond, and improves the detection accuracy of the diamond sensor.

[0079] The allowable range for the exterior angle θ5 is 60°±1°, that is, above 59° and below 61°. This makes it easier to handle the diamond that constitutes the diamond sensor, further improving the diamond's machining accuracy and thus the sensor's detection accuracy.

[0080] The allowable range of angle θ3 can be 90°±5° (above 85° and below 95°) or 90°±1° (above 89° and below 91°). This makes it easier to handle the diamond that constitutes the diamond sensor, further improving the diamond's machining accuracy and thus the sensor's detection accuracy.

[0081] The maximum span length of the first side face 202 can be 100 μm or more. The maximum span length of the first side face 202 can be 150 μm or more, or 200 μm or more. The same applies to the first side face 204 and the first side face 206. If the area of ​​each of the first side face 202, the first side face 204, and the first side face 206 increases, it becomes easier to hold the diamond 102A. However, if the portion cut from the triangular pyramid increases, the detected fluorescence intensity decreases as described above. Therefore, the maximum span length of the first side face 202 can be less than 30% of one side (length L4) of the original triangular pyramid's base, or less than 20%. The same applies to the first side face 204 and the first side face 206. The less the amount of material removed from the diamond 102A, the higher the detection accuracy of the diamond sensor.

[0082] (Second variation) In the above content, such as Figure 1A As shown, for the bottom surface of diamond 102 ( Figure 2 The case where excitation light 112 is incident on a flat surface 120 has been described, but it is not limited to this. (See also...) Figure 10 In the second variation of the diamond sensor 150, excitation light 112 is incident on the diamond 152 from the side opposite to the bottom surface of the triangular pyramid-shaped diamond 152. The diamond sensor 150 is configured similarly to the diamond sensor 100, except that the incident direction of the excitation light 112 on the diamond is different. That is, the diamond sensor 150 includes a diamond 152, an optical fiber 104, an optical fiber 154, and a sensor head 156 that houses the diamond 152, the optical fiber 104, and the optical fiber 154. The diamond 152 is formed from a single diamond crystal containing NV centers. The optical fiber 154 transmits the excitation light 112 that irradiates the NV centers of the diamond 152. The optical fiber 104 transmits fluorescence 114 emitted from the NV centers in the diamond 152. The excitation light 112 is, for example, a laser generated by a semiconductor laser (e.g., the wavelength of the emitted light is 532 nm). The fluorescence 114 is detected by a detection device (e.g., a photodiode). The sensor head 156 is prismatic (with a square cross-section perpendicular to the axis), and is formed, for example, from resin. A reference orientation display 110 is configured on the surface of the sensor head 156, similar to that of the diamond sensor 100.

[0083] Reference Figure 11 Diamond 152 is Figure 2The diamond 102 shown is a truncated pyramid after vertex A has been removed. Excitation light 112 is incident on the diamond 152 from the incident surface 160 formed by removing vertex A. The NV center 122 in the diamond 152 is irradiated by the incident excitation light 112. Fluorescence emitted from the NV center 122 is emitted in all directions. The emitted fluorescence is reflected multiple times through the sides of the truncated pyramid, i.e., the three trapezoidal faces, and exits from the flat surface 120. Fluorescence 114 emitted from the flat surface 120 is incident on the optical fiber 104 and transmitted to the detection device as described above. Furthermore, of the two base surfaces of the diamond 152, which are truncated pyramids (i.e., the incident surface 160 and the flat surface 120), the incident surface 160, which has a relatively smaller area, is called the upper base, and the flat surface 120, which has a relatively larger area, is called the lower base.

[0084] The incident surface 160 is ground such that the excitation light 112 is effectively incident from the incident surface 160 into the diamond 152. The three trapezoidal faces of the diamond 152, which is a truncated pyramid, are ground such that the fluorescence 114 is effectively reflected. The flat surface 120 from which the fluorescence 114 is emitted is also ground. The surface roughness Ra of the incident surface 160, the flat surface 120, and the three trapezoidal faces is, for example, less than 20 nm. Thus, the excitation light 112 is effectively incident into the diamond 152. The fluorescence 114 is effectively reflected and emitted from the flat surface 120.

[0085] The crystal facets and crystal orientation of diamond 152 are the same as those of diamond 102. That is, the flat surface 120 is a crystal facet {100}. The flat surface 120 can also be a crystal facet {111}. For example, in the case where the flat surface 120 is a crystal facet (001), one side of the flat surface 120 (e.g., side CD) is formed, for example, along the <100> direction. The sensor head 156 has a recess for receiving diamond 152, in which diamond 152 is disposed, thereby the crystal facets of diamond 152 are arranged perpendicularly to the reference direction display 110.

[0086] By utilizing the precision of the recess formed in the sensor head 156 to accommodate the diamond 152, the crystal plane of the diamond 152 can be configured at an angle relative to a reference plane perpendicular to the reference direction display 110 (see reference). Figure 3 Assume that the flat plane 120 is formed parallel to the crystal plane, and the first deviation angle θ1 (refer to...) Figure 3 The angle is 3° or less. Therefore, similar to the diamond sensor 100, the reference direction display 110 of the diamond sensor 150 is positioned on the object being measured, thereby enabling the crystal plane of the diamond 152 to be positioned on the object with high precision and ease. Thus, high-precision measurements can be performed in a short time.

[0087] Additionally, depending on the machining precision, the flat surface 120 may deviate from the crystal plane (see reference). Figure 4The angle between the flat plane 120° and the crystal plane is the second deviation angle θ2 (refer to...). Figure 4 The angle is 3° or less. Therefore, if the flat surface 120 of the diamond 152 is arranged perpendicularly to the reference direction display 110, the deviation angle of the crystal plane {100} or crystal plane {111} relative to the reference plane perpendicular to the reference direction display 110 can be 3° or less. Thus, the diamond 152 can be easily accommodated in the sensor head 156 with high positional accuracy.

[0088] The first deviation angle θ1 can be less than 1°. Alternatively, the first deviation angle θ1 can be less than 0.1°. This allows for the precise placement of the crystal facets of diamond 152 onto the object being measured.

[0089] The second deviation angle θ2 can be less than 1°. This allows the diamond 152 to be accommodated in the sensor head 156 with even higher precision.

[0090] As described above, when a crystal plane (001) is used as the flat surface 120 of the diamond 152, one side of the flat surface 120 is formed, for example, along the <100> direction. Depending on the machining accuracy, the direction of one side of the flat surface 120 can be tilted relative to the <100> direction. The deviation angle (fourth deviation angle), which indicates the allowable tilt angle, is 3° or less. Furthermore, when the flat surface 120 is a crystal plane (111), one side of the flat surface 120 is formed, for example, along the <110> direction. Similarly, depending on the machining accuracy, the direction of one side of the flat surface 120 can be tilted relative to the <110> direction. The fourth deviation angle, which indicates the allowable tilt angle, is 3° or less. Therefore, the crystal plane of the diamond 152 can be positioned on the object being measured with high precision. Additionally, the diamond 152 can be easily accommodated in the sensor head 156 with high positional accuracy.

[0091] The fourth deviation angle can be less than 1° or less than 0.1°. This allows for the precise placement of the diamond 102 crystal facets on the object being measured.

[0092] The above description describes the case where the sensor head 156 is a prism with a square cross-section, but it is not limited to this. The sensor head 156 can also be a prism with a rectangular cross-section. Alternatively, the sensor head 156 can also be a column with a circular or elliptical cross-section.

[0093] (Third variation) The above description addresses the case of diamond 152 being a truncated triangular pyramid, but it is not limited to this. (See reference...) Figures 12A to 12C The diamond 152A used in the diamond sensor 150 can be cut... Figure 11 The shapes behind the vertices of the base (lower base) of the triangular pyramid frustum are shown. That is, in diamond 152A, in... Figures 9A to 9C In the diamond 102A shown, a predetermined portion including vertex A is removed. The height H2 of the removed portion is determined so that the incident surface 220 formed by the removal is the same size as the cross-section of the optical fiber 154. This makes it easier to handle the diamond constituting the diamond sensor, improves the diamond's processing accuracy, and thus improves the detection accuracy of the diamond sensor.

[0094] In the above content, regarding diamond with an incident surface for excitation light ( Figure 11 Diamond 152, and Figures 12A to 12C Diamond 152A), such as Figure 10 The illustration shows the case where excitation light is incident from the incident surface, but it is not limited to this. Alternatively, [the following can be considered]... Figure 11 ,as well as Figures 12A to 12C The diamond shown is used for Figure 1A as well as Figure 1B The configuration shown is as follows. That is, it can be used... Figure 11 or Figures 12A to 12C A diamond is used instead of diamond 102, and excitation light is incident from the flat surface (i.e., the bottom surface). (The following will be discussed further.) Figures 13A to 13C The diamond 152B shown can also be used as follows: Figure 10 Excitation light is incident from the incident surface as shown, or as... Figure 1A Excitation light is incident from the flat surface (i.e., the bottom surface) as shown.

[0095] The above description illustrates the use of diamond with NV centers in diamond sensors, but it is not a limitation. Any diamond possessing a color center with electron spin can be used. A color center with electron spin is a center that forms a spin triplet state and emits light when excited; NV centers are a representative example. In addition, color centers with electron spin are also known to exist in silicon-void centers (i.e., Si-V centers), germanium-void centers (i.e., Ge-V centers), and tin-void centers (i.e., Sn-V centers). Therefore, diamonds containing these can also be used instead of diamonds containing NV centers to construct diamond sensors.

[0096] Example 1 The effectiveness of the diamond sensor disclosed herein is illustrated below through examples. A single diamond crystal is laser-processed to fabricate... Figures 12A to 12C The diamond 152A shown is then cut along each edge of the bottom surface to create the material. Figures 13A to 13C Diamond 152B is shown.

[0097] exist Figures 13A to 13C The image shows vertices A to D of a triangular pyramid (corner pyramid) before the removal of its apex. (See reference...) Figure 2Angles α, β, and γ are all 90°. The length L4 of one side of the base of the triangular pyramid is 1.732 mm. The height H1 from the base before cutting to vertex A is 0.707 mm. The height H2 of the cut portion including vertex A is 0.035 mm. The length L1 of the cut portion including vertex B is 0.6 mm. The lengths L2 of the cut portions including vertex C and vertex D are both 0.4 mm.

[0098] exist Figures 12A to 12C In the diamond 152A shown, one side of the bottom surface 200 is cut along the edge CD and perpendicular to the bottom surface 200. This forms... Figures 13A to 13C The rectangular second side surface 222 is shown. The width W of the cut portion is 0.1 mm. Similarly, the edges of the bottom surface 200 are cut perpendicularly to the bottom surface 200 along edges BC and DB, respectively. By cutting, the rectangular second side surfaces 224 and 226 are formed. Thus, when grinding diamond, the workpiece, i.e., the diamond, can be easily held using a two-point gripping jig. That is, the parallel first side surface and the second side surface (e.g., the first side surface 202A and the second side surface 222) are held by the jig.

[0099] By excision, by Figures 12A to 12C The bottom surface 200, the first side surface 202, the first side surface 204, and the first side surface 206 shown respectively form Figures 13A to 13C The diagram shows a base surface 200A, a first side surface 202A, a first side surface 204A, and a first side surface 206A. The base surface 200A is hexagonal, and the first side surfaces 202A, 204A, and 206A are all pentagons. The length L5 of one side of the first side surface 202A that is included in the base surface 200A is 0.462 mm. Similarly, the lengths of the five sides of the first side surface 204A and the five sides of the first side surface 206A that are included in the base surface 200A are both 0.231 mm.

[0100] As described above, the bottom surface 200A, the first side surface 202A, the first side surface 204A, the first side surface 206A, and the incident surface 220 are ground to a surface roughness Ra of less than 20 nm. Other surfaces are not ground.

[0101] First side faces 202A, 204A, and 206A are all pentagons; therefore, the maximum span length of each face may differ from the length of the side contained within the base face 200A. For example, the maximum span length of the first side face 202A is length L6. Furthermore, in Figure 2When the angles α, β, and γ shown are less than 90°, even if the first side surface 202A is perpendicular to the bottom surface 200A, the maximum span length of the first side surface 202A may differ from the length L6. In any case, to facilitate the handling of the diamond 152B, the maximum span length of each of the first side surface 202A, the first side surface 204A, and the first side surface 206A should be 50 μm or more.

[0102] On the other hand, if the portion cut from the pyramid becomes larger, the number of NV centers in the diamond decreases, thus reducing the detected fluorescence intensity. Therefore, the maximum span length of each of the first side face 202A, the first side face 204A, and the first side face 206A should be less than 40% of one side (length L4) of the base of the original pyramid.

[0103] Example 2 The same diamond as in Example 1 was fabricated. Specifically, using the bottom face as the crystal plane (001) and the direction of one side of the bottom face as <100>, multiple diamonds with a hypotenuse length of 550 μm before the vertex was removed were fabricated. Figures 13A to 13C The diamond shown is of the shape shown. The results of measurements using the prepared diamond are presented. Figure 14 .exist Figure 14 In this study, the deviation angle (θ2) between the bottom surface and the crystal plane, and the deviation angle between the bottom edge and the crystal direction were measured using X-ray diffraction. The angle θ3 between the bottom surface and the side surface, the exterior angle θ5 of the hexagonal bottom surface, and the maximum span length of the side surface were measured using an optical microscope. The deviation angles between the sensor head and the bottom surface, and between the sensor head and the bottom edge, were measured using an optical microscope and a surface shape measuring machine (manufactured by Zygo Corporation). The deviation angle between the sensor head and the crystal plane was measured using X-ray diffraction. The fluorescence intensity was measured as the current value of the photodiode by shining excitation light into the bottom surface of each diamond. In addition, ODMR was measured by scanning the frequency of microwaves while irradiating them in continuous wave (CW) mode, and the full width at half maximum (FWHM) was measured when a magnetic field of 1 mT was applied perpendicularly to the sensor head. According to the results, the ODMR of the sample with a deviation angle between the sensor head and the crystal plane greater than 3 degrees is very large, making it difficult to obtain high-precision magnetic sensitivity. It can be seen that the larger the maximum span length of the side, the higher the grinding precision and the smaller the deviation angle between the sensor head and the crystal surface. The smaller the deviation angle between the sensor head and the crystal surface, the smaller the half-width at half-maximum and the more sensitive the measurement.

[0104] Example 3 Using diamonds prepared in the same manner as in Example 2, from the incident surface of each diamond (refer to...) Figures 13A to 13CThe fluorescence intensity was measured by incident excitation light onto the incident surface (220°). The results are shown in... Figure 15 The measurement methods for each item are the same as in Example 2. Figure 15 Samples 21 to 27 and samples 31 to 33 respectively correspond to Figure 14 Samples 1 to 7 and samples 11 to 13. The measured values ​​for diamond itself are related to... Figure 14 The same value. The measured value (offset angle) regarding the configuration of the sensor head and the diamond varies depending on the diamond's orientation towards the sensor head. Figure 14 The results show that the ODMR of samples with a sensor head offset angle greater than 3 degrees has a very large half-width at half-maximum (WHM), making it difficult to obtain high-precision magnetic sensitivity. The smaller the offset angle between the sensor head and the crystal plane, the smaller the WHM of the ODMR and the more sensitive the measurement.

[0105] 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 based on the detailed description of the invention and is expressed by each claim, including all modifications within the meaning and scope of the statements therein.

[0106] Explanation of reference numerals in the attached figures 100, 150: Diamond sensors; 102, 102A, 152, 152A, 152B: Diamond; 104, 154: Fiber optic cable; 106, 156: Sensor head; 108: Perception Surface; 110: Reference direction display; 112: Excitation light; 114: Fluorescence; 116: Side; 120: Flat surface; 122: NV Center; 124: Vertical plane; 126: Crystal facet; 130: Coaxial cable; 132: λ / 4 converter; 134: λ / 4 open circuit stub; 160, 220: Incident surfaces; 200, 200A: bottom surface; 202, 204, 206, 202A, 204A, 206A: First side view; 210, 212, 214: Side view; 222, 224, 226: Second side view; A, B, C, D: Vertices; α, β, γ, θ3, θ4, θ5: angle; θ1, θ2: Deviation angles; H1, H2: Height; L1, L2, L3, L4, L5, L6: Length; W: Width.

Claims

1. A diamond sensor, wherein, The diamond sensor includes: Diamond possesses color centers with electron spin; and The sensor head houses the diamond. The diamond includes: A reflective surface that reflects excitation light that propagates through the optical system and enters the interior of the diamond; and A flat surface is provided so that the excitation light enters the interior of the diamond, and the emitted light from the color center exits from the diamond. The reflective surface reflects the emitted light from the color center after being excited by the excitation light, thus focusing the light towards the optical system. The angle formed by a specific low-index crystal plane of the diamond, i.e., the first deviation angle, relative to a reference plane perpendicular to a predetermined reference direction fixed to the sensor head, is less than 3°. The surface roughness Ra of the flat surface is less than 20 nm.

2. A diamond sensor, wherein, The diamond sensor includes: Diamond possesses color centers with electron spin; and The sensor head houses the diamond. The diamond includes: The incident surface allows the excitation light propagating through the optical system to enter the interior of the diamond; A reflecting surface that reflects the emitted light from the color center after being excited by the excitation light incident from the incident surface, focusing the light in a direction that guides it to the light-receiving optical system of the light-receiving element; and A flat surface allows the emitted light to exit from the diamond. The area of ​​the reflecting surface is larger than the area of ​​the incident surface. The reflective surface guides the emitted light, which is emitted from the same position in different directions, to the light-receiving optical system through multiple optical paths. The first deviation angle, relative to a reference plane perpendicular to a predetermined reference direction fixed to the sensor head, is less than 3°, formed by the specific crystal orientation of the diamond with a low index. The surface roughness Ra of both the flat surface and the incident surface is below 20 nm.

3. The diamond sensor according to claim 1, wherein, The diamond is in the shape of a triangular pyramid. The flat surface is the base of the triangular pyramid. The angle between the crystal facet {100} or crystal facet {111} of the diamond and the bottom surface, i.e., the second deviation angle, is less than 3°.

4. The diamond sensor according to claim 2, wherein, The diamond is in the shape of a truncated triangular pyramid. The flat surface is the bottom surface that serves as the lower base of the truncated triangular pyramid. The angle between the crystal facet {100} or crystal facet {111} of the diamond and the bottom surface, i.e., the second deviation angle, is less than 3°.

5. The diamond sensor according to claim 1 or 3, wherein, The sensor head has a sensing surface. The diamond is in the shape of a triangular pyramid. The angle between the sensing surface and the base of the triangular pyramid, i.e., the third deviation angle, is less than 1°.

6. The diamond sensor according to claim 3 or 4, wherein, The fourth deviation angle is less than 3°. When the second deviation angle is the angle between the crystal facet (001) of the diamond and the bottom surface, the fourth deviation angle is the angle between any side of the bottom surface and the <100> direction of the diamond. When the second deviation angle is the angle between the crystal face (111) of the diamond and the bottom surface, the fourth deviation angle is the angle between any side of the bottom surface and the <1-10> direction of the diamond.

7. The diamond sensor according to claim 5, wherein, The fifth deviation angle, which is the angle formed by one side of the sensing surface and any side of the bottom surface of the diamond, is less than 1°.

8. The diamond sensor according to claim 1, wherein, The diamond is the shape obtained by removing the vertices of the base of a triangle in a triangular pyramid. An angle of 80° or more and less than 100° is formed relative to the bottom surface by cutting off the first side surface formed by the vertex. The exterior angles of the hexagon formed by cutting off the vertices are greater than 57° and less than 63°.

9. The diamond sensor according to claim 2, wherein, The diamond is the shape obtained by removing the vertices of the base triangle of a triangular pyramid. An angle of 80° or more and less than 100° is formed relative to the bottom surface by cutting off the first side surface formed by the vertex. The exterior angles of the hexagon formed by cutting off the vertices are greater than 57° and less than 63°.

10. The diamond sensor according to any one of claims 1 to 9, wherein, The first deviation angle is less than 1°.

11. The diamond sensor according to claim 10, wherein, The first deviation angle is less than 0.1°.

12. The diamond sensor according to any one of claims 3, 4, 6, and 7, wherein, The second deviation angle is less than 1°.

13. The diamond sensor according to claim 12, wherein, The second deviation angle is less than 0.1°.

14. The diamond sensor according to claim 6, wherein, The fourth deviation angle is less than 1°.

15. The diamond sensor according to claim 5, wherein, The third deviation angle is less than 0.1°.

16. The diamond sensor according to claim 7, wherein, The fifth deviation angle is less than 0.1°.

17. The diamond sensor according to claim 8 or 9, wherein, The exterior angle of the hexagon is greater than 59° and less than 61°.

18. The diamond sensor according to any one of claims 8, 9, and 17, wherein, The maximum span length of the first side is 50 μm or more, and is less than 40% of the length of one side of the triangle.

19. The diamond sensor according to any one of claims 8, 9, 17, and 18, wherein, The diamond also includes a second side surface formed by cutting off each side of the bottom surface.

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