Patent Description:
In Optically Detected Magnetic Resonance (ODMR), a medium that has sublevels and an optical transition level as energy level is simultaneously irradiated with a high-frequency magnetic field (microwave) and light, and thereby a population change or the like due to magnetic resonance between the sublevels is detected as an optical signal with high sensitivity.

In general, after an electron in a ground state is excited with green light, the electron emits red light when returning the ground state. Contrarily, for example, when an electron is irradiated with a high-frequency magnetic field of about <NUM> in a nitrogen and a lattice defect in a diamond structure (NVC: Nitrogen Vacancy Center), the electron moves from the lowest level (ms = <NUM>) among three sublevels of the ground state to an energy level (ms = +<NUM> or -<NUM>) higher than the lowest level among the three sublevels. When the electron in such state is irradiated with green light, an emitting light intensity is decreased because of no radiation transition to the lowest level (ms = <NUM>) among the three levels of the ground level; and therefore, it can be determined by detecting this light whether magnetic resonance occurs due to the high-frequency magnetic field. As mentioned, in ODMR, optically detected magnetic resonance material such as NVC is used.

In a measurement system, a split-ring resonator or an antenna of a coil or wire type is arranged under a diamond sample, and the resonator or the like irradiates the sample with a high-frequency magnetic field in a microwave range of about <NUM>, and while the high-frequency magnetic field and the exciting light are swept, a detection device detects a position at which the red light from an electron decreases and thereby information on a cell near the aforementioned diamond structure is acquired (for example, see NON-PATENT LITERATURE #<NUM>).

Further, a magnetic measurement device performs magnetic measurement based on ODMR using electron spin resonance (for example, see PATENT LITERATURE #<NUM>). In this magnetic measurement device, as well, a magnetic field as micro wave is generated with only one coil.

Furthermore, document <CIT>, the article by <NPL>, and the article by <NPL>, each disclose a high-frequency magnetic field generating device which includes two coils arranged with a predetermined gap in parallel with each other, the two coils being configured for arranging electron spin resonance material in between or at one side from of the two coils; a high-frequency power supply that generates microwave current that flows in the two coils; and a transmission line part connected to the two coils, that sets a current distribution so as to locate the two coils at positions other than a node of a stationary wave.

However, the aforementioned coil or antenna is capable of generating a three-dimensional uniform high-frequency magnetic field only in a very narrow range, and therefore high detection sensitivity of ODMR is hardly achieved. For example, in case of NON-PATENT LITERATURE #<NUM>, as shown in <FIG>, a ring-antenna resonator is used that is a circular copper plate with a radius R (about <NUM>), and a slit is formed at the center of the plate and further a penetrating hole with a radius r (about <NUM>) is formed at a tip of the slit. A high-frequency power supply provides current with about <NUM> to the resonator, and thereby, as shown in <FIG>, although a uniform magnetic field is generated at an area within a <NUM>-mm radius from the center, the magnetic field intensity gradually decreases along a radius direction from the center of the coil in the other area, i.e. that is <NUM> percent of the area of the copper plate; and therefore, this area can not be used for the detection based on ODMR. It should be noted that the same problem arises in another measurement using electron spin resonance such as Electrically Detected Magnetic Resonance (EDMR).

It is an object of the present invention to provide a high-frequency magnetic field generating device that generates a substantially uniform high-frequency magnetic field in a wide three dimensional range and improves detection sensitivity in measurement based on electron spin resonance. The object is solved by the features of independent claim <NUM>. The dependent claims are directed to preferred embodiments of the invention.

The present invention provides a high-frequency magnetic field generating device that generates a substantially uniform high-frequency magnetic field in a wide three dimensional range and improves detection sensitivity in measurement based on electron spin resonance.

These and other objects, features and advantages of the present disclosure will become more apparent upon reading of the following detailed description along with the accompanied drawings.

Hereinafter, embodiments according to aspects of the present invention will be explained with reference to drawings.

<FIG> shows a perspective view diagram that explains an arrangement of coils in a high-frequency magnetic field generating device in an embodiment of the present invention.

The high-frequency magnetic field generating device according to the present invention includes at least two coils L1 and L2. As shown in <FIG>, the two coils L1 and L2 are arranged with a predetermined gap (e.g. substantially equal to a diameter of the coils L1 and L2) in parallel with each other. Further, a sample <NUM> is arranged on a plate member <NUM> such as diamond that includes an NVC as Optically Detected Magnetic Resonance material (hereinafter, called ODMR material), and the plate member <NUM> is fixed on a sample plate <NUM>. Furthermore, the two coils L1 and L2 are arranged such that the plate member <NUM> including an NVC as the ODMR material is arranged in between the two coils L1 and L2. The ODMR material is a sort of electron spin resonance material.

The two coils L1 and L2 have identical shapes to each other, and are arranged so as to have identical central axes to each other. Here, the number of turns of each coil L1 or L2 is set as substantially one turn (less than one turn). In the two coils L1 and L2, microwave current flows, and the two coils L1 and L2 generate alternate magnetic fields as microwaves in phase with each other (i.e. toward identical directions to each other at each time point) , respectively. The alternate magnetic fields are applied to the ODMR material, and in addition to the alternate magnetic fields generated by the coils L1 and L2, a static magnetic field (not shown) is applied to the ODMR material. Further, using an optical system (not shown), the ODMR material is irradiated with a measurement light such as laser light beam of a predetermined wavelength, and a measurement based on Optically Detected Magnetic Resonance (e.g. magnetic measurement, orientation measurement of an NVC, temperature measurement of an NVC or the like) is performed, for example, by observing radiant light having a specific wavelength.

<FIG> shows a circuit diagram that indicates a configuration of a high-frequency magnetic field generating device in Embodiment <NUM> of the present invention.

As shown in <FIG>, the high-frequency magnetic field generating device in Embodiment <NUM> and according to the invention further includes a high-frequency power supply <NUM>, and two line units S1 and S2.

The high-frequency power supply <NUM> generates microwave current that flows in the two coils L1 and L2. Specifically, the high-frequency power supply <NUM> generates the microwave current in a frequency band required for the Optically Detected Magnetic Resonance (here, about <NUM>).

The two line units S1 and S2 form a transmission line part respectively connected to the two coils L1 and L2, and set a current distribution so as to locate the two coils L1 and L2 at positions other than a node of a stationary wave.

Each of the line units S1 and S2 may be formed as one conductive wire line or as a distributed constant circuit including a resistor element, a condenser element and/or the like.

Specifically, in Embodiment <NUM>, as shown in <FIG>, one-side ends of the two line units S1 and S2 are open-circuited, and other-side ends of the two line units S1 and S2 are connected to one-side ends of the two coils L1 and L2, respectively. Further, other-side ends of the two coils L1 and L2 are electrically connected to each other, and the high-frequency power supply <NUM> is connected to a connecting point between the other-side ends of the two coils L1 and L2. Therefore, microwave current flows from the high-frequency power supply <NUM> into the other-side ends of the two coils L1 and L2. The two coils L1 and L2 have identical shapes to each other, and the line units S1 and S2 also have identical shapes to each other. Consequently, in view from the high-frequency power supply <NUM>, (a) the coil L1 and the line unit S1 and (b) the coil L2 and the line unit S2 have identical high frequency characteristics (i.e. identical electrical lengths) to each other.

For example, if both (a) an electrical length of the coil L1 and the line unit S1 and (b) an electrical length of the coil L2 and the line unit S2 are LAMBDA/<NUM> (LAMBDA: wavelength of the microwave), then a current distribution as shown in <FIG> appears, and the coils L1 and L2 are not located at any nodes of a stationary wave but located near antinodes of a stationary wave; and consequently, sufficient microwave current flows in the coils L1 and L2 and induces a magnetic field as a microwave.

For example, if the high-frequency power supply <NUM> generates a microwave of <NUM>, then the wavelength is about <NUM>, and therefore, the electrical length of the coil L1 and the line unit S1 and the electrical length of the coil L2 and the line unit S2 are set as about <NUM>. In addition, for easy tuning, it is favorable that lengths of the coils L1 and L2 are set to be shorter than a half of lengths of the line units S1 and S2.

The following part explains a behavior of the high-frequency magnetic field generating device in Embodiment <NUM>.

When the high-frequency power supply <NUM> generates a microwave as alternate power, microwave current flows into (a) the coil L1 and the line unit S1 and (b) the coil L2 and the line unit S2. Here, since the impedance is matched for the whole circuit, there is no need to use an impedance matching unit separately at a terminal end of (a) the coil L1 and the line unit S1 and at a terminal end of (b) the coil L2 and the line unit S2, and a stationary wave as shown in <FIG> is formed in (a) the coil L1 and the line unit S1 and (b) the coil L2 and the line unit S2.

Consequently, in the coils L1 and L2, alternate current flows with identical amplitude to each other in phase with each other. A magnetic field as microwave is formed by the current that flows in the coils L1 and L2. Further, the coils L1 and L2 are arranged coaxially and substantially in parallel with each other, and therefore, in a space between the coil L1 and the coil L2, a direction of the magnetic field is substantially in parallel with a central axis of the coils L1 and L2 and the magnetic field is substantially uniform.

As mentioned, in Embodiment <NUM>, the two coils L1 and L2 are arranged with a predetermined gap in parallel with each other and in between the two coils L1 and L2 electron spin resonance material is arranged. The high-frequency power supply <NUM> generates microwave current that flows in the two coils L1 and L2. The two line units S1 and S2 are connected to the two coils L1 and L2, respectively, and set a current distribution so as to locate the two coils L1 and L2 at positions other than a node of a stationary wave.

Consequently, a substantially uniform high-frequency magnetic field is generated in a wide three dimensional range in between the coils L1 and L2. Consequently, detection sensitivity of ODMR can be improved.

In this embodiment, the one-side ends of the line units S1 and S2 are open-circuited. Alternatively, for example, high impedance circuits having a high impedance sufficiently for a frequency of the microwave current (i.e. oscillation frequency of the power supply) may be connected to these open-circuited one-side ends and a ground.

Further, as shown in <FIG>, the two coils L1 and L2 are arranged with a predetermined gap in parallel with each other such that ODMR material is arranged in between the two coils L1 and L2. Alternatively, both of the two coils L1 and L2 may be arranged at one side from the electron spin resonance material. In such a case, although resonance band width gets a little narrow, arrangement position of the ODMR material gets high flexibility.

Furthermore, in <FIG>, the plate member <NUM> and the sample plate <NUM> are arranged to be perpendicular to the direction of the magnetic field (i.e. the direction of the central axis of the coils L1 and L2). Alternatively, the plate member <NUM> and the sample plate <NUM> may be arranged to be slanted to the direction of the magnetic field (i.e. the direction of the central axis of the coils L1 and L2). Even in such a case, the uniform magnetic field is applied to the plate member <NUM>.

<FIG> shows a circuit diagram that indicates a configuration of a high-frequency magnetic field generating device in Embodiment <NUM> of the present invention. The high-frequency magnetic field generating device in Embodiment <NUM> has the same configuration as the configuration of the high-frequency magnetic field generating device in Embodiment <NUM>, and additionally includes an impedance matching unit <NUM> in between the high-frequency power supply <NUM> and the two coils L1 and L2.

If impedance matching is not achieved in between the high-frequency power supply <NUM> and the two coils L1 and L2, then a microwave from the high-frequency power supply <NUM> reflects at the coils L1 and L2, and consequently adequate microwave current does not flow into the coils L1 and L2. Therefore, if impedance matching is not achieved in between the high-frequency power supply <NUM> and the two coils L1 and L2, then the impedance matching unit <NUM> is installed. Consequently, the impedance matching is achieved and the microwave from the high-frequency power supply <NUM> propagates into the coils L1 and L2. As the impedance matching unit <NUM>, for example, a resistance element (R), a capacitance element (C), an inductance element (L) or a combination thereof is used.

In <FIG>, the impedance matching unit <NUM> is installed in between the high-frequency power supply <NUM> and a connecting point between the coils L1 and L2. Alternatively, two impedance matching units <NUM> may be installed (a) in between the high-frequency power supply <NUM> and the coil L1 and (b) in between the high-frequency power supply <NUM> and the coil L2, respectively.

Further, in a high-frequency magnetic field generating device in another embodiment mentioned below, the same impedance matching unit(s) may be installed as well. If the high-frequency power supply <NUM> is connected to two line units in another embodiment, the impedance matching unit(s) may be installed in between the high-frequency power supply <NUM> and the two line units in the same manner.

As mentioned, in Embodiment <NUM>, even when the impedance matching is not achieved with only the coils L1 and L2 and the line units S1 and S2, the impedance matching can be achieved by the impedance matching unit <NUM>.

<FIG> shows a circuit diagram that indicates a configuration of a high-frequency magnetic field generating device in Embodiment <NUM> of the present invention. The high-frequency magnetic field generating device in Embodiment <NUM> includes at least two pairs of coils (L1-i, L2-i) (i= <NUM>,. , n; n > <NUM>) and at least two line units Sl-j, S2-j that include (a) a line unit S1-j in between (a1) one coil L1-i in one pair among the at least two pairs and (a2) one coil L1-i in the other pair among the at least two pairs and (b) a line unit S2-j in between (b1) the other coil L2-i in the one pair among the at least two pairs and (b2) the other coil L2-i in the other pair among the at least two pairs.

In Embodiment <NUM>, the high-frequency power supply <NUM> generates microwave current that flows two coils L1-i and L2-i that form each pair among the aforementioned at least two pairs of coils (L1-i, L2-i).

The two coils that form each pair among the aforementioned at least two pairs of coils (L1-i, L2-i) are arranged with a predetermined gap in parallel with each other, and electron spin resonance material is arranged in between these two coils. For example, the coils L1-<NUM> to L1-n are arranged such that the magnetic fields induced by the coils L1-<NUM> to L1-n gets in phase with each other, and the coils L2-<NUM> to L2 -n are arranged such that the magnetic fields induced by the coils L2-<NUM> to L2-n gets in phase with each other. Thus, the magnetic fields induced by the coils L1-<NUM> to L1-n and L2-<NUM> to L2-n have identical directions to each other.

Further, the aforementioned at least two line units S1-j and S2-j as a transmission line unit set a current distribution so as to locate the coils L1-i and L2-i in the at least two pairs at positions other than a node of a stationary wave. For example, all of the line units S1-j and S2-j have identical electric lengths with each other, the line units S1-j and the coils L1-j are alternately arranged, and the line units S2-j and the coils L2-j are alternately arranged. Specifically, the line unit S1-j is arranged in between the coil L1-j and the coil L1-(j+<NUM>), the line unit S2-j is arranged in between the coil L2-j and the coil L2-(j+<NUM>), and a terminal end of the line unit S1-n and a terminal end of the line unit S2-n are open-circuited.

For example, the coils L1-i and L2-i have identical shapes to each other and are arranged so as to have identical central axes to each other. Here, the number of turns of each coil L1-i or L2-i is set as substantially one turn (less than one turn); and if both (a) an electrical length of the coils L1-<NUM> to L1-n and the line unit(s) S1-j therebetween and (b) an electrical length of the coil L2-<NUM> to L2-n and the line unit(s) S2-j therebetween are (2n - <NUM>)*LAMBDA/<NUM>, then a current distribution as shown in <FIG> appears, and all of the coils L1-i and L2-i are located at positions other than any nodes of a stationary wave; and consequently, sufficient microwave current flows in the coils L1-i and L2-i and induces a magnetic field as a microwave.

As mentioned, in Embodiment <NUM>, a large number of the coils L1-i and L2-i are installed. Consequently, the induced high-frequency magnetic field gets a high intensity.

<FIG> shows a circuit diagram that indicates a configuration of a high-frequency magnetic field generating device of an Example <NUM> not covered by the invention. As shown in <FIG>, the high-frequency magnetic field generating device in Example <NUM> includes two pairs of coils (L11, L21) and (L12, L22), and two line units S11 and S21 as a transmission line part.

<FIG> shows a perspective view diagram that explains an example of an arrangement of the coils L11, L12, L21 and L22 in a high-frequency magnetic field generating device in Example <NUM>. As shown in <FIG>, the number of turns of each coils L11, L21, L12 or L22 is substantially a half of one turn; and the coil L11 and the coil L22 form a pair and induce magnetic fields as microwave in phase with each other, and the coil L12 and the coil L21 form a pair and induce magnetic fields as microwave in phase with each other.

Alternatively, the number of turns of each coils L11, L21, L12 or L22 may be substantially one turn as well as in Embodiment <NUM>, <NUM> or <NUM>; and the in-phase coils L11 and L22 may be arranged contiguously to each other (i.e. so as to cause the number of turns to get substantially two turns in total), and the in-phase coils L12 and L21 may be arranged contiguously to each other.

Further, in Example <NUM>, (a) one-side ends of the two coils L12 and L22 are connected to a ground, (b) other-side ends of the two coils L12 and L22 are connected to one-side ends of the two line units S11 and S21, (c) other-side ends of the two line units S11 and S21 are connected to one-side ends of the two coils L11 and L21, (d) other-side ends of the two coils L11 and L21 are connected to each other, and (e) the high-frequency power supply <NUM> is connected to a connecting position between the two coils L11 and L21. Microwave current flows from the high-frequency power supply <NUM> through the coils L11 and L21 into the other-side ends of the two line units S11 and S21. Therefore, antinodes of the current distribution are located at ends (i.e. short-circuited ends) of the coils L12 and L22, and as shown in <FIG>, each of the coils L11, L12, L21 and L22 is located at a position other than a node of the current distribution.

<FIG> shows a perspective view diagram that explains an example of an arrangement of coils and line units in a high-frequency magnetic field generating device in Embodiment <NUM> of the present invention.

The high-frequency magnetic field generating device in Embodiment <NUM> has a circuit configuration as described in Embodiment <NUM> or <NUM> (i.e. <FIG> or <FIG>), and includes a circuit board <NUM>. The two coils L1 and L2 are arranged on one surface of the circuit board <NUM> so as to be substantially perpendicular to this surface. Further, in Embodiment <NUM>, the two line units S1 and S2 are line members that have partially-cutted-off ring shapes and are arranged on the other surface of the circuit board <NUM> so as to be substantially perpendicular to this surface.

Furthermore, in the manner shown in <FIG> or <FIG>, the coils L1 and L2, the line units S1 and S2, and the high-frequency power supply <NUM> are electrically connected, and these electrical connections are established with a wiring pattern on the circuit board <NUM>, a through hole in the circuit board <NUM>, and/or the like.

Behaviors of the high-frequency magnetic field generating device in Embodiment <NUM> are identical or similar to those in Embodiment <NUM> or <NUM>, and therefore not explained here.

The high-frequency magnetic field generating device in Embodiment <NUM> has a circuit configuration as described in Embodiment <NUM> or <NUM> (i.e. <FIG> or <FIG>), and includes a circuit board <NUM>. The two coils L1 and L2 are arranged on one surface of the circuit board <NUM> so as to be substantially perpendicular to this surface. Further, in Embodiment <NUM>, the two line units S1 and S2 are wiring patterns, respectively, and are formed on any surface of the circuit board <NUM>.

<FIG> shows a perspective view diagram that explains another example of line units in a high-frequency magnetic field generating device in Embodiment <NUM> of the present invention. As shown in <FIG>, branch parts <NUM> and <NUM> identical to each other are formed in the line units S1 and S2, respectively. Consequently, using the branch parts <NUM> and <NUM>, the current distribution can be adjusted in the coils L1 and L2 and the line units S1 and S2, and in addition, a width of input frequency band can be adjusted.

<FIG> shows a perspective view diagram that explains an example of an arrangement of coils and line units in a high-frequency magnetic field generating device in Example <NUM> not covered by the invention.

The high-frequency magnetic field generating device in Example <NUM> has a circuit configuration as described in Example <NUM> (i.e. <FIG>), and includes a circuit board <NUM>. As shown in <FIG>, in Example <NUM>, the coils L11, L12, L21 and L22 are arranged on the circuit board <NUM> so as to be perpendicular to the circuit board <NUM>, the line unit S11 that has a partially-cutted-off ring shape is connected to an end of the coil L11 and an end of the coil L12, and the line unit S21 that has a partially-cutted-off ring shape is connected to an end of the coil L21 and an end of the coil L22.

As shown in <FIG>, the line units S11 and S21 are arranged so as to be perpendicular to an opening direction of the coils L11 and L22 and an opening direction of the coils L12 and L21 (i.e. a direction of a magnetic field formed by the coils L11, L22, L12 and L21), such that magnetic coupling is restrained between (a) the coils L11, L22, L12 and L21 and (b) the line units S11 and S2.

Behaviors of the high-frequency magnetic field generating device in Example <NUM> are identical or similar to those in Example <NUM>, and therefore not explained here.

<FIG> shows a circuit diagram that indicates a configuration of a high-frequency magnetic field generating device in Example <NUM> not covered by the invention.

In the high-frequency magnetic field generating device in Example <NUM>, as shown in <FIG>, the two coils L1 and L2 are connected in parallel with each other, and one transmission line S1s as a transmission line part is connected to a connecting point between the two coils L1 and L2. In Example <NUM>, the one transmission line S1s sets a current distribution so as to locate the two coils L1 and L2 at positions other than a node of a stationary wave.

Specifically, in Example <NUM>, as shown in <FIG>, one end of the line unit S1s is open-circuited, and the other end of the line unit S1s is connected to one connecting point between the two coils L1 and L2. Further, the high-frequency power supply <NUM> is connected to the other connecting point between the two coils L1 and L2. Therefore, microwave current flows from the high-frequency power supply <NUM> into the other-side ends of the two coils L1 and L2. The two coils L1 and L2 have identical shapes to each other. Consequently, in view from the high-frequency power supply <NUM>, (a) the coil L1 and the line unit S1s and (b) the coil L2 and the line unit S1s have identical high frequency characteristics (i.e. identical electrical lengths) to each other.

For example, if an electrical length of the coils L1 and L2 and the line unit S1s is LAMBDA/<NUM> (LAMBDA: wavelength of the microwave), then a current distribution as shown in <FIG> appears, and the coils L1 and L2 are not located at any nodes of a stationary wave but located near antinodes of a stationary wave; and consequently, sufficient microwave current flows in the coils L1 and L2 and induces a magnetic field as a microwave.

Behaviors of the high-frequency magnetic field generating device in Example <NUM> are identical or similar to those in Embodiment <NUM>, and therefore not explained here.

In Example <NUM>, instead of the configuration of the high-frequency magnetic field generating device shown in <FIG>, modification examples shown in <FIG> or <FIG> may be applied.

<FIG> shows a circuit diagram that indicates a configuration of a high-frequency magnetic field generating device in a modification example #<NUM> of Example <NUM> of the present invention. In the modification example #<NUM> shown in <FIG>, one end of a variable capacitance element <NUM> is connected to one end of the line unit S1s such that this one end is not connected to the coils L1 and L2, and the other end of the variable capacitance element <NUM> is connected to a ground. Consequently, even if displacement appears between the central axes, a center of a resonance frequency band of the coils L1 and L2 can be adjusted by changing a capacitance of the variable capacitance element <NUM> so as to cause the center of a resonance frequency band to get closest to a desired frequency. A very small capacitance value is sufficient of this variable capacitance element <NUM>. Therefore, the variable capacitance element <NUM> may be a device that moves a position of a part of the line unit S1s a little. Alternatively, the variable capacitance element <NUM> may be a variable capacitor that has a small capacitance, for example.

<FIG> shows a circuit diagram that indicates a configuration of a high-frequency magnetic field generating device in a modification example #<NUM> of Example <NUM> of the present invention. In the modification example #<NUM> shown in <FIG>, one end of a variable capacitance element <NUM> is connected to one-side ends (i.e. the ends on the power supply side) of the coils L1 and L2 such that the one-side ends are not connected to the line unit S1s, and the other end of the variable capacitance element <NUM> is connected to a ground. Consequently, as well as the aforementioned modification example #<NUM>, even if shapes of the coils L1 and L2 change or displacement occurs between the central axes, a center of a resonance frequency band of the coils L1 and L2 can be adjusted by changing a capacitance of the variable capacitance element <NUM> so as to cause the center of a resonance frequency band to get closest to a desired frequency. A very small capacitance value is sufficient of this variable capacitance element <NUM>. Therefore, the variable capacitance element <NUM> may be (a) a variable capacitor that has a small capacitance, for example, (b) a device that moves a part of a conductive line between the power supply and the coils L1 and L2, or the like.

Specifically, in Example <NUM>, as shown in <FIG>, one end of the line unit S1s is connected through a first impedance matching unit <NUM> to the high-frequency power supply <NUM>, and the other end of the line unit S1s is connected to one connecting point between the two coils L1 and L2. Further, one end of a second impedance matching unit <NUM> is connected to the other connecting point between the two coils L1 and L2. The other end of the second impedance matching unit <NUM> is open-circuited. Therefore, microwave current flows from the high-frequency power supply <NUM> through the first impedance matching unit <NUM> and the line unit S1s to the ends of the two coils L1 and L2. The two coils L1 and L2 have identical shapes to each other. Consequently, in view from the high-frequency power supply <NUM>, (a) the coil L1 and the line unit S1s and (b) the coil L2 and the line unit S1s have identical high frequency characteristics (i.e. identical electrical lengths) to each other.

In the high-frequency magnetic field generating device in Example <NUM>, as shown in <FIG>, the two coils L1 and L2 are connected in parallel with each other, and transmission lines S1s as a transmission line part are connected to connecting points between the two coils L1 and L2, respectively. In Embodiment <NUM>, the transmission lines S1s set a current distribution so as to locate the two coils L1 and L2 at positions other than a node of a stationary wave.

Specifically, in Example <NUM>, as shown in <FIG>, one end of the first line unit S1s is connected through a first impedance matching unit <NUM> to the high-frequency power supply <NUM>, and the other end of the first line unit S1s is connected to one connecting point between the two coils L1 and L2. Further, one end of a second line unit S1s is connected to the other connecting point between the two coils L1 and L2. The other end of the second line unit S1s is connected to one end of a second impedance matching unit <NUM>. The other end of the second impedance matching unit <NUM> is open-circuited. Therefore, microwave current flows from the high-frequency power supply <NUM> through the first impedance matching unit <NUM> and the first line unit S1s to the ends of the two coils L1 and L2. The two coils L1 and L2 have identical shapes to each other, and the line units S1s also have identical shapes to each other. Consequently, in view from the high-frequency power supply <NUM>, (a) the coil L1 and the line units S1s and (b) the coil L2 and the line units S1s have identical high frequency characteristics (i.e. identical electrical lengths) to each other.

For example, if an electrical length of the coils L1 and L2 and the line units S1s is LAMBDA/<NUM> (LAMBDA: wavelength of the microwave), then a current distribution as shown in <FIG> appears, and the coils L1 and L2 are not located at any nodes of a stationary wave but located near antinodes of a stationary wave; and consequently, sufficient microwave current flows in the coils L1 and L2 and induces a magnetic field as a microwave.

<FIG> shows a diagram that indicates a configuration of a high-frequency magnetic field generating device in Embodiment <NUM> of the present invention.

In Embodiment <NUM>, the coils L1 and L2 are formed as metal patterns in parallel with each other on a front surface and a back surface of a circuit board <NUM> that has a predetermined thickness. Further, a penetrating hole <NUM> is formed so as to penetrate a center of the coils L1 and L2. This penetrating hole <NUM> enables the high-frequency alternate magnetic field to be applied to a sample not only (a) in a case that a pair of the coil L1 and L2 is arranged at one side from the sample with a predetermined distance but (b) in a case that the sample is arranged at any position between the coils L1 and L2 in the height direction.

Further, as shown in <FIG>, penetrating holes <NUM> and <NUM> may be formed in the wall thickness of the circuit board <NUM> so as to be parallel to a radius direction of the coils L1 and L2. In such a case, a laser beam enters from the penetrating hole <NUM>, a sample (not shown) in the penetrating hole <NUM> is irradiated with the laser beam, and reflection light thereof passes through the penetrating hole <NUM> in an upward direction and/or a downward direction. Therefore, this reflection light can be detected by a microscope. Further, a part of the laser light beam passes through the sample and the part of the laser light beam exits through the penetrating hole <NUM>. Therefore, the exiting part of the laser light beam may be observed. With talking refraction of the light beam into account, a diameter of the penetrating hole <NUM> may be larger than a diameter of the penetrating hole <NUM>.

In Embodiment <NUM>, the circuit board <NUM> is arranged in between the coils L1 and L2 in parallel, and therefore, an advantageous mechanical characteristic and an advantageous electrical characteristic are obtained from various viewpoints such as stable forming of shapes of the coils L1 and L2 and keeping a stable distance between the coils L1 and L2.

<FIG> shows a diagram that indicates a configuration of a high-frequency magnetic field generating device in Example <NUM> not covered by the invention.

In Example <NUM>, the high-frequency magnetic field generating device includes a plate coil La instead of the aforementioned coils L1 and L2 described in Embodiment <NUM>. A penetrating hole <NUM> is formed in a circuit board <NUM> that has a predetermined thickness. The plate coil La is arranged in the penetrating hole <NUM>. In Embodiment <NUM>, the plate coil La is fixed on an inner wall facing the penetrating hole <NUM> of the circuit board <NUM> such that a longitudinal direction of a cross section of the plate coil La is perpendicular to the circuit board <NUM>. The cross section of the plate coil La has a substantially rectangle shape. The penetrating hole <NUM> may be a through hole; and the plate coil La may be a member formed by flexing and/or bending a thin metal plate such as copper plate or may be a metal foil formed on an inner circumferential surface of the through hole as the penetrating hole <NUM> using metal plating or the like.

Further, in Example <NUM>, the penetrating hole <NUM> includes an observation hole part 82a of which a cross section has a circular shape. Among four edge line parts LaEU and LaEL (in particular, edge line parts in the observation hole part 82a) of the plate coil La, (a) one of edge line parts LaEU in a top end side and (b) one of edge line parts LaEL in a bottom end side act as two coils arranged with a predetermined gap in parallel with each other, and these two coils are arranged (a) in between which electron spin resonance material is arranged or (b) arranged at one side from electron spin resonance material. The current intensively flows at the edge line parts LaEU and LaEL of the plate coil La due to skin effect in high frequency (in particular, equal to or higher than MHz order), and therefore, the edge line part LaEU in the top end side and the edge line part LaEL in the bottom end side substantially act as individual coils. It is favorable that a height of the plate coil La (i.e. a length of a long side of the cross section) is set to be substantially equal to a radius of a circular part of the plate coil La. Further, in order to restrain stray capacitance between the plate coil La and a lens barrel of the microscope, it is favorable that a width of the plate coil La (i.e. a length of a short side of the cross section) is set to be sufficiently smaller than the height of the plate coil La.

This penetrating hole <NUM> enables the high-frequency alternate magnetic field to be applied to a sample not only (a) in a case that both of the edge line part LaEU in the top end side and the edge line part LaEL in the bottom end side are arranged at one side from the sample with a predetermined distance but (b) in a case that the sample is arranged at any position between the edge line part LaEU in the top end side and the edge line part LaEL in the bottom end side in the height direction.

Further, as shown in <FIG>, penetrating holes <NUM> and <NUM> may be formed in the wall thickness of the circuit board <NUM> so as to be parallel to a radius direction of the circular part of the plate coil La, and penetrating holes 85a and 85b of the plate coil La may be formed at positions on an extension line between the penetrating holes <NUM> and <NUM>. In such a case, a laser beam enters from the penetrating holes <NUM> and 85a, a sample (not shown) in the penetrating hole <NUM> is irradiated with the laser beam, and reflection light thereof passes through the penetrating hole <NUM> in an upward direction and/or a downward direction. Therefore, this reflection light can be detected by a microscope. Further, a part of the laser light beam passes through the sample and the part of the laser light beam exits through the penetrating holes 85b and <NUM>. Therefore, the exiting part of the laser light beam may be observed. With talking refraction of the light beam into account, diameters of the penetrating holes 85a and <NUM> may be larger than diameters of the penetrating holes <NUM> and 85a.

Other parts of configuration and behaviors of the high-frequency magnetic field generating device in Example 6are identical or similar to those in Example <NUM> or embodiment <NUM> or a combination thereof, and therefore not explained here.

As mentioned, in Example <NUM>, the aforementioned plate coil La is applied and thereby a direct-current resistance of the coil gets low. If there is a metallic object such as a housing of the microscope for observation or a dielectric object such as sample base around the coil, then the resonance frequency may change due to the existence of such object, but such change of the resonance frequency is restrained by applying the aforementioned plate coil La.

For example, when the thickness of the circuit board was <NUM> and a radius of the circular part of the plate coil La was <NUM>, the resonance frequency in Embodiment <NUM> was <NUM> in a status that a sample was arranged in the penetrating hole <NUM> or <NUM> in a status that a lens of the microscope was arranged at the distance of <NUM>. Contrarily, in a comparative example, the resonance frequency was <NUM> in a status that a sample was arranged in the penetrating hole or <NUM> in a status that a lens of the microscope was arranged at the distance of <NUM>. Thus, the change of the resonance frequency is restrained.

In Example <NUM>, the penetrating hole <NUM> has a substantially rectangular shape, and the plate coil La is arranged in the penetrating hole <NUM>.

In Example <NUM>, the plate coil La is fixed such that the plate coil La protrudes from an inner wall facing the penetrating hole <NUM> of the circuit board <NUM>.

Other parts of configuration and behaviors of the high-frequency magnetic field generating device in Example <NUM> are identical or similar to those in Example <NUM>, and therefore not explained here.

Further, in Example <NUM>, the coils L11 and L21 may be removed and the line units S11 and S21 may be connected to each other, and the high-frequency power supply <NUM> may be connected to a connecting point between the line units S11 and S21.

Furthermore, in any of the aforementioned embodiments, the line unit is used as the transmission line unit. Alternatively, the aforementioned line unit may be replaced with a lumped constant circuit if required.

Furthermore, in any of the aforementioned embodiments, a diamond including an NVC is described as an example of the ODMR material. Alternatively, the ODMR material including another color center (e.g. SiC color center or color center of ZnO, GaN, Si, an organic substance or the like) may be used. In such a case, the high-frequency power supply <NUM> generates microwave current having a frequency corresponding to the color center in use.

Furthermore, in any of the aforementioned embodiments, the high-frequency magnetic field generating device can form a uniform magnetic field in an area substantially identical to an opening area of the coil. Therefore, in particular, the high-frequency magnetic field generating device is applied to ODMR in a high frequency range equal to or higher than <NUM>, and in addition, the high-frequency magnetic field generating device may be applied to another measurement using electron spin resonance, such as EDMR. <FIG> shows a diagram that indicates a result of a simulation of a magnetic field emitted from the high-frequency magnetic field generating device in Embodiment <NUM> of the present invention. This simulation is performed under a condition that current of about <NUM> is supplied from a power supply to the coil L1 and L2, and the result shows that as shown in <FIG>, a uniform magnetic field (for example, a magnetic field area that has an error of <NUM> percent or less of the value of the magnetic field intensity at the center) are generated in a substantially whole area of the opening area from the center of the circular part of the coils L1 and L2.

Further, even in a range less than <NUM>, a high-frequency magnetic field generating device in each embodiment of the present invention can be used as well as an ordinary coil-type resonator.

Claim 1:
A high-frequency magnetic field generating device for electron spin resonance, comprising:
two coils (L1, L2, L11, L12, L21, L22) arranged with a predetermined gap in parallel with each other, an electron spin resonance material being arranged in between or at one side of the two coils (L1, L2, L11, L12, L21, L22);
a high-frequency power supply (<NUM>) configured to generate a microwave current that flows in the two coils (L1, L2, L11, L12, L21, L22); and
a transmission line part (S1, S2, S11, S12, S21, S22, S1s) connected to the two coils (L1, L2, L11, L12, L21, L22) and configured to set a current distribution so as to locate the two coils at positions other than a node of a stationary wave of the microwave current;
wherein the transmission line part (S1, S2, S11, S12, S21, S22, S1s) is two transmission lines;
the two transmission lines are connected to the two coils (L1, L2, L11, L12, L21, L22), respectively;
one-side ends of the two transmission lines are open-circuited or are connected to a high impedance circuit for a frequency of the microwave current;
other-side ends of the two transmission lines are connected to one-side ends of the two coils; and
other-side ends of the two coils (L1, L2, L11, L12, L21, L22) are connected to each other and the high-frequency power supply (<NUM>) is connected to a connecting point between the other-side ends of the two coils such that the microwave current from the high-frequency power supply (<NUM>) flows into the other-side ends of the two coils (L1, L2, L11, L12, L21, L22).