Nuclear magnetic resonance sensing device and nuclear magnetic resonance sensing method

Abstract

A nuclear magnetic resonance sensing unit (1) of the present invention applies, to a target object, a high-frequency magnetic field based on an RF signal, and generates an observation signal having a frequency that was shifted from a frequency of the RF signal by a frequency of an NMR signal. A mixer unit (6) generates, on the basis of an LO signal, an IF demodulation signal including the NMR signal. Meanwhile, a mixer unit (8) generates a pseudo IF signal from the LO signal and the RF signal, and a phase detection unit (9) detects a specific phase in a waveform of the pseudo IF signal. In a digitization device (21), a physical field generation device (41) generates a magnetic field or the like corresponding to the IF demodulation signal that has passed through a low-pass filter (7), an optical quantum sensor unit (42) generates light corresponding to the magnetic field or the like by means of a sensing member, and an ADC (43) digitizes a sensor signal obtained from the light by photoelectric conversion. The optical quantum sensor unit (42) performs the above-described quantum operation at a timing of the detected specific phase.

Description

Nuclear magnetic resonance sensing device and nuclear magnetic resonance sensing method

[0001] The present invention relates to a nuclear magnetic resonance sensing device and a nuclear magnetic resonance sensing method.

[0002] In general, a measurement device that uses nuclear magnetic resonance applies a high-frequency magnetic field based on an RF (Radio Frequency) signal having a frequency close to the frequency of precession to a measurement object using a high-frequency coil, causing nuclear magnetization to resonate, and then detects the resonated nuclear magnetization using a receiving coil to generate an observation signal including a nuclear magnetic resonance (NMR) signal.

[0003] A nuclear magnetic resonance sensing device (a) applies a high-frequency magnetic field based on an RF signal to a target object and generates an observation signal whose frequency is shifted from the frequency of the RF signal by the frequency of the NMR signal, (b) generates an IF demodulated signal including the NMR signal using a mixer, (c) extracts low-frequency band components of the IF demodulated signal using a low-pass filter, (d) further includes a digitizing device in which a physical field generator generates a magnetic field or the like corresponding to the IF demodulated signal that has passed through the low-pass filter, (e) an optical quantum sensor unit generates light corresponding to the magnetic field or the like using a sensing element and converts the light into a sensor signal using a photoelectric element, and (f) an analog-to-digital converter digitizes the sensor signal (see, for example, Patent Document 1). This optical quantum sensor unit performs quantum operations on the sensing element to generate light corresponding to the magnetic field or the like in the sensing element.

[0004] International Publication No. 2023 / 089883

[0005] In the nuclear magnetic resonance sensing device described above, the sensitivity (such as the intensity of the light described above) changes depending on the timing at which the quantum operation is performed, so it is necessary to appropriately set the timing at which the quantum operation is performed in order to achieve good sensitivity.

[0006] The present invention has been made in consideration of the above problems, and aims to provide a nuclear magnetic resonance sensing device and a nuclear magnetic resonance sensing method in which the timing of quantum operations is appropriately set and sensing is performed with good sensitivity.

[0007] A nuclear magnetic resonance sensing device according to the present invention includes a nuclear magnetic resonance sensing unit that applies a high-frequency magnetic field based on an RF signal to a target object and generates an observation signal having a frequency shifted from the frequency of the RF signal by the frequency of the nuclear magnetic resonance signal, a first mixer that performs intermediate frequency demodulation of the observation signal based on a local oscillation signal to generate an intermediate frequency demodulated signal including the nuclear magnetic resonance signal, a low-pass filter that attenuates high-frequency band components of the intermediate frequency demodulated signal, a digitizing device that digitizes the intermediate frequency demodulated signal that has passed through the low-pass filter, a second mixer that generates a pseudo intermediate frequency signal from the local oscillation signal and the RF signal, and a phase detection unit that detects a specific phase in the waveform of the pseudo intermediate frequency signal. The digitizing device includes a physical field generator that generates a magnetic field or electric field corresponding to the intermediate frequency demodulated signal that has passed through the low-pass filter, an optical quantum sensor that generates light corresponding to the magnetic field or electric field using a sensing member and converts the light into an electrical signal as a sensor signal using a photoelectric element, and an analog-to-digital converter that digitizes the sensor signal. The optical quantum sensor unit then performs quantum operations on the sensing member at the timing of the detected specific phase, causing the sensing member to generate light corresponding to the magnetic field or electric field described above.

[0008] A nuclear magnetic resonance sensing method according to the present invention includes the steps of: applying a radio frequency magnetic field based on an RF signal to a target object and generating an observation signal having a frequency shifted from the frequency of the RF signal by the frequency of the nuclear magnetic resonance signal; performing intermediate frequency demodulation of the observation signal based on a local oscillation signal to generate an intermediate frequency demodulated signal including the nuclear magnetic resonance signal; attenuating high frequency components of the intermediate frequency demodulated signal using a low-pass filter; digitizing the intermediate frequency demodulated signal that has passed through the low-pass filter using a digitizing device; generating a pseudo intermediate frequency signal from the local oscillation signal and the RF signal; and detecting a specific phase in the waveform of the pseudo intermediate frequency signal. In the digitizing step, (a) a magnetic field or electric field corresponding to the intermediate frequency demodulated signal that has passed through the low-pass filter is generated, (b) light corresponding to the magnetic field or electric field is generated using a sensing element, (c) the light is converted into an electrical signal as a sensor signal using a photoelectric element, and (d) the sensor signal is digitized using an analog-to-digital converter. Furthermore, in the digitizing step, quantum operations are performed on the sensing element at the timing of the detected specific phase, causing the sensing element to generate recorded light corresponding to the magnetic field or electric field.

[0009] According to the present invention, it is possible to provide a nuclear magnetic resonance sensing device and a nuclear magnetic resonance sensing method in which the timing of quantum manipulation is appropriately set and sensing is performed with good sensitivity.

[0010] Fig. 1 is a block diagram showing the configuration of a nuclear magnetic resonance sensing device according to a first embodiment of the present invention. Fig. 2 is a block diagram showing the configuration of a digitizing device 21 in Fig. 1. Fig. 3 is a diagram showing the configuration of a sensor main body 51 in the digitizing device according to the first embodiment. Fig. 4 is a diagram explaining a specific phase in a pseudo IF signal. Fig. 5 is a block diagram showing the configuration of a nuclear magnetic resonance sensing device according to a second embodiment of the present invention. Fig. 6 is a block diagram showing the configuration of a nuclear magnetic resonance sensing device according to the second embodiment of the present invention.

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] Embodiment 1.

[0013] 1 is a block diagram showing the configuration of a nuclear magnetic resonance sensing device according to a first embodiment of the present invention. This nuclear magnetic resonance sensing device is used for molecular structure analysis and imaging of a target object.

[0014] The nuclear magnetic resonance sensing device shown in FIG. 1 comprises a nuclear magnetic resonance sensing unit 1, reference signal generating devices 2 and 3, a switching unit 4, a matching and tuning circuit 5, a mixer unit 6, and a low-pass filter 7.

[0015] The nuclear magnetic resonance sensing unit 1 applies an RF signal, which will be described later, to a target object, and the frequency of the RF signal is f ＲＦ to the frequency f of the nuclear magnetic resonance (NMR) signal ＮＭＲ The frequency shifted by ＲＦ +f ＮＭＲ ) observation signal (analog electrical signal).

[0016] Specifically, the nuclear magnetic resonance sensing unit 1 includes a coil 11 and a magnet unit 12. The coil 11 applies a high-frequency magnetic field based on an RF signal to the target object 101, senses magnetic field changes based on the movement of nuclear magnetization in the target object 101, and outputs an observation signal. The magnet unit 12 is a permanent magnet or an electromagnet, and applies a static magnetic field or a gradient magnetic field to the target object 101. This observation signal includes an NMR signal and has a frequency f ＮＭＲ and RF signal frequency f ＲＦ The sum of the frequency (f ＲＦ +f ＮＭＲ )

[0017] The reference signal generator 2 generates and outputs an RF signal. The reference signal generator 3 generates and outputs a local oscillation (LO) signal. The LO signal has an RF signal frequency f ＲＦ to a single intermediate frequency f ＩＦ The RF signal is branched by coupler 2a, and the LO signal is branched by splitter 3a so that the two signals have the same level after branching.

[0018] The switching unit 4 switches the connection destination of the nuclear magnetic resonance sensing unit 1 side (nuclear magnetic resonance sensing unit via the matching tuning circuit 5) from one of the RF signal transmission system (reference signal generator 2) and the observation signal reception system (reference signal generators 2 and 3, mixer unit 6, and low-pass filter 7) to the other. Specifically, when transmitting an RF signal, the switching unit 4 electrically connects the transmission system to the nuclear magnetic resonance sensing unit 1 side, and when receiving an observation signal, electrically connects the reception system to the nuclear magnetic resonance sensing unit 1 side.

[0019] The matching and tuning circuit 5 is a circuit that performs impedance matching to suppress reflection of the RF signal at the nuclear magnetic resonance sensing unit 1, and also performs frequency tuning to improve the level of the NMR signal.

[0020] The mixer unit 6 performs intermediate frequency demodulation of the observation signal based on the LO signal to generate an intermediate frequency demodulated signal (IF demodulated signal) including the nuclear magnetic resonance signal. Specifically, the mixer unit 6 mixes the observation signal and the LO signal to perform intermediate frequency (IF) demodulation, and generates two frequency components (2f ＲＦ -f ＩＦ -f ＮＭＲ ), (f ＩＦ +f ＮＭＲ For example, the mixer unit 6 is a double balanced mixer (DBM) made up of a diode and a phase distributor, and does not include any active elements such as transistors.

[0021] The low-pass filter 7 separates the two band components (2f ＲＦ -f ＩＦ -f ＮＭＲ ), (fIF+f ＮＭＲ ) of the high frequency band component (2f ＲＦ -f ＩＦ -f ＮＭＲ ) and attenuates the low-frequency component (f ＩＦ +f ＮＭＲThe low-pass filter 7 is an analog filter that is made up of only passive elements such as capacitors, inductors, and resistors.

[0022] Furthermore, the nuclear magnetic resonance sensing device shown in FIG. 1 includes a mixer unit 8 and a phase detection unit 9 .

[0023] The mixer unit 8 converts the LO signal and the RF signal into a pseudo intermediate frequency signal (frequency f ＩＦ Here, in order to suppress the delay between the IF demodulated signal and the pseudo IF signal, it is preferable that the mixer unit 8 is the same as the mixer unit 6.

[0024] The phase detector 9 detects a specific phase in the waveform of the pseudo IF signal and generates and outputs a synchronization signal indicating the specific phase. The phase detector 9 may detect the specific phase using a comparator (such as a zero-cross comparator), or may detect the specific phase by converting the pseudo IF signal into a digital signal using an analog-to-digital converter and performing signal processing on the digital signal using a DSP (Digital Signal Processor) or the like.

[0025] Furthermore, the nuclear magnetic resonance sensing device shown in FIG. 1 includes a digitizing device 21 and a control device 22 .

[0026] The digitizing device 21 digitizes the IF demodulated signal (frequency component (f ＩＦ +f ＮＭＲ )) from an analog signal to a digital signal.

[0027] The control device 22 includes a computer that operates according to a control program, and the computer includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The control program is loaded into the RAM and executed by the CPU, thereby performing the operations described below. Specifically, the control device 22 controls the nuclear magnetic resonance sensing unit 1 and the switching unit 4 to apply the above-mentioned high-frequency magnetic field to the nuclear magnetic resonance sensing unit 1 and output the above-mentioned observation signal. Furthermore, the control device 22 converts the IF demodulated signal (frequency component (f ＩＦ +f ＮＭＲ )) is input from the digitizer 21 and subjected to predetermined signal processing (frequency component f ＮＭＲ ) and extract the IF demodulated signal (frequency component (f ＩＦ +f ＮＭＲ )) from the frequency f ＮＭＲ The components (i.e., NMR signals) of

[0028] For example, f ＩＦ is f ＮＭＲ is a frequency sufficiently higher than f ＲＦ is f ＩＦ For example, f ＮＭＲ = 1 kHz, f ＲＦ = 43 MHz, f ＩＦ = 30 kHz (or f ＩＦ = 100 kHz).

[0029] Fig. 2 is a block diagram showing the configuration of the digitizing device 21 in Fig. 1. The digitizing device shown in Fig. 1 includes a physical field generating device 41, an optical quantum sensor unit 42, and an analog-to-digital converter (A / D converter, ADC) 43.

[0030] The physical field generator 41 generates a magnetic field corresponding to an input signal (i.e., an analog IF demodulated signal that has passed through the low-pass filter 7) input via an input terminal 41 a of the physical field generator 41. For example, the physical field generator 41 generates the magnetic field using a conductive coil or wiring.

[0031] The optical quantum sensor unit 42 comprises a sensor body 51 and a photoelectric element 52. In the sensor body 51, a sensing member generates light (observation light) corresponding to the magnetic field generated by the physical field generating device 41, and the light is converted into an electrical signal as a sensor signal by the photoelectric element 52. The photoelectric element 52 is a photodiode, phototransistor, or the like, and generates a sensor signal corresponding to the intensity of the incident observation light.

[0032] Specifically, the optical quantum sensor unit 42 (specifically, the sensor main body 51) performs quantum operations (here, quantum operations using microwaves and laser light) on the sensing element at a specific phase timing specified by the synchronization signal, causing the sensing element to generate light corresponding to the magnetic field generated by the physical field generating device 41.

[0033] In the first embodiment, the optical quantum sensor unit 42 (specifically, the sensor body 51) performs quantum operations on the sensing element in accordance with optically detected magnetic resonance (ODMR) to cause the sensing element to generate the above-mentioned observation light.

[0034] It is preferable that the phase detection unit 9 detects a specific phase in the waveform of the pseudo IF signal immediately after the start of free induction decay, and the optical quantum sensor unit 42 applies a microwave to the sensing member 1 at the timing of that specific phase, thereby performing the above-mentioned quantum operation on the sensing member 1.

[0035] Fig. 3 is a diagram showing the configuration of a sensor main body 51 in a digitizing device according to embodiment 1. In embodiment 1, for ODMR, as shown in Fig. 3, for example, the sensor main body 51 includes a magnetic resonance member 61 as a sensing member, a high-frequency magnetic field generator 62, a magnet 63, a high-frequency power supply 64, a light-emitting device 65, and a controller 66.

[0036] The magnetic resonance member 61 has a crystalline structure, and the electron spin quantum state changes in response to the magnetic field generated by the physical field generator 41. The magnetic resonance member 61 is a member capable of electron spin quantum manipulation (based on Rabi oscillation) using microwaves with a frequency corresponding to the alignment direction of defects and impurities in the crystal lattice. In other words, the magnetic resonance member 61 is placed in the above-mentioned magnetic field.

[0037] In this embodiment, the magnetic resonance element 61 is a photodetecting magnetic resonance element having a plurality (i.e., an ensemble) of specific color centers, each of which has energy levels that can be Zeeman split and can assume a plurality of orientations with different energy level shift widths upon Zeeman splitting.

[0038] Here, the magnetic resonance member 61 is a member such as diamond that includes multiple NV (Nitrogen Vacancy) centers as a single type of specific color center. In the case of NV centers, the ground state is a triplet state of ms = 0, +1, -1, and the ms = +1 and ms = -1 levels are Zeeman split. When the NV centers transition from the excited state of the ms = +1 and ms = -1 levels to the ground state, a certain proportion of them emit fluorescence, while the remaining proportion of NV centers transition from the excited state (ms = +1 or ms = -1) to the ground state (ms = 0) without radiation. Note that the color centers included in the magnetic resonance member 61 may be color centers other than NV centers.

[0039] The radio-frequency magnetic field generator 62 applies microwaves to the magnetic resonance member 61 to perform electron spin quantum manipulation of the magnetic resonance member 61. For example, the radio-frequency magnetic field generator 62 is a plate-shaped coil and includes a substantially circular coil portion that emits microwaves and terminal portions that extend from both ends of the coil portion and are fixed to a substrate. The radio-frequency power supply 64 generates a microwave current and conducts it to the radio-frequency magnetic field generator 62. The coil portion conducts two parallel currents at both end surfaces at a predetermined interval so as to sandwich the magnetic resonance member 61, thereby emitting the microwaves described above. In this example, although the coil portion is a plate-shaped coil, due to the skin effect, the microwave current flows through the end surfaces of the coil portion, forming two currents. As a result, microwaves of substantially uniform intensity are applied to the magnetic resonance member 61.

[0040] In the case of NV centers, color centers are formed in diamond crystals by defects (vacancies) (V) and nitrogen (N) as impurities, and there are four possible positions of adjacent nitrogen (N) relative to the defects (vacancies) (V) in the diamond crystal (i.e., the arrangement direction of the vacancy-nitrogen pair), and the sublevels (i.e., the energy levels from the ground level) after Zeeman splitting corresponding to each of these arrangement directions are different from each other. Therefore, in the characteristics of the fluorescence intensity after Zeeman splitting by the static magnetic field with respect to the microwave frequency, four different dip frequency pairs (fi+, fi-) appear corresponding to each direction i (i = 1, 2, 3, 4). Here, the frequency (wavelength) of the microwave described above is set corresponding to one of the dip frequencies of these four dip frequency pairs.

[0041] The magnet 63 applies a static magnetic field (a direct current magnetic field) to the magnetic resonance member 61, and Zeeman-splits the energy levels of a plurality of specific color centers (here, a plurality of NV centers) in the magnetic resonance member 61. Here, the magnet 63 is a ring-shaped permanent magnet, such as a ferrite magnet, an alnico magnet, or a samarium-cobalt magnet. The magnet 63 may also be an electromagnet.

[0042] Furthermore, in the magnetic resonance member 61, the crystals of the magnetic resonance member 61 are formed and the orientation of the magnetic resonance member 61 is set so that the arrangement direction of the above-mentioned defects and impurities approximately coincides with the direction of the above-mentioned static magnetic field (and the direction of the applied magnetic field).

[0043] Furthermore, in this embodiment, an optical system (not shown) is provided from the light-emitting device 65 to the magnetic resonance member 61 in order to irradiate the magnetic resonance member 41 with excitation light, and an optical system (not shown) is provided from the magnetic resonance member 61 to the photoelectric element 52 in order to detect fluorescence (observation light) from the magnetic resonance member 61.

[0044] The observation light is collected by an optical system such as a compound parabolic concentrator (CPC) toward the photoelectric element 52. For example, a magnetic resonance member 61 is disposed on the CPC, and among the fluorescence emitted in all directions from the color center in the magnetic resonance member 61, the fluorescence that is emitted in a wide solid angle (for example, a predetermined percentage or more in all directions) is collected by this optical system.

[0045] The light emitting device 65 includes a laser diode or the like as a light source, and emits laser light of a predetermined wavelength as excitation light to be irradiated onto the magnetic resonance member 61 from the light source.

[0046] The controller 66 (a) controls the high-frequency power supply 64 and the light-emitting device 65 in accordance with a predetermined measurement sequence (e.g., a Hahn echo sequence) to perform quantum operations with the microwaves and laser light described above, thereby causing the sensor main body 51 to generate observation light and the photoelectric element 52 to generate a sensor signal. For example, the controller 66 includes a computer that operates according to a control program, and the computer includes a CPU, ROM, RAM (Random Access Memory), etc., and performs the above-mentioned operations by loading the control program into the RAM and executing it on the CPU. Note that the controller 66 may be built into the control device 22, or the control device 22 may operate as the controller 66.

[0047] 4 is a diagram illustrating a specific phase in a pseudo-IF signal. In this embodiment, as shown in FIG. 4, for example, phase detection unit 9 detects consecutive specific phases of 0 degrees, 180 degrees, and 360 degrees in the waveform of the pseudo-IF signal, and optical quantum sensor unit 42 performs the above-mentioned quantum operation on sensing member 1 by applying microwaves to sensing member 1 at timings T1, T2, and T3 of the detected specific phases in accordance with the Hahn echo sequence. In accordance with the Hahn echo sequence, a π / 2 pulse of microwaves is applied at timings T1 and T3, and a π pulse of microwaves is applied at timing T2.

[0048] The frequency f of the pseudo IF signal ＩＦ and the frequency of the IF demodulated signal (f ＩＦ +f ＮＭＲ) and the difference (=f ＮＭＲ ) but f ＮＭＲ ga f ＩＦ 4, the pseudo-IF signal is nearly synchronized with the IF demodulation signal (especially at the beginning of observation). Therefore, the above-mentioned quantum operation is performed at an appropriate timing in the IF demodulation signal based on the above-mentioned synchronization signal.

[0049] The measurement sequence is not limited to the Hahn echo sequence, and may be selected according to the frequency of the magnetic field to be measured. For example, when the period of the magnetic field is equal to or longer than the T2 relaxation time, the magnetic field measurement may be performed using a Ramsey pulse sequence multiple times as described above. When the period of the magnetic field is shorter than the T2 relaxation time, a spin echo pulse sequence (such as a Hahn echo sequence) may be applied. When the period of the magnetic field is shorter than half the T2 relaxation time, the magnetic field measurement may be performed according to the Qdyne method.

[0050] Returning to FIG. 2, the A / D converter 43 digitizes the above-mentioned sensor signal (without digitizing the input signal), thereby generating a digital signal as an output signal corresponding to the input signal (IF demodulated signal), and outputs it via the output terminal 43 a of the A / D converter 43.

[0051] In this embodiment, in particular, the optical quantum sensor unit 42 (specifically, the sensor body 51) generates the above-mentioned observation light in the sensing member (magnetic resonance member 61) so that the level of the sensor signal exceeds the noise floor of the A / D converter 43.

[0052] Here, the level (amplitude) of the sensor signal varies depending on factors such as the efficiency of the sensing member (in the first embodiment, the type and number of color centers in the magnetic resonance member 61, etc.), the light-gathering efficiency of the observation light (in the first embodiment, the amount of light incident on the photoelectric element 52 relative to the amount of light emitted by the color center), and the conversion efficiency of the photoelectric element 52 (the level of the sensor signal relative to the amount of incident light). Therefore, the values ​​of these factors are determined depending on the noise floor (known) of the A / D converter 43 so that the level of the sensor signal exceeds the noise floor of the A / D converter 43. As a result, for example, the sensitivity of the optical quantum sensor unit 42 can be set to 1.5 pT / Hz. 1 / 2 That is all.

[0053] Generally, noise from an A / D converter includes quantization noise and thermal noise, and in a high-resolution A / D converter, thermal noise is dominant compared to quantization noise. The A / D converter 43 in this embodiment is a high-resolution A / D converter, and the values ​​of the above factors are determined so that the level of the sensor signal exceeds the noise level of thermal noise.

[0054] The reference voltage of the A / D converter 43 is set according to the range (minimum and maximum levels) of the sensor signal. Note that lowering the reference voltage of the A / D converter reduces quantization noise, but does not reduce thermal noise.

[0055] The level (or range) of the input IF demodulated signal and the electromagnetic conversion efficiency of the physical field generator 41 are known.

[0056] In particular, in this embodiment, the digitizing device 21 does not include an amplifier circuit between the photoelectric element 52 and the A / D converter 43 that electrically amplifies the sensor signal. Furthermore, in this embodiment, no amplifier circuit that electrically amplifies the input signal is provided between the signal source of the input signal and the physical field generating device 41. In other words, in this embodiment, no electrical amplifier circuit that could be a noise source is provided upstream of the A / D converter 43. In such an amplifier circuit, thermal noise is generated and amplified, just like in the A / D converter 43, and therefore noise is superimposed on the signal input to the A / D converter 43. Therefore, it is preferable not to provide such an amplifier circuit.

[0057] The high frequency power supply 64 and the controller 66 are electrically separated from the A / D converter 43 so that electrical noise generated in the high frequency power supply 64 and the controller 66 does not enter the A / D converter 43 .

[0058] Furthermore, in this embodiment 1, the optical quantum sensor unit 42 (controller 66) periodically and repeatedly performs quantum operations on the sensing element in accordance with the synchronization signal, causing the sensing element to generate light corresponding to the magnetic field, thereby causing the digitizing device 21 to output a digital IF demodulated signal in synchronization with the synchronization signal. Then, based on this digital IF demodulated signal, the control device 22 accurately calculates the frequency f of the NMR signal in accordance with the Qdyne method. ＮＭＲ Identify.

[0059] In this first embodiment, neither an amplifier circuit nor a buffer is provided between the nuclear magnetic resonance sensing unit 1 and the digitizing device 21. In other words, only passive elements are used in the circuit from the nuclear magnetic resonance sensing unit 1 to the digitizing device 21, and the generation of thermal noise is suppressed.

[0060] Next, the operation of the nuclear magnetic resonance sensing device according to the first embodiment will be described.

[0061] The control device 22 controls the nuclear magnetic resonance sensing unit 1 and also controls the switching unit 4 to apply a high-frequency magnetic field based on an RF signal from the transmission system to the target object 101 in the nuclear magnetic resonance sensing unit 1, and controls the switching unit 4 to conduct the observation signal from the nuclear magnetic resonance sensing unit 1 to the receiving system.

[0062] As shown in FIG. 1, the observation signal is converted into an IF demodulated signal based on the LO signal by the mixer unit 6, and the IF demodulated signal from which the high frequency band components have been removed by the low pass filter 7 is input to the digitizing device 21.

[0063] Furthermore, the mixer unit 8 generates a pseudo IF signal from the RF signal and the LO signal, and the phase detector unit 9 generates a synchronization signal indicating a specific phase from the pseudo IF signal.

[0064] In the digitizing device 21, when the IF demodulated signal is applied to the physical field generating device 41, a magnetic field of a strength corresponding to the level of the input signal is generated in the physical field generating device 41 and applied to the sensor body 51 of the optical quantum sensor unit 42.

[0065] In the sensor main body 51, the measurement sequence is executed in synchronization with the synchronization signal as described above, and light of an amount corresponding to the strength of the magnetic field is generated. In the first embodiment, in accordance with ODMR, the magnetic resonance element 61 generates light of an amount corresponding to the strength of the magnetic field.

[0066] The photoelectric element 52 receives the light, generates a sensor signal at a level corresponding to the amount of received light, and outputs the signal to the A / D converter 43 .

[0067] The A / D converter 43 digitizes the sensor signal to generate a digital IF demodulated signal corresponding to the analog IF demodulated signal, and outputs the digital IF demodulated signal to the control device 22 .

[0068] The control device 22 continuously and repeatedly acquires the value of the digital IF demodulated signal, and as described above, processes the signal to generate an NMR signal (specifically, f ＮＭＲ Based on the NMR signals, molecular structure analysis, imaging, etc. of the target object 101 are performed.

[0069] As described above, according to the first embodiment, the nuclear magnetic resonance sensing unit 1 applies a high-frequency magnetic field based on an RF signal to a target object and generates an observation signal having a frequency shifted from the frequency of the RF signal by the frequency of the NMR signal. The mixer unit 6 generates an IF demodulated signal including the NMR signal based on the LO signal. The low-pass filter 7 attenuates the high-frequency band components of the IF demodulated signal. Meanwhile, the mixer unit 8 generates a pseudo-IF signal from the LO signal and the RF signal, and the phase detector 9 detects a specific phase in the waveform of the pseudo-IF signal. In the digitizing device 21, the physical field generator 41 generates a magnetic field or the like corresponding to the IF demodulated signal that has passed through the low-pass filter 7, the optical quantum sensor unit 42 generates light corresponding to the magnetic field or the like using a sensing element, converts the light into a sensor signal using a photoelectric element, and the analog-to-digital converter 43 digitizes the sensor signal. The optical quantum sensor unit 42 performs quantum operations on the sensing member at the timing of the detected specific phase, causing the sensing member to generate light corresponding to the magnetic field or electric field described above.

[0070] As a result, quantum operations are performed in synchronization with the pseudo IF signal, which is nearly synchronized with the IF demodulation signal, so that the timing for performing the quantum operations is set appropriately and nuclear magnetic resonance sensing is performed with good sensitivity.

[0071] Embodiment 2.

[0072] 5 is a block diagram showing the configuration of a nuclear magnetic resonance sensing device according to embodiment 2 of the present invention. As shown in FIG. 5, the nuclear magnetic resonance sensing device according to embodiment 2 further includes a switching unit 81 and a 90-degree phase shifter 82.

[0073] The 90-degree phase shifter 82 shifts the phase of the LO signal by 90 degrees at the intermediate frequency fIF. The switching unit 81 is controlled by the control device 22 and switches between inputting the LO signal to the 90-degree phase shifter 82 and outputting the LO signal after the 90-degree phase shift to the mixer units 6 and 8, or bypassing the 90-degree phase shifter 82 and outputting the LO signal (the LO signal that has not been phase-shifted by 90 degrees) to the mixer units 6 and 8. For example, the control device 22 causes the switching unit 81 to alternately output the LO signal and the LO signal after the 90-degree phase shift for each of the above-mentioned measurement sequences in the digitizing device 21.

[0074] Therefore, the mixer unit 6 (a) generates an IF demodulated signal based on the LO signal, and (b) generates an IF demodulated signal based on the LO oscillation signal after a 90-degree phase shift. The mixer unit 8 (a) generates a pseudo-IF signal from the LO signal and the RF signal, and (b) generates a pseudo-IF signal after a 90-degree phase shift from the LO signal and the RF signal after a 90-degree phase shift.

[0075] The digitizing device 21 (a) digitizes the IF demodulated signal and outputs it to the control device 22, and (b) digitizes the IF demodulated signal after a 90-degree phase shift and outputs it to the control device 22. In the control device 22, a demodulated signal I for quadrature phase detection is generated based on the digitized IF demodulated signal, and a demodulated signal Q for quadrature phase detection is generated based on the digitized IF demodulated signal after a 90-degree phase shift.

[0076] In the second embodiment, the control device 22 demodulates the digitized IF demodulated signal and the digitized IF demodulated signal after a 90-degree phase shift to generate a demodulated signal I and a demodulated signal Q (frequency component f ＮＭＲ ) are generated and subjected to predetermined signal processing to generate an NMR signal (frequency component f ＮＭＲ In this predetermined signal processing, a Fourier transform such as an FFT (Fast Fourier Transform) is performed on each of the demodulated signal I and the demodulated signal Q to identify the frequency components of each of the demodulated signal I and the demodulated signal Q, thereby extracting an NMR signal (frequency component f ＮＭＲ ) and detect chemical shifts.

[0077] The other configurations and operations of the nuclear magnetic resonance sensing device according to the second embodiment are the same as those of the first embodiment, and therefore, description thereof will be omitted.

[0078] Embodiment 3.

[0079] 6 is a block diagram showing the configuration of a nuclear magnetic resonance sensing device according to a third embodiment of the present invention. As shown in FIG. 6, the nuclear magnetic resonance sensing device according to the third embodiment includes mixer units 6A and 6B similar to mixer unit 6, low-pass filters 7A and 7B similar to low-pass filter 7, mixer units 8A and 8B similar to mixer unit 8, and phase detectors 9A and 9B similar to phase detector 9. Furthermore, a digitizing device 21 according to the third embodiment includes digitizing units 21A and 21B similar to the digitizing device 21 according to the first or second embodiment. That is, in the third embodiment, two measurement systems are provided to obtain a demodulated signal I and a demodulated signal Q by quadrature phase detection, respectively.

[0080] 6, the third embodiment is provided with branching units 2a, 2aa, 3a, 3aa, 3ab, and 4a, such as couplers or splitters, and the RF signals branched by the branching units 2a and 2aa are input to mixer units 8A and 8B, respectively. The LO signal branched by the branching unit 3a is input to a 90-degree phase shifter 82, the LO signal branched by the branching unit 3aa is input to the mixer unit 8A, and the LO signal branched by the branching unit 3ab and shifted by 90 degrees is input to the mixer unit 8B. The observation signal branched by the branching unit 4a is input to the mixer units 6A and 6B.

[0081] The phase detectors 9A and 9B detect specific phases in the waveforms of the pseudo IF signals from the mixer units 8A and 8B, respectively, and generate and output synchronization signals indicating the specific phases.

[0082] On the other hand, the mixer unit 6A performs intermediate frequency demodulation of the observation signal based on the LO signal to generate an intermediate frequency demodulated signal (IF demodulated signal) including the nuclear magnetic resonance signal, and the mixer unit 6B performs intermediate frequency demodulation of the observation signal based on the LO signal after a 90-degree phase shift to generate an intermediate frequency demodulated signal (IF demodulated signal) including the nuclear magnetic resonance signal.

[0083] The low-pass filters 7A and 7B filter two band components (2f ＲＦ -f ＩＦ -f ＮＭＲ ), (fIF+f ＮＭＲ ) of the high frequency band component (2f ＲＦ -f ＩＦ -f ＮＭＲ ) and attenuates the low-frequency component (f ＩＦ +f ＮＭＲ The IF demodulated signals that have passed through the low-pass filters 7A and 7B are input to digitizing units 21A and 21B, respectively.

[0084] Similar to the digitizing device 21 of the first embodiment, the digitizing unit 21A uses the synchronization signal from the phase detection unit 9A to convert the IF demodulated signal output from the low-pass filter 7A from an analog signal to a digital signal, and outputs this digital signal to the control device 22 as an IF demodulated signal for the demodulated signal I of the quadrature detection. Also, similar to the digitizing device 21 of the first embodiment, the digitizing unit 21B uses the synchronization signal from the phase detection unit 9B to convert the IF demodulated signal output from the low-pass filter 7B from an analog signal to a digital signal, and outputs this digital signal to the control device 22 as an IF demodulated signal for the demodulated signal Q of the quadrature detection.

[0085] In the third embodiment, the control device 22 demodulates the digitized IF demodulated signal obtained from the digitizing units 21A and 21B and the digitized IF demodulated signal after 90 degrees phase shift to generate a demodulated signal I and a demodulated signal Q (frequency component f ＮＭＲ ) are generated and subjected to predetermined signal processing to generate an NMR signal (frequency component f ＮＭＲ In this predetermined signal processing, a Fourier transform such as an FFT (Fast Fourier Transform) is performed on each of the demodulated signal I and the demodulated signal Q to identify the frequency components of each of the demodulated signal I and the demodulated signal Q, thereby extracting an NMR signal (frequency component f ＮＭＲ) and detects chemical shifts. In particular, in the third embodiment, the switching unit 81 shown in the second embodiment is not provided, and the demodulated signal I and the demodulated signal Q are simultaneously acquired, so that a wideband NMR signal can be extracted in a short time.

[0086] The other configurations and operations of the nuclear magnetic resonance sensing device according to the third embodiment are the same as those of the first or second embodiment, and therefore, description thereof will be omitted.

[0087] It should be noted that various changes and modifications to the above-described embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing its intended advantages. In other words, it is intended that such changes and modifications be included within the scope of the claims.

[0088] For example, in embodiments 1, 2, and 3, the measurement method in the sensor body 51 is not limited to the above-mentioned ODMR, and any other measurement method may be used as long as it is capable of using a sensing element corresponding to a physical field and performing quantum operations on the sensing element to detect observation light corresponding to the physical field intensity.

[0089] In addition, in embodiments 1, 2, and 3, the control device 22 may perform a predetermined arithmetic operation on the output signal of the digitizing device 21 so that the value (digital value) of the output signal matches the level of the analog IF demodulated signal.

[0090] In the first, second and third embodiments, a low-noise buffer (voltage amplification factor=1) that satisfies the noise level requirement may be provided between the low-pass filter 7 and the digitizing device 21 as needed.

[0091] Furthermore, the digitizing device 21 in the first and second embodiments and the digitizing units 21A and 21B in the third embodiment may be the same as those described in International Publication No. 2023 / 089883.

[0092] The present invention is applicable to, for example, various measurements and imaging that utilize nuclear magnetic resonance.

Claims

1. A nuclear magnetic resonance sensing apparatus, comprising: a nuclear magnetic resonance sensing unit that applies a high-frequency magnetic field based on an RF signal to a target object and generates an observation signal having a frequency shifted from the frequency of the RF signal by the frequency of a nuclear magnetic resonance signal; a first mixer unit that performs intermediate-frequency demodulation of the observation signal based on a local oscillation signal to generate an intermediate-frequency demodulated signal including the nuclear magnetic resonance signal; a low-pass filter that attenuates a high-frequency band-side component of the intermediate-frequency demodulated signal; a digitizing device that digitizes the intermediate-frequency demodulated signal transmitted through the low-pass filter; a second mixer unit that generates a pseudo intermediate-frequency signal from the local oscillation signal and the RF signal; and a phase detection unit that detects a specific phase in the waveform of the pseudo intermediate-frequency signal, wherein the digitizing device includes a physical field generating device that generates a magnetic field or an electric field corresponding to the intermediate-frequency demodulated signal transmitted through the low-pass filter, an optical quantum sensor unit that generates light corresponding to the magnetic field or the electric field with a sensing member and converts the light into an electrical signal as a sensor signal with a photoelectric element, and an analog / digital converter that digitizes the sensor signal, and the optical quantum sensor unit performs a quantum operation on the sensing member at the timing of the detected specific phase to generate the light corresponding to the magnetic field or the electric field on the sensing member.

2. The nuclear magnetic resonance sensing apparatus according to claim 1, wherein the optical quantum sensor unit performs the quantum operation on the sensing member at the timing of the detected specific phase according to the optically detected magnetic resonance measurement method to generate the light corresponding to the magnetic field or the electric field on the sensing member.

3. The nuclear magnetic resonance sensing apparatus according to claim 2, wherein the phase detection unit detects 0 degrees, 180 degrees, and 360 degrees as the specific phase in the waveform of the pseudo intermediate-frequency signal, and the optical quantum sensor unit performs a quantum operation on the sensing member by applying a microwave to the sensing member at the timing of the detected specific phase according to a Hahn echo sequence to generate the light corresponding to the magnetic field or the electric field on the sensing member.

4. The nuclear magnetic resonance sensing device according to claim 1, wherein the phase detection unit detects the specific phase immediately after the start of free induction decay in the waveform of the pseudo intermediate frequency signal.

5. The nuclear magnetic resonance sensing device according to claim 1, further comprising a 90-degree phase shifter that performs a 90-degree phase shift at an intermediate frequency with respect to the local oscillation signal, wherein the first mixer unit: (a) generates the intermediate frequency demodulation signal based on the local oscillation signal, and (b) generates the intermediate frequency demodulation signal based on the local oscillation signal after 90-degree phase shift; the second mixer unit: (a) generates the pseudo intermediate frequency signal from the local oscillation signal and the RF signal, and (b) generates the pseudo intermediate frequency signal after 90-degree phase shift from the local oscillation signal after 90-degree phase shift and the RF signal; and the digitizing device: (a) digitizes the intermediate frequency demodulation signal, and (b) digitizes the intermediate frequency demodulation signal after 90-degree phase shift.

6. A step of applying a high-frequency magnetic field based on an RF signal to a target object and generating an observation signal having a frequency shifted from the frequency of the RF signal by the frequency of a nuclear magnetic resonance signal; a step of performing intermediate-frequency demodulation of the observation signal based on a local oscillation signal to generate an intermediate-frequency demodulated signal including the nuclear magnetic resonance signal; a step of attenuating a high-frequency band-side component of the intermediate-frequency demodulated signal with a low-pass filter; a digitizing step of digitizing the intermediate-frequency demodulated signal that has passed through the low-pass filter with a digitizing device; a step of generating a pseudo intermediate-frequency signal from the local oscillation signal and the RF signal; a step of detecting a specific phase in the waveform of the pseudo intermediate-frequency signal, wherein in the digitizing step, (a) a magnetic field or an electric field corresponding to the intermediate-frequency demodulated signal that has passed through the low-pass filter is generated, (b) light corresponding to the magnetic field or the electric field is generated by a sensing member, (c) the light is converted into an electric signal as a sensor signal by a photoelectric element, (d) the sensor signal is digitized by an analog / digital converter, and in the digitizing step, a quantum operation is performed on the sensing member at the timing of the detected specific phase to generate the light corresponding to the magnetic field or the electric field in the sensing member. A nuclear magnetic resonance sensing method characterized by the above.

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