Quantum wide-field magnetic microscope

Abstract

Provided is a quantum wide-field magnetic microscope, comprising: a probe module comprising an objective lens and a sample stage, the sample stage being used to carry a sample to be measured and a diamond NV color center spin sensor overlaid on the sample to be measured; an excitation light path module configured to generate laser light and irradiate the laser light on the diamond NV color center spin sensor at a set angle, so that the NV color center generates fluorescence; a microwave module comprising a microwave source and a radiation structure, the radiation structure being non-contactingly arranged between the objective lens and the diamond NV color center spin sensor, the microwave source being used to emit microwave signals at a set timing and a set frequency, and the radiation structure being configured to generate a microwave magnetic field acting on the diamond NV color center spin sensor by the microwave signals; a fluorescence imaging module used to collect fluorescence after the microwave magnetic field acts on the diamond NV color center spin sensor and generate a fluorescence intensity distribution map; and a data processing module used to calculate a magnetic field image of the sample to be measured based on the fluorescence intensity distribution map.

Description

Technical Field

[0001] This disclosure relates to the field of magnetic imaging technology, and more particularly to a quantum wide-field magnetic microscope. Background Technology

[0002] Currently, the magnetic measurement and imaging of magnetic fields generated by magnetic particles in magnetic samples, rocks and minerals, and currents in integrated circuits and chips mainly includes the following three techniques. Technique one, as described in "Micrometer-scale magnetic imaging of geological samples using a quantum diamond microscope" [Geochem. Geophys. Geosyst., 18, 3254-3267 (2017)], is the first to apply a quantum wide-field magnetic microscope to geological samples, achieving imaging of stray magnetic fields generated by magnetic particles in rock samples. The experimental setup is shown below. This device uses a nitrogen-vacancy spin two-dimensional array in diamond as a sensor and a wide-field fluorescence microscope as a detector; the radiating structure remains in contact with the sample. In terms of experimentation, data acquisition and command synchronization are still software-synchronized, resulting in low efficiency. Technology two, as described in "HIGH-RESOLUTION MAGNETIC FIELD FINGERPRINTING OF INTEGRATEDCIRCUIT ACTIVITY WITH A QUANTUM DIAMOND MICROSCOPE" (patent US20210239779), applies quantum precision measurement technology based on diamond nitrogen-vacancy spin to integrated circuits, realizing magnetic imaging of integrated circuits. The device still uses free light, a radiation structure attached to the sample, and software-level command synchronization, resulting in low efficiency. Technology three, as described in "Coupled Magnetic Imaging Device and Measurement Method" (CN202111311579.X), mainly invents a magnetic coupling microscope device. Its optical path uses free light, a radiation structure attached to the sample, and software-level command synchronization, resulting in low efficiency.

[0003] However, the above methods have poor sensitivity, low efficiency and are difficult to operate. Therefore, there is an urgent need for a better quantum wide-field magnetic microscope. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the aforementioned issues, this disclosure provides a quantum wide-field magnetic microscope to alleviate the technical problems of poor sensitivity, low efficiency, and difficult operation in existing magnetic measurement and imaging technologies.

[0006] (II) Technical Solution

[0007] This disclosure provides a quantum wide-field magnetic microscope, including: a probe module, an excitation optical path module, a microwave module, a fluorescence imaging module, and a data processing module.

[0008] The probe module includes an objective lens and a sample stage, the sample stage being used to hold the sample to be tested and a diamond NV center spin sensor covering the sample to be tested; the excitation optical path module is configured to generate a laser and irradiate the diamond NV center spin sensor at a set angle, thereby causing the NV center to fluoresce; the microwave module includes a microwave source and a radiation structure, the radiation structure being non-contactly disposed between the objective lens and the diamond NV center spin sensor, the microwave source being used to emit microwave signals according to a set time sequence and a set frequency, and the radiation structure being configured to generate a microwave magnetic field from the microwave signals and act on the diamond NV center spin sensor; the fluorescence imaging module is used to collect the fluorescence after the microwave magnetic field acts on the diamond NV center spin sensor and generate a fluorescence intensity distribution map; the data processing module calculates the magnetic field image of the sample to be tested based on the fluorescence intensity distribution map.

[0009] According to an embodiment of this disclosure, one side opening of the radiating structure serves as a laser guiding hole for the laser to pass through. A through hole is provided at the end of the laser guiding hole, and a copper-clad wire is provided on the through hole. The copper-clad wire is used to generate a microwave magnetic field under the action of a microwave signal. The radiating structure is disposed between the objective lens and the diamond NV color center spin sensor by a fixed bracket, so that the radiating structure does not contact the diamond NV color center spin sensor and the objective lens.

[0010] According to an embodiment of this disclosure, the diamond NV color center spin sensor has a length of no more than 3 mm, a thickness of no more than 1 mm, and a beveled surface on one side, wherein the angle between the beveled surface and the horizontal direction is between 35 and 55 degrees.

[0011] According to an embodiment of this disclosure, the diamond NV center is located on the side of the diamond NV center spin sensor closer to the sample to be tested, and it converts the magnetic field signal of the sample to be tested into a fluorescence signal through quantum effect.

[0012] According to embodiments of this disclosure, the probe module further includes a Helmholtz coil for applying a uniform external magnetic field of adjustable magnitude and orientation to the sample to be tested.

[0013] According to an embodiment of this disclosure, the quantum wide-field magnetic microscope further includes a synchronization control module. The synchronization control module includes an arbitrary sequence generator with a sequence time control accuracy better than 1 μs and a number of output channels greater than or equal to 3. The generator sends control signals to control the output switches of the laser module, the microwave module, and the playback of the set frequency list of the microwave system.

[0014] According to embodiments of this disclosure, the frequencies in the frequency list are set between 2-4 GHz, the number of frequencies in the frequency list is set between 10-200, and the frequency interval is set between 10-1000 kHz.

[0015] According to an embodiment of this disclosure, the excitation optical path module includes a laser, a multimode homogenizing fiber, and an angle-adjustable beam focuser. The laser is coupled into the multimode homogenizing fiber through a coupling device, and then the beam focuser focuses the laser from the multimode homogenizing fiber onto the oblique surface of the diamond NV center spin sensor, thereby acting on the side with the diamond NV center to form a light spot with uniform power density.

[0016] According to embodiments of this disclosure, the fluorescence imaging module includes a CCD or sCMOS type scientific camera, and the completed exposure preparation of the scientific camera is connected to an external trigger interface of an arbitrary sequence generator.

[0017] According to embodiments of this disclosure, the external trigger interface of the arbitrary sequence generator is connected to the trigger output of the scientific camera and can receive trigger pulse signals to perform pulse output. The pulse output sequence is described as follows: a) After receiving the trigger pulse, the channels controlling the output switch of the laser module and the channel controlling the output switch of the microwave module are both at high level, while other channels are at low level. The duration t is the same as or less than the exposure time of each frame, used to collect fluorescence signals. This process is repeated n times, 1≤n≤1000; b) After receiving the trigger pulse again, the channel controlling the output switch of the laser module is at high level, while other channels are at low level. The duration is longer than t, used to collect fluorescence reference signals. This process is repeated n times; c) a and b are repeated m times, 1≤m≤1000; d) The channel controlling the output switch of the microwave module is at high level, used to trigger the microwave module to change its frequency; f) Step a and b are repeated l times, where l is an integer multiple of the number of frequencies in the frequency list.

[0018] (III) Beneficial Effects

[0019] As can be seen from the above technical solution, the quantum wide-field magnetic microscope disclosed herein has at least one or a portion of the following beneficial effects:

[0020] (1) When the radiation structure is working, it needs to be supplied with high-power microwaves, which will generate a lot of heat. The present invention discloses a structure that separates the radiation structure from the sample, which can avoid the direct transfer of this heat to the sample and the resulting temperature rise and drift.

[0021] (2) The Ω-shaped radiation structure can generate microwaves that are more uniform in the radiation space, avoiding the peak broadening effect caused by microwave non-uniformity.

[0022] (3) The separate structure of the radiation structure from the sample means that the radiation structure does not need to be removed when changing the sample, which reduces the time loss of reconnecting the circuit and improves the experimental efficiency of the measurement.

[0023] (4) The modularity level has been improved, with the excitation optical path based on homogenized optical fiber replacing the original free light excitation optical path. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the composition and structure of a quantum wide-field magnetic microscope according to an embodiment of the present disclosure, wherein the dashed box is a magnified view of a part.

[0025] Figure 2 This is a schematic diagram of the radiation structure according to an embodiment of the present disclosure.

[0026] Figure 3 This is a three-dimensional schematic diagram showing the relative positional relationship between the radiation structure, objective lens, and laser in an embodiment of this disclosure.

[0027] Figure 4 This is a side view schematic diagram showing the relative positional relationship between the radiation structure, objective lens, and laser in an embodiment of this disclosure.

[0028] Figure 5 This is a schematic diagram illustrating the working principle and connection relationship of the quantum wide-field magnetic microscope according to an embodiment of this disclosure.

[0029] Figure 6 This is a schematic diagram of a pulse sequence for an arbitrary sequence generator according to an embodiment of the present disclosure.

[0030] Figure 7 This is a schematic diagram of the test results of magnetic particle imaging performed by a quantum wide-field magnetic microscope according to an embodiment of this disclosure. Detailed Implementation

[0031] This disclosure provides a quantum wide-field magnetic microscope that addresses the challenge of magnetic imaging of micrometer-scale samples at room temperature and atmospheric conditions. It utilizes diamond nitrogen-vacancy spin quantum precision measurement technology to achieve magnetic measurement and imaging of the sample, offering advantages such as high sensitivity, high efficiency, radiation structure-sample separation, high modularity, and ease of operation. Measurement targets include magnetic samples, magnetic particles in rocks and minerals, and magnetic fields generated by currents in integrated circuits and chips.

[0032] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0033] The working principle of quantum wide-field magnetic microscopy is to use the spin of the NV center in diamond as a sensor. As an electron spin, the energy level splitting of the diamond NV center changes when it approaches a magnetic sample. By measuring the change in energy level splitting, the magnitude of the magnetic field experienced by the NV center can be deduced. Because the size of the NV center itself is only a few atoms, the magnetic field it receives can be considered as the magnetic field of the coordinates of the point where the NV center is located. The NV center can emit fluorescence. By measuring the change in fluorescence intensity under the action of external microwaves and lasers, the magnetic resonance spectrum of the NV center can be detected, which is called optically detected magnetic resonance. This disclosure uses a scientific camera to detect the fluorescence intensity of the NV center. This disclosure generates a thin layer of NV centers within a range of 10-100 nanometers below the diamond surface, and then uses an optical microscope system to map the NV centers to the pixels of the scientific camera in real space. In this way, the distribution image of the fluorescence intensity of the NV center in 2D space can be detected, and then the magnetic resonance spectrum of the NV center at different locations in space can be obtained through optically detected magnetic resonance experiments, thereby calculating the image of the magnetic field.

[0034] In this embodiment of the disclosure, a quantum wide-field magnetic microscope is provided, combined with Figures 1 to 5 As shown, the quantum wide-field magnetic microscope includes:

[0035] The probe module includes an objective lens 006 and a sample stage 005, wherein the sample stage 005 is used to support the sample to be tested 015 and the diamond NV color center spin sensor 014 covering the sample to be tested 015.

[0036] The excitation optical path module is configured to generate laser 10 and irradiate the diamond NV color center spin sensor 014 at a set angle, thereby causing the NV color center to fluoresce.

[0037] The microwave module includes a microwave source and a radiation structure 009. The radiation structure is non-contactly disposed between the objective lens 006 and the diamond NV color center spin sensor 014. The microwave source is used to emit microwave signals according to a set timing and a set frequency. The radiation structure is configured to generate a microwave magnetic field from the microwave signals and apply it to the diamond NV color center spin sensor 014.

[0038] A fluorescence imaging module is used to collect fluorescence after a microwave magnetic field is applied to a diamond NV color center spin sensor and generate a fluorescence intensity distribution map.

[0039] The data processing module calculates the magnetic field image of the sample under test based on the fluorescence intensity distribution map.

[0040] According to embodiments of this disclosure, in conjunction with Figure 2 , Figure 3 and Figure 4As shown, one side opening of the radiation structure 009 serves as a laser guide hole 019 for laser transmission. A through hole is located at the end of the laser guide hole 019, and a copper-clad conductor is installed on the through hole, forming a copper-clad Ω-shaped conductor 016. This copper-clad conductor generates a microwave magnetic field under the influence of a microwave signal. The opening is perpendicular to the microstrip line of the radiation structure 009, allowing the laser to pass through along the opening. The radiation structure is positioned between the objective lens 006 and the diamond NV color center spin sensor 014 via a fixing bracket 008, ensuring that the radiation structure does not contact the diamond NV color center spin sensor 014 or the objective lens 006. The radiation structure 009 is connected to a coaxial cable 017 via an SMA-type microwave cable connector 018. The radiation structure 009 is fixed in position by fixing screws 20.

[0041] According to embodiments of this disclosure, the diamond NV color center spin sensor 014 has a length not exceeding 3 mm, a thickness not exceeding 1 mm, and a beveled surface on one side, such as... Figure 4 As shown, the angle between the oblique cut surface and the horizontal direction is between 35 and 55 degrees.

[0042] According to an embodiment of this disclosure, a diamond NV center is located on the side of the diamond NV center spin sensor 014 near the sample 015 to be tested, which converts the magnetic field signal of the sample to be tested into a fluorescence signal through quantum effects. The diamond NV center spin sensor 014 is placed on the sample 015 to be tested, and the sample 015 is located on the sample base 007 of the sample stage 005.

[0043] According to embodiments of this disclosure, such as Figure 1 As shown, the probe module also includes a Helmholtz coil 003, which is used to apply a uniform external magnetic field of adjustable magnitude and direction to the sample 015 to be tested.

[0044] According to embodiments of this disclosure, in conjunction with Figure 1 and Figure 5 As shown, the excitation optical path module includes a laser ( Figure 5 The system includes a laser system, a multimode homogenizing fiber and a multimode homogenizing fiber jumper 011, and an angle-adjustable beam focuser 012. The laser is coupled into the multimode homogenizing fiber through a coupling device, and then focused by the beam focuser onto the oblique surface of the diamond NV color center spin sensor 014, thereby acting on the side with the diamond NV color center to form a light spot with uniform power density. The angle-adjustable frame 013 is used to adjust the exit angle of the laser beam.

[0045] According to embodiments of this disclosure, the quantum wide-field magnetic microscope further includes a synchronization control module, which includes an arbitrary sequence generator with sequence timing control accuracy better than 1 μs and an output channel number greater than or equal to 3 (e.g., ...). Figure 3The diagram shows three pulse output channels (1, 2, and 3), which respectively send control signals to control the output switches of the laser module and microwave module, as well as the playback of the microwave system's preset frequency list. Pulse output channel 1 is connected to the laser module, pulse output channel 3 is connected to the microwave source in the microwave module, and pulse output channel 2 is connected to the microwave switch in the microwave module. The microwave module can receive two pulse trigger signals. When the trigger signal output by pulse output channel 2 is high, the microwave switch conducts and outputs a microwave signal. When the trigger signal output by pulse output channel 3 is high, the microwave source can play and output according to the preset frequency list, for example, changing the frequency up or down once.

[0046] According to embodiments of this disclosure, the frequencies in the set frequency list are between 2-4 GHz, the number of frequencies in the set frequency list is between 10-200, and the frequency interval is between 10-1000 kHz.

[0047] According to embodiments of this disclosure, in conjunction with Figure 1 and Figure 5 As shown, the fluorescence imaging module includes a CMOS or sCMOS type scientific camera 001. The scientific camera 001 is connected to the external trigger interface of an arbitrary sequence generator after completing exposure preparation. The scientific camera 001 is connected to a computer via a USB data cable or a Camera Link camera-specific connection cable. The trigger output of the scientific camera 001 is connected to the trigger input terminal of the arbitrary sequence generator. The scientific camera 001 can be set to continuous exposure mode, outputting a synchronization pulse when exposure preparation is complete and exposure begins.

[0048] According to an embodiment of this disclosure, the synchronization control module writes the pulse sequence into the buffer of the arbitrary sequence generator; the external trigger interface of the arbitrary sequence generator is connected to the trigger output of the scientific camera and can receive trigger pulse signals. During the experiment, the frequency list of the microwave signal generation system is set, and the initial frequency of the microwave signal generation system is the first frequency in the frequency list; the exposure frame number of the camera is set, the exposure mode is continuous exposure, and the exposure start pulse output function is turned on; the camera exposure begins; the arbitrary sequence generator receives the exposure start pulse output by the camera and begins to play the preset pulse sequence; after the camera completes one frame of exposure, the data is output to the computer's memory; the next frame of exposure is performed until all the preset number of frames are completed, and the experiment ends; the computer begins data processing and outputs the final image.

[0049] According to embodiments of this disclosure, in conjunction with Figure 6 As shown, the pulse output sequence of an arbitrary sequence generator can be expressed as follows:

[0050] a. After receiving the trigger pulse, the channels controlling the output switch of the laser module and the channel controlling the output switch of the microwave module are both at high level, while other channels are at low level. The time length t is the same as or less than the exposure time of each frame, and is used to collect fluorescence signals. This process is repeated n times, where 1≤n≤1000.

[0051] b. After receiving the trigger pulse again, the channel controlling the output switch of the laser module is at a high level, and the other channels are at a low level for a time longer than t, which is used to collect the fluorescence reference signal. This process is repeated n times.

[0052] c. Repeat a and b m times, where 1 ≤ m ≤ 1000;

[0053] d. The channel controlling the output switch of the microwave module is at a high level to trigger the microwave module to change its frequency;

[0054] f. Step ad is repeated l times, where l is an integer multiple of the number of frequencies in the frequency list.

[0055] According to embodiments of this disclosure, the main functions of the probe module include supporting the diamond NV center spin sensor 014 and the sample, irradiating the sample with laser or microwave, and collecting the fluorescence emitted by the diamond NV centers to form a fluorescence image. Structurally, the probe module may include the diamond NV center spin sensor 014, which contains a near-surface layer of diamond NV centers that can convert magnetic field signals into fluorescence intensity signals through quantum effects. The NV center layer is located 10-100 nanometers below the surface of the diamond NV center spin sensor 014, with a layer thickness of 5-10 nanometers, and an average spacing of 10-100 nanometers between the NV centers. A non-magnetic three-dimensional displacement platform and a two-dimensional pendulum sample stage 005 are used to support the diamond NV center spin sensor 014 and the sample 015 to be tested. The movement accuracy of the displacement platform is 1-10 micrometers, and the angular accuracy of the pendulum stage is less than 0.1 degrees.

[0056] According to embodiments of this disclosure, the microwave radiation structure 009 of the microwave module is used to radiate a microwave field to the diamond NV center spin sensor 014; the fluorescence imaging system may include a lens sleeve 002 and a scientific camera 001 based on a charge-coupled device (CCD) or a research-grade complementary metal-oxide-semiconductor (sCMOS) for collecting fluorescence from the NV centers and performing fluorescence imaging. The excitation optical path module may include a high-power 532 nm wavelength continuous wave or pulsed laser, a multimode homogenizing fiber, and an adjustable beam focuser. The laser is coupled into the multimode fiber through a coupling device. One end of the fiber is coupled into a coherent beam by a coherent light source, and the other end is focused from the inclined surface of the side of the diamond NV center spin sensor 014 through an optical fiber beam adjustment system onto the surface with nitrogen-vacancy site defects, forming a light spot with uniform power density; if the laser is a pulsed laser, then the pulse output of the laser needs to be controllable by an electrical pulse (TTL logic level) signal, with the laser on when the level is high and off when the level is low. The microwave module may include a microwave signal generator, a microwave switch, and a microwave amplifier. All components must cover a microwave frequency range of 2-4 GHz. The microwave signal generator must have a frequency list playback function; upon receiving a TTL rising edge, it should output a microwave frequency that changes to the next frequency according to the frequency list. The microwave switch must allow microwaves to pass through when it receives a TTL high-level signal and block them when it receives a TTL low-level signal. The switching ratio must be above 60 dB, and the rising edge time must be less than 100 nanoseconds.

[0057] According to embodiments of this disclosure, the synchronization control module may include a computer and an arbitrary sequence generator, wherein the computer needs to have large storage space and strong computing power. The arbitrary sequence generator has a buffer and can accept pulse trigger signals. Before the experiment, it can write the pulse sequence into the buffer, and after receiving the trigger signal, it can play the pulse sequence in the buffer. The computer is configured to play a predetermined pulse sequence and perform data acquisition and analysis.

[0058] According to the embodiments of this disclosure, the scientific research camera 001 is connected to a computer via a USB data cable or a Camera Link camera-specific connection cable. The trigger output of the scientific research camera 001 is connected to the trigger input terminal of an arbitrary sequence generator. One pulse output channel of the arbitrary sequence generator is connected to a microwave switch. One pulse output channel of the arbitrary sequence generator is connected to the pulse input of a laser. One pulse count channel of the arbitrary sequence generator is connected to the trigger input channel of a microwave signal generator.

[0059] According to an embodiment of this disclosure, the working process of the quantum wide-field magnetic microscope is as follows:

[0060] (1) With the side of the diamond NV center spin sensor 014 with the NV center facing the sample, place it on the region of interest on the sample, ensuring that the central region of the diamond NV center spin sensor 014 coincides with the region of interest.

[0061] (2) Place the sample together with the diamond NV color center spin sensor 014 on the sample stage 005 of the probe module, align one side of the inclined surface of the diamond NV color center spin sensor 014 with the laser incident direction, so that it is perpendicular to the projection of the laser beam 010 on the horizontal plane.

[0062] (3) Turn on the white light illumination source 004, adjust the position of the sample and the diamond NV center spin sensor 014 so that the plane of the NV center of the diamond NV center spin sensor 014 is aligned with the focal plane of the objective lens, and at the same time adjust the region of interest to the center of the field of view.

[0063] (4) Adjust the angle of the laser so that the excitation laser can cover the region of interest;

[0064] (5) Set the experimental parameters for magnetic imaging, including the pulse sequence of the arbitrary sequence generator, the frequency list of the microwave signal generator, the single-frame exposure time of the scientific camera 001, and the number of cycles for the entire experiment.

[0065] (6) Perform exposure and data acquisition. When the acquisition is complete, write the data to the hard disk.

[0066] (7) Data processing: The obtained data is integrated, and then the resonance peak of the NV color center at each pixel position is obtained by fitting the Lorentz curve using the least squares method. The magnetic field size is calculated. The magnetic field size at each pixel is plotted to form a magnetic field image.

[0067] According to an embodiment of this disclosure, a demonstration of the device's operation was conducted using magnetic particles with a diameter of 150 nanometers, and the measurement results are as follows: Figure 7 As shown. Figure 7 The externally applied 25 Gauss magnetic field has been subtracted, leaving only the changes in the spatial magnetic field caused by the magnetic particles. The image clearly shows the magnetic dipole moments of the magnetic particles, appearing as pairs of small positive and negative regions.

[0068] The embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. It should be noted that implementations not illustrated or described in the drawings or the main text of the specification are forms known to those skilled in the art and are not described in detail. Furthermore, the definitions of the various elements and methods described above are not limited to the specific structures, shapes, or methods mentioned in the embodiments, and those skilled in the art can easily modify or substitute them.

[0069] Based on the above description, those skilled in the art should have a clear understanding of the quantum wide-field magnetic microscope disclosed herein.

[0070] In summary, this disclosure provides a quantum wide-field magnetic microscope, which has significant advantages and positive effects compared to existing magnetic microscopes. For example: 1) The structure of the radiation structure 009 has the following advantages: (1) In the experiment, the radiation structure 009 will emit a large amount of heat. The structure of the radiation structure 009 separated from the sample in this disclosure can avoid the direct transfer of this heat to the sample, causing drift due to temperature rise; (2) The Ω-shaped radiation structure 009 can radiate microwaves that are more uniform in space, avoiding the peak broadening effect caused by microwave non-uniformity; (3) The structure of the radiation structure 009 separated from the sample in this disclosure means that when changing the sample, it is not necessary to remove the radiation structure 009, reducing the time loss of reconnecting the circuit. 2) The circuit connection and pulse sequence part has the following advantages: The background scheme does not mention the circuit connection and pulse sequence, or the software synchronization between the camera, microwave and control system. Software synchronization inevitably involves instruction processing time. For an image exposure time of 100 milliseconds, the instruction processing time is often also 100 milliseconds, meaning about half the time is wasted on instruction processing, resulting in an experimental time utilization efficiency of less than 50%. In contrast, this disclosure uses hardware synchronization, reducing instruction processing time to less than 1 millisecond and improving experimental efficiency to over 90%. 3) The construction of the excitation optical path has the following advantages: using a homogenizing fiber to guide the laser from the laser to the sample makes the excitation light intensity more uniform in space, eliminating edge effects in the resulting image; furthermore, it improves the modularity and maintenance convenience of the entire system, allowing for easy replacement of the laser without needing to adjust the optical path.

[0071] It should also be noted that the above are different embodiments provided by this disclosure. These embodiments are used to illustrate the technical content of this disclosure and are not intended to limit the scope of protection of this disclosure. A feature of one embodiment can be applied to other embodiments through suitable modifications, substitutions, combinations, or separations.

[0072] It should be noted that, unless otherwise specified herein, having "a" element is not limited to having a single element, but may include one or more of the element.

[0073] Furthermore, unless otherwise specified, the ordinal numbers such as "first," "second," etc., used herein are merely for distinguishing multiple elements with the same name and do not indicate any hierarchy, order of execution, or process sequence among them. A "first" element and a "second" element may appear together in the same component or separately in different components. The presence of an element with a higher ordinal number does not necessarily indicate the presence of another element with a lower ordinal number.

[0074] In this document, unless otherwise specified, the term "characteristic A" or "and / or" and "characteristic B" means that A exists alone, B exists alone, or A and B exist simultaneously; the term "characteristic A" and "and" or "and" and "and" and "characteristic B" means that A and B exist simultaneously; the terms "including", "containing", "having", and "containing" refer to, but are not limited to, these.

[0075] Furthermore, in this document, terms such as "up," "down," "left," "right," "front," "back," or "between" are used only to describe the relative positions of multiple elements and can be extended to include translation, rotation, or mirroring. Additionally, unless otherwise specified, the statement "one element is on another element" or similar statements do not necessarily indicate that the element is in contact with the other element.

[0076] Furthermore, unless specifically described or required to occur in a specific order, the order of the above steps is not limited to those listed above and can be varied or rearranged according to the desired design. Moreover, the above embodiments can be used in combination with each other or with other embodiments based on design and reliability considerations; that is, technical features from different embodiments can be freely combined to form more embodiments.

[0077] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A quantum wide-field magnetic microscope, comprising: The probe module includes an objective lens and a sample stage, the sample stage being used to hold the sample to be tested and a diamond NV color center spin sensor covered on the sample to be tested; The excitation optical path module is configured to generate laser light and irradiate the diamond NV color center spin sensor at a set angle, thereby causing the NV color center to fluoresce. A microwave module includes a microwave source and a radiation structure. The radiation structure is non-contactly disposed between the objective lens and the diamond NV color center spin sensor. The microwave source is used to emit microwave signals according to a set timing and a set frequency. The radiation structure is configured to generate a microwave magnetic field from the microwave signals and apply it to the diamond NV color center spin sensor. A fluorescence imaging module is used to collect fluorescence after a microwave magnetic field is applied to a diamond NV color center spin sensor and generate a fluorescence intensity distribution map. The data processing module calculates the magnetic field image of the sample under test based on the fluorescence intensity distribution map. The synchronization control module includes an arbitrary sequence generator with a sequence timing control accuracy better than 1 μs and at least three output channels. These channels send control signals to control the output switches of the laser module and the microwave module, as well as the playback of the microwave system's set frequency list. The frequencies in the set frequency list are between 2-4 GHz, the number of frequencies in the set frequency list is between 10-200, and the frequency interval is between 10-1000 kHz. The external trigger interface of the arbitrary sequence generator is connected to the trigger output of the scientific camera and can receive trigger pulse signals to output pulses. The pulse output sequence is described as follows: a. After receiving the trigger pulse, the channels controlling the output switch of the laser module and the channel controlling the output switch of the microwave module are both at high level, while other channels are at low level. The time length t is the same as or less than the exposure time of each frame, and is used to collect fluorescence signals. This process is repeated n times, where 1≤n≤1000. b. After receiving the trigger pulse again, the channel controlling the output switch of the laser module is at a high level, and the other channels are at a low level. The time length is the same as t, which is used to collect the fluorescence reference signal. This process is repeated n times. c. Repeat a and b m times, where 1 ≤ m ≤ 1000; d. The channel controlling the output switch of the microwave module is at a high level to trigger the microwave module to change its frequency; f. Step ad is repeated l times, where l is an integer multiple of the number of frequencies in the frequency list; One side opening of the radiating structure serves as a laser guide hole for the laser beam. A through-hole is located at the end of the laser guide hole, and an Ω-shaped copper-clad conductor is installed on the through-hole. This copper-clad conductor is used to generate a microwave magnetic field under the influence of a microwave signal. The radiating structure is positioned between the objective lens and the diamond NV center spin sensor via a fixed bracket, ensuring that the radiating structure does not contact the diamond NV center spin sensor or the objective lens. The diamond NV center spin sensor has a length not exceeding 3 mm and a thickness not exceeding 1 mm, and has a beveled surface on one side. The angle between the beveled surface and the horizontal direction is between 35 and 55 degrees. The sample is placed on the sample stage of the probe module together with the diamond NV center spin sensor. The laser beam is coupled into a multimode homogenizing fiber via a coupling device, and then focused onto the beveled surface of the diamond NV center spin sensor by a beam focuser.

2. In the quantum wide-field magnetic microscope according to claim 1, the diamond NV center is located on the side of the diamond NV center spin sensor closer to the sample to be tested, and it converts the magnetic field signal of the sample to be tested into a fluorescence signal through quantum effect.

3. The quantum wide-field magnetic microscope according to claim 1, wherein the probe module further includes a Helmholtz coil for applying a uniform external magnetic field of adjustable magnitude and direction to the sample to be tested.

4. The quantum wide-field magnetic microscope according to claim 1, wherein the excitation optical path module includes a laser, a multimode homogenizing fiber, and an angle-adjustable beam focuser. The laser is coupled into the multimode homogenizing fiber through a coupling device, and then the laser of the multimode homogenizing fiber is focused by the beam focuser to irradiate the oblique surface of the diamond NV color center spin sensor, thereby acting on the side with the diamond NV color center to form a light spot with uniform power density.

5. The quantum wide-field magnetic microscope according to claim 1, wherein the fluorescence imaging module includes a CCD or sCMOS type scientific camera, and the completed exposure preparation of the scientific camera is connected to the external trigger interface of an arbitrary sequence generator.

Images