Wide-field dynamic magnetic imaging device and method

Abstract

The invention provides a wide-field dynamic magnetic imaging device and method, and the device comprises a probe assembly which comprises a diamond containing an NV color center; the microwave magnetic field assembly is suitable for generating a uniform microwave field and a uniform bias magnetic field near the diamond so as to regulate and control the spin energy level and the quantum state evolution process of the diamond; the laser modulation assembly is suitable for outputting initial uniform pulse laser to excite the diamond to emit fluorescent light; the stripe light modulation assembly is suitable for modulating the initial uniform pulse laser to output stripe pulse laser, so that fluorescent light emitted by the diamond is stripe fluorescent light; or modulating the fluorescence emitted by the diamond into stripe fluorescence; the fluorescence detection assembly is suitable for carrying out space imaging on the stripe fluorescence to obtain magnetic field information of the to-be-detected sample and further obtain an initial magnetic image of the to-be-detected sample; and a data processing component suitable for performing Fourier transform and inverse Fourier transform processing on the initial magnetic image to obtain a first magnetic image.

Description

Technical Field

[0001] At least one embodiment of the present disclosure relates to the technical field of wide-field quantum magnetic imaging, and more specifically to a wide-field dynamic magnetic imaging device and method. Background Art

[0002] NV color centers are atomic-scale point defects in diamonds. Due to their powerful performance at room temperature, they have been applied to biological systems, integrated circuits, materials science, earth science, positioning and navigation, quantum information, and other fields. Quantum diamond microscopy uses optical initialization and readout of NV electron spin states to measure spatial distribution images of multiple physical quantity parameters (such as vector magnetic fields) in parallel. Due to the small size of NV color centers, they can be placed near the sample to be measured, thereby performing high spatial resolution magnetic field measurements.

[0003] Quantum diamond microscopy technology has made rapid progress in the past decade, and the measurement time bandwidth has gradually developed from static magnetic field measurement (DC) to dynamic magnetic field imaging (kHz). In order to obtain wide-field magnetic field images, quantum diamond microscopy technology uses cameras (such as electron-coupled devices CCD, or complementary metal oxide semiconductor CMOS, etc.) to collect NV color center fluorescence carrying electromagnetic signals. The readout speed of the camera also determines the upper limit of the time resolution of quantum diamond microscopy (~10 ms), which limits the technology's ability to detect high-frequency dynamic signals. In order to meet the needs of dynamic magnetic imaging, in recent years, some researchers have used phase-locked cameras in quantum diamond microscopes for fluorescence collection and imaging, achieving a maximum time resolution of 0.4 ms. However, phase-locked cameras require high NV fluorescence intensity, and the time resolution is highly dependent on the fluorescence intensity. For example, in this work, in order to achieve a time resolution of 0.4 ms, the NV color center density used was high (about 0.1-1 ppm) and the thickness was 40 microns, so its spatial resolution was much greater than the optical diffraction limit. This makes the technology difficult to apply in low-light scenarios. For example, when high spatial resolution is required, the thickness of the NV center is only tens of nanometers to micrometers. At this time, the number of photoelectrons caused by the NV center fluorescence on the millisecond time scale is difficult to meet the detection threshold of the phase-locked camera, so it is difficult to achieve high temporal resolution.

[0004] In the existing quantum diamond microscopy technology, under the requirement of high spatial resolution, the thickness of the NV center is only tens of nanometers to micrometers. At this time, the number of photoelectrons caused by the NV center fluorescence on the millisecond time scale is difficult to meet the detection threshold of the phase-locked camera, and it is difficult to achieve sub-millisecond to microsecond time-resolved measurement of high-frequency dynamic signals under the requirement of high spatial resolution. Summary of the invention

[0005] In order to solve at least one of the above-mentioned and other technical problems in the prior art, the present disclosure provides a wide-field dynamic magnetic imaging device and method, which can achieve sub-millisecond to microsecond time-resolved measurement of high-frequency dynamic signals under the requirement of high spatial resolution.

[0006] According to one aspect of the present disclosure, there is provided a wide-field dynamic magnetic imaging device, comprising:

[0007] A probe assembly including a diamond containing NV color centers;

[0008] A microwave magnetic field assembly, adapted to generate a uniform microwave field and a uniform bias magnetic field near the diamond to regulate the spin energy level and quantum state evolution process of the diamond;

[0009] A laser modulation component, adapted to output an initial uniform pulse laser to excite the diamond to emit fluorescence, wherein the fluorescence includes magnetic field information of the sample to be tested;

[0010] A stripe light modulation component is used to modulate the initial uniform pulse laser to output a stripe pulse laser so that the fluorescence emitted by the diamond is stripe fluorescence; or directly modulate the fluorescence emitted by the diamond into stripe fluorescence;

[0011] A fluorescence detection component, adapted to perform spatial imaging of the stripe fluorescence to obtain magnetic field information of the sample to be tested, and further obtain an initial magnetic image of the sample to be tested; and

[0012] A data processing component, adapted to perform Fourier transform and inverse Fourier transform on the initial magnetic image to obtain a first magnetic image;

[0013] The initial magnetic image includes a two-dimensional real space image obtained by superimposing sub-two-dimensional real space images obtained at multiple moments, and the first magnetic image includes multiple sub-two-dimensional real space images corresponding to the multiple moments respectively.

[0014] According to an embodiment of the present disclosure, a microwave magnetic field component is arranged to generate a uniform microwave field and a uniform bias magnetic field near a diamond containing an NV color center contained in a probe component to regulate the spin energy level and quantum state evolution process of the diamond; a laser modulation component is arranged to output an initial uniform pulse laser to excite the diamond to emit fluorescence, and the fluorescence includes magnetic field information of the sample to be tested; a stripe light modulation component is arranged to modulate the initial uniform pulse laser to output a stripe pulse laser, so that the fluorescence emitted by the diamond is stripe fluorescence; or the stripe light modulation component modulates the fluorescence emitted by the diamond into stripe fluorescence; a fluorescence detection component is arranged to perform spatial imaging of the stripe fluorescence to obtain the magnetic field information of the sample to be tested, and then obtain an initial magnetic image of the sample to be tested; and a data processing component is arranged to perform Fourier transform and inverse Fourier transform processing on the initial magnetic image to obtain a first magnetic image; the initial magnetic image includes a two-dimensional real space image obtained by superimposing sub-two-dimensional real space images obtained at multiple moments, and the first magnetic image includes multiple sub-two-dimensional real space images corresponding to the multiple moments respectively. The present invention realizes sub-millisecond to microsecond time-resolved measurement of high-frequency dynamic signals under the requirement of high spatial resolution through the mutual cooperation between various components in a wide-field dynamic magnetic imaging device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above contents and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0016] Figure 1 Schematically showing an experimental sequence diagram of high-speed signal acquisition by Fourier k-space encoding in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure;

[0017] Figure 2 The working principle diagram of the probe assembly in the wide-field dynamic magnetic imaging device according to the embodiment of the present disclosure is schematically shown;

[0018] Figure 3 A schematic diagram showing the relative positions of a diamond containing NV color centers and a uniform radiation structure in a probe assembly in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure is shown;

[0019] Figure 4 A block diagram schematically shows a microwave magnetic field component in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure;

[0020] Figure 5 A block diagram schematically shows a laser modulation component in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure;

[0021] Figure 6 A block diagram schematically shows a stripe light modulation component in a wide-field dynamic magnetic imaging device according to another embodiment of the present disclosure;

[0022] Figure 7 A schematic diagram showing the principle of modulating stripe light by a stripe light modulation component in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure;

[0023] Figure 8 A block diagram schematically shows a fluorescence detection component in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure;

[0024] Fig. 9 A schematic diagram of the optical path for generating and collecting fringe fluorescence in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure is shown;

[0025] Fig.10 Schematically shows a schematic diagram of the optical path for generating and collecting stripe fluorescence in a wide-field dynamic magnetic imaging device according to another embodiment of the present disclosure;

[0026] Fig.11 The working principle diagram of the temperature control component in the wide-field dynamic magnetic imaging device according to the embodiment of the present disclosure is schematically shown;

[0027] Fig.12 A diagram schematically shows the position relationship between the position adjustment component, the probe component, and the sample to be measured in the wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure;

[0028] Fig.13 A flowchart schematically shows a wide-field dynamic magnetic imaging method according to an embodiment of the present disclosure; and

[0029] Fig.14 The flowchart schematically shows a method for wide-field dynamic magnetic imaging according to an embodiment of the present disclosure, which uses a data processing component to perform Fourier transform and inverse Fourier transform on an initial magnetic image to obtain a first magnetic image.

[0030] In the above drawings, the meanings of the reference numerals are as follows:

[0031] 1-Probe assembly;

[0032] 101- Diamond containing NV color centers;

[0033] 102-uniform radiation structure;

[0034] 2- Microwave magnetic field assembly;

[0035] 201-microwave source;

[0036] 202-microwave beam splitter;

[0037] 203-microwave switch;

[0038] 204-microwave combiner;

[0039] 205-microwave amplifier;

[0040] 206-Isolator;

[0041] 207-impedance matching;

[0042] 208-magnetic field source;

[0043] 3-Laser modulation assembly;

[0044] 301-Laser;

[0045] 302-first half-wave plate;

[0046] 303-Acousto-optic modulator group;

[0047] 304- lens group;

[0048] 3041-first convex lens;

[0049] 3042- second convex lens;

[0050] 305- beam shaper;

[0051] 306-second half-wave plate;

[0052] 307-first reflection component;

[0053] 3071-first reflector;

[0054] 3072-second reflector;

[0055] 4- Stripe light modulation component;

[0056] 401-Digital micromirror device;

[0057] 402-first lens;

[0058] 403-Filter;

[0059] 404- second lens;

[0060] 5-fluorescence detection component;

[0061] 501-imaging lens;

[0062] 502-multi-stage filter;

[0063] 503-fluorescence detector;

[0064] 6-Data processing component;

[0065] 7-sample to be tested;

[0066] 8-substrate;

[0067] 9- Temperature control component;

[0068] 901- Temperature monitor;

[0069] 902-temperature control box;

[0070] 903-temperature controller;

[0071] 10-Objective lens;

[0072] 11- first focusing lens;

[0073] 12- third reflector;

[0074] 13- dichroic mirror;

[0075] 14-achromatic lens;

[0076] 15-position adjustment component;

[0077] 151- Z-axis position adjustment device;

[0078] 152-two-axis position adjustment device;

[0079] 153-three-axis position adjustment device;

[0080] 1531-Three-axis large-range position adjustment device;

[0081] 1532-Three-axis small-range position adjustment device. DETAILED DESCRIPTION

[0082] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0083] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0084] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0085] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0086] In the existing quantum diamond microscopy technology, under the requirement of high spatial resolution, the thickness of the NV center is only tens of nanometers to micrometers. At this time, the number of photoelectrons caused by the NV center fluorescence on the millisecond time scale is difficult to meet the detection threshold of the phase-locked camera, and it is difficult to achieve sub-millisecond to microsecond time-resolved measurement of high-frequency dynamic signals under the requirement of high spatial resolution.

[0087] In view of this, the present disclosure provides a wide-field dynamic magnetic imaging device, which generates a uniform microwave field and a uniform bias magnetic field near a diamond containing an NV color center contained in a probe assembly by setting a microwave magnetic field component to regulate the spin energy level and quantum state evolution process of the diamond; a laser modulation component is set to output an initial uniform pulse laser to excite the diamond to emit fluorescence, and the fluorescence includes the magnetic field information of the sample to be tested; a stripe light modulation component is set to modulate the initial uniform pulse laser to output a stripe pulse laser, so that the fluorescence emitted by the diamond is stripe fluorescence; or the stripe light modulation component modulates the fluorescence emitted by the diamond into stripe fluorescence; a fluorescence detection component is set to perform spatial imaging of the stripe fluorescence to obtain the magnetic field information of the sample to be tested, and then obtain an initial magnetic image of the sample to be tested; and a data processing component is set to perform Fourier transform and inverse Fourier transform processing on the initial magnetic image to obtain a first magnetic image; the initial magnetic image includes a two-dimensional real space image obtained by superimposing sub-two-dimensional real space images obtained at multiple moments, and the first magnetic image includes multiple sub-two-dimensional real space images corresponding to the multiple moments respectively. The present invention realizes sub-millisecond to microsecond time-resolved measurement of high-frequency dynamic signals under the requirement of high spatial resolution through the mutual cooperation between various components in a wide-field dynamic magnetic imaging device.

[0088] According to some embodiments of the present disclosure, the wide-field dynamic magnetic imaging device includes a probe assembly, a microwave magnetic field assembly, a laser modulation assembly, a stripe light modulation assembly, a fluorescence detection assembly, and a data processing assembly. The probe assembly includes a diamond containing an NV color center; the microwave magnetic field assembly is suitable for generating a uniform microwave field and a uniform bias magnetic field near the diamond to regulate the spin energy level and quantum state evolution process of the diamond; the laser modulation assembly is suitable for outputting an initial uniform pulse laser to excite the diamond to emit fluorescence, and the fluorescence includes the magnetic field information of the sample to be tested; the stripe light modulation assembly is suitable for modulating the initial uniform pulse laser to output a stripe pulse laser so that the fluorescence emitted by the diamond is stripe fluorescence; or the fluorescence emitted by the diamond is directly modulated into stripe fluorescence. The fluorescence detection assembly is suitable for spatial imaging of the stripe fluorescence to obtain the magnetic field information of the sample to be tested, and then obtain the initial magnetic image of the sample to be tested; and the data processing assembly is suitable for Fourier transform and inverse Fourier transform processing of the initial magnetic image to obtain a first magnetic image.

[0089] According to some embodiments of the present disclosure, the initial magnetic image includes a two-dimensional real-space image obtained by superimposing sub-two-dimensional real-space images obtained at multiple moments, and the first magnetic image includes multiple sub-two-dimensional real-space images corresponding to the multiple moments respectively.

[0090] According to some embodiments of the present disclosure, a microwave magnetic field component is arranged to generate a uniform microwave field and a uniform bias magnetic field near a diamond containing an NV color center included in a probe component to regulate the spin energy level and quantum state evolution process of the diamond; a laser modulation component is arranged to output an initial uniform pulse laser to excite the diamond to emit fluorescence, and the fluorescence includes magnetic field information of the sample to be tested; a stripe light modulation component is arranged to modulate the initial uniform pulse laser to output a stripe pulse laser, so that the fluorescence emitted by the diamond is stripe fluorescence; or the stripe light modulation component modulates the fluorescence emitted by the diamond into stripe fluorescence; a fluorescence detection component is arranged to perform spatial imaging of the stripe fluorescence to obtain the magnetic field information of the sample to be tested, and then obtain an initial magnetic image of the sample to be tested; and a data processing component is arranged to perform Fourier transform and inverse Fourier transform processing on the initial magnetic image to obtain a first magnetic image; the initial magnetic image includes a two-dimensional real space image obtained by superimposing sub-two-dimensional real space images obtained at multiple moments, and the first magnetic image includes multiple sub-two-dimensional real space images corresponding to multiple moments respectively; sub-millisecond to microsecond time-resolved measurement of high-frequency dynamic signals under the requirement of high spatial resolution is realized.

[0091] According to some embodiments of the present disclosure, the temporal resolution is limited by the signal acquisition speed. Taking wide-field imaging as an example, the camera's shooting speed determines the time interval between two adjacent frames of the picture, so the highest temporal resolution of the imaging is the camera frame rate. In order to obtain dynamic images with high temporal resolution, the number of pixels for collecting light signals can be reduced, thereby reducing the readout time, but this will reduce the imaging field of view, resulting in a reduction in the flux of wide-field imaging, which is not conducive to the imaging requirements of a large field of view. In order to retain the advantage of wide-field imaging that the flux is much greater than scanning imaging, while improving the temporal resolution of imaging, non-uniform illumination can be used to encode images of different time periods at different positions in the k-space, and then reconstruct the dynamic image information through Fourier transform and spatial filtering.

[0092] The core component of widefield imaging is a microscope system. As a linear translation-invariant system, the imaging process can be described by the point spread function, which can be expressed as formula (1): (1);

[0093] in, represents the light field intensity distribution on the image plane, which represents the fluorescence distribution image of the sample obtained by the microscope system. Indicates the light field intensity distribution of the sample surface emission light. For NV-based wide-field magnetic imaging, the fluorescence is emitted by the NV color center, so the fluorescence intensity It is related to the spatial distribution of NV color centers. represents the point spread function of the microscope system, Represents a convolution operation.

[0094] Under uniform illumination conditions, the light field intensity of the sample emitted light is The spatial variation of is only related to the spatial distribution of NV color centers and the population of quantum states. In the context of magnetic imaging applications, the population is related to the external magnetic field B(t). Here, the two factors are combined and recorded as , assuming that the excitation light illumination intensity is I0 and the fluorescence collection efficiency of the microscope system for NV is α, the light field intensity of the sample emission light can be expressed as formula (2):

[0095] (2);

[0096] In this case, due to the slow camera readout, the fluorescence distribution caused by the dynamic magnetic signals at different moments are accumulated in one picture (i.e., the initial magnetic image), resulting in a low temporal resolution.

[0097] If non-uniform excitation light is used to illuminate the NV color center, the fluorescence light field emitted by the sample and NV color center distribution It is linearly related to the intensity distribution of the illumination light field, and the linear relationship satisfies formula (3): (3);

[0098] Substituting formula (3) into formula (1) and performing Fourier transform, we can obtain formula (4): (4);

[0099] in, represents the optical transfer function of the microscope system, which is the Fourier transform of the point spread function , It represents the limitation of the amount of information passing through the microscope system, which only allows low-frequency information to pass through the system, and high-frequency information is cut off.

[0100] Now, using the cosine form of excitation light to illuminate the NV color center, the excitation light field intensity can be expressed as formula (5): (5);

[0101] in, and denote the average intensity and initial phase of the cosine illumination fringes, respectively, Indicates the magnitude and direction of the spatial frequency of the cosine fringe, and its modulus is the inverse of the fringe period. Through Fourier transform, the expression of cosine fringe in the frequency domain can be obtained as formula (6):

[0102] (6).

[0103] From this we can see that is the delta function at three positions in the frequency domain. Substituting formula (6) into formula (4), we can obtain the spectrum information of the image plane fluorescence image. The spectrum information of the image plane fluorescence image satisfies formula (7):

[0104] (7).

[0105] Formula (6) and formula (7) show that the role of the cosine fringe illumination light is to copy the spectrum of the fluorescence image into three in the frequency domain, which is expressed as formula (8), (9) and (10):

[0106] (8);

[0107] (9);

[0108] (10);

[0109] The zero frequency position of one of them is located at the origin of the frequency domain, and the zero frequency positions of the other two are moved to and The frequency domain signal at each position contains the complete spectrum information of the fluorescence image.

[0110] It can be seen from formula (7) that cosine fringe illumination can move the image spectrum information to a specified position in k-space (i.e., frequency domain). Therefore, by adjusting the size and direction of the fringe spatial frequency, the image information at different times can be encoded to different positions in k-space, thereby achieving time-resolved imaging of dynamic images.

[0111] By using a digital micromirror device (DMD) 401 to generate an adjustable grating to modulate the stripe illumination light and realizing rapid switching of the stripes through electric pulses, it is possible to obtain image information at a specified moment at a speed much higher than the camera frame rate, thereby achieving high time-resolution dynamic magnetic imaging and breaking through the limitation of the camera readout speed on the time resolution of the quantum diamond microscope.

[0112] Figure 1 The experimental sequence diagram of implementing high-speed signal acquisition by Fourier k-space encoding in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure is schematically shown.

[0113] According to some embodiments of the present disclosure, in order to obtain dynamic magnetic images with high temporal resolution, fluorescence measurement uses an electron-coupled device or a complementary metal oxide semiconductor camera used in a general quantum diamond microscope as a fluorescence detector. Figure 1 The stripe pattern in the middle is a schematic diagram of the two-dimensional grating pattern loaded by the digital micromirror device. The switching of the stripe pattern is controlled by the trigger signal. The microwave pulse is represented by the shaded square, and π / 2 represents the microwave pulse length. Figure 1 As shown, during the exposure of a camera image, m fringe images are switched, and all NV color center fluorescence counts generated during the exposure period are collected into one image. This image can be expressed by formula (11): (11);

[0114] in It represents the mth cosine fringe illumination light played in time sequence, Indicates different moments ( ) The spatial distribution and quantum state population of the NV color center, which records the spatial magnetic field information recorded by the NV color center at different times. The frequency domain signal obtained by Fourier transforming formula (11) is expressed as formula (12):

[0115] (12)

[0116] Formula (11) and Formula (12) indicate that magnetic field images acquired at different times can be superimposed in the same image. Although magnetic field images at different times cannot be distinguished in real space, the image spectrum information at different times in k-space is separable, so images at different times can be distinguished in the frequency domain.

[0117] According to some embodiments of the present disclosure, Figure 1 In the magnetic imaging pulse sequence, three different magnetic field measurement pulse sequences are listed, namely the Ramsey sequence, the Rabi oscillation and the continuous wave spectrum sequence. During the signal measurement process, different sequences can be selected to match the measurement of different signals. In general, the quantum state of the NV color center is initialized by laser and microwave, and the magnetic field to be measured causes the quantum state of the NV color center to evolve to the final state, and then the quantum state occupancy is read out by laser to obtain the magnetic field information. Different magnetic fields cause different NV color center occupancy, which causes different NV color center fluorescence intensities. Through wide-field imaging, the magnetic field size at different positions can be obtained, and the rapid fluorescence signal readout can obtain the relationship between the magnetic field and time.

[0118] The following uses these three sequences as examples to illustrate the principle of magnetic field measurement.

[0119] Ramsey sequence: laser initialization pulse—π / 2 microwave pulse—free evolution—π / 2 microwave pulse—laser readout pulse. First, the laser pulse initializes the NV color center to state, and then a π / 2 microwave pulse flips the NV to state, and then the NV evolves freely under the external magnetic field B(t), accumulating the phase ,in is the gyromagnetic ratio of the NV color center, for The magnitude of the external magnetic field at that moment, is the free evolution time. After the free evolution is completed, the NV center is prepared to state, and then a π / 2 microwave pulse flips the NV to Finally, the NV color center is read out using a laser pulse. Population .

[0120] Rabi oscillation sequence: laser initialization pulse - variable length microwave pulse - laser readout pulse. This method can measure the spatial distribution of high-frequency electromagnetic field intensity in the order of hundreds of MHz to GHz. The measured field is then applied to drive the energy level resonance of the NV center. The fluorescence of the NV center will change with the duration of the driving field application, and the frequency of the Rabi oscillation ,in The field is linearly related to the microwave magnetic field .

[0121] Continuous wave spectrum sequence: continuous laser and continuous microwave are applied simultaneously. According to the Zeeman effect, the external magnetic field causes the NV energy level to split. The energy level interval is Therefore, by measuring the resonance spectrum and determining the energy level of the NV color center, the magnetic field along the NV axis can be obtained. .

[0122] According to the embodiment of the present disclosure, it can be known from formula (12) that the frequency domain signals of the magnetic image at different times are encoded in different regions of the k-space, so the image can be reconstructed in combination with spatial filtering in the frequency domain. The inverse solution process includes steps 1 to 4.

[0123] In step 1, two-dimensional real space image acquisition is performed as follows: Figure 1 The fluorescence image is collected according to the experimental sequence shown in , and finally a cumulative fluorescence image encoded by multiple cosine fringes is obtained, which is the initial magnetic image.

[0124] In step 2, the initial magnetic image is Fourier transformed to obtain a frequency domain signal and a two-dimensional k-space image. The theoretical expression of step 2 is formula (12).

[0125] In step 3, the image frequency domain signals at different times in the two-dimensional k-space image are separated, and a k-space filter is constructed for each image at each time, and its center position is , with a width of W, which satisfies , that is, the filter width is less than or equal to the spatial frequency difference between the two fringes with the closest period and direction, so as to ensure that the separated signal will not be interfered by fringes in other directions; after applying the k-space filter to all cosine fringes, M two-dimensional k-space frequency domain signals are obtained, representing the frequency domain signals at different times.

[0126] In step 4, the zero frequency position of the two-dimensional frequency domain signal corresponding to each stripe is changed from Move to the origin of the two-dimensional k-space, and then perform inverse Fourier transform to obtain the real-space image of each fringe code, that is, the two-dimensional real-space magnetic field map at the corresponding moment, that is, the first magnetic image including multiple sub-two-dimensional real-space images corresponding to multiple moments.

[0127] Figure 2 The working principle diagram of the probe assembly in the wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure is schematically shown.

[0128] According to some embodiments of the present disclosure, Figure 2 As shown, the probe assembly 1 further includes a uniform radiation structure 102 , which is suitable for providing a microwave field to change the spin quantum state of the NV color center in the diamond 101 .

[0129] According to some embodiments of the present disclosure, a microwave field is provided by arranging a uniform radiation structure 102 to change the spin quantum state of the NV color center in the diamond 101 .

[0130] According to some embodiments of the present disclosure, the uniform microwave field generated by the uniform radiation structure 102 has a range of the order of 100 microns, and the uniformity of the microwave field can reach more than 95%, thereby ensuring that all NV color centers are affected in the same way, thereby improving the accuracy of manipulating the spin quantum state of the NV color center in the diamond 101.

[0131] According to some embodiments of the present disclosure, Figure 2 As shown, the substrate 8 is disposed below the sample 7 to be tested, and the substrate 8 is suitable for supporting the sample 7 to be tested.

[0132] Figure 3 The diagram schematically shows the relative positions of the diamond containing NV color centers and the uniform radiation structure in the probe assembly in the wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure.

[0133] According to some embodiments of the present disclosure, Figure 3 As shown, the diamond containing NV color centers is arranged at a centrally symmetrical position of the uniform radiation structure.

[0134] According to some optional embodiments of the present disclosure, the uniform radiation structure 102 is a waveguide, and uniform distribution of the microwave field in the diamond region containing NV color centers can be achieved by setting the shape of the waveguide.

[0135] According to some embodiments of the present disclosure, the surface of the diamond 101 containing NV color centers is flat and includes multiple NV color centers, which form a thin layer inside the diamond 101; the depth difference between two adjacent NV color centers is less than 10 microns, and the distance between two adjacent NV color centers in the horizontal direction is less than the optical diffraction limit.

[0136] According to some embodiments of the present disclosure, the surface of the diamond 101 containing the NV color center is flat, which can improve the accuracy of sensing the external magnetic field. In addition, the diamond 101 containing the NV color center has no surface structure, that is, the diamond 101 has fewer internal defects and impurities, which reduces the interference with the quantum state. Marking a specific position of the diamond 101 (such as the position of the NV color center center) can improve the accuracy of the recognition of the sensing area, and facilitate the initialization, manipulation and reading of the quantum state of the NV color center.

[0137] According to some embodiments of the present disclosure, by setting the depth difference between two adjacent NV centers to be less than 10 microns, the distance between two adjacent NV centers in the horizontal direction is less than the optical diffraction limit, and making all NV centers in the diamond 101 satisfy this arrangement, the uniformity and consistency of quantum sensing are improved. When the depth difference between all NV centers is less than 10 microns, the influence of the diamond lattice on all NV centers is similar, further enhancing the uniformity of sensing. When the horizontal spacing of all NV centers is less than the optical diffraction limit of the system, a smaller spot can be used to excite multiple NV centers individually or simultaneously, thereby improving the resolution and sensitivity of optical measurement. All NV centers satisfying this arrangement also improve the control efficiency of the microwave field, so that the microwave field can act more evenly on all NV centers.

[0138] According to some embodiments of the present disclosure, when multiple NV color centers are formed inside the diamond 101 with a certain density and arrangement, they can form a two-dimensional thin layer. The thin layer may be located near the surface of the diamond 101, or it may be at a certain depth inside the diamond 101. Due to the optical and quantum properties of the NV color center itself, the thin layer composed of the NV color center also exhibits similar properties. For example, the thin layer may exhibit strong fluorescence under laser pumping, and its fluorescence properties can be regulated by controlling factors such as temperature. Since the spin state of the NV color center can be operated and detected by lasers and microwaves, the thin layer can be used as a two-dimensional quantum bit array to implement various quantum information processing tasks.

[0139] Figure 4 The block diagram schematically shows a microwave magnetic field component in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure.

[0140] According to some embodiments of the present disclosure, Figure 4 As shown, the microwave magnetic field component 2 includes: a microwave source 201, a microwave beam splitter 202, a microwave switch 203, a microwave combiner 204, a microwave amplifier 205, an isolator 206, an impedance match 207 and a magnetic field source 208. The microwave source 201 is suitable for generating an initial microwave of a specific frequency and power; the microwave beam splitter 202 is suitable for dividing the initial microwave into two first microwaves with equal power and a phase difference of 90°; the microwave switch 203 is suitable for controlling the on-off of the transmission paths of the two first microwaves; the microwave combiner 204 is suitable for combining the two first microwaves into one second microwave; the microwave amplifier 205 is suitable for amplifying the power of the second microwave to obtain a third microwave, and the third microwave enters the uniform radiation structure 102; the isolator 206 is suitable for preventing the third microwave from reflecting and entering the microwave amplifier 205; the impedance match 207 is suitable for reducing the loss of the third microwave during transmission; and the magnetic field source 208 is suitable for providing a uniform bias magnetic field.

[0141] According to some embodiments of the present disclosure, the microwave field and bias magnetic field generated are regulated by setting the microwave magnetic field assembly 2 to ensure a uniform microwave field and uniform bias magnetic field environment near the diamond 101. According to the frequency and power requirements of the target uniform microwave field, a suitable microwave source 201 capable of generating the frequency and power of the target uniform microwave field is selected, and the initial microwave of the specific frequency and power includes the frequency and power of the target uniform microwave field, and the frequency range of the initial microwave is generally between 300 MHz and 300 GHz.

[0142] According to some embodiments of the present disclosure, the uniform microwave field is within the diamond NV color center region; and the direction of the bias magnetic field is along the direction of the NV color center axis.

[0143] According to some embodiments of the present disclosure, Figure 4 As shown, the microwave switch 203 includes a first microwave switch 2031 and a second microwave switch 2032. The microwave switch 203 is used to control the on and off of the transmission paths of the two first microwaves, so as to realize flexible control of the transmission of microwave signals. The power of the second microwave is amplified by the microwave amplifier 205 to obtain the third microwave, so as to ensure that the power of the third microwave can generate power that meets the target uniform microwave field after entering the uniform radiation structure 102. The isolator 206 is used to prevent the third microwave from being reflected and entering the microwave amplifier, and at the same time, the microwave amplifier 205 is prevented from being damaged. The impedance matching 207 is used to ensure that the impedance change encountered by the microwave signal during the transmission process is minimized, thereby reducing the loss during the transmission of the third microwave. The impedance matching 207 is arranged at the end of the entire line of the microwave magnetic field component 2 to protect the microwave line.

[0144] According to some embodiments of the present disclosure, impedance matching 207 means that the characteristic impedance of the connected transmission line is equal in magnitude and phase to the internal resistance of the microwave source 201, or the characteristic impedance of the transmission line is equal in magnitude and phase to the connected load impedance (i.e., uniform radiation structure), so as to ensure maximum power transmission of the microwave signal and reduce reflection loss of the microwave signal.

[0145] According to some embodiments of the present disclosure, the microwave source 201 includes any one of a semiconductor device and a resonant cavity; the magnetic field source 208 includes any one of a coil and a large permanent magnet. The microwave source 201 generates a spatially uniform microwave field near the diamond 101; the magnetic field source 208 generates a spatially uniform bias magnetic field near the diamond 101. The uniform range of the bias magnetic field is on the order of 1 mm, and the uniformity of the uniform bias magnetic field can reach more than 95%; the uniform microwave field generated by the uniform radiation structure 102 has a range of 100 microns, and the uniformity of the microwave field can reach more than 95%, and the uniformity of the microwave field within a range of 500 microns reaches about 99.5%.

[0146] Figure 5The block diagram schematically shows a laser modulation component in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure.

[0147] According to some embodiments of the present disclosure, Figure 5 As shown, the laser modulation component 3 includes: a laser 301, a first half-wave plate 302, an acousto-optic modulator group 303, a lens group 304 and a beam shaper 305. The laser 301 is suitable for outputting an initial continuous laser; the first half-wave plate 302 is suitable for adjusting the polarization direction of the initial continuous laser to obtain a first continuous laser; the acousto-optic modulator group 303 is suitable for modulating the first continuous laser to obtain an initial pulse laser to improve the switching ratio of the initial pulse laser; the lens group 304 is suitable for adjusting the beam diameter of the initial pulse laser; the beam shaper 305 is suitable for converting the beam of the initial pulse laser into a flat-top beam with uniform light intensity distribution to output an initial uniform pulse laser.

[0148] According to some embodiments of the present disclosure, the initial continuous laser is a linearly polarized Gaussian beam having a Gaussian intensity distribution and a linearly polarized polarization state. The laser power of the initial continuous laser is in the order of 1 to 5 W. The acousto-optic modulator (Acousto-Optic The AOM (Acousto-Optic Modulator) group is a structure in which multiple acousto-optic modulators are cascaded. The acousto-optic modulator group modulates the first continuous laser through an external modulation signal, and can control the on and off of the first continuous laser transmission path, thereby obtaining an initial pulse laser. The lens group 304 includes a first convex lens 3041 and a second convex lens 3042. The rear focal plane of the first convex lens 3041 coincides with the front focal plane of the second convex lens 3042 to form a confocal relationship, so that the incident nearly parallel laser beam is emitted in the same nearly parallel state after the beam diameter is adjusted by the lens group 304. The output beam diameter is equal to the incident beam diameter multiplied by the ratio of the focal length of the second convex lens 3042 to the focal length of the first convex lens 3041. The beam diameter is adjusted by selecting a suitable focal length. The beam shaper 305 is a diffractive optical element, such as a flat-top beam shaper, which converts the initial pulse laser into an initial uniform pulse laser. The light intensity of the initial uniform pulse laser is uniformly distributed.

[0149] According to some optional embodiments of the present disclosure, the laser 301 generates an initial continuous laser with a power of 1 watt and a wavelength of 532 nanometers; the acousto-optic modulator group is a cascade configuration of three acousto-optic modulators, and the acousto-optic modulator group can make the overall switching ratio as high as 10 7 : 1. The efficiency of converting the first continuous laser into the initial pulse laser is improved, and the loss of the first continuous laser signal is reduced; the uniformity of the initial uniform pulse laser is about 90%.

[0150] Figure 6The block diagram schematically shows a stripe light modulation component in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure.

[0151] According to some embodiments of the present disclosure, Figure 6 As shown, the stripe light modulation component 4 includes: a digital micromirror device 401, 4f optical systems 402, 404 and a filter 403. The digital micromirror device 401 is suitable for diffracting the initial uniform pulse laser into multiple beams of parallel light propagating in different directions; the 4f optical systems 402, 404 are suitable for converting the multiple beams of parallel light into stripe light, and the stripe light presents a two-dimensional distribution of light and dark stripes on the output plane; the filter 403 is arranged in the 4f optical systems 402, 404, and the filter 403 is suitable for filtering out stray light in the multiple beams of parallel light.

[0152] According to some embodiments of the present disclosure, a digital micromirror device (DMD) is a micro-mirror array, each of which can be independently tilted to two different angles (e.g., +12° and -12°) to reflect light in two different directions. When parallel light is incident on the DMD, a binary grating can be formed by controlling the tilt angle of each micromirror. This binary grating is like a two-dimensional black and white chessboard, in which the white part indicates that light can pass through and the black part indicates that light is blocked. Therefore, the DMD has two states, "on" and "off". When the micromirror of the DMD is in the "on" state, light is allowed to pass through, and when the micromirror of the DMD is in the "off" state, light is blocked.

[0153] According to some embodiments of the present disclosure, the 4f optical system 402, 404 includes two lens components, a first lens 402 and a second lens 404. The focal lengths of the first lens 402 and the second lens 404 are equal, both f, and the distance between the first lens 402 and the second lens 404 is 2f; the digital micromirror device 401 is located at the front focal plane of the first lens 402, and the filter 403 is located at the back focal plane of the first lens 402. The first lens 402 performs Fourier transform on multiple beams of parallel light propagating in different directions, and forms a spectrum surface containing spatial spectrum information at the back focal plane of the first lens 402; the filter 403 filters out stray light in the multiple beams of parallel light, and filters out multi-order diffraction light in the multiple beams of parallel light; the second lens 404 images the finally formed stripe light to the output plane, and the stripe light presents a two-dimensional distribution of alternating bright and dark stripes on the output plane.

[0154] According to some embodiments of the present disclosure, when parallel light passes through the first lens 402, it forms a Fourier transform spectrum of the light field at the back focal plane of the first lens 402 (i.e., at a distance f from the first lens 402). This transform contains the spatial frequency information of the light field; the filter 403 can modify the Fourier transform spectrum, thereby changing the spatial distribution of the light field; the second lens 404 converts the filtered Fourier transform spectrum back to the light field, thereby generating the desired two-dimensional stripe light distribution on the output plane. The shape, direction, and contrast of these stripes can be controlled by adjusting the pattern of the DMD and the design of the filter 403.

[0155] According to some embodiments of the present disclosure, the stripe light modulation component 4 can modulate uniform light into stripe structured light, and the stripe contrast is greater than 50%. The stripe light modulation component 4 can also achieve fast switching of different stripes, and the switching rate can reach 50 kHz, thereby providing dynamic wide-field magnetic imaging with a time resolution of 20 microseconds. The stripe light modulation component 4 can be placed after the excitation modulation component 3 to modulate and generate stripe excitation light, and can also be placed in front of the fluorescence detection component 5 to achieve stripe modulation of fluorescence.

[0156] Figure 7 The schematic diagram shows the principle of modulating stripe light by a stripe light modulation component in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure.

[0157] According to some embodiments of the present disclosure, Figure 7 As shown, parallel light is incident on a digital micromirror device, and a binary grating is generated by the digital micromirror device 401, diffracting the incident light into multiple beams of parallel light propagating in different directions, and then Fourier space filtering is performed through 4f optical systems 402, 404 and filter 403 to generate a two-dimensional stripe light distribution on the output plane.

[0158] According to some embodiments of the present disclosure, assuming that the propagation direction of light is always in the z direction, the light field distribution of parallel incident light can be described as a light field E0 uniformly distributed in the xy plane. A DMD is placed in the front focal plane of the first lens 402, and a grating pattern is loaded. The micro-mirrors in the open state reflect the incident light into the subsequent light path. At the same time, the loaded grating distribution causes the incident light to diffract, so that the light exiting the DMD propagates in multiple directions.

[0159] The following uses the grating in the y direction as an example to illustrate the process of generating fringes. Define a coordinate system x'Oy' on the grating optical surface, and assume that the period of the loaded grating in the y' direction is T y , the width of each slit is D, and the transmittance function of DMD can be described by formula (13):

[0160] (13)

[0161] in, is the maximum number of grating periods that the DMD optical surface can accommodate, and the specific value is related to the size and direction of the grating period; is the aperture function of the DMD light-passing surface, whose size is the product of the DMD resolution M×N and the pixel period Δd, The expression of is formula (14): ,in, is a one-dimensional rectangular function.

[0162] Formula (13) indicates that the grating loaded by the DMD is a plurality of rectangular slits distributed along the y direction. After the incident light irradiates the grating, the outgoing light will be diffracted to different positions in the y direction. The light field obtained at the focal plane of the first lens 402 is the Fourier transform of the grating pattern, that is, the spatial spectrum information. The light field can be obtained by the Fourier transform of formula (13), and the transformation process can be expressed as formula (15):

[0163] (15);

[0164] in, is the light field distribution at the focal plane of the first lens 402; is the Fourier transform of the DMD clear aperture; It can be expressed as formula (16):

[0165] (16).

[0166] In order to generate streak light, a filter 403 is placed on the rear focal plane of the first lens 402 to remove the high diffraction orders and retain the ±1 order and the 0 order to enter the subsequent optical path. The light field distribution after filtering can be expressed as formula (17):

[0167] (17), where is the light field distribution after filtering.

[0168] The light field distribution formed on the rear focal plane (ie, output plane) of the second lens 404 is is the Fourier transform of formula (17), It can be expressed as formula (18):

[0169] (18), where for, It can be expressed as formula (19):

[0170] (19).

[0171] According to formula (18), the distribution of light intensity at the focal plane behind the second lens 404 can be obtained: , It can be expressed as formula (20):

[0172] (20).

[0173] According to some embodiments of the present disclosure, since the DMD is a planar array composed of multiple micromirrors, when receiving parallel light, the micromirror array acts as a two-dimensional grating, causing interference and diffraction of the outgoing light. Therefore, the outgoing light not only includes the above-mentioned target stripe light, but also includes the multi-order diffraction light caused by the periodic structure of the pixel. In order to ensure that the target stripe light is not interfered, other multi-order diffraction lights need to be filtered out. The formation principle of multi-order diffraction light is first described below, and then the filtering method of multi-order diffraction light is described.

[0174] Assuming that the side length of the DMD pixel is d and the pixel period is Δd, the transmittance function of the DMD can be expressed as formula (21):

[0175] (21), where is the aperture function of the DMD light-transmitting surface, and its expression is given by formula (14); It is a two-dimensional rectangular function, which means that the shape of a single pixel is a d×d square, and the center position is a plane coordinate system. The convolution operation represents the distribution of pixels at different positions on the DMD optical surface. represents the position distribution function of the DMD pixel array, It can be expressed as formula (22):

[0176] (twenty two).

[0177] After passing through the first lens 402, the image obtained at the rear focal plane of the first lens 402 is the Fourier transform of the DMD optical surface pattern. The complex amplitude of the light field in the focal plane is expressed as formula (23):

[0178] (23), where and They can be expressed as formulas (24) and (25) respectively:

[0179] (twenty four),

[0180] (25).

[0181] Formula (24) is processed according to the Fourier transform of the rectangular function, and the Fourier transform of the rectangular function can be expressed as formula (26):

[0182] (26).

[0183] Formula (24) is processed according to the Fourier transform formula (26) of the rectangular function to obtain formula (27):

[0184] (27).

[0185] Using the Fourier transform of the Dirac comb function, that is, formula (28):

[0186] (28).

[0187] According to the Fourier transform of the Dirac comb function (28), we can get formula (29):

[0188] (29).

[0189] Therefore, formula (29) indicates that multi-order diffraction light caused by the DMD pixel structure is obtained on the back focal plane of the first lens 402, and the intensity of each order of diffraction light is modulated by the single slit diffraction caused by the micro-mirror element.

[0190] In order to obtain the target stripe light, the redundant diffraction orders should be removed, and only the zero diffraction order with the largest intensity should be retained. Therefore, a low-pass filter, namely filter 403, can be placed on the rear focal plane of the first lens 402 to filter out the high diffraction orders. At the same time, in order to ensure that the ±1 order of the target stripe light is not filtered out, the width W of the low-pass filter is f Needs to be satisfied .

[0191] Figure 8 A block diagram schematically shows a fluorescence detection component in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure.

[0192] According to some embodiments of the present disclosure, Figure 8 As shown, the fluorescence detection assembly 5 includes: an imaging lens 501, a multi-stage filter 502 and a fluorescence detector 503. The imaging lens 501 is suitable for focusing fluorescence to form a fluorescence image; the multi-stage filter 502 is suitable for filtering out stray light signals and laser reflected from the surface of the diamond 101; the fluorescence detector 503 is suitable for converting the fluorescence signal into an electrical signal so as to obtain the magnetic field information of the sample 7 to be tested.

[0193] According to some embodiments of the present disclosure, the imaging lens 501 in the fluorescence detection assembly 5 is used to focus the fluorescence emitted by the diamond 101 to form a fluorescence image; the multi-stage filter 502 is used to filter out stray light signals and laser reflected from the surface of the diamond 101; and the fluorescence detector 503 is used to convert the fluorescence signal into an electrical signal, so that the magnetic field information of the sample 7 to be tested can be obtained.

[0194] According to some embodiments of the present disclosure, the fluorescence detector 503 can distinguish the spatial position of the NV color center based on the fluorescence signal.

[0195] According to some optional embodiments of the present disclosure, the fluorescence detector 503 includes any one of an electron coupled device and a complementary metal oxide semiconductor, and the multi-stage filter 502 includes three 900-nanometer short-pass filters.

[0196] Fig. 9 The schematic diagram of the optical path for generating and collecting stripe fluorescence in a wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure is shown schematically.

[0197] According to some embodiments of the present disclosure, Fig. 9 As shown, the laser 301 generates an initial continuous laser, the first half-wave plate 302 adjusts the polarization direction of the initial continuous laser to obtain a first continuous laser, the first continuous laser is modulated by the acousto-optic modulator group 303 to output an initial pulse laser, the lens group 304 adjusts the beam diameter of the initial pulse laser, and the initial pulse laser with the adjusted beam diameter is converted into an initial uniform pulse laser with uniform light intensity distribution by the beam shaper 305; the second half-wave plate 306 adjusts the polarization direction of the initial uniform pulse laser; the initial uniform pulse laser with changed polarization direction is reflected to the digital micromirror device 401 by the first reflection component 307, and the digital micromirror device 401 diffracts the initial uniform pulse laser into multiple beams of parallel light propagating in different directions, and the parallel light is introduced into the 4f optical system 402, 404 when the micromirror of the DMD is in the "on" state, and the parallel light is converted into stripe light by the 4f optical system 402, 404 and the filter 403, and presents a two-dimensional distribution of alternating bright and dark stripes on the output plane. The filter 403 filters out the high-order diffraction light, and the remaining 0th-order and ±1st-order light passes through the second lens 404, the first focusing lens 11 and the third reflector 12 in sequence, and then is reflected by the dichroic mirror 13 into the lens of the objective lens 10, and finally forms stripe light illumination on the plane where the NV color center thin layer of the diamond 101 is located. The final stripe excitation light illumination range is greater than 200 microns, and the stripe contrast is greater than 40%.

[0198] According to some embodiments of the present disclosure, the stripe light is a stripe pulse laser, and the NV color center in the diamond 101 absorbs the stripe light and emits a stripe fluorescence. The stripe fluorescence is collected by the objective lens 10, transmitted through the dichroic mirror 13 into the imaging lens 501, and then passes through the multi-stage filter 502, and finally is collected on the target surface of the fluorescence detector 503.

[0199] According to some optional embodiments of the present disclosure, the first lens 402 is a Fourier lens; the dichroic mirror 13 is a 600 nanometer long-wave pass dichroic mirror; the multi-stage filter 502 is a 900 nanometer short-pass filter. The first reflective component 307 includes two reflectors, a first reflector 3071 and a second reflector 3072, or the first reflective component 307 includes one reflector; and the filter 403 is a low-pass filter.

[0200] Fig.10 The diagram schematically shows the optical path for generating and collecting stripe fluorescence in a wide-field dynamic magnetic imaging device according to another embodiment of the present disclosure.

[0201] According to some embodiments of the present disclosure, Fig.10 As shown, the laser 301 generates an initial continuous laser, the first half-wave plate 302 adjusts the polarization direction of the initial continuous laser to obtain the first continuous laser, the first continuous laser is modulated by the acousto-optic modulator group 303 to output the initial pulse laser, the lens group 304 adjusts the beam diameter of the initial pulse laser, and the initial pulse laser after the beam diameter is adjusted is converted into an initial uniform pulse laser with uniform light intensity distribution by the beam shaper 305; the second half-wave plate 306 adjusts the polarization direction of the initial uniform pulse laser; the initial uniform pulse laser after the polarization direction is changed is reflected by the first reflection component 307 in sequence, and then focused by the first focusing lens 11 to output a focused pulse laser, the focused pulse laser is reflected by the dichroic mirror 13 into the lens of the objective lens 10, focused on the pupil plane of the lens of the objective lens 10, and then passes through the objective lens and is emitted as parallel light, and finally forms uniform excitation light illumination on the plane where the diamond NV color center thin layer 12 is located. The uniform excitation light illumination range finally formed is greater than 200 microns, and the uniformity within the 200 micron range is greater than 90%.

[0202] According to some embodiments of the present disclosure, the NV color center in the diamond 101 absorbs uniform excitation light to generate fluorescence, and the emitted fluorescence is collected by the objective lens 10, passes through the dichroic mirror 13, enters the achromatic lens 14, and then passes through the third reflector 12 to adjust the direction of light and then enter the digital micromirror device 401 at a suitable angle. The digital micromirror device 401 is in the focal plane of the first lens 402, and a pattern is loaded to perform structured light modulation on the wide-field fluorescence distribution of the NV color center. The micromirror in the "on" state of the DMD introduces the outgoing light into the first lens 402, and a filter 403 is placed on the focal plane of the first lens 402 to filter out the high-order diffraction light. The remaining 0th order and ±1st order light passes through the second lens 404 to output stripe fluorescence, which is combined by the imaging lens 501 and the multi-stage filter 502 and finally collected on the target surface of the fluorescence detector 503.

[0203] According to some embodiments of the present disclosure, the objective lens 10 and the imaging lens 501 are combined to form a conjugate plane between the NV color center thin layer plane of the diamond 101 and the fluorescence detection / 503 target surface, and the counts accumulated by each fluorescence detection unit on the target surface of the fluorescence detector 503 are converted into the planar distribution of NV color center fluorescence.

[0204] According to some optional embodiments of the present disclosure, the first lens 402 is an achromatic Fourier lens; the imaging lens 501 is an achromatic imaging lens; the dichroic mirror 13 is a 600-nanometer long-wave pass dichroic mirror; the multi-stage filter 502 is a 900-nanometer short-pass filter; and the first reflective component 307 includes a reflector.

[0205] According to some embodiments of the present disclosure, a Fourier lens can transform an incident light wave into a linear combination of monochromatic plane waves of different frequencies, and this process corresponds to the Fourier transform in mathematics; an achromatic Fourier lens has the ability to eliminate or reduce chromatic aberration while maintaining the basic functions of a Fourier lens; an achromatic imaging lens is an optical element specifically used for imaging, and its main function is to improve imaging quality by eliminating or reducing chromatic aberration.

[0206] According to some embodiments of the present disclosure, by setting the first lens 402 as an achromatic Fourier lens and the imaging lens 501 as an achromatic imaging lens, the chromatic aberration of the collected stripe fluorescence is reduced and the imaging quality of the stripe fluorescence is improved.

[0207] Fig.11 The working principle diagram of the temperature control component in the wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure is schematically shown.

[0208] According to some embodiments of the present disclosure, Fig.11 As shown, the wide field dynamic magnetic imaging device further includes a temperature control component 9, including: a temperature monitor 901, a temperature control box 902 and a temperature controller 903. The temperature monitor 901 is suitable for monitoring the temperature of the surface of the diamond 101; the temperature control box 902 is suitable for placing the probe component 1; and the temperature controller 903 is suitable for controlling the temperature inside the temperature control box 902 to be stable at a target temperature.

[0209] According to some embodiments of the present disclosure, the temperature inside the temperature control box 902 is controlled by setting a temperature control component 9, and then the temperature on the surface of the diamond 101 is controlled, so that the temperature on the surface of the diamond 101 is stabilized at the target temperature, and the stability of the target temperature is guaranteed to be within ±0.01 degrees Celsius. The temperature on the surface of the diamond 101 is controlled to be stable at the target temperature, so that the temperature of the NV color center in the diamond 101 is also controlled to be stable at the target temperature. When the NV color center is in a stable temperature environment, this spin energy level structure can maintain its stability and a long spin coherence time, thereby improving the accuracy of quantum state optical initialization, readout, and quantum state manipulation.

[0210] According to some optional embodiments of the present disclosure, the target temperature is about 30°C.

[0211] Fig.12 The diagram schematically shows the position relationship between the position adjustment component, the probe component, and the sample to be measured in the wide-field dynamic magnetic imaging device according to an embodiment of the present disclosure.

[0212] According to some embodiments of the present disclosure, the wide-field dynamic magnetic imaging device further includes a position adjustment component 15, which includes a Z-axis position adjustment device 151, a two-axis position adjustment device 152, and a three-axis position adjustment device 153. The Z-axis position adjustment device 151 is suitable for adjusting the position of the objective lens 10; the two-axis position adjustment device 152 is suitable for adjusting the position of the probe assembly 1; and the three-axis position adjustment device 153 is suitable for adjusting the position of the sample to be measured 7. The distance between the probe assembly 1 and the sample to be measured 7 is adjusted by adjusting the two-axis position adjustment device 152 and the three-axis position adjustment device 153.

[0213] According to some embodiments of the present disclosure, Fig.12 As shown, the probe assembly 1 is mounted on a two-axis position adjustment device 152, and the probe assembly 1 is located between the objective lens 10 and the sample 7 to be tested. The two-axis position adjustment device 152 can adjust the position of the probe assembly 1 in the X-axis direction and the Y-axis direction, that is, the position of the probe assembly 1 in the xy plane. The objective lens 10 is mounted on a Z-axis position adjustment device 151, and the Z-axis position adjustment device 151 controls the objective lens 10 to focus on the NV color center plane to achieve wide-field fluorescence imaging and readout of the NV color center. The sample 7 to be tested is mounted on a three-axis position adjustment device 153, and the three-axis position adjustment device 153 can adjust the position of the sample 7 to be tested and the substrate 8 in the three directions of the X-axis, Y-axis and Z-axis.

[0214] According to some embodiments of the present disclosure, the three-axis position adjustment device 153 includes a three-axis large-range position adjustment device 1531 and a three-axis small-range position adjustment device 1532. The single-axis stroke of the three-axis small-range position adjustment device 1532 is on the order of hundreds of microns, and the resolution (adjustment accuracy) is 1 nanometer; the single-axis stroke of the Z-axis position adjustment device 151, the two-axis position adjustment device 152 and the three-axis large-range position adjustment device 1531 is on the order of tens of millimeters, and the resolution (adjustment accuracy) is 10 microns. The adjustment accuracy of the three-axis small-range position adjustment device 1532 is greater than the adjustment accuracy of the three-axis large-range position adjustment device 1531. The three-axis large-range position adjustment device 1531 enables the sample 7 and the substrate 8 to be moved over a large range; the three-axis small-range position adjustment device 1532 performs nanometer-level spatial positioning through a nano-piezoelectric displacement stage, which improves the accuracy of spatial position adjustment of the sample 7 and the substrate 8 to be tested.

[0215] According to some embodiments of the present disclosure, the process of experimental measurement by the wide-field dynamic magnetic imaging device is as follows: first, install the diamond 101 containing the NV color center and the sample 7 to be tested; then adjust the sample positions of the diamond 101 containing the NV color center and the sample 7 to be tested so that the NV color center plane moves to the focal plane of the objective lens 10; adjust the external magnetic field so that the direction of the magnetic field coincides with the direction of the NV axis; then perform coherence time measurement to find the NV color center whose properties meet the experimental requirements. After determining the test area, perform experimental data acquisition. Before completing all experiments, each time the time-resolved k-space encoding data acquisition is completed, the NV color center position calibration is performed, and the experiment is continued after the calibration is completed. Repeat the above experimental process until the end of the experiment, and use the data processing component 6 to process the data.

[0216] According to some embodiments of the present disclosure, the data processing component 6 includes a computer workstation of a GPU computing unit. The image reconstruction process in the data processing includes: firstly performing Fourier transform on the real-space images superimposed at each time, resolving the spectrum information of the image collected at each time point in the k-space, moving each spectrum to the origin of the k-space respectively, then applying the filter 403 to sort the signal, and finally reconstructing the real-space image at each time point through inverse Fourier transform to complete the image reconstruction.

[0217] According to some embodiments of the present disclosure, during the specific experimental measurement of the wide-field dynamic magnetic imaging device, the square wave sequence generator is controlled by a computer as a clock source to perform time synchronization control on each component in the system. After the experiment starts, the square wave sequence generator emits a square wave pulse and controls the following components in the system at the same time: controls the acousto-optic modulator group 303 in the laser modulation component 3 to control the laser switch; controls the digital micromirror device 401 in the stripe light modulation component 4 to switch the stripe patterns in different directions; controls the fluorescence detector 503 in the fluorescence detection component 5 to collect fluorescence; controls the microwave switch 203 in the microwave magnetic field component 2 to manipulate the output microwave field. The acousto-optic modulator group 303, the digital micromirror device 401, the fluorescence detector 503 and the microwave switch 203 are combined in a certain time sequence to collect the corresponding fluorescence signal, thereby realizing the high time resolution k-space encoding experimental data collection based on stripe light modulation.

[0218] According to some embodiments of the present disclosure, the magnetic field information is encoded in the quantum state of the NV color center by combining pulsed laser, microwave field, magnetic field and pulse sequence, and the quantum state fluorescence signal is read out by laser pulse.

[0219] Fig.13 The flowchart of the wide-field dynamic magnetic imaging method according to an embodiment of the present disclosure is schematically shown.

[0220] Another aspect of the present disclosure provides a wide-field dynamic magnetic imaging method, using the wide-field dynamic magnetic imaging device, such as Fig.13 As shown, the wide-field dynamic magnetic imaging method includes operations S101 to S105.

[0221] In operation S101 , the laser modulation component 3 is used to output an initial uniform pulse laser to excite the diamond 101 containing NV color centers to emit fluorescence, and the fluorescence includes magnetic field information of the sample 7 to be tested.

[0222] In operation S102 , the stripe light modulation component 4 is used to modulate the initial uniform pulse laser to output stripe pulse laser, so that the fluorescence emitted by the diamond 101 is stripe fluorescence; or the fluorescence emitted by the diamond 101 is modulated into stripe fluorescence.

[0223] In operation S103 , the microwave magnetic field assembly 2 is used to generate a uniform microwave field and a uniform bias magnetic field at the position of the diamond 101 to control the spin energy level and quantum state evolution process of the diamond 101 .

[0224] In operation S104 , the stripe fluorescence is spatially imaged using the fluorescence detection component 5 to obtain the magnetic field information of the sample to be tested 7 , and then obtain an initial magnetic image of the sample to be tested 7 .

[0225] In operation S105 , the initial magnetic image is subjected to Fourier transform and inverse Fourier transform processing by the data processing component 6 to obtain a first magnetic image.

[0226] According to some embodiments of the present disclosure, the initial magnetic image includes a two-dimensional real-space image obtained by superimposing sub-two-dimensional real-space images obtained at multiple moments, and the first magnetic image includes multiple sub-two-dimensional real-space images corresponding to the multiple moments respectively.

[0227] According to some embodiments of the present disclosure, the laser modulation component 3 is used to output an initial uniform pulse laser to excite the diamond 101 containing the NV color center to emit fluorescence, and the fluorescence includes the magnetic field information of the sample 7 to be tested; the stripe light modulation component 4 is used to modulate the initial uniform pulse laser to output a stripe pulse laser, so that the fluorescence emitted by the diamond 101 is stripe fluorescence; or the fluorescence emitted by the diamond 101 is modulated to stripe fluorescence; the microwave magnetic field component 2 is used to generate a uniform microwave field and a uniform bias magnetic field at the position of the diamond 101 to regulate the spin energy level and quantum state evolution process of the diamond 101; the fluorescence detection component 5 is used to perform spatial imaging of the stripe fluorescence to obtain the magnetic field information of the sample 7 to be tested, and then obtain the initial magnetic image of the sample 7 to be tested; the initial magnetic image is Fourier transformed and inverse Fourier transformed by the data processing component 6 to obtain a first magnetic image; and sub-millisecond to microsecond time-resolved measurement of high-frequency dynamic signals under the requirement of high spatial resolution is achieved.

[0228] Fig.14 The flowchart schematically shows a method for wide-field dynamic magnetic imaging according to an embodiment of the present disclosure, which uses a data processing component to perform Fourier transform and inverse Fourier transform on an initial magnetic image to obtain a first magnetic image.

[0229] According to some embodiments of the present disclosure, Fig.14 As shown, the initial magnetic image is subjected to Fourier transform and inverse Fourier transform processing by using the data processing component 6 to obtain the first magnetic image, including operations S201 to S203.

[0230] In operation S201 , Fourier transform processing is performed on the initial magnetic image to obtain a frequency domain signal, and the frequency domain signal is represented in the form of a two-dimensional k-space image.

[0231] In operation S202 , image frequency domain signals at different moments are acquired according to the two-dimensional k-space image.

[0232] In operation S203, an inverse Fourier transform is performed on the image frequency domain signal to obtain a first magnetic image.

[0233] According to some embodiments of the present disclosure, in operation S202, based on the two-dimensional k-space image, the image frequency domain signals at different times in the two-dimensional k-space image are separated, and a k-space filter is constructed for each image at each time, and its center position is , with a width of W, which satisfies , that is, the filter width is less than or equal to the spatial frequency difference between the two fringes with the closest period and direction, so as to ensure that the separated signal will not be interfered by fringes in other directions; after applying the k-space filter to all cosine fringes, M two-dimensional k-space frequency domain signals are obtained, representing the frequency domain signals at different times, that is, the image frequency domain signals at different times are obtained.

[0234] According to some embodiments of the present disclosure, in operation S203, for the image frequency domain signals obtained at different times, the zero frequency position of the two-dimensional frequency domain signal corresponding to each stripe is changed from Move to the origin of the two-dimensional k-space, and then perform inverse Fourier transform to obtain the real-space image of each fringe code, that is, the two-dimensional real-space magnetic field map at the corresponding moment, that is, the first magnetic image including multiple sub-two-dimensional real-space images corresponding to multiple moments.

[0235] According to some embodiments of the present disclosure, k-space is an abstract space (three-dimensional space or two-dimensional plane) in which data points represent the spatial frequency information of an image. The spatial frequency k is described by three components Kx, Ky, and Kz, which correspond to a three-dimensional frequency space. In a two-dimensional image, we usually only focus on two components, Kx and Ky. Each point in the k-space corresponds to a combination of a series of sine waves of different frequencies, phases, and directions in the image. Therefore, the data in the k-space can be regarded as a representation of the image in the frequency domain. When we acquire an image, the image is actually a two-dimensional matrix composed of a series of pixel values. These pixel values ​​represent the brightness or grayscale information of the image in the spatial domain. In order to analyze the frequency content of the image, we can perform a two-dimensional Fourier transform on the image. This process converts the pixel values ​​of the image into frequency coefficients in complex form, which describe the size and phase of different frequency components in the image. The result of the transformation is a two-dimensional k-space image. In a k-space image, low-frequency components (corresponding to large-scale structures in the image) are usually located in the central area, while high-frequency components (corresponding to edges and details in the image) are distributed in the edge area. By analyzing k-space images, we can better understand the frequency distribution and characteristics of images. At the same time, we can also use k-space data to optimize the image reconstruction process and improve the image resolution and contrast.

[0236] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations and / or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways without departing from the spirit and teachings of the present disclosure. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0237] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A wide-field dynamic magnetic imaging device, wherein: include: A probe assembly including a diamond containing NV color centers; A microwave magnetic field assembly, adapted to generate a uniform microwave field and a uniform bias magnetic field near the diamond, so as to regulate the spin energy level and quantum state evolution process of the diamond; A laser modulation component, adapted to output an initial uniform pulse laser to excite the diamond to emit fluorescence, wherein the fluorescence includes magnetic field information of the sample to be tested; A stripe light modulation component is used to modulate the initial uniform pulse laser to output a stripe pulse laser, so that the fluorescence emitted by the diamond is stripe fluorescence; or directly modulate the fluorescence emitted by the diamond into stripe fluorescence; A fluorescence detection component, adapted to perform spatial imaging of the stripe fluorescence to obtain magnetic field information of the sample to be tested, and further obtain an initial magnetic image of the sample to be tested; as well as a data processing component adapted to perform Fourier transform and inverse Fourier transform processing on the initial magnetic image to obtain a first magnetic image; The initial magnetic image includes a two-dimensional real space image obtained by superimposing sub-two-dimensional real space images obtained at multiple moments, and the first magnetic image includes multiple sub-two-dimensional real space images corresponding to the multiple moments respectively.

2. The wide-field dynamic magnetic imaging device according to claim 1, wherein: The surface of the diamond containing NV color centers is flat, and contains a plurality of NV color centers, and the plurality of NV color centers form a thin layer inside the diamond; The depth difference between two adjacent NV color centers is less than 10 microns, and the distance between two adjacent NV color centers in the horizontal direction is less than the optical diffraction limit.

3. The wide-field dynamic magnetic imaging device according to claim 2, wherein: The laser modulation assembly comprises: A laser, suitable for outputting an initial continuous laser; A first half-wave plate, adapted to adjust the polarization direction of the initial continuous laser to obtain a first continuous laser; an acousto-optic modulator group, adapted to modulate the first continuous laser to obtain an initial pulse laser, so as to improve an on / off ratio of the initial pulse laser; A lens group, adapted to adjust the beam diameter of the initial pulse laser; and The beam shaper is adapted to convert the beam of the initial pulsed laser into a flat-top beam with uniform light intensity distribution, so as to output the initial uniform pulsed laser.

4. The wide-field dynamic magnetic imaging device according to claim 3, wherein: The stripe light modulation component comprises: A digital micromirror device, adapted to diffract the initial uniform pulsed laser into multiple beams of parallel light propagating in different directions; A 4f optical system, adapted to convert the plurality of parallel light beams into striped light, wherein the striped light presents a two-dimensional distribution of alternating bright and dark stripes on an output plane; and A filter is arranged in the 4f optical system, and the filter is suitable for filtering out stray light in the multiple beams of parallel light.

5. The wide-field dynamic magnetic imaging device according to any one of claims 1 to 4, wherein: The fluorescence detection assembly comprises: an imaging lens adapted to focus the fluorescence to form a fluorescence image; A multi-stage filter, adapted to filter out stray light signals and laser light reflected from the diamond surface; and The fluorescence detector is adapted to convert the fluorescence signal into an electrical signal so as to obtain the magnetic field information of the sample to be tested.

6. The wide-field dynamic magnetic imaging device according to claim 5, wherein: The probe assembly also includes: A uniform radiation structure is suitable for providing a microwave field to change the spin quantum state of the NV color center in the diamond.

7. The wide-field dynamic magnetic imaging device according to claim 6, wherein: The microwave magnetic field assembly comprises: A microwave source, suitable for generating initial microwaves of a specific frequency and power; A microwave beam splitter, adapted to split the initial microwave into two first microwaves with equal power and a phase difference of 90°; A microwave switch, adapted to control the on and off of two transmission paths of the first microwave; A microwave combiner, adapted to combine two of the first microwaves into one second microwave; A microwave amplifier, adapted to amplify the power of the second microwave to obtain a third microwave, wherein the third microwave enters the uniform radiation structure; an isolator, adapted to prevent the third microwave from being reflected and entering the microwave amplifier; Impedance matching, suitable for reducing the loss during the third microwave transmission process; and A magnetic field source is suitable for providing a uniform bias magnetic field.

8. The wide-field dynamic magnetic imaging device according to claim 7, wherein: Also included are temperature control components, including: a temperature monitor adapted to monitor the temperature of the diamond surface, a temperature control box, suitable for housing the probe assembly; and The temperature controller is adapted to control the temperature inside the temperature control box to be stable at a target temperature.

9. A wide-field dynamic magnetic imaging method, using the wide-field dynamic magnetic imaging device according to any one of claims 1 to 8, wherein: The method comprises: Using a laser modulation component to output an initial uniform pulse laser to excite the diamond containing the NV color center to emit fluorescence, wherein the fluorescence includes magnetic field information of the sample to be tested; The initial uniform pulse laser is modulated by a stripe light modulation component to output a stripe pulse laser, so that the fluorescence emitted by the diamond is stripe fluorescence; or the fluorescence emitted by the diamond is modulated into stripe fluorescence; Using a microwave magnetic field assembly to generate a uniform microwave field and a uniform bias magnetic field at the position of the diamond to regulate the spin energy level and quantum state evolution process of the diamond; Using a fluorescence detection component to perform spatial imaging on the stripe fluorescence to obtain magnetic field information of the sample to be tested, and then obtain an initial magnetic image of the sample to be tested; Using a data processing component to perform Fourier transform and inverse Fourier transform on the initial magnetic image to obtain a first magnetic image; The initial magnetic image includes a two-dimensional real space image obtained by superimposing sub-two-dimensional real space images obtained at multiple moments, and the first magnetic image includes multiple sub-two-dimensional real space images corresponding to the multiple moments respectively.

10. The wide-field dynamic magnetic imaging method according to claim 9, wherein: The using a data processing component to perform Fourier transform and inverse Fourier transform on the initial magnetic image to obtain a first magnetic image comprises: Performing Fourier transform processing on the initial magnetic image to obtain a frequency domain signal, wherein the frequency domain signal is represented in the form of a two-dimensional k-space image; Acquiring image frequency domain signals at different times according to the two-dimensional k-space image; Perform an inverse Fourier transform on the image frequency domain signal to obtain a first magnetic image.

Images