NV color center measurement sensitivity improving device based on long focal depth Bessel beam

Abstract

The invention discloses an NV color center measurement sensitivity improving device based on a long focal depth Bessel beam, which relates to the field of quantum sensing and optical detection magnetic resonance measurement and comprises a laser modulation system, a fluorescence excitation and acquisition system and a data processing system. The laser modulation system comprises a laser capable of emitting continuous laser and a modulation module used for modulating light beams. Wherein the modulation module comprises an acousto-optic modulator used for modulating the continuous laser into a horizontal polarization pulse laser beam, and a spatial light modulator used for modulating the horizontal polarization pulse laser beam into a long-focal-depth Bessel beam. By arranging the spatial light modulator, an excitation light beam is converted into a long-focal-depth Bessel light beam, the transmission distance of the long-focal-depth Bessel light beam is prolonged in a phase modulation mode, the extension of the transmission distance enables the excitation light beam to deeply pump diamond and excite more diamond NV color centers to participate in spin polarization, and the sensitivity of sensing measurement is improved.

Description

Technical Field

[0001] The present invention relates to the field of quantum sensing and optical detection magnetic resonance measurement, and in particular to a device for improving the sensitivity of NV color center measurement based on a long-focus deep Bessel beam. Background Art

[0002] Nitrogen-vacancy (NV) color centers have attracted much attention in recent years due to their unique advantages in quantum computing, quantum sensing, and magnetic resonance imaging. The spin state of the NV color center can be polarized by optical pumping, and its quantum state can be detected using optically detected magnetic resonance (ODMR) technology, thereby achieving highly sensitive measurements of physical quantities such as weak magnetic fields and temperature changes.

[0003] However, conventional optical pumping techniques usually use Gaussian light fields to excite NV centers. Although this method can achieve spin polarization to a certain extent, the energy of the Gaussian light field diffuses rapidly during transmission, resulting in insufficient pumping depth, which leads to failure to fully excite deeper NV centers, limiting its application in high-sensitivity sensors. When the Gaussian light field is focused on the diamond surface through a high-power objective lens, its energy diffuses rapidly along the transmission direction, making it difficult to maintain sufficient light intensity to effectively pump deep NV centers in the diamond material. This lack of pumping depth directly affects the number of electrons involved in spin polarization, thereby limiting the overall sensitivity and signal contrast of the NV center system. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] The present invention aims to solve the problem of low measurement sensitivity in existing diamond NV color center measurement devices due to insufficient pumping depth of the excitation beam.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: a device for improving the measurement sensitivity of NV color center based on a long-focus-depth Bessel beam, comprising a laser modulation system, a fluorescence excitation and acquisition system and a data processing system; the laser modulation system comprises a laser capable of emitting continuous laser light, and a modulation module for modulating the light beam; wherein the modulation module comprises an acousto-optic modulator for modulating the continuous laser light into a horizontally polarized pulsed laser beam, and a spatial light modulator for modulating the horizontally polarized pulsed laser beam into a long-focus-depth Bessel beam; the fluorescence excitation and acquisition system comprises a fluorescence excitation module and a fluorescence acquisition module; wherein the fluorescence excitation module comprises an objective lens, and a diamond NV color center arranged on the end face of the objective lens, the diamond NV color center is used to focus the long-focus-depth Bessel beam, and the objective lens is used to collect the fluorescence generated by the diamond NV color center after stimulated radiation; the fluorescence acquisition module comprises an avalanche photodiode for converging fluorescence; and the avalanche photodiode is electrically connected to the data processing system.

[0007] As a preferred solution of the NV color center measurement sensitivity improvement device based on the long-focus deep Bessel beam described in the present invention, a Green-Taylor prism is provided at the front end of the acousto-optic modulator, and a first aperture is provided at the rear end of the acousto-optic modulator. After being emitted through the output end of the laser, the continuous laser passes through the Green-Taylor prism, the acousto-optic modulator and the first aperture in sequence.

[0008] As a preferred solution of the NV color center measurement sensitivity improvement device based on a long-focal-depth Bessel beam described in the present invention, the modulation module also includes a first reflector and a beam expansion and collimation unit which are arranged between the acousto-optic modulator and the spatial light modulator and are arranged in sequence along the propagation direction of the horizontally polarized pulse laser beam; the beam expansion and collimation unit includes a first lens and a second lens of increased size. After the horizontally polarized pulse laser beam is reflected by the first reflector, it is guided to pass through the first lens and the second lens in sequence for shaping, and then enters the phase-loaded spatial light modulator to be modulated into a long-focal-depth Bessel beam.

[0009] As a preferred solution of the NV color center measurement sensitivity enhancement device based on long-focus deep Bessel beam described in the present invention, the spatial light modulator is a phase-type spatial light modulator, which modulates the amplitude, phase and polarization state of the light beam by loading a phase grayscale image.

[0010] As a preferred solution of the NV color center measurement sensitivity enhancement device based on the long focal depth Bessel beam of the present invention, the phase value calculation formula loaded on the spatial light modulator is:

[0011] T=T bessl *T op ;

[0012] T bessl =exp{i*sgn[Jn (2πr0ρ)]};

[0013]

[0014] Where T is the phase value loaded on the spatial light modulator, T bessl is the phase function of the Bessel beam, T op is the phase distribution function used to optimize the transmission characteristics; J n =1 represents the first-order Bessel, r0=5 is the number of Bessel beam diffraction rings, ρ is the coordinate information of the incident beam in cylindrical coordinates; N is the number of beams, x j ,y j and z j is the position of the jth beam in the focal plane.

[0015] As a preferred solution of the NV color center measurement sensitivity improvement device based on long focal depth Bessel beam described in the present invention, wherein: the laser modulation system also includes a spatial filter arranged at the rear end of the spatial light modulator, the spatial filter includes a second aperture, a third lens, and a fourth lens, the third lens and the fourth lens have the same structure and are symmetrically arranged on both sides of the second aperture.

[0016] As a preferred solution of the NV color center measurement sensitivity improvement device based on the long-focus depth Bessel beam described in the present invention, the fluorescence excitation module also includes a dichroic mirror that receives and guides the long-focus depth Bessel beam to enter the objective lens. After the long-focus depth Bessel beam is emitted from the spatial light modulator, it passes through the spatial filter and is incident on the dichroic mirror.

[0017] As a preferred solution of the NV color center measurement sensitivity enhancement device based on long-focus deep Bessel beam described in the present invention, the fluorescence excitation module also includes a microwave antenna for manipulating the electron spin state of the diamond NV color center.

[0018] As a preferred solution of the NV color center measurement sensitivity improvement device based on long-focus deep Bessel beam described in the present invention, the fluorescence collection module also includes a third reflector arranged at the rear end of the dichroic mirror, and a filter and a focusing lens arranged between the third reflector and the avalanche photodiode and arranged in sequence along the fluorescence propagation direction.

[0019] As a preferred solution of the NV color center measurement sensitivity enhancement device based on long focal depth Bessel beam described in the present invention, the laser is selected from one of semiconductor laser, gas laser, solid-state laser and laser diode, and its wavelength range is 500nm~637nm.

[0020] The beneficial effects of the present invention are as follows: by setting a spatial light modulator, the excitation light beam is converted into a long-focus deep Bessel light beam, and the long-focus deep Bessel light beam extends the light beam transmission distance by phase modulation. The extension of the transmission distance enables the excitation light beam to deeply pump the diamond, stimulate more diamond NV color centers to participate in spin polarization, and improve the sensitivity of the sensor measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0023] Figure 2 This is the transmission characteristic diagram of Gaussian beam.

[0024] Figure 3 Schematic diagram of Gaussian beam pumping NV color center.

[0025] Figure 4 This is the transmission characteristic diagram of the long-focus deep Bessel beam.

[0026] Figure 5 Schematic diagram of long-focus deep Bessel beam pumping NV color center.

[0027] In the figure: 10, laser modulation system; 101, laser; 102, Green Taylor prism; 103, acousto-optic modulator; 104, first aperture; 105, first reflector; 106, first lens; 107, second lens; 108, spatial light modulator; 109, third lens; 110, second aperture; 111, fourth lens; 20, fluorescence excitation and collection system; fluorescence excitation module; fluorescence collection module; 201, dichroic mirror; 202, objective lens; 203, microwave antenna; 204, diamond NV color center; 205, third reflector; 206, filter; 207, focusing lens; 208, avalanche photodiode; 30, data processing system. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0030] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0031] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0032] Example 1

[0033] Reference Figure 1 , which is the first embodiment of the present invention, provides a device for improving the sensitivity of NV color center measurement based on a long-focus deep Bessel beam, including a laser modulation system 10, a fluorescence excitation and collection system 20 and a data processing system 30.

[0034] Furthermore, the laser modulation system 10 can emit a laser 101 for continuous laser light, and a modulation module for modulating the laser beam, wherein the modulation module includes a Green Taylor prism 102, an acousto-optic modulator 103, and a first aperture 104 arranged in sequence along the emission direction of the continuous laser light. The continuous laser light is emitted through the output end of the laser 101, and then sequentially passes through the Green Taylor prism 102, the acousto-optic modulator 103, and the first aperture 104, and is modulated into a horizontally polarized pulse laser beam. The horizontally polarized pulse laser beam is a type of Gaussian beam.

[0035] Specifically, the acousto-optic modulator 103 and the first aperture 104 are used as modulation means to control the intensity change of the continuous laser beam. The acousto-optic modulator 103 converts the continuous laser into a multi-level pulse laser, and the first aperture 104 selects the first-order diffracted light as the incident light.

[0036] Furthermore, the modulation module also includes a beam expansion and collimation unit and a spatial light modulator 108 arranged at the rear end of the acousto-optic modulator; wherein the beam expansion and collimation unit includes a first lens 106 and a second lens 107 of increased size, and after being reflected by the first reflector 105, the horizontally polarized pulsed laser beam is guided to pass through the first lens 106 and the second lens 107 in sequence for shaping, and then enters the phase-loaded spatial light modulator 108, and is modulated into a long-focus depth Bessel beam. A long-focus depth Bessel beam is a type of Bessel beam. The phase distribution loaded on the spatial light modulator 108 has two major functions: one is to modulate the input Gaussian beam into a Bessel beam; the other is to further extend the transmission distance of the beam to achieve the generation of a long-focus depth Bessel beam.

[0037] The calculation formula of the phase value loaded on the spatial light modulator 108 is:

[0038] T=T bessl *T op

[0039] Where, T bessl is the phase function of the Bessel beam, T op is the phase distribution function used to optimize the transmission characteristics.

[0040] Furthermore, T bessl is the phase function of the Bessel beam, which is expressed as:

[0041] T bessl =exp{i*sgn[J n (2πr0ρ)]}

[0042] In the formula, J n =1 represents the first-order Bessel, r0=5 is the number of Bessel beam diffraction rings, and ρ is the coordinate information of the incident light beam in cylindrical coordinates.

[0043] Furthermore, T op It is a phase function used to optimize the transmission characteristics, which can realize the control of the number and position of focal spots. Its expression is:

[0044]

[0045] Where N is the number of beams, x j ,y j and z jis the position of the jth beam in the focal plane. For example, when (x1, y1, z1) = (0, 0, 0) and (x2, y2, z2) = (0, 0, 1), they represent the position information of the first and second Bessel beams, respectively. Through this spatial configuration, the optimization of energy transfer is achieved: when the energy of the first Bessel beam dissipates rapidly during transmission, the second beam can continue the energy in time, thereby extending the transmission distance of the entire beam. The number of beams is not limited to two, and can be a multi-focal arrangement. This method effectively enhances the transmission stability of the Bessel beam, overcomes the problem of rapid energy attenuation caused by the diffraction of a single beam, and realizes the generation of a long-focus deep Bessel beam.

[0046] Furthermore, the laser modulation system 10 also includes a spatial filter arranged at the rear end of the spatial light modulator 108, and the spatial filter includes a second aperture 110, a third lens 109, and a fourth lens 111. The third lens 109 and the fourth lens 111 have the same structure and are symmetrically arranged on both sides of the second aperture 110; after being emitted from the spatial light modulator 108, the long focal depth Bessel light beam passes through the spatial filter and is incident on the fluorescence excitation and collection system 20.

[0047] Specifically, the laser 101 is selected from one of semiconductor laser, gas laser, solid-state laser and laser diode, and its wavelength range is 500nm~637nm.

[0048] Specifically, the material used for the Green Taylor prism 102 is rhombic hexahedral crystal of CaCO3.

[0049] Specifically, the material of the first lens 106 and the second lens 107 is one of optical glass, ultraviolet fused quartz, calcium fluoride, germanium, silicon, and zinc selenide.

[0050] Specifically, the spatial light modulator 108 is a phase-type spatial light modulator, which modulates the amplitude, phase and polarization state of the light beam by loading a phase grayscale image.

[0051] In summary, if Figure 2 and Figure 3 As shown, after the Gaussian beam is focused onto the diamond surface by the objective lens 202, the energy is difficult to maintain and diffuses rapidly, resulting in a decrease in the polarization of the diamond NV color center 204, which limits the sensitivity improvement of the sensing measurement. The present device uses a spatial light modulator 108 to modulate the excitation beam into a long-focus deep Bessel beam. In contrast, the long-focus deep Bessel beam extends the beam transmission distance by phase modulation, effectively solving the problem of low polarization rate caused by insufficient pumping distance of the excitation beam.

[0052] Secondly, the sensitivity of the sensing measurement is mainly limited by the electron spin density of the diamond NV color center 204 involved in the laser polarization. This device modulates the excitation beam into a long-focus deep Bessel beam, and the energy of the long-focus deep Bessel beam can be maintained for a certain distance during the transmission process, thereby achieving deep pumping of diamond, such as Figure 4 and Figure 5 This pumping method effectively excites more diamond NV color centers 204 for spin polarization, thereby significantly improving the sensitivity of sensing measurements.

[0053] Example 2

[0054] Reference Figure 1 , which is the second embodiment of the present invention. This embodiment is different from the first embodiment in that: the beam guiding module includes a first reflector 105 arranged between the first lens 106 and the aperture 104, and the first reflector 105 is used to reflect the horizontally polarized pulse laser beam and guide the horizontally polarized pulse laser beam into the phase-loaded spatial light modulator 108.

[0055] Specifically, the first reflector 105 is selected from a metal reflector, a dielectric reflector or an anti-reflection reflector.

[0056] In summary, by setting the first reflector 105, the optical reflection principle is used to guide the deflection direction of the light beam. When in use, the first reflector 105 is freely adjusted to change the incident angle of the light beam, so as to achieve the purpose of adjusting the exit direction and ensure that the light beam is correctly guided to the next component (i.e., the first lens 106). At the same time, by setting the first reflector 105, the light beam is reflected and the direction is changed, and the light beam no longer propagates along a straight line, so that the device can be built in a three-dimensional space, so that the device as a whole is not too long.

[0057] The remaining structures are the same as those of Example 1.

[0058] Example 3

[0059] Reference Figure 1, which is the third embodiment of the present invention, and this embodiment is different from the second embodiment in that: the fluorescence excitation and collection system 20 includes a fluorescence excitation module and a fluorescence collection module. The fluorescence excitation module includes a dichroic mirror 201, an objective lens 202, a microwave antenna 203, and a diamond NV color center 204, wherein the diamond NV color center 204 is arranged on the end face of the objective lens 202, and the long focal depth Bessel beam is emitted from the spatial light modulator 108, passes through the spatial filter, and is incident on the dichroic mirror 201, and the dichroic mirror 201 is used to receive and guide the long focal depth Bessel beam into the objective lens 202, and is finally focused on the diamond NV color center 204, and the fluorescence generated by the diamond NV color center 204 after stimulated radiation is collected by the objective lens 202, and the electronic spin state of the diamond NV color center 204 is precisely controlled by the microwave antenna 203.

[0060] Furthermore, the fluorescence collection module includes a second reflector 205, a filter 206, a focusing lens 207, and an avalanche photodiode 208, which are sequentially arranged along the direction of fluorescence propagation. The third reflector 205 is arranged at the rear end of the dichroic mirror 201, and is used to reflect the fluorescence and guide the fluorescence into the filter 206. The fluorescence collected by the objective lens 202 is propagated through the dichroic mirror 201 and the reflector, guided to the filter 206, and then through the focusing lens 207 in a straight line, and then converged to the photosensitive surface of the avalanche photodiode 208 for detection, so as to achieve accurate collection.

[0061] Furthermore, the avalanche photodiode 208 is electrically connected to the data processing system 30 .

[0062] Specifically, the second reflector 205 is selected from a metal reflector, a dielectric reflector or an anti-reflection reflector.

[0063] Specifically, the focusing lens 207 is made of one of optical glass, ultraviolet fused quartz, calcium fluoride, germanium, silicon, and zinc selenide.

[0064] Specifically, the dichroic mirror 201 is one of the series of dichroic mirrors that reflect green and transmit red.

[0065] Specifically, the objective lens 202 has a numerical aperture greater than that of an oil immersion objective lens.

[0066] Specifically, the diamond NV color center 204 is a type of high-concentration NV color center diamond ensemble.

[0067] Specifically, the microwave antenna 203 is a coplanar, planar waveguide antenna.

[0068] Specifically, the filter 206 is a 600 nm high-pass filter.

[0069] Specifically, the avalanche photodiode 208 is one having a central wavelength around 630 nm.

[0070] In summary, when in use, first, the output end of the laser 101 emits a continuous laser, which is modulated into a horizontally polarized pulsed laser beam after passing through the Green Taylor prism 102, the acousto-optic modulator 103 and the aperture 104 in sequence. Then, the beam is guided by the first reflector 105 to the beam expansion and collimation unit composed of the first lens 106 and the second lens 107 for beam shaping, and then enters the phase-loaded spatial light modulator 108 to be modulated into a long-focus depth Bessel beam. Finally, the beam passes through a spatial filter (the long-focus depth Bessel beam passes through the third lens 109, the second aperture 110 and the fourth lens 111 in sequence) and is incident on the dichroic mirror 201, laying the foundation for subsequent fluorescence excitation and signal acquisition.

[0071] Secondly, the long focal depth Bessel beam is reflected by the dichroic mirror 201 to the objective lens 202 and is focused to the diamond NV center 204. During this process, the electronic spin state of the NV center is precisely controlled by the microwave antenna 203. The fluorescence generated by the stimulated radiation of the NV center 204 is first collected by the objective lens 202, then guided to the filter 206 through the dichroic mirror 201 and the second reflector 205, and finally focused by the focusing lens (207) to the photosensitive surface of the avalanche photodiode 208 for detection, so as to achieve accurate collection. The collected fluorescence data is then transmitted to the data processing system 30, where further data processing and analysis are performed to extract and parse relevant information.

[0072] The remaining structure is the same as that of Example 2.

[0073] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0074] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0075] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0076] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A device for improving the sensitivity of NV color center measurement based on a long-focus deep Bessel beam, characterized by: It comprises a laser modulation system (10), a fluorescence excitation and collection system (20) and a data processing system (30); The laser modulation system (10) comprises a laser (101) capable of emitting continuous laser light, and a modulation module for modulating the laser beam; wherein the modulation module comprises an acousto-optic modulator (103) for modulating the continuous laser light into a horizontally polarized pulse laser beam, and a spatial light modulator (108) for modulating the horizontally polarized pulse laser beam into a long-focus depth Bessel beam; The fluorescence excitation and collection system (20) comprises a fluorescence excitation module and a fluorescence collection module; wherein the fluorescence excitation module comprises an objective lens (202) and a diamond NV color center (204) arranged on the end face of the objective lens (202), the diamond NV color center (204) is used to focus a long-focus deep Bessel light beam, and the objective lens (202) is used to collect fluorescence generated by the diamond NV color center (204) after stimulated radiation; the fluorescence collection module comprises an avalanche photodiode (208) for converging fluorescence; The avalanche photodiode (208) is electrically connected to the data processing system (30).

2. The device for improving the NV color center measurement sensitivity based on a long focal depth Bessel beam according to claim 1, characterized in that: The modulation module further comprises a Green Taylor prism (102) arranged at the front end of the acousto-optic modulator (103), and a first aperture (104) arranged at the rear end of the acousto-optic modulator (103); after being emitted through the output end of the laser (101), the continuous laser passes through the Green Taylor prism (102), the acousto-optic modulator (103) and the first aperture (104) in sequence.

3. The device for improving the NV color center measurement sensitivity based on a long focal depth Bessel beam according to claim 2, characterized in that: The modulation module further includes a first reflector (105) and a beam expansion and collimation unit arranged between the acousto-optic modulator (103) and the spatial light modulator (106); The beam expansion and collimation unit comprises a first lens (106) and a second lens (107) of increased size. After being reflected by a first reflector (105), the horizontally polarized pulsed laser beam is guided to sequentially pass through the first lens (106) and the second lens (107) for shaping, and then enters a phase-loaded spatial light modulator (108) to be modulated into a long-focus depth Bessel beam.

4. The device for improving the NV color center measurement sensitivity based on a long focal depth Bessel beam according to claim 3, characterized in that: The spatial light modulator (108) is a phase-type spatial light modulator, which modulates the amplitude, phase and polarization state of the light beam by loading a phase grayscale image.

5. The device for improving the NV color center measurement sensitivity based on a long focal depth Bessel beam according to claim 4, characterized in that: The calculation formula of the phase value loaded on the spatial light modulator (108) is: T=T bessl *T op ; T bessl =exp{i*sgn[J n (2πr0ρ)]}; Where, T is the phase value loaded on the spatial light modulator (108), T bessl is the phase function of the Bessel beam, T op is the phase distribution function used to optimize the transmission characteristics; J n =1 represents the first-order Bessel, r0=5 is the number of Bessel beam diffraction rings, ρ is the coordinate information of the incident beam in cylindrical coordinates; N is the number of beams, x j ,y j and z j is the position of the jth beam in the focal plane.

6. The device for improving the NV color center measurement sensitivity based on a long focal depth Bessel beam according to claim 4 or 5, characterized in that: The laser modulation system (10) further comprises a spatial filter arranged at the rear end of the spatial light modulator (108), the spatial filter comprising a second aperture (110), a third lens (109), and a fourth lens (111), the third lens (109) and the fourth lens (111) having the same structure and being symmetrically arranged on both sides of the second aperture (110).

7. The device for improving the NV color center measurement sensitivity based on a long focal depth Bessel beam according to claim 6, characterized in that: The fluorescence excitation module also includes a dichroic mirror (201) for receiving and guiding the long-focus-depth Bessel light beam to enter the objective lens (202); after the long-focus-depth Bessel light beam is emitted from the spatial light modulator (108), it passes through a spatial filter and is incident on the dichroic mirror (201).

8. The device for improving the NV color center measurement sensitivity based on a long focal depth Bessel beam according to claim 7, characterized in that: The fluorescence excitation module also includes a microwave antenna (203) for manipulating the electron spin state of the diamond NV color center (204).

9. The device for improving the NV color center measurement sensitivity based on a long focal depth Bessel beam according to claim 8, characterized in that: The fluorescence collection module further comprises a second reflector (205) arranged at the rear end of the dichroic mirror (201), and a filter (206) and a focusing lens (207) arranged between the second reflector (205) and the avalanche photodiode (208) and arranged in sequence along the fluorescence propagation direction.

10. The device for improving the NV color center measurement sensitivity based on a long focal depth Bessel beam according to claim 1, or 2, or 3, or 4, or 5, or 7, or 8, or 9, characterized in that: The laser (101) is selected from one of semiconductor lasers, gas lasers, solid-state lasers and laser diodes, and has a wavelength range of 500nm to 637nm.

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