A diamond magnetic field imaging device and method based on a special-shaped light beam

Abstract

This invention provides a diamond magnetic field imaging device and method based on an irregularly shaped beam, belonging to the field of diamond thin-film magnetic imaging technology. It includes a linearly polarized light excitation unit, a scalar irregularly shaped beam modulation unit, a fluorescence collection and detection unit, and a data processing unit. The linearly polarized light excitation unit emits laser light to the scalar irregularly shaped beam modulation unit, generating a scalar irregularly shaped beam. The scalar irregularly shaped beam passes through the fluorescence collection and detection unit to obtain a fluorescence image containing information about the magnetic field to be measured. The data processing unit processes the ODMR spectral data of each pixel according to a frequency sweep applied by microwaves, and then fits the image of the magnetic field to be measured according to the Lorentz relationship. This device utilizes an irregularly shaped beam with adjustable shape and geometric side count generated by cross-phase generation to calibrate the spatial positional relationship between the measured magnetic field image and the sample under test. This method not only eliminates the pre-calibration step required in existing technologies but also improves detection efficiency, eliminating the need to move the magnetic field to be measured.

Description

Technical Field

[0001] This invention relates to a diamond magnetic field imaging device and method based on an irregularly shaped beam, belonging to the field of diamond thin-film magnetic imaging technology. Background Technology

[0002] In recent years, the integration of quantum mechanics with information technology, laser technology, and biotechnology has garnered significant attention in fields such as quantum communication encryption, geological surveying, mineral exploration, military applications, industrial manufacturing, and biomedicine. Besides the relatively mature quantum communication and atomic clock technologies, quantum sensing and measurement technologies utilizing atomic spin effects have also made groundbreaking progress in recent years. Among numerous solid-state atomic spin materials, diamond, containing negatively charged nitrogen-vacancy (NV) color centers, stands out due to its ease of optical polarization and readout. Therefore, using diamond as a quantum sensor for magnetic field imaging is of great significance for the development and application of these fields.

[0003] In the prior art, patent CN 113281683 A discloses a microwave antenna and its fabrication method for a diamond thin-film magnetic imaging device. The diamond thin-film magnetic imaging device uses a laser to emit a 532nm green laser, which is expanded into a parallel beam by a convex lens and then applied to the NV color centers of the diamond thin film by a dichroic filter. The fluorescence generated after the NV color centers of the diamond thin film are excited passes through the dichroic filter and a filter before being collected by a CCD camera. The output signal of the CCD camera serves as the input signal of a lock-in amplifier. A computer controls a microwave generator to generate microwaves, which are then emitted through a microwave antenna and applied to the NV color centers of the diamond thin film. The radio frequency signal of the microwave system serves as the reference signal for the lock-in amplifier, and the output signal of the lock-in amplifier is connected to the computer. The microwave system provides a modulation signal for the spin resonance of the NV color centers, thereby improving the accuracy of the diamond thin-film magnetic imaging device. Traditional diamond magnetic field imaging devices that use Gaussian beams require repeated movement of the magnetic field to be measured in advance to calibrate the spatial position of the magnetic field image. In other words, existing technology has difficulty determining the corresponding spatial position of the magnetic field image without prior calibration, which greatly limits its application in practical scenarios, especially in the field of magnetic flux leakage detection in large-scale engineering projects, such as the detection of magnetic flux leakage defects in steel wires. This seriously hinders the in-depth research and market development of magnetic field imaging devices. Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, this invention discloses a diamond magnetic field imaging device and method based on an irregularly shaped beam. It utilizes the shape and vertex intensity of the irregularly shaped beam to avoid pre-calibrating the spatial positional relationship between the object under test and the magnetic field. It has a simple structure, high sensitivity, is easy to use, and has good stability.

[0005] The technical solution adopted in this invention is: a diamond magnetic field imaging device based on an irregularly shaped beam, comprising a linearly polarized light excitation unit, a scalar irregularly shaped beam modulation unit, a fluorescence collection and detection unit, and a data processing unit. The linearly polarized light excitation unit emits laser light to the scalar irregularly shaped beam modulation unit, generating a scalar irregularly shaped beam. The scalar irregularly shaped beam passes through the fluorescence collection and detection unit to obtain a fluorescence image containing information about the magnetic field to be measured. The data processing unit processes the ODMR spectral data of each pixel according to the frequency sweep applied by the microwave, and then fits the image of the magnetic field to be measured according to the Lorentz relation.

[0006] The linearly polarized light excitation unit includes a laser, a polarizer, a first lens, a second lens, a first reflector, and a second reflector. The laser emitted from the laser is expanded and collimated by the polarizer, the first lens, and the second lens to generate a linearly polarized beam. The linearly polarized beam is reflected by the first reflector and the second reflector to the scalar irregular beam modulation unit.

[0007] The scalar irregular beam modulation unit includes a spatial light modulator and a spatial filtering system. A linearly polarized beam is generated into a scalar irregular beam by passing through the spatial light modulator and the spatial filtering system. The spatial filtering system includes a third lens, an aperture stop, and a fourth lens arranged sequentially.

[0008] The fluorescence collection and detection unit includes a beam splitter, an objective lens, a magnetic field to be measured, a diamond, a microwave system, a filter, a fifth lens, and a fluorescence detector. The modulated scalar irregular beam is split by the beam splitter and incident on the objective lens. The objective lens then focuses the scalar irregular beam onto the diamond on which the magnetic field to be measured is placed. Simultaneously, the microwave system applies microwaves of 2700MHz to 3000MHz to the diamond. The fluorescence excited under these conditions returns along the same path to the incident filter on the beam splitter, and is then focused by the fifth lens onto the fluorescence detector, resulting in a fluorescence image containing information about the magnetic field to be measured.

[0009] This invention also discloses a method for diamond magnetic field imaging based on an irregularly shaped beam. First, the linear polarization excitation unit expands and collimates the laser emitted from the laser through a polarizer, a first lens, and a second lens to generate a linearly polarized beam. The linearly polarized light is reflected by a first mirror and a second mirror to a scalar irregularly shaped beam modulation unit. The linearly polarized beam passes through a spatial light modulator and a spatial filtering system to generate a scalar irregularly shaped beam. The modulated scalar irregularly shaped beam is split by a beam splitter and incident on the objective lens. The objective lens focuses the scalar irregularly shaped beam onto the diamond on which the magnetic field to be measured is placed. Simultaneously, a microwave system applies microwaves at 2700 MHz to 3000 MHz to the diamond. The fluorescence excited in this state returns along the same path to the incident filter of the beam splitter, and is then focused by a fifth lens onto a fluorescence detector, obtaining a fluorescence image containing information about the magnetic field to be measured. The data processing unit processes the ODMR spectral data of each pixel on the fluorescence detector according to the frequency sweep of the applied microwaves, and then fits the image of the magnetic field to be measured according to the Lorentz relation.

[0010] The Lorentz relationship fitting formula is Pham LM, Sage DL, Stanwix PL, et al. Magnetic field imaging with nitrogen-vacancy ensembles[J]. New Journal of Physics, 2011, 13(4): 045021.

[0011] The laser has a wavelength of 532nm, which is a good excitation effect on the fluorescence of diamond NV color centers.

[0012] The polarizer is either an H-type polarizer or a K-type polarizer.

[0013] The first lens, the second lens, and the fifth lens are made of one of the following materials: ultraviolet fused silica, calcium fluoride, silicon, and zinc selenide.

[0014] The first and second reflectors are high-reflectivity lenses used to reduce energy loss of linearly polarized light.

[0015] The spatial light modulator is one of the following: liquid crystal spatial light modulator, digital micro-reflection spatial light modulator, and photoelectric crystal spatial light modulator.

[0016] The scalar irregular beam is one of the following: triangular, quadrilateral, or pentagonal, with stronger light intensity at its vertices.

[0017] The third and fourth lenses have the same focal length, and the aperture stop is located in the focal area of ​​the third lens. The aperture stop eliminates unwanted patterns and achieves beam shaping.

[0018] The beam splitter is one of the following: a plane beam splitter, a beam splitter prism, or a polarizing beam splitter prism.

[0019] The objective lens has a high numerical aperture (NV) value greater than 1 to ensure fluorescence collection. The objective lens is one of the following: oil immersion objective, achromatic objective, microscope objective, or multiphoton physiological objective.

[0020] The magnetic field to be measured is one of the following: weak magnetic field, strong magnetic field, or leakage magnetic field.

[0021] The diamond mentioned is one of the arbitrary arrangements of a high-concentration NV color center ensemble.

[0022] The microwave system 305 is one of the broadband high-power microwave systems and ultra-wideband high-power microwave systems.

[0023] The filter is one of the high-pass filters with any wavelength in the 550-630nm range.

[0024] The fluorescence detector is one of a single-photon camera or a single-photon detector.

[0025] This invention discloses a diamond magnetic field imaging device and method based on an irregularly shaped beam, the beneficial effects of which are:

[0026] (1) This device uses cross-phase to generate irregularly shaped beams with adjustable shape and geometric sides to calibrate the spatial relationship between the measured magnetic field image and the sample under test. This method not only eliminates the pre-calibration step required by existing technologies, but also improves detection efficiency. It does not require moving the magnetic field under test, making it convenient for large-scale engineering magnetic flux leakage imaging detection.

[0027] (2) This device has a simple structure, is easy to use, and has good stability. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of a diamond magnetic field imaging device and method based on an irregularly shaped beam.

[0030] In the diagram: 101, laser; 102, polarizer; 103, first lens; 104, second lens; 105, first mirror; 106, second mirror; 201, spatial light modulator; 202, third lens; 203, aperture; 204, fourth lens; 211, scalar irregular beam; 301, beam splitter; 302, objective lens; 303, magnetic field to be measured; 304, diamond; 305, microwave system; 306, filter; 307, fifth lens; 308, fluorescence detector; 40, data processing unit. Detailed Implementation

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] To further understand the invention, the invention will be described in detail below with reference to the accompanying drawings:

[0034] like Figure 1 As shown, a diamond magnetic field imaging device based on an irregularly shaped beam includes a linearly polarized light excitation unit, a scalar irregularly shaped beam modulation unit, a fluorescence collection and detection unit, and a data processing unit 40. The linearly polarized light excitation unit emits laser light to the scalar irregularly shaped beam modulation unit, generating a scalar irregularly shaped beam 211. The scalar irregularly shaped beam 211 passes through the fluorescence collection and detection unit to obtain a fluorescence image containing information about the magnetic field 303 to be measured. The data processing unit 40 processes the ODMR spectral data of each pixel according to the frequency sweep applied by the microwave, and then fits the image of the magnetic field 303 to be measured according to the Lorentz relation.

[0035] The linearly polarized light excitation unit includes a laser 101, a polarizer 102, a first lens 103, a second lens 104, a first reflector 105, and a second reflector 106. The laser emitted from the laser 101 is expanded and collimated by the polarizer 102, the first lens 103, and the second lens 104 to generate a linearly polarized beam. The linearly polarized beam is reflected by the first reflector 105 and the second reflector 106 to the scalar irregular beam modulation unit.

[0036] The scalar irregular beam modulation unit includes a spatial light modulator 201 and a spatial filtering system. A linearly polarized beam is generated into a scalar irregular beam 211 by passing through the spatial light modulator 201 and the spatial filtering system. The spatial filtering system includes a third lens 202, an aperture stop 203, and a fourth lens 204 arranged sequentially.

[0037] The fluorescence collection and detection unit includes a beam splitter 301, an objective lens 302, a magnetic field to be measured 303, a diamond 304, a microwave system 305, a filter 306, a fifth lens 307, and a fluorescence detector 308. The modulated scalar irregular beam 211 is split by the beam splitter 301 and incident on the objective lens 302. The objective lens 302 then focuses the scalar irregular beam 211 onto the diamond 304, where the magnetic field to be measured 303 is placed. Simultaneously, the microwave system 305 applies microwaves of 2700MHz to 3000MHz to the diamond 304. The fluorescence excited by this process returns to the beam splitter 301 and is incident on the filter 306, then focused by the fifth lens 307 onto the fluorescence detector 308, resulting in a fluorescence image containing information about the magnetic field to be measured 303.

[0038] This invention also discloses a method for a diamond magnetic field imaging device based on an irregularly shaped beam. First, the linearly polarized excitation unit, where the laser emitted from laser 101 is expanded and collimated by polarizer 102, first lens 103, and second lens 104, generates a linearly polarized beam. The linearly polarized beam is reflected by first mirror 105 and second mirror 106 to a scalar irregularly shaped beam modulation unit. The linearly polarized beam then passes through spatial light modulator 201, third lens 202, aperture 203, and fourth lens 204 to generate a scalar irregularly shaped beam 211. The modulated scalar irregular beam 211 is split by the beam splitter 301 and incident on the objective lens 302. The scalar irregular beam 211 is then focused by the objective lens 302 onto the diamond 304 on which the magnetic field to be measured 303 is placed. Simultaneously, the microwave system 305 applies microwaves of 2700MHz to 3000MHz to the diamond 304. The fluorescence excited in this state returns to the incident filter 306 of the beam splitter 301, and is then focused onto the fluorescence detector 308 by the fifth lens 307, resulting in a fluorescence image containing information about the magnetic field to be measured 303. Finally, the data processing unit 40 processes the ODMR spectral data of each pixel on the fluorescence detector 308 according to the frequency sweep of the applied microwave, and then fits the image of the magnetic field to be measured 303 according to the Lorentz relation.

[0039] In this embodiment, the transfer function T of the cross phase loaded on the spatial light modulator 201 is expressed as:

[0040] T = uxpyq (1)

[0041] Where u represents the conversion rate, and the sum of the exponents p and q is the geometric number of the scalar irregular beam.

[0042] The Lorentz relationship fitting formula is Pham LM, Sage DL, Stanwix PL, et al. Magnetic field imaging with nitrogen-vacancy ensembles[J]. New Journal of Physics, 2011, 13(4): 045021.

[0043] The laser 101 has a wavelength of 532nm.

[0044] The polarizer 102 is one of an H-type polarizer and a K-type polarizer.

[0045] The materials of the first lens 103, the second lens 104 and the fifth lens 307 are one of ultraviolet fused silica, calcium fluoride, silicon and zinc selenide.

[0046] The first reflector 105 and the second reflector 106 are high-reflectivity lenses. The higher the reflectivity of the reflector, the better, in order to reduce the energy loss of linearly polarized light.

[0047] The spatial light modulator 201 is one of a liquid crystal spatial light modulator, a digital micro-reflection spatial light modulator, and an optoelectronic crystal spatial light modulator.

[0048] The scalar irregular beam 211 is one of a triangle, a quadrilateral, or a pentagon, and its vertex has a stronger light intensity.

[0049] The third lens 202 and the fourth lens 204 have the same focal length. The aperture stop 203 is located in the focal area of ​​the third lens 202 and is used to filter out stray light that interferes with the irregular beam, filter out the first-order diffraction spot with irregular characteristics, eliminate unwanted modes, and realize beam shaping.

[0050] The beam splitter 301 is one of a plane beam splitter, a beam splitter prism, or a polarizing beam splitter prism.

[0051] The objective lens 302 is one of an oil immersion objective lens, an achromatic objective lens, a microscope objective lens, or a multiphoton physiological objective lens. The high numerical aperture (NV) value of objective lens 302 is greater than 1.

[0052] The magnetic field to be measured 303 is one of weak magnetic field, strong magnetic field, and leakage magnetic field.

[0053] The diamond 304 mentioned is one of the arbitrary arrangements of a high-concentration NV color center ensemble.

[0054] The microwave system 305 is one of the broadband high-power microwave systems and ultra-wideband high-power microwave systems.

[0055] The filter 306 is one of the high-pass filters with any wavelength in the 550-630nm range.

[0056] The fluorescence detector 308 is one of a single-photon camera and a single-photon detector.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A diamond magnetic field imaging device based on an irregularly shaped beam, characterized in that, The system includes a linearly polarized light excitation unit, a scalar irregular beam modulation unit, a fluorescence collection and detection unit, and a data processing unit (40). The linearly polarized light excitation unit emits a laser to the scalar irregular beam modulation unit to generate a scalar irregular beam (211). The scalar irregular beam (211) passes through the fluorescence collection and detection unit to obtain a fluorescence image containing information about the magnetic field to be measured (303). The data processing unit (40) processes the ODMR spectral data of each pixel according to the frequency sweep applied by the microwave, and then fits the image of the magnetic field to be measured (303) according to the Lorentz relationship. The irregular beam modulation unit includes a spatial light modulator (201) and a spatial filtering system. A linearly polarized beam is generated into a scalar irregular beam (211) by passing through the spatial light modulator (201) and the spatial filtering system. The spatial filtering system includes a third lens (202), an aperture (203), and a fourth lens (204) arranged in sequence. The linearly polarized light excitation unit includes a laser (101), a polarizer (102), a first lens (103), a second lens (104), a first mirror (105), and a second mirror (106). The laser (101) emits light... The laser beam is expanded and collimated by a polarizer (102), a first lens (103), and a second lens (104) to generate a linearly polarized beam. The linearly polarized beam is reflected by a first mirror (105) and a second mirror (106) to a scalar irregular beam modulation unit. The fluorescence collection and detection unit includes a beam splitter (301), an objective lens (302), a magnetic field to be measured (303), a diamond (304), a microwave system (305), a filter (306), a fifth lens (307), and a fluorescence detector (308). The modulated scalar irregular beam (2 11) The beam is split by the beam splitter (301) and incident on the objective lens (302). The scalar irregular beam (211) is focused by the objective lens (302) onto the diamond (304) on which the magnetic field to be measured (303) is placed. At the same time, the microwave system (305) applies microwaves of 2700MHz to 3000MHz to the diamond (304). The fluorescence excited in this state returns to the incident filter (306) of the beam splitter (301) and is then focused onto the fluorescence detector (308) by the fifth lens (307) to obtain a fluorescence image containing information of the magnetic field to be measured (303).

2. The diamond magnetic field imaging device based on an irregularly shaped beam according to claim 1, characterized in that, The laser (101) has a wavelength of 532nm.

3. The diamond magnetic field imaging device based on an irregularly shaped beam according to claim 1, characterized in that, The polarizer (102) is one of the H-type polarizer and the K-type polarizer.

4. The diamond magnetic field imaging device based on an irregularly shaped beam according to claim 1, characterized in that, The materials of the first lens (103) and the second lens (104) are one of ultraviolet fused silica, calcium fluoride, silicon, and zinc selenide.

5. A diamond magnetic field imaging device based on an irregularly shaped beam according to claim 1, characterized in that, The spatial light modulator (201) is one of a liquid crystal spatial light modulator, a digital micro-reflection spatial light modulator, and an optoelectronic crystal spatial light modulator.

6. The diamond magnetic field imaging device based on an irregularly shaped beam according to claim 1, characterized in that, The scalar irregular beam (211) is one of the following: triangle, quadrilateral, or pentagon, and the light intensity at its vertex is relatively strong.

7. A diamond magnetic field imaging device based on an irregularly shaped beam according to claim 1, characterized in that, The third lens (202) and the fourth lens (204) have the same focal length, and the aperture stop (203) is located in the focal area of ​​the third lens (202).

8. A diamond magnetic field imaging device based on an irregularly shaped beam according to claim 1, characterized in that, The beam splitter (301) is one of the following: a plane beam splitter, a beam splitter prism, or a polarizing beam splitter prism.

9. A diamond magnetic field imaging device based on an irregularly shaped beam according to claim 1, characterized in that, The objective lens (302) is one of an oil immersion objective lens, an achromatic objective lens, a microscope objective lens, or a multiphoton physiological objective lens; the objective lens (302) has a high numerical aperture (NV) value greater than 1.

10. A diamond magnetic field imaging device based on an irregularly shaped beam according to claim 1, characterized in that, The magnetic field to be measured (303) is one of weak magnetic field, strong magnetic field, or leakage magnetic field.

11. A diamond magnetic field imaging device based on an irregularly shaped beam according to claim 1, characterized in that, The diamond (304) mentioned is one of the arbitrary arrangements of a high-concentration NV color center ensemble.

12. The diamond magnetic field imaging device based on an irregularly shaped beam according to claim 1, characterized in that, The microwave system (305) is one of the broadband high-power microwave systems and ultra-wideband high-power microwave systems.

13. A diamond magnetic field imaging device based on an irregularly shaped beam according to claim 1, characterized in that, The filter (306) is one of the high-pass filters with any wavelength in the range of 550-630nm.

14. A diamond magnetic field imaging device based on an irregularly shaped beam according to claim 1, characterized in that, The fluorescence detector (308) is one of a single-photon camera and a single-photon detector.

15. A method for diamond magnetic field imaging based on an irregularly shaped beam, characterized in that, Applied to any one of claims 1 to 14, a diamond magnetic field imaging device based on an irregular beam is firstly generated by a linearly polarized excitation unit. The laser emitted from the laser (101) is expanded and collimated by a polarizer (102), a first lens (103), and a second lens (104) to produce a linearly polarized beam. The linearly polarized beam is reflected by a first mirror (105) and a second mirror (106) to a scalar irregular beam modulation unit. The linearly polarized beam passes through a spatial light modulator (201), a third lens (202), an aperture (203), and a fourth lens (204) to produce a scalar irregular beam (211). The modulated scalar irregular beam (211) is split by a beam splitter (301) and incident on the objective lens (302). The scalar irregular beam (211) is focused by the objective lens (302) onto the diamond (304) on which the magnetic field to be measured (303) is placed. At the same time, the microwave system (305) applies microwaves of 2700MHz to 3000MHz to the diamond (304). The fluorescence excited in this state returns to the incident filter (306) of the beam splitter (301) and is then focused onto the fluorescence detector (308) by the fifth lens (307) to obtain a fluorescence image containing information about the magnetic field to be measured (303). Finally, the data processing unit (40) processes the ODMR spectral data of each pixel on the fluorescence detector (308) according to the frequency sweep applied by the microwave, and then fits the image of the magnetic field to be measured (303) according to the Lorentz relationship.

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