Negative pressure adsorption type optical fiber probe based on diamond nv color center and magnetic scanning platform

Abstract

The utility model relates to the field of precision measurement and optical fiber sensing technology discloses a kind of negative pressure adsorption type optical fiber probe and magnetic scanning platform based on diamond NV color center, and optical fiber probe includes hollow optical fiber main part, and the inside diameter of its one end portion is less than the particle size of diamond particle containing NV color center, so that diamond particle is physically stopped by inner wall edge when close to the end portion;Miniature air pump is used to provide positive pressure or negative pressure;Wherein, miniature air pump is connected with gas path switching valve;Adapter is arranged between the other end of hollow optical fiber main body and gas path switching valve, for sealingly connecting hollow optical fiber main body to gas path switching valve;Flexible air pipe is connected between adapter and gas path switching valve, for transmitting gas between hollow optical fiber main body and gas path switching valve.The utility model uses adsorption type structure, solves the problem of poor laser damage resistance, easy failure and reduced fluorescence collection efficiency caused by optical adhesive bonding in the prior art.

Description

Technical Field

[0001] This utility model relates to the fields of precision measurement and fiber optic sensing technology, specifically to a negative pressure adsorption fiber optic probe and magnetic scanning platform based on diamond NV color centers. Background Technology

[0002] Magnetic imaging technology based on diamond particles is currently a research hotspot for high-sensitivity, high-spatial-resolution magnetic field sensing. Among them, the scanning probe measurement scheme constructs a sensing probe by fixing micron-sized diamond particles to the end of an optical fiber. Combined with optical path, microwave and other modules, it can perform point-by-point scanning magnetic imaging of the sample surface, and is widely used in fields such as metal surface crack detection and chip defect analysis.

[0003] In existing technologies, optical adhesives (such as UV adhesives) are commonly used to fix diamond particles to the ends of optical fibers. However, in practical applications, high-power lasers are often required to excite NV color center fluorescence in order to achieve high signal-to-noise ratio measurements. Under prolonged exposure to high-power lasers, the optical adhesive undergoes photothermal degradation, gradually turning black, carbonizing, and charring, leading to two serious problems: First, the carbonized layer severely hinders the collection efficiency of the fluorescence signal, reducing probe sensitivity; second, the adhesive bonding force is lost, causing the diamond particles to easily detach, resulting in probe failure. Therefore, existing adhesive bonding methods severely limit the usable laser power and long-term operational stability of the probe. Utility Model Content

[0004] This application provides a negative pressure adsorption fiber optic probe and magnetic scanning platform based on diamond NV color centers, which can solve the technical problems of poor resistance to laser damage, easy failure, and reduced fluorescence collection efficiency caused by the use of optical adhesive to bond existing diamond particle fiber optic probes.

[0005] The solution presented in this application is implemented through the following steps.

[0006] In a first aspect, an example of this application discloses a negative pressure adsorption fiber optic probe based on diamond NV centers, comprising: The hollow optical fiber body has an inner diameter at one end that is smaller than the particle size of the diamond particles containing the NV color center, so that the diamond particles are physically stopped by the inner wall edge when they come into contact with that end. A miniature air pump is used to provide positive or negative pressure; wherein the miniature air pump is connected to an air path switching valve for switching between positive pressure output state, negative pressure input state and off state; An adapter is provided between the other end of the hollow optical fiber body and the gas path switching valve, for sealingly connecting the hollow optical fiber body to the gas path switching valve. A flexible air tube is connected between the adapter and the air path switching valve for transmitting gas between the hollow optical fiber body and the air path switching valve. Specifically, when the gas path switching valve is in a negative pressure input state, the diamond particles are adsorbed and fixed at the physical stop position at the end of the hollow optical fiber body. When the gas path switching valve is in a positive pressure output state, the diamond particles are released from the physical stop position.

[0007] This application employs a hollow optical fiber structure. One end is connected to a micro air pump via an adapter and air tube to generate negative pressure. The other end uses negative pressure to attract diamond particles for detection. This eliminates the need for optical adhesives, avoiding the problems of colloid ablation, blackening, and carbonization under high-power laser irradiation. The probe exhibits excellent photothermal stability. Furthermore, the inner diameter of the hollow optical fiber's end is smaller than the diamond particle size. The internal edge of the end forms a physical stop and fixation for the diamond particles. This physical stop structure is simple and reliable, ensuring stable positioning of the diamond particles after adsorption. It is not easily affected by vibration or airflow interference, enabling rapid and non-destructive loading and unloading of diamond particles without the need for realignment. This greatly improves measurement efficiency and flexibility and can accommodate diamond particles of different sizes or NV center concentrations. Moreover, the combination of the adapter and flexible air tube achieves a reliable seal from the micron-sized hollow optical fiber to the standard air path, facilitating connection with pneumatic components.

[0008] In the negative pressure adsorption fiber optic probe based on diamond NV color centers as described above, optionally, the inner diameter of the hollow fiber body is 0.3 to 0.9 times the particle size of the diamond particles.

[0009] Using a suitable inner diameter ratio can ensure negative pressure on the diamond particles, while preventing the diamond particles from getting stuck in the tube. The distance of the diamond particles protruding from the end face is controllable, meeting the working distance requirements of near-field measurement (usually less than 5μm) and realizing high-resolution magnetic imaging.

[0010] As described above, the negative pressure adsorption fiber optic probe based on diamond NV color centers can optionally include a three-way solenoid valve. The first port of the three-way solenoid valve is connected to the positive pressure outlet air path of the micro air pump, the second port of the three-way solenoid valve is connected to the negative pressure inlet air path of the micro air pump, and the third port of the three-way solenoid valve is connected to the internal air path of the hollow fiber body. The switching between positive pressure output and negative pressure input is achieved by controlling the switching state of the three-way solenoid valve.

[0011] The solenoid valve provides a fast response (millisecond level) for switching the gas path, enabling rapid cycling of diamond particle loading, measurement, and unloading. Furthermore, the three-way solenoid valve's positive / negative pressure separation design avoids gas cross-interference, ensuring negative pressure stability and positive pressure blowing effect. In addition, it is easy to link with a computer or PLC to achieve automated control.

[0012] As described above, in the negative pressure adsorption fiber optic probe based on diamond NV centers, optionally, the relative vacuum degree generated by the micro air pump is not less than -50 kPa.

[0013] By employing an appropriate relative vacuum, diamond particles can be reliably adsorbed under various operating conditions (including vibration, tilt, and airflow interference), preventing accidental detachment of diamond particles due to insufficient suction and improving measurement stability.

[0014] As described above, in the negative pressure adsorption fiber optic probe based on diamond NV centers, the micro pump may optionally include a micro diaphragm pump or a peristaltic pump.

[0015] Both diaphragm pumps and peristaltic pumps are oil-free, avoiding oil mist contamination of optical components and diamond particles. They can withstand a certain level of dust or tiny diamond particles, are not easily clogged, have a long lifespan, and are easy to maintain.

[0016] As described above, the negative pressure adsorption fiber optic probe based on diamond NV centers may optionally include a microfluidic adapter.

[0017] Microfluidic adapters can achieve reliable sealing from micron-level tubes to millimeter-level gas paths, facilitate connection with standard pneumatic components, and have good sealing performance, capable of withstanding repeated positive and negative pressure impacts; they also facilitate quick replacement of hollow optical fiber bodies of different specifications.

[0018] The negative pressure adsorption fiber optic probe based on diamond NV centers as described above may optionally include a gas filter connected in series between the micro air pump and the adapter, wherein the pore size of the gas filter is no greater than 0.5 micrometers.

[0019] A gas filter is used to intercept environmental dust, diamond fragments, or dispersion residues, preventing particles from entering the hollow optical fiber body and causing blockage, thus extending the overall lifespan of the probe. It also prevents diamond particles from getting stuck at the stop surface and affecting the subsequent adsorption effect. In addition, the filter can be replaced or cleaned, making maintenance convenient.

[0020] The second aspect of this application provides a magnetic scanning platform, including a negative pressure adsorption fiber optic probe based on diamond NV color centers as described in any of the first aspects above.

[0021] Employing a glue-free probe with quickly replaceable diamond particles, the platform can withstand continuous operation with high-power lasers (>100mW) without frequent shutdowns for probe replacement. Different diamond particles can be quickly switched, facilitating comparative experiments with different NV center concentrations or particle sizes. Overall maintenance costs are low, making it suitable for use in industrial settings and research laboratories. Attached Figure Description

[0022] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of this application are illustrated by way of example and not limitation, and the same or corresponding reference numerals denote the same or corresponding parts, wherein: Figure 1 A schematic diagram of a negative pressure adsorption fiber optic probe based on diamond NV color centers provided by this utility model; Figure 2 A schematic diagram of a negative pressure adsorption fiber optic probe based on diamond NV color centers, including a gas filter, provided for this utility model; Figure 3 This is a schematic diagram of the structure of a magnetic scanning platform provided by this utility model.

[0023] Explanation of markings in the diagram: 1-Hollow optical fiber body; 2-Miniature air pump; 3-Adapter; 4-Flexible air tube; 5-Diamond particles; 6-Gas filter; 10-Fiber optic probe; 11-Microwave source; 12-Antenna; 13-Objective lens; 14-Sample. Detailed Implementation

[0024] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0025] like Figure 1 As shown, this embodiment provides a negative pressure adsorption fiber optic probe based on diamond NV color centers, including a miniature air pump 2, an adapter, and a hollow fiber body 1 connected by an air path. The miniature air pump 2 provides negative pressure to adsorb diamond particles 5 onto the end of the hollow fiber body 1 to realize the function of a probe.

[0026] Specifically, the hollow optical fiber body 1 has an inner diameter at one end smaller than the particle size of the diamond particles 5 containing the NV color centers, so that the diamond particles 5 are physically stopped by the inner wall edge when they approach this end. The hollow optical fiber body 1 serves as the carrier for the diamond particles 5, and its inner diameter at the end is smaller than the particle size of the diamond particles 5, forming a physical stopping surface. For example, to adsorb 50 µm diamond particles 5, the inner diameter at the end of the hollow optical fiber body 1 is slightly smaller than the diamond particles 5, using 30-45 µm, so that the diamond particles 5 can be physically stopped and held in the opening at the end, preventing them from being sucked into the interior and forming an effective sealing surface. If compatibility with multiple sizes is required, several hollow optical fiber bodies 1 with different inner diameters can be prepared as replaceable suction nozzles. The shape of the diamond particles 5 may be a regular sphere or an irregular sphere; in this embodiment, the particle size refers to the maximum diameter of the diamond particles 5.

[0027] In addition, physical stop structures are not limited to reduced end inner diameter; they can also be stop components in the form of microporous filter membranes, cross supports, or annular protrusions at the port.

[0028] As an example, the hollow optical fiber body 1 can be made of one of the following: a quartz capillary, a hollow photonic crystal fiber, a glass capillary, or a hollow tube made of polymer material, as long as it has a hollow inner cavity and the inner diameter of its end is smaller than the particle size of the diamond particles 5. In this embodiment, a quartz capillary is preferred, as it has the best compatibility with existing optical fiber systems, is transparent, and is easy to clean. In addition, an anti-resonant hollow optical fiber can also be used, which has an even smaller inner diameter (52 µm) and is suitable for extremely fine diamond particles 5.

[0029] The miniature air pump 2 is connected to the internal air passage of the hollow optical fiber body 1 via a flexible air tube 4, and is used to provide positive or negative pressure; wherein, the miniature air pump 2 is connected to an air passage switching valve (attached). Figure 1 (Not shown in the diagram) One end of the air path switching valve is connected to the air path of the micro air pump 2, and the other end is connected to the air path of the inner cavity of the hollow optical fiber body 1. It is used to switch between positive pressure output state, negative pressure input state and closed state.

[0030] For example, the micro air pump 2 can be a diaphragm pump, peristaltic pump, piston pump or piezoelectric pump, as long as it can generate a sufficient positive and negative pressure difference. The air path switching valve that works with it can be a manual three-way valve, electric three-way valve, clamp valve or integrated microfluidic chip valve, etc.

[0031] The hollow optical fiber body 1 typically has a very small outer diameter (e.g., 125 μm), making it impossible to connect directly to a standard gas tube. An adapter 3 (e.g., a tapered clamp, threaded ferrule, or epoxy-sealed connector) can be used to seal and fix the fiber end, and then adapt it to a flexible gas tube 4 (e.g., FEP, PTFE, or silicone tubing). The flexible gas tube 4 is then connected to a gas path switching valve. In this embodiment, a microfluidic adapter with a tapered clamp is preferred, sealing the end of the hollow optical fiber body 1 to a 1 / 16-inch diameter FEP tube, which is then connected to the gas path.

[0032] For example, adapter 3 can be a commercially available fiber optic connector (such as FC / PC type) after modification; or the hollow fiber can be directly inserted into the heat shrink tubing or silicone tube and then sealed with glue (when sealing, the glue should be kept away from the optical path).

[0033] Preferably, the adapter 3 includes a microfluidic adapter. The microfluidic adapter typically employs a tapered clamp, threaded ferrule, or O-ring sealing structure to securely clamp and seal the hollow optical fiber body 1 with an outer diameter of 125 μm, while providing a standard interface (such as 1 / 16 inch or 1 / 32 inch) for connecting to the flexible tubing 4.

[0034] Microfluidic adapters can achieve reliable sealing from micron-level tubes to millimeter-level gas paths, facilitate connection with standard pneumatic components, and have good sealing performance, capable of withstanding repeated positive and negative pressure impacts; they also facilitate quick replacement of hollow optical fiber bodies of different specifications.

[0035] For example, the flexible tubing 4 includes FEP tubing with an outer diameter of 1 / 16 inch. 1 / 16 inch (approximately 1.6 mm) is a standard size in the field of microfluidics. FEP (perfluoroethylene propylene copolymer) has excellent chemical stability, a low coefficient of friction, and low permeability, which prevents gas adsorption contamination. In addition, the transparent FEP material makes it easy to observe whether there is any blockage or liquid condensation in the gas passage. The 1 / 16 inch standard size also makes it easy to purchase and replace.

[0036] The adapter 3 and flexible air tube 4 are used to achieve reliable sealing from micron-level tube to millimeter-level air circuit, which is convenient for connection with standard pneumatic components. In addition, the flexible air tube 4 is resistant to bending and corrosion, and facilitates the movement and wiring of the probe on the scanning platform.

[0037] Specifically, when switching to the negative pressure input state, a negative pressure airflow is generated inside the hollow optical fiber body 1. External air carrying diamond particles 5 flows towards the port at the end of the hollow optical fiber body 1. The diamond particles 5 are intercepted by the physical stop position and tightly adsorbed at the port, achieving stable fixation by atmospheric pressure difference. When switching to the positive pressure output state, a positive pressure airflow is generated inside the cavity, blowing the diamond particles 5 away from the port for rapid release. When switching to the closed state, the air circuit operation stops, maintaining the current state or allowing the diamond particles 5 to fall off naturally.

[0038] In addition to the aforementioned state switching, this embodiment also provides a loading and unloading operation process for diamond particles 5. During loading, the tip of the hollow optical fiber body 1 is immersed in the dispersion liquid (or dry powder tray) containing the diamond particles 5. A micro-negative pressure is activated by the micro air pump 2, and the diamond particles 5 are drawn towards the tip under the influence of the air / liquid flow and are stopped by a physical stop, thus completing the alignment and fixation. At the same time, the pressure can be finely adjusted under microscopic monitoring to achieve single-particle pickup.

[0039] When using it, maintain a weak negative pressure (a few kPa is sufficient) to stably fix the diamond particle 5 on the end face for testing; the magnitude of the negative pressure needs to be determined experimentally, which should resist light pressure and heat convection, but not too large to cause the diamond particle 5 to vibrate slightly.

[0040] When diamond particles 5 need to be unloaded, the micro air pump 2 and the air path switching valve are switched to a slightly positive pressure (or the negative pressure is directly turned off and gravity is used) to blow the diamond particles 5 off or let them fall off naturally, and they can be recycled into the collector.

[0041] This application employs a hollow optical fiber body 1, with one end connected to a micro air pump 2 via an adapter 3 and a flexible air tube 4 to generate negative pressure. The other end uses negative pressure to attract diamond particles 5 for detection. This eliminates the need for optical adhesives, avoiding the problems of colloid ablation, blackening, and carbonization under high-power laser irradiation. The probe exhibits excellent photothermal stability. Furthermore, the inner diameter of the end of the hollow optical fiber body 1 is smaller than the particle size of the diamond particles 5. The internal edge of the end forms a physical stop and fixation for the diamond particles 5. The physical stop structure is simple and reliable, and the diamond particles 5 are stable after adsorption, making them less susceptible to vibration or airflow interference. This allows for rapid and non-destructive loading and unloading of diamond particles 5 without the need for realignment, greatly improving measurement efficiency and flexibility. It can also adapt to diamond particles 5 with different particle sizes or different NV color center concentrations. Moreover, the combination of the adapter 3 and the flexible air tube 4 achieves a reliable seal from the micron-sized hollow optical fiber to the standard air path, facilitating connection with pneumatic components.

[0042] In one implementation, the inner diameter of the hollow optical fiber body 1 is 0.3 to 0.9 times the diameter of the diamond particles 5. Specifically, the inner diameter ratio and the stopping position of the diamond particles 5 can be defined, preferably with an inner diameter ratio of 0.3 to 0.9 times (for example, when the diameter of the diamond particles 5 is 50 μm, the inner diameter is selected as 15 to 45 μm), to ensure that the diamond particles 5 cannot enter the tube, while forming a good sealing surface.

[0043] The inner diameter ratio can be adjusted according to the shape of the diamond particle 5. For example, for spherical diamond particles 5, the lower limit can be as low as 0.3 times, and for irregular diamond particles 5, it is preferably 0.5 to 0.9 times. In addition, the stop position can be precisely positioned by machining a step or annular groove on the inner wall of the port.

[0044] Using a suitable inner diameter ratio can ensure the negative pressure effect on the diamond particle 5, while preventing the diamond particle 5 from getting stuck in the tube. The distance of the protruding end face of the diamond particle 5 is controllable, which meets the requirements of near-field measurement for working distance (usually less than 5μm) and realizes high-resolution magnetic imaging.

[0045] In this embodiment, the pressure in the gas path provides three states: positive pressure, negative pressure, and closed. This can be achieved using a gas path switching valve. Specifically, the gas path switching valve includes a three-way solenoid valve. The first port of the three-way solenoid valve is connected to the positive pressure outlet gas path of the micro air pump 2, the second port of the three-way solenoid valve is connected to the negative pressure inlet gas path of the micro air pump 2, and the third port of the three-way solenoid valve is connected to the internal cavity gas path of the hollow optical fiber body 1. The switching between positive pressure output and negative pressure input is achieved by controlling the switching state of the three-way solenoid valve.

[0046] By utilizing the switching function of the three-way solenoid valve, the positive pressure outlet or negative pressure inlet of the miniature air pump 2 can be selectively connected to the hollow optical fiber body 1. When the first port and the third port are connected, positive pressure is output; when the second port and the third port are connected, negative pressure is input; when all ports are closed, the air path remains closed.

[0047] In addition, a two-position three-way solenoid valve (normally closed or normally open) or an integrated proportional valve can be used to achieve continuous pressure regulation. Alternatively, two independent on / off valves can be used to control the positive and negative pressure pipelines respectively, in conjunction with logic control.

[0048] The solenoid valve provides a fast response (millisecond level) for switching the gas path, enabling rapid cycling of loading, measuring, and unloading diamond particles. The three-way solenoid valve's positive / negative pressure separation design avoids gas cross-interference, ensuring negative pressure stability and positive pressure blowing effect. Furthermore, it is easy to link with a computer or PLC to achieve automated control.

[0049] When a negative pressure condition is required, the relative vacuum level generated by the micro air pump 2 is not less than -50 kPa. Using the micro air pump 2 to provide a vacuum level of at least -50 kPa (absolute pressure approximately 51 kPa) is sufficient to generate sufficient suction. For diamond particles 5 with a diameter of 50 μm, the suction force generated by the -50 kPa negative pressure at the port of the 50 μm particle is approximately 0.1 N, which is sufficient to counteract the gravity and slight vibrations of the diamond particle 5.

[0050] The relative vacuum level generated by the micro air pump 2 can be determined according to the size of the adsorbed diamond particles 5. For example, for smaller diamond particles 5 (such as 10 μm), less suction force is required, and -20 kPa is sufficient. In addition, the negative pressure can be steplessly adjusted by adjusting the PWM or a proportional valve to accommodate different diamond particle sizes 5.

[0051] By employing a suitable relative vacuum, it can be ensured that diamond particles 5 can be reliably adsorbed under various operating conditions (including vibration, tilt, and airflow interference), avoiding accidental detachment of diamond particles 5 due to insufficient suction and improving measurement stability.

[0052] When selecting a micropump to provide positive or negative pressure, the micro air pump 2 includes a micro diaphragm pump or a peristaltic pump. A micro diaphragm pump compresses gas through the reciprocating motion of a diaphragm, providing both positive and negative pressure simultaneously; it is small, oil-free, and has adjustable flow rate. A peristaltic pump generates airflow by squeezing a flexible tube with rollers; it does not contact the gas, is pollution-free, and easily achieves forward / reverse switching (positive / negative pressure switching). Alternatively, a piezoelectric micropump can be used, utilizing piezoelectric ceramics to drive diaphragm vibration; it is ultra-small, low-power, and suitable for portable devices; or a piston-type micropump can be used, which offers higher pressure but is slightly larger.

[0053] Both diaphragm pumps and peristaltic pumps are oil-free, avoiding oil mist contamination of optical components and diamond particles 5. They can withstand a certain degree of dust or tiny diamond particles 5, are not easily clogged, have a long service life, and are easy to maintain.

[0054] like Figure 2 As shown, optionally, the negative pressure adsorption fiber optic probe also includes a gas filter 6 connected in series between the micro air pump 2 and the adapter 3, installed in the flexible air tube 4 path between the micro air pump 2 and the adapter 3. The filter has a replaceable filter membrane with a pore size ≤0.5μm, used to intercept environmental dust, diamond fragments or dispersion residues, preventing these particles from entering the hollow fiber body 1 and causing blockage, extending the overall life of the probe, and also preventing diamond particles 5 from getting stuck at the stop surface and affecting the subsequent adsorption effect. At the same time, the filter can be replaced or cleaned, making maintenance convenient.

[0055] In this embodiment, preferably, the hollow optical fiber body 1 includes a quartz capillary or a hollow optical fiber. Quartz capillaries are standard products with an outer diameter of 125 μm or smaller, customizable inner diameter, high transparency, easy cleaning, and good compatibility with existing optical fiber systems. Hollow optical fibers (such as hollow photonic crystal fibers) have a special microstructure, with an inner diameter as small as tens of micrometers, suitable for the adsorption of extremely fine particles.

[0056] The quartz material is optically transparent, facilitating observation of particle adsorption and laser excitation. Its 125μm outer diameter is a standard size, allowing direct use with standard fiber optic clamps. It is resistant to high temperatures and chemical corrosion, making it suitable for various measurement environments.

[0057] like Figure 3As shown, based on the same concept, this embodiment also provides a magnetic scanning platform, including a negative pressure adsorption fiber optic probe 10 based on diamond NV centers as described in any of the above claims. The magnetic scanning platform is a system for imaging and measuring the magnetic field distribution on the surface of a sample 14. In addition to the fiber optic probe 10 of this invention, it also includes the following modules: a microwave source 11, an antenna 12, an objective lens 13, and a sample 14. The sample 14 to be tested is fixed on the sample stage, and the end of the fiber optic probe is close to the sample 14; diamond particles are adsorbed on the end face of the fiber optic probe, close to the sample 14.

[0058] Microwave source 11 is a frequency-tunable signal generator connected to antenna 12 via a coaxial cable. Antenna 12, employing a coplanar waveguide or a miniature loop antenna, is positioned near the diamond particle on the fiber optic probe 10 (distance <1mm) to apply a microwave field to the NV color center to drive electron spin resonance. The frequency of microwave source 11 can be swept or modulated at a fixed point by the control system.

[0059] Optical system ( Figure 3 (Not shown in the diagram) The sample includes an excitation laser source (laser), a dichroic mirror, objective lens 13, a filter, and a photodetector (such as an avalanche photodiode, APD, or EMCCD). The excitation light, reflected by the dichroic mirror, is focused by objective lens 13 and illuminates the diamond particle from the side of the fiber optic probe, exciting the NV color center to produce fluorescence. The fluorescence signal is collected by the same objective lens 13, and its intensity is recorded by the detector after passing through the dichroic mirror and filter. The fluorescence intensity changes with the variation of the leakage magnetic field on the surface of sample 14 (Zeeman effect), thus determining the magnetic field distribution.

[0060] In addition, it includes a control system, which comprises a computer, data acquisition card, displacement stage controller, and microwave source control software. The control system coordinates scanning motion, microwave frequency switching, signal acquisition, and image reconstruction.

[0061] The magnetic scanning platform operates as follows: Diamond particles from the fiber optic probe are brought close to the sample surface at a distance of <5μm. A laser is activated to excite the NV centers (nodal luminescence centers). Simultaneously, a microwave source applies a microwave field at the resonant frequency through an antenna, causing a resonant dip in the fluorescence intensity of the NV centers. When a leakage magnetic field exists on the sample surface, the energy levels of the NV centers undergo Zeeman splitting, shifting the resonant frequency and resulting in a change in fluorescence intensity at a fixed microwave frequency. The detector records the fluorescence intensity at that point, reflecting the magnetic field strength at that location. The control system drives the displacement stage to move the sample along a preset path (e.g., grating scanning), acquiring fluorescence signals point by point. After scanning, the control system converts the signal intensity at each location into a grayscale or pseudo-color image, outputting a magnetic field distribution map of the sample.

[0062] Employing a glue-free, highly stable fiber optic probe, the entire magnetic scanning platform can withstand higher-power laser excitation, resulting in a higher signal-to-noise ratio and measurement speed, while also extending probe lifespan and reducing maintenance costs. Prominent diamond particles ensure high spatial resolution, and the robust probe structure prevents diamond particle detachment, making it suitable for precision measurement scenarios such as semiconductor chip defect detection and metal surface micro-crack detection. It eliminates the need for frequent probe replacements, resulting in low maintenance costs.

[0063] In the foregoing description of this application, unless otherwise expressly specified and limited, the terms "fixed," "installed," "connected," or "linked" should be interpreted broadly. For example, the term "linked" can refer to a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; or it can refer to the internal communication of two components or the interaction between two components. Therefore, unless otherwise expressly limited in this application, those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0064] Based on the above description of this application, those skilled in the art will also understand that terms used, such as "upper," "lower," "length," "width," "top," "bottom," "inner," "outer," "axial," "longitudinal," "transverse," "clockwise," or "counterclockwise," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings of this application. These terms are used only for the purpose of facilitating the explanation of the application and simplifying the description, and are not intended to imply that the device or element involved must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the aforementioned orientation or positional relationship terms should not be understood or interpreted as limitations on the application.

[0065] Furthermore, the terms "first" or "second," etc., used in this application to refer to numbers or ordinal numbers are for convenience of description only and should not be construed as explicitly or implicitly indicating relative importance or specifying the number of indicated technical features. Also, a feature specified as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, or more, unless otherwise explicitly specified.

[0066] While numerous embodiments of this application have been shown and described herein, it will be appreciated by those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will arise in the mind and spirit of this application without departing from its intent. It should be understood that various alternatives to the embodiments of this application described herein may be employed in the practice of this application. The appended claims are intended to define the scope of protection of this application and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. A negative pressure adsorption fiber optic probe based on diamond NV color centers, characterized in that, include: The hollow optical fiber body has an inner diameter at one end that is smaller than the particle size of the diamond particles containing the NV color center, so that the diamond particles are physically stopped by the inner wall edge when they come into contact with that end. A miniature air pump is used to provide positive or negative pressure; wherein the miniature air pump is connected to an air path switching valve for switching between positive pressure output state, negative pressure input state and off state; An adapter is provided between the other end of the hollow optical fiber body and the gas path switching valve, for sealingly connecting the hollow optical fiber body to the gas path switching valve. A flexible air tube is connected between the adapter and the air path switching valve for transmitting gas between the hollow optical fiber body and the air path switching valve. Specifically, when the gas path switching valve is in a negative pressure input state, the diamond particles are adsorbed and fixed at the physical stop position at the end of the hollow optical fiber body. When the gas path switching valve is in a positive pressure output state, the diamond particles are released from the physical stop position.

2. The negative pressure adsorption fiber optic probe based on diamond NV centers according to claim 1, characterized in that, The inner diameter of the hollow optical fiber body is 0.3 to 0.9 times the diameter of the diamond particles.

3. The negative pressure adsorption fiber optic probe based on diamond NV color centers according to claim 1, characterized in that, The gas path switching valve includes a three-way solenoid valve. The first port of the three-way solenoid valve is connected to the positive pressure outlet gas path of the micro air pump, the second port of the three-way solenoid valve is connected to the negative pressure inlet gas path of the micro air pump, and the third port of the three-way solenoid valve is connected to the inner cavity gas path of the hollow optical fiber body. The switching between positive pressure output and negative pressure input is realized by controlling the switching state of the three-way solenoid valve.

4. The negative pressure adsorption fiber optic probe based on diamond NV color centers according to claim 1, characterized in that, The relative vacuum generated by the micro air pump is not less than -50 kPa.

5. The negative pressure adsorption fiber optic probe based on diamond NV color centers according to claim 1, characterized in that, The micro air pump includes a micro diaphragm air pump or a peristaltic pump.

6. The negative pressure adsorption fiber optic probe based on diamond NV color centers according to claim 1, characterized in that, The adapter includes a microfluidic adapter.

7. The negative pressure adsorption fiber optic probe based on diamond NV color centers according to claim 1, characterized in that, It also includes a gas filter connected in series between the micro air pump and the adapter, the gas filter having a pore size of no more than 0.5 micrometers.

8. The negative pressure adsorption fiber optic probe based on diamond NV color centers according to claim 1, characterized in that, The hollow optical fiber body includes a quartz capillary or a hollow optical fiber.

9. A magnetic scanning platform, characterized in that, Including the negative pressure adsorption fiber optic probe based on diamond NV color centers as described in any one of claims 1-8.

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