Quick magnetic tracking quantum magnetic imager without radio frequency microwave

Abstract

The invention belongs to the field of quantum sensors, and discloses a rapid magnetic tracking quantum magnetic imager without radio frequency microwaves, which is a quantum magnetic imager provided by utilizing a color center ensemble rapid induction magnetic field under the condition without microwaves. The instrument is composed of a plurality of systems: an excitation light path, an imaging light path, a detection light path and a magnetic target to be detected. The excitation light path can generate high-quality laser for exciting a to-be-measured target; the imaging light path can be used for quickly positioning a to-be-measured target; the detection light path can collect weak optical signals generated by excitation of the to-be-detected target for further analysis; the fluorescence acquisition and analysis circuit system can collect and detect fluorescence signals in a light path so as to be connected with an upper computer for soft control and accurate analysis processing; air flow is injected into a magnetic target to be detected through the injector, and the magnetic target is controlled to move in the labyrinth-shaped pipeline. The invention provides a valuable method for the rapid magnetic tracking of the magnetic target based on the color center ensemble, so that the application range of the method is expanded.

Description

Technical Field

[0001] The invention relates to the field of quantum sensors, in particular to a quantum magnetic imager for rapid magnetic tracking without radio frequency microwaves. Background Art

[0002] In recent years, more and more researchers have taken the special structure of nitrogen vacancy color center in diamond as an emerging research direction of quantum precision measurement technology, because of its suitable for long-term operation at room temperature, optical spin state initialization and readout, good biocompatibility and other characteristics. Because of the unique structure of NV, it has been fully applied in many fields. Since the fluorescence of NV is very stable, it is a good single-photon source and is used in experiments such as quantum key distribution and bioluminescent labeling. The spin of NV color center can be operated and detected by laser and microwave. In addition, since the coherence time of NV's electron spin can reach milliseconds, it is considered to be a very potential quantum computer system. At the same time, NV can also be used as a nano-sized sensor for measuring physical quantities such as magnetic field, electric field, and temperature. Therefore, how to more conveniently and quickly track, measure and detect is a problem that needs to be solved at present. Summary of the invention

[0003] The purpose of the present invention is to address the problem of how to achieve three-dimensional rapid tracking of magnetic particles in a microwave-free environment, and to provide a quantum magnetic imager for rapid magnetic tracking without radio frequency microwaves. The device can achieve high-precision quantum magnetic tracking of the sample to be tested in a microwave-free environment to analyze the internal situation, and ultimately present high-resolution quantum imaging, which can be effectively applied to entity detection.

[0004] In order to achieve the above purpose, the technical solutions adopted are as follows:

[0005] A quantum magnetic imager for rapid magnetic tracking without radio frequency microwaves, comprising

[0006] The excitation optical path is used to provide stable, high-quality laser light to achieve the excitation of the target to be measured;

[0007] Imaging optical path, used to quickly locate the target to be measured, using a high-resolution, wide-field CMOS camera;

[0008] Detection optical path, collects the weak optical signal generated by the sample to be tested for further analysis;

[0009] The excitation light path, imaging light path and detection light path are installed in the carbon fiber housing.

[0010] As a further improvement of the present invention, the excitation light path includes a laser, a plano-convex lens, a 20x objective lens, a 10μm pinhole camera and a reflector. The laser, plano-convex lens, 20x objective lens and 10μm pinhole camera are coaxially arranged, the reflector is placed at one end of the 10μm pinhole camera, and an imaging light path is arranged on one side of the reflection direction of the reflector; the laser is used to emit 532nm visible green light, the plano-convex lens is used to reduce light reflection and refraction, and focus the emitted laser onto the 20x objective lens and the pinhole camera, the 20x objective lens and the pinhole camera are used to eliminate high-order noise interference and improve imaging quality; the reflector is used to reflect light and provide a light source for the imaging light path.

[0011] As a further improvement of the present invention, the imaging optical path includes a dichroic beam splitter prism, a filter and a CMOS camera. The dichroic beam splitter prism is arranged on one side of the reflection direction of the reflector, the CMOS camera is arranged on a beam of light separated by the dichroic beam splitter prism, and a filter is arranged between the CMOS camera and the dichroic beam splitter prism; the dichroic beam splitter prism is used to separate light of different wavelengths and make it propagate in different directions, the filter is used to filter out light other than the wavelength of 637-800nm, and the CMOS camera is used to realize image acquisition, perform high-resolution detection and imaging.

[0012] As a further improvement of the present invention, the detection light path includes a 10x objective lens, which is arranged on another light path separated by the dichroic beam splitter prism and is used to focus the filtered spots onto the NV color center.

[0013] The beneficial effects of the present invention are:

[0014] The present invention is based on a dual-color center ensemble to achieve rapid tracking of magnetic targets, and has the characteristics of high sensitivity, rapid response and a wide measurement range; in addition, the dual-color center has the advantages of calibration-free and non-invasive detection, allowing rapid acquisition of magnetic field information without spatial scanning, thereby eliminating physical contact between the sensor and the target system, greatly reducing the risk of interference and damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0016] Figure 1 It is a schematic diagram of the optical path of the present invention;

[0017] Figure 2 It is a schematic diagram of the sample to be tested of the present invention. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0019] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0020] Please refer to Figure 1-2 , a quantum magnetic imager for rapid magnetic tracking without radio frequency microwaves, including

[0021] Excitation optical path 1 is used to provide stable high-quality laser to achieve the excitation of the target to be measured;

[0022] The imaging optical path 2 is used to quickly locate the target to be tested. The high-resolution, wide-field-of-view CMOS camera 23 can quickly locate the target position in the sample to be tested, and monitor the position of the sample in real time during the detection process. At the same time, the field of view can be adjusted by adjusting some optical devices.

[0023] Detection optical path 3, collects the weak optical signal generated by the sample to be tested for further analysis;

[0024] The excitation optical path 1, the imaging optical path 2, and the detection optical path 3 are miniaturized and integrated, and the outer shell is packaged by a carbon fiber 3D printed shell.

[0025] The excitation optical path 1 includes a laser 11, a plano-convex lens 12, a 20x objective lens 13, a 10μm pinhole camera 14 and a reflector 15. The laser 11, the plano-convex lens 12, the 20x objective lens 13 and the 10μm pinhole camera 14 are coaxially arranged, the reflector 15 is placed at one end of the 10μm pinhole camera 14, and an imaging optical path 2 is arranged on one side of the reflection direction of the reflector 15; the laser 11 is used to emit 532nm visible green light, the plano-convex lens 12 is used to reduce light reflection and refraction, and focus the emitted laser onto the 20x objective lens 13 and the pinhole camera, the 20x objective lens 13 and the pinhole camera are used to eliminate high-order noise interference and improve imaging quality; the reflector 15 is used to reflect light and provide a light source for the imaging optical path 2.

[0026] The imaging optical path 2 includes a dichroic beam splitter prism 21, a filter 22 and a CMOS camera 23. The dichroic beam splitter prism 21 is arranged on one side of the reflection direction of the reflector 15, and the CMOS camera 23 is arranged on a beam of light separated by the dichroic beam splitter prism 21. The filter 22 is arranged between the CMOS camera 23 and the dichroic beam splitter prism 21; the dichroic beam splitter prism 21 is used to separate light of different wavelengths and make it propagate in different directions, the filter 22 is used to filter out light other than the wavelength of 637-800nm, and the CMOS camera 23 is used to realize image acquisition, perform high-resolution detection and imaging.

[0027] The detection optical path 3 includes a 10x objective lens 31 , which is disposed on another optical path separated by the dichroic beam splitter prism 21 , and is used to focus the filtered spots onto the NV color center 32 .

[0028] A micro track is made to make the magnetic target 33 move stably in the micro track. The track is made by using carbon fiber thin 3D printing to reduce the interference of temperature on the magnetic resonance ODMR signal and reduce the error;

[0029] The magnetic target 33 in the present invention is fixed on the rotating shaft of the DC motor 34 and moves in a circular motion as the motor rotates. The axis of the DC servo motor forms an angle of 30° with the normal vector of the diamond plane 0.5 mm below the magnetic target 33 to ensure the three-dimensional motion of the magnetic target 33 in space.

[0030] A 200μm micro permanent magnet is used as a target and installed in a 3mm×3mm micro track made by 3D printing technology. Then a diamond wrapped in graphite tape with a size of 3mm×3mm×0.5mm is placed, and gas is injected into the track through a syringe to control the movement of the magnetic target 33. The laser 11 is turned on for preheating, and the excitation light is emitted from the laser 11, which is concentrated by the plano-convex lens 12, and then passes through the 20x objective lens 13 and the 10μm pinhole camera 14, reaches the reflector 15 with a reflection angle of 45°, and reaches the dichroic beam splitter prism 21. After being reflected by the dichroic beam splitter prism, it passes through the filter and the CMOS camera 23 in sequence for data collection.

[0031] When exciting and collecting signals, an objective lens is used for focusing, and a plano-convex lens 12 is used for collimation, thereby improving the excitation efficiency and collection efficiency of the optical signal;

[0032] Electronic noise is smaller than laser power noise and is not the main source of noise. By increasing the excitation light power to enhance the fluorescence intensity, the interference of electronic noise is greatly reduced, and the system sensitivity is optimized to 0.5μT / kHz.

[0033] The present invention uses a polarization beam splitter to eliminate the influence of fluorescence noise, then collects fluorescence and excitation light signals simultaneously and converts them to the frequency domain using Fourier transform. Finally, an additional photodetector is combined to record the temporal variation of green light, and the temporal variation of excitation light is subtracted from the collected fluorescence signal, optimizing the laser power noise and improving the signal-to-noise ratio by 10 times.

[0034] The present invention is based on the integrated development of fast magnetic tracking of a dual-color center ensemble. The method can provide millimeter-level magnetic field vector distribution and realize wide-field magnetic imaging. At the same time, compared with the traditional ODMR microwave scanning method, this method does not require a bias magnetic field in a specific direction, saving time in the microwave scanning process and ensuring rapid tracking of magnetic targets. In addition, the dual-color center has the advantages of calibration-free and non-invasive detection, which improves sensitivity and greatly expands the wide measurement range.

[0035] Compared with previous methods, the present invention has the following advantages in terms of scanning magnetic imaging: the present invention does not require microwave frequency sweeping, greatly improves the time resolution of detection, and facilitates the integrated development of fast magnetic tracking based on a two-color center ensemble. In addition, the magnetic detection sensitivity achieved by this research method can reach 0.5μT / kHz, and the spatial resolution is 1.55μm.

[0036] The present invention is superior to the previous methods in terms of the acquisition and analysis circuit system in that the magnetic target in the present invention is fixed on the rotating shaft of the DC motor and moves in a circular motion as the motor rotates. The axis of the DC servo motor forms an angle of 30° with the normal vector of the diamond plane 0.5 mm below the magnetic target to ensure the three-dimensional motion of the magnetic target in space.

[0037] The present invention is a scheme for realizing rapid tracking based on the magnetic field-induced fluorescence change of the two-color center ensemble. Under the condition of continuous polarization of 532nm laser, most of the electron spins are polarized to the ground state energy level, radiating stronger fluorescence. The target magnetic field causes the mixing of the ground state and excited state spin energy levels. The possibility of non-radiative transition increases, more electrons are bound in the ISC transfer, and the polarization of the β-color center slows down. The short-term change of the ground state population|ms=0> leads to a decrease in the polarization of the ground state electrons of the NV-color center, resulting in a decrease in the number of emitted fluorescence photons and a decrease in the fluorescence intensity. In addition, an external magnetic field is applied to the three-color center using an electromagnet, and the magnetic field strength is increased by increasing the current. The system is easy to operate and install, can be used for research based on the two-color center ensemble, improves the sensitivity, which can reach 0.5μT / kHz, and also expands the wide measurement range, ultimately achieving high-resolution and high-speed imaging during the detection process.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A quantum magnetic imager for rapid magnetic tracking without radio frequency microwaves, characterized in that: include The excitation optical path is used to provide stable, high-quality laser light to excite the target to be measured; Imaging optical path, used to quickly locate the target to be measured, using a high-resolution, wide-field CMOS camera; Detection optical path, collects the weak optical signal generated by the sample to be tested for further analysis; The excitation light path, imaging light path and detection light path are installed in the carbon fiber housing.

2. The quantum magnetic imager for rapid magnetic tracking without radio frequency microwaves according to claim 1, characterized in that: The excitation optical path includes a laser, a plano-convex lens, a 20x objective lens, a 10μm pinhole camera and a reflector. The laser, plano-convex lens, 20x objective lens and 10μm pinhole camera are coaxially arranged, the reflector is placed at one end of the 10μm pinhole camera, and an imaging optical path is arranged on one side of the reflection direction of the reflector; the laser is used to emit 532nm visible green light, the plano-convex lens is used to reduce light reflection and refraction, and focus the emitted laser onto the 20x objective lens and the pinhole camera, the 20x objective lens and the pinhole camera are used to eliminate high-order noise interference and improve imaging quality; the reflector is used to reflect light and provide a light source for the imaging optical path.

3. The quantum magnetic imager for rapid magnetic tracking without radio frequency microwaves according to claim 2, characterized in that: The imaging optical path includes a dichroic beam splitter prism, a filter and a CMOS camera. The dichroic beam splitter prism is arranged on one side of the reflection direction of the reflector, the CMOS camera is arranged on a beam of light separated by the dichroic beam splitter prism, and a filter is arranged between the CMOS camera and the dichroic beam splitter prism; the dichroic beam splitter prism is used to separate light of different wavelengths and make it propagate in different directions, the filter is used to filter out light other than the wavelength of 637-800nm, and the CMOS camera is used to realize image acquisition, high-resolution detection and imaging.

4. The quantum magnetic imager for rapid magnetic tracking without radio frequency microwaves according to claim 3 is characterized in that: The detection light path includes a 10x objective lens, which is arranged on another light path separated by the dichroic beam splitter prism and is used to focus the filtered spots onto the NV color center.

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