Three-dimensional microscopic imaging system and method based on double-helix point spread function metalens

Abstract

A three-dimensional microscopic imaging system and method based on a double-helix point spread function metalens, which relates to a three-dimensional microscopic imaging system and method. The present invention aims to solve the problems of poor imaging quality, difficulty in integration and high cost of spatial light modulators. The imaging method of the present invention includes the following steps: S100, designing and processing a metalens with multi-polarization state double-helix point spread function characteristics by simulation means; S200, building an optical system with a metalens as the core for multi-polarization state double-helix point spread function modulation, imaging the molecules to be measured through the metalens, changing the different polarization states of the incident light, and obtaining multiple double-helix images; S300, judging which layer the light spot is in based on the dual basis of polarization state and the distance between the two light spots, determining the lateral position of the molecule to be measured based on the midpoint of the double-helix light spot, and obtaining the axial position based on the angle between the centers of the two light spots combined with the calibration result under the numerical aperture. The present invention belongs to the field of optical microscopic imaging and optical manipulation technology.

Description

Technical Field

[0001] The present invention relates to a three-dimensional microscopic imaging system and method, and belongs to the technical field of optical microscopic imaging and optical manipulation. Background Art

[0002] The point spread function (PSF) describes the imaging system's response to a point source or object. A three-dimensional PSF encodes depth information in the various topographical features of the detected image. Using the known PSF information, the axial information corresponding to each lateral position on the two-dimensional image plane can be restored. Existing methods for modulating the 3D PSF primarily design the amplitude and phase transmittance of the pupil function. By introducing corresponding amplitude and phase modulation at the system's exit pupil plane, the PSF can be adjusted. Light field manipulation is typically achieved using traditional light field manipulation elements, including amplitude / phase masks, spatial light modulators (SLMs), deformable mirrors (DMs), and digital micromirror devices (DMDs). The most commonly used SLM is the one whose phase structure, along with the structural characteristics of the control unit, results in the presence of a zero-order diffraction spot. This zero-order diffraction spot often consumes a significant portion of the energy and often aliases with the modulated effective image, resulting in a dim and blurred displayed image and severely degrading image quality. Furthermore, the large size of SLMs precludes integration into 3D imaging optical systems.

[0003] To address the poor imaging quality, integration difficulties, and high cost of spatial light modulators (SLMs), the concept of metasurfaces has been introduced. The subwavelength structure of metasurfaces can interact with the incident electromagnetic field, thereby introducing abrupt changes in optical parameters on the surface and achieving extraordinary properties not possessed by natural materials. Leveraging the highly integrated nature of metasurfaces, the lens phase is integrated into the modulation of the double-helix point spread function. This improves the zero-order diffraction and integration difficulties of traditional SLM-based three-dimensional imaging optical systems, significantly reducing the size of the components. Furthermore, by leveraging the principle of polarization multiplexing, coaxial, multi-period imaging with different focal lengths is achieved for incident light with different polarization states, extending the axial detection depth while maintaining accuracy. Furthermore, metasurfaces, which are compatible with semiconductor processing, are significantly less expensive to mass-produce than SLMs consisting of controllers, LCD panels, and communication modules, significantly reducing the cost of the entire system and increasing its practicality. Summary of the Invention

[0004] In order to solve the problems of poor imaging quality, difficulty in integration and high cost of spatial light modulators, the present invention proposes a three-dimensional microscopic imaging system and method based on a double-helix point spread function metalens.

[0005] The technical solution adopted by the present invention to solve the above problems is as follows: the steps of the three-dimensional microscopic imaging method based on the double-helix point spread function metalens of the present invention include:

[0006] S100. Design and fabricate a meta-lens with multi-polarization double-helix point spread function characteristics through simulation.

[0007] S200: Build an optical system with a meta-lens as the core to perform multi-polarization double-helix point spread function modulation. Use the meta-lens to image the molecules to be measured, change the different polarization states of the incident light, and obtain multiple double-helix images.

[0008] S300. Determine which repeat the light spot is in based on the dual basis of the polarization state and the distance between the two light spots. Determine the lateral position of the molecule to be measured based on the midpoint of the double helix light spot. Obtain the axial position based on the angle between the centers of the two light spots combined with the calibration result under the numerical aperture.

[0009] Furthermore, the meta-lens forms a complete meta-lens by periodically arranging the basic unit structures according to the double-helix point spread function phase and lens phase distribution through geometric phase and propagation phase arrangement methods.

[0010] Furthermore, the three-dimensional microscopic imaging system based on the double-helix spread function metalens includes an illumination module, a sample stage and an imaging module; the illumination module is arranged on one side of the sample stage, and the imaging module is arranged on the other side of the sample stage; the illumination module includes an LED light source, a collimating lens, a first polarizer and a converging lens, and the LED light source, collimating lens, first polarizer and converging lens are arranged in sequence from left to right; the imaging module includes a metalens, a microscope objective, a second polarizer, a tube lens and a CMOS camera; the metalens, microscope objective, second polarizer, tube lens and CMOS camera are arranged in sequence from left to right.

[0011] The three-dimensional microscopic imaging system based on a double-helix point spread function metalens described in the present invention includes an illumination module, a sample stage and an imaging module; the illumination module is arranged on one side of the sample stage, and the imaging module is arranged on the other side of the sample stage; the illumination module includes an LED light source, a collimating lens, a first polarizer and a converging lens, and the LED light source, collimating lens, first polarizer and converging lens are arranged in sequence from left to right; the imaging module includes a metalens, a microscope objective lens, a second polarizer, a tube lens and a CMOS camera; the metalens, microscope objective lens, second polarizer, tube lens and CMOS camera are arranged in sequence from left to right.

[0012] Furthermore, the steps of the three-dimensional microscopic imaging method based on the above imaging system include:

[0013] Step 1: An LED light source arranged along the beam propagation direction emits a divergent beam with poor coherence, which is converted into parallel light by a collimating lens. The collimated light passes through a first polarizer to generate corresponding polarized light, which is converged by a converging lens onto the sample to be tested, and the sample is placed on the sample stage;

[0014] Step 2: Light passing through the sample passes through the meta-lens, achieving multi-polarization state double-helix point spread function modulation. The modulated image is analyzed by a second polarizer and then imaged again by a microscope system consisting of a microscope objective and a tube lens, and then collected by a CMOS camera.

[0015] Step 3: Decode the acquired double-helix point spread function modulation image. Use the polarization state and the distance between the two spots to determine which repeat the spot is in. Determine the lateral position of the molecule to be measured based on the midpoint of the double-helix spot. Obtain the axial position based on the angle between the centers of the two spots combined with the calibration result under the numerical aperture.

[0016] The double-helix point spread function metalens three-dimensional microscopic imaging system of the present invention comprises an LED light source, a collimating lens, a first polarizer, a converging lens, a half-reflecting half-mirror, a first microscope objective, a sample stage, a first tube lens, a metalens, a second microscope objective, a second polarizer, a second tube lens, and a CMOS camera.

[0017] The LED light source, collimating lens, first polarizer and converging lens are arranged on one side of the half-reflecting half-mirror lens from left to right, the sample stage and the first microscope objective lens are arranged above the half-reflecting half-mirror lens from top to bottom, and the first tube lens, metalens, second microscope objective lens, second polarizer, second tube lens and CMOS camera are arranged below the half-reflecting half-mirror lens from top to bottom.

[0018] The steps of the three-dimensional microscopic imaging method based on the above imaging system include:

[0019] Step 1: An LED light source arranged along the beam propagation direction emits a divergent beam with poor coherence, which is converted into parallel light through a collimating lens. The collimated light passes through a first polarizer to produce corresponding polarized light, which is then converged by a converging lens onto the rear focal plane of a first microscope objective. The first microscope objective has a numerical aperture that matches the size of the details to be resolved on the sample on the sample stage, and can evenly project the beam processed by the half-reflecting, half-mirror lens onto the sample to be inspected;

[0020] Step 2: The first microscope objective collects the light reflected by the sample to be tested, and the light is focused by the first tube lens after passing through the half-reflecting half-mirror lens. The focused light is modulated by the multi-polarization double-helix point spread function through the meta-lens. The modulated image is analyzed by the second polarizer and is secondary imaged by the microscopic system composed of the second microscope objective and the second tube lens, and is collected by the CMOS camera.

[0021] Step 3: Decode the acquired double-helix point spread function modulation image. Use the polarization state and the distance between the two spots to determine which repeat the spot is in. Determine the lateral position of the molecule to be measured based on the midpoint of the double-helix spot. Obtain the axial position based on the angle between the centers of the two spots combined with the calibration result under the numerical aperture.

[0022] Furthermore, the relationship between the focal lengths f1, f2, f3 and the object distance a and image distance b under different polarization states of the metalens satisfies the Gaussian formula

[0023] The beneficial effects of the present invention are as follows: the three-dimensional microscopic imaging method and system based on the multi-polarization state double-helix point spread function meta-lens of the present invention have the advantages of easy integration, no zero-order diffraction spot, and a wide imaging range. In combination with the integrated characteristics of the metasurface, the lens phase is superimposed with the double-helix point spread function phase, which further improves the integration level. The propagation phase is used to design a polarization-multiplexed multi-polarization state double-helix meta-lens, which realizes coaxial and different-focus multi-period connection imaging under different polarization states of incident light, greatly improving the imaging range of the system, and thus can replace the traditional point spread function in the combination of the spatial light modulator and the 4f system. At the same time, it overcomes the shortcomings of the spatial light modulator that has a zero-order diffraction spot that affects the imaging quality and is large in size and difficult to integrate. Through the application of the multi-polarization state double-helix point spread function meta-lens, the three-dimensional information of the sample can be encoded in the rotation angle of the two main lobes of the double-helix spot. By solving the collected two-dimensional intensity information, the three-dimensional depth information can be obtained while obtaining the two-dimensional morphology distribution of the imaging plane. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flow chart of the three-dimensional microscopic imaging method of the present invention;

[0025] Figure 2 It is a schematic diagram of the structure of a transmission-type three-dimensional microscopic imaging system;

[0026] Figure 3 It is a schematic diagram of the structure of a reflective three-dimensional microscopic imaging system;

[0027] Figure 4 Schematic diagram of the phase distribution and amplitude distribution of the meta-lens in the present invention;

[0028] Figure 5 Schematic diagram of simulation results of meta-lenses with different numerical apertures in the present invention;

[0029] Figure 6 This is a schematic diagram of the imaging results of the meta-lens with different polarization states of incidence in the present invention. DETAILED DESCRIPTION

[0030] Specific implementation method 1: Combination Figure 1 This embodiment describes the method for three-dimensional microscopic imaging based on a double-helix point spread function metalens, including the following steps:

[0031] S100. Design and fabricate a meta-lens with multi-polarization double-helix point spread function characteristics through simulation.

[0032] S200: Build an optical system with a meta-lens as the core to perform multi-polarization double-helix point spread function modulation. Use the meta-lens to image the molecules to be measured, change the different polarization states of the incident light, and obtain multiple double-helix images.

[0033] S300. Determine which repeat the light spot is in based on the dual basis of the polarization state and the distance between the two light spots. Determine the lateral position of the molecule to be measured based on the midpoint of the double helix light spot. Obtain the axial position based on the angle between the centers of the two light spots combined with the calibration result under the numerical aperture.

[0034] S101. Optimize the material, shape, and geometric parameters of the metasurface, and perform simulations using the finite element method-based frequency domain calculation module in the electromagnetic simulation software CST. When the unit structure period and nanorod height are constant, by varying the nanorod length and width, find the length and width with the maximum cross-polarization transmittance within a size range suitable for processing, and use this length and width as the unit structure.

[0035] S102. Generate a multi-polarization state dual-helix metalens phase distribution by superimposing the lens phase on the dual-helix point spread function phase. The dual-helix metalens phase distribution is obtained by superimposing Laguerre-Gaussian beams with different mode numbers. Optimization conditions are applied to the pupil plane, point spread function plane, and Laguerre-Gaussian mode plane to obtain an optimized pure phase distribution dual-helix point spread function, which improves energy utilization. The rotational response of the improved dual-helix point spread function only appears in specific regions, which not only avoids sidelobe loss but also ensures that the function has rotational characteristics throughout the entire cross-section but remains approximately unchanged within the specific region. On this basis, the multi-polarization state lens phase that can produce a focusing effect is superimposed. By adjusting the numerical aperture of the lens, multi-polarization state dual-helix metalens phases with different focal points and positioning accuracies can be obtained.

[0036] The specific process of step S100 in this embodiment is as follows:

[0037] S103. Generate a processing file for a multi-polarization double-helix metalens according to the selected unit structure.

[0038] S104. Processing the meta-lens by using electron beam lithography combined with reactive ion beam etching.

[0039] Sapphire crystal (Al2O3) with good transmittance in the visible light band is used as the substrate, on which nanorods made of high refractive index material Si are placed. According to the double-helix point spread function phase and lens phase distribution, the basic unit structure is periodically arranged to form a complete meta-lens.

[0040] Specific implementation method 2: Combination Figure 1 This embodiment describes the method for three-dimensional microscopic imaging based on a double-helix point spread function metalens. The metalens of this embodiment distributes the double-helix point spread function phase and lens phase, and forms a complete metalens by periodically arranging the basic unit structure through geometric phase and propagation phase arrangement methods.

[0041] The meta-lens has different double spiral lens phases under different polarization states. The double spiral lens phase of any channel is determined by the lens phase φ with focusing effect. lens and the double helix point spread function phase φ DHPSF The phase focal length of lenses in different channels is different, which can be expressed as follows:

[0042] φ=φ lens +φ DHPSF .

[0043] The double-helix point spread function in any polarization channel is formed by the superposition of Laguerre-Gaussian functions whose modes are located on the same straight line. The Laguerre-Gaussian beam pattern is:

[0044]

[0045] is the normalized radial coordinate, is the normalized radius of the light spot, w0 is the beam waist radius, To use the Rayleigh distance Normalized axial coordinate, l is the wavelength of incident light, where:

[0046]

[0047]

[0048]

[0049]

[0050] For the ancient phase, is the Laguerre polynomial, n and m are the Laguerre-Gaussian mode numbers, in the double helix point spread function, nm satisfies n=|m|,|m|+2,|m|+4,|m|+6,...., the phase and intensity of the double helix point spread function can be obtained by selecting (1, 1), (3, 5), (5, 9), (7, 13), (9, 17) from the Laguerre-Gaussian modes (m, n) and superposing them with equal weights.

[0051] The double-helix point spread function phase distribution generated by the above steps has a low light energy utilization rate. Three plane constraints are used to improve the modulation efficiency of the point spread function and eliminate the sidelobe effect as much as possible. They are: 1. Pupil plane constraint, which removes the amplitude information and only retains the phase of the double-helix point spread function; 2. Point spread function plane constraint, which introduces a weight function related to the main lobe energy distribution on different focal planes to make the main lobe energy distribution more concentrated; 3. Laguerre-Gaussian mode plane constraint, which decomposes the light field into a linear superposition of Laguerre-Gaussian modes of odd functions of different (m, n) modes, multiplied by the weight function, to ensure that the point spread function has rotation characteristics and the rotation rate remains unchanged.

[0052] The lens phase in any polarization channel can be expressed as:

[0053]

[0054] Where λ is the wavelength of the incident light, x and y are the position coordinates in the plane, and f i is the focal length of the lens, and i represents different polarization states.

[0055] The lens multiplexes three different polarization states of xx, yy, and xy / yx. Since the three polarized lights do not affect each other's responses to the lens when incident, phase distributions of double-helix meta-lenses with different numerical apertures are designed in different polarization channels to obtain the phases required for different polarization states.

[0056] Optimized double helix point spread function phase distribution φ DHPSF like Figure 4 As shown in (a).

[0057] Specific implementation method three: Combination Figure 2To illustrate this embodiment, the three-dimensional microscopic imaging system based on the double-helix spread function metalens described in this embodiment includes an illumination module, a sample stage 5 and an imaging module; the illumination module is arranged on one side of the sample stage 5, and the imaging module is arranged on the other side of the sample stage 5; the illumination module includes an LED light source 1, a collimating lens 2, a first polarizer 3 and a converging lens 4, and the LED light source 1, the collimating lens 2, the first polarizer 3 and the converging lens 4 are arranged in sequence from left to right; the imaging module includes a metalens 6, a microscope objective lens 7, a second polarizer 8, a tube lens 9 and a CMOS camera 10; the metalens 6, the microscope objective lens 7, the second polarizer 8, the tube lens 9 and the CMOS camera 10 are arranged in sequence from left to right.

[0058] In this embodiment, the wavelength of the LED light source 1 can be any wavelength in the visible light band of 400nm-650nm, and the emitted light passes through the collimating lens to produce a parallel beam with good collimation;

[0059] Metalens 6 can independently control multiple polarization states and produce continuously rotating double-helix light spots under different polarization incidence conditions. The rotation center is located at different axial depths, thus achieving periodic connection. The axial detection range of the three-polarization-state double-helix point spread metalens is greater than that of a single polarization state.

[0060] Secondary imaging is performed using a microscope objective lens placed after the meta-lens. The microscope objective lens can be a commercial objective lens and used in conjunction with the tube lens.

[0061] Specific implementation method four: Combination Figure 2 This embodiment describes the method for three-dimensional microscopic imaging based on a double-helix point spread function metalens, including the following steps:

[0062] Step 1: An LED light source 1 arranged along the beam propagation direction emits a divergent beam with poor coherence, which is converted into parallel light by a collimating lens 2. The collimated light passes through a first polarizer 3 to generate corresponding polarized light, which is converged by a converging lens 4 onto the sample to be tested. The sample is then placed on a sample stage 5.

[0063] Step 2: Light passing through the sample passes through the meta-lens 6 to achieve multi-polarization state double-helix point spread function modulation. The modulated image is analyzed by the second polarizer 8 and is secondary imaged by the microscope system consisting of the microscope objective 7 and the tube lens 9, and is collected by the CMOS camera 10.

[0064] Step 3: Decode the acquired double-helix point spread function modulation image. Use the polarization state and the distance between the two spots to determine which repeat the spot is in. Determine the lateral position of the molecule to be measured based on the midpoint of the double-helix spot. Obtain the axial position based on the angle between the centers of the two spots combined with the calibration result under the numerical aperture.

[0065] Specific implementation method five: Combination Figure 3 This embodiment is described. The double-helix spread function metalens-based three-dimensional microscopic imaging system includes an LED light source 1, a collimating lens 2, a first polarizer 3, a converging lens 4, a half-reflecting half-mirror 5, a first microscope objective 6, a sample stage 7, a first tube lens 8, a metalens 9, a second microscope objective 10, a second polarizer 11, a second tube lens 12, and a CMOS camera 13.

[0066] The LED light source 1, the collimating lens 2, the first polarizer 3 and the converging lens 4 are arranged in sequence from left to right on one side of the half-reflecting half-mirror 5, the sample stage 7 and the first microscope objective lens 6 are arranged in sequence from top to bottom above the half-reflecting half-mirror 5, and the first tube lens 8, the meta-lens 9, the second microscope objective lens 10, the second polarizer 11, the second tube lens 12 and the CMOS camera 13 are arranged in sequence from top to bottom below the half-reflecting half-mirror 5.

[0067] In this embodiment, the wavelength of the LED light source 1 can be any wavelength in the visible light band of 400nm-650nm, and the emitted light passes through the collimating lens to produce a parallel beam with good collimation;

[0068] Metalens 6 can independently control multiple polarization states and produce continuously rotating double-helix light spots under different polarization incidence conditions. The rotation center is located at different axial depths, thus achieving periodic connection. The axial detection range of the three-polarization-state double-helix point spread metalens is greater than that of a single polarization state.

[0069] Secondary imaging is performed using a microscope objective lens placed after the meta-lens. The microscope objective lens can be a commercial objective lens and used in conjunction with the tube lens.

[0070] Specific implementation method six: combination Figure 3 This embodiment describes the method for three-dimensional microscopic imaging based on a double-helix point spread function metalens, including the following steps:

[0071] Step 1: An LED light source 1 arranged along the direction of light beam propagation emits a divergent light beam with poor coherence, which is converted into parallel light by a collimating lens 2. The collimated light passes through a first polarizer 3 to produce corresponding polarized light, which is converged by a converging lens 4 onto the rear focal plane of a first microscope objective 6. The first microscope objective 6 has a numerical aperture that matches the size of the details to be resolved on the sample on the sample stage 7, and can evenly project the light beam processed by the half-reflecting half-mirror 5 onto the sample to be inspected;

[0072] Step 2: The first microscope objective lens 6 collects the light reflected by the sample to be tested, and the light is focused by the first tube lens 8 after passing through the half-reflecting half-mirror lens 5. The focused light is modulated by the multi-polarization double-helix point spread function through the meta-lens 9. The modulated image is polarized by the second polarizer 11, and the microscopic system composed of the second microscope objective lens 10 and the second tube lens 12 is used for secondary imaging, and is collected by the CMOS camera 13.

[0073] Step 3: Decode the acquired double-helix point spread function modulation image. Use the polarization state and the distance between the two spots to determine which repeat the spot is in. Determine the lateral position of the molecule to be measured based on the midpoint of the double-helix spot. Obtain the axial position based on the angle between the centers of the two spots combined with the calibration result under the numerical aperture.

[0074] Specific implementation method seven: combination Figure 2 and Figure 3 This embodiment describes the relationship between the focal lengths f1, f2, and f3 of the metalens in different polarization states and the object distance a and image distance b of the double-helix point spread function metalens three-dimensional microscopic imaging system according to this embodiment satisfies the Gaussian formula:

[0075] How it works

[0076] Based on the traditional 3D point spread function imaging method, the present invention uses an integrated meta-lens to generate multi-polarization state double-helix point spread function modulation, avoiding the influence of the zero-order diffraction spot. A polarization-multiplexed multi-polarization state double-helix meta-lens is designed to achieve coaxial and multi-period connection imaging with different polarization states of incident light, improving energy utilization and imaging range, and enhancing the integration and lightweighting of the system. By combining the characteristics of the multi-polarization state 3D point spread function with the advantages of the metasurface, the system can be imaged over a large range with high precision while reducing the complexity of the system, making the system easier to integrate and meeting the needs of current 3D detection systems.

[0077] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement of the above embodiments made according to the technical essence of the present invention, within the spirit and principles of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A three-dimensional microscopic imaging method based on a double-helix point spread function metalens, characterized by: The steps of the double-helix point spread function metalens three-dimensional microscopic imaging method include: S100. Designing and processing a metalens having multi-polarization state double-helix point spread function characteristics by simulation, wherein the metalens periodically arranges basic unit structures to form a complete metalens based on the double-helix point spread function phase and lens phase distribution through geometric phase and propagation phase arrangement methods; S200: Build an optical system with a meta-lens as the core to perform multi-polarization double-helix point spread function modulation. Use the meta-lens to image the molecules to be measured, change the different polarization states of the incident light, and obtain multiple double-helix images. S300. Determine which repeat the light spot is in based on the dual basis of the polarization state and the distance between the two light spots. Determine the lateral position of the molecule to be measured based on the midpoint of the double helix light spot. Obtain the axial position based on the angle between the centers of the two light spots combined with the numerical aperture calibration result.

2. A three-dimensional microscopic imaging system based on a double-helix point spread function metalens, characterized by: The meta-lens is based on the double-helix point spread function phase and lens phase distribution, and periodically arranges the basic unit structure through the geometric phase and propagation phase arrangement method to form a complete meta-lens. The three-dimensional microscopic imaging system based on the double-helix point spread function meta-lens includes an illumination module, a sample stage (5) and an imaging module; the illumination module is arranged on one side of the sample stage (5), and the imaging module is arranged on the other side of the sample stage (5); the illumination module includes an LED light source (1), a collimating lens (2), a first polarizer (3) and a converging lens (4), the LED light source (1), the collimating lens (2), the first polarizer (3) and the converging lens (4) ) and a converging lens (4) are sequentially arranged from left to right; the imaging module comprises a meta-lens (6), a microscope objective lens (7), a second polarizer (8), a tube lens (9) and a CMOS camera (10); the meta-lens (6), the microscope objective lens (7), the second polarizer (8), the tube lens (9) and the CMOS camera (10) are sequentially arranged from left to right, and the collected double-helix point spread function modulated image is solved, and the location of the light spot in the repetition is determined based on the dual basis of the polarization state and the distance between the two light spots, and the lateral position of the molecule to be measured is determined based on the midpoint of the double-helix light spot, and the axial position is obtained based on the angle between the centers of the two light spots combined with the calibration result under the numerical aperture.

3. An imaging method for a 3D microscopic imaging system based on a double-helix point spread function metalens according to claim 2, characterized in that: The steps of the double-helix point spread function metalens three-dimensional microscopic imaging method include: Step 1: An LED light source (1) arranged along the propagation direction of the light beam emits a divergent light beam with poor coherence, which is converted into parallel light by a collimating lens (2). The collimated light passes through a first polarizer (3) to generate corresponding polarized light, which is converged on the sample to be tested by a converging lens (4). The sample is placed on a sample stage (5); Step 2: Light passing through the sample passes through the meta-lens (6) to achieve multi-polarization state double-helix point spread function modulation. The modulated image is polarized by the second polarizer (8), and is imaged again by the microscope system consisting of the microscope objective lens (7) and the tube lens (9), and is collected by the CMOS camera (10); Step 3: Decode the acquired double-helix point spread function modulation image. Use the polarization state and the distance between the two spots to determine which repeat the spot is in. Determine the lateral position of the molecule to be measured based on the midpoint of the double-helix spot. Obtain the axial position based on the angle between the centers of the two spots combined with the numerical aperture calibration result.

4. A three-dimensional microscopic imaging system based on a double-helix point spread function metalens, characterized by: The meta-lens is arranged according to the phase of the double helix point spread function and the lens phase distribution, and the basic unit structure is periodically arranged through the geometric phase and propagation phase arrangement method to form a complete meta-lens. The three-dimensional microscopic imaging system based on the double helix point spread function meta-lens includes an LED light source (1), a collimating lens (2), a first polarizer (3), a converging lens (4), a half-reflective half-mirror (5), a first microscope objective (6), a sample stage (7), a first tube lens (8), a meta-lens (9), a second microscope objective (10), a second polarizer (11), a second tube lens (12) and a CMOS camera (13); The LED light source (1), the collimating lens (2), the first polarizer (3) and the converging lens (4) are sequentially arranged on one side of the half-reflecting half-mirror (5) from left to right, the sample stage (7) and the first microscope objective lens (6) are sequentially arranged above the half-reflecting half-mirror (5) from top to bottom, the first tube lens (8), the meta-lens (9), the second microscope objective lens (10), the second polarizer (11), the second tube lens (12) and the CMOS camera (13) are sequentially arranged below the half-reflecting half-mirror (5) from top to bottom, the collected double-helix point spread function modulated image is solved, and the polarization state and the distance between the two spots are used to determine which repeat the spot is in. The lateral position of the molecule to be measured is determined according to the midpoint of the double-helix spot, and the axial position is obtained according to the angle between the centers of the two spots combined with the calibration result under the numerical aperture.

5. An imaging method using the double-helix point spread function metalens 3D microscopic imaging system according to claim 4, characterized in that: The steps of the double-helix point spread function metalens three-dimensional microscopic imaging method include: Step 1: An LED light source (1) arranged along the propagation direction of the light beam emits a divergent light beam with poor coherence, which is formed into parallel light through a collimating lens (2). The collimated light passes through a first polarizer (3) to generate corresponding polarized light, which is converged on the rear focal plane of a first microscope objective lens (6) through a converging lens (4). The first microscope objective lens (6) has a numerical aperture that matches the size of the details to be resolved on the sample on the sample stage (7), and can evenly project the light beam processed by the half-reflecting half-mirror lens (5) onto the sample to be inspected; Step 2: The first microscope objective lens (6) collects the light reflected by the sample to be inspected, and focuses the light through the half-reflecting half-mirror lens (5) by the first tube lens (8). The focused light is modulated by the multi-polarization double-helix point spread function through the meta-lens (9). The modulated image is polarized by the second polarizer (11), and is subjected to secondary imaging by the microscope system composed of the second microscope objective lens (10) and the second tube lens (12), and is collected by the CMOS camera (13). Step 3: Decode the acquired double-helix point spread function modulation image. Use the polarization state and the distance between the two spots to determine which repeat the spot is in. Determine the lateral position of the molecule to be measured based on the midpoint of the double-helix spot. Obtain the axial position based on the angle between the centers of the two spots combined with the numerical aperture calibration result.

6. The double-helix point spread function metalens 3D microscopic imaging system according to claim 2 or 4, characterized in that: Focal length of metalens under different polarization states , , Distance to object a and image distance b The relationship between them satisfies Gauss's formula .

Images