Method and device for improving SPP microscopic imaging resolution and medium

Abstract

The invention provides a method, a system, equipment and a medium for improving SPP microscopic imaging resolution, and the method comprises the steps: carrying out the annular shaping of light emitted by a light source through a conical lens combination, obtaining a collimated annular light spot, and focusing the collimated annular light spot to a rear focal plane of an objective lens; the collimated annular light spot is obliquely incident to a metal-substrate interface of an excitation chip in an annular wide-field plane wave mode, the incident angle is adjusted to be an SPP excitation angle, Bessel SPP is excited on the surface of a gold film of the excitation chip, and the Bessel SPP is spread along the surface of the gold film and is scattered with a nano substance; sPP scattering is converted into an optical signal, the optical signal and reflected light are collected by an objective lens together, transmitted to a far field through a leaky mode radiation effect and imaged in a CCD camera, so that the problems that the SPRM imaging spatial resolution is low due to anisotropic transmission during one-way SPP excitation, and the SPRM real-time rapid imaging is affected due to switching of the SPP excitation direction through a mechanical device are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of surface plasmon microscopy, and in particular to a method, device, equipment and medium for improving the resolution of SPP microscopy. Background Art

[0002] In modern scientific research and technological applications, high-resolution microscopic imaging technology has always been a vital tool. Due to the limitation of the diffraction limit of light, the resolution of traditional optical microscopic imaging technology is usually around a few hundred nanometers, which is difficult to meet the needs of more detailed observations of the microscopic world. Surface plasmon resonance microscopy (SPRM) technology is a technology that uses the nanoscale field enhancement and leaky mode radiation effect of surface plasmons (SPP) to achieve high-sensitivity, label-free, non-destructive, and fast far-field imaging of nano-objects. Because of its enhancement of weak signals, it can achieve nanometer or even sub-nanometer sensitivity. SPRM has been used in label-free imaging studies of single viruses, exosomes, nanoparticles, cells, etc., and has broad application prospects in biomedical imaging, materials science, nanotechnology and other fields.

[0003] SPP (Surface Plasmon Polaritons) is a special electromagnetic mode propagating on the interface between metal and medium, which provides a new way to break through the optical diffraction limit and achieve high-resolution microscopic imaging. SPP has a unique property that can limit the light field to the nanoscale, so that microscopic imaging technology based on SPP can achieve a resolution far below the diffraction limit. SPRM uses a Kretschmann structure excited by parallel light. When the incident angle meets the wave vector matching condition, SPP is excited to achieve wide-field imaging. When nanoparticles are placed in the SPP action area, the SPP scattering caused by the particles interacts with the transmitted SPP to produce interference, forming an interference pattern with parabolic concentric fringes, which is transmitted to the far-field imaging through the leaky mode radiation effect, forming a unique U-shaped point spread function. Unlike the isotropic "Airy disk" point spread function of optical microscopes, SPP has an anisotropic transmission length, which reduces the spatial resolution, resulting in the degradation of imaging resolution in the SPP transmission direction, forming anisotropic spatial resolution. In order to improve the problem of poor resolution of SPRM, some researchers proposed a dual-channel switching SPRM, which switches dual-channel illumination in a direction symmetrical to the incident light, reconstructs a symmetrical point spread function, and improves spatial resolution; other researchers proposed a multi-directional scanning excitation method, which sequentially excites SPP at multiple azimuth angles, and after stitching multi-directional collected images, a high-resolution SPRM image can be obtained. However, the various improvement methods tried by researchers still have bottlenecks such as complex optical devices and poor resolution improvement effects.

[0004] In the prior art, dual-channel or multi-directional scanning is used to excite SPP. Through symmetrical excitation, the anisotropy of SPP transmission length is offset to achieve improved resolution. However, such methods require a mechanical device to switch the excitation direction and perform multi-directional scanning, which is time-consuming and affects the advantage of SPRM's real-time and fast imaging.

[0005] Therefore, it is urgent to propose a method to improve the resolution of SPP microscopic imaging to solve the technical problems of long mechanical scanning time, the need to switch the excitation direction, and the impact on SPRM real-time and rapid imaging. Summary of the invention

[0006] In order to overcome the problems existing in the related art, the present disclosure provides a method, device, equipment and medium for improving the resolution of SPP microscopic imaging, so as to solve the technical problems in the related art that anisotropic transmission during unidirectional SPP excitation leads to low spatial resolution of SPRM imaging and switching the Bessel SPP excitation direction by mechanical means affects the real-time and rapid imaging of SPRM.

[0007] One or more embodiments of this specification provide a method for improving the resolution of SPP microscopic imaging, comprising the following steps:

[0008] The light emitted by the light source is annularly shaped by the axon lens combination to obtain a collimated annular light spot, and the collimated annular light spot is focused on the back focal plane of the objective lens;

[0009] The collimated annular light spot is incident obliquely on the metal-substrate interface of the excitation chip in the form of an annular wide-field plane wave, and the incident angle is adjusted to be the SPP excitation angle, and the Bessel SPP is excited on the gold film surface of the excitation chip. The Bessel SPP propagates along the gold film surface and is scattered by the nanomaterial.

[0010] The Bessel SPP scattering is converted into a light signal and is collected by the objective lens together with the reflected light, transmitted to the far field through the leaky mode radiation effect, and imaged in the CCD camera.

[0011] Preferably, the light emitted by the light source is annularly shaped by a combination of conical lenses to obtain a collimated annular light spot, which specifically includes the following steps:

[0012] After the light emitted by the light source passes through the beam expander, the incident light beam is annularly shaped by the aconic lens combination;

[0013] The axicon assembly comprises a first axicon, a lens, and a second axicon, wherein the first axicon and the second axicon are two identical axicon lenses;

[0014] Specifically:

[0015] A first aconic lens is placed between the beam expander and the lens to convert the incident light into an annular light spot;

[0016] A second axicon is placed between the lens and the pellicle beam splitter to convert the annular light spot into a collimated annular light spot.

[0017] Preferably, in the axicon combination, the distance relationship between the first axicon, the second axicon and the lens satisfies the following formula:

[0018]

[0019] Among them, t c represents the center thickness of the axon, d represents the spot radius of the incident light beam of the axon combination, α represents the physical base angle of the axon, β represents the deflection angle between the refracted light and the optical axis, and n represents the refractive index of the axon.

[0020] Preferably, the adjusting the incident angle to be the SPP excitation angle specifically comprises the following steps:

[0021] The incident angle is adjusted to the SPP excitation angle by moving the position of the second axicon to adjust the radius of the annular spot on the back focal plane of the objective lens.

[0022] Preferably, before the light emitted by the light source is annularly shaped by the conical lens combination, the following steps are also included:

[0023] The light emitted by the light source is converted into radially polarized light by a radial polarizer, which excites SPPs from all azimuth angles.

[0024] Preferably, the exciting Bessel SPP on the gold film surface of the excitation chip further comprises the following steps:

[0025] The SPP is excited based on the Kretschmann structure coupled to the objective lens, and the objective lens is an oil immersion objective lens with a high numerical aperture.

[0026] Preferably, the excitation chip is fixed on a three-dimensional translation stage, and the imaging area on the surface of the gold film is changed by moving the translation stage.

[0027] One or more embodiments of this specification provide a device for improving the resolution of SPP microscopic imaging, including a shaping module, an excitation module, and an imaging module;

[0028] The shaping module is used to shape the light emitted by the light source into a collimated annular light spot after annular shaping through a combination of aconic lenses, and the collimated annular light spot is focused on the rear focal plane of the objective lens;

[0029] The excitation module is used to obliquely incident the collimated annular light spot on the metal-substrate interface of the excitation chip in the form of an annular wide-field plane wave, adjust the incident angle to be the SPP excitation angle, and excite Bessel SPP on the gold film surface of the excitation chip. The Bessel SPP propagates along the gold film surface and scatters with the nanomaterial;

[0030] The imaging module is used to convert the Bessel SPP scattering into an optical signal which is collected together with the reflected light by the objective lens and transmitted to the far-field imaging through the leaky mode radiation effect.

[0031] One or more embodiments of the present specification provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method for improving the resolution of SPP microscopic imaging as described above when executing the computer program.

[0032] One or more embodiments of the present specification provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the method for improving the resolution of SPP microscopic imaging as described above.

[0033] The present invention provides a method, device, equipment and medium for improving the resolution of SPP microscopic imaging, which has the advantages that the light emitted by the light source is annularly shaped by a cone lens combination to obtain a collimated annular light spot, and the collimated annular light spot is focused on the back focal plane of the objective lens, and the annular light spot can be obtained by the cone lens combination, and the incident angles of the light spots incident on the metal-substrate interface are the same, but the incident directions are different, so as to realize symmetrical multi-directional excitation; the collimated annular light spot is obliquely incident on the metal-substrate interface of the excitation chip in the form of an annular wide-field plane wave, and the incident angle is adjusted to the SPP excitation angle, and the incident angle is adjusted to the SPP excitation angle at the excitation chip. The gold film surface excites Bessel SPPs, which propagate along the gold film surface and scatter with the nanomaterial to achieve a symmetrical point spread function. Under the condition of ensuring low cost, no excitation scanning is required, and symmetrically excited Bessel SPPs can be achieved in a single imaging, thereby improving the spatial resolution of SPP imaging. The Bessel SPP scattering is converted into a light signal and is collected by the objective lens together with the reflected light, which is transmitted to the far field through the leaky mode radiation effect and imaged in a CCD camera, thereby obtaining single nanoparticle imaging with improved imaging resolution, and maintaining a large imaging field of view to ensure detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate one or more embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0035] Figure 1 A schematic flow chart of a method for improving SPP microscopic imaging resolution provided in one or more embodiments of this specification;

[0036] Figure 2 A schematic diagram of a circular radially polarized light excitation SPP microscopic imaging device provided in one or more embodiments of this specification, Figure 2 (a) is the theoretical model of the Bessel SPP microscopic imaging device and the excitation chip cross section. Figure 2 (b) is the formation of Bessel SPP interference imaging of particles on the excitation chip interface. Figure 2 (c) is a schematic diagram of the rear focal plane of the objective lens;

[0037] Figure 3 A schematic diagram of the structure of an aconic lens assembly provided in one or more embodiments of this specification;

[0038] Figure 4 A schematic diagram showing the effect of linear polarization and radial polarization excitation on the SPP absorption ring provided in one or more embodiments of this specification, Figure 4 (a) is linear polarization excitation, Figure 4 (b) is radial polarization excitation;

[0039] Figure 5 A schematic diagram of a device for improving SPP microscopic imaging resolution provided by one or more embodiments of this specification;

[0040] Figure 6 A schematic diagram of the structure of a computer device provided for one or more embodiments of this specification. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below in conjunction with the drawings in one or more embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the protection scope of the present invention.

[0042] The present invention is described in detail below in conjunction with specific implementation methods and the accompanying drawings.

[0043] Method Embodiment

[0044] According to an embodiment of the present invention, a method for improving the resolution of SPP microscopic imaging is provided, such as Figure 1 FIG. 2 is a flow chart of a method for improving the resolution of SPP microscopic imaging provided in this embodiment. The method for improving the resolution of SPP microscopic imaging according to an embodiment of the present invention comprises the following steps:

[0045] S110, the light emitted by the light source is annularly shaped by the cone lens combination to obtain a collimated annular light spot, and the collimated annular light spot is focused to the back focal plane of the objective lens, such as Figure 2 FIG. 1 is a schematic diagram of a Bessel SPP microscopic imaging device for annular radially polarized light excitation provided in this embodiment. Figure 2 (a) is the theoretical model of the Bessel SPP microscopic imaging device and the excitation chip cross section. Figure 2 (b) is the formation of Bessel SPP interference imaging of particles on the excitation chip interface. Figure 2 (c) is a schematic diagram of the rear focal plane of the objective lens. Based on the optical elements of the unidirectional excitation Bessel SPP experimental platform, an optical element group that generates an annular light spot - a cone lens combination is added behind the beam expander to perform annular shaping on the incident light beam to obtain a collimated annular light spot, and finally the collimated annular light spot is focused to the rear focal plane of the objective lens.

[0046] S120, the collimated annular light spot is incident obliquely on the metal-substrate interface of the excitation chip in the form of annular wide-field plane wave. The excitation chip is a glass sheet coated with a 50nm thick gold film. The excitation chip is fixed on a three-dimensional translation stage. The imaging area of ​​the immersion surface can be changed by moving the translation stage to find and observe the imaging target.

[0047] The incident angle of the radially polarized annular light spot is adjusted to the SPP excitation angle, and the Bessel SPP is excited on the gold film surface of the excitation chip. The Bessel SPP propagates radially along the gold film surface and is scattered by the nanomaterial. The incident angle of the light spot incident on the metal-substrate interface is the same, but the incident direction is different. The symmetrical multi-directional excitation makes the SPP propagate in multiple directions, thereby realizing a symmetrical point spread function and improving the spatial resolution of SPP imaging.

[0048] S130 and Bessel SPP scattering are converted into optical signals and collected by the objective lens together with the reflected light, transmitted to the far field through the leaky mode radiation effect, and collected in the CCD camera for imaging.

[0049] In the method provided in this embodiment, the light emitted by the light source is annularly shaped by a combination of aconical lenses to obtain a collimated annular light spot, and the collimated annular light spot is focused on the back focal plane of the objective lens. The annular light spot can be obtained by the combination of aconical lenses, and the incident angles of the light spots incident on the metal-substrate interface are the same, but the incident directions are different, so as to realize symmetrical multi-directional excitation; the collimated annular light spot is obliquely incident on the metal-substrate interface of the excitation chip in the form of an annular wide-field plane wave, and the incident angle is adjusted to be the SPP excitation angle, and Bessel SPP is excited on the gold film surface of the excitation chip, and the Bessel SPP propagates radially along the gold film surface and scatters with the nanomaterial to realize a symmetrical point spread function, and under the condition of ensuring low cost, no excitation scanning is required, and symmetrical excitation of SPP can be realized by single imaging, thereby improving the spatial resolution of SPP imaging; the Bessel SPP scattering is converted into a light signal and collected by the objective lens together with the reflected light, and transmitted to the far field through the leaky mode radiation effect, and imaged in the CCD camera, so as to obtain single nanoparticle imaging with improved imaging resolution, and a large imaging field of view can be maintained to ensure detection efficiency.

[0050] In one embodiment, light emitted by a light source is annularly shaped by a combination of aconic lenses to obtain a collimated annular light spot, which specifically includes the following steps:

[0051] HeNe laser is used as the excitation light source. The laser light source passes through a TM linear polarizer to change the polarization direction of the laser. The light emitted by the light source is expanded and collimated by a beam expander, and then the incident light beam is annularly shaped by a combination of conical lenses.

[0052] The axicon combination includes a first axicon, a lens, and a second axicon. The first axicon and the second axicon are two identical axicon lenses. Specifically:

[0053] A first axicon is placed between the beam expander and the lens to convert the incident light into a ring-shaped spot.

[0054] A second axicon is placed between the lens and the pellicle beam splitter to transform the annular spot into a collimated annular spot.

[0055] The method provided in this embodiment converts the laser beam into an annular spot through a combination of aconical lenses, which can provide enhanced field distribution. At the same time, radial polarization reduces the interference of TE polarized light that does not contribute to excitation, thereby improving imaging quality.

[0056] In one embodiment, unlike the single-path excitation, which adjusts the excitation angle by a one-dimensional displacement platform, the annular spot can achieve the SPP excitation angle by adjusting the annular light radius of the back focal plane to the SPP wave vector. Therefore, the distance between the first axicon, the second axicon and the lens is crucial. Figure 3 , which is a schematic structural diagram of the axon lens combination provided in this embodiment.

[0057] In the axicon combination, the distance relationship between the first axicon, the second axicon and the lens satisfies the following formula:

[0058]

[0059] Among them, t c represents the center thickness of the axon, d represents the spot radius of the incident light beam of the axon combination, α represents the physical base angle of the axon, β represents the deflection angle between the refracted light and the optical axis, and n represents the refractive index of the axon.

[0060] The first axicon converts the incident light into a beam with Bessel intensity distribution. The plane parallel to the axicon at the center of this diffraction-free zone is called the center plane of the diffraction-free zone. When the lens plane coincides with the center plane of the diffraction-free zone of the first axicon, the outgoing annular light spot is no longer parallel light. The second axicon has the same physical bottom angle as the first axicon, and its function is to collimate the focused annular light spot.

[0061] The incident angle is adjusted to the SPP excitation angle by moving the position of the second conic lens to adjust the radius of the annular spot on the rear focal plane of the objective lens. We observe the relationship between the annular spot and the SPP wave vector by imaging the rear focal plane of the objective lens, and the second moving conic lens adjusts the radius of the focusing ring. When the radius of the focusing annular spot coincides with the SPP wave vector, the Bessel SPP excitation effect is optimal.

[0062] The method provided in this embodiment realizes specific annular shaping and focusing of the laser beam through an axon-lens-axon combination, and then realizes the excitation of Bessel SPP by adjusting the matching of the annular beam and the SPP excitation angle.

[0063] In one embodiment, before the light emitted by the light source is annularly shaped by the axon lens combination, the following steps are also included:

[0064] The light emitted by the light source is converted into radially polarized light by a radial polarizer, which excites SPP from all azimuth angles. SPP is polarization-dependent, and usually only TM linearly polarized light can effectively excite SPP. Compared with traditional linearly polarized light excitation, the polarization characteristics of the radially polarized light we use have radial symmetry, so that it meets the TM linear polarization excitation conditions of SPP at 360°. Figure 4 As shown, it is a schematic diagram of the effect of linear polarization and radial polarization excitation on the SPP absorption ring provided in this embodiment. Figure 4 (a) is linear polarization excitation, Figure 4 (b) is radial polarization excitation, where Figure 4 In (a), the plasmon resonance of TM linearly polarized light occurs in the x direction, and is excited by TE polarization in the longitudinal y direction, so SPP cannot be excited in the y direction. Figure 4 The radial polarization excitation shown in (b) makes the plasmon resonance excitation distributed along all azimuth angles, reducing the interference of TE polarized light that does not contribute to the excitation, producing a strong local field enhancement effect and improving the image quality.

[0065] In one embodiment, exciting Bessel SPP on the gold film surface of the excitation chip further includes the following steps:

[0066] The Kretschmann structure based on the objective lens coupling excites SPP. The objective lens is a high numerical aperture oil immersion lens. The surface of the objective lens is immersed in a layer of refractive index matching oil. The incident light passes through the objective lens and the oil immersion layer and is incident on the gold substrate interface. Figure 2 As shown in (b), the wave vector at the glass-gold interface is k x , the wave vector that excites SPP at the gold-medium interface is k spp , according to the wave vector matching condition:

[0067]

[0068] Among them, λ0 represents the wavelength of the incident light, θ represents the angle of incidence, n1 represents the substrate refractive index, and n s represents the refractive index of the medium, ε m represents the real part of the complex dielectric constant of the gold film. By adjusting the incident angle θ, wave vector matching is achieved and SPP is excited at the gold-medium interface.

[0069] Device Embodiment

[0070] According to an embodiment of the present invention, a device for improving the resolution of SPP microscopic imaging is provided, such as Figure 5 , which is a schematic diagram of the structure of the device for improving the SPP microscopic imaging resolution provided in this embodiment. The device for improving the SPP microscopic imaging resolution according to the embodiment of the present invention includes a shaping module 51, an excitation module 52 and an imaging module 53.

[0071] The shaping module 51 is used for shaping the light emitted by the light source into a collimated annular light spot after the light is annularly shaped by the combination of aconic lenses, and the collimated annular light spot is focused on the rear focal plane of the objective lens.

[0072] The excitation module 52 is used to obliquely incident the collimated annular light spot on the metal-substrate interface of the excitation chip in the form of an annular wide-field plane wave, adjust the incident angle to the SPP excitation angle, and excite Bessel SPP on the gold film surface of the excitation chip. The Bessel SPP propagates along the gold film surface and scatters with the nanomaterial.

[0073] The imaging module 53 is used to convert the Bessel SPP scattering into an optical signal which is collected together with the reflected light by the objective lens and transmitted to the far-field imaging through the leaky mode radiation effect.

[0074] In the device provided in this embodiment, the light emitted by the shaping module 51 light source is annularly shaped by the conical lens combination to obtain a collimated annular light spot, and the collimated annular light spot is focused on the back focal plane of the objective lens. The annular light spot can be obtained by the conical lens combination, and the incident angle of the light spot incident on the metal-substrate interface is the same, but the incident direction is different, so as to realize symmetrical multi-directional excitation; the excitation module 52 obliquely incidents the collimated annular light spot on the metal-substrate interface of the excitation chip in the form of annular wide-field plane wave, adjusts the incident angle to the SPP excitation angle, and excites the Basset light on the gold film surface of the excitation chip. Bessel SPP and Bessel SPP propagate along the surface of the gold film and scatter with the nanomaterial to achieve a symmetrical point spread function. Under the condition of ensuring low cost, there is no need for excitation scanning, and a single imaging can achieve symmetrically excited Bessel SPP, thereby improving the spatial resolution of SPP imaging. The imaging module 53 converts the Bessel SPP scattering into a light signal which is collected together with the reflected light by the objective lens, and is transmitted to the far field through the leakage mode radiation effect, and is imaged in the CCD camera, so that single nanoparticle imaging with improved imaging resolution can be obtained, and a large imaging field of view can be maintained to ensure detection efficiency.

[0075] The embodiment of the present invention is an apparatus embodiment corresponding to the above-mentioned method embodiment. The specific operations of the processing steps of each module can be understood by referring to the description of the method embodiment, which will not be repeated here.

[0076] like Figure 6As shown, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which implements the method for improving the SPP microscopic imaging resolution in the above-mentioned embodiment when the computer program is executed by a processor, or implements the method for improving the SPP microscopic imaging resolution in the above-mentioned embodiment when the computer program is executed by a processor.

[0077] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0078] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The device and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and the contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A method for improving the resolution of SPP microscopic imaging, characterized in that: The following steps are involved: The light emitted by the light source is annularly shaped by the axon lens combination to obtain a collimated annular light spot, and the collimated annular light spot is focused on the back focal plane of the objective lens; The collimated annular light spot is incident obliquely on the metal-substrate interface of the excitation chip in the form of an annular wide-field plane wave, and the incident angle is adjusted to be the SPP excitation angle, and the Bessel SPP is excited on the gold film surface of the excitation chip. The Bessel SPP propagates along the gold film surface and is scattered by the nanomaterial. The Bessel SPP scattering is converted into a light signal and is collected by the objective lens together with the reflected light, transmitted to the far field through the leaky mode radiation effect, and imaged in the CCD camera.

2. The method for improving SPP microscopic imaging resolution according to claim 1, characterized in that: The light emitted by the light source is annularly shaped by a combination of aconic lenses to obtain a collimated annular light spot, which specifically includes the following steps: After the light emitted by the light source passes through the beam expander, the incident light beam is annularly shaped by the aconic lens combination; The axicon assembly comprises a first axicon, a lens, and a second axicon, wherein the first axicon and the second axicon are two identical axicon lenses; Specifically: A first aconic lens is placed between the beam expander and the lens to convert the incident light into an annular light spot; A second axicon is placed between the lens and the pellicle beam splitter to convert the annular light spot into a collimated annular light spot.

3. The method for improving SPP microscopic imaging resolution according to claim 1 or 2, characterized in that: In the axicon combination, the distance relationship between the first axicon, the second axicon and the lens satisfies the following formula: Among them, t c represents the center thickness of the axon, d represents the spot radius of the incident light beam of the axon combination, α represents the physical base angle of the axon, β represents the deflection angle between the refracted light and the optical axis, and n represents the refractive index of the axon.

4. The method for improving SPP microscopic imaging resolution according to claim 1, characterized in that: The adjusting the incident angle to the SPP excitation angle specifically includes the following steps: The incident angle is adjusted to the SPP excitation angle by moving the position of the second axicon to adjust the radius of the annular spot on the back focal plane of the objective lens.

5. The method for improving SPP microscopic imaging resolution according to claim 1, characterized in that: Before the light emitted by the light source is annularly shaped by the axon lens combination, the following steps are also included: The light emitted by the light source is converted into radially polarized light by a radial polarizer, which excites Bessel SPPs from all azimuth angles.

6. The method for improving SPP microscopic imaging resolution according to claim 1, characterized in that: The exciting Bessel SPP on the gold film surface of the excitation chip further comprises the following steps: The SPP is excited based on the Kretschmann structure coupled to the objective lens, and the objective lens is an oil immersion objective lens with a high numerical aperture.

7. The method for improving SPP microscopic imaging resolution according to claim 1, characterized in that: The excitation chip is fixed on a three-dimensional translation stage, and the imaging area on the surface of the gold film is changed by moving the translation stage.

8. A device for improving the resolution of SPP microscopic imaging, characterized in that: It includes shaping module, excitation module and imaging module; The shaping module is used to shape the light emitted by the light source into a collimated annular light spot after annular shaping through a combination of aconic lenses, and the collimated annular light spot is focused on the rear focal plane of the objective lens; The excitation module is used to obliquely incident the collimated annular light spot on the metal-substrate interface of the excitation chip in the form of an annular wide-field plane wave, adjust the incident angle to be the SPP excitation angle, and excite Bessel SPP on the gold film surface of the excitation chip. The Bessel SPP propagates along the gold film surface and scatters with the nanomaterial; The imaging module is used to convert the Bessel SPP scattering into an optical signal which is collected together with the reflected light by the objective lens and transmitted to the far-field imaging through the leaky mode radiation effect.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method for improving the resolution of SPP microscopic imaging according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for improving the resolution of SPP microscopic imaging according to any one of claims 1 to 7 are implemented.

Images