Plasmonic microscopy system

Abstract

This invention proposes a plasma microscopy imaging system, comprising an illumination device, a metal thin film assembly, a sample scanning stage, a microscopic imaging device, and a detection device. This invention excites plasma on a metal thin film using vortex-polarized light, causing the surface plasma centers to converge and obtain a sub-diffraction-limited excitation spot, achieving super-resolution optical imaging. The plasma microscopy imaging system of this invention uses single-beam illumination, resulting in a simple optical path; the sample is placed via the sample stage, eliminating the need for metal nanostructures and simplifying sample preparation; furthermore, this plasma microscopy imaging system exhibits a surface plasmon enhancement effect, providing sensitivity superior to general optical systems, achieving single-molecule detection levels; this plasma microscopy imaging system has no restrictions on fluorescent dyes and samples, and the system can be used for fluorescence signal imaging, Raman signal imaging, and other optical scattering signal imaging.

Description

Technical Field

[0001] This invention relates to the field of microscopic imaging technology, and more particularly to a plasma microscopic imaging system. Background Technology

[0002] This section provides only background information relevant to this disclosure and is not necessarily prior art.

[0003] Currently, approximately 80% of microscopic imaging research in life sciences still utilizes optical microscopes, meaning that advancements in life sciences have been intertwined with the development of optical microscopy. However, due to the diffraction limit, the spatial resolution of optical microscopes is restricted to about half a wavelength, severely hindering biologists' detailed studies of subcellular structures. To address this, various super-resolution optical microscopy techniques have been developed, such as stimulated emission depletion microscopy (STED), structured illumination microscopy (SIM), scanning near-field optical microscopy (SNOM), photo-activated localization microscopy (PALM), stochastic optical reconstruction microscopy (STORM), and tipped-enhanced Raman spectroscopy (TES). Each technique has its own advantages and disadvantages in optical imaging. For example, STED achieves extremely high optical resolution but requires extremely high light intensity, easily leading to photobleaching of fluorescent dyes, and has a complex optical path, requiring highly skilled operators. PALM and STORM offer high spatial resolution, but the fluorescent dyes must possess photoactivated properties, and complex post-processing is required. SIM, on the other hand, necessitates a complex optical system and post-processing. SNOM and TERS require a high degree of coordination between the probe and the optical path, making operation complex. Furthermore, the efficiency of SNOM fiber probes in transmitting excitation light is low, significantly limiting detection sensitivity. TERS probes and samples are easily burned out under highly focused, intense light. All of these factors hinder the widespread application of these technologies and make them difficult for non-specialists to operate.

[0004] Super-resolution optical imaging is achieved by using an optical field to excite plasma propagation and taking advantage of the short equivalent wavelength of plasma. To control the direction of plasma propagation, specially designed metal nanostructures, such as nanopores, nanospheres, nanogrooves, or even nanoarrays, are usually required. This makes sample preparation extremely complex and limits the application to specific wavelengths. Summary of the Invention

[0005] The objective of this invention is to at least address the technical problems of limited resolution and complex sample preparation in existing plasma microscopy. This objective is achieved through the following technical solution:

[0006] This invention proposes a plasma microscopy imaging system, comprising:

[0007] An illumination device for generating vortex-circularly polarized light;

[0008] A metal thin film assembly includes a metal thin film and a substrate, wherein one side of the metal thin film is attached to the substrate;

[0009] A sample scanning stage, which is used to place the sample and perform sample imaging scanning;

[0010] A microscopic imaging device is used to focus the vortex circularly polarized light into an empty shell-shaped excitation spot. The excitation spot excites the plasma of the metal thin film to form a sub-diffraction-limited plasma excitation spot. The plasma excitation spot is used to excite the sample on the sample scanning stage and emit signal light.

[0011] A detection device is used to filter out the excitation light and focus the signal light to form an image.

[0012] This invention excites plasma on a metal thin film using vortex-polarized light, causing the surface plasma centers to converge and obtain a sub-diffraction-limited excitation spot, thus achieving super-resolution optical imaging. The plasma microscopy system of this invention uses single-beam illumination, resulting in a simple optical path; samples are placed via a sample stage, eliminating the need for metal nanostructures and simplifying sample preparation; furthermore, this plasma microscopy system exhibits a surface plasmon enhancement effect, providing sensitivity superior to conventional optical systems and achieving single-molecule detection levels; this plasma microscopy system has no restrictions on fluorescent dyes or samples, and can be used for fluorescence signal imaging, Raman signal imaging, and other optical scattering signal imaging.

[0013] In addition, the plasma microscopy imaging system according to the present invention may also have the following additional technical features:

[0014] In some embodiments of the present invention, the lighting device includes an excitation laser, a polarizer, a waveplate, and a phase plate arranged sequentially along the optical path. The excitation laser generates laser light of a preset wavelength, the polarizer modulates the laser light emitted by the excitation laser into polarized light, the waveplate modulates the polarized light into circularly polarized light, and the phase plate modulates the circularly polarized light into vortex-polarized light.

[0015] In some embodiments of the present invention, the polarized light is linearly polarized light.

[0016] In some embodiments of the present invention, the waveplate is a quarter-waveplate.

[0017] In some embodiments of the present invention, the microscopic imaging device includes an excitation objective lens arranged sequentially along the optical path. The excitation objective lens receives the vortex circularly polarized light emitted by the illumination device and converges the vortex circularly polarized light to form the excitation spot on the metal thin film. The hollow spot excites surface plasma that converges at the center on the surface of the metal thin film and generates the sub-diffraction-limited plasma excitation spot.

[0018] In some embodiments of the present invention, the microscopic imaging device further includes a reflector disposed in the optical path between the illumination device and the excitation objective, the reflector being used to reflect the vortex circularly polarized light emitted by the illumination device to the excitation objective.

[0019] In some embodiments of the present invention, the sample scanning stage includes a sample carrying device and a position adjustment device. The sample carrying device is used to place the sample, and the position adjustment device is connected to the sample carrying device. The position adjustment device can adjust the position of the sample carrying device to adjust the scanning position of the sample.

[0020] In some embodiments of the present invention, the detection device includes a filter, a collecting lens, and an imaging camera arranged sequentially along the optical path. The filter can filter out the excitation light, the collecting lens can focus the signal light onto the imaging camera to form an image of the excitation focal spot, and the imaging camera converts the image of the excitation focal spot formed by the signal light into an electrical signal.

[0021] In some embodiments of the present invention, the imaging camera includes a photodetector and a host computer. The photodetector is used to collect the converging signal light from the collecting lens and send the collected light signal to the host computer. The host computer is used to generate a microscopic image corresponding to the sample based on the light signal.

[0022] In some embodiments of the present invention, the metal thin film is made of a precious metal, and the metal thin film is deposited on the substrate by means of a coating. Attached Figure Description

[0023] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0024] In the attached diagram:

[0025] Figure 1 A schematic diagram of the structure of a plasma microscopy imaging system according to an embodiment of the present invention is shown.

[0026] Figure 2 An image of a 40-nanometer diameter fluorescent particle is schematically shown using a plasma microscopy imaging system according to an embodiment of the present invention.

[0027] Figure 3 Fluorescence imaging of microtubules in HeLa cells using the plasma microscopy imaging system provided in this embodiment of the invention;

[0028] Figure 4 Raman scattering image of nanotubes provided by the plasma microscopy imaging system in an embodiment of the present invention.

[0029] The attached figures are labeled as follows:

[0030] 10: Illumination device; 11: Excitation laser; 12: Polarizer; 13: Waveplate; 14: Phase plate;

[0031] 20: Microscopic imaging device; 21: Reflecting mirror; 22: Excitation objective lens; 23: Metal thin film;

[0032] 30: Detection device; 31: Filter; 32: Collection lens; 33: Imaging camera. Detailed Implementation

[0033] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0034] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0035] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0036] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented as "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0037] like Figure 1 As shown, this invention proposes a plasma microscopy imaging system, comprising:

[0038] Illumination device 10 is used to generate vortex-circularly polarized light;

[0039] A metal thin film assembly includes a metal thin film 23 and a substrate, wherein one side of the metal thin film 23 is attached to the substrate;

[0040] The sample scanning stage (not shown in the figure) is used to place the sample and perform sample imaging scanning.

[0041] The microscopic imaging device 20 is used to focus vortex circularly polarized light into an empty shell-shaped excitation spot. The excitation spot excites the plasma of the metal thin film 23 to form a sub-diffraction-limited plasma excitation spot. The plasma excitation spot excites the sample emission signal light on the sample scanning stage.

[0042] The detection device 30 is used to filter out the excitation light and focus the signal light for imaging.

[0043] It is understood that the lighting device 10 may include a laser 11 to generate excitation light, which is then converted into circularly polarized light by a polarizer 12, a waveplate 13, and a phase plate 14 arranged along the optical path of the excitation light, and finally into vortex-polarized light. The polarizer 12 is a fundamental optical element whose function is to convert incident light of arbitrary polarization state into linearly polarized light. Linearly polarized light refers to light whose light vector vibrates in only one fixed direction along the direction of propagation, and the trajectory of the light vector endpoint is a straight line. The plane formed by the direction of the light vector and the direction of light propagation is called the vibration plane. The vibration plane of linearly polarized light is fixed and does not rotate. Most light sources do not emit linearly polarized light but emit natural light, requiring the polarizer 12 to obtain linearly polarized light. Circularly polarized light refers to light whose rotating electric vector endpoint traces a circular trajectory. When two plane-polarized lights with the same propagation direction, mutually perpendicular vibration directions, and a constant phase difference of φ = (2m ± 1 / 2)π are superimposed, they can synthesize circularly polarized light with a regularly changing electric vector. The magnitude of the electric vector of circularly polarized light remains constant, while its direction changes uniformly with time. Phase plate 14 can generate vortex light. When using phase plate 14 to generate vortex light, a linear polarizer 12 and a quarter-wave plate 13 must be placed in front to ensure that the light incident on phase plate 14 is circularly polarized.

[0044] The microscopic imaging device 20 can focus vortex circularly polarized light onto the focal plane to form a hollow-shell-shaped light spot by setting an excitation objective 22. The magnification, wavelength range, working distance, and numerical aperture of the excitation objective 22 can be set according to actual needs. The aforementioned focal plane is set on the surface of the metal thin film 23 to excite the surface plasma that converges at the center, generating a sub-diffraction-limited plasma excitation light spot. By utilizing the interaction between the surface plasma wave generated in the near-field region of the metal surface during surface plasma resonance and the sample under test, high-precision demodulation of the sample-related physical parameters can be achieved by detecting the emitted light wave information.

[0045] This invention excites plasma using vortex-circularly polarized light, achieving central convergence of surface plasma and obtaining a sub-diffraction-limited excitation spot for super-resolution optical imaging. The plasma microscopy system of this invention employs single-beam illumination, resulting in a simple optical path; sample placement via a sample stage eliminates the need for metal nanostructures, simplifying sample preparation; furthermore, this plasma microscopy system exhibits surface plasmon enhancement, providing sensitivity superior to conventional optical systems, achieving single-molecule detection levels; this plasma microscopy system has no limitations on fluorescent dyes or samples, and can be used for fluorescence signal imaging, Raman signal imaging, and other optical scattering signal imaging.

[0046] Figure 2 The left-hand image shows an image of a 40-nanometer diameter fluorescent particle imaged by a surface plasmon super-resolution microscopy system excited by vortex circularly polarized light provided in this embodiment of the invention. It can be approximated as the point spread function of the microscope in this embodiment of the invention. Figure 2 The contour plot on the right shows that the diameter of the principal maxima of the point spread function is 120 nm, which breaks through the optical diffraction limit of the 532 nm excitation light.

[0047] Figure 3 The image on the left shows a fluorescence image of microtubules in HeLa cells (a type of cervical cancer cell) obtained by a surface plasmon super-resolution microscopy system excited by vortex circularly polarized light, as provided in an embodiment of the present invention. Figure 3 The outline diagram on the right shows that the diameter of the microtube is approximately 170 nm, which breaks the optical diffraction limit of 532 nm excitation light.

[0048] Figure 4 The image on the left shows a Raman scattering image of a nanotube obtained by the vortex circularly polarized light-excited surface plasmon super-resolution microscopy imaging system provided in this embodiment of the invention. Figure 4 The outline diagram on the right shows that two carbon nanotubes with a spacing of 160 nanometers can be clearly distinguished, breaking the optical diffraction limit of 532 nanometers.

[0049] In some embodiments of the present invention, the lighting device 10 includes an excitation laser 11, a polarizer 12, a waveplate 13 and a phase plate 14 arranged sequentially along the optical path. The excitation laser 11 generates laser light of a preset wavelength, the polarizer 12 modulates the laser light emitted by the excitation laser 11 into polarized light, the waveplate 13 modulates the polarized light into circularly polarized light, and the phase plate 14 modulates the circularly polarized light into vortex circularly polarized light.

[0050] In some embodiments of the present invention, the polarized light is linearly polarized light. Linearly polarized light is light whose light vector endpoints trace a straight line, that is, the light vector vibrates only along a definite direction, and its magnitude changes with the phase but its direction remains unchanged.

[0051] In some embodiments of the present invention, waveplate 13 is a quarter-wave plate. Quarter-wave plates are commonly used in optical paths to convert linearly polarized light into circularly polarized or elliptically polarized light. When light of a certain wavelength is incident perpendicularly through quarter-wave plate 13, the incident linearly polarized light is emitted as circularly polarized or elliptically polarized light.

[0052] In some embodiments of the present invention, the microscopic imaging device 20 includes an excitation objective lens 22 arranged sequentially along the optical path. The excitation objective lens 22 receives vortex circularly polarized light emitted from the illumination device 10 and converges the vortex circularly polarized light to form an empty shell-shaped light spot on the metal thin film 23. The empty shell-shaped light spot excites surface plasma that converges at the center on the surface of the metal thin film 23 and generates a sub-diffraction-limited plasma excitation light spot.

[0053] In some embodiments of the present invention, the microscopic imaging apparatus 20 further includes a reflector 21, which is disposed in the optical path between the illumination device 10 and the excitation objective lens 22. The reflector 21 is used to reflect the vortex circularly polarized light emitted by the illumination device 10 to the excitation objective lens 22. By providing a reflector, the direction and angle of the optical path can be adjusted, making the microscopic imaging apparatus 20 more adaptable.

[0054] In some embodiments of the present invention, the sample scanning stage includes a sample carrying device and a position adjustment device. The sample carrying device is used to place the sample, and the position adjustment device is connected to the sample carrying device. The position adjustment device can adjust the position of the sample carrying device to adjust the scanning position of the sample.

[0055] Specifically, the sample carrying device can be configured with the sample stage structure according to the type of sample, and the specific configuration is not limited. The sample adjustment device has the ability to move and adjust, and the direction can be adjusted through a linear displacement mechanism. During sample scanning, the computer controls the position adjustment device to move the focus along the sample to achieve a complete scan and detection of the sample.

[0056] In some embodiments of the present invention, the detection device 30 includes a filter 31, a collecting lens 32 and an imaging camera 33 arranged sequentially along the optical path. The filter 31 can filter out the excitation light, the collecting lens 32 can focus the signal light onto the imaging camera 33 to generate an image of the excitation focal spot, and the imaging camera 33 converts the image of the excitation focal spot formed by the signal light into an electrical signal.

[0057] Understandably, filter 13 is configured to filter the excitation light to remove excess excitation light and prevent it from interfering with the signal light received by the subsequent photodetector. The collecting lens 32 focuses the signal light onto the imaging camera 33 so that the imaging camera 33 can receive the light signal.

[0058] In some embodiments of the present invention, the imaging camera 33 includes a photodetector and a host computer. The photodetector is used to collect the converging signal light from the lens 32, convert the collected light signal into an electrical signal and send it to the host computer. The host computer is used to generate a microscopic image corresponding to the sample based on the electrical signal.

[0059] Specifically, the photodetector can be a CCD (Charge Coupled Device) image sensor, which uses photodiodes for photoelectric conversion to convert the image into digital data, or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, depending on the actual needs. The host computer can be a computer that receives the electrical signals from the photodetector and converts them into visual graphics or charts.

[0060] In some embodiments of the present invention, the metal thin film 23 is made of gold or silver, and the metal thin film 23 is deposited on the substrate by means of a coating.

[0061] The substrate is either ordinary glass or plastic substrate, and the substrate is set as a glass slide. A thin film of gold or silver with a thickness of nanometers is deposited on the glass slide.

[0062] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A plasma microscopic imaging system, characterized in that, include: An illumination device for generating vortex-polarized light; A metal thin film assembly includes a metal thin film and a substrate, wherein one side of the metal thin film is attached to the surface of the substrate; A sample scanning stage, which is used to place the sample and perform sample imaging scanning; A microscopic imaging device is used to focus the vortex circularly polarized light into an empty shell-shaped excitation spot. The excitation spot excites the plasma of the metal thin film to form a sub-diffraction-limited plasma excitation spot. The plasma excitation spot is used to excite the sample on the sample scanning stage and emit signal light. A detection device is used to filter out the excitation light and focus the signal light into an image; The lighting device includes an excitation laser, a polarizer, a waveplate, and a phase plate arranged sequentially along the optical path. The excitation laser generates laser light of a preset wavelength. The polarizer modulates the laser light emitted by the excitation laser into polarized light. The waveplate modulates the polarized light into circularly polarized light. The phase plate modulates the circularly polarized light into vortex-polarized light. The microscopic imaging device includes excitation objective lenses arranged sequentially along the optical path. The excitation objective lenses receive the vortex circularly polarized light emitted by the illumination device and converge the vortex circularly polarized light to form the excitation spot on the metal thin film. The hollow spot excites surface plasma that converges at the center on the surface of the metal thin film and generates the sub-diffraction-limited plasma excitation spot.

2. The plasma microscopy imaging system according to claim 1, characterized in that, The polarized light is linearly polarized.

3. The plasma microscopy imaging system according to claim 1, characterized in that, The waveplate is a quarter-wave plate.

4. The plasma microscopy imaging system according to claim 1, characterized in that, The microscopic imaging device further includes a reflector disposed in the optical path between the illumination device and the excitation objective lens. The reflector is used to reflect the vortex circularly polarized light emitted by the illumination device to the excitation objective lens.

5. The plasma microscopy imaging system according to claim 1, characterized in that, The sample scanning stage includes a sample carrier and a position adjustment device. The sample carrier is used to place the sample, and the position adjustment device is connected to the sample carrier. The position adjustment device can adjust the position of the sample carrier to adjust the scanning position of the sample.

6. The plasma microscopy imaging system according to claim 1, characterized in that, The detection device includes a filter, a collecting lens, and an imaging camera arranged sequentially along the optical path. The filter can filter out the excitation light, the collecting lens can focus the signal light onto the imaging camera to form an image of the excitation focal spot, and the imaging camera converts the image of the excitation focal spot formed by the signal light into an electrical signal.

7. The plasma microscopy imaging system according to claim 6, characterized in that, The imaging camera includes a photodetector and a host computer. The photodetector is used to collect the converging signal light from the collecting lens and send the collected light signal to the host computer. The host computer is used to generate a microscopic image corresponding to the sample based on the light signal.

8. The plasma microscopy imaging system according to any one of claims 1 to 7, characterized in that, The metal film is made of a precious metal and is deposited on the substrate by means of a coating.

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