Lens unit and super-resolution microscopic imaging system

Abstract

The invention belongs to the technical field of optical imaging, and particularly discloses a lens unit and a super-resolution microscopic imaging system.The lens unit comprises a glass sleeve; the gradient refractive index lens is sleeved in the glass sleeve; the super-resolution lens is arranged at one end of the gradient refractive index lens; and the first single-mode optical fiber is connected to the other end of the gradient refractive index lens. The first single-mode optical fiber, the gradient refractive index lens and the super-resolution lens are utilized, the mode field area of output light beams of the single-mode optical fiber is enlarged, more wavefront control possibility is provided, more freedom degrees are conveniently provided for design of the super-resolution lens, and great convenience is provided for integration of the super-resolution lens into a microscopic imaging system due to the remarkable characteristics of miniaturization. Compared with the prior art, compactness and high efficiency of a microscopic system are promoted, the full width at half maximum of a single-mode Gaussian beam is increased, in addition, the formed super-resolution focus breaks through the traditional diffraction limit, and finer observation of sample characteristics can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of optical imaging and relates to a lens unit and a super-resolution microscopic imaging system. Background Art

[0002] A key parameter of an optical microscopy system is its spatial resolution, which is the ability to distinguish details of the imaged object. According to the Abbe-Rayleigh diffraction criterion, the traditional diffraction limit, i.e., the resolution, is limited to half the optical wavelength. This limitation makes it impossible for traditional optical microscopes to clearly observe microscopic structures smaller than the diffraction limit.

[0003] With the development of microscopic imaging technology, advanced imaging systems such as stimulated emission depletion microscopy and structured light illumination microscopy have been born. These microscopes can break through the traditional diffraction limit, that is, realize super-resolution microscopic imaging. However, in order to generate super-resolution light sources, the above-mentioned super-resolution microscopy systems are often highly complex, bulky, and cumbersome to operate.

[0004] With the introduction of the concept of fiber laboratory, the integration of metasurface and optical fiber (super fiber) has brought revolutionary changes to the field of optics and photonics. This provides the possibility of reducing the complexity and volume of the system while generating super-resolution light sources. However, since the mode field diameter of the output beam of a single-mode optical fiber is usually less than 10um, the degree of freedom of integrating a super-lens on the optical fiber output end face to control the amplitude and phase of the output beam is limited. The maximum numerical aperture (NA) of the optical fiber super-lens that can be achieved is 0.37. The necessary prerequisite for generating a super-resolution light source is sufficient freedom to control the output beam to achieve ultra-high NA focusing. Therefore, how to increase the mode field area of ​​the output beam of a single-mode optical fiber, so as to generate a super-resolution light source directly from the optical fiber end, remains a problem to be solved. Summary of the invention

[0005] The object of the present invention is to provide a lens unit and a super-resolution microscopic imaging system, which utilize single-mode optical fiber, a gradient refractive index lens and a super-resolution lens to expand the mode field area of ​​the single-mode optical fiber output light beam, provide more possibilities for wavefront manipulation, and provide more degrees of freedom for the design of the super-resolution lens to achieve a focused light spot beyond the diffraction limit for sample excitation.

[0006] To achieve the above purpose, the specific technical solutions provided by the present invention are as follows: A lens unit, comprising: Glass casing; A gradient refractive index lens, mounted on one end of the glass sleeve; A first single-mode optical fiber, sleeved and arranged at the other end of the glass sleeve; The super-resolution lens is located at an end of the gradient refractive index lens far away from the first single-mode optical fiber.

[0007] Furthermore, the super-resolution lens includes a chromium film and a gold film arranged in sequence, the chromium film is arranged close to the gradient refractive index lens, and the gold film includes a plurality of coaxially arranged annular areas, and the annular areas are used to divide the gold film into a plurality of shading areas and a plurality of light-transmitting areas.

[0008] Furthermore, the thickness of the chromium film is 3nm to 10nm.

[0009] Furthermore, the thickness of the gold film is 50nm to 150nm.

[0010] A transmission type super-resolution microscopic imaging system comprises the lens unit as described above, and further comprises: A first piezoelectric displacement platform, wherein the lens unit is located on one side of the first piezoelectric displacement platform; A first optical fiber polarization controller connected to the first single-mode optical fiber; A first laser is connected to the first optical fiber polarization controller through a second single-mode optical fiber, and the first laser is used to provide continuous laser; The objective lens, the beam splitter prism, the imaging tube lens, the field stop and the first detector are arranged in sequence, are located on the same optical path, and are located on the side of the first piezoelectric displacement platform away from the lens unit, and the objective lens is arranged close to the first piezoelectric displacement platform; The light source module is arranged on one side of the beam splitter prism and is used to illuminate the sample.

[0011] Furthermore, the light source module includes a first reflector, a second reflector and a first light source, and the light emitted by the first light source is reflected by the second reflector and the first reflector in sequence and then incident on the beam splitter prism.

[0012] A reflective super-resolution microscopic imaging system comprises the lens unit as described above, and further comprises: A second piezoelectric displacement platform, wherein the lens unit is located on one side of the second piezoelectric displacement platform; an optical fiber coupler connected to the first single-mode optical fiber; A second optical fiber polarization controller is connected to the optical fiber coupler via a fourth single-mode optical fiber; A second laser is connected to the second optical fiber polarization controller through a third single-mode optical fiber, and the second laser is used to provide continuous laser light; A second detector connected to the optical fiber coupler via a fifth single-mode optical fiber; A third reflector is arranged on the other side of the second piezoelectric displacement platform; The second light source is arranged on one side of the third reflector and is used to illuminate the sample. The light emitted by the second light source is reflected by the third reflector and then incident on the second piezoelectric displacement platform.

[0013] A nonlinear optical imaging super-resolution microscopic imaging system comprises the lens unit as described above, and further comprises: A second piezoelectric displacement platform, wherein the lens unit is located on one side of the second piezoelectric displacement platform; an optical fiber coupler connected to the first single-mode optical fiber; A second optical fiber polarization controller is connected to the optical fiber coupler via a fourth single-mode optical fiber; A third laser is connected to the second optical fiber polarization controller through a third single-mode optical fiber, and the third laser is used to provide femtosecond pulse laser with a near-infrared wavelength; A second detector connected to the optical fiber coupler via a fifth single-mode optical fiber; A filter is arranged between the second detector and the fifth single-mode optical fiber, and the filter is used to filter out the femtosecond excitation light; A third reflector is arranged on the other side of the second piezoelectric displacement platform; The second light source is arranged on one side of the third reflector and is used to illuminate the sample. The light emitted by the second light source is reflected by the third reflector and then incident on the second piezoelectric displacement platform.

[0014] Compared with the prior art, the lens unit and super-resolution microscopy imaging system of the present invention utilize a first single-mode optical fiber, a gradient refractive index lens and a super-resolution lens to integrate, thereby expanding the mode field area of ​​the single-mode optical fiber output light beam and providing more possibilities for wavefront manipulation, thereby providing more degrees of freedom for the design of the super-resolution lens to achieve a focused light spot beyond the diffraction limit for sample excitation, which is highly practical and worthy of promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic structural diagram of a lens unit provided by the present invention.

[0016] Figure 2 This is a schematic structural diagram of the transmission type super-resolution microscopic imaging system provided by the present invention.

[0017] Figure 3 This is a schematic structural diagram of the reflective super-resolution microscopic imaging system provided by the present invention.

[0018] Figure 4 This is a schematic structural diagram of the nonlinear optical imaging super-resolution microscopy system provided by the present invention.

[0019] Figure 5This is a scanning electron microscope photo of the super-resolution lens used in the embodiment of the present invention.

[0020] Figure 6 This is a scanning electron microscope image of the Siemens star-shaped resolution target provided by the present invention.

[0021] Figure 7 This is a super-resolution image taken using the microscope system of the present invention.

[0022] Reference numerals: 1. Lens unit, 101. First single-mode optical fiber, 102. Glass sleeve, 103. Gradient refractive index lens, 104. Super-resolution lens, 2. First laser, 3. Second single-mode optical fiber, 4. First optical fiber polarization controller, 5. First piezoelectric displacement platform, 6. Objective lens, 7. Beam splitter prism, 8. Imaging tube lens, 9. Field stop, 10. First detector, 11. First reflector, 12. Second reflector, 13. First light source, 14. Second laser, 15. Third single-mode optical fiber, 16. Second optical fiber polarization controller, 17. Fourth single-mode optical fiber, 18. Optical fiber coupler, 19. Second piezoelectric displacement platform, 20. Third reflector, 21. Second light source, 22. Fifth single-mode optical fiber, 23. Second detector, 24. Filter, 25. Third laser. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solution of the present invention and to implement it, Figures 1 to 7 , clearly and comprehensively describe the technical solution in the present invention.

[0024] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0025] In addition, it should be further explained that, in the description of the embodiments of the present invention, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B: “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present invention, “multiple” refers to two or more than two.

[0026] The following terms "first", "second", "third" and "fourth" are used for descriptive purposes only and should not be understood as suggesting or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", "third" and "fourth" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0027] like Figure 1 As shown, the lens unit 1 is integrated by a first single-mode optical fiber 101, a glass sleeve 102, a gradient refractive index lens 103 and a super-resolution lens 104. The gradient refractive index lens 103 is mounted on one end of the glass sleeve 102, and the first single-mode optical fiber 101 is mounted on the other end. The super-resolution lens 104 is arranged at the end of the gradient refractive index lens 103 away from the first single-mode optical fiber 101. The super-resolution lens 104 includes a chromium film and a gold film arranged in sequence, and the gold film includes a plurality of coaxially arranged annular regions, and the annular regions are used to divide the gold film into a plurality of light-shielding regions and a plurality of light-transmitting regions. The chromium film is arranged close to the gradient refractive index lens 103.

[0028] In the specific manufacturing process of the lens unit 1, it is necessary to pre-install and fix a pigtail ferrule on one end of the first single-mode optical fiber 101. The outer diameter of the pigtail ferrule matches the inner diameter of the glass sleeve 102. Alternatively, a single-mode optical fiber with a pigtail ferrule can be directly purchased on the market and used as the first single-mode optical fiber 101.

[0029] In addition, the super-resolution lens 104 is formed by depositing a 3nm to 10nm thick chromium film as a substrate on the gradient refractive index lens 103, and then depositing a 50nm to 150nm thick gold film, and then using a focused ion beam to etch preset concentric rings on the gold film. After completion, the gold film includes a plurality of coaxially arranged ring areas, the ring area of ​​the gold film forms a light-shielding area that light cannot penetrate, and the ring part of the un-gold-plated film forms a light-transmitting area, such as Figure 5 An electron microscope image of the super-resolution lens 104 integrated on the gradient refractive index lens 103 is shown.

[0030] Preferably, the thickness of the chromium film can be determined empirically and is in the range of 3 nm to 10 nm.

[0031] Preferably, the thickness of the gold film is 50 nm to 150 nm.

[0032] Specifically, in the present invention, the thickness of the chromium film is 5 nm, and the thickness of the gold film is 100 nm.

[0033] When assembling lens unit 1: First, the gradient refractive index lens 103 is installed in the glass sleeve 102, UV glue is applied to the contact surface between the gradient refractive index lens 103 and the glass sleeve 102, and then cured using an ultraviolet lamp.

[0034] If high connection reliability is required, 353ND glue can be applied at the waist seam so that the 353ND glue flows all over the contact position between the outer wall of the gradient refractive index lens 103 and the inner wall of the glass sleeve 102, but the 353ND glue cannot flow to the end face of the gradient refractive index lens 103, and then the 353ND glue is cured by high-temperature baking.

[0035] Place the pigtail ferrule into the glass sleeve 102 equipped with the gradient refractive index lens 103, connect the other end of the first single-mode optical fiber 101 to the light source, adjust the distance between the gradient refractive index lens 103 and the pigtail ferrule until the output light spot meets the requirements, use UV glue to fix the pigtail ferrule to the glass sleeve 102, and if high connection reliability is required, use 353ND glue to further achieve bonding and fixation.

[0036] Compared with the prior art, the lens unit 1 provided by the present invention breaks through the diffraction limit of traditional optics, realizes super-resolution imaging, and has a highly integrated structure. It only uses the first single-mode optical fiber 101, the gradient refractive index lens 103 and the super-resolution lens 104 to directly generate a super-resolution light source at the output end. The super-resolution light source can be generated by the fundamental mode Gaussian light of the lens unit 1.

[0037] The present invention utilizes the main body of the integrated lens unit 1 of the first single-mode optical fiber 101, the gradient refractive index lens 103 and the super-resolution lens 104, thereby expanding the mode field area of ​​the single-mode optical fiber and providing more wavefront control possibilities, so as to provide more degrees of freedom for the design of the lens, so as to achieve a focused light spot beyond the diffraction limit for sample excitation, and in combination with imaging equipment such as an objective lens, an imaging tube lens, an optical fiber coupler, and a detector, multiple sets of super-resolution imaging systems can be constructed, which will be further described below based on three embodiments and drawings.

[0038] Example 1 Transmission super-resolution microscopy system like Figure 1 and Figure 2 As shown, the transmission super-resolution microscopy system includes a lens unit 1, a first laser 2, a second single-mode optical fiber 3, a first optical fiber polarization controller 4, a first piezoelectric displacement platform 5, an objective lens 6, a beam splitter prism 7, an imaging tube lens 8, a field aperture 9, a first detector 10 and a light source module, wherein the light source module includes a first reflector 11, a second reflector 12 and a first light source 13, the first laser 2 is used to provide continuous laser, and the first light source 13 is preferably an LED light source.

[0039] Specifically, the lens unit 1 is located on one side of the first piezoelectric displacement platform 5, the first optical fiber polarization controller 4 is connected to the first single-mode optical fiber 101, the first laser 2 is connected to the first optical fiber polarization controller 4 through the second single-mode optical fiber 3, the objective lens 6, the beam splitter prism 7, the imaging tube lens 8, the field stop 9 and the first detector 10 are arranged in sequence and located on the same optical path, the objective lens 6 is arranged close to the first piezoelectric displacement platform 5, and the light source module is arranged on one side of the beam splitter prism 7 for illuminating the sample.

[0040] like Figure 1 and Figure 2 As shown, firstly, the first light source 13 is used to emit white light, and the light beam is reflected by the second reflector 12 and the first reflector 11 to the beam splitter prism 7 and collected by the objective lens 6. The sample is a Siemens star-shaped resolution target, which is in the shape of a 36-sector Siemens star and is the recommended sample for the resolution test of the current microscopic imaging system. Figure 6 As shown in the electron microscope image, the objective lens 6 in the imaging module is used to illuminate the sample, and the light reflected by the sample is received, and then passes through the beam splitter prism 7 and the imaging tube lens 8 in sequence, and is collected by the first detector 10. The sample position is determined by observing the image on the first detector 10, and the first light source 13 is turned off. Subsequently, the first laser 2 emits a laser with a wavelength of 633nm and a half-width of 8.2um, which is transmitted to the second single-mode optical fiber 3, the first optical fiber polarization controller 4, and the lens unit 1 in sequence. The lens unit 1 generates a super-resolution focus, and the first optical fiber polarization controller 4 is rotated and the polarization state of the light beam is modulated by the first optical fiber polarization controller 4, so that the light beam emitted from the lens unit 1 is a stable circularly polarized light. The main purpose of this design is to make the super-resolution focus generated by the lens unit 1 have circular symmetry.

[0041] Specifically, the focal length of the imaging tube lens 8 is f=200 mm.

[0042] Specifically, the numerical aperture NA of the objective lens 6 is 0.90, and the magnification M is 100X.

[0043] Specifically, the first light source 13 is preferably an LED light source.

[0044] The fundamental mode Gaussian beam with a wavelength of 633nm transmitted to the lens unit 1 is transmitted on the gradient refractive index lens 103 in the lens unit 1, and the half-maximum full width of the fundamental mode Gaussian beam is magnified from 8.2um to 160um, and then passes through the super-resolution lens 104 in the lens unit 1 to form a super-resolution focus with a focal length of 30um and a half-maximum full width of 0.4 times the wavelength, i.e. 253.2nm.

[0045] The sample is illuminated by the super-resolution focus generated by the lens unit 1, and then the transmitted light after irradiating the sample is collected by the objective lens 6. After passing through the beam splitter prism 7 and the imaging tube lens 8, the stray light around the focus is filtered out by the field diaphragm 9 and collected by the first detector 10.

[0046] The first piezoelectric displacement platform 5 controls the sample to move at equal intervals in micrometer or nanometer levels to achieve the function of point-by-point scanning of the sample. Each equal interval movement will send a signal to the first detector 10, and the first detector 10 will receive the signal to collect the focus signal after the field of view diaphragm 9 filters out stray light. Through the above point-by-point scanning and data processing of the focus signal collected by the first detector 10, a super-resolution microscopic image of the sample Siemens star-shaped resolution target can be obtained, as shown in FIG. Figure 7 As shown, the achieved resolution is as high as 253.2nm, and the effective numerical aperture NA=1.25.

[0047] The parameters of the above-mentioned transmission super-resolution microscopy system are: 1. Objective lens: NA=0.9, magnification 100X; 2. Imaging tube lens f=200mm; 3. Resolution 253.2nm, effective numerical aperture NA=1.25.

[0048] Example 2 Reflective super-resolution microscopy system like Figure 1 and Figure 3 As shown, the reflective super-resolution microscopy system includes a second laser 14, a third single-mode optical fiber 15, a second optical fiber polarization controller 16, a fourth single-mode optical fiber 17, an optical fiber coupler 18, a lens unit 1, a second piezoelectric displacement platform 19, a third reflector 20, a second light source 21, a fifth single-mode optical fiber 22 and a second detector 23.

[0049] Specifically, the second laser 14 is used to provide continuous laser light, and the second light source 21 is preferably an LED light source.

[0050] The lens unit 1 is located on one side of the second piezoelectric displacement platform 19, the fiber coupler 18 is connected to the first single-mode optical fiber 101, the second fiber polarization controller 16 is connected to the fiber coupler 18 through the fourth single-mode optical fiber 17, the second laser 14 is connected to the second fiber polarization controller 16 through the third single-mode optical fiber 15, the second detector 23 is connected to the fiber coupler 18 through the fifth single-mode optical fiber 22, the third reflector 20 is arranged on the other side of the second piezoelectric displacement platform 19, the second light source 21 is arranged on one side of the third reflector 20, and is used to illuminate the sample, and the light emitted by the second light source 21 is reflected by the third reflector 20 and then incident on the sample on the second piezoelectric displacement platform 19.

[0051] like Figure 1 and Figure 3 As shown, firstly, the second light source 21 is used to emit white light, and the sample located on the second piezoelectric displacement platform 19 is illuminated through the third reflector 20, wherein the sample is a Siemens star-shaped resolution target, which has a shape of a Siemens star with 36 sectors and is a recommended sample for resolution testing of a current microscopic imaging system, such as Figure 6 As shown in the electron microscope image, the transmitted light irradiating the sample is collected by the lens unit 1. It is collected by the second detector 23 through the fiber coupler 18 and the fifth single-mode optical fiber 22. Through the above operation, the sample position is determined, and the second light source 21 is turned off. Then, the second laser 14 emits a laser with a wavelength of 633nm and a half-width of 8.2um, which passes through the third single-mode optical fiber 15, the second optical fiber polarization controller 16, and the lens unit 1 in sequence. The lens unit 1 generates a super-resolution focus. By rotating the second optical fiber polarization controller 16, the light beam emitted by the lens unit 1 is a stable circularly polarized light. The main purpose of this design is to make the super-resolution focus generated by the lens unit 1 have circular symmetry.

[0052] The fundamental mode Gaussian beam with a wavelength of 633 nm transmitted to the lens unit 1 is magnified from 8.2 um to 160 um at half maximum by the transmission of the gradient refractive index lens 103 in the lens unit 1, and then forms a super-resolution focus with a focal length of 30 um and a half maximum full width of 0.4 times the wavelength of 253.2 nm by the super-resolution lens 104 in the lens unit 1.

[0053] The sample is irradiated with the super-resolution focus generated by the lens unit 1, and then the reflected light after irradiating the sample is collected by the lens unit 1, and then coupled to the fifth single-mode optical fiber 22 through the optical fiber coupler 18, and the reflected light signal is collected by the second detector 23.

[0054] The second piezoelectric displacement platform 19 controls the sample to move at equal intervals in the micrometer or nanometer level to achieve the function of point-by-point scanning of the sample. The second piezoelectric displacement platform 19 sends a signal to the second detector 23 every time it moves at equal intervals. The second detector 23 receives the signal to collect the intensity signal of the fifth single-mode optical fiber 22. Through the above-mentioned point-by-point scanning and data processing of the intensity signal collected by the second detector 23, a super-resolution microscopic image of the sample Siemens star-shaped resolution target can be obtained, as shown in FIG. Figure 7 shown.

[0055] Example 3 Nonlinear optical imaging super-resolution microscopy system like Figure 1 and Figure 4As shown, the nonlinear optical imaging super-resolution microscopy system includes a third laser 25, a third single-mode optical fiber 15, a second optical fiber polarization controller 16, a fourth single-mode optical fiber 17, an optical fiber coupler 18, a lens unit 1, a second piezoelectric displacement platform 19, a third reflector 20, a second light source 21, a fifth single-mode optical fiber 22, a filter 24 and a second detector 23.

[0056] Specifically, the lens unit 1 is located on one side of the second piezoelectric displacement platform 19, the fiber coupler 18 is connected to the first single-mode optical fiber 101, the second fiber polarization controller 16 is connected to the fiber coupler 18 through the fourth single-mode optical fiber 17, and the third laser 25 is connected to the second fiber polarization controller 16 through the third single-mode optical fiber 15, and the third laser 25 is used to provide a femtosecond pulse laser with a near-infrared wavelength. The second detector 23 is connected to the fiber coupler 18 through the fifth single-mode optical fiber 22, and the filter 24 is arranged between the second detector 23 and the fifth single-mode optical fiber 22 to filter out the femtosecond excitation light. The third reflector 20 is arranged on the other side of the second piezoelectric displacement platform 19, and the second light source 21 is arranged on one side of the third reflector 20 to illuminate the sample. The light emitted by the second light source 21 is incident on the second piezoelectric displacement platform 19 after being reflected by the third reflector 20.

[0057] like Figure 1 and Figure 4As shown, first, the second light source 21 is used to emit white light, and the sample located on the second piezoelectric displacement platform 19 is illuminated through the third reflector 20. Here, the sample has a fluorescent label or has a nonlinear optical effect itself, so as to be applied to different nonlinear optical imaging. Here, a fluorescent label sample is taken as an example. Then, the lens unit 1 collects the transmitted light of the illuminated sample, and the light is collected by the second detector 23 through the fiber coupler 18 and the fifth single-mode fiber 22. Through the above operation, the sample position is determined, and the second light source 21 is turned off. Then, the third laser 25 emits a near-infrared wavelength femtosecond pulse laser, which passes through the third single-mode fiber 15, the second fiber polarization controller 16, the fourth single-mode fiber 17, the fiber coupler 18, and the lens unit 1 in sequence. The lens unit 1 generates a super-resolution focus. By rotating the second fiber polarization controller 16, the light beam emitted from the lens unit 1 is a stable circularly polarized light. The main purpose of this design is to make the super-resolution focus generated by the lens unit 1 have circular symmetry. The super-resolution focus generated by the lens unit 1 irradiates the fluorescent sample, and excites the sample to produce nonlinear optical effects, such as two-photon absorption, Raman scattering, and anti-Stokes Raman scattering, which serves as signal light. The super-resolution lens 104 takes into account the nonlinear optical effect. As required, the super-resolution lens 104 is achromatically designed to collect fluorescence signals in a band smaller than the wavelength of the excitation light. The achromatically designed structure is the same as the super-lens designed by us, and the concentric rings are still etched on the gold film by focused ion beam etching, but the distribution of the concentric rings is different. The lens unit 1 is used to collect the fluorescence signal and the excitation light, and is coupled to the fifth single-mode optical fiber 22 through the optical fiber coupler 18. The excitation light is filtered out by the filter 24, and the fluorescence signal is collected by the second detector 23.

[0058] The sample is controlled to move at equal intervals in nanometers by the second piezoelectric displacement platform 19. Each equal interval movement sends a signal to the second detector 23, and the second detector 23 receives the signal to collect the intensity signal of the fifth single-mode optical fiber 22. Through the above-mentioned point-by-point scanning and data processing of the intensity signal collected by the second detector 23, a fluorescence super-resolution microscopic image of the sample can be obtained.

[0059] The lens unit and super-resolution microscopic imaging system of the present invention are based on the integration of optical fiber, gradient refractive index lens and super-resolution lens, and with the remarkable feature of miniaturization, provide great convenience for integration into the microscopic imaging system, and promote the compactness and efficiency of the microscopic system. At the same time, the integration of single-mode optical fiber and gradient refractive index lens also increases the half-height full width of the single-mode Gaussian beam, and increases the integration area of ​​the super-resolution lens to achieve more wavefront manipulation. In addition, the super-resolution focus formed breaks through the traditional diffraction limit and can achieve more detailed observation of sample features.

[0060] Compared with the prior art, the present invention has the following advantages: 1. The single-mode optical fiber, gradient refractive index lens and super-resolution lens are used to expand the mode field radius of the fundamental mode Gaussian beam from several microns to tens to hundreds of microns, which can increase the integration area of ​​the super-resolution lens and provide favorable conditions for realizing more diverse wavefront manipulation.

[0061] 2. The output beam of the system is a single-mode beam with a very stable wavefront, which is convenient for designing a matching planar super-resolution lens. Its polarization state can be controlled online in real time using a fiber polarization controller, which facilitates precise control.

[0062] 3. The lens unit has the remarkable feature of miniaturization, which provides great convenience for integration into the microscopic imaging system and promotes the compactness and efficiency of the system.

[0063] 4. The super-resolution imaging system is centered on super-resolution capability, which can break through the constraints of traditional diffraction limits and achieve more detailed observation and exploration of sample characteristics.

[0064] 5. Transmission super-resolution microscopy imaging system and reflection super-resolution microscopy imaging system have wider imaging application fields and potential due to their label-free imaging characteristics.

[0065] It will be understood that the present invention is described through some embodiments, and those skilled in the art will appreciate that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention.

[0066] In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present invention are within the scope of protection of the present invention.

Claims

1. A lens unit, characterized in that: include: Glass sleeve (102); A gradient refractive index lens (103), which is mounted on one end of the glass sleeve (102); A first single-mode optical fiber (101), which is sleeved and arranged at the other end of the glass sleeve (102); The super-resolution lens (104) is located at an end of the gradient refractive index lens (103) far away from the first single-mode optical fiber (101).

2. The lens unit according to claim 1, characterized in that: The super-resolution lens (104) comprises a chromium film and a gold film which are arranged in sequence, the chromium film being arranged close to the gradient refractive index lens (103), the gold film comprising a plurality of coaxially arranged annular regions, the annular regions being used to divide the gold film into a plurality of light-shielding regions and a plurality of light-transmitting regions.

3. The lens unit according to claim 2, characterized in that: The thickness of the chromium film is 3 nm to 10 nm.

4. The lens unit according to claim 2, characterized in that: The thickness of the gold film is 50 nm to 150 nm.

5. A transmission super-resolution microscopic imaging system, characterized in that: The lens unit comprises any one of claims 1 to 4, further comprising: A first piezoelectric displacement platform (5), wherein the lens unit is located on one side of the first piezoelectric displacement platform (5); A first optical fiber polarization controller (4) connected to the first single-mode optical fiber (101); A first laser (2) is connected to the first optical fiber polarization controller (4) via a second single-mode optical fiber (3), and the first laser (2) is used to provide continuous laser light; An objective lens (6), a beam splitter prism (7), an imaging tube lens (8), a field stop (9), and a first detector (10) are arranged in sequence and are located on the same optical path and on a side of the first piezoelectric displacement platform (5) away from the lens unit, with the objective lens (6) being arranged close to the first piezoelectric displacement platform (5); A light source module is arranged on one side of the beam splitter prism (7) and is used to illuminate the sample.

6. The transmission super-resolution microscopic imaging system according to claim 5, characterized in that: The light source module comprises a first reflector (11), a second reflector (12) and a first light source (13); light emitted by the first light source (13) is reflected by the second reflector (12) and the first reflector (11) in sequence and then incident on the beam splitting prism (7).

7. A reflective super-resolution microscopic imaging system, characterized in that: The lens unit comprises any one of claims 1 to 4, further comprising: A second piezoelectric displacement platform (19), wherein the lens unit is located on one side of the second piezoelectric displacement platform (19); An optical fiber coupler (18) connected to the first single-mode optical fiber (101); A second optical fiber polarization controller (16) connected to the optical fiber coupler (18) via a fourth single-mode optical fiber (17); A second laser (14) connected to the second optical fiber polarization controller (16) via a third single-mode optical fiber (15), the second laser (14) being used to provide continuous laser light; A second detector (23) connected to the optical fiber coupler (18) via a fifth single-mode optical fiber (22); A third reflecting mirror (20) is arranged on the other side of the second piezoelectric displacement platform (19); The second light source (21) is arranged on one side of the third reflector (20) and is used to illuminate the sample; the light emitted by the second light source (21) is reflected by the third reflector (20) and then incident on the second piezoelectric displacement platform (19).

8. A nonlinear optical imaging super-resolution microscopy system, characterized in that: The lens unit comprises any one of claims 1 to 4, further comprising: A second piezoelectric displacement platform (19), wherein the lens unit is located on one side of the second piezoelectric displacement platform (19); An optical fiber coupler (18) connected to the first single-mode optical fiber (101); A second optical fiber polarization controller (16) connected to the optical fiber coupler (18) via a fourth single-mode optical fiber (17); A third laser (25) is connected to the second optical fiber polarization controller (16) via a third single-mode optical fiber (15), wherein the third laser (25) is used to provide femtosecond pulse laser light with a near-infrared wavelength; A second detector (23) connected to the optical fiber coupler (18) via a fifth single-mode optical fiber (22); An optical filter (24) is arranged between the second detector (23) and the fifth single-mode optical fiber (22), and the optical filter (24) is used to filter out femtosecond excitation light; A third reflecting mirror (20) is arranged on the other side of the second piezoelectric displacement platform (19); The second light source (21) is arranged on one side of the third reflector (20) and is used to illuminate the sample; the light emitted by the second light source (21) is reflected by the third reflector (20) and then incident on the second piezoelectric displacement platform (19).

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