A microsphere lens set and a full microsphere optical nanoscope

Abstract

The present invention relates to the field of optical imaging, and in particular to a microsphere lens group and a full-microsphere optical nanoscope. The invention provides a microsphere lens group, comprising: a plurality of microsphere lenses, wherein the plurality of microsphere lenses are vertically stacked in a coaxial manner. The present invention achieves a magnification and a real image imaging mode that exceed those of a single optical microsphere by designing a lens group composed of a plurality of microsphere lenses, so that the image of the nanostructure projected onto the optical camera can be directly distinguished, thereby realizing optical nanomicroscopic imaging of the full microsphere. The present invention provides a full-microsphere optical nanoscope, comprising: a light source device; a microsphere lens group; a lens group bracket; and a photoelectric conversion device. The full-microsphere optical nanoscope provided by the present invention has the ability to magnify the real image of a nanostructured sample, so that it is within the scale range that the photoelectric conversion device can distinguish, and has the advantages of simple preparation process, low price, high resolution, compact and portable structure, etc.

Description

Technical Field

[0001] The invention relates to the field of optical imaging, and in particular to a microsphere lens group and a full microsphere optical nanoscope. Background Art

[0002] Optical microscopy is an important technical means to characterize micro- and nano-scale objects. It is widely used in industrial production, scientific research, and teaching. Resolution is an important evaluation index of optical microscopy technology. Limited by the diffraction effect of light waves, it can only reach about half of the wavelength of light in ordinary optical microscopes. In recent years, many super-resolution imaging technologies have been developed to break through the optical diffraction limit and thus improve the resolution of optical microscopy. Among them, optical microsphere nanomicroscopy has received widespread attention from scientific research and industry. This is mainly because compared with other super-resolution imaging technologies, optical microsphere nanomicroscopy has the advantages of high resolution, no need for fluorescent labeling, low cost, and compatibility with traditional optical microscopes. However, since the magnification of a single microsphere is generally less than about 5 times, the microsphere still needs to be used in conjunction with a traditional optical microscope objective to achieve nano imaging. This results in a large volume of the entire imaging device and difficulty in reducing production costs.

[0003] In recent years, a lens group consisting of two microspheres has been used to increase the magnification and has achieved good results. With the help of a microsphere lens group consisting of two microspheres, a traditional optical microscope only needs to be equipped with a 10× objective lens to achieve optical nano imaging. Since a high-magnification objective lens is not required, the manufacturing cost of the device is reduced to a certain extent. However, the microsphere lens groups currently realized are all in a non-fixed state, and the two microspheres that constitute the lens group are easily misaligned and cannot be used as a stable whole. In addition, the objective lens is still indispensable in microsphere nano imaging, which makes the cost still high and the device is large. At present, there is no miniaturized, portable optical microsphere nano imaging device. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art and to provide a microsphere lens group and a full microsphere optical nanoscope that does not require an objective lens, which has the advantages of simple device, low price, high imaging resolution and wide applicability.

[0005] In order to solve the above technical problems, the present invention provides a microsphere lens assembly, comprising:

[0006] A plurality of micro-ball lenses, wherein the plurality of micro-ball lenses are stacked vertically in a coaxial manner;

[0007] The microsphere lenses are defined as the first microsphere lens, the second microsphere lens, and the i-th microsphere lens from near to far according to the distance from the sample;

[0008] The distance between the imaging surface position of the microball lens group composed of k microball lenses and the vertex of the microball lens satisfies the following formula:

[0009]

[0010] n0 refers to the refractive index of the environment, n1 refers to the refractive index of the first microsphere lens, and n i refers to the refractive index of the i-th microsphere lens; r1 refers to the radius of the first microsphere lens, r i refers to the radius of the i-th microsphere lens; l0 refers to the distance between the sample and the lower vertex of the first microsphere lens, which takes a negative value in the calculation; l′1 refers to the distance between the imaging surface position of the first microsphere lens and the upper vertex of the first microsphere lens; l′ i It refers to the distance between the imaging surface position of the i-th microsphere lens and the vertex on the corresponding microsphere lens;

[0011] The distance l′ between the imaging surface position of the kth microsphere lens and the vertex of the corresponding microsphere lens k is greater than 0, so that the imaging plane is located on the side of the kth microsphere lens away from the sample. In a more preferred embodiment, the magnification β of the microsphere lens group composed of k microsphere lenses satisfies the following formula:

[0012]

[0013] Where β1 refers to the magnification of the first microsphere lens, β i refers to the magnification of the i-th microsphere lens, β refers to the total magnification of the entire microsphere lens group; g i It refers to the distance between the i-th microsphere lens and the i-1-th microsphere lens, which takes a negative value in the calculation.

[0014] In a more preferred embodiment, the magnification of the microsphere lens group is greater than 8 times.

[0015] In a more preferred embodiment, the distance between any two adjacent micro-ball lenses is the same or different, and the distance between any two adjacent micro-ball lenses is greater than or equal to 0.

[0016] In a more preferred embodiment, the diameter of the microsphere lens is greater than 1 μm and less than 3 mm.

[0017] In a more preferred embodiment, the diameter of the first microsphere lens is greater than 20 μm and less than 50 μm.

[0018] The present invention provides a full microsphere optical nanoscope, comprising:

[0019] A light source device, which is used to optically illuminate the sample to be observed;

[0020] A microball lens assembly, wherein the microball lens assembly is a microball lens assembly as claimed in any one of claims 1 to 5, and is used to collect and amplify reflected or transmitted light carrying information of a sample to be observed;

[0021] A lens group bracket, which is used to define the position of each microball lens in the microball lens group;

[0022] A photoelectric conversion device is used to collect and resolve the image formed by the microsphere lens group.

[0023] In a more preferred embodiment, the roughness of the upper and lower surfaces of the lens assembly bracket is less than 1 μm.

[0024] In a more preferred embodiment, the lower vertex of the first microsphere lens exceeds the lower surface of the lens group support or is flush with the lower surface of the lens group support.

[0025] In a more preferred embodiment, the total magnification of the microsphere lens group satisfies the following conditions:

[0026] β ≥ 2x / d;

[0027] d refers to the size of the smallest feature to be observed on the sample to be observed, and x refers to the pixel width of the photoelectric conversion device.

[0028] The full microsphere optical nanoscope provided by the present invention can be applied in the fields of semiconductor chip detection, biological imaging, and chemistry.

[0029] In summary, the present application includes at least one of the following beneficial technical effects:

[0030] (1) Using optical microspheres as the core of optical elements for imaging can achieve a resolution beyond the diffraction limit;

[0031] (2) It does not require macroscopic optical elements such as objective lenses, and is simple in design and very low in cost;

[0032] (3) The entire microscope has a compact structure and is extremely small, making it easy to carry;

[0033] (4) It has the potential to further develop the on-chip experimental platform.

[0034] Other features and beneficial effects of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other beneficial effects of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. The positional relationships described in the drawings in the following description are based on the directions in which the components are drawn in the diagrams, unless otherwise specified.

[0036] Figure 1 A schematic structural diagram of a full microsphere optical nanoscope provided by one embodiment of the present invention;

[0037] Figure 2 Used to demonstrate the manufacturing process of fixing the microsphere lens group inside PDMS;

[0038] Figure 3 A schematic diagram of the alignment process of each layer of microspheres in a microsphere lens assembly provided in an embodiment of the present invention and a top-view microscope photograph of the microsphere lens assembly in Example 1;

[0039] Figure 4 This is a diagram showing the imaging result of a sample by a micro-ball lens group composed of double-layer ball lenses in Example 1 of the present invention;

[0040] Figure 5 1 is a diagram showing the calculation results of the magnification and projection distance of a micro-ball lens group composed of three layers of ball lenses in Example 2 of the present invention;

[0041] Figure 6 This is a diagram showing the imaging result of a sample by a micro-ball lens group consisting of three layers of ball lenses in Example 2 of the present invention. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; the technical features designed in different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0043] In the description of the present invention, it should be noted that all terms used in the present invention (including technical terms and scientific terms) have the same meanings as those generally understood by ordinary technicians in the field to which the present invention belongs, and cannot be understood as limiting the present invention; it should be further understood that the terms used in the present invention should be understood to have the same meanings as these terms in the context of this specification and in the relevant fields, and should not be understood in an idealized or overly formal sense, unless explicitly defined in the present invention.

[0044] Although the numerical ranges and parameters listed for the broad scope of the present invention are approximate, the numerical values ​​listed in the specific examples are recorded as accurately as possible. However, any numerical value inherently has a certain error. The error is the inevitable result of the standard deviation obtained in its corresponding measurement method.

[0045] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] Please refer to Figure 1 According to one embodiment of the present invention, a full microsphere optical nanoscope is provided, comprising:

[0047] A light source device is used to optically illuminate the sample to be observed; the light source device in this embodiment can be any light source that can meet the lighting requirements of microscopic imaging, such as sunlight or a traditional lighting source; in addition, the light source device can adopt any lighting method, including reflective lighting and transmissive lighting, etc., with the sample surface as the boundary. If the light source device is arranged on the same side as the microsphere lens group and the photoelectric conversion device, it is necessary to adjust the lighting angle of its light source to reduce the influence of stray light on the imaging effect.

[0048] Microsphere lens set, which is used to collect and amplify the reflected or transmitted light carrying the information of the sample to be observed; please continue to refer to Figure 1 In this embodiment, the microball lens group includes a plurality of microball lenses, and the plurality of microball lenses are vertically stacked in a coaxial manner;

[0049] The ball lenses are defined as the first micro-ball lens, the second micro-ball lens, and the i-th micro-ball lens in order from near to far according to the distance from the sample;

[0050] Specifically, the microsphere lens group is the core element of the full microsphere optical nano microscope provided by the present invention. The microsphere lens group is composed of a number of (≥2) micrometer to millimeter scale ball lenses, which are vertically stacked and assembled in a coaxial manner, and the material used to make these balls is transparent within the spectral range of the illumination light source used. Preferably, the diameter of these ball lenses is above 1μm and below 3mm. The spacing between any two adjacent ball lenses is the same or different, and the spacing between any two adjacent ball lenses is greater than or equal to 0, that is, these ball lenses can be completely close together or maintain a certain distance. Since the image of the sample to be observed magnified by the microsphere lens group needs to be directly detected by the photoelectric conversion device, the ball lens closest to the photoelectric conversion device in the microsphere lens group must work in the real image imaging mode and be able to project the real image far enough to leave enough space for placing and adjusting the position of the photoelectric conversion device.

[0051] The imaging process of a microsphere lens group consisting of k (k>2) microsphere lenses can be understood as follows: First, the first microsphere lens images the object. The image it produces is used as the imaging object of the second microsphere lens and is imaged by the second microsphere lens, and so on, until the kth microsphere lens uses the image generated by the k-1th microsphere lens as the object to image, and the final imaging result of the entire microsphere lens group can be obtained. The serial number of the microspheres in the microsphere lens group increases from near to far according to the distance of the microspheres from the sample. The first microsphere lens and the kth microsphere lens are the microspheres closest to and farthest from the sample in the lens group, respectively.

[0052] Therefore, the distance between the imaging surface position of the micro-ball lens group composed of k micro-ball lenses and the top vertex of the ball lens satisfies the following formula (1):

[0053]

[0054] n0 refers to the refractive index of the environment, n1 refers to the refractive index of the first microsphere lens, and n i refers to the refractive index of the i-th microsphere lens; r1 refers to the radius of the first microsphere lens, r i refers to the radius of the i-th microsphere lens; l0 refers to the distance between the sample and the lower vertex of the first microsphere lens, which takes a negative value in the calculation; l′1 refers to the distance between the imaging surface position of the first microsphere lens and the upper vertex of the first microsphere lens; l′ i It refers to the distance between the imaging surface position of the i-th micro-ball lens and the vertex on the corresponding ball lens;

[0055] When the value calculated by formula (1) is positive, the imaging plane is located above the upper vertex of the first microsphere lens or the i-th microsphere lens, respectively, and if it is negative, it is located below the upper vertex of the first microsphere lens or the i-th microsphere lens. In the present invention, the k-th microsphere lens in the microsphere lens group composed of k microsphere lenses must work in the real image imaging mode, and therefore, it must meet the following conditions: l′ k Should be greater than 0, that is, the distance l′ between the imaging surface position of the kth microsphere lens and the vertex of the corresponding microsphere lens k Should be greater than 0.

[0056] In addition, the magnification of the microsphere lens group needs to be designed to be as large as possible to ensure imaging contrast, aberration and other factors, so that smaller objects can be resolved by the entire device, so as to better observe the sample. Preferably, the magnification of the microsphere lens group is greater than 8 times. In the present invention, the magnification β of the microsphere lens group composed of k microsphere lenses satisfies the following formula (2):

[0057]

[0058] Where β1 refers to the magnification of the first microsphere lens, β i refers to the magnification of the i-th microsphere lens, β refers to the total magnification of the entire microsphere lens group; g i It refers to the distance between the i-th microsphere lens and the i-1-th microsphere lens, which takes a negative value in the calculation.

[0059] When the pixel width of the photoelectric conversion device is x, the total magnification of the microsphere lens group satisfies the following conditions:

[0060] β ≥ 2x / d;

[0061] d refers to the size of the smallest feature to be observed on the sample to be observed.

[0062] According to the above formulas (1) and (2), the imaging mode (real image or virtual image), imaging surface position, and magnification of the entire lens can be achieved by selecting microsphere lenses with different refractive indices, changing the size of each microsphere lens, and the gap between the microsphere lenses. In addition, under the condition of satisfying the real image imaging mode and a sufficiently large magnification, the first microsphere lens located at the bottom close to the sample in the microsphere lens group needs to have a size as small as possible and a high refractive index to maintain a high resolution. However, if the microsphere lens is too small, its imaging field of view will be very small, which is not conducive to the actual use of the microscope. Therefore, when selecting the size of the first microsphere lens, it is necessary to balance the resolution and imaging field of view of the microsphere lens. Generally, it is preferred to use a microsphere lens with a diameter of more than 20 μm and less than 50 μm;

[0063] It should be noted that (1) when the lens group to be constructed is required to have a resolution beyond the optical diffraction limit (<λ / 2, λ is the wavelength of the illumination light), the diameter of the first microsphere lens is preferably greater than 20 μm and less than 50 μm. If the size of the microsphere lens is too small, its imaging field of view will be too small and difficult to control; if the size of the microsphere lens is too large, the resolution of the microsphere lens will decrease;

[0064] (2) When the constructed lens group is not required to have a resolution beyond the optical diffraction limit, the distance l0 between the first microsphere lens and the sample and the size d of the resolved sample preferably satisfy the following conditions:

[0065]

[0066] Among them, λ refers to the wavelength of the illumination light, D1 refers to the diameter of the first microsphere lens, and n0 refers to the refractive index of the environment in which the microsphere lens is located.

[0067] The microsphere lens at the top of the lens group close to the photoelectric conversion device needs to be as large as possible so that the generated image can be projected to a sufficiently far position to facilitate the installation of the photoelectric conversion device. Specifically, in the present invention, from the perspective of actual manufacturing, the reason why the diameter of the k-th microsphere lens needs to be selected to be larger is that the larger the ball lens, the farther the real image is projected from the lens group, which can leave more operating space for the placement of the photoelectric conversion device; if it is only from the perspective of optical imaging principles, the diameter of the k-th microsphere lens only needs to meet the requirements of the aforementioned magnification and real image imaging mode.

[0068] The lens group bracket is used to define the position of each microsphere lens in the microsphere lens group; in the present embodiment, the lens group bracket is a device used to fix the relative position of each microsphere in the microsphere lens group, which enables the entire microsphere lens group to work according to the designed spatial arrangement. Specifically, the lens group bracket can adopt any feasible support scheme, including metal or silicon wafers with holes, conical probes, optical tweezers and organic films, etc. For example, when the microsphere lens group needs to work in an air environment, concentric holes of different sizes can be prepared on the silicon wafer along the thickness direction, so that each microsphere lens in the microsphere lens group can be stuck in these set holes according to the designed interval for imaging; and when the microsphere lens group needs to work in a solid immersion environment, the ball lenses can be stacked and assembled in the PDMS colloid in an upper and lower order and heated and cured. The specific steps are as follows:

[0069] (1) depositing the top microsphere lens (top microsphere lens) in the microsphere lens group on a silicon wafer;

[0070] (2) Immersing the microsphere lens with PDMS colloid;

[0071] (3) curing the PDMS and peeling it off the silicon wafer;

[0072] (4) depositing the second layer of microsphere lenses (middle layer of microsphere lenses) of the microsphere lens group on a silicon wafer;

[0073] (5) Immersing the second layer of microsphere lenses (middle layer of microsphere lenses) with PDMS colloid;

[0074] (6) aligning the top layer microsphere lens and the second layer microsphere lens concentrically and vertically and maintaining a preset interval;

[0075] (7) curing the PDMS and peeling it off the silicon wafer; and optionally

[0076] (8) Repeat steps (4) to (7) until the designed microsphere lens group is obtained.

[0077] When a certain support scheme is adopted, the influence of the support on the numerical aperture and signal-to-noise ratio of the imaging must be weakened as much as possible. In addition, the lower surface of the lens group bracket needs to be sufficiently flat, and the upper surface of the lens group bracket also needs to be sufficiently flat, so that the CCD chip can move to the imaging surface without obstruction, that is, the upper and lower surface roughness of the lens group bracket is <1μm; in the design of the lens group bracket, preferably, the lower vertex of the first microsphere lens exceeds the lower surface of the lens group bracket or is flush with the lower surface of the lens group bracket, that is: the lower vertex of the bottom microsphere lens in the microsphere lens group needs to extend out of the lens group bracket or at least be flush with the lower surface of the lens group bracket, so that the sample can be closer to the microsphere lens group to achieve higher resolution imaging.

[0078] A photoelectric conversion device is used to collect and resolve the image formed by the microsphere lens group. In the present embodiment, the photoelectric conversion device may be a camera (CCD), hereinafter referred to as CCD; the photoelectric conversion device is also crucial to the resolution of the full microsphere optical nanomicroscope. The image of the sample to be observed magnified by the microsphere lens group will be directly projected onto the CCD chip in the form of a light field intensity distribution. Therefore, the CCD chip must be placed exactly at the position of the real image imaging surface. The image of the object can only be resolved if it is larger than the CCD pixel size. The smaller the pixel of the CCD, the higher the resolution of the microscope. In addition, the current noise, thermal noise, etc. of the CCD will also affect the resolution of the entire system.

[0079] The translation stage, lens group bracket and CCD can all be installed on a high-precision three-dimensional translation stage to adjust their relative positions to achieve better imaging effects. Changes in the sample-object distance will affect the position of the real image imaging surface. In this case, the translation stage is needed to move the CCD to the exact position of the imaging surface for imaging. In addition, environmental vibrations and temperature fluctuations will also change the relative position of the lens group bracket and the camera. In this case, the translation stage is also needed to fine-tune their relative positions to achieve the best imaging effect.

[0080] It should be noted that the methods involved in the present invention are all conventional methods in the art unless otherwise specified; the specific parameters or some commonly used reagents in the above embodiments are specific embodiments or preferred embodiments under the concept of the present invention, but are not intended to limit the present invention; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present invention.

[0081] The present invention provides a description of the imaging method of the full microsphere optical nanoscope as described in the above embodiment, as follows:

[0082] When the microscope is working, the light source will illuminate the sample first, and the light transmitted or reflected from the sample carrying the sample information will be collected by the microsphere lens group; the light signal collected by the bottom microsphere lens is transmitted and amplified by the remaining microsphere lenses, and finally directly projected onto the CCD for imaging. By utilizing the super light collection and optical transformation capabilities of the microsphere lens, samples with a size smaller than the optical diffraction limit can also be resolved by the microscope.

[0083] The technical solution of the present invention is further illustrated and described below through specific embodiments.

[0084] The first embodiment uses a micro-ball lens group composed of a double-layer ball lens, and the second embodiment uses a micro-ball lens group composed of a three-layer ball lens. The two embodiments use similar imaging device structures and device preparation methods. To simplify the description, the imaging device structures and micro-ball lens group preparation methods of the two embodiments are uniformly described here, and then the respective imaging effects are introduced.

[0085] Specifically, please refer to Figure 1The structural schematic diagram of the full microsphere optical nano microscope shown in the figure shows that the PDMS film is selected as the lens group bracket and the immersion medium. The microsphere lens group is fixed inside the PDMS film. The PDMS film has a flat surface, which is particularly convenient for adjusting the position of each component. The light source device uses an LED lighting source and adopts a transmission lighting method. The illumination light first passes through the sample, carrying the pattern information of the sample to be observed; then, the transmitted light is collected by the first microsphere lens located at the bottom of the microsphere lens group, and then is transmitted and amplified by other microsphere lenses in the microsphere lens group according to the distance from the sample; finally, the microsphere lens at the top of the microsphere lens group projects the light field pattern onto the CCD chip, and the CCD records the light field intensity distribution, which is the magnified real image of the sample to be observed. Therefore, nanoscale optical imaging can be achieved with the help of a series of microsphere lenses, and the entire process does not require the participation of macroscopic optical lenses, especially the participation of objective lenses, which greatly reduces the size and manufacturing cost of the entire device.

[0086] Figure 2 Used to demonstrate the manufacturing process of fixing the microsphere lens group inside PDMS. The microsphere lens group is prepared by stacking layer by layer from top to bottom. First, the top layer of microsphere lens (referred to as the top microsphere lens) is deposited on the silicon wafer, and then PDMS is dripped onto the silicon wafer. After the PDMS is flattened, it is placed on a hot table and heated and cured for 0.5 hours. Then, the top layer of microsphere lens fixed in PDMS is peeled off from the silicon wafer; then, the middle layer of microsphere lens of the microsphere lens group located below the top layer of microsphere lens is deposited on the silicon wafer, and PDMS is dripped onto the silicon wafer. After the PDMS is flattened, please refer to Figure 3 As shown in (a), the top layer microsphere lens just fixed in the PDMS is aligned concentrically with the middle layer microsphere lens under a microscope and the designed distance is maintained. After the two layers of PDMS are solidified into a whole, they can be peeled off from the silicon wafer and the process is repeated. Figure 2 The process 4 to 7 above can obtain a microsphere lens group with any number of layers; Figure 3 (b) is a microscope photo showing the single-layer microspheres and double-layer microspheres immersed in PDMS during the preparation process.

[0087] Example 1

[0088] In order to verify the actual imaging capability of the full microsphere nano-imaging microscope realized by the proposed experimental method, this embodiment provides a lens group consisting of a double-layer microsphere lens that was successfully prepared and used for imaging performance characterization. The microsphere lens group is composed of a barium titanate microsphere with a diameter of 220μm and a refractive index of 1.93 and a barium titanate microsphere with a diameter of 950μm and a refractive index of 1.9. The two microsphere lenses are close to each other (that is, the gap g2 between the balls is 0), and the microsphere lens group thus formed, when it is close to the sample for imaging (that is, the distance l0 between the ball and the sample is 0), it can achieve a magnification of 10 times and the top microsphere lens works in the real image imaging mode. Figure 3 (b) Microscope photos showing single-layer microspheres and double-layer microspheres immersed in PDMS during the preparation process. Next, a conventional industrial CCD was used to collect images. The pixel size of the CCD is 1.62μm. On gold-coated glass, some patterns written directly by focused ion beams were used as imaging samples. Please refer to 4(a), the minimum feature size of these patterns is 350nm. During imaging, the sample is fixed on a three-dimensional translation stage. Using the translation stage, any position of interest on the sample surface can be moved to the bottom of the microsphere lens group for imaging. The CCD is mounted on another translation stage, through which the CCD can be adjusted to the real image imaging surface of the microsphere lens group. The illumination light source is a white light LED with a central wavelength of 550nm. The sample pictures taken by this full microsphere nano-imaging microscope are shown in Figure 4 (b). The 350nm microstructure can also be clearly distinguished by the full microsphere nano microscope provided in this embodiment. The microscopic photos of this sample taken using a conventional optical microscope with 10x, 20x and 100x objective lenses are shown in Figure 4 (e)-4(g). Compare these pictures with Figure 4 (b) By comparison, it can be found that the full microsphere nanomicroscope composed of the double ball lens provided in this embodiment has better imaging effect than the traditional optical microscope with a 20x objective lens, and its resolution reaches ~0.6 times the wavelength, which is very close to the optical diffraction limit.

[0089] As mentioned above, the full microsphere optical nanoscope in the present invention has requirements on the magnification and imaging mode of the microsphere lens group in design. If the microsphere lens group cannot meet these requirements, the manufactured full microsphere optical nanoscope cannot achieve nanoscale resolution.

[0090] As a comparative experiment, two other groups of microsphere lens groups consisting of two microsphere lenses are provided for imaging. For the sake of convenience, the two microscopes consisting of two microsphere lens groups are respectively referred to as full microsphere microscope 2 and full microsphere microscope 3. The lens group in full microsphere microscope 2 is composed of a barium titanate spherical lens with a diameter of 420μm and a refractive index of ~1.9 and a barium titanate spherical lens with a diameter of 950μm and a refractive index of ~1.9. The gap g2 between the two microspheres in full microsphere microscope 2 is 0. When the full microsphere microscope 2 is close to the above-mentioned sample for imaging, that is, l0=0, the imaging result is as follows Figure 4 As shown in (c), the magnification of its lens group is only ~3 times. Due to the small magnification, the image of the 330nm tiny structure in the sample is only ~1μm after magnification, which is smaller than the size of two pixels, so these tiny structures cannot be resolved by the CCD.

[0091] The experimental results prove the importance of a sufficiently large magnification design for the present invention. The lens group in the full microsphere microscope 3 is composed of a barium titanate spherical lens with a diameter of 86 μm and a refractive index of 2.2 and a barium titanate spherical lens with a diameter of 950 μm and a refractive index of 1.9. The gap g2 between the two microspheres in the full microsphere microscope 3 is 0. Since the top microsphere in the lens group works in the virtual image imaging mode, the image of the sample will not be projected above the microsphere lens group, so the CCD cannot collect the image of the sample in the space above the microsphere lens group.

[0092] Figure 4 (d) is used to demonstrate the typical light field distribution above the microsphere lens group when the full microsphere microscope 3 is used to image the above sample. During the imaging process, the full microsphere microscope 3 is close to the imaging sample, that is, l0=0. The full microsphere microscope 2 is able to image the sample, but due to insufficient magnification, only the outline of the large pattern can be seen and its internal nanoscale structure cannot be distinguished. In contrast, since the top microsphere of the full microsphere microscope 3 does not work in the real image imaging mode, only a relatively uniform background light field can be captured in the space above the microsphere lens group without the image of the sample. These experimental results prove that designing the size and refractive index of each microsphere in the microsphere lens group so that it has a sufficiently large magnification and the top microsphere works in the real image imaging mode is a necessary condition for realizing the function of the present invention.

[0093] Example 2

[0094] In order to further improve the imaging resolution, the microsphere at the bottom of the microsphere lens group needs to have a smaller diameter. In order to maintain a longer projection distance (the distance between the imaging surface and the top of the microsphere), the top microsphere must be large enough. In this dilemma, it is difficult for a lens group consisting of two microspheres to achieve the target magnification and imaging quality. At this time, preferably, three, four or more microsphere lenses can be used to build a microsphere lens group. In order to ensure the imaging resolution and real image projection distance, the bottom and top ball lenses of the microsphere lens group respectively use a barium titanate microsphere lens with a diameter of 34μm and a refractive index of 2.2 and a barium titanate microsphere lens with a diameter of 940μm and a refractive index of 1.9. The curve of the magnification of the microsphere lens group and the projection distance calculated according to the geometric optics theory as the diameter of the second layer of microspheres (refractive index 1.9) changes is shown in Figure 5 When the diameter of the second layer of microspheres is in the range of 400μm-700μm, a larger magnification and projection distance can be maintained at the same time. Based on this, a 600μm microsphere lens is used to prepare this three-microsphere full microsphere nanomicroscope.

[0095] To verify the actual imaging capability of the full microsphere nanomicroscope composed of three layers of ball lenses, please refer to Figure 6 As shown in (a), a sample with a minimum feature size of 216nm (0.39 times the wavelength) was used for imaging characterization experiments. The sample photos taken by the full microsphere nano-imaging microscope are shown in Figure 6 In (b), the 216 nm microstructure can be obtained from Figure 6 (b) is resolved. Microscopic photographs of this sample taken using a conventional optical microscope with 10x, 20x, and 100x objectives are shown in Figure 6 (c)-6(e). Figure 6 (b) By comparison, it can be found that the imaging effect of this full-microsphere nano-imaging microscope composed of three layers of spherical lenses is slightly better than that of the traditional optical microscope with a 100x objective lens.

[0096] It can be seen that the full microsphere nano microscope provided by the present invention can resolve patterns smaller than the optical diffraction limit (0.39 times the wavelength), and its manufacturing cost is much lower than that of an ordinary optical microscope with a 100x objective lens. Therefore, it has extremely strong market competitiveness.

[0097] In addition, those skilled in the art should understand that, although there are many problems in the prior art, each embodiment or technical solution of the present invention can be improved in only one or several aspects, without having to solve all the technical problems listed in the prior art or background technology at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be used as a limitation on the claim.

[0098] Although the terms such as microsphere lens group, ball lens, light source device, lens group bracket, photoelectric conversion device, etc. are used more frequently in this article, the possibility of using other terms is not excluded. The use of these terms is only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention; the terms "first", "second", etc. (if any) in the description and claims of the embodiments of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0099] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A full microsphere optical nanomicroscope, characterized in that: include: A light source device, which is used to optically illuminate the sample to be observed; A microsphere lens assembly, which is used to collect and amplify reflected or transmitted light carrying information of the sample to be observed; A lens group bracket, which is used to define the position of each microball lens in the microball lens group; A photoelectric conversion device for collecting and resolving an image formed by the microsphere lens group; Wherein, the microball lens group includes a plurality of microball lenses, and the plurality of microball lenses are vertically stacked in a coaxial manner; The microsphere lenses are defined as the first microsphere lens, the second microsphere lens, and the i-th microsphere lens from near to far according to the distance from the sample; The distance between the imaging surface position of the microball lens group composed of k microball lenses and the vertex of the microball lens satisfies the following formula: n0 refers to the refractive index of the environment, n1 refers to the refractive index of the first microsphere lens, and n i refers to the refractive index of the i-th microsphere lens; r1 refers to the radius of the first microsphere lens, r i refers to the radius of the i-th microsphere lens; l0 refers to the distance between the sample and the lower vertex of the first microsphere lens, which takes a negative value in the calculation; l'1 refers to the distance between the imaging surface position of the first microsphere lens and the upper vertex of the first microsphere lens; l' i It refers to the distance between the imaging surface position of the i-th microsphere lens and the vertex on the corresponding microsphere lens; The distance l' between the imaging surface position of the kth microsphere lens and the vertex of the corresponding microsphere lens k is greater than 0, so that the imaging plane is located on the side of the kth microsphere lens away from the sample; The magnification β of the microsphere lens group composed of k microsphere lenses satisfies the following formula: Where β1 refers to the magnification of the first microsphere lens, β i refers to the magnification of the i-th microsphere lens, β refers to the total magnification of the entire microsphere lens group; g i It refers to the distance between the i-th microsphere lens and the i-1-th microsphere lens, which takes a negative value in the calculation.

2. The full microsphere optical nanoscope according to claim 1, characterized in that: The magnification of the microsphere lens group is greater than 8 times.

3. The full microsphere optical nanoscope according to claim 1, characterized in that: The distance between any two adjacent micro-ball lenses is the same or different, and the distance between any two adjacent micro-ball lenses is greater than or equal to 0.

4. The full microsphere optical nanoscope according to claim 1, characterized in that: The diameter of the microsphere lens is greater than 1 μm and less than 3 mm.

5. The full microsphere optical nanoscope according to claim 1, characterized in that: The diameter of the first microsphere lens is greater than 20 μm and less than 50 μm.

6. The full microsphere optical nanoscope according to claim 1, characterized in that: The upper and lower surfaces of the lens assembly bracket have a roughness of less than 1 μm.

7. The full microsphere optical nanoscope according to claim 1, characterized in that: The lower vertex of the first microsphere lens exceeds the lower surface of the lens group bracket or is flush with the lower surface of the lens group bracket.

8. The full microsphere optical nanoscope according to claim 1, characterized in that: The total magnification of the microsphere lens group meets the following conditions: β ≥ 2x / d; d refers to the size of the smallest feature to be observed on the sample to be observed, and x refers to the pixel width of the photoelectric conversion device.

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