Microscope objective and method for determining a lens group thereof

Abstract

The application discloses a microscope objective lens and a lens group determination method thereof. The objective lens comprises coaxially arranged single lenses, a focusing lens group comprising a first lens and a second lens, the first lens being a meniscus positive lens, and the second lens being a double convex aspheric lens; a chromatic aberration lens group comprising a third lens to an eighth lens, the third lens being a double convex positive lens, the fourth lens being a meniscus negative lens, the fifth lens being a meniscus negative lens, the sixth lens being a double convex positive lens, the seventh lens being a meniscus negative lens, and the eighth lens being a double convex aspheric positive lens; and a collimating lens group comprising a ninth lens and a tenth lens, the ninth lens being a meniscus positive lens, and the tenth lens being a double concave negative lens. The problem that the microscope objective lens in the prior art usually adopts a cemented lens for imaging, the cemented lens is separated in an ultralow-temperature environment, and the microscope objective lens cannot realize effective microscopic imaging in the ultralow-temperature environment is solved.

Description

Technical Field

[0001] This application relates to the field of optical imaging, and more specifically, to a microscope objective and a method for determining the lens group thereon. Background Technology

[0002] In specialized applications such as the measurement of quantum dots, one-dimensional nanowires, graphene, and two-dimensional crystal materials, microscopes need to operate at ultra-low temperatures to improve resolution, reduce noise, minimize scattering and non-radiative effects, and increase quantum efficiency.

[0003] In related technologies, conventional microscope objectives cannot meet the requirements for operation in ultra-low temperature environments. On the one hand, ultra-low temperatures cause severe deformation of the lens and structure, causing the objective parameters to deviate significantly from the design values ​​and resulting in a severe decrease in imaging quality. On the other hand, conventional microscope objectives contain cemented lenses, and the conventional optical adhesive will detach at ultra-low temperatures, causing the cemented lenses to separate. Under high vacuum conditions, this will lead to gas release, reducing the transmittance of the cemented lenses. Conventional microscope objectives require double or triple cementation to achieve good imaging results, but the optical adhesive used for cementation cannot function properly in low-temperature, high-vacuum environments.

[0004] Currently, there is no effective solution to the problem that microscope objectives in related technologies typically use cemented lenses for imaging. Cemented lenses tend to detach and separate in ultra-low temperature environments, preventing effective microscopic imaging in such conditions. Summary of the Invention

[0005] The main objective of this application is to provide a microscope objective and a method for determining the lens group thereon, in order to solve the problem that microscope objectives in the related art usually use cemented lenses for imaging, and that cemented lenses will fall off and separate in ultra-low temperature environments, resulting in the microscope objectives being unable to achieve effective microscopic imaging in ultra-low temperature environments.

[0006] To achieve the above objectives, according to one aspect of this application, a microscope objective is provided, comprising: a plurality of single lenses arranged coaxially, the plurality of single lenses including a focusing lens group for converging object-side divergent light into parallel light, a chromatic aberration lens group for achromatic purposes, and a collimating lens group for converging propagating light rays and collimating them into parallel light; the focusing lens group includes a first lens and a second lens arranged sequentially from the object side to the image side, the first lens being a meniscus positive lens with a concave surface facing the object side, and the second lens being an aspherical biconvex lens; the chromatic aberration lens group includes a third lens, a fourth lens, a fifth lens, and a sixth lens arranged sequentially from the object side to the image side. The collimating lens group includes a seventh lens, an eighth lens, and a third lens positioned behind the second lens. The third lens is a biconvex positive lens. The fourth lens is a meniscus negative lens with a concave surface facing the object. The fifth lens is a meniscus negative lens with a convex surface facing the object. The sixth lens is a biconvex positive lens. The seventh lens is a meniscus negative lens with a convex surface facing the object. The eighth lens is an aspherical biconvex positive lens. The collimating lens group includes a ninth lens and a tenth lens arranged sequentially from the object side to the image side. The ninth lens is a meniscus positive lens with a convex surface facing the object. The tenth lens is a biconcave negative lens.

[0007] Optionally, the first lens to the tenth lens are all made of glass.

[0008] Optionally, the first lens has a radius of curvature of -23.05 to -20.89 mm and a thickness of 4.03 to 4.29 mm; the second lens is an aspherical lens with a thickness of 5.13 to 5.28 mm; the ratio of the focal length of the first lens to the focal length of the microscope objective is greater than 3.46 and less than 5.42; the ratio of the focal length of the second lens to the focal length of the microscope objective is greater than 6.17 and less than 9.66.

[0009] Optionally, the first air lens formed between the first lens and the second lens has a radius of curvature of -8.75 to -7.59 mm and a thickness of 0.05 to 0.18 mm.

[0010] Optionally, the radius of curvature of the third lens is 30.21–32.04 mm, and the thickness is 4.06–4.08 mm; the radius of curvature of the fourth lens is -14.35–-12.42 mm, and the thickness is 2.82–3.03 mm; the radius of curvature of the fifth lens is 162.09–163.64 mm, and the thickness is 2.83–3.13 mm; the radius of curvature of the sixth lens is 22.22–23.69 mm, and the thickness is 5.21–5.55 mm; the radius of curvature of the seventh lens is 50.88–52.26 mm, and the thickness is 2.93–3.00 mm; and the eighth lens is an aspherical lens with a thickness of 4.00–4.22 mm.

[0011] Optionally, the second air lens formed between the third lens and the second lens has a radius of curvature of -19.72 to -18.82 mm and a thickness of 1.70 to 1.76 mm; the third air lens formed between the fourth lens and the third lens has a radius of curvature of -31.41 to -29.99 mm and a thickness of 2.72 to 2.89 mm; the fourth air lens formed between the fifth lens and the fourth lens is an aspherical lens with a thickness of 2.69 to 2.99 mm; the third... The fifth air lens formed between the sixth lens and the fifth lens has a radius of curvature of 20.99–23.71 mm and a thickness of 1.32–1.41 mm; the sixth air lens formed between the seventh lens and the sixth lens has a radius of curvature of -24.34–-23.33 mm and a thickness of 0.06–0.11 mm; the seventh air lens formed between the eighth lens and the seventh lens has a radius of curvature of 11.36–13.35 mm and a thickness of 2.43–2.68 mm.

[0012] Optionally, the radius of curvature of the ninth lens is 8.06 to 10.76 mm and the thickness is 4.93 to 5.21 mm; the radius of curvature of the tenth lens is -19.80 to -17.04 mm and the thickness is 3.90 to 4.04 mm.

[0013] Optionally, the eighth air lens formed between the ninth lens and the eighth lens has a radius of curvature of -42.71 to -40.75 mm and a thickness of 19.18 to 19.35 mm; the ninth air lens formed between the tenth lens and the ninth lens has a radius of curvature of 9.91 to 11.16 mm and a thickness of 3.28 to 3.50 mm; the tenth air lens formed on the side of the tenth lens away from the object has a radius of curvature of 9.36 to 10.46 mm and an unlimited thickness.

[0014] To achieve the above objectives, according to another aspect of this application, a method for determining the lens group of a microscope objective is provided, comprising: determining imaging parameters of the lens group according to the imaging requirements of the lens group, wherein the imaging parameters include numerical aperture and object-side field of view; determining the configuration of a focusing lens group according to the imaging parameters, wherein the focusing lens group includes a first lens and a second lens arranged sequentially from the object side to the image side, the first lens being a meniscus positive lens with a concave surface facing the object side, and the second lens being an aspherical biconvex lens; and determining the configuration of a chromatic aberration lens group for correcting chromatic aberration according to the chromatic aberration distribution of the output light of the focusing lens group, wherein the chromatic aberration lens group includes a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially from the object side to the image side. The eighth lens, the third lens is disposed behind the second lens, the third lens is a biconvex positive lens, the fourth lens is a meniscus negative lens with a concave surface facing the object, the fifth lens is a meniscus negative lens with a convex surface facing the object, the sixth lens is a biconvex positive lens, the seventh lens is a meniscus negative lens with a convex surface facing the object, and the eighth lens is an aspherical biconvex positive lens; based on the output light of the chromatic aberration lens group, the configuration of the collimating lens group for converging and collimating the propagating light into parallel light is determined, wherein the collimating lens group includes a ninth lens and a tenth lens arranged sequentially from the object side to the image side, the ninth lens is a meniscus positive lens with a convex surface facing the object, and the tenth lens is configured as a biconcave negative lens.

[0015] Optionally, the method further includes: determining the coma of the light output from the tenth lens for imaging; and adjusting the sixth lens according to the coma if the coma exceeds a preset threshold range, so that the adjusted coma does not exceed the preset threshold range.

[0016] This application describes a plurality of single lenses coaxially arranged, including a focusing lens group, a chromatic aberration lens group, and a collimating lens group. The focusing lens group includes a first lens and a second lens arranged sequentially from the object side to the image side. The first lens is a meniscus positive lens, and the second lens is an aspherical biconvex lens. The chromatic aberration lens group includes a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially from the object side to the image side. The third lens is positioned behind the second lens. The third lens is a biconvex positive lens, the fourth lens is a meniscus negative lens, the fifth lens is a meniscus negative lens, the sixth lens is a biconvex positive lens, the seventh lens is a meniscus negative lens, and the eighth lens is an aspherical biconvex positive lens. The collimating lens group includes a ninth lens and a tenth lens arranged sequentially from the object side to the image side. The ninth lens is a meniscus positive lens, and the tenth lens is a biconcave negative lens. By employing a lens group composed of multiple single lenses, the system can function normally even in ultra-low temperature environments. It also achieves apochromatic effects and improves imaging quality. This solves the problem that microscope objectives typically use cemented lenses for imaging, which can detach and separate in ultra-low temperature environments, preventing effective microscopic imaging in such conditions. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0018] Figure 1 This is a schematic diagram of a lens assembly for a microscope objective provided according to an embodiment of this application;

[0019] Figure 2 This is a schematic diagram of the 0° field-of-view ray aberration curve of a microscope objective lens provided according to an embodiment of this application;

[0020] Figure 3 This is a schematic diagram of the 0° field-of-view wavefront aberration curve of a microscope objective provided according to an embodiment of this application;

[0021] Figure 4 This is a schematic diagram of the MTF curve of a microscope objective lens provided according to an embodiment of this application;

[0022] Figure 5 This is a schematic diagram of the axial aberration curve of a microscope objective lens provided according to an embodiment of this application;

[0023] Figure 6 This is a schematic diagram of the field curvature distortion of a microscope objective lens provided according to an embodiment of this application;

[0024] Figure 7This is a flowchart of a method for determining the lens group of a microscope objective according to an embodiment of this application. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] The technical solution of this application will be described below with reference to specific implementation methods. Figure 1 This is a schematic diagram of a lens assembly for a microscope objective provided according to an embodiment of this application, such as... Figure 1 As shown, the microscope objective includes: a plurality of single lenses arranged coaxially, the plurality of single lenses including a focusing lens group for converging object-side divergent light into parallel light, a chromatic aberration lens group for achromatic light, and a collimating lens group for converging propagating light and collimating it into parallel light.

[0029] The focusing lens group includes a first lens L1 and a second lens L2 arranged sequentially from the object side to the image side. The first lens L1 is a meniscus positive lens with a concave surface facing the object side, and the second lens L2 is an aspherical biconvex lens.

[0030] The chromatic aberration lens group includes a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8 arranged sequentially from the object side to the image side. The third lens L3 is positioned behind the second lens L2. The third lens L3 is a biconvex positive lens. The fourth lens L4 is a meniscus negative lens with a concave surface facing the object side. The fifth lens L5 is a meniscus negative lens with a convex surface facing the object side. The sixth lens L6 is a biconvex positive lens. The seventh lens L7 is a meniscus negative lens with a convex surface facing the object side. The eighth lens L8 is an aspherical biconvex positive lens.

[0031] The collimating lens group includes a ninth lens L9 and a tenth lens L10 arranged sequentially from the object side to the image side. The ninth lens L9 is a meniscus positive lens with a convex surface facing the object side, and the tenth lens L10 is a double concave negative lens.

[0032] By coaxially arranging the ten single lenses mentioned above, the observed object located on the object plane is magnified and imaged, and the image output by the objective lens ensures a large field of view while having high resolution. Furthermore, the combination of the lenses effectively corrects aberrations and chromatic aberrations caused by imaging.

[0033] The combination of multiple single lenses ensures that the deformation of a single lens will not affect other lenses in ultra-low temperature environments, thus achieving normal operation even in ultra-low temperature working environments. At the same time, it realizes the technical effect of apochromatic and improves imaging quality. This solves the problem that microscope objectives usually use cemented lenses for imaging, and cemented lenses will detach and separate in ultra-low temperature environments, making it impossible for microscope objectives to achieve effective microscopic imaging in ultra-low temperature environments.

[0034] The aforementioned focusing lens group includes a first lens L1 and a second lens L2 arranged sequentially from the object side to the image side. The first lens L1 is a meniscus positive lens with a concave surface facing the object side, and the second lens L2 is an aspherical biconvex lens. The first lens L1 and the second lens L2 mainly provide optical power for the entire lens group, converging diverging light rays from the object side into parallel light.

[0035] The first lens L1 is primarily used to provide positive optical power, and also provides positive spherical aberration, negative coma, positive field curvature, and negative axial chromatic aberration. The second lens L2 is primarily used to provide positive optical power, and also provides positive spherical aberration, negative coma, and negative axial chromatic aberration. The ratio of the focal length of the first lens to the focal length of the microscope objective is greater than 3.46 and less than 5.42; the ratio of the focal length of the second lens to the focal length of the microscope objective is greater than 6.17 and less than 9.66. This ensures that diverging light rays from the object side are converged into parallel light.

[0036] The aforementioned chromatic aberration lens group includes, sequentially arranged from the object side to the image side, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. Lenses L3, L6, and L8 are made of high Abbe number (dispersion coefficient) and low refractive index material, and serve as positive lenses in the lens group. Lenses L4, L5, and L7 are made of high refractive index and low Abbe number material, and serve as negative lenses in the lens group. Lenses L3, L4, L5, L6, L7, and L8 meet the achromatic requirements and are primarily used to correct chromatic aberration throughout the entire lens group.

[0037] The third lens L3 is positioned behind the second lens L2. Lens L3 is a biconvex positive lens, providing positive optical power, positive spherical aberration, positive coma, and negative axial chromatic aberration. The fourth lens L4 is a meniscus negative lens with a concave surface facing the object, providing negative optical power, negative spherical aberration, negative coma, and positive axial chromatic aberration. The fifth lens L5 is a meniscus negative lens with a convex surface facing the object, providing negative optical power, negative spherical aberration, positive coma, negative astigmatism, positive axial chromatic aberration, and negative transverse chromatic aberration. The sixth lens L6 is a biconvex positive lens, providing positive optical power, positive spherical aberration, negative coma, positive astigmatism, and negative axial chromatic aberration. The seventh lens L7 is a meniscus negative lens with a convex surface facing the object, providing negative optical power, negative spherical aberration, positive coma, negative astigmatism, positive axial chromatic aberration, and negative transverse chromatic aberration. The eighth lens, L8, is an aspherical biconvex positive lens that provides positive optical power, as well as positive spherical aberration, negative coma, positive astigmatism, and negative axial chromatic aberration.

[0038] The collimating lens group mentioned above includes a ninth lens L9 and a tenth lens L10 arranged sequentially from the object side to the image side. The ninth lens L9 is made of a high refractive index material to shrink the light beam and shorten the overall length of the lens group. The tenth lens L10 is a negative lens used to collimate the converging light beam that has passed through the ninth lens L9 into parallel light.

[0039] The ninth lens, L9, is a meniscus positive lens with a convex surface facing the object side. It provides positive optical power and also provides positive spherical aberration, negative coma, positive astigmatism, negative distortion, negative axial chromatic aberration, and positive transverse chromatic aberration. The tenth lens, L10, is a biconcave negative lens that provides negative optical power and also provides negative spherical aberration, positive coma, negative astigmatism, negative field curvature, positive distortion, and positive axial chromatic aberration.

[0040] The first to tenth lenses constitute a lens group, with a numerical aperture ranging from 0.6 to 0.7. The object-side field of view of this cryogenic microscope objective is 0.1 to 0.6 mm. The distance between the first lens and the object-side sample is greater than 2 mm. Within the 600-750 nm wavelength range, the chromatic focus shift is less than λ / NA², achieving apochromatic aberration. It corrects spherical aberration, coma, astigmatism, field curvature, distortion, axial chromatic aberration, and magnification chromatic aberration, meeting the plan-field apochromatic aberration standard.

[0041] Optionally, all tenth lenses may be made of glass. Glass has good light transmittance in ultra-low temperature environments, and it also has small deformation and high hardness, making it suitable for use in ultra-low temperature environments.

[0042] Optionally, the first lens has a radius of curvature of -23.05 to -20.89 mm and a thickness of 4.03 to 4.29 mm; the second lens is an aspherical lens with a thickness of 5.13 to 5.28 mm; the ratio of the focal length of the first lens to the focal length of the microscope objective is greater than 3.46 and less than 5.42; the ratio of the focal length of the second lens to the focal length of the microscope objective is greater than 6.17 and less than 9.66.

[0043] Optionally, the first air lens formed between the first lens and the second lens has a radius of curvature of -8.75 to -7.59 mm and a thickness of 0.05 to 0.18 mm.

[0044] Only by setting the first and second lenses according to the above-mentioned radius of curvature and thickness can the object surface that reaches the preset object-side field of view be magnified in the above-mentioned lens group, ensuring that the lens group has a large object-side field of view.

[0045] Optionally, the radius of curvature of the third lens is 30.21–32.04 mm, and the thickness is 4.06–4.08 mm; the radius of curvature of the fourth lens is -14.35–-12.42 mm, and the thickness is 2.82–3.03 mm; the radius of curvature of the fifth lens is 162.09–163.64 mm, and the thickness is 2.83–3.13 mm; the radius of curvature of the sixth lens is 22.22–23.69 mm, and the thickness is 5.21–5.55 mm; the radius of curvature of the seventh lens is 50.88–52.26 mm, and the thickness is 2.93–3.00 mm; and the eighth lens is an aspherical lens with a thickness of 4.00–4.22 mm.

[0046] Optionally, the second air lens formed between the third lens and the second lens has a radius of curvature of -19.72 to -18.82 mm and a thickness of 1.70 to 1.76 mm; the third air lens formed between the fourth lens and the third lens has a radius of curvature of -31.41 to -29.99 mm and a thickness of 2.72 to 2.89 mm; the fourth air lens formed between the fifth lens and the fourth lens is an aspherical lens with a thickness of 2.69 to 2.99 mm; the fifth air lens formed between the sixth lens and the fifth lens has a radius of curvature of 20.99 to 23.71 mm and a thickness of 1.32 to 1.41 mm; the sixth air lens formed between the seventh lens and the sixth lens has a radius of curvature of -24.34 to -23.33 mm and a thickness of 0.06 to 0.11 mm; and the seventh air lens formed between the eighth lens and the seventh lens has a radius of curvature of 11.36 to 13.35 mm and a thickness of 2.43 to 2.68 mm.

[0047] Only by setting the third to eighth lenses according to the above-mentioned radius of curvature and thickness can various aberrations, such as spherical aberration and coma, be effectively eliminated in the above lens group. At the same time, while correcting phase aberration, chromatic aberration caused by aberration correction will also be corrected to ensure that the image output by the lens group has the required phase aberration, and in the process of phase aberration correction, the influence on the corrected chromatic aberration should be avoided as much as possible.

[0048] It should be noted that during the lens assembly and adjustment process, coma can be adjusted by adjusting the sixth lens.

[0049] Optionally, the radius of curvature of the ninth lens is 8.06–10.76 mm and the thickness is 4.93–5.21 mm; the radius of curvature of the tenth lens is -19.80–-17.04 mm and the thickness is 3.90–4.04 mm.

[0050] Optionally, the eighth air lens formed between the ninth and eighth lenses has a radius of curvature of -42.71 to -40.75 mm and a thickness of 19.18 to 19.35 mm; the ninth air lens formed between the tenth and ninth lenses has a radius of curvature of 9.91 to 11.16 mm and a thickness of 3.28 to 3.50 mm; and the tenth air lens formed on the side of the tenth lens away from the object has a radius of curvature of 9.36 to 10.46 mm and an unlimited thickness.

[0051] Only by setting the ninth to tenth lenses according to the above-mentioned radius of curvature and thickness can the light output from the eighth lens be effectively converged in the above lens group, ensuring that the image formed by the light output from the tenth lens meets the requirements.

[0052] It should be noted that this application also provides an optional implementation method, which will be described in detail below.

[0053] To address the shortcomings of existing technologies, a microscope objective suitable for ultra-low temperature and high vacuum conditions is provided. This microscope objective is free of cemented lenses, meeting the requirements for operation in ultra-low temperature (≥0.1K) environments. Furthermore, this microscope objective possesses advantages such as field flatness, apochromaticity, and excellent imaging performance. The numerical aperture of this microscope objective is 0.6-0.7 mm, the object-side field of view is 0-0.6 mm, and the chromatic focus shift is less than λ / NA² in the 600-750 nm wavelength range. It achieves apochromaticity and corrects spherical aberration, coma, astigmatism, field curvature, distortion, axial chromatic aberration, and magnification chromatic aberration, meeting the field flat apochromaticity standard.

[0054] This microscope objective consists entirely of single-lens lenses. Starting from the object side, the first lens, second lens, ..., tenth lens are arranged sequentially. The first and second lenses primarily provide optical power; the third through eighth lenses mainly correct chromatic aberration; the ninth lens mainly reduces the beam from the eighth lens; and the tenth lens mainly collimates and converges the beam. This microscope objective does not use cemented lenses; all lenses are single-lens, achieving apochromatic effect. The cavities between adjacent lenses are filled with air, forming an air lens. Specific parameters are shown in Table 1, which is a parameter table for each lens element of the microscope objective.

[0055] Table 1. Parameters of each lens element of the microscope objective.

[0056]

[0057] The first lens L1 is a meniscus positive lens providing positive optical power, with a concave surface facing the object plane; the second lens L2 is a biconvex positive lens providing positive optical power; the third lens L3 is a biconvex positive lens providing positive optical power; the fourth lens L4 is a meniscus negative lens providing negative optical power, with a concave surface facing the object plane; the fifth lens L5 is a meniscus negative lens providing negative optical power, with a convex surface facing the object plane; the sixth lens L6 is a biconvex positive lens providing positive optical power; the seventh lens L7 is a meniscus negative lens providing negative optical power, with a convex surface facing the object plane; the eighth lens L8 is a biconvex positive lens providing positive optical power; the ninth lens L9 is a meniscus positive lens providing positive optical power, with a convex surface facing the object plane; and the tenth lens L10 is a biconcave negative lens providing negative optical power.

[0058] The first lens L1 provides positive spherical aberration, negative coma, positive field curvature, and negative axial chromatic aberration; the second lens L2 primarily provides positive spherical aberration, negative coma, and negative axial chromatic aberration; the third lens L3 primarily provides positive spherical aberration, positive coma, and negative axial chromatic aberration; the fourth lens L4 primarily provides negative spherical aberration, negative coma, and positive axial chromatic aberration; the fifth lens L5 primarily provides negative spherical aberration, positive coma, negative astigmatism, positive axial chromatic aberration, and negative transverse chromatic aberration; the sixth lens L6 primarily provides positive spherical aberration, negative coma, positive astigmatism, and negative axial chromatic aberration. Chromatic aberration; The seventh lens L7 is set as a meniscus negative lens with a convex surface facing the object plane, mainly providing negative spherical aberration, positive coma, negative astigmatism, positive axial chromatic aberration, and negative transverse chromatic aberration; The eighth lens L8 mainly provides positive spherical aberration, negative coma, positive astigmatism, and negative axial chromatic aberration; The ninth lens L9 mainly provides positive spherical aberration, negative coma, positive astigmatism, negative distortion, negative axial chromatic aberration, and positive transverse chromatic aberration; The tenth lens L10 mainly provides negative spherical aberration, positive coma, negative astigmatism, negative field curvature, positive distortion, and positive axial chromatic aberration.

[0059] The imaging effect of this microscope objective is analyzed below.

[0060] Figure 2 This is a schematic diagram of the 0° field-of-view ray aberration curve of a microscope objective lens provided according to an embodiment of this application, as shown below. Figure 2 As shown, Figure 2 In the graph, the horizontal axes Py and Px represent the normalized pupil position, and the vertical axes ey and ex represent the transverse aberration. The maximum value of the vertical axis is 2µm, and the minimum value is -2µm. The curve on the left corresponds to the meridional aberration curve of the beam, and the curve on the right corresponds to the sagittal aberration curve of the beam. Figure 2 The aberration curves for different gray levels correspond to wavelengths of 750nm, 713nm, 675nm, 637nm, and 600nm, respectively. Figure 2 Within the pupil range of 0.9 to 1.0, the light aberration value is between ±0.4 and ±1 μm, and within the pupil range of 0 to 0.9, the light aberration value is between 0 and ±0.4 μm. The overall aberration value is small, and the imaging quality is excellent.

[0061] Figure 3 This is a schematic diagram of the 0° field-of-view wavefront aberration curve of a microscope objective provided according to an embodiment of this application, as shown below. Figure 3 As shown, Figure 3 In the graph, the horizontal axes Py and Px represent the normalized pupil position, and the vertical axis w represents the wavefront aberration. The maximum value of the vertical axis is 0.5 times the wavelength, and the minimum value is -0.5 times the wavelength. The curve on the left corresponds to the meridional wavefront aberration curve of the beam, and the curve on the right corresponds to the sagittal wavefront aberration curve of the beam. Figure 3Wavefront aberration curves of different gray levels correspond to wavelengths of 750nm, 713nm, 675nm, 637nm, and 600nm, respectively. The optical path difference within the 0.7–1.0 pupil range is between ±0.1 and ±0.25 times the wavelength, while the optical aberration within the 0–0.7 pupil range is between 0 and ±0.1 wavelengths. Overall, the optical path difference is relatively small.

[0062] Figure 4 This is a schematic diagram of the MTF curve of a microscope objective lens provided according to an embodiment of this application, such as... Figure 4 As shown, Figure 4 The horizontal axis represents the spatial frequency in line pairs per millimeter, and the vertical axis represents the OTF modulus, which is the modulation transfer function (MTF). The MTF curve is greater than 0.6 at 440 lp / mm, greater than 0.35 at 880 lp / mm, and greater than 0.17 at 1320 lp / mm, generally close to the diffraction limit, indicating good image quality.

[0063] Figure 5 This is a schematic diagram of the axial aberration curve of a microscope objective lens provided according to an embodiment of this application, such as... Figure 5 As shown, Figure 5 The horizontal axis represents the axial aberration of the lens group, measured in mm, while the vertical axis represents the normalized pupil coordinates. Figure 5 The wavefront aberration curves of different gray levels correspond to wavelengths of 750nm, 713nm, 675nm, 637nm, and 600nm, respectively. The maximum axial chromatic aberration value of 1.527µm is found at the 1.0 times pupil position, which is less than λ / NA², satisfying the apochromatic condition.

[0064] Figure 6 This is a schematic diagram of the field curvature distortion of a microscope objective lens provided according to an embodiment of this application, as shown below. Figure 6 As shown, Figure 6 The left-middle figure is the field curvature plot. The horizontal axis represents the field curvature value in µm, and the vertical axis represents the field of view in °. The left figure shows the field curvature curve at a wavelength of 675 nm, satisfying (τ... s +τ t ) / 2≈0.6um<λ / (2NA 2 ) and |τ s -τ t |≈0.2um<λ / (2NA 2 The condition of τ is met, thus achieving the requirement of a level field. In the formula, τ s For the opening theme, τ t The figure shows the final field curve, where λ is the wavelength and NA is the numerical aperture. The horizontal axis of the right figure represents the percentage of distortion, and the vertical axis represents the field of view, in degrees (°). The right figure shows the distortion curve at a wavelength of 675 nm, with the maximum distortion at the edge of the field of view being <1.1%.

[0065] Therefore, the microscope objective provided in this embodiment is suitable for ultra-low temperature and high vacuum conditions. At ultra-low temperatures, conventional optical adhesives will detach, severely affecting the use of cemented lenses. At high vacuum, conventional optical adhesives will begin to release gas, causing the adhesive layer to become cloudy and opaque, severely affecting the light transmittance of the lens assembly. The characteristic of this patent is that this microscope objective is composed entirely of a single lens, without using cemented lenses, thus avoiding the problems of optical adhesive detachment and gas release, and achieving ultra-low temperature and high vacuum microscopic imaging.

[0066] Of course, the microscope objective lens of this embodiment, suitable for ultra-low temperature and high vacuum, can also have various transformations and modifications, and is not limited to the specific structure of the above-described embodiment. In short, the scope of protection of this invention should include those transformations, substitutions, and modifications that are obvious to those skilled in the art.

[0067] To achieve the above objectives, according to another aspect of this application, a method for determining the lens group of a microscope objective is provided. The invention will now be described in conjunction with preferred embodiments. Figure 7 This is a flowchart of a method for determining the lens group of a microscope objective according to an embodiment of this application, as shown below. Figure 7 As shown, the method includes the following steps:

[0068] Step S701: Determine the imaging parameters of the lens group according to the imaging requirements of the lens group, wherein the imaging parameters include numerical aperture and object-side field of view.

[0069] Step S702: Determine the configuration of the focusing lens group according to the imaging parameters. The focusing lens group includes a first lens and a second lens arranged sequentially from the object side to the image side. The first lens is a meniscus positive lens with a concave surface facing the object side, and the second lens is an aspherical biconvex lens.

[0070] Step S703: Based on the chromatic aberration distribution of the output light from the focusing lens group, determine the configuration of the chromatic aberration lens group used to correct chromatic aberration. The chromatic aberration lens group includes a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially from the object side to the image side. The third lens is located behind the second lens and is a biconvex positive lens. The fourth lens is a meniscus negative lens with a concave surface facing the object side. The fifth lens is a meniscus negative lens with a convex surface facing the object side. The sixth lens is a biconvex positive lens. The seventh lens is a meniscus negative lens with a convex surface facing the object side. The eighth lens is an aspherical biconvex positive lens.

[0071] Step S704: Based on the output light of the chromatic aberration lens group, determine the configuration of the collimating lens group used to converge the propagating light and collimate it into parallel light. The collimating lens group includes a ninth lens and a tenth lens arranged sequentially from the object side to the image side. The ninth lens is a meniscus positive lens with a convex surface facing the object side, and the tenth lens is a double concave negative lens.

[0072] The above steps utilize multiple single lenses arranged coaxially. These single lenses include a focusing lens group, a chromatic aberration lens group, and a collimating lens group. The focusing lens group includes a first lens and a second lens arranged sequentially from the object side to the image side. The first lens is a meniscus positive lens, and the second lens is an aspherical biconvex lens. The chromatic aberration lens group includes a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially from the object side to the image side. The third lens is positioned behind the second lens. The third lens is a biconvex positive lens, the fourth lens is a meniscus negative lens, the fifth lens is a meniscus negative lens, the sixth lens is a biconvex positive lens, the seventh lens is a meniscus negative lens, and the eighth lens is an aspherical biconvex positive lens. The collimating lens group includes a ninth lens and a tenth lens arranged sequentially from the object side to the image side. The ninth lens is a meniscus positive lens, and the tenth lens is a biconcave negative lens. By employing a lens group composed of multiple single lenses, the system can function normally even in ultra-low temperature environments. It also achieves apochromatic effects and improves imaging quality. This solves the problem that microscope objectives typically use cemented lenses for imaging, which can detach and separate in ultra-low temperature environments, preventing effective microscopic imaging in such conditions.

[0073] The above configuration includes the number and shape of lenses, as well as the position and distance of each lens.

[0074] Optionally, the method further includes: determining the coma of the light output from the tenth lens for imaging; and adjusting the sixth lens according to the coma if the coma exceeds a preset threshold range, so that the adjusted coma does not exceed the preset threshold range.

[0075] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0076] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A microscope objective lens, characterized in that, include: A focusing lens group for converging object-side divergent light into parallel light, a chromatic aberration lens group for achromatic light, and a collimating lens group for converging propagating light and refracting it into parallel light. The focusing lens group consists of a first lens and a second lens arranged sequentially from the object side to the image side. The first lens is a meniscus positive lens with a concave surface facing the object side, and the second lens is an aspherical biconvex lens. The chromatic aberration lens group consists of a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially from the object side to the image side. The third lens is positioned behind the second lens and is a biconvex positive lens. The fourth lens is a meniscus negative lens with a concave surface facing the object side. The fifth lens is a meniscus negative lens with a convex surface facing the object side. The sixth lens is a biconvex positive lens. The seventh lens is a meniscus negative lens with a convex surface facing the object side. The eighth lens is an aspherical biconvex positive lens. The collimating lens group consists of a ninth lens and a tenth lens arranged sequentially from the object side to the image side. The ninth lens is a meniscus positive lens with a convex surface facing the object side, and the tenth lens is a biconcave negative lens. The first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens, and tenth lens are single lenses arranged coaxially; The object-side radius of curvature of the first lens is -23.05 to -20.89 mm, and its thickness is 4.03 to 4.29 mm. The second lens is an aspherical lens with a thickness of 5.13~5.28mm; The ratio of the focal length of the first lens to the focal length of the microscope objective is greater than 3.46 and less than 5.42; The ratio of the focal length of the second lens to the focal length of the microscope objective is greater than 6.17 and less than 9.66; The object-side radius of curvature of the third lens is 30.21~32.04mm, and its thickness is 4.06~4.08mm; The fourth lens has an object-side radius of curvature of -14.35 to -12.42 mm and a thickness of 2.82 to 3.03 mm. The fifth lens has an object-side radius of curvature of 162.09~163.64 mm and a thickness of 2.83~3.13 mm. The object-side radius of curvature of the sixth lens is 22.22~23.69mm, and its thickness is 5.21~5.55mm; The seventh lens has an object-side radius of curvature of 50.88~52.26mm and a thickness of 2.93~3.00mm; The eighth lens is an aspherical lens with a thickness of 4.00~4.22mm; The object-side radius of curvature of the ninth lens is 8.06~10.76mm, and its thickness is 4.93~5.21mm; The object-side radius of curvature of the tenth lens is -19.80 to -17.04 mm, and its thickness is 3.90 to 4.04 mm.

2. The microscope objective according to claim 1, characterized in that, The first lens through the tenth lens are all made of glass.

3. The microscope objective according to claim 2, characterized in that, The first air lens formed between the first lens and the second lens has an object-side radius of curvature of -8.75 to -7.59 mm and a thickness of 0.05 to 0.18 mm.

4. The microscope objective according to claim 3, characterized in that, The second air lens formed between the third lens and the second lens has an object-side radius of curvature of -19.72 to -18.82 mm and a thickness of 1.70 to 1.76 mm. The third air lens formed between the fourth lens and the third lens has an object-side radius of curvature of -31.41 to -29.99 mm and a thickness of 2.72 to 2.89 mm. The fourth air lens formed between the fifth lens and the fourth lens is an aspherical lens with a thickness of 2.69~2.99mm; The fifth air lens formed between the sixth lens and the fifth lens has an object-side radius of curvature of 20.99~23.71mm and a thickness of 1.32~1.41mm. The sixth air lens formed between the seventh lens and the sixth lens has an object-side radius of curvature of -24.34 to -23.33 mm and a thickness of 0.06 to 0.11 mm. The seventh air lens formed between the eighth lens and the seventh lens has an object-side radius of curvature of 11.36~13.35mm and a thickness of 2.43~2.68mm.

5. The microscope objective according to claim 4, characterized in that, The eighth air lens formed between the ninth lens and the eighth lens has an object-side radius of curvature of -42.71 to -40.75 mm and a thickness of 19.18 to 19.35 mm. The ninth air lens formed between the tenth lens and the ninth lens has an object-side radius of curvature of 9.91~11.16mm and a thickness of 3.28~3.50mm. The tenth air lens formed on the side away from the object plane by the tenth lens has an object plane radius of curvature of 9.36~10.46mm and an unlimited thickness.

6. A method for determining the lens group of a microscope objective lens according to any one of claims 1-5, characterized in that, include: Based on the imaging requirements of the lens group, the imaging parameters of the lens group are determined, wherein the imaging parameters include numerical aperture and object-side field of view. The configuration of the focusing lens group is determined based on the imaging parameters; Based on the chromatic aberration distribution of the output light from the focusing lens group, determine the configuration of the chromatic aberration lens group used to correct the chromatic aberration; Based on the output light of the chromatic aberration lens group, determine the configuration of the collimating lens group used to converge the propagating light and refract it into parallel light.

7. The method according to claim 6, characterized in that, The method further includes: Determine the coma of the light output from the tenth lens for imaging; If the coma exceeds a preset threshold range, the sixth lens is adjusted according to the coma to ensure that the adjusted coma does not exceed the preset threshold range.

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