A large object field, long working distance microscope objective system and method

Abstract

The present application relates to the field of optical imaging technology, in particular to a large object field of view, long working distance microscope objective system and method. The microscope objective system comprises twenty optical lenses arranged on the same optical axis, two solution layers and a cover glass, and a relay group and an objective lens are sequentially arranged from the object side to the image side. For the first time, the combination of large object field of view (diameter 7.5mm~8.5mm), long working distance (7.5mm~8.5mm), high collection numerical aperture (0.9~1.1) and 0.5~0.6 numerical aperture is realized, the technical contradiction that the traditional objective lens long working distance sacrifices resolution and the large field of view is difficult to consider high collection efficiency is solved, and the demand for fine structure analysis of single neuron and dendritic spine level is met.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and more specifically, to a microscope objective system and method with a large objective field of view and a long working distance. Background Technology

[0002] In neuroscience research, mouse models are a core tool for revealing the mysteries of brain structure and function. With the rapid development of technologies such as brain connectomics, in vivo neuronal imaging, and optogenetic intervention, existing microscope objectives are increasingly revealing key technical bottlenecks in mouse brain research regarding imaging range, working distance, and imaging modalities. First, the limited sample imaging range of traditional objectives contradicts the demands of neuroscience research for whole-brain or large-scale brain region observation. For example, when mapping neuronal projections in whole-brain slices, conventional objectives have a small field of view, requiring extensive and tedious slice stitching, which is not only extremely inefficient but also prone to damaging the integrity of neural circuits due to mechanical displacement and image registration errors. This severely restricts the development of high-throughput, systematic brain science research. Secondly, in critical in vivo imaging and live manipulation scenarios, the working distance of the objective lens becomes a decisive factor. On the one hand, when observing deep brain regions (such as the hippocampus) of anesthetized or awake mice, the tip of the objective lens must pass through the cranial window, cerebrospinal fluid, or implanted glass slide. A long working distance is a prerequisite for ensuring physical space and safety. On the other hand, when combining multimodal experiments such as optogenetic stimulation and extracellular electrophysiological recording, sufficient space needs to be reserved for manipulation tools such as microelectrodes and optical fibers. Existing long working distance objectives generally sacrifice numerical aperture and imaging resolution, making it difficult to meet the needs of fine structural analysis at the level of single neurons or even dendritic spines. Furthermore, the importance of infrared imaging capabilities is becoming increasingly prominent. The near-infrared band has deeper penetration and weaker scattering characteristics in biological tissues, making it a key window for in vivo functional imaging of deep brain regions (such as two-photon excitation). However, existing objectives are not well optimized for this band, resulting in problems such as low transmittance and imperfect chromatic aberration correction, which limit the sensitivity and signal-to-noise ratio of deep high-resolution imaging.

[0003] Current technology lacks a microscope objective that can simultaneously meet the requirements of a large objective field of view, a long working distance, and a high numerical aperture to adapt to in vivo multimodal experiments, and optimize the near-infrared band to support deep functional imaging. Therefore, a microscope objective system and method with a large objective field of view and a long working distance are proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a microscope objective system and method with a large field of view and a long working distance, which solves the problems of small imaging field of view, short working distance, small collection numerical aperture and poor imaging performance in the near-infrared band in the prior art, and achieves a combination of large field of view, long working distance and high collection efficiency, so as to meet the needs of deep high-resolution imaging and multimodal experiments in the field of neuroscience.

[0005] To solve the above-mentioned technical problems, one of the objectives of this invention is to provide a microscope objective system with a large objective field of view and a long working distance, comprising a microscope objective system including twenty optical lenses arranged coaxially, two solution layers and a coverslip, with relay groups and objectives arranged sequentially from the object side to the image side. The relay group includes the G1 lens group and the G2 lens group; The G1 lens group consists of, from the object side to the image side, plane S1, lens L1, lens L2, lens L3, lens L4, lens L5, lens L6, and plane S2. The G2 lens group consists of surface S2, lens L7, lens L8, lens L9, lens L10, lens L11, and surface S3, from the object side to the image side. The objective lenses, from the object side to the image side, are as follows: plane S3, lens L12, lens L13, lens L14, lens L15, lens L16, lens L17, lens L18, lens L19, lens L20, solution layer L21, coverslip L22, and solution layer L23.

[0006] As a further improvement to this technical solution, surface S2 is a common surface of lens group G1 and lens group G2, and surface S3 is the connecting surface between relay group and objective lens.

[0007] As a further improvement to this technical solution, surface S1 is an aperture stop; lens L1 is a negative power lens, with a concave object side and a convex image side; lens L2 and lens L3 form the first group of positive power cemented lenses, with lens L2 having a concave object side and a concave image side, and lens L3 having a convex image side; lens L4 and lens L5 form the second group of positive power cemented lenses, with lens L4 having a convex object side and a concave image side, and lens L5 having a concave image side; lens L6 is a negative power lens. Lens: concave on the object side and convex on the image side; surface S2 is the focal plane of parallel light after passing through lens group G1; lens L7 is a positive power lens, concave on the object side and convex on the image side; lenses L8 and L9 form a negative power cemented lens, with lens L8 having a convex object side and a convex image side, and lens L9 having a concave image side; lens L10 is a positive power lens, convex on the object side and concave on the image side; lens L11 is a negative power lens, convex on the object side and concave on the image side.

[0008] As a further improvement to this technical solution, the aforementioned surface S3 is a common surface of the objective lens and the relay group, and the image-side surface of L23 is the surface on which the sample is placed when the microscope objective lens system is actually used, i.e., the object side.

[0009] As a further improvement to this technical solution, lens L12 is a negative power lens with a convex object side and a concave image side; lenses L13, L14, L15, L17, L18, L19, and L20 are all positive power lenses, and lens L16 is a negative power lens; lenses L13 and L14 have convex object sides and image sides, lenses L15, L17, L18, and L19 have convex object sides and concave image sides, lens L16 has concave object sides and image sides, and lens L20 has a convex object side and a flat image side.

[0010] As a further improvement to this technical solution, the focal length of the lens L12 and the focal length of the objective lens satisfy: -0.25 < <-0.24; The focal length of lens L13 and the focal length of the objective lens satisfy: 0.26 < <0.28; The focal length of lens L14 and the focal length of the objective lens satisfy: 0.19 < <0.20; The focal length of lens L15 and the focal length of the objective lens satisfy: 0.43 < <0.44; The focal length of lens L16 and the focal length of the objective lens satisfy: -1.2 < <-1.1; The focal length of lens L17 and the focal length of the objective lens satisfy: 0.30 < <0.40; The focal length of lens L18 and the focal length of the objective lens satisfy: 0.50 < <0.60; The focal length of lens L19 and the focal length of the objective lens satisfy: 0.30 < <0.40; The focal length of lens L20 and the focal length of the objective lens satisfy: 0.70 < <0.80; in, f The focal length of the objective lens. The focal length of lens L12 The focal length of lens L13. This is the focal length of lens L14. This is the focal length of lens L15. This is the focal length of lens L16. This is the focal length of lens L17. This is the focal length of lens L18. This is the focal length of lens L19. This is the focal length of lens L20.

[0011] As a further improvement to this technical solution, the above-mentioned solution layers L21 and L23 are working medium layers, and the working distance of the above-mentioned objective lens is 7.5mm~8.5mm, which is the distance from the image side of lens L20 to the image side of lens L23.

[0012] As a further improvement to this technical solution, the numerical aperture of the microscope objective system is 0.5~0.6, the collection numerical aperture is 0.9~1.1, and the final imaging surface diameter is 7.5mm~8.5mm. This final imaging surface is the surface on which the sample is placed during actual use, i.e., the object side.

[0013] As a further improvement to this technical solution, the effective focal length of the G1 lens group is 100mm, and the effective focal length of the G2 lens group is 225mm. The combination of G1 and G2 achieves a beam expansion of 2.25 times. The distance between the surface S2 and the object side of the lens L7 is 260mm. Within this distance range, external optical modulation elements and beam splitters can be placed.

[0014] The second objective of this invention is to provide a method for using a microscope objective lens with a large field of view and a long working distance, for use in any of the above-mentioned microscope objective lens systems with a large field of view and a long working distance, comprising the following steps: S1. Parallel incident light in the near-infrared band of 920nm~940nm is introduced into the relay group aperture S1 of the microscope objective system. After the aperture is adjusted, the light is incident on the G1 lens group. Through the synergistic effect of the negative optical power lens and the two positive optical power cemented lenses in the G1 lens group, the parallel light is focused to the focal plane S2 to complete the initial aberration correction. The beam at focal plane S2 is incident on the G2 lens group. After being modulated by the positive power lens, negative power cemented lens and positive and negative power single lenses in the G2 lens group, the beam is expanded by 2.25 times. At the same time, the field curvature and distortion are corrected. The optimized parallel light is transmitted to the objective lens through the junction surface S3 between the relay group and the objective lens. The beam from S3 and the connecting surface S3 is incident on the objective lens. It passes through nine single lenses with preset focal length ratios in the objective lens to complete beam convergence and near-infrared chromatic aberration correction. After passing through the solution layer L21, coverslip L22, and solution layer L23 of the objective lens, it is focused on the sample area with a diameter of 7.5mm to 8.5mm, realizing large field of view imaging at a working distance of 7.5mm to 8.5mm. The ratio of the focal lengths of each lens within the objective lens to the total focal length f of the objective lens satisfies the following: -0.25 < <-0.24; 0.26 < <0.28; 0.19 < <0.20; 0.43 < <0.44; -1.2< <-1.1; 0.30 < <0.40; 0.50 < <0.60; 0.30 < <0.40; 0.70 < <0.80; S4. The fluorescence signal generated by the sample excited by near-infrared light is collected using the collection numerical aperture of the objective lens (0.9~1.1). The fluorescence signal is transmitted in reverse along the original optical path. After passing through the objective lens and the relay group, the fluorescence signal is separated from the excitation light by an external optical beam splitter between the focal plane S2 and G2 lens groups. The separated fluorescence signal is then transmitted to the photoelectric detection device to restore a high signal-to-noise ratio sample image.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. A microscope objective system and method with a large objective field of view and a long working distance, which for the first time achieves the combination of a large objective field of view (7.5mm~8.5mm in diameter), a long working distance (7.5mm~8.5mm), a high collection numerical aperture (0.9~1.1) and a numerical aperture of 0.5~0.6. It solves the technical contradiction of traditional objectives sacrificing resolution for long working distance and difficulty in achieving high collection efficiency with a large field of view, and meets the requirements for fine structural analysis at the level of single neurons and dendritic spines.

[0016] 2. A microscope objective system and method with a large objective field of view and a long working distance, which achieves precise aberration control through the coordinated design of the relay group and the objective lens, with the edge field curvature less than 10 μm, the absolute value of distortion less than 1.7362%, and the transverse chromatic aberration less than 0.705 μm; the maximum field of view RMS radius in the dot plot is smaller than the Airy disk radius, the MTF transfer function curve is close to the diffraction limit, and the imaging quality reaches the optical diffraction limit.

[0017] 3. A microscope objective system and method with a large field of view and long working distance. The working distance of about 8 mm can pass through the cranial window and cerebrospinal fluid to observe deep brain regions in mice. It provides sufficient space for the operation tools for optogenetic stimulation and extracellular electrophysiological recording, and is suitable for in vivo multimodal experiments. The large field of view greatly reduces the sample slice splicing operation, improves imaging throughput and efficiency, and facilitates long-term dynamic tracking of samples. The 920nm~940nm near-infrared band is optimized to improve the sensitivity and signal-to-noise ratio of in vivo functional imaging of deep brain regions.

[0018] 4. A microscope objective system and method with a large objective field of view and a long working distance. The planar design of the image side of lens L20 avoids the problem of air bubbles when using it in liquid immersion, reducing the difficulty of operation. The space reserved for external equipment in the relay group can be adapted to various optical modulation and beam splitting devices, supporting the subsequent processing and analysis of optical information. The beam expanding function can be matched with small-aperture optoelectronic devices such as resonant mirrors, improving the adaptability of the microscope objective system. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of a relay group; Figure 3 This is a schematic diagram of the objective lens; Figure 4 Schematic diagram of objective lens numerical aperture and collection numerical aperture; Figure 5 The system field curvature and distortion curves are shown. Figure 6 For the system's vertical axis color difference curve Figure 7 A point-to-point diagram of the system; Figure 8 This is the system MTF curve.

[0020] The components marked in the attached diagram are as follows: S1, aperture plane; S2, focal plane; S3, connecting plane; L1-L20, optical lenses; L21, first solution layer; L22, coverslip; L23, second solution layer; G1, G1 lens group; G2, G2 lens group; θ1, numerical aperture half angle; θ2, collecting numerical aperture half angle. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] like Figures 1-8 As shown, one of the objectives of this invention is to provide a microscope objective system with a large objective field of view and a long working distance, comprising a microscope objective system including twenty optical lenses arranged coaxially, two solution layers and a coverslip, with a relay group and objectives arranged sequentially from the object side to the image side; The relay group includes the G1 lens group, which consists of surface S1, lens L1, lens L2, lens L3, lens L4, lens L5, lens L6, and surface S2, arranged from the object side to the image side. The G2 lens group consists of surface S2, lens L7, lens L8, lens L9, lens L10, lens L11, and surface S3, arranged from the object side to the image side. Surface S2 is a common surface of the G1 lens group and the G2 lens group, and surface S3 is the connecting surface between the relay group and the objective lens.

[0023] The objective lenses, from the object side to the image side, are as follows: plane S3, lens L12, lens L13, lens L14, lens L15, lens L16, lens L17, lens L18, lens L19, lens L20, solution layer L21, coverslip L22, and solution layer L23. L1, L6, L11, L12, and L16 represent negative optical power; L2-L5, L7, L10, L13-L15, and L17-L20 represent positive optical power. L2 and L3, and L4 and L5 form positive bonding groups; L8 and L9 form negative bonding groups. L20 has a flat side to avoid liquid immersion bubbles and improves stability during use.

[0024] The focal lengths of the internal lenses and the total focal length f of the objective lens are configured in the following proportions to ensure near-infrared chromatic aberration correction and long working distance focusing:

[0025] The focal length of lens L12 and the focal length of the objective lens satisfy: -0.25 < <-0.24; The focal length of lens L13 and the focal length of the objective lens satisfy: 0.26 < <0.28; The focal length of lens L14 and the focal length of the objective lens satisfy: 0.19 < <0.20; The focal length of lens L15 and the focal length of the objective lens satisfy: 0.43 < <0.44; The focal length of lens L16 and the focal length of the objective lens satisfy: -1.2 < <-1.1; The focal length of lens L17 and the focal length of the objective lens satisfy: 0.30 < <0.40; The focal length of lens L18 and the focal length of the objective lens satisfy: 0.50 < <0.60; The focal length of lens L19 and the focal length of the objective lens satisfy: 0.30 < <0.40; The focal length of lens L20 and the focal length of the objective lens satisfy: 0.70 < <0.80; in, fThe focal length of the objective lens. The focal length of lens L12 The focal length of lens L13. This is the focal length of lens L14. This is the focal length of lens L15. This is the focal length of lens L16. This is the focal length of lens L17. This is the focal length of lens L18. This is the focal length of lens L19. This is the focal length of lens L20.

[0026] Solution layers L21 and L23 are working medium layers. The working distance of the objective lens is 7.5mm~8.5mm, which is the distance from the image side of lens L20 to the image side of lens L23.

[0027] The numerical aperture of the microscope objective system is 0.5~0.6, the collection numerical aperture is 0.9~1.1, and the final imaging surface diameter is 7.5mm~8.5mm. This final imaging surface is the surface on which the sample is placed during actual use, i.e., the object plane.

[0028] The effective focal length of the G1 lens group is 100mm, and the effective focal length of the G2 lens group is 225mm. The combination of G1 and G2 achieves a beam expansion of 2.25 times. The distance between the surface S2 and the object side of the lens L7 is 260mm. Within this distance range, external optical modulation elements and beam splitters can be placed.

[0029] Working principle: In the relay group beam expansion and aberration optimization stage, the external parallel incident light first arrives at the relay group surface S1 (aperture stop). After the aperture is adjusted by the aperture stop, it enters the G1 lens group. Through the synergistic effect of the negative power lens L1, two sets of positive power cemented lenses (L2+L3, L4+L5), and the negative power lens L6, the parallel light is converged to surface S2 (focal plane), completing the initial aberration correction (spherical aberration, coma). Subsequently, the beam enters the G2 lens group from surface S2. After secondary modulation by the positive power lens L7, the negative power cemented lens (L8+L9), the positive power lens L10, and the negative power lens L11, a 2.25x beam expansion is achieved to match the light transmission requirements of small-aperture optoelectronic devices (such as resonant mirrors, deflected ±11.2°) and large-aperture objectives. At the same time, field curvature and distortion are further corrected. Finally, the optimized parallel light is transmitted to the objective lens module through surface S3 (connecting surface). In addition, the 260mm reserved space on the side of surface S2 and L7 can be used to mount an external beam splitter to separate the excitation light and fluorescence, providing a basis for subsequent fluorescence signal collection.

[0030] In the long working distance immersion imaging stage of the objective lens, the beam optimized by the relay group enters the objective lens module from surface S3, and is precisely modulated by nine single lenses from L12 to L20. Each lens is matched according to the preset focal length ratio to achieve secondary convergence and chromatic aberration correction (especially the transverse chromatic aberration correction in the near-infrared band). The image side of lens L20 is designed as a plane, which fits seamlessly with the water-based solution layer L21 to avoid the generation of bubbles in immersion imaging and ensure lossless light transmission. After passing through the solution layer L21, the coverslip L22, and the solution layer L23, the beam reaches the final imaging surface (the actual object surface, i.e., the mouse brain sample). The 8.0 mm working distance provides sufficient physical space for the mouse cranial window and cerebrospinal fluid layer, and the beam covers a sample area with a diameter of 8.0 mm, realizing large field-of-view, stitch-free imaging.

[0031] In the efficient fluorescence collection and signal transmission stage, after the near-infrared excitation light irradiates the mouse brain sample, the fluorescence signal generated by the sample is transmitted in reverse along the original optical path. The objective lens, as the core of fluorescence collection, achieves a high collection numerical aperture of 1.0 by limiting the light transmission aperture of each lens, which greatly improves the collection efficiency of fluorescence photons. After the fluorescence signal is transmitted through the objective lens and the relay group to the beam splitter external to surface S2, it is separated from the excitation light and received by the subsequent photoelectric detection equipment, and finally restored into a sample image with a high signal-to-noise ratio.

[0032] The second objective of this invention is to provide a method for using a microscope objective lens with a large field of view and a long working distance, for use in any of the above-mentioned microscope objective lens systems with a large field of view and a long working distance, comprising the following steps: S1. Parallel incident light in the near-infrared band of 920nm~940nm is introduced into the relay group aperture S1 of the microscope objective system. After the aperture is adjusted, the light is incident on the G1 lens group. Through the synergistic effect of the negative optical power lens and the two positive optical power cemented lenses in the G1 lens group, the parallel light is focused to the focal plane S2 to complete the initial aberration correction. The beam at focal plane S2 is incident on the G2 lens group. After being modulated by the positive power lens, negative power cemented lens and positive and negative power single lenses in the G2 lens group, the beam is expanded by 2.25 times. At the same time, the field curvature and distortion are corrected. The optimized parallel light is transmitted to the objective lens through the junction surface S3 between the relay group and the objective lens. The beam from S3 and the connecting surface S3 is incident on the objective lens. It passes through nine single lenses with preset focal length ratios in the objective lens to complete beam convergence and near-infrared chromatic aberration correction. After passing through the solution layer L21, coverslip L22, and solution layer L23 of the objective lens, it is focused on the sample area with a diameter of 7.5mm to 8.5mm, realizing large field of view imaging at a working distance of 7.5mm to 8.5mm. The ratio of the focal lengths of each lens within the objective lens to the total focal length f of the objective lens satisfies the following: -0.25 < <-0.24; 0.26 < <0.28; 0.19 < <0.20; 0.43 < <0.44; -1.2< <-1.1; 0.30 < <0.40; 0.50 < <0.60; 0.30 < <0.40; 0.70 < <0.80; S4. The fluorescence signal generated by the sample excited by near-infrared light is collected using the collection numerical aperture of the objective lens (0.9~1.1). The fluorescence signal is transmitted in reverse along the original optical path. After passing through the objective lens and the relay group, the fluorescence signal is separated from the excitation light by an external optical beam splitter between the focal plane S2 and G2 lens groups. The separated fluorescence signal is then transmitted to the photoelectric detection device to restore a high signal-to-noise ratio sample image.

[0033] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A microscope objective system with a large objective field of view and a long working distance, characterized in that: The microscope objective system includes twenty optical lenses arranged coaxially, two solution layers and a coverslip, with relay groups and objectives arranged sequentially from the object side to the image side; The relay group includes the G1 lens group and the G2 lens group; The G1 lens group consists of, from the object side to the image side, plane S1, lens L1, lens L2, lens L3, lens L4, lens L5, lens L6, and plane S2. The G2 lens group consists of surface S2, lens L7, lens L8, lens L9, lens L10, lens L11, and surface S3, from the object side to the image side. The objective lenses, from the object side to the image side, are as follows: plane S3, lens L12, lens L13, lens L14, lens L15, lens L16, lens L17, lens L18, lens L19, lens L20, solution layer L21, coverslip L22, and solution layer L23. The surface S1 is an aperture stop; lens L1 is a negative power lens, with a concave object side and a convex image side; lenses L2 and L3 form the first group of positive power cemented lenses, with lens L2 having a concave object side and a concave image side, and lens L3 having a convex image side; lenses L4 and L5 form the second group of positive power cemented lenses, with lens L4 having a convex object side and a concave image side, and lens L5 having a concave image side; lens L6 is a negative power lens with a concave object side. The object side and image side are convex; object side S2 is the focal plane after parallel light passes through the G1 lens group; lens L7 is a positive power lens with a concave object side and a convex image side; lens L8 and lens L9 form a negative power cemented lens, with lens L8 having a convex object side and a convex image side, and lens L9 having a concave image side; lens L10 is a positive power lens with a convex object side and a concave image side; lens L11 is a negative power lens with a convex object side and a concave image side. Lens L12 is a negative power lens with a convex object side and a concave image side; lenses L13, L14, L15, L17, L18, L19, and L20 are all positive power lenses, and lens L16 is a negative power lens; lenses L13 and L14 have convex object sides and image sides, lenses L15, L17, L18, and L19 have convex object sides and concave image sides, lens L16 has concave object sides and image sides, and lens L20 has a convex object side and a flat image side; The numerical aperture of the microscope objective system is 0.5~0.6, the collection numerical aperture is 0.9~1.1, and the final imaging surface diameter is 7.5mm~8.5mm. The final imaging surface is the surface on which the sample is placed during actual use. The optical components with optical power in the microscope objective system are only the twenty optical lenses.

2. The microscope objective system with a large objective field of view and long working distance according to claim 1, characterized in that: Surface S2 is a common surface of lens group G1 and lens group G2, and surface S3 is the connecting surface between relay group and objective lens.

3. The microscope objective system with a large objective field of view and long working distance according to claim 1, characterized in that: The surface S3 is the common surface of the objective lens and the relay group, and the image side of L23 is the surface on which the sample is placed when the microscope objective lens system is actually used, i.e., the object side.

4. The microscope objective system with a large objective field of view and long working distance according to claim 1, characterized in that: The focal length of lens L12 and the focal length of the objective lens satisfy: -0.25 < <-0.24; The focal length of lens L13 and the focal length of the objective lens satisfy: 0.26 < <0.28; The focal length of lens L14 and the focal length of the objective lens satisfy: 0.19 < <0.20; The focal length of lens L15 and the focal length of the objective lens satisfy: 0.43 < <0.44; The focal length of lens L16 and the focal length of the objective lens satisfy: -1.2 < <-1.1; The focal length of lens L17 and the focal length of the objective lens satisfy: 0.30 < <0.40; The focal length of lens L18 and the focal length of the objective lens satisfy: 0.50 < <0.60; The focal length of lens L19 and the focal length of the objective lens satisfy: 0.30 < <0.40; The focal length of lens L20 and the focal length of the objective lens satisfy: 0.70 < <0.80; Where f is the focal length of the objective lens. The focal length of lens L12 The focal length of lens L13. This is the focal length of lens L14. This is the focal length of lens L15. This is the focal length of lens L16. This is the focal length of lens L17. This is the focal length of lens L18. This is the focal length of lens L19. This is the focal length of lens L20.

5. The microscope objective system with a large objective field of view and long working distance according to claim 1, characterized in that: The solution layers L21 and L23 are working medium layers. The working distance of the objective lens is 7.5mm to 8.5mm, which is the distance from the image side of lens L20 to the image side of lens L23.

6. The microscope objective system with a large objective field of view and long working distance according to claim 2, characterized in that: The effective focal length of the G1 lens group is 100mm, and the effective focal length of the G2 lens group is 225mm. The G1 lens group and the G2 lens group work together to achieve a beam expansion of 2.25 times. The distance between the surface S2 and the object side of the lens L7 is 260mm. Within this distance range, external optical modulation elements and beam splitters can be placed.

7. A method for using a microscope objective lens with a large objective field of view and a long working distance, for use in a microscope objective lens system with a large objective field of view and a long working distance as described in any one of claims 1-6, characterized in that: Includes the following steps: S1. Parallel incident light in the near-infrared band of 920nm~940nm is introduced into the relay group aperture S1 of the microscope objective system. After the aperture is adjusted, the light is incident on the G1 lens group. Through the synergistic effect of the negative optical power lens and the two positive optical power cemented lenses in the G1 lens group, the parallel light is focused to the focal plane S2 to complete the initial aberration correction. The beam at focal plane S2 is incident on the G2 lens group. After being modulated by the positive power lens, negative power cemented lens and positive and negative power single lenses in the G2 lens group, the beam is expanded by 2.25 times. At the same time, the field curvature and distortion are corrected. The optimized parallel light is transmitted to the objective lens through the junction surface S3 between the relay group and the objective lens. The beam from S3 and the connecting surface S3 is incident on the objective lens. It passes through nine single lenses with preset focal length ratios in the objective lens to complete beam convergence and near-infrared chromatic aberration correction. After passing through the solution layer L21, coverslip L22, and solution layer L23 of the objective lens, it is focused on the sample area with a diameter of 7.5mm to 8.5mm, realizing large field of view imaging at a working distance of 7.5mm to 8.5mm. The ratio of the focal lengths of each lens within the objective lens to the total focal length f of the objective lens satisfies the following: -0.25＜ ＜-0.24； 0.26＜ ＜0.28； 0.19＜ ＜0.20； 0.43＜ ＜0.44； -1.2＜ ＜-1.1； 0.30＜ ＜0.40； 0.50＜ ＜0.60； 0.30＜ ＜0.40； 0.70＜ ＜0.80； Where f is the focal length of the objective lens. The focal length of lens L12 The focal length of lens L13. This is the focal length of lens L14. This is the focal length of lens L15. This is the focal length of lens L16. This is the focal length of lens L17. This is the focal length of lens L18. This is the focal length of lens L19. This is the focal length of lens L20; S4. The fluorescence signal generated by the sample excited by near-infrared light is collected using the collection numerical aperture of the objective lens (0.9~1.1). The fluorescence signal is transmitted in reverse along the original optical path. After passing through the objective lens and the relay group, the fluorescence signal is separated from the excitation light by an external optical beam splitter between the focal plane S2 and G2 lens groups. The separated fluorescence signal is then transmitted to the photoelectric detection device to restore a high signal-to-noise ratio sample image.

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