A microscope objective

Abstract

The application provides a microscope objective, and belongs to the technical field of optical imaging. The microscope objective comprises a first lens group, a second lens group and a third lens group which are coaxially arranged in sequence from an image side to an object side. The focal length of the first lens group satisfies 5.5<|f1 / f|≤7.5. The focal length of the second lens group satisfies 13≤|f2 / f|≤16. The focal length of the third lens group satisfies 2≤|f3 / f|≤3.5. Wherein, f is the total focal length of the microscope objective, f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, and f3 is the focal length of the third lens group. The numerical aperture of the microscope objective is increased to 0.37, the distortion is reduced to 0.037%, and the working distance is 20mm. The long working distance and high resolution are realized, and the use requirement of precise measurement is met.

Description

Technical Field

[0001] This application belongs to the field of optical imaging technology, specifically relating to a microscope objective. Background Technology

[0002] With the continuous diversification of applications in microscopic detection, the industry has placed higher demands on the operability and detection efficiency of microscope objectives, focusing on two key performance aspects: long working distance and large imaging field of view. A long working distance allows for ample space between the objective and the observed sample, not only ensuring compatibility with other components of the detection system but also reducing focusing difficulty and the risk of sample damage. A large imaging field of view allows for the acquisition of richer observational information in a single pass, effectively increasing throughput and thus optimizing overall detection efficiency. Therefore, while ensuring image quality, further improving the working distance and imaging field of view of microscope objectives has become a key direction for optimizing their operability and improving detection efficiency, and is of great significance to the development of the field of microscopic detection.

[0003] Among related technologies, CN118131451A describes a 10x apochromatic microscope objective with a long working distance and large field of view. This design, using four lenses, achieves a 10x long working distance and large field of view visible light apochromatic plan objective with a working distance of 27mm and a numerical aperture of 0.27. However, this design still has significant shortcomings: the numerical aperture is only 0.27, and the distortion is as high as 0.39%. Therefore, it is difficult to simultaneously achieve both a long working distance and high resolution, and it cannot meet the requirements of precision measurement. Summary of the Invention

[0004] Therefore, the purpose of this application is to provide a microscope objective that at least solves the technical problem mentioned in the background art of the difficulty in simultaneously achieving both long working distance and high resolution, thus failing to meet the requirements of precision measurement.

[0005] To address the aforementioned problems, this application provides a microscope objective, comprising: A first lens group, a second lens group, and a third lens group are arranged coaxially from the image side to the object side. The focal length of the first lens group satisfies 5.5 < |f1 / f| ≤ 7.5; the focal length of the second lens group satisfies 13 ≤ |f2 / f| ≤ 16; and the focal length of the third lens group satisfies 2 ≤ |f3 / f| ≤ 3.5. Where: f is the total focal length of the microscope objective; f1 is the focal length of the first lens group; f2 is the focal length of the second lens group; and f3 is the focal length of the third lens group.

[0006] Optionally, the first lens group has a negative optical power and includes a first lens and a second lens. The first lens and the second lens are arranged sequentially along the same optical axis from the image side to the object side, and the object side of the first lens and the image side of the second lens are cemented together.

[0007] Optionally, the first lens is a biconvex lens with positive optical power and a focal length of 20mm to 30mm.

[0008] Optionally, the second lens is a biconcave lens with negative optical power and a focal length of -20mm to -10mm.

[0009] Optionally, the second lens group has positive optical power and includes a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens. The third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are arranged sequentially along the same optical axis from the image side to the object side. The object side of the third lens is cemented to the image side of the fourth lens, and the object side of the fourth lens is cemented to the image side of the fifth lens, so that the third lens, the fourth lens, and the fifth lens form a three-cemented lens group. The object side of the sixth lens is cemented to the image side of the seventh lens.

[0010] Optionally, the air gap between the object side of the second lens and the image side of the third lens is 18mm to 25mm.

[0011] Optionally, the air gap between the object side of the fifth lens and the image side of the sixth lens is 1mm to 3mm.

[0012] Optionally, the air gap between the object side of the seventh lens and the image side of the eighth lens is 0.05 mm to 0.2 mm.

[0013] Optionally, the third lens is a biconcave lens with negative optical power and a focal length of -12mm to -8mm.

[0014] Optionally, the fourth lens is a meniscus lens with positive optical power and a focal length of 25mm to 32mm.

[0015] Optionally, the fifth lens is a biconvex lens with positive optical power and a focal length of 14mm to 18mm.

[0016] Optionally, the sixth lens is a biconcave lens with negative optical power and a focal length of -18mm to -12mm.

[0017] Optionally, the seventh lens is a biconvex lens with positive optical power and a focal length of 26mm to 35mm.

[0018] Optionally, the eighth lens is a biconvex lens with positive optical power and a focal length of 50mm to 66mm.

[0019] Optionally, the third lens group has positive optical power and includes a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, and a thirteenth lens; the ninth lens, the tenth lens, the eleventh lens, the twelfth lens, and the thirteenth lens are arranged sequentially along the same optical axis from the image side to the object side; the object side of the twelfth lens is cemented to the image side of the thirteenth lens.

[0020] Optionally, the air gap between the object side of the ninth lens and the image side of the tenth lens is 0.5 mm to 2 mm.

[0021] Optionally, the air gap between the object side of the tenth lens and the image side of the eleventh lens is 0.05 mm to 0.2 mm.

[0022] Optionally, the air gap between the object side of the eleventh lens and the image side of the twelfth lens is 0.05 mm to 0.2 mm.

[0023] Optionally, the ninth lens is a meniscus lens with positive optical power and a focal length of 250mm to 270mm.

[0024] Optionally, the tenth lens is a meniscus lens with positive optical power and a focal length of 300mm to 450mm.

[0025] Optionally, the eleventh lens is a biconvex lens with positive optical power and a focal length of 40mm to 60mm.

[0026] Optionally, the twelfth lens is a biconvex lens with positive optical power and a focal length of 30mm to 42mm.

[0027] Optionally, the thirteenth lens is a meniscus lens with negative optical power and a focal length of -60mm to -45mm.

[0028] By employing the above technical solution, the present invention has at least the following beneficial effects: This application provides a microscope objective comprising a first lens group, a second lens group, and a third lens group arranged coaxially from the image side to the object side. The focal length of the first lens group satisfies 5.5 < |f1 / f| ≤ 7.5, the focal length of the second lens group satisfies 13 ≤ |f2 / f| ≤ 16, and the focal length of the third lens group satisfies 2 ≤ |f3 / f| ≤ 3.5. The numerical aperture is increased to 0.37, the distortion is reduced to 0.037%, and the working distance is 20 mm, achieving a balance between long working distance and high resolution, meeting the requirements for precision measurement. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the microscope objective structure according to an embodiment of this application.

[0030] The reference numerals in the attached figures are as follows: A. First lens group; A1. First lens; A2. Second lens; B, Second lens group; B1, Third lens; B2, Fourth lens; B3, Fifth lens; B4, Sixth lens; B5, Seventh lens; B6, Eighth lens; C. Third lens group; C1. Ninth lens; C2. Tenth lens; C3. Eleventh lens; C4. Twelfth lens; C5. Thirteenth lens. Detailed Implementation

[0031] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0033] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0035] See also Figure 1 As shown, according to an embodiment of this application, a microscope objective is provided, comprising: The first lens group A, the second lens group B, and the third lens group C are arranged coaxially from the image side to the object side. The focal length of the first lens group A satisfies 5.5 < |f1 / f| ≤ 7.5; the focal length of the second lens group B satisfies 13 ≤ |f2 / f| ≤ 16; and the focal length of the third lens group C satisfies 2 ≤ |f3 / f| ≤ 3.5. Where: f is the total focal length of the microscope objective; f1 is the focal length of the first lens group A; f2 is the focal length of the second lens group B; and f3 is the focal length of the third lens group C.

[0036] The first lens group A, the second lens group B, and the third lens group C are arranged coaxially from the image side to the object side. The numerical aperture is increased to 0.37, the distortion is reduced to 0.037%, and the working distance is 20mm. This achieves a balance between long working distance and high resolution, meeting the requirements of precision measurement.

[0037] The focal length of the first lens group A satisfies 5.5 < |f1 / f| ≤ 7.5; the focal length of the second lens group B satisfies 13 ≤ |f2 / f| ≤ 16; and the focal length of the third lens group C satisfies 2 ≤ |f3 / f| ≤ 3.5. The first lens group A causes the incident beam passing through it to diverge, diffusing the incident edge beam to a preset height while retaining a certain amount of negative spherical aberration. Simultaneously, its focal length is limited to the range of 5.5 < |f1 / f| ≤ 7.5 to control the beam divergence angle and avoid difficulties in correcting aberrations. The second lens group B is used to correct the chromatic aberration and second-order spectrum of the system, as well as the field curvature, astigmatism, and coma. Its focal length is limited to the range of 13≤|f2 / f|≤16 to ensure stable aberration correction. The third lens group C is responsible for the large-angle deflection of light and shares the optical power of the light beam. Its focal length is limited to the range of 2≤|f3 / f|≤3.5, which makes the optical path of the light beam longer, thus leaving a longer back working distance, while effectively correcting the residual spherical aberration and field curvature of the system.

[0038] This application describes an infinite conjugate imaging system with a reverse design. The incident polychromatic beam emitted from the object side passes sequentially through the third lens group C, the second lens group B, and the first lens group A, exiting as a parallel beam, which is then converged into an image through the microscope tube. The central optical path of the microscope objective and the tube lens is a parallel beam, and different filters and beam splitters can be added as needed to expand its applications.

[0039] In this application, the structure, function and positional relationship of the lens group and each lens are based on the actual direction of light propagation (from the object side to the parallel light emission side), that is, the third lens group C, the second lens group B and the first lens group A are arranged sequentially from the object side to the image side.

[0040] The first lens group A has a negative optical power and includes a first lens A1 and a second lens A2. The first lens A1 and the second lens A2 are arranged sequentially along the same optical axis from the image side to the object side. The object side of the first lens A1 and the image side of the second lens A2 are cemented together.

[0041] The incident beam diverges after passing through the first lens group A, causing the incident edge beam to diverge to a preset height, leaving a preset negative spherical aberration.

[0042] Both the preset height and the preset negative ball difference can be selected according to the actual working conditions.

[0043] The object side of the first lens A1 and the image side of the second lens A2 are cemented together to efficiently correct axial chromatic aberration and second-order spectral aberration, while retaining a preset negative spherical aberration, which facilitates the overall aberration balance of the system. At the same time, it reduces air surface reflection and improves light transmittance and imaging contrast.

[0044] The first lens A1 is a biconvex lens with positive optical power and a focal length of 20mm to 30mm.

[0045] Specifically, the first lens A1 is a biconvex lens with positive optical power, meaning that both the image-side and object-side surfaces are convex. The first lens A1 is used to perform preliminary focusing and shaping of the incident beam, providing the required positive optical power and generating positive spherical aberration.

[0046] The second lens A2 is a biconcave lens with negative optical power and a focal length of -20mm to -10mm.

[0047] Specifically, the second lens A2 is a biconcave lens with negative optical power, meaning that both the image-side and object-side surfaces are concave. The second lens A2 is used to make the first lens group A exhibit a diverging effect, diverging the edge beams to a suitable height, while simultaneously generating negative spherical aberration, so that the first lens group A retains a preset negative spherical aberration, so as to cooperate with subsequent lens groups to achieve overall aberration balance of the system.

[0048] More specifically, the object-side convex surface of the first lens A1 and the image-side concave surface of the second lens A2 have the same radius of curvature, which allows the object-side surface of the first lens A1 and the image-side surface of the second lens A2 to fit tightly and without gaps, thereby achieving reliable bonding, avoiding assembly stress and additional aberrations, and improving the imaging quality and stability of the system; at the same time, while realizing the divergence of the incident edge beam and the residual negative spherical aberration, it effectively corrects chromatic aberration.

[0049] The second lens group B has positive optical power and includes a third lens B1, a fourth lens B2, a fifth lens B3, a sixth lens B4, a seventh lens B5, and an eighth lens B6. These lenses are arranged sequentially along the same optical axis from the image side to the object side. The object side of the third lens B1 is cemented to the image side of the fourth lens B2, and the object side of the fourth lens B2 is cemented to the image side of the fifth lens B3, so that the third lens B1, the fourth lens B2, and the fifth lens B3 form a three-cemented lens group. The object side of the sixth lens B4 is cemented to the image side of the seventh lens B5.

[0050] The second lens group B is used to correct chromatic aberration and secondary spectrum, as well as field curvature, astigmatism, and coma of the system.

[0051] Specifically, the object-side surface of the third lens B1 is cemented with the image-side surface of the fourth lens B2, and the object-side surface of the fourth lens B2 is cemented with the image-side surface of the fifth lens B3, so that the third lens B1, the fourth lens B2, and the fifth lens B3 form a cemented triplet lens group. This cemented triplet lens group is used to achieve high-intensity correction of chromatic aberration, second-order spectral density, and spherical aberration. At the same time, the object-side surface of the sixth lens B4 is cemented with the image-side surface of the seventh lens B5 to form a cemented doublet lens group, which further eliminates residual chromatic aberration, astigmatism, and field curvature, and improves image quality. Finally, the independent eighth lens B6 achieves final convergence imaging and fine-tunes the image plane. Meanwhile, the segmented cementing structure reduces air interfaces, reduces stray light, and improves structural stability and assembly accuracy.

[0052] Among them, the third lens B1 is a biconcave lens with negative optical power and a focal length of -12mm to -8mm.

[0053] Specifically, the third lens B1 is a biconcave lens with negative optical power, meaning that both the image-side and object-side surfaces of the third lens B1 are concave. The third lens B1 is used to provide negative optical power and generate negative spherical aberration, controlling the beam divergence power.

[0054] Among them, the fourth lens B2 is a meniscus lens with positive optical power and a focal length of 25mm to 32mm.

[0055] Specifically, the fourth lens B2 is a meniscus lens with positive optical power, meaning that the image-side of the fourth lens B2 is convex, while the object-side is concave. The fourth lens B2 serves as a transition lens, used to smooth beam deflection and finely correct field curvature.

[0056] Among them, the fifth lens B3 is a biconvex lens with positive optical power and a focal length of 14mm to 18mm.

[0057] Specifically, the fifth lens B3 is a biconvex lens with positive optical power, meaning that both the image-side and object-side surfaces of the fifth lens B3 are convex. The fifth lens B3 provides positive optical power and, together with the third lens B1 and the fourth lens B2, forms a cemented triplet lens group, strongly correcting chromatic aberration and second-order spectral density.

[0058] More specifically, the object-side concave surface of the third lens B1 and the image-side convex surface of the fourth lens B2 have the same radius of curvature; the object-side concave surface of the fourth lens B2 and the image-side convex surface of the fifth lens B3 have the same radius of curvature; this allows the object-side surface of the third lens B1 and the image-side surface of the fourth lens B2, as well as the object-side surface of the fourth lens B2 and the image-side surface of the fifth lens B3, to fit tightly and without gaps, thereby achieving reliable bonding, avoiding assembly stress and additional aberrations, and improving the imaging quality and stability of the system.

[0059] Among them, the sixth lens B4 is a biconcave lens with negative optical power and a focal length of -18mm to -12mm.

[0060] Specifically, the sixth lens B4 is a biconcave lens with negative optical power, meaning that both the image-side and object-side surfaces of the sixth lens B4 are concave. The sixth lens B4 is used in conjunction with the seventh lens B5 to eliminate residual chromatic aberration and balance higher-order spherical aberrations.

[0061] Among them, the seventh lens B5 is a biconvex lens with positive optical power and a focal length of 26mm to 35mm.

[0062] Specifically, the seventh lens B5 is a biconvex lens with positive optical power, meaning that both the image-side and object-side surfaces of the seventh lens B5 are convex. The seventh lens B5 works in conjunction with the sixth lens B4 to correct coma and astigmatism, improving the imaging quality at the edges of the field of view.

[0063] More specifically, the object-side concave surface of the sixth lens B4 and the image-side convex surface of the seventh lens B5 have the same radius of curvature, which allows the object-side surface of the sixth lens B4 and the image-side surface of the seventh lens B5 to fit tightly and without gaps, thereby achieving reliable bonding, avoiding assembly stress and additional aberrations, and improving the imaging quality and stability of the system.

[0064] Among them, the eighth lens B6 is a biconvex lens with positive optical power and a focal length of 50mm to 66mm.

[0065] Specifically, the eighth lens B6 is a biconvex lens with positive optical power, meaning that both the image-side and object-side surfaces of the eighth lens B6 are convex. The eighth lens B6 is located at the object end of the second lens group B to achieve final beam convergence and imaging, and uses the air gap between it and the seventh lens B5 to fine-tune the flatness of the image surface, ensuring high-definition imaging across the entire field of view.

[0066] The air gap between the object-side surface of the second lens A2 and the image-side surface of the third lens B1 is 18mm to 25mm. This air gap serves to achieve a smooth transition and matching of aberrations between the first lens group A and the second lens group B, absorb the residual negative spherical aberration of the first lens group A, adjust the beam incident angle, and reduce the aberration correction pressure on the second lens group B. Furthermore, it facilitates independent assembly and tolerance compensation of the first lens group A and the second lens group B, ensuring a compact system structure and imaging stability.

[0067] The air gap between the object-side surface of the fifth lens B3 and the image-side surface of the sixth lens B4 is 1mm to 3mm. This air gap between the object-side surface of the fifth lens B3 and the sixth lens B4 is used to adjust the aberration matching relationship between the cemented triplet lens group and the cemented doublet lens group, fine-tune spherical aberration, astigmatism, and field curvature, so that the cemented triplet lens group and the cemented doublet lens group achieve good aberration complementarity, and simultaneously adjust the beam incident angle to reduce higher-order aberrations.

[0068] The air gap between the object-side surface of the seventh lens B5 and the image-side surface of the eighth lens B6 is 0.05mm to 0.2mm. This air gap is used to finally correct the system field curvature, fine-tune residual coma and astigmatism, ensure a flat image plane and clear imaging across the entire field of view, and facilitate assembly tolerance allocation, thereby improving system stability.

[0069] The third lens group C has positive optical power and includes a ninth lens C1, a tenth lens C2, an eleventh lens C3, a twelfth lens C4, and a thirteenth lens C5. The ninth lens C1, the tenth lens C2, the eleventh lens C3, the twelfth lens C4, and the thirteenth lens C5 are arranged sequentially along the same optical axis from the image side to the object side. The object side of the twelfth lens C4 is cemented to the image side of the thirteenth lens C5.

[0070] The third lens group C is used to handle the large-angle deflection of light, share the optical power of the light beam, make the optical path of the light focus longer, leave a longer back working distance, and correct the residual spherical aberration and field curvature of the system.

[0071] Among them, the object side of the twelfth lens C4 and the image side of the thirteenth lens C5 are cemented together to form a cemented doublet lens. The two work together as a whole to improve the overall structure and assembly coaxiality, avoid additional aberrations caused by relative eccentricity, and improve the imaging quality and structural stability of the system.

[0072] Among them, the ninth lens C1 is a meniscus lens with positive optical power and a focal length of 250mm to 270mm. The tenth lens C2 is a meniscus lens with positive optical power and a focal length of 300mm to 450mm.

[0073] Specifically, the ninth lens C1 is a meniscus lens with positive optical power, meaning that the image-side surface of the ninth lens C1 is concave and the object-side surface is convex; the tenth lens C2 is a meniscus lens with positive optical power, meaning that the image-side surface of the ninth lens C1 is concave and the object-side surface is convex; both the ninth lens C1 and the tenth lens C2 are meniscus lenses with positive optical power, used to deflect and smooth the beam at large angles, effectively correct field curvature and astigmatism, and, in conjunction with extending the focusing optical path, provide support for achieving a long back working distance.

[0074] Among them, the eleventh lens C3 is a biconvex lens with positive optical power and a focal length of 40mm to 60mm.

[0075] Specifically, both the image-side and object-side surfaces of the eleventh lens C3 are convex. The eleventh lens C3 is a biconvex positive power lens, bearing the main positive power, achieving large-angle beam convergence, and balancing residual spherical aberration.

[0076] Among them, the twelfth lens C4 is a biconvex lens with positive optical power and a focal length of 30mm to 42mm. The thirteenth lens C5 is a meniscus lens with negative optical power and a focal length of -60mm to -45mm.

[0077] Specifically, the twelfth lens C4 is a biconvex lens with positive optical power, meaning both its image-side and object-side surfaces are convex; the thirteenth lens C5 is a meniscus lens with negative optical power, meaning its image-side surface is concave and its object-side surface is convex. The twelfth lens C4 provides the positive optical power required for beam combining, while the thirteenth lens C5 provides the negative optical power to compensate for residual spherical aberration and optimize field curvature. Together, they synergistically correct chromatic aberration, second-order spectral aberration, and residual aberrations.

[0078] The air gap between the object side of the ninth lens C1 and the image side of the tenth lens C2 is 0.5mm to 2mm. The air gap between the ninth lens C1 and the tenth lens C2 is used to achieve smooth beam transition, adjust field curvature and astigmatism, and reasonably allocate optical power.

[0079] The air gap between the object side of the tenth lens C2 and the image side of the eleventh lens C3 is 0.05mm to 0.2mm. The air gap between the tenth lens C2 and the eleventh lens C3 is used to adjust the incident angle of the beam, extend the focusing optical path to achieve a long back working distance, and fine-tune spherical aberration and field curvature.

[0080] The air gap between the object side of the eleventh lens C3 and the image side of the twelfth lens C4 is 0.05mm to 0.2mm. The air gap between the tenth lens C2 and the eleventh lens C3 is used to achieve aberration matching between the eleventh lens C3 and the cemented doublet lens group composed of the twelfth lens C4 and the thirteenth lens C5, suppress higher-order aberrations, and facilitate assembly and tolerance compensation.

[0081] Among them, the air gap between the object side and the object side of the thirteenth lens C5 is 20mm, that is, the working distance is 20mm.

[0082] Example 1 In this embodiment, the optical parameters shown in Table 1 are used for simulation.

[0083] Table 1 shows the specific optical parameters of the microscope objectives.

[0084] In this embodiment, the working distance WD is 20mm, the numerical aperture NA is 0.37, the MTF value of the spatial frequency of 750lp / mm is 0.3 within the full working field of view of the visible light range (d, F, c light), and the effective focal length f is 11mm. When used with a tube lens with a focal length of 110mm, the magnification is 10 times.

[0085] In this embodiment, the maximum focal shift between different spectral bands is less than 4 μm, fully meeting the apochromatic design conditions and effectively ensuring the consistency of multi-spectral imaging. The field curvature in this embodiment across the entire field of view is less than 2.3 μm, which is less than the system's depth of focus, indicating that the system meets the flat-field design conditions and effectively avoids blurring at the edges of the field of view. The maximum distortion in this embodiment is only 0.037%, indicating that system distortion has been effectively corrected, resulting in minimal imaging distortion and ensuring geometric accuracy of the image. The RMS wavefront aberration in this embodiment across the entire field of view is less than the diffraction limit, further demonstrating the system's excellent resolution, clear imaging, and superior imaging quality, meeting the requirements for high-precision imaging.

[0086] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0087] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A microscope objective, characterized in that, include: A first lens group (A), a second lens group (B), and a third lens group (C) are arranged coaxially from the image side to the object side. The focal length of the first lens group (A) satisfies 5.5 < |f1 / f| ≤ 7.5; the focal length of the second lens group (B) satisfies 13 ≤ |f2 / f| ≤ 16; and the focal length of the third lens group (C) satisfies 2 ≤ |f3 / f| ≤ 3.

5. Where: f is the total focal length of the microscope objective; f1 is the focal length of the first lens group (A); f2 is the focal length of the second lens group (B); and f3 is the focal length of the third lens group (C). The first lens group (A) has negative optical power and includes a first lens (A1) and a second lens (A2). The first lens (A1) and the second lens (A2) are arranged sequentially along the same optical axis from the image side to the object side. The object side of the first lens (A1) and the image side of the second lens (A2) are cemented together. The second lens group (B) has positive optical power and includes a third lens (B1), a fourth lens (B2), a fifth lens (B3), a sixth lens (B4), a seventh lens (B5), and an eighth lens (B6). These lenses are arranged sequentially along the same optical axis from the image side to the object side. The object side of the third lens (B1) is cemented to the image side of the fourth lens (B2), and the object side of the fourth lens (B2) is cemented to the image side of the fifth lens (B3), so that the third lens (B1), the fourth lens (B2), and the fifth lens (B3) form a three-cemented lens group. The object side of the sixth lens (B4) is cemented to the image side of the seventh lens (B5). The third lens group (C) has positive optical power and includes a ninth lens (C1), a tenth lens (C2), an eleventh lens (C3), a twelfth lens (C4), and a thirteenth lens (C5). The ninth lens (C1), the tenth lens (C2), the eleventh lens (C3), the twelfth lens (C4), and the thirteenth lens (C5) are arranged sequentially along the same optical axis from the image side to the object side. The object side of the twelfth lens (C4) is cemented to the image side of the thirteenth lens (C5).

2. A microscope objective according to claim 1, characterized in that, The first lens (A1) is a biconvex lens with positive optical power and a focal length of 20mm to 30mm; the second lens (A2) is a biconcave lens with negative optical power and a focal length of -20mm to -10mm.

3. A microscope objective according to claim 1, characterized in that, The air gap between the object side of the second lens (A2) and the image side of the third lens (B1) is 18mm to 25mm.

4. A microscope objective according to claim 1, characterized in that, The air gap between the object side of the fifth lens (B3) and the image side of the sixth lens (B4) is 1mm to 3mm; the air gap between the object side of the seventh lens (B5) and the image side of the eighth lens (B6) is 0.05mm to 0.2mm.

5. A microscope objective according to claim 1, characterized in that, The third lens (B1) is a biconcave lens with negative optical power and a focal length of -12mm to -8mm; the fourth lens (B2) is a meniscus lens with positive optical power and a focal length of 25mm to 32mm; the fifth lens (B3) is a biconvex lens with positive optical power and a focal length of 14mm to 18mm; the sixth lens (B4) is a biconcave lens with negative optical power and a focal length of -18mm to -12mm; the seventh lens (B5) is a biconvex lens with positive optical power and a focal length of 26mm to 35mm; and the eighth lens (B6) is a biconvex lens with positive optical power and a focal length of 50mm to 66mm.

6. A microscope objective according to claim 1, characterized in that, The air gap between the object side of the ninth lens (C1) and the image side of the tenth lens (C2) is 0.5 mm to 2 mm; the air gap between the object side of the tenth lens (C2) and the image side of the eleventh lens (C3) is 0.05 mm to 0.2 mm; and the air gap between the object side of the eleventh lens (C3) and the image side of the twelfth lens (C4) is 0.05 mm to 0.2 mm.

7. A microscope objective according to claim 1, characterized in that, The ninth lens (C1) is a meniscus lens with positive optical power and a focal length of 250mm to 270mm; the tenth lens (C2) is a meniscus lens with positive optical power and a focal length of 300mm to 450mm; the eleventh lens (C3) is a biconvex lens with positive optical power and a focal length of 40mm to 60mm; the twelfth lens (C4) is a biconvex lens with positive optical power and a focal length of 30mm to 42mm; and the thirteenth lens (C5) is a meniscus lens with negative optical power and a focal length of -60mm to -45mm.

Images