Microobjective

Abstract

The focal length of the microscope objective is f, the total optical length of the microscope objective is TTL, the image height of the microscope objective is IH, the combined focal length of a first lens and a second lens is f11, the focal length of a third lens is f3, the combined focal length of a fourteenth lens, a fifteenth lens and a sixteenth lens is f141516, the combined focal length of a seventeenth lens and an eighteenth lens is f1718, the thickness of the seventeenth lens on the axis is d33, the thickness of the eighteenth lens on the axis is d35, and the thickness of the fourth lens on the axis is d25. The following relational expressions are satisfied:-3.10 < = f11 / f3 < =-1.80; f141516 / f is more than or equal to 3.40 and less than or equal to 7.00; f1718 / (d33 + d35) is greater than or equal to 4.00 and less than or equal to 120.00; and 0.08 < = IH * f / TTL < = 0.09. The microscope objective lens is compact in structure, has excellent optical performance, and meets the design requirements of low distortion, 20-time magnification and long working distance.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of optical technology, and in particular to a microscope objective lens suitable for devices such as microscopes. Background Art

[0002] In recent years, the demand for microscope lenses has been increasing. However, due to the constraints of their optical structure, general microscope lenses will experience distortion within their microscopic range. On the other hand, since microscope lenses are composed of multiple lenses, their length will inevitably be affected. The long structure of the microscope lens will also shorten its working distance, and the magnification ratio will also be affected by the working distance, which is not conducive to operator use.

[0003] With the development of technology and the increasing diversified needs of users, scientific research has continuously increased the requirements for the observation quality of microscope lenses. There is an urgent need for microscope lenses with excellent optical characteristics, low distortion, high magnification, and long working distance. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a microscope objective lens with a large numerical aperture, a compact lens structure and good optical performance.

[0005] In order to solve the above technical problems, the present invention provides a microscope objective lens, which is composed of a first lens, a second lens, a third lens with negative refractive power, a fourth lens, a fifth lens, a sixth lens, a seventh lens with positive refractive power, an eighth lens, a ninth lens, a tenth lens with positive refractive power, an eleventh lens, a twelfth lens, a thirteenth lens with positive refractive power, a fourteenth lens, a fifteenth lens, a sixteenth lens, a seventeenth lens, and an eighteenth lens, which are arranged in sequence from the exit side to the object side; the focal length of the microscope objective lens is f, the combined focal length of the first lens and the second lens is f1-2, the focal length of the third lens is f3, the focal lengths of the fourteenth lens, the fifteenth lens, the sixteenth lens, the seventeenth lens, and the eighteenth lens are The combined focal length of the fifteenth lens and the sixteenth lens is f14_15_16, the combined focal length of the seventeenth lens and the eighteenth lens is f17_18, the on-axis thickness of the seventeenth lens is d33, the on-axis thickness of the eighteenth lens is d35, the on-axis distance from the object plane of the microscope objective lens to the exit surface of the first lens is TTL, the image height of the microscope objective lens is IH, and the following relationship is satisfied: -3.10≤f1_2 / f3≤-1.80; 3.40≤f14_15_16 / f≤7.00; 4.00≤f17_18 / (d33+d35)≤120.00; 0.08≤IH*f / TTL≤0.09.

[0006] Optionally, the curvature radius of the exit side surface of the tenth lens is R19, the curvature radius of the object side surface of the tenth lens is R20, and the following relationship is satisfied: -1.60≤R19 / R20≤-2.50.

[0007] Optionally, the on-axis distance from the object plane of the microscope objective lens to the object side surface of the eighteenth lens is WD, the numerical aperture NA of the microscope objective lens satisfies the following relationship: WD*NA≥1.10.

[0008] Optionally, the exit side surface of the first lens is convex at the paraxial position, and the object side surface of the first lens is convex at the paraxial position; the curvature radius of the exit side surface of the first lens is R1, the curvature radius of the object side surface of the first lens is R2, the axial thickness of the first lens is d1, and the following relationship is satisfied: -1.39≤(R1+R2) / (R1-R2)≤-0.24; 0.03≤d1 / TTL≤0.10.

[0009] Optionally, the exit side surface of the second lens is concave at the paraxial position, and the object side surface of the second lens is concave at the paraxial position; the curvature radius of the exit side surface of the second lens is R3, the curvature radius of the object side surface of the second lens is R4, the axial thickness of the second lens is d3, and the following relationship is satisfied: 0.15≤(R3+R4) / (R3-R4)≤1.13; 0.01≤d3 / TTL≤0.06.

[0010] Optionally, the object-side surface of the first lens and the exit-side surface of the second lens are glued to form a combined lens with positive refractive power, and the following relationship is satisfied: 1.93≤f1_2 / f≤8.42.

[0011] Optionally, the object side surface of the third lens is concave at the paraxial position; the radius of curvature of the exit side surface of the third lens is R5, the radius of curvature of the object side surface is R6, the axial thickness of the third lens is d5, and the following relationship is satisfied: 0.15≤(R5+R6) / (R5-R6)≤1.57; 0.01≤d5 / TTL≤0.03; -4.19≤f3 / f≤-1.24.

[0012] Optionally, the exit side surface of the fourth lens is concave at the paraxial position; the curvature radius of the exit side surface of the fourth lens is R7, the curvature radius of the object side surface of the fourth lens is R8, the axial thickness of the fourth lens is d7, and the following relationship is satisfied: -2.94≤(R7+R8) / (R7-R8)≤-0.12; 0.01≤d7 / TTL≤0.06.

[0013] Optionally, the object side surface of the fifth lens is convex at the paraxial position; the curvature radius of the exit side surface of the fifth lens is R9, the curvature radius of the object side surface of the fifth lens is R10, the axial thickness of the fifth lens is d9, and the following relationship is satisfied: 0.11≤(R9+R10) / (R9-R10)≤2.20; 0.04≤d9 / TTL≤0.15.

[0014] Optionally, the exit side surface of the sixth lens is concave at the paraxial position, and the object side surface of the sixth lens is convex at the paraxial position; the radius of curvature of the exit side surface of the sixth lens is R11, the radius of curvature of the object side surface of the sixth lens is R12, the axial thickness of the sixth lens is d11, and the following relationship is satisfied: -10.75≤(R11+R12) / (R11-R12)≤-2.17; 0.01≤d11 / TTL≤0.03.

[0015] Optionally, the object-side surface of the fourth lens is glued to the exit-side surface of the fifth lens, and the object-side surface of the fifth lens is glued to the exit-side surface of the sixth lens to form a combined lens with negative refractive power. The combined focal length of the fourth lens, the fifth lens, and the sixth lens is f4_5_6, and satisfies the following relationship: -7.70≤f4_5_6 / f≤-1.41.

[0016] Optionally, the object side surface of the seventh lens is convex; the curvature radius of the exit side surface of the seventh lens is R13, the curvature radius of the object side surface of the seventh lens is R14, the axial thickness of the seventh lens is d13, the focal length of the seventh lens is f7, and the following relationship is satisfied: 0.41≤(R13+R14) / (R13-R14)≤2.60; 0.02≤d13 / TTL≤0.09; 2.16≤f7 / f≤7.34.

[0017] Optionally, the exit side surface of the eighth lens is convex at the paraxial position, and the object side surface of the eighth lens is convex at the paraxial position; the radius of curvature of the exit side surface of the eighth lens is R15, the radius of curvature of the object side surface of the eighth lens is R16, the on-axis thickness of the eighth lens is d15, and the following relationship is satisfied: 0.19≤(R15+R16) / (R15-R16)≤1.15; 0.05≤d15 / TTL≤0.16.

[0018] Optionally, the exit side surface of the ninth lens is concave at the paraxial position, and the object side surface of the ninth lens is convex at the paraxial position; the radius of curvature of the exit side surface of the ninth lens is R17, the radius of curvature of the object side surface of the ninth lens is R18, the on-axis thickness of the ninth lens is d17, and the following relationship is satisfied: -5.69≤(R17+R18) / (R17-R18)≤-0.82; 0.01≤d17 / TTL≤0.04.

[0019] Optionally, the object-side surface of the eighth lens is glued to the exit-side surface of the ninth lens to form a combined lens with positive refractive power, and the combined focal length of the eighth lens and the ninth lens is f8_9, and satisfies the following relationship: 4.08≤f8_9 / f≤84.27.

[0020] Optionally, the exit side surface of the tenth lens is convex at the paraxial position, and the object side surface of the tenth lens is convex at the paraxial position; the curvature radius of the exit side surface of the tenth lens is R19, the curvature radius of the object side surface of the tenth lens is R20, the on-axis thickness of the tenth lens is d19, the focal length of the tenth lens is f10, and the following relationship is satisfied: -1.10≤(R19+R20) / (R19-R20)≤0.31; 0.03≤d19 / TTL≤0.11; 2.38≤f10 / f≤12.26.

[0021] Optionally, the exit side surface of the eleventh lens is convex at the paraxial position, and the object side surface of the eleventh lens is convex at the paraxial position; the curvature radius of the exit side surface of the eleventh lens is R21, the curvature radius of the object side surface of the eleventh lens is R21, the axial thickness of the eleventh lens is d21, and the following relationship is satisfied: 0.02≤(R21+R22) / (R21-R22)≤1.02; 0.03≤d21 / TTL≤0.13.

[0022] Optionally, the exit side surface of the twelfth lens is concave at the near axis; the curvature radius of the exit side surface of the twelfth lens is R23, the curvature radius of the object side surface of the twelfth lens is R24, the axial thickness of the twelfth lens is d23, and the following relationship is satisfied: -2.18≤(R23+R24) / (R23-R24)≤-0.29; 0.01≤d23 / TTL≤0.04.

[0023] Optionally, the object-side surface of the eleventh lens is glued to the exit-side surface of the twelfth lens to form a combined lens with negative refractive power, and the combined focal length of the eleventh lens and the twelfth lens is f11_12, and satisfies the following relationship: -879.88≤f11_12 / f≤-5.21.

[0024] Optionally, the exit side surface of the thirteenth lens is convex at the paraxial position; the curvature radius of the exit side surface of the thirteenth lens is R25, the curvature radius of the object side surface of the thirteenth lens is R26, the on-axis thickness of the thirteenth lens is d25, the focal length of the thirteenth lens is f13, and the following relationship is satisfied: -3.04≤(R25+R26) / (R25-R26)≤-0.53; 0.03≤d25 / TTL≤0.10; 1.68≤f13 / f≤7.42.

[0025] Optionally, the exit side surface of the fourteenth lens is convex at the paraxial position, and the object side surface of the fourteenth lens is convex at the paraxial position; the curvature radius of the exit side surface of the fourteenth lens is R27, the curvature radius of the object side surface of the fourteenth lens is R28, the on-axis thickness of the fourteenth lens is d27, and the following relationship is satisfied: -1.06≤(R27+R28) / (R27-R28)≤-0.27; 0.04≤d27 / TTL≤0.13.

[0026] Optionally, the exit side surface of the fifteenth lens is concave at the paraxial position, and the object side surface of the fifteenth lens is concave at the paraxial position; the curvature radius of the exit side surface of the fifteenth lens is R29, the curvature radius of the object side surface of the fifteenth lens is R30, the axial thickness of the fifteenth lens is d29, and the following relationship is satisfied: -0.05≤(R29+R30) / (R29-R30)≤0.98; 0.01≤d29 / TTL≤0.03.

[0027] Optionally, the exit side surface of the sixteenth lens is convex at the paraxial position, and the object side surface of the sixteenth lens is convex at the paraxial position; the curvature radius of the exit side surface of the sixteenth lens is R31, the curvature radius of the object side surface of the sixteenth lens is R32, the axial thickness of the sixteenth lens is d31, and the following relationship is satisfied: -1.45≤(R31+R32) / (R31-R32)≤-0.29; 0.02≤d31 / TTL≤0.09.

[0028] Optionally, the object-side surface of the fourteenth lens is glued to the exit-side surface of the fifteenth lens, and the object-side surface of the fifteenth lens is glued to the exit-side surface of the sixteenth lens to form a combined lens with positive refractive power.

[0029] Optionally, the exit side surface of the seventeenth lens is convex at the paraxial position, and the object side surface of the seventeenth lens is convex at the paraxial position; the curvature radius of the exit side surface of the seventeenth lens is R33, the curvature radius of the object side surface of the seventeenth lens is R34, the axial thickness of the seventeenth lens is d33, and the following relationship is satisfied: -1.08≤(R33+R34) / (R33-R34)≤-0.17; 0.02≤d33 / TTL≤0.08.

[0030] Optionally, the exit side surface of the eighteenth lens is concave at the paraxial position, and the object side surface of the eighteenth lens is concave at the paraxial position; the curvature radius of the exit side surface of the eighteenth lens is R35, the curvature radius of the object side surface of the eighteenth lens is R36, the on-axis thickness of the eighteenth lens is d35, and the following relationship is satisfied: 0.25≤(R35+R36) / (R35-R36)≤0.93; 0.01≤d35 / TTL≤0.04.

[0031] Optionally, the object-side surface of the seventeenth lens and the exit-side surface of the eighteenth lens are glued to form a combined lens with positive refractive power, and the following relationship is satisfied: 1.30≤f17_18 / f≤81.29.

[0032] The beneficial effects of the present invention are as follows: through the configuration of the above-mentioned lenses, the trend of light between the lenses can be controlled, which helps to ensure a smooth transition of the outgoing light, making the lens structure compact, and controlling the total length of the lens while ensuring that the imaging range reaches the expected state, so that the microscope objective has a large numerical aperture, ensuring that the light has sufficient convergence ability, and has excellent optical performance, meeting the design requirements of low distortion, 20x magnification, and long working distance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0034] Figure 1 1 is a schematic structural diagram of a microscope objective lens according to a first embodiment of the present invention;

[0035] Figure 2 yes Figure 1 Schematic diagram of field curvature and distortion of the microscope objective lens shown;

[0036] Figure 3 yes Figure 1 Schematic diagram of chromatic aberration of magnification of the microscope objective lens shown;

[0037] Figure 4 yes Figure 1 Schematic diagram of the axial aberration of the microscope objective shown;

[0038] Figure 5 2 is a schematic structural diagram of a microscope objective lens according to a second embodiment of the present invention;

[0039] Figure 6 yes Figure 5 Schematic diagram of field curvature and distortion of the microscope objective lens shown;

[0040] Figure 7 yes Figure 5 Schematic diagram of chromatic aberration of magnification of the microscope objective lens shown;

[0041] Figure 8 yes Figure 5 Schematic diagram of the axial aberration of the microscope objective shown;

[0042] Figure 9 2 is a schematic structural diagram of a microscope objective lens according to a third embodiment of the present invention;

[0043] Figure 10 yes Figure 9 Schematic diagram of field curvature and distortion of the microscope objective lens shown;

[0044] Figure 11 yes Figure 9 Schematic diagram of chromatic aberration of magnification of the microscope objective lens shown;

[0045] Figure 12 yes Figure 9 Schematic diagram of the axial aberration of the microscope objective shown;

[0046] Figure 13 2 is a schematic structural diagram of a microscope objective lens according to a fourth embodiment of the present invention;

[0047] Figure 14 yes Figure 13 Schematic diagram of field curvature and distortion of the microscope objective lens shown;

[0048] Figure 15 yes Figure 13 Schematic diagram of chromatic aberration of magnification of the microscope objective lens shown;

[0049] Figure 16 yes Figure 13 Schematic diagram of the axial aberration of the microscope objective shown. DETAILED DESCRIPTION

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more apparent, various embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in various embodiments of the present invention to help readers better understand the present invention. However, even without these technical details and various variations and modifications based on the following embodiments, the technical solutions claimed in the present invention can still be implemented.

[0051] In the embodiments of the present invention, terms such as "upper," "lower," "left," "right," "front," "back," "top," "bottom," "inner," "outer," "center," "vertical," "horizontal," "transverse," and "longitudinal" to indicate directions or positions are based on the directions or positions shown in the accompanying drawings. These terms are primarily intended to better describe the present invention and its embodiments and are not intended to limit the devices, elements, or components indicated to having a specific direction, or to being constructed or operated in a specific direction.

[0052] Furthermore, some of the above terms may be used to express other meanings besides indicating a position or location. For example, the term "on" may also be used to indicate a dependency or connection in certain circumstances. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0053] Furthermore, the terms "installed," "set," "provided with," "opened," "connected," and "connected" should be interpreted broadly. For example, they can refer to fixed connections, removable connections, or integral structures; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; or internal communication between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0054] Furthermore, the terms "first," "second," etc., are primarily used to distinguish between different devices, elements, or components (which may or may not be of the same type and configuration), and are not intended to indicate or imply the relative importance or quantity of the devices, elements, or components indicated. Unless otherwise specified, "plurality" means two or more.

[0055] See Figure 1 、 5, 9, 13. The technical solution of the present invention provides a microscope objective lens 10, 20, 30, 40, which is composed of a first lens L1, a second lens L2, a third lens L3 with negative refractive power, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7 with positive refractive power, an eighth lens L8, a ninth lens L9, a tenth lens L10 with positive refractive power, an eleventh lens L11, a twelfth lens L12, a thirteenth lens L13 with positive refractive power, a fourteenth lens L14, a fifteenth lens L15, a sixteenth lens L16, a seventeenth lens L17, and an eighteenth lens L18, which are arranged in sequence from the exit side to the object side.

[0056] The focal lengths of the microscope objective lenses 10, 20, 30, and 40 are f, the combined focal length of the first lens L1 and the second lens L2 is f1-2, the focal length of the third lens L3 is f3, the combined focal length of the fourteenth lens L14, the fifteenth lens L15, and the sixteenth lens L16 is f14-15-16, the combined focal length of the seventeenth lens L17 and the eighteenth lens L18 is f17-18, the on-axis thickness of the seventeenth lens L17 is d33, and the on-axis thickness of the eighteenth lens L18 is d35. The on-axis distance from the object plane of the microscope objective lens 10 to the exit surface of the first lens L1 is TTL, that is, the total optical length is TTL. The image height of the microscope objective lens 10 is IH, and the following relationship is satisfied:

[0057] -3.10≤f1_2 / f3≤-1.80 (1)

[0058] 3.40≤f14_15_16 / f≤7.00 (2)

[0059] 4.00≤f17_18 / (d33+d35)≤120.00 (3)

[0060] 0.08≤IH*f / TTL≤0.09 (4)

[0061] Among them, the conditional expression (1) specifies the ratio of the combined focal length f1_2 of the combined lens composed of the first lens L1 and the second lens L2 to the focal length f3 of the third lens L3. Within the range specified by the conditional expression (1), it is beneficial to control the direction of light between the lenses and at the same time make the lens structure of the microscope objective lenses 10, 20, 30, and 40 compact.

[0062] Conditional equation (2) specifies the ratio of the combined focal length f14_15_16 of the lens group at the object side end of the microscope objective lenses 10, 20, 30, 40, which is composed of the fourteenth lens L14, the fifteenth lens L15, and the sixteenth lens L16, to the focal length f of the microscope objective lenses 10, 20, 30, 40. Within this limited range, sufficient light converging ability can be ensured.

[0063] Conditional formula (3) specifies a range of a ratio of the focal length to the thickness of the combined lens formed by the seventeenth lens L17 and the eighteenth lens L18. Within the range defined by conditional formula (3), the combined lens can maintain a reasonable thickness while having sufficient refractive power.

[0064] Conditional equation (4) defines the ratio range of the product of the image height IH and the focal length f of the microscope objective lens 10, 20, 30, 40 to its total optical length TTL. Within this range, the total optical length of the microscope objective lens 10, 20, 30, 40 can be controlled when the imaging range reaches the expected state.

[0065] In this solution, through the above settings, the direction of light between lenses can be controlled, which helps to ensure a smooth transition of the outgoing light, make the lens structure compact, and control the total length of the lens while ensuring that the imaging range reaches the expected state, so that the microscope objective has a large numerical aperture, ensuring that the light has sufficient convergence ability and excellent optical performance, meeting the design requirements of low distortion, 20x magnification, and long working distance.

[0066] It should be noted that the units of the above-mentioned focal length, thickness, image height and total optical length are millimeters.

[0067] Preferably, the curvature radius of the exit side surface of the tenth lens is R19, the curvature radius of the object side surface of the tenth lens is R20, and the following relationship is satisfied:

[0068] -1.60≤R19 / R20≤-2.50 (5)

[0069] Conditional formula (5) specifies the shape of the tenth lens L10, which helps to smoothly transition the outgoing light and improves the imaging quality.

[0070] Preferably, the on-axis distance from the object plane of the microscope objective lens to the object side surface of the eighteenth lens is WD, that is, the working distance is WD, and the numerical aperture NA of the microscope objective lens satisfies the following relationship:

[0071] WD*NA≥1.10 (6)

[0072] Conditional formula (6) specifies the product range of the working distance WD and the numerical aperture NA of the microscope objective lens 10, 20, 30, 40. By limiting its upper limit, the working distance WD of the microscope objective lens 10, 20, 30, 40 can be prevented from being too long relative to the numerical aperture NA, thereby achieving satisfactory aberration performance and high resolution. In addition, by limiting the lower limit of the above product, the working distance WD can be prevented from becoming too short, and the user does not have to pay too much attention to prevent the objective lens from colliding with the observed object, thereby improving the work efficiency when performing measurements. In particular, when using a microscope objective lens for observation, it is often necessary to use an objective lens with a low numerical aperture to observe an object with a very uneven surface. By limiting the lower limit of WD*NA, this solution can ensure that the low numerical aperture objective lens has a sufficiently long working distance. As a result, even an observed object with a large surface unevenness can be measured, thereby achieving high versatility of the microscope objective lens. In other words, within the range specified by conditional formula (6), it can be ensured that the microscope objective lens has sufficient resolution, high work efficiency, and high versatility.

[0073] In one embodiment, the exit side surface of the first lens L1 is convex at the paraxial position, and the object side surface is convex at the paraxial position. In other optional embodiments, the object side surface and the exit side surface of the first lens L1 can also be set to other concave and convex distributions.

[0074] Preferably, the radius of curvature of the exit side surface of the first lens is R1, the radius of curvature of the object side surface of the first lens is R2, the axial thickness of the first lens is d1, and the following relationship is satisfied:

[0075] -1.39≤(R1+R2) / (R1-R2)≤-0.24 (7)

[0076] 0.03≤d1 / TTL≤0.10 (8)

[0077] Conditional equation (7) specifies the shape of the first lens L1. Reasonable control of the shape of the first lens L1 can mitigate the degree of light deflection after passing through the first lens L1, effectively reducing aberrations. More preferably, -0.87 ≤ (R1 + R2) / (R1 - R2) ≤ -0.30. Conditional equation (8) specifies the range of the ratio of the on-axis thickness d1 of the first lens L1 to the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. Within this range, it is helpful to control the thickness of the first lens L1, and further control the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. More preferably, 0.05 ≤ d1 / TTL ≤ 0.08.

[0078] In one embodiment, the exit side surface of the second lens L2 is concave at the paraxial direction, and the object side surface of the second lens L2 is concave at the paraxial direction. In other optional embodiments, the object side surface and the exit side surface of the second lens L2 can also be configured with other concave or convex distributions.

[0079] Preferably, the radius of curvature of the exit side surface of the second lens is R3, the radius of curvature of the object side surface of the second lens is R4, the axial thickness of the second lens is d3, and the following relationship is satisfied:

[0080] 0.15≤(R3+R4) / (R3-R4)≤1.13 (9)

[0081] 0.01≤d3 / TTL≤0.06 (10)

[0082] Conditional equation (9) specifies the shape of the second lens. Within the range defined by conditional equation (9), the second lens L2 can effectively correct system spherical aberration. More preferably, 0.23 ≤ (R3 + R4) / (R3 - R4) ≤ 0.90. Conditional equation (10) specifies the range of the ratio of the on-axis thickness d3 of the second lens L2 to the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40, which helps to reasonably control the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. More preferably, 0.01 ≤ d3 / TTL ≤ 0.05.

[0083] Preferably, the object-side surface of the first lens L1 and the exit-side surface of the second lens L2 are cemented to form a combined lens with positive refractive power, and the following relationship is satisfied:

[0084] 1.93≤f1_2 / f≤8.42 (11)

[0085] In one embodiment, the exit side surface of the third lens L3 is concave or convex at the paraxial direction, and the object side surface thereof is concave at the paraxial direction. In other optional embodiments, the object side surface of the third lens L3 can also be set to be convex.

[0086] Preferably, the radius of curvature of the exit side surface of the third lens L3 is R5, the radius of curvature of the object side surface thereof is R6, the axial thickness of the third lens is d5, and the following relationship is satisfied:

[0087] 0.15≤(R5+R6) / (R5-R6)≤1.57 (12)

[0088] 0.01≤d5 / TTL≤0.03 (13)

[0089] -4.19≤f3 / f≤-1.24 (14)

[0090] Conditional equation (12) specifies the shape of the third lens L3, which helps reduce the aberrations of the microscope objective lenses 10, 20, 30, and 40. More preferably, 0.24 ≤ (R5 + R6) / (R5 - R6) ≤ 1.25. Conditional equation (13) specifies the range of the ratio of the on-axis thickness d15 of the third lens L3 to the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. Within this range, it is beneficial to control the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. More preferably, 0.01 ≤ d5 / TTL ≤ 0.02. Conditional equation (14) specifies the ratio of the focal length f3 of the third lens L3 to the focal length f of the microscope objective lenses 10, 20, 30, and 40. Within this range, it helps reduce aberrations and improve imaging quality. More preferably, -2.62 ≤ f3 / f ≤ -1.55.

[0091] In one embodiment, the exit side surface of the fourth lens L4 is concave at the paraxial direction, and the object side surface thereof is concave or convex at the paraxial direction. In other optional embodiments, the exit side surface of the fourth lens L4 can also be set to be convex.

[0092] Preferably, the radius of curvature of the exit side surface of the fourth lens L4 is R7, the radius of curvature of the object side surface of the fourth lens L4 is R8, the axial thickness of the fourth lens L4 is d7, and the following relationship is satisfied:

[0093] -2.94≤(R7+R8) / (R7-R8)≤-0.12 (15)

[0094] 0.01≤d7 / TTL≤0.06 (16)

[0095] Conditional equation (15) specifies the shape of the fourth lens L4, enabling the fourth lens L4 to effectively correct system spherical aberration. More preferably, -1.84 ≤ (R7 + R8) / (R7 - R8) ≤ -0.15. Conditional equation (16) specifies the range of the ratio of the on-axis thickness d7 of the fourth lens L4 to the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40, which is conducive to controlling the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. More preferably, 0.01 ≤ d7 / TTL ≤ 0.05.

[0096] In one embodiment, the exit side surface of the fifth lens L5 is convex or concave at the paraxial direction, and the object side surface thereof is convex at the paraxial direction. In other optional embodiments, the object side surface of the fifth lens L5 can also be set to be concave.

[0097] Preferably, the radius of curvature of the exit side surface of the fifth lens L5 is R9, the radius of curvature of the object side surface of the fifth lens L5 is R10, the axial thickness of the fifth lens is d9, and the following relationship is satisfied:

[0098] 0.11≤(R9+R10) / (R9-R10)≤2.20 (17)

[0099] 0.04≤d9 / TTL≤0.15 (18)

[0100] Conditional formula (17) specifies the shape of the fifth lens L5. Within this range, it is helpful to reduce the spherical aberration of the microscope objective lenses 10, 20, 30, and 40 and improve the imaging quality. More preferably, 0.18≤(R9+R10) / (R9-R10)≤1.76. Conditional formula (18) specifies the ratio range of the on-axis thickness d9 of the fifth lens d9 to the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. Within the range defined by conditional formula (18), it is helpful to reasonably control the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. More preferably, 0.06≤d9 / TTL≤0.12.

[0101] In one embodiment, the exit side surface of the sixth lens L6 is concave at the paraxial direction, and the object side surface of the sixth lens L6 is convex at the paraxial direction. In other optional embodiments, the object side surface and the exit side surface of the sixth lens L6 can also be configured with other concave and convex distributions.

[0102] Preferably, the radius of curvature of the exit side surface of the sixth lens L6 is R11, the radius of curvature of the object side surface of the sixth lens L6 is R12, and the on-axis thickness of the sixth lens L6 is d11, and the following relationship is satisfied:

[0103] -10.75≤(R11+R12) / (R11-R12)≤-2.17 (19)

[0104] 0.01≤d11 / TTL≤0.03 (20)

[0105] Conditional equation (19) specifies the shape of the sixth lens L6. Reasonable control of the shape of the sixth lens L6 is beneficial for correcting off-axis aberrations and other issues. More preferably, -6.72 ≤ (R11 + R12) / (R11 - R12) ≤ -2.71. Conditional equation (20) specifies the on-axis thickness d11 of the sixth lens L6. Within the range defined by conditional equation (20), the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be effectively controlled. More preferably, 0.02 ≤ d11 / TTL ≤ 0.03.

[0106] Preferably, the object-side surface of the fourth lens L4 is cemented to the exit-side surface of the fifth lens L5, and the object-side surface of the fifth lens L5 is cemented to the exit-side surface of the sixth lens L6, so as to form a combined lens with negative refractive power. The combined focal length of the fourth lens L4, the fifth lens L5, and the sixth lens L6 is f4-5-6, and satisfies the following relationship:

[0107] -7.70≤f4_5_6 / f≤-1.41 (21)

[0108] Conditional formula (21) specifies the ratio range of the combined focal length of the combined lens composed of the fourth lens L4, the fifth lens L5 and the sixth lens L6 to the focal length f of the microscope objective lenses 10, 20, 30, and 40. Within the above range, the optical performance of the microscope objective lenses 10, 20, 30, and 40 can be improved. More preferably, -4.81≤f4_5_6 / f≤-1.77.

[0109] In one embodiment, the exit side surface of the seventh lens L7 is concave or convex at the paraxial direction, and the object side surface thereof is convex at the paraxial direction. In other optional embodiments, the object side surface of the seventh lens L7 can also be set to be concave.

[0110] Preferably, the radius of curvature of the exit side surface of the seventh lens L7 is R13, the radius of curvature of the object side surface of the seventh lens L7 is R14, the axial thickness of the seventh lens L7 is d13, and the focal length of the seventh lens L7 is f7, and the following relationship is satisfied:

[0111] 0.41≤(R13+R14) / (R13-R14)≤2.60 (22)

[0112] 0.02≤d13 / TTL≤0.09 (23)

[0113] 2.16≤f7 / f≤7.34 (24)

[0114] Conditional equation (22) specifies the shape of the seventh lens L7. Within the range of the conditional equation, the seventh lens L7 can effectively correct the system spherical aberration, which helps to improve the imaging quality. More preferably, 0.66≤(R13+R14) / (R13-R14)≤2.08. Conditional equation (23) specifies the axial thickness d13 of the seventh lens L7. Within this range, it helps to shorten the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. More preferably, 0.04≤d13 / TTL≤0.07. Conditional equation (24) specifies the ratio of the focal length f7 of the seventh lens L7 to the focal length f of the microscope objective lenses 10, 20, 30, and 40. Within the range of the conditional equation, it helps to reduce aberrations and improve the imaging quality. More preferably, 3.46≤f7 / f≤5.87.

[0115] In one embodiment, the exit side surface of the eighth lens L8 is convex at the paraxial direction, and the object side surface of the eighth lens L8 is convex at the paraxial direction. In other optional embodiments, the object side surface and the exit side surface of the eighth lens L8 can also be set to other concave and convex distributions.

[0116] Preferably, the radius of curvature of the exit side surface of the eighth lens L8 is R15, the radius of curvature of the object side surface of the eighth lens L8 is R16, and the on-axis thickness of the eighth lens L8 is d15, and the following relationship is satisfied:

[0117] 0.19≤(R15+R16) / (R15-R16)≤1.15 (25)

[0118] 0.05≤d15 / TTL≤0.16 (26)

[0119] Conditional equation (25) specifies the shape of the eighth lens element L8. Within the range specified by the conditional equation, the degree of light refraction passing through the eighth lens element L8 can be mitigated, effectively reducing aberrations. More preferably, 0.30 ≤ (R15 + R16) / (R15 - R16) ≤ 0.92. Conditional equation (26) specifies the on-axis thickness d15 of the eighth lens element L8. Within this range, this helps to shorten the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. More preferably, 0.08 ≤ d15 / TTL ≤ 0.13.

[0120] In one embodiment, the exit side surface of the ninth lens L9 is concave at the paraxial direction, and the object side surface thereof is convex at the paraxial direction. In other optional embodiments, the object side surface and the exit side surface of the ninth lens L9 can also be configured to have other concave and convex distributions.

[0121] Preferably, the radius of curvature of the exit side surface of the ninth lens L9 is R17, the radius of curvature of the object side surface of the ninth lens L9 is R18, and the on-axis thickness of the ninth lens L9 is d17, and the following relationship is satisfied:

[0122] -5.69≤(R17+R18) / (R17-R18)≤-0.82 (27)

[0123] 0.01≤d17 / TTL≤0.04 (28)

[0124] Conditional formula (27) specifies the shape of the ninth lens L9. Within the range specified by the conditional formula, the optical performance of the microscope objective lenses 10, 20, 30, and 40 is improved. More preferably, -3.56 ≤ (R17 + R18) / (R17 - R18) ≤ -1.02. Conditional formula (28) specifies the ratio of the thickness d17 of the ninth lens L9 to the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. Within the range specified by the conditional formula, the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 is reasonably controlled. More preferably, 0.02 ≤ d17 / TTL ≤ 0.03.

[0125] Preferably, the object-side surface of the eighth lens L8 is cemented to the exit-side surface of the ninth lens L9 to form a combined lens with positive refractive power. The combined focal length of the eighth lens L8 and the ninth lens L9 is f8-9, and the following relationship is satisfied:

[0126] 4.08≤f8_9 / f≤84.27 (29)

[0127] Conditional formula (29) specifies the ratio of the focal length f8_9 of the combined lens formed by the eighth lens L8 and the ninth lens L9 to the focal length f of the microscope objective lenses 10, 20, 30, and 40. In this way, the optical performance of the microscope objective lenses 10, 20, 30, and 40 can be improved. More preferably, 6.53≤f8_9 / f≤67.42.

[0128] In one embodiment of the present invention, the exit side surface of the tenth lens L10 is convex at the paraxial direction, and the object side surface of the tenth lens L10 is convex at the paraxial direction. In other optional embodiments, the object side surface and the exit side surface of the tenth lens L10 can also be configured with other concave and convex distributions.

[0129] Preferably, the radius of curvature of the exit side surface of the tenth lens L10 is R19, the radius of curvature of the object side surface of the tenth lens L10 is R20, the on-axis thickness of the tenth lens is d19, the focal length of the tenth lens is f10, and the following relationship is satisfied:

[0130] -1.10≤(R19+R20) / (R19-R20)≤0.31 (30)

[0131] 0.03≤d19 / TTL≤0.11 (31)

[0132] 2.38≤f10 / f≤12.26 (32)

[0133] Conditional formula (30) specifies the shape of the tenth lens L10. Within this range, the degree of deflection of light after passing through the first lens L1 can be alleviated, effectively reducing aberrations. More preferably, -0.69≤(R19+R20) / (R19-R20)≤0.25. Conditional formula (31) specifies the on-axis thickness d19 of the tenth lens L10, which helps to shorten the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. More preferably, 0.06≤d19 / TTL≤0.12. Conditional formula (32) specifies the range of the ratio of the focal length of the tenth lens L10 to the focal length f of the microscope objective lenses 10, 20, 30, and 40, which helps to reduce aberrations and improve imaging quality. More preferably, 3.81≤f10 / f≤9.81.

[0134] In this embodiment, the exit side surface of the eleventh lens L11 is convex at the paraxial direction, and the object side surface of the eleventh lens L11 is convex at the paraxial direction. In other optional embodiments, the object side surface and the exit side surface of the tenth lens L10 can also be configured with other concave and convex distributions.

[0135] Preferably, the radius of curvature of the exit side surface of the eleventh lens L11 is R21, the radius of curvature of the object side surface of the eleventh lens L11 is R22, and the on-axis thickness of the eleventh lens L11 is d21, and the following relationship is satisfied:

[0136] 0.02≤(R21+R22) / (R21-R22)≤1.02 (33)

[0137] 0.03≤d21 / TTL≤0.13 (34)

[0138] Conditional equation (33) specifies the shape of the eleventh lens L11. Within the range specified by the conditional equation, the degree of light refraction passing through the eleventh lens L11 can be mitigated, effectively reducing aberrations. More preferably, 0.04 ≤ (R21 + R22) / (R21 - R22) ≤ 0.81. Conditional equation (34) specifies the on-axis thickness d21 of the eleventh lens L11, which can effectively shorten the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40, making the structures of the microscope objective lenses 10, 20, 30, and 40 compact. More preferably, 0.04 ≤ d21 / TTL ≤ 0.11.

[0139] In one embodiment, the exit side surface of the twelfth lens L12 is concave at the paraxial direction, and the object side surface of the twelfth lens L12 is concave or convex at the paraxial direction. In other feasible embodiments, the exit side surface of the twelfth lens L12 can also be set to be convex.

[0140] Preferably, the radius of curvature of the exit side surface of the twelfth lens L12 is R23, the radius of curvature of the object side surface of the twelfth lens L12 is R24, and the axial thickness of the twelfth lens L12 is d23, and the following relationship is satisfied:

[0141] -2.18≤(R23+R24) / (R23-R24)≤-0.29 (35)

[0142] 0.01≤d23 / TTL≤0.04 (36)

[0143] Conditional equation (35) specifies the shape of the twelfth lens L12, enabling it to effectively correct system spherical aberration. More preferably, -1.37 ≤ (R23 + R24) / (R23 - R24) ≤ -0.36. Conditional equation (36) specifies the on-axis thickness d23 of the twelfth lens L12. Within this range, it helps control the total optical length TTL of the microscope objective 10. More preferably, 0.02 ≤ d23 / TTL ≤ 0.03.

[0144] Preferably, the object-side surface of the eleventh lens L11 and the exit-side surface of the twelfth lens L12 are cemented to form a combined lens with negative refractive power. The combined focal length of the eleventh lens L11 and the twelfth lens L12 is f11-12, and satisfies the following relationship:

[0145] -879.88≤f11_12 / f≤-5.21 (37)

[0146] Conditional formula (37) specifies the ratio range of the combined focal length f11_12 of the combined lens composed of the eleventh lens L11 and the twelfth lens L12 to the focal length f of the microscope objective lenses 10, 20, 30, and 40, which helps to improve the optical performance of the microscope objective lenses 10, 20, 30, and 40. More preferably, -549.93≤f11_12 / f≤-6.51.

[0147] In one embodiment, the exit side surface of the thirteenth lens L13 is convex at the paraxial direction, and the object side surface of the thirteenth lens L13 is concave or convex at the paraxial direction. In other optional embodiments, the exit side surface of the thirteenth lens L13 can also be set to be concave.

[0148] Preferably, the radius of curvature of the exit side surface of the thirteenth lens L13 is R25, the radius of curvature of the object side surface of the thirteenth lens L13 is R26, the on-axis thickness of the thirteenth lens L13 is d25, and the focal length of the thirteenth lens L13 is f13, and the following relationship is satisfied:

[0149] -3.04≤(R25+R26) / (R25-R26)≤-0.53 (38)

[0150] 0.03≤d25 / TTL≤0.10 (39)

[0151] 1.68≤f13 / f≤7.42 (40)

[0152] Conditional formula (38) specifies the shape of the thirteenth lens L13. Within this range, the spherical aberration of the microscope objective lenses 10, 20, 30, and 40 can be reduced. More preferably, -1.90≤(R25+R26) / (R25-R26)≤-0.66. Conditional formula (39) specifies the on-axis thickness d25 of the thirteenth lens L13. Within this range, it is beneficial to effectively compress the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. More preferably, 0.05≤d25 / TTL≤0.08. Conditional formula (40) specifies the range of the ratio of the focal length f13 of the thirteenth lens L13 to the focal length f of the microscope objective lenses 10, 20, 30, and 40, which helps to reduce aberrations and improve imaging quality. More preferably, 2.69≤f13 / f≤5.93.

[0153] In one embodiment, the exit side surface of the fourteenth lens L14 is convex at the paraxial direction, and the object side surface of the fourteenth lens L14 is convex at the paraxial direction. In other optional embodiments, the exit side surface and object side surface of the fourteenth lens L14 can also be configured with other concave and convex distributions.

[0154] Preferably, the radius of curvature of the exit side surface of the fourteenth lens L14 is R27, the radius of curvature of the object side surface of the fourteenth lens L14 is R28, and the on-axis thickness of the fourteenth lens L14 is d27, and the following relationship is satisfied:

[0155] -1.06≤(R27+R28) / (R27-R28)≤-0.27 (41)

[0156] 0.04≤d27 / TTL≤0.13 (42)

[0157] Conditional equation (41) specifies the shape of the fourteenth lens L14. Within the above range, the fourteenth lens L14 can effectively correct system spherical aberration. More preferably, -0.66 ≤ (R27 + R28) / (R27 - R28) ≤ -0.34. Conditional equation (42) specifies the on-axis thickness d27 of the fourteenth lens L14, which helps to shorten the total optical length TTL of the microscope objective lens 10, 20, 30, or 40. More preferably, 0.07 ≤ d27 / TTL ≤ 0.10.

[0158] In one embodiment, the exit side surface of the fifteenth lens L15 is concave at the paraxial direction, and the object side surface of the fifteenth lens L15 is concave at the paraxial direction. In other optional embodiments, the exit side surface and object side surface of the fifteenth lens L15 can also be configured with other concave or convex distributions.

[0159] Preferably, the radius of curvature of the exit side surface of the fifteenth lens L15 is R29, the radius of curvature of the object side surface of the fifteenth lens L15 is R30, and the axial thickness of the fifteenth lens L15 is d29, and the following relationship is satisfied:

[0160] -0.05≤(R29+R30) / (R29-R30)≤0.98 (43)

[0161] 0.01≤d29 / TTL≤0.03 (44)

[0162] Conditional equation (43) specifies the shape of the fifteenth lens L15. Within this range, the degree of light refraction passing through the fifteenth lens L15 can be mitigated, effectively reducing aberrations. More preferably, -0.03 ≤ (R29 + R30) / (R29 - R30) ≤ 0.79. Conditional equation (44) specifies the on-axis thickness d29 of the fifteenth lens L15, which helps to shorten the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. More preferably, 0.01 ≤ d29 / TTL ≤ 0.02.

[0163] In one embodiment, the exit side surface of the sixteenth lens L16 is convex at the paraxial position, and the object side surface of the sixteenth lens L16 is convex at the paraxial position. In other optional embodiments, the exit side surface and object side surface of the sixteenth lens L16 can also be configured with other concave and convex distributions.

[0164] Preferably, the radius of curvature of the exit side surface of the sixteenth lens L16 is R31, the radius of curvature of the object side surface of the sixteenth lens L16 is R32, and the on-axis thickness of the sixteenth lens L16 is d31, and the following relationship is satisfied:

[0165] -1.45≤(R31+R32) / (R31-R32)≤-0.29 (45)

[0166] 0.02≤d31 / TTL≤0.09 (46)

[0167] Conditional equation (45) specifies the shape of the sixteenth lens L16. Within this range, the degree of light refraction passing through the sixteenth lens L16 can be mitigated, effectively reducing aberrations. More preferably, -0.91 ≤ (R31 + R32) / (R31 - R32) ≤ -0.36. Conditional equation (46) specifies the on-axis thickness d31 of the sixteenth lens L16. Within the above range, the optical performance of the microscope objective lenses 10, 20, 30, and 40 can be improved. More preferably, 0.03 ≤ d31 / TTL ≤ 0.07.

[0168] In one solution, the object-side surface of the fourteenth lens L14 is cemented to the exit side surface of the fifteenth lens L15, and the object-side surface of the fifteenth lens L15 is cemented to the exit side surface of the sixteenth lens L16 to form a combined lens with positive refractive power.

[0169] In one embodiment, the exit side surface of the seventeenth lens L17 is convex at the paraxial direction, and the object side surface of the seventeenth lens L17 is convex at the paraxial direction. In other optional embodiments, the exit side surface and object side surface of the seventeenth lens L17 can also be configured with other concave and convex distributions.

[0170] Preferably, the radius of curvature of the exit side surface of the seventeenth lens L17 is R33, the radius of curvature of the object side surface of the seventeenth lens L17 is R34, and the on-axis thickness of the seventeenth lens L17 is d33, and the following relationship is satisfied:

[0171] -1.08≤(R33+R34) / (R33-R34)≤-0.17 (47)

[0172] 0.02≤d33 / TTL≤0.08 (48)

[0173] Conditional formula (47) specifies the shape of the seventeenth lens L17. Within this range, the optical performance and imaging quality of the microscope objective lens 10 can be improved. More preferably, -0.67 ≤ (R33 + R34) / (R33 - R34) ≤ -0.22. Conditional formula (48) specifies the ratio range of the on-axis thickness d33 of the seventeenth lens L17 to the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40, which is conducive to controlling the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. More preferably, 0.04 ≤ d33 / TTL ≤ 0.06.

[0174] In one embodiment, the exit side surface of the eighteenth lens L18 is concave at the paraxial direction, and the object side surface of the eighteenth lens L18 is concave at the paraxial direction. In other optional embodiments, the exit side surface and object side surface of the eighteenth lens L18 can also be configured with other concave or convex distributions.

[0175] Preferably, the radius of curvature of the exit side surface of the eighteenth lens L18 is R35, the radius of curvature of the object side surface of the eighteenth lens L18 is R36, and the on-axis thickness of the eighteenth lens L18 is d35, and the following relationship is satisfied:

[0176] 0.25≤(R35+R36) / (R35-R36)≤0.93 (49)

[0177] 0.01≤d35 / TTL≤0.04 (50)

[0178] Conditional equation (49) specifies the shape of the eighteenth lens L18. Within this range, the degree of light refraction passing through the eighteenth lens L18 can be mitigated, effectively reducing aberrations. More preferably, 0.40 ≤ (R35 + R36) / (R35 - R36) ≤ 0.74. Conditional equation (50) specifies the on-axis thickness d35 of the eighteenth lens L18. Within the above range, this helps to shorten the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. More preferably, 0.01 ≤ d35 / TTL ≤ 0.03.

[0179] In this solution, the exit side surface of the seventeenth lens L17 and the object side surface of the eighteenth lens L18 are cemented to form a combined lens with positive refractive power, and the combined focal length f17_18 of the combined lens also satisfies the following relationship:

[0180] 1.30≤f17_18 / f≤81.29 (51)

[0181] Within the conditional range defined by conditional expression (51), the optical performance of the microscope objective lenses 10, 20, 30, and 40 can be improved. More preferably, 2.08≤f17_18 / f≤65.03.

[0182] In this embodiment, an optical element such as an optical filter GF is provided on the object side of the eighteenth lens L18, wherein the optical filter GF can be a glass cover or an optical filter. Figure 1 In other solutions, the optical filter GF can also be set at other positions.

[0183] The microscope objective lenses 10, 20, 30, and 40 of the present invention can control the direction of light between lenses, making the lens structure compact, controlling the total length of the lens while ensuring that the imaging range reaches the expected state, so that the microscope objective lenses have a large numerical aperture, ensuring that the light has sufficient convergence ability, and have excellent optical performance, meeting the design requirements of low distortion, 20x magnification, and long working distance.

[0184] The microscope objective lens 10 of the present invention will be described below using examples. The symbols recorded in each example are as shown in Table [1], and the units of focal length, on-axis distance, curvature radius, on-axis thickness, inflection point position, and stationary point position are millimeters.

[0185] TTL: total optical length (the on-axis distance from the object side of the first lens L1 to the imaging surface), in millimeters.

[0186] First embodiment:

[0187] The exit-side surface of the first lens L1 is convex at the paraxial direction, and the object-side surface thereof is also convex at the paraxial direction.

[0188] The exit-side surface of the second lens L2 is concave at the paraxial direction, and the object-side surface thereof is also concave at the paraxial direction.

[0189] The third lens L3 has negative refractive power, and its exit-side surface is concave at the paraxial direction, and its object-side surface is also concave at the paraxial direction.

[0190] The exit-side surface of the fourth lens L4 is concave at the paraxial direction, and the object-side surface thereof is also concave at the paraxial direction.

[0191] The exit-side surface of the fifth lens L5 is convex at the paraxial direction, and the object-side surface thereof is also convex at the paraxial direction.

[0192] The exit-side surface of the sixth lens L6 is concave at the paraxial direction, and the object-side surface thereof is convex at the paraxial direction.

[0193] The seventh lens L7 has positive refractive power, and its exit-side surface and paraxial portion are convex, and its object-side surface and paraxial portion are convex.

[0194] The exit-side surface of the eighth lens L8 is convex at the paraxial direction, and the object-side surface thereof is also convex at the paraxial direction.

[0195] The exit side surface of the ninth lens L9 is concave at the paraxial direction, and the object side surface thereof is convex at the paraxial direction.

[0196] The tenth lens L10 has positive refractive power, and its exit-side surface is convex at the paraxial direction, and its object-side surface is convex at the paraxial direction.

[0197] The eleventh lens L11 has an exit-side surface that is convex at the paraxial direction, and a paraxial-side surface that is convex at the object-side surface.

[0198] The emitting side surface of the twelfth lens L12 is concave at the paraxial position, and the object side surface thereof is also concave at the paraxial position.

[0199] The thirteenth lens L13 has positive refractive power, its exit-side surface is convex at the paraxial direction, and its object-side surface is concave at the paraxial direction.

[0200] The exit-side surface of the fourteenth lens L14 is convex at the paraxial direction, and the object-side surface thereof is also convex at the paraxial direction.

[0201] The exit side surface of the fifteenth lens L15 is concave at the paraxial position, and the object side surface thereof is also concave at the paraxial position.

[0202] The exit-side surface of the sixteenth lens L16 is convex at the paraxial position, and the object-side surface thereof is also convex at the paraxial position.

[0203] The exit-side surface of the seventeenth lens L17 is convex at the paraxial direction, and the object-side surface thereof is also convex at the paraxial direction.

[0204] The exit-side surface of the eighteenth lens L18 is concave at the paraxial position, and the object-side surface thereof is also concave at the paraxial position.

[0205] Figure 1 1 is a schematic structural diagram of the microscope objective lens 10 in the first embodiment. The following shows design data of the microscope objective lens 10 in the first embodiment of the present invention.

[0206] Table 1 lists the curvature radius R of the exit and object side surfaces of the first through eighteenth lenses L1 through L18, which constitute the microscope objective 10 in the first embodiment of the present invention, the on-axis thickness of the lenses, the on-axis distance d between the lenses, the refractive index nd, and the Abbe number vd. It should be noted that in this embodiment, the units of distance, radius, and thickness are all in millimeters (mm).

[0207]

Table 1

[0208]

[0209]

[0210] The meanings of the symbols in the above table are as follows.

[0211] R: radius of curvature of the optical surface, or the center radius of curvature for a lens; ST: aperture;

[0212] R1: the radius of curvature of the exit side of the first lens L1;

[0213] R2: the radius of curvature of the object-side surface of the first lens L1;

[0214] R3: radius of curvature of the exit side of the second lens L2;

[0215] R4: radius of curvature of the object-side surface of the second lens L2;

[0216] R5: radius of curvature of the exit side of the third lens L3;

[0217] R6: radius of curvature of the object-side surface of the third lens L3;

[0218] R7: radius of curvature of the exit side of the fourth lens L4;

[0219] R8: radius of curvature of the object-side surface of the fourth lens L4;

[0220] R9: radius of curvature of the exit side of the fifth lens L5;

[0221] R10: radius of curvature of the object-side surface of the fifth lens L5;

[0222] R11: radius of curvature of the exit side surface of the sixth lens L6;

[0223] R12: radius of curvature of the object-side surface of the sixth lens L6;

[0224] R13: radius of curvature of the exit side surface of the seventh lens L7;

[0225] R14: radius of curvature of the object-side surface of the seventh lens L7;

[0226] R15: radius of curvature of the exit side surface of the eighth lens L8;

[0227] R16: radius of curvature of the object-side surface of the eighth lens L8;

[0228] R17: radius of curvature of the exit side surface of the ninth lens L9;

[0229] R18: radius of curvature of the object-side surface of the ninth lens L9;

[0230] R19: radius of curvature of the exit side surface of the tenth lens L10;

[0231] R20: radius of curvature of the object-side surface of the tenth lens L10;

[0232] R21: the curvature radius of the exit side surface of the eleventh lens L11;

[0233] R22: the radius of curvature of the object-side surface of the eleventh lens L11;

[0234] R23: radius of curvature of the exit side surface of the twelfth lens L12;

[0235] R24: radius of curvature of the object-side surface of the twelfth lens L12;

[0236] R25: radius of curvature of the exit side surface of the thirteenth lens L13;

[0237] R26: radius of curvature of the object-side surface of the thirteenth lens L13;

[0238] R27: radius of curvature of the exit side surface of the fourteenth lens L14;

[0239] R28: radius of curvature of the object-side surface of the fourteenth lens L14;

[0240] R29: radius of curvature of the exit side surface of the fifteenth lens L15;

[0241] R30: radius of curvature of the object-side surface of the fifteenth lens L15;

[0242] R31: radius of curvature of the exit side surface of the sixteenth lens L16;

[0243] R32: radius of curvature of the object-side surface of the sixteenth lens L16;

[0244] R33: radius of curvature of the exit side surface of the seventeenth lens L17;

[0245] R34: radius of curvature of the object-side surface of the seventeenth lens L17;

[0246] R35: the radius of curvature of the exit side surface of the eighteenth lens L18;

[0247] R36: radius of curvature of the object-side surface of the eighteenth lens L18;

[0248] d: the on-axis thickness of the lens and the on-axis distance between lenses;

[0249] d1: axial thickness of the first lens L1;

[0250] d2: the on-axis distance from the exit side of the first lens L1 to the object-side surface of the second lens L2; ​​d3: the on-axis thickness of the second lens L2;

[0251] d4: the on-axis distance from the exit side of the second lens L2 to the object-side surface of the third lens L3; d5: the on-axis thickness of the third lens L3;

[0252] d6: the on-axis distance from the exit side of the third lens L3 to the object-side surface of the fourth lens L4; d7: the on-axis thickness of the fourth lens L4;

[0253] d8: the on-axis distance from the exit side of the fourth lens L4 to the object-side surface of the fifth lens L5; d9: the on-axis thickness of the fifth lens L5;

[0254] d10: the axial distance between the exit side of the fifth lens L5 and the object-side surface of the sixth lens L6;

[0255] d11: axial thickness of sixth lens L6;

[0256] d12: the axial distance between the exit side of the sixth lens L6 and the object side of the seventh lens L7;

[0257] d13: axial thickness of seventh lens L7;

[0258] d141: the on-axis distance between the exit side of the seventh lens L7 and the aperture ST;

[0259] d142: the on-axis distance from the aperture ST to the object-side surface of the eighth lens L8;

[0260] d15: axial thickness of the eighth lens L8;

[0261] d16: the axial distance between the exit side of the eighth lens L8 and the object side of the ninth lens L9;

[0262] d17: axial thickness of the ninth lens L9;

[0263] d18: the axial distance between the exit side surface of the ninth lens L9 and the object side surface of the tenth lens L10;

[0264] d19: axial thickness of the tenth lens L10;

[0265] d20: the on-axis distance between the exit side surface of the tenth lens L10 and the object-side surface of the eleventh lens L11; d21: the on-axis thickness of the eleventh lens L11;

[0266] d22: the on-axis distance from the exit side of the eleventh lens L11 to the object-side surface of the twelfth lens L12; d23: the on-axis thickness of the twelfth lens L12;

[0267] d24: the on-axis distance between the exit side surface of the twelfth lens L12 and the object-side surface of the thirteenth lens L13; d25: the on-axis thickness of the thirteenth lens L13;

[0268] d26: the on-axis distance between the exit side surface of the thirteenth lens L13 and the object-side surface of the fourteenth lens L14; d27: the on-axis thickness of the fourteenth lens L14;

[0269] d28: the on-axis distance between the exit side surface of the fourteenth lens L14 and the object side surface of the fifteenth lens L15; d29: the on-axis distance between the fifteenth lens L15;

[0270] d30: the on-axis distance between the exit side surface of the fifteenth lens L15 and the object-side surface of the sixteenth lens L16; d31: the on-axis thickness of the sixteenth lens L16;

[0271] d32: the on-axis distance from the exit side surface of the sixteenth lens L16 to the object-side surface of the seventeenth lens L17; d33: the on-axis thickness of the seventeenth lens L17;

[0272] d34: the on-axis distance between the exit side surface of the seventeenth lens L17 and the object-side surface of the eighteenth lens L18; d35: the on-axis thickness of the eighteenth lens L18;

[0273] d36: the on-axis distance between the exit side of the eighteenth lens L18 and the object plane;

[0274] nd: refractive index of d-line (d-line is green light with a wavelength of 555nm);

[0275] nd1: the refractive index of the first lens L1 at the d-line;

[0276] nd2: the refractive index of the second lens L2 at the d-line;

[0277] nd3: the refractive index of the third lens L3 at the d-line;

[0278] nd4: the refractive index of the fourth lens L4 at the d-line;

[0279] nd5: the refractive index of the fifth lens L5 at the d-line;

[0280] nd6: the refractive index of the sixth lens L6 at the d-line;

[0281] nd7: the refractive index of the seventh lens L7 at the d-line;

[0282] nd8: the refractive index of the eighth lens L8 at the d-line;

[0283] nd9: the refractive index of the ninth lens L9 at the d-line;

[0284] nd10: the refractive index of the d-line of the tenth lens L10;

[0285] nd11: the refractive index of the d-line of the eleventh lens L11;

[0286] nd12: the refractive index of the d-line of the twelfth lens L12;

[0287] nd13: the refractive index of the thirteenth lens L13 at the d-line;

[0288] nd14: the refractive index of the d-line of the fourteenth lens L14;

[0289] nd15: the refractive index of the d-line of the fifteenth lens L15;

[0290] nd16: refractive index of the d-line of the sixteenth lens L16;

[0291] nd17: the refractive index of the seventeenth lens L17 at the d-line;

[0292] nd18: the refractive index of the eighteenth lens L18 at the d-line;

[0293] vd: Abbe number;

[0294] vd1: Abbe number of the first lens L1;

[0295] vd2: Abbe number of the second lens L2;

[0296] vd3: Abbe number of the third lens L3;

[0297] vd4: Abbe number of the fourth lens L4;

[0298] vd5: Abbe number of the fifth lens L5;

[0299] vd6: Abbe number of sixth lens L6;

[0300] vd7: Abbe number of seventh lens L7;

[0301] vd8: Abbe number of the eighth lens L8;

[0302] vd9: Abbe number of the ninth lens L9;

[0303] vd10: Abbe number of the tenth lens L10;

[0304] vd11: Abbe number of the eleventh lens L11;

[0305] vd12: Abbe number of the twelfth lens L12;

[0306] vd13: Abbe number of the thirteenth lens L13;

[0307] vd14: Abbe number of the fourteenth lens L14;

[0308] vd15: Abbe number of the fifteenth lens L15;

[0309] vd16: Abbe number of the sixteenth lens L16;

[0310] vd17: Abbe number of the seventeenth lens L17;

[0311] vd18: Abbe number of the eighteenth lens L18.

[0312] In addition, the following Table 5 also lists the values ​​corresponding to the various parameters in the first embodiment and the parameters specified in the conditional expressions.

[0313] Figure 2 FIG. 1 shows a schematic diagram of field curvature and distortion of light having a wavelength of 588 nanometers after passing through the microscope objective lens 10 of the first embodiment. Figure 2 The field curvature S is the field curvature in the sagittal direction, and T is the field curvature in the meridional direction; Figure 3 Schematic diagram showing chromatic aberration of magnification at wavelengths of 500 nm, 588 nm, 685 nm, 770 nm, and 830 nm after passing through the microscope objective lens 10 of the first embodiment;

[0314] Figure 4Schematic diagram of axial aberration of light with wavelengths of 500 nm, 588 nm, 685 nm, 770 nm and 830 nm after passing through the microscope objective lens 10 of the first embodiment is shown.

[0315] As shown in Table 5, the first embodiment satisfies each conditional expression.

[0316] In this embodiment, the microscope objective lens 10 has an entrance pupil diameter of 15.202 mm, a full field of view image height of 0.65 mm, a working distance WD of 1.38 mm, and a numerical aperture NA of 0.85. The microscope objective lens 10 is capable of controlling the trajectory of light between lenses, facilitating a smooth transition of emitted light and achieving a compact lens structure. While ensuring that the imaging range reaches the desired state, the overall length of the microscope objective lens 10 is controlled, resulting in a large numerical aperture, sufficient light convergence capability, and excellent optical performance, meeting the design requirements of low distortion, a 20x magnification, and a long working distance.

[0317] Second embodiment:

[0318] Figure 5 2 is a schematic structural diagram of the microscope objective lens 20 in the second embodiment. The second embodiment is substantially the same as the first embodiment, and the meanings of the symbols are the same as those in the first embodiment. Only the differences are listed below.

[0319] Table 2 shows design data of the microscope objective lens 20 according to the second embodiment of the present invention.

[0320]

Table 2

[0321]

[0322]

[0323] In addition, the following Table 5 also lists the values ​​corresponding to the various parameters in the second embodiment and the parameters specified in the conditional expressions.

[0324] Figure 6 FIG2 shows a schematic diagram of field curvature and distortion of light having a wavelength of 588 nanometers after passing through the microscope objective lens 20 of the second embodiment. Figure 6 The field curvature S is the field curvature in the sagittal direction, and T is the field curvature in the meridional direction; Figure 7 Schematic diagram showing chromatic aberration of magnification at wavelengths of 500 nm, 588 nm, 685 nm, 770 nm, and 830 nm after passing through the microscope objective lens 20 of the second embodiment;

[0325] Figure 8 Schematic diagram of axial aberration of light with wavelengths of 500 nanometers, 588 nanometers, 685 nanometers, 770 nanometers and 830 nanometers after passing through the microscope objective lens 20 of the second embodiment is shown.

[0326] As shown in Table 5, the second embodiment satisfies each conditional expression.

[0327] In this embodiment, the microscope objective lens 20 has an entrance pupil diameter of 15.211 mm, a full field of view image height of 0.65 mm, a working distance (WD) of 1.30 mm, and a numerical aperture (NA) of 0.85. The microscope objective lens 20 is capable of controlling the trajectory of light between lenses, facilitating a smooth transition of emitted light and achieving a compact lens structure. While ensuring the desired imaging range, the overall length of the microscope objective lens 20 is controlled, resulting in a large numerical aperture, sufficient light convergence capability, and excellent optical performance, meeting the design requirements of low distortion, a 20x magnification, and a long working distance.

[0328] Third embodiment:

[0329] Figure 9 3 is a schematic structural diagram of the microscope objective lens 30 in the third embodiment. The third embodiment is substantially the same as the first embodiment, and the meanings of the symbols are the same as those in the first embodiment. Only the differences are listed below.

[0330] In this embodiment, the exit side surface of the third lens L3 is convex at the paraxial position;

[0331] The object-side surface of the fourth lens L4 is convex at the paraxial position;

[0332] The exit side surface of the fifth lens L5 is concave at the paraxial position;

[0333] The exit side surface of the seventh lens L7 is concave at the paraxial position.

[0334] The object-side surface of the twelfth lens L12 is convex at the paraxial position;

[0335] The object-side surface of the thirteenth lens L13 is convex at the paraxial position;

[0336] Table 3 shows design data of the microscope objective lens 30 according to the third embodiment of the present invention.

[0337]

Table 3

[0338]

[0339]

[0340] In addition, the following Table 5 also lists the values ​​corresponding to the various parameters in the third embodiment and the parameters specified in the conditional expressions.

[0341] Figure 10 FIG2 shows a schematic diagram of field curvature and distortion of light having a wavelength of 588 nanometers after passing through the microscope objective lens 30 of the third embodiment. Figure 10The field curvature S is the field curvature in the sagittal direction, and T is the field curvature in the meridional direction; Figure 11 Schematic diagram showing chromatic aberration of magnification at wavelengths of 500 nm, 588 nm, 685 nm, 770 nm, and 830 nm after passing through the microscope objective lens 30 of the third embodiment; Figure 12 Schematic diagram of axial aberration of light with wavelengths of 500 nm, 588 nm, 685 nm, 770 nm and 830 nm after passing through the microscope objective lens 30 of the third embodiment is shown.

[0342] As shown in Table 5, the third embodiment satisfies each conditional expression.

[0343] In this embodiment, the microscope objective lens 30 has an entrance pupil diameter of 15.301 mm, a full field of view image height of 0.65 mm, a working distance (WD) of 1.30 mm, and a numerical aperture (NA) of 0.85. The microscope objective lens 30 is capable of controlling the trajectory of light between lenses, facilitating a smooth transition of emitted light and achieving a compact lens structure. While ensuring the desired imaging range, the overall length of the microscope objective lens 30 is controlled, resulting in a large numerical aperture, sufficient light convergence capability, and excellent optical performance, meeting the design requirements of low distortion, a 20x magnification, and a long working distance.

[0344] Fourth embodiment:

[0345] Figure 13 3 is a schematic structural diagram of the microscope objective lens 40 in the fourth embodiment. The fourth embodiment is substantially the same as the first embodiment, and the meanings of the symbols are the same as those in the first embodiment. Only the differences are listed below.

[0346] In this embodiment, the object-side surface of the fourth lens L4 is convex at the paraxial position;

[0347] The exit side surface of the fifth lens L5 is concave at the paraxial position;

[0348] The exit side surface of the seventh lens L7 is concave at the paraxial position.

[0349] The object-side surface of the thirteenth lens L13 is convex at the paraxial position.

[0350] Table 4 shows design data of the microscope objective lens 40 according to the fourth embodiment of the present invention.

[0351]

Table 4

[0352]

[0353]

[0354] In addition, the following Table 5 also lists the values ​​corresponding to the various parameters in the fourth embodiment and the parameters specified in the conditional expressions.

[0355] Figure 14 FIG. 4 shows a schematic diagram of field curvature and distortion of light having a wavelength of 555 nanometers after passing through the microscope objective lens 40 of the fourth embodiment. Figure 14 The field curvature S is the field curvature in the sagittal direction, and T is the field curvature in the meridional direction; Figure 15 Schematic diagram showing chromatic aberration of magnification at wavelengths of 500 nm, 588 nm, 685 nm, 770 nm, and 830 nm after passing through the microscope objective lens 40 of the fourth embodiment; Figure 16 Schematic diagram of axial aberration of light with wavelengths of 500 nm, 588 nm, 685 nm, 770 nm and 830 nm after passing through the microscope objective lens 40 of the fourth embodiment is shown.

[0356] As shown in Table 5, the fourth embodiment satisfies each conditional expression.

[0357] In this embodiment, the microscope objective lens 40 has an entrance pupil diameter of 15.302 mm, a full field of view image height of 0.65 mm, a working distance (WD) of 1.30 mm, and a numerical aperture (NA) of 0.85. The microscope objective lens 40 is capable of controlling the trajectory of light between lenses, facilitating a smooth transition of emitted light and achieving a compact lens structure. While ensuring the desired imaging range, the overall length of the microscope objective lens 40 is controlled, resulting in a large numerical aperture, sufficient light convergence capability, and excellent optical performance, meeting the design requirements of low distortion, a 20x magnification, and a long working distance.

[0358] Table 5 lists the numerical values ​​corresponding to the conditional expressions in the comparative implementation scheme according to the above conditions.

[0359]

Table 5

[0360]

[0361]

[0362] The microscope objective lens provided in the embodiment of the present invention is introduced in detail above. Specific examples are used herein to illustrate the principles and embodiments of the present invention. The description of the above embodiments is only used to help understand the concept of the present invention. There may be changes in the specific implementation and scope of application. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A microscope objective lens, characterized in that: The microscope objective lens is composed of a first lens, a second lens, a third lens with negative refractive power, a fourth lens, a fifth lens, a sixth lens, a seventh lens with positive refractive power, an eighth lens, a ninth lens, a tenth lens with positive refractive power, an eleventh lens, a twelfth lens, a thirteenth lens with positive refractive power, a fourteenth lens, a fifteenth lens, a sixteenth lens, a seventeenth lens, and an eighteenth lens, which are arranged in sequence from the exit side to the object side; the focal length of the microscope objective lens is f, and the first lens and the second lens have a positive refractive power of The combined focal length is f1-2, the focal length of the third lens is f3, the combined focal length of the fourteenth lens, the fifteenth lens, and the sixteenth lens is f14-15-16, the combined focal length of the seventeenth lens and the eighteenth lens is f17-18, the on-axis thickness of the seventeenth lens is d33, the on-axis thickness of the eighteenth lens is d35, the on-axis distance from the object plane of the microscope objective lens to the exit surface of the first lens is TTL, the image height of the microscope objective lens is IH, and the following relationship is satisfied: -3.10≤f1_2 / f3≤-1.80; 3.40≤f14_15_16 / f≤7.00; 4.00≤f17_18 / (d33+d35)≤120.00; 0.08≤IH*f / TTL≤0.

09.

2. The microscope objective lens according to claim 1, characterized in that The curvature radius of the exit side surface of the tenth lens is R19, and the curvature radius of the object side surface of the tenth lens is R20, and the following relationship is satisfied: -1.60≤R19 / R20≤-2.

50.

3. The microscope objective lens according to claim 1, characterized in that The axial distance between the object plane of the microscope objective lens and the object side surface of the eighteenth lens is WD, and the numerical aperture NA of the microscope objective lens satisfies the following relationship: WD*NA≥1.

10.

4. The microscope objective lens according to claim 1, characterized in that The exit side surface of the first lens is convex at the paraxial position, and the object side surface of the first lens is convex at the paraxial position; the curvature radius of the exit side surface of the first lens is R1, the curvature radius of the object side surface of the first lens is R2, and the axial thickness of the first lens is d1, and the following relationship is satisfied: -1.39≤(R1+R2) / (R1-R2)≤-0.24; 0.03≤d1 / TTL≤0.

10.

5. The microscope objective lens according to claim 1, characterized in that The exit side surface of the second lens is concave at the paraxial position, and the object side surface of the second lens is concave at the paraxial position; the radius of curvature of the exit side surface of the second lens is R3, the radius of curvature of the object side surface of the second lens is R4, and the axial thickness of the second lens is d3, and the following relationship is satisfied: 0.15≤(R3+R4) / (R3-R4)≤1.13; 0.01≤d3 / TTL≤0.

06.

6. The microscope objective lens according to claim 1, characterized in that The object-side surface of the first lens and the exit-side surface of the second lens are cemented to form a combined lens with positive refractive power, and the following relationship is satisfied: 1.93≤f1_2 / f≤8.

42.

7. The microscope objective lens according to claim 1, characterized in that The object side surface of the third lens is concave at the paraxial position; the curvature radius of the exit side surface of the third lens is R5, the curvature radius of the object side surface is R6, the axial thickness of the third lens is d5, and the following relationship is satisfied: 0.15≤(R5+R6) / (R5-R6)≤1.57; 0.01≤d5 / TTL≤0.03; -4.19≤f3 / f≤-1.

24.

8. The microscope objective lens according to claim 1, characterized in that The exit side surface of the fourth lens is concave at the paraxial position; the curvature radius of the exit side surface of the fourth lens is R7, the curvature radius of the object side surface of the fourth lens is R8, and the axial thickness of the fourth lens is d7, and the following relationship is satisfied: -2.94≤(R7+R8) / (R7-R8)≤-0.12; 0.01≤d7 / TTL≤0.

06.

9. The microscope objective lens according to claim 1, characterized in that The object-side surface of the fifth lens is convex at the paraxial position; the curvature radius of the exit side surface of the fifth lens is R9, the curvature radius of the object-side surface of the fifth lens is R10, and the on-axis thickness of the fifth lens is d9, and the following relationship is satisfied: 0.11≤(R9+R10) / (R9-R10)≤2.20; 0.04≤d9 / TTL≤0.

15.

10. The microscope objective lens according to claim 1, characterized in that The exit side surface of the sixth lens is concave at the paraxial position, and the object side surface of the sixth lens is convex at the paraxial position; the exit side surface of the sixth lens has a curvature radius of R11, the object side surface of the sixth lens has a curvature radius of R12, and the on-axis thickness of the sixth lens is d11, and the following relationship is satisfied: -10.75≤(R11+R12) / (R11-R12)≤-2.17; 0.01≤d11 / TTL≤0.

03.

11. The microscope objective lens according to claim 1, characterized in that The object-side surface of the fourth lens is glued to the exit-side surface of the fifth lens, and the object-side surface of the fifth lens is glued to the exit-side surface of the sixth lens to form a combined lens with negative refractive power. The combined focal length of the fourth lens, the fifth lens, and the sixth lens is f4-5-6, and satisfies the following relationship: -7.70≤f4_5_6 / f≤-1.

41.

12. The microscope objective lens according to claim 1, characterized in that The object-side surface of the seventh lens is convex at the paraxial position; the radius of curvature of the exit side surface of the seventh lens is R13, the radius of curvature of the object-side surface of the seventh lens is R14, the on-axis thickness of the seventh lens is d13, the focal length of the seventh lens is f7, and the following relationship is satisfied: 0.41≤(R13+R14) / (R13-R14)≤2.60; 0.02≤d13 / TTL≤0.09; 2.16≤f7 / f≤7.

34.

13. The microscope objective lens according to claim 1, characterized in that The exit side surface of the eighth lens is convex at the paraxial position, and the object side surface of the eighth lens is convex at the paraxial position; the curvature radius of the exit side surface of the eighth lens is R15, the curvature radius of the object side surface of the eighth lens is R16, and the on-axis thickness of the eighth lens is d15, and the following relationship is satisfied: 0.19≤(R15+R16) / (R15-R16)≤1.15; 0.05≤d15 / TTL≤0.

16.

14. The microscope objective lens according to claim 1, characterized in that The exit side surface of the ninth lens is concave at the paraxial position, and the object side surface of the ninth lens is convex at the paraxial position; the curvature radius of the exit side surface of the ninth lens is R17, the curvature radius of the object side surface of the ninth lens is R18, and the on-axis thickness of the ninth lens is d17, and the following relationship is satisfied: -5.69≤(R17+R18) / (R17-R18)≤-0.82; 0.01≤d17 / TTL≤0.

04.

15. The microscope objective lens according to claim 1, characterized in that The object-side surface of the eighth lens is glued to the exit-side surface of the ninth lens to form a combined lens with positive refractive power. The combined focal length of the eighth lens and the ninth lens is f8-9, and satisfies the following relationship: 4.08≤f8_9 / f≤84.

27.

16. The microscope objective lens according to claim 1, characterized in that The exit side surface of the tenth lens is convex at the paraxial position, and the object side surface of the tenth lens is convex at the paraxial position; the curvature radius of the exit side surface of the tenth lens is R19, the curvature radius of the object side surface of the tenth lens is R20, the on-axis thickness of the tenth lens is d19, and the focal length of the tenth lens is f10, and the following relationship is satisfied: -1.10≤(R19+R20) / (R19-R20)≤0.31; 0.03≤d19 / TTL≤0.11; 2.38≤f10 / f≤12.

26.

17. The microscope objective lens according to claim 1, characterized in that The exit side surface of the eleventh lens is convex at the paraxial position, and the object side surface of the eleventh lens is convex at the paraxial position; the curvature radius of the exit side surface of the eleventh lens is R21, the curvature radius of the object side surface of the eleventh lens is R22, and the on-axis thickness of the eleventh lens is d21, and the following relationship is satisfied: 0.02≤(R21+R22) / (R21-R22)≤1.02; 0.03≤d21 / TTL≤0.

13.

18. The microscope objective lens according to claim 1, characterized in that The exit side surface of the twelfth lens is concave at the paraxial position; the curvature radius of the exit side surface of the twelfth lens is R23, the curvature radius of the object side surface of the twelfth lens is R24, and the axial thickness of the twelfth lens is d23, and the following relationship is satisfied: -2.18≤(R23+R24) / (R23-R24)≤-0.29; 0.01≤d23 / TTL≤0.

04.

19. The microscope objective lens according to claim 1, characterized in that The object-side surface of the eleventh lens is glued to the exit-side surface of the twelfth lens to form a combined lens with negative refractive power. The combined focal length of the eleventh lens and the twelfth lens is f11-12, and satisfies the following relationship: -879.88≤f11_12 / f≤-5.

21.

20. The microscope objective lens according to claim 1, characterized in that The exit side surface of the thirteenth lens is convex at the paraxial position; the curvature radius of the exit side surface of the thirteenth lens is R25, the curvature radius of the object side surface of the thirteenth lens is R26, the on-axis thickness of the thirteenth lens is d25, the focal length of the thirteenth lens is f13, and the following relationship is satisfied: -3.04≤(R25+R26) / (R25-R26)≤-0.53; 0.03≤d25 / TTL≤0.10; 1.68≤f13 / f≤7.

42.

21. The microscope objective lens according to claim 1, characterized in that The exit side surface of the fourteenth lens is convex at the paraxial position, and the object side surface of the fourteenth lens is convex at the paraxial position; the curvature radius of the exit side surface of the fourteenth lens is R27, the curvature radius of the object side surface of the fourteenth lens is R28, and the on-axis thickness of the fourteenth lens is d27, and the following relationship is satisfied: -1.06≤(R27+R28) / (R27-R28)≤-0.27; 0.04≤d27 / TTL≤0.

13.

22. The microscope objective lens according to claim 1, characterized in that The exit side surface of the fifteenth lens is concave at the paraxial position, and the object side surface of the fifteenth lens is concave at the paraxial position; the curvature radius of the exit side surface of the fifteenth lens is R29, the curvature radius of the object side surface of the fifteenth lens is R30, and the on-axis thickness of the fifteenth lens is d29, and the following relationship is satisfied: -0.05≤(R29+R30) / (R29-R30)≤0.98; 0.01≤d29 / TTL≤0.

03.

23. The microscope objective lens according to claim 1, characterized in that The exit side surface of the sixteenth lens is convex at the paraxial position, and the object side surface of the sixteenth lens is convex at the paraxial position; the curvature radius of the exit side surface of the sixteenth lens is R31, the curvature radius of the object side surface of the sixteenth lens is R32, and the on-axis thickness of the sixteenth lens is d31, and the following relationship is satisfied: -1.45≤(R31+R32) / (R31-R32)≤-0.29; 0.02≤d31 / TTL≤0.

09.

24. The microscope objective lens according to claim 1, characterized in that The object-side surface of the fourteenth lens is glued to the exit-side surface of the fifteenth lens, and the object-side surface of the fifteenth lens is glued to the exit-side surface of the sixteenth lens to form a combined lens with positive refractive power.

25. The microscope objective lens according to claim 1, characterized in that The exit side surface of the seventeenth lens is convex at the paraxial position, and the object side surface of the seventeenth lens is convex at the paraxial position; the curvature radius of the exit side surface of the seventeenth lens is R33, the curvature radius of the object side surface of the seventeenth lens is R34, and the on-axis thickness of the seventeenth lens is d33, and the following relationship is satisfied: -1.08≤(R33+R34) / (R33-R34)≤-0.17; 0.02≤d33 / TTL≤0.

08.

26. The microscope objective lens according to claim 1, characterized in that The exit side surface of the eighteenth lens is concave at the paraxial position, and the object side surface of the eighteenth lens is concave at the paraxial position; the exit side surface of the eighteenth lens has a curvature radius of R35, the object side surface of the eighteenth lens has a curvature radius of R36, and the on-axis thickness of the eighteenth lens is d35, and the following relationship is satisfied: 0.25≤(R35+R36) / (R35-R36)≤0.93; 0.01≤d35 / TTL≤0.

04.

27. The microscope objective lens according to claim 1, characterized in that The object-side surface of the seventeenth lens and the exit-side surface of the eighteenth lens are glued to form a combined lens with positive refractive power, and the following relationship is satisfied: 1.30≤f17_18 / f≤81.29.

Images