Microscope objective lens

Abstract

This invention provides an objective lens for a microscope. [Solution] The microscope objective lens is composed of, in order from the output side to the object side, a first lens with positive refractive power, a second lens with negative refractive power, a third lens with negative refractive power, a fourth lens with negative refractive power, a fifth lens with positive refractive power, a sixth lens with positive refractive power, a seventh lens with negative refractive power, an eighth lens with positive or negative refractive power, a ninth lens with positive refractive power, a tenth lens with positive refractive power, an eleventh lens with negative refractive power, a twelfth lens with positive refractive power, a thirteenth lens with negative refractive power, and a fourteenth lens with positive refractive power. The microscope objective lens of the present invention has a compact structure, excellent optical performance and high numerical aperture, and satisfies the design requirements of low distortion, 10x magnification, and long working distance.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of optical technology, and particularly to an objective lens for a microscope applied to devices such as microscopes.

Background Art

[0002] In recent years, the needs for microscope lenses have been increasing. However, due to the constraints of the optical structure, a general microscope lens generates distortion aberration within the field of view of the microscope. In addition, since a microscope lens is composed of a plurality of lenses, its length is inevitably affected. The working distance of a microscope lens with a long structure is also shortened, and the magnification is also affected by the working distance, which is disadvantageous for the operator to use.

[0003] With the development of technology and the increase in diverse needs of users, the requirements for the observation quality of microscope lenses in scientific research have become higher, and there is a strong demand for microscope lenses having excellent optical characteristics, low distortion, high magnification, and long working distance.

Summary of the Invention

Problems to be Solved by the Invention

[0004] An embodiment of the present invention aims to provide an objective lens for a microscope having a high numerical aperture, a compact lens structure, and good optical performance.

Means for Solving the Problems

[0005] To solve the above problems, the present invention provides a microscope objective lens, the microscope objective lens comprising, in order from the output side to the object side, a first lens having positive refractive power, a second lens having negative refractive power, a third lens having negative refractive power, a fourth lens having negative refractive power, a fifth lens having positive refractive power, a sixth lens having positive refractive power, a seventh lens having negative refractive power, an eighth lens having positive or negative refractive power, a ninth lens having positive refractive power, a tenth lens having positive refractive power, an eleventh lens having negative refractive power, a twelfth lens having positive refractive power, a thirteenth lens having negative refractive power, and a fourteenth lens having positive refractive power. The microscope is composed of lenses, and when the focal length of the 9th lens is f9, the combined focal length of the 10th lens and the 11th lens is f10_11, the combined focal length of the 12th lens and the 13th lens is f12_13, the radius of curvature of the exit side of the 14th lens is R27, the radius of curvature of the object side of the 14th lens is R28, the focal length of the microscope objective lens is f, the on-axial distance from the object plane of the microscope objective lens to the object side of the 14th lens is WD, the on-axial distance from the object plane of the microscope objective lens to the exit plane of the 1st lens is TTL, and the numerical aperture of the microscope objective lens is NA, the following conditions (1) to (5) are satisfied. 1.60 ≤ f9 / f ≤ 4.00 (1) -3.00≦f10_11 / f12_13≦-1.40 (2) -9.00≦(R27+R28) / (R27-R28)≦-1.60 (3) 0.05 ≤ WD / TTL ≤ 0.13 (4) 2.40 ≤ WD * NA ≤ 5.50 (5)

[0006] Preferably, the object side of the fourth lens and the output side of the fifth lens are joined to form a first cemented lens, the object side of the seventh lens and the output side of the eighth lens are joined to form a second cemented lens, the object side of the tenth lens and the output side of the eleventh lens are joined to form a third cemented lens, and the object side of the twelfth lens and the output side of the thirteenth lens are joined to form a fourth cemented lens, wherein the difference in Abbe numbers of the two lenses in any one of the cemented lenses is Δv and the following condition (6) is satisfied. Δv≧35.00 (6)

[0007] Preferably, the first lens has a convex surface paraxially on its exit side and a convex surface paraxially on its object side, and satisfies the following conditions (7) to (9) when R1 is the radius of curvature of the exit side of the first lens, R2 is the radius of curvature of the object side of the first lens, f1 is the focal length of the first lens, and d1 is the on-axial thickness of the first lens. -1.57≦(R1+R2) / (R1-R2)≦0.00 (7) 0.67 ≤ f1 / f ≤ 3.23 (8) 0.01 ≤ d1 / TTL ≤ 0.07 (9)

[0008] Preferably, the second lens has a concave surface paraxially on its exit side and a concave surface paraxially on its object side, and satisfies the following conditions (10) to (12) when the radius of curvature of the exit side of the second lens is R3, the radius of curvature of the object side of the second lens is R4, the focal length of the second lens is f2, and the on-axial thickness of the second lens is d3. 0.22≦(R3+R4) / (R3-R4)≦1.38 (10) -2.41≦f² / f≦-0.71 (11) 0.01 ≤ d3 / TTL ≤ 0.02 (12)

[0009] Preferably, the third lens has a concave surface paraxially on its exit side and a convex surface paraxially on its object side, and satisfies the following conditions (13) to (15) when the radius of curvature of the exit side of the third lens is R5, the radius of curvature of the object side of the third lens is R6, the focal length of the third lens is f3, and the on-axial thickness of the third lens is d5. -7.51≦(R5+R6) / (R5-R6)≦-1.63 (13) -4.33 ≤ f3 / f ≤ -1.18 (14) 0.01 ≤ d5 / TTL ≤ 0.08 (15)

[0010] Preferably, the fourth lens has a concave surface paraxially on its exit side and a convex surface paraxially on its object side, and satisfies the following conditions (16) to (18) when the radius of curvature of the exit side of the fourth lens is R7, the radius of curvature of the object side of the fourth lens is R8, the focal length of the fourth lens is f4, and the on-axial thickness of the fourth lens is d7. 0.61≦(R7+R8) / (R7-R8)≦2.26 (16) -5.94 ≤ f₄ / f ≤ -1.57 (17) 0.04 ≤ d7 / TTL ≤ 0.16 (18)

[0011] Preferably, the fifth lens has a concave surface paraxially on its exit side and a convex surface paraxially on its object side, and satisfies the following conditions (19) to (21) when the radius of curvature of the exit side of the fifth lens is R9, the radius of curvature of the object side of the fifth lens is R10, the focal length of the fifth lens is f5, and the on-axial thickness of the fifth lens is d9. -9.50≦(R9+R10) / (R9-R10)≦-2.61(19) 1.09 ≤ f5 / f ≤ 3.49 (20) 0.01 ≤ d9 / TTL ≤ 0.06 (21)

[0012] Preferably, the object side of the fourth lens and the output side of the fifth lens are joined to form a cemented lens having a positive refractive power, and when the combined focal length of the fourth lens and the fifth lens is f4_5, the following condition (22) is satisfied. 1.35 ≤ f₄₅ / f ≤ 4.75 (22)

[0013] Preferably, the sixth lens has a convex surface in the paraxial direction on its exit side and a convex surface in the paraxial direction on its object side, and satisfies the following conditions (23) to (25) when the radius of curvature of the exit side of the sixth lens is R11, the radius of curvature of the object side of the sixth lens is R12, the focal length of the sixth lens is f6, and the on-axial thickness of the sixth lens is d11. 0.18≦(R11+R12) / (R11-R12)≦1.26 (23) 0.98 ≤ f6 / f ≤ 3.59 (24) 0.02 ≤ d11 / TTL ≤ 0.14 (25)

[0014] Preferably, the seventh lens has a convex surface paraxially on its exit side and a concave surface paraxially on its object side, and satisfies the following conditions (26) to (28) when the radius of curvature of the exit side of the seventh lens is R13, the radius of curvature of the object side of the seventh lens is R14, the focal length of the seventh lens is f7, and the on-axial thickness of the seventh lens is d13. -0.43≦(R13+R14) / (R13-R14)≦0.25 (26) -4.27≦f7 / f≦-1.15 (27) 0.01 ≤ d13 / TTL ≤ 0.04 (28)

[0015] Preferably, the eighth lens has a concave surface in the paraxial direction on its exit side, and satisfies the following conditions (29) to (31) when the radius of curvature of the exit side of the eighth lens is R15, the radius of curvature of the object side of the eighth lens is R16, the focal length of the eighth lens is f8, and the on-axial thickness of the eighth lens is d15. -3.39≦(R15+R16) / (R15-R16)≦0.11 (29) -7.32 ≦ f8 / f ≦ 20.86 (30) 0.03 ≦ d15 / TTL ≦ 0.17 (31)

[0016] Preferably, the object side surface of the seventh lens and the exit side surface of the eighth lens are joined to form a cemented lens having a negative refractive power. When the combined focal length of the seventh lens and the eighth lens is f7_8, the following conditional expression (32) is satisfied. -9.03 ≦ f7_8 / f ≦ -0.95 (32)

[0017] Preferably, the exit side surface of the ninth lens is concave paraxially, and the object side surface is convex paraxially. When 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, and the on-axis thickness of the ninth lens is d17, the following conditional expressions (33) to (34) are satisfied. -0.06 ≦ (R17 + R18) / (R17 - R18) ≦ 0.60 (33) 0.03 ≦ d17 / TTL ≦ 0.17 (34)

[0018] Preferably, the exit side surface of the tenth lens is concave paraxially, and the object side surface is concave paraxially. When the radius of curvature of the exit side surface of the tenth lens is R19, the radius of curvature of the object side surface of the tenth lens is R20, the focal length of the tenth lens is f10, and the on-axis thickness of the tenth lens is d19, the following conditional expressions (35) to (37) are satisfied. 2.10 ≦ (R19 + R20) / (R19 - R20) ≦ 8.39 (35) 1.83 ≦ f10 / f ≦ 7.29 (36) 0.01 ≦ d19 / TTL ≦ 0.02 (37)

[0019] Preferably, the 11th lens has a concave surface paraxially on its exit side and a convex surface paraxially on its object side, and satisfies the following conditions (38) to (40) when the radius of curvature of the exit side of the 11th lens is R21, the radius of curvature of the object side of the 11th lens is R22, the focal length of the 11th lens is f11, and the on-axial thickness of the 11th lens is d21. -1.80≦(R21+R22) / (R21-R22)≦-0.38 (38) -13.59 ≤ f11 / f ≤ -1.56 (39) 0.05 ≤ d21 / TTL ≤ 0.19 (40)

[0020] Preferably, the object side of the 10th lens and the output side of the 11th lens are joined to form a cemented lens having a positive refractive power, satisfying the following condition (41). 1.25 ≤ f₁₀₁₁ / f ≤ 6.42 (41)

[0021] Preferably, the 12th lens has a concave surface in the paraxial direction on its exit side, and satisfies the following conditions (42) to (44) when the radius of curvature of the exit side of the 12th lens is R23, the radius of curvature of the object side of the 12th lens is R24, the focal length of the 12th lens is f12, and the on-axial thickness of the 12th lens is d23. -4.79≦(R23+R24) / (R23-R24)≦-0.41 (42) 0.49 ≤ f12 / f ≤ 2.89 (43) 0.02 ≤ d23 / TTL ≤ 0.08 (44)

[0022] Preferably, the 13th lens has a concave surface paraxially on the side surface of the object, and satisfies the following conditions (45) to (47) when the radius of curvature of the exit side surface of the 13th lens is R25, the radius of curvature of the object side surface of the 13th lens is R26, the focal length of the 13th lens is f13, and the on-axial thickness of the 13th lens is d25. 0.36≦(R25+R26) / (R25-R26)≦2.47 (45) -1.62 ≤ f13 / f ≤ -0.33 (46) 0.01 ≤ d25 / TTL ≤ 0.09 (47)

[0023] Preferably, the object side of the 12th lens and the output side of the 13th lens are joined to form a cemented lens having a negative refractive power, and the following condition (48) is satisfied. -4.11≦f12_13 / f≦-0.97 (48)

[0024] Preferably, the 14th lens has a concave surface paraxially on its exit side and a concave surface paraxially on its object side, and satisfies the following conditions (49) to (50) when the focal length of the 14th lens is f14 and the on-axial thickness of the 14th lens is d27. 0.71 ≤ f14 / f ≤ 3.74 (49) 0.01 ≤ d27 / TTL ≤ 0.15 (50) [Effects of the Invention]

[0025] The beneficial effects of the present invention are as follows: The above lens arrangement allows control of the flow of light rays between the lenses, contributes to smooth propagation after the light rays enter the lens group, makes the lens structure compact, controls the overall length of the lenses so that the imaging range reaches a desired state, allows the microscope objective lens to have a high numerical aperture, ensures that the light rays have sufficient focusing ability, and has excellent optical performance, satisfying the design requirements of low distortion, 10x magnification, and long working distance.

[0026] One or more embodiments are illustrated by the corresponding drawings, and these illustrative descriptions do not constitute limitations to embodiments. Components having the same reference numerals in the drawings are shown as analogous components, and unless otherwise specified, the drawings do not constitute proportional limitations. [Brief explanation of the drawing]

[0027] [Figure 1] This is a schematic diagram showing the structure of a microscope objective lens according to the first embodiment of the present invention. [Figure 2] Figure 1 is a schematic diagram illustrating the field curvature and distortion of a microscope objective lens. [Figure 3] Figure 1 is a schematic diagram showing the chromatic aberration of magnification in a microscope objective lens. [Figure 4] Figure 1 is a schematic diagram showing the axial chromatic aberration of a microscope objective lens. [Figure 5] This is a schematic diagram showing the structure of a microscope objective lens according to a second embodiment of the present invention. [Figure 6] Figure 5 is a schematic diagram illustrating the field curvature and distortion of a microscope objective lens. [Figure 7] Figure 5 is a schematic diagram illustrating the chromatic aberration of a microscope objective lens. [Figure 8] Figure 5 is a schematic diagram showing the axial chromatic aberration of a microscope objective lens. [Figure 9] This is a schematic diagram showing the structure of a microscope objective lens according to a third embodiment of the present invention. [Figure 10] Figure 9 is a schematic diagram illustrating the field curvature and distortion of a microscope objective lens. [Figure 11] Figure 9 is a schematic diagram showing the chromatic aberration of magnification in a microscope objective lens. [Figure 12] Figure 9 is a schematic diagram showing the axial chromatic aberration of a microscope objective lens. [Figure 13] This is a schematic diagram showing the structure of a microscope objective lens according to the fourth embodiment of the present invention. [Figure 14] Figure 13 is a schematic diagram illustrating the field curvature and distortion of a microscope objective lens. [Figure 15] Figure 13 is a schematic diagram showing the chromatic aberration of magnification in a microscope objective lens. [Figure 16] Figure 13 is a schematic diagram showing the axial chromatic aberration of a microscope objective lens. [Modes for carrying out the invention]

[0028] To clarify the objectives, solutions, and merits of the embodiments of the present invention, each embodiment of the present invention will be described in detail below with reference to the drawings. However, it will be apparent to those skilled in the art that many technical details are described in each embodiment of the present invention in order to better understand the present application. However, the technical proposal for which the present application is claimed can also be realized without these technical details and the various changes and modifications based on the embodiments below.

[0029] In embodiments of the present invention, terms such as "up," "down," "left," "right," "front," "back," "top," "bottom," "inside," "outside," "center," "vertical," "horizontal," "lateral," and "vertical" refer to directions or positional relationships as shown in the drawings. These terms are primarily for the purpose of better describing the present invention and its embodiments, and are not intended to limit the indicated device, element, or component to necessarily having a specific direction or being structured and operated in a specific direction.

[0030] Furthermore, some of the above terms may be used to express meanings other than those related to direction or position. For example, the term "above" may, in some cases, be used to express a dependency or connection relationship. Those skilled in the art will be able to understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] Furthermore, the terms "attachment," "installation," "provided," "opening," "connection," and "connection" should be understood in a broad sense. For example, it may be a fixed connection, a removable connection, an integral structure, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, or an internal communication between two devices, elements, or components. Those skilled in the art will be able to understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0032] Furthermore, terms such as "first," "second," etc., are primarily used to distinguish between different devices, elements, or components (the specific types and structures may be the same or different), and are not intended to explicitly or implicitly indicate the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise specified, "plural" means two or more.

[0033] Referring to Figure 1, the present invention provides microscope objective lenses 10, 20, 30, and 40, which, in order from the output side to the object side, consist of a first lens L1 having positive refractive power, a second lens L2 having negative refractive power, a third lens L3 having negative refractive power, a fourth lens L4 having negative refractive power, a fifth lens L5 having positive refractive power, and a third lens L2 having negative refractive power. It is composed of a sixth lens L6, a seventh lens L7 having negative refractive power, an eighth lens L8 having positive or negative refractive power, a ninth lens L9 having positive refractive power, a tenth lens L10 having positive refractive power, an eleventh lens L11 having negative refractive power, a twelfth lens L12 having positive refractive power, a thirteenth lens L13 having negative refractive power, and a fourteenth lens L14 having positive refractive power.

[0034] The focal length of the ninth lens L9 is f9, the combined focal length of the tenth lens L10 and the eleventh lens L11 is f10_11, the combined focal length of the twelfth lens L12 and the thirteenth lens L13 is f12_13, the radius of curvature of the exit side of the fourteenth lens L14 is R27, the radius of curvature of the object side of the fourteenth lens L14 is R28, the focal lengths of the microscope objective lenses 10, 20, 30, and 40 are f, and the microscope When the axial distance from the object surface of the objective lenses 10, 20, 30, and 40 to the object side surface of the 14th lens L14 is WD, i.e., the working distance is WD, the axial distance from the object surface of the microscope objective lenses 10, 20, 30, and 40 to the output side surface of the first lens L1 is TTL, i.e., the optical length is TTL, and the numerical aperture of the microscope objective lenses 10, 20, 30, and 40 is NA, the following conditions (1) to (5) are satisfied. 1.60 ≤ f9 / f ≤ 4.00 (1) -3.00≦f10_11 / f12_13≦-1.40 (2) -9.00≦(R27+R28) / (R27-R28)≦-1.60 (3) 0.05 ≤ WD / TTL ≤ 0.13 (4) 2.40 ≤ WD * NA ≤ 5.50 (5)

[0035] Here, conditional equation (1) defines the range of the ratio between the focal length f9 of the ninth lens L9 and the focal lengths f of the microscope objective lenses 10, 20, 30, and 40. Within the range limited by the conditional equation, it is possible to ensure that the light rays have sufficient focusing ability and contribute to the smooth propagation of the light rays.

[0036] Conditional equation (2) defines a range for the ratio of the combined focal length f10_11 of the cemented lens formed by the 10th lens L10 and the 11th lens L11 to the combined focal length f12_13 formed by the 12th lens L12 and the 13th lens L13. Within this defined range, it is advantageous to control the flow of light rays between adjacent cemented lens groups and to make the lens structure compact.

[0037] Conditional equation (3) defines the shape of the 14th lens L14, which is the lens closest to the object being measured, and by controlling its shape, it contributes to the smooth propagation of light rays after they enter the microscope objective lenses 10, 20, 30, and 40.

[0038] Conditional equation (4) defines the range of the ratio between the working distance WD and the optical length TTL of the microscope objective lenses 10, 20, 30, and 40. If the ratio falls below the lower limit of conditional equation (4), the distance between the microscope objective lenses 10, 20, 30, and 40 and the object being measured becomes too narrow, resulting in poor operability. Conversely, if the ratio exceeds the upper limit, the space occupied by the lens portion of the microscope objective lenses 10, 20, 30, and 40 becomes insufficient, limiting the thickness of the lenses that can be placed and the optical path, making it difficult to correct spherical aberration and chromatic aberration. Therefore, within this range, the working distance WD and optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be effectively balanced, improving the operability of the microscope objective lenses 10, 20, 30, and 40, which is advantageous for the arrangement of lenses and optical paths, and further improving the correction of spherical aberration and chromatic aberration.

[0039] Conditional equation (5) defines the range of the product of the working distance WD and numerical aperture NA of the microscope objective lenses 10, 20, 30, and 40. By limiting its upper limit, it is possible to avoid the working distance WD of the microscope objective lenses 10, 20, 30, and 40 being too long relative to the numerical aperture NA, thereby achieving satisfactory aberration performance and high resolution. Furthermore, by limiting the lower limit of the above product, it is possible to avoid the working distance WD becoming too short, eliminating the need for the user to take care to prevent collision between the objective lens and the object being measured, thereby improving work efficiency during measurement. In particular, when observing with microscope objective lenses, it is often necessary to observe objects with extremely large uneven surfaces using low numerical aperture objective lenses. However, in this invention, by defining the lower limit of WD*NA, it is possible to ensure that low numerical aperture objective lenses have a sufficiently long working distance. As a result, even objects with large surface irregularities can be measured, thus achieving high versatility of microscope objective lenses. In other words, within the range defined by condition (5), sufficient resolution, high work efficiency, and high versatility can be ensured for the microscope objective lenses 10, 20, 30, and 40.

[0040] In this proposed technology, the above setup allows for control of the flow of light rays between lenses, contributing to smooth propagation after the light rays enter the lens group, making the lens structure compact, controlling the overall length of the lenses so that the imaging range reaches a desired state, enabling the microscope objective lens to have a high numerical aperture, ensuring that the light rays have sufficient focusing ability, and providing excellent optical performance, satisfying the design requirements of low distortion, 10x magnification, and long working distance.

[0041] The units for the focal length, thickness, image height, and optical length mentioned above are millimeters.

[0042] Preferably, the object side of the fourth lens L4 and the output side of the fifth lens L5 are joined to form a first cemented lens, the object side of the seventh lens L7 and the output side of the eighth lens L8 are joined to form a second cemented lens, the object side of the tenth lens L10 and the output side of the eleventh lens L11 are joined to form a third cemented lens, and the object side of the twelfth lens L12 and the output side of the thirteenth lens L13 are joined to form a fourth cemented lens, wherein the difference in Abbe numbers of the two lenses in any one of the cemented lenses is Δv and the following condition (6) is satisfied. Δv≧35.00 (6)

[0043] Condition (6) defines the range of the difference in Abbe numbers between the two lenses in any one cemented lens, and within this range, the chromatic aberration of the system can be effectively corrected so that chromatic aberration |LC| ≤ 0.4 micrometers.

[0044] In this proposed technology, the first lens L1 has a convex surface paraxially on its exit side and a convex surface paraxially on its object side. In other selectable technologies, the object side and exit side of the first lens L1 may be configured with other concave-convex distributions.

[0045] When R1 is the radius of curvature of the exit side surface of the first lens L1, R2 is the radius of curvature of the object side surface of the first lens L1, f1 is the focal length of the first lens L1, and d1 is the on-axial thickness of the first lens L1, the following conditions (7) to (9) are satisfied. -1.57≦(R1+R2) / (R1-R2)≦0.00 (7) 0.67 ≤ f1 / f ≤ 3.23 (8) 0.01 ≤ d1 / TTL ≤ 0.07 (9)

[0046] Condition (7) defines the shape of the first lens L1 so that the first lens L1 can effectively correct the spherical aberration of the system, and more preferably satisfies the condition -0.98 ≤ (R1 + R2) / (R1 - R2) ≤ 0.00. Condition (8) defines the range of the ratio between the focal length f1 of the first lens L1 and the focal length f of the microscope objective lenses 10, 20, 30, and 40, within which the optical performance of the microscope objective lenses 10, 20, 30, and 40 can be improved, and more preferably satisfies the condition 1.08 ≤ f1 / f ≤ 2.59. Conditional equation (9) defines a range for the ratio of the axial thickness d1 of the first lens L1 to the optical length TTL of the microscope objective lenses 10, 20, 30, and 40, and contributes to rationally controlling the optical lengths of the microscope objective lenses 10, 20, 30, and 40 within that range, and more preferably satisfies the conditional equation 0.02 ≤ d1 / TTL ≤ 0.06.

[0047] In the present invention, the second lens has a paraxially concave exit side and a paraxially concave object side. In other selectable technical solutions, the object side and exit side of the second lens L1 may be configured with other concave / convex distributions.

[0048] Preferably, when the radius of curvature of the exit side surface of the second lens L2 is R3, the radius of curvature of the object side surface of the second lens L2 is R4, the focal length of the second lens L2 is f2, and the on-axial thickness of the second lens L2 is d3, the following conditions (10) to (12) are satisfied. 0.22≦(R3+R4) / (R3-R4)≦1.38 (10) -2.41≦f² / f≦-0.71 (11) 0.01 ≤ d3 / TTL ≤ 0.02 (12)

[0049] Conditional equation (10) defines the shape of the second lens, and within the range defined by conditional equation (10), the shape of the second lens L2 can be rationally controlled, the degree of deflection after the light ray passes through the second lens L2 can be mitigated, and aberrations can be effectively reduced, more preferably satisfying conditional equation 0.36 ≤ (R3 + R4) / (R3 - R4) ≤ 1.11. Conditional equation (11) defines the ratio of the focal length f2 of the second lens L2 to the focal length f of the microscope objective lenses 10, 20, 30, and 40, and within the above range, contributes to the reduction of aberrations and improvement of image quality, more preferably satisfying conditional equation -1.51 ≤ f2 / f ≤ -0.89. Conditional equation (12) defines the range of the ratio between the axial thickness d3 of the second lens L2 and the optical length TTL of the microscope objective lenses 10, 20, 30, and 40, and contributes to rationally controlling the optical lengths of the microscope objective lenses 10, 20, 30, and 40.

[0050] In this proposed technology, the third lens has a concave surface paraxially on its exit side and a convex surface paraxially on its object side. In other selectable technologies, the object side and exit side of the third lens L3 may be configured with other concave / convex distributions.

[0051] Preferably, when 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 of the third lens L3 is R6, the focal length of the third lens L3 is f3, and the on-axial thickness of the third lens L3 is d5, the following conditions (13) to (15) are satisfied. -7.51≦(R5+R6) / (R5-R6)≦-1.63 (13) -4.33 ≤ f3 / f ≤ -1.18 (14) 0.01 ≤ d5 / TTL ≤ 0.08 (15)

[0052] Conditional equation (13) defines the shape of the third lens L3 and, within the range defined by conditional equation (13), is advantageous for correcting problems such as off-axis angle of view aberrations, and more preferably satisfies the conditional equation -4.70 ≤ (R5 + R6) / (R5 - R6) ≤ -2.04. Conditional equation (14) defines 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, and, within this range, contributes to improving the performance of the optical system, and more preferably satisfies the conditional equation -2.70 ≤ f3 / f ≤ -1.47. Conditional equation (15) defines the on-axial thickness d5 of the third lens L3 and is advantageous for rationally controlling the optical lengths of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the conditional equation 0.02 ≤ d5 / TTL ≤ 0.06.

[0053] In this proposed technology, the fourth lens L4 has a concave surface paraxially on its exit side and a convex surface paraxially on its object side. In other selectable technologies, the object side and exit side of the fourth lens L4 may be configured with other concave / convex distributions.

[0054] Preferably, when 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 focal length of the fourth lens L4 is f4, and the on-axial thickness of the fourth lens L4 is d7, the following conditions (16) to (18) are satisfied. 0.61≦(R7+R8) / (R7-R8)≦2.26 (16) -5.94 ≤ f₄ / f ≤ -1.57 (17) 0.04 ≤ d7 / TTL ≤ 0.16 (18)

[0055] Conditional equation (16) defines the shape of the fourth lens L4 and contributes to reducing aberrations of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the conditional equation 0.97 ≤ (R7 + R8) / (R7 - R8) ≤ 1.81. Conditional equation (17) defines the ratio of the focal length f4 of the fourth lens L4 to the focal length f of the microscope objective lenses 10, 20, 30, and 40, and within this range, contributes to reducing aberrations and improving image quality, and more preferably satisfies the conditional equation -3.71 ≤ f4 / f ≤ -1.96. Conditional equation (18) defines a range for the ratio of the on-axial thickness d7 of the fourth lens L4 to the optical length TTL of the microscope objective lenses 10, 20, 30, and 40, and within this range is advantageous for rationally controlling the optical lengths of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the conditional equation 0.06 ≤ d7 / TTL ≤ 0.13.

[0056] In this proposed technology, the fifth lens L5 has a concave surface paraxially on its exit side and a convex surface paraxially on its object side. In other selectable technologies, the object side and exit side of the fifth lens L5 may be configured with other concave / convex distributions.

[0057] Preferably, when 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 focal length of the fifth lens L5 is f5, and the on-axial thickness of the fifth lens L5 is d9, the following conditions (19) to (21) are satisfied. -9.50≦(R9+R10) / (R9-R10)≦-2.61 (19) 1.09 ≤ f5 / f ≤ 3.49 (20) 0.01 ≤ d9 / TTL ≤ 0.06 (21)

[0058] Conditional equation (19) defines the shape of the fifth lens L5 so that the fifth lens L5 can effectively correct the spherical aberration of the system, and more preferably satisfies the conditional equation -5.94 ≤ (R9 + R10) / (R9 - R10) ≤ -3.27. Conditional equation (20) defines the ratio of the focal length f5 of the fifth lens L5 to the focal length f of the microscope objective lenses 10, 20, 30, and 40, and within this range contributes to the reduction of aberrations and the improvement of image quality, and more preferably satisfies the conditional equation 1.75 ≤ f5 / f ≤ 2.79. Conditional equation (21) defines a range of values ​​for the ratio of the axial thickness d9 of the fifth lens L5 to the optical length TTL of the microscope objective lenses 10, 20, 30, and 40, and is advantageous for rationally controlling the optical lengths of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the conditional equation 0.01 ≤ d9 / TTL ≤ 0.05.

[0059] In this proposed technology, the output side of the fourth lens L4 and the object side of the fifth lens L5 are joined to form a cemented lens having a positive refractive power, and when the combined focal length of the fourth lens L4 and the fifth lens L5 is f4_5, the following condition (22) is satisfied. 1.35 ≤ f₄₅ / f ≤ 4.75 (22)

[0060] Within the range of the conditional expression, it contributes to reducing aberrations and improving image quality, and more preferably satisfies the conditional expression 2.16 ≤ f4_5 / f ≤ 3.80.

[0061] In this proposed technology, the sixth lens L6 has a convex surface paraxially on its exit side and a convex surface paraxially on its object side. In other selectable technologies, the object side and exit side of the sixth lens L6 may be configured with other concave-convex distributions.

[0062] Preferably, when 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, the focal length of the sixth lens L6 is f6, and the on-axial thickness of the sixth lens L6 is d11, the following conditions (23) to (25) are satisfied. 0.18≦(R11+R12) / (R11-R12)≦1.26 (23) 0.98 ≤ f6 / f ≤ 3.59 (24) 0.02 ≤ d11 / TTL ≤ 0.14 (25)

[0063] Conditional equation (23) defines the shape of the sixth lens L6, and within that range, it contributes to reducing spherical aberration and improving image quality of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the conditional equation 0.29 ≤ (R11 + R12) / (R11 - R12) ≤ 1.01. Conditional equation (24) defines the ratio of the focal length f6 of the sixth lens L6 to the focal length f of the microscope objective lenses 10, 20, 30, and 40, and within the above range, it contributes to reducing aberration and improving image quality, and more preferably satisfies the conditional equation 1.58 ≤ f6 / f ≤ 2.87. Conditional equation (25) defines the range of the ratio between the axial thickness d11 of the sixth lens L6 and the optical length TTL of the microscope objective lenses 10, 20, 30, and 40. Within the range defined by conditional equation (25), it is advantageous to rationally control the optical lengths of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the conditional equation 0.03 ≤ d11 / TTL ≤ 0.11.

[0064] In this proposed technology, the seventh lens L7 has a convex surface paraxially on its exit side and a concave surface paraxially on its object side. In other selectable technologies, the object side and exit side of the seventh lens L7 may be configured with other concave / convex distributions.

[0065] Preferably, when the radius of curvature of the object side surface of the seventh lens L7 is R13, the radius of curvature of the exit side surface of the seventh lens L7 is R14, the focal length of the seventh lens L7 is f7, and the on-axial thickness of the seventh lens L7 is d13, the following conditions (26) to (28) are satisfied. -0.43≦(R13+R14) / (R13-R14)≦0.25 (26) -4.27≦f7 / f≦-1.15 (27) 0.01 ≤ d13 / TTL ≤ 0.04 (28)

[0066] Condition (26) defines the shape of the seventh lens L7, and rationally controlling the shape of the seventh lens L7 is advantageous in mitigating the degree of deflection when light rays pass through the microscope objective lenses 10, 20, 30, and 40, causing the system to have excellent image quality and low sensitivity, and more preferably satisfies the condition -0.27 ≤ (R13 + R14) / (R13 - R14) ≤ 0.20. Condition (27) defines the range of the ratio between the focal length f7 of the seventh lens L7 and the focal lengths f of the microscope objective lenses 10, 20, 30, and 40, within which the seventh lens L7 has appropriate negative refractive power, is advantageous in reducing system aberrations, and more preferably satisfies the condition -2.67 ≤ f7 / f ≤ -1.44. Condition (28) defines the on-axial thickness d13 of the seventh lens L7 and is advantageous for rationally controlling the optical lengths of the microscope objective lenses 10, 20, 30, and 40 within the range defined by condition (28), and more preferably satisfies the condition 0.01 ≤ d13 / TTL ≤ 0.03.

[0067] In this proposed technology, the eighth lens L8 has a concave surface paraxially on its exit side and a convex or concave surface paraxially on its object side. In other selectable technologies, the exit surface of the eighth lens L8 may be set to be convex.

[0068] Preferably, when 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, the focal length of the eighth lens L8 is f8, and the on-axial thickness of the eighth lens L8 is d15, the following conditions (29) to (31) are satisfied. -3.39≦(R15+R16) / (R15-R16)≦0.11 (29) -7.32 ≤ f8 / f ≤ 20.86 (30) 0.03 ≤ d15 / TTL ≤ 0.17 (31)

[0069] Conditional equation (29) defines the shape of the eighth lens L8, and within this range, as the thinning of the microscope objective lenses 10, 20, 30, and 40 progresses, it is advantageous for correcting the problem of axial chromatic aberration, and more preferably satisfies the conditional equation -2.12 ≤ (R15 + R16) / (R15 - R16) ≤ 0.09. Conditional equation (30) defines the ratio of the focal length f8 of the eighth lens L8 to the focal length f of the microscope objective lenses 10, 20, 30, and 40, and within this range, it contributes to improving the optical performance of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the conditional equation -4.58 ≤ f8 / f ≤ 16.69. Condition (31) defines the on-axial thickness d15 of the eighth lens L8 and is advantageous for rationally controlling the optical lengths of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the condition 0.06 ≤ d15 / TTL ≤ 0.14.

[0070] In this proposed technology, the object side of the seventh lens L7 and the output side of the eighth lens L8 are joined to form a cemented lens having negative refractive power, and when the combined focal length of the seventh lens L7 and the eighth lens L8 is f7_8, the following condition (32) is satisfied. -9.03 ≤ f7_8 / f ≤ -0.95 (32)

[0071] Conditional equation (32) defines a range for the ratio between the combined focal length f7_8 of the cemented lens formed by the seventh lens L7 and the eighth lens L8 and the focal length f of the microscope objective lenses 10, 20, 30, and 40. Within this range, the optical performance of the microscope objective lenses 10, 20, 30, and 40 can be improved, and more preferably, the condition -5.64 ≤ f7_8 / f ≤ -1.19 is satisfied.

[0072] In this proposed technology, the ninth lens L9 has a concave surface paraxially on its exit side and a convex surface paraxially on its object side. In other selectable technologies, the object side and exit side of the ninth lens L9 may be configured with other concave / convex distributions.

[0073] Preferably, when the exit side surface of the ninth lens L9 has a radius of curvature R17, the radius of curvature of the object side surface of the ninth lens L9 is R18, and the on-axial thickness of the ninth lens L9 is d17, the following conditions (33) to (34) are satisfied. -0.06≦(R17+R18) / (R17-R18)≦0.60 (33) 0.03 ≤ d17 / TTL ≤ 0.17 (34)

[0074] Conditional equation (33) defines the shape of the ninth lens L9, and within the range of the conditional equation, the ninth lens L9 can effectively correct the spherical aberration of the system and contribute to improving the image quality, and more preferably satisfies the conditional equation -0.03 ≤ (R17 + R18) / (R17 - R18) ≤ 0.48. Conditional equation (34) defines the on-axial thickness d17 of the ninth lens L9, and within the range, contributes to rationally controlling the optical length TTL of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the conditional equation 0.05 ≤ d17 / TTL ≤ 0.13.

[0075] In this proposed technology, the tenth lens L10 has a concave surface paraxially on its exit side and a concave surface paraxially on its object side. In other selectable technologies, the object side and exit side of the tenth lens L10 may be configured with other concave / convex distributions.

[0076] Preferably, when the radius of curvature of the exit side surface of the 10th lens L10 is R19, the radius of curvature of the object side surface of the 10th lens L10 is R20, the focal length of the 10th lens L10 is f10, and the on-axial thickness of the 10th lens L10 is d19, the following conditions (35) to (37) are satisfied. 2.10≦(R19+R20) / (R19-R20)≦8.39 (35) 1.83 ≤ f10 / f ≤ 7.29 (36) 0.01 ≤ d19 / TTL ≤ 0.02 (37)

[0077] Conditional equation (35) defines the shape of the 10th lens L10, and within the range defined by the conditional equation, the degree of deflection of light rays passing through the 10th lens L10 can be mitigated and aberrations can be effectively reduced, more preferably satisfying conditional equation 3.36 ≤ (R19 + R20) / (R19 - R20) ≤ 6.71. Conditional equation (36) defines the ratio of the focal length f10 of the 10th lens L10 to the focal length f of the microscope objective lenses 10, 20, 30, and 40, and within the above range, it is advantageous for improving the optical performance and image quality of the microscope objective lenses 10, 20, 30, and 40, more preferably satisfying conditional equation 2.92 ≤ f10 / f ≤ 5.83. Conditional equation (37) defines the axial thickness d19 of the 10th lens L10 and contributes to rationally controlling the optical lengths of the microscope objective lenses 10, 20, 30, and 40 within that range.

[0078] In this proposed technology, the 11th lens L11 has a concave surface paraxially on its exit side and a convex surface paraxially on its object side. In other selectable technologies, the object side and exit side of the 11th lens L11 may be configured with other concave / convex distributions.

[0079] Preferably, when the radius of curvature of the exit side surface of the 11th lens L11 is R21, the radius of curvature of the object side surface of the 11th lens L11 is R22, the focal length of the 11th lens L11 is f11, and the on-axial thickness of the 11th lens L11 is d21, the following conditions (38) to (40) are satisfied. -1.80≦(R21+R22) / (R21-R22)≦-0.38 (38) -13.59 ≤ f11 / f ≤ -1.56 (39) 0.05 ≤ d21 / TTL ≤ 0.19 (40)

[0080] Conditional equation (38) defines the shape of the 11th lens L11, and within the range defined by this conditional equation, it is advantageous for improving the optical performance of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the conditional equation -1.13 ≤ (R21 + R22) / (R21 - R22) ≤ -0.47. Conditional equation (39) defines the ratio of the focal length f11 of the 11th lens L11 to the focal length f of the microscope objective lenses 10, 20, 30, and 40, and within the above range, the 11th lens L11 has an appropriate negative refractive power, which is advantageous for reducing system aberrations, and more preferably satisfies the conditional equation -8.49 ≤ f11 / f ≤ -1.95. Conditional equation (40) defines the ratio of the thickness d21 of the 11th lens L11 to the optical length TTL of the microscope objective lenses 10, 20, 30, and 40. Within the range defined by the conditional equation, it is advantageous to rationally control the optical lengths of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the conditional equation 0.08 ≤ d21 / TTL ≤ 0.15.

[0081] In this proposed technology, the object side surface of the 10th lens L10 and the output side surface of the 11th lens L11 are joined to form a cemented lens having a positive refractive power, and the following condition (41) is satisfied. 1.25 ≤ f₁₀₁₁ / f ≤ 6.42 (41)

[0082] Within the range defined by condition (41), the optical performance of the microscope objective lenses 10, 20, 30, and 40 can be improved, and more preferably, the condition 2.00 ≤ f10_11 / f ≤ 5.13 is satisfied.

[0083] In this proposed technology, the 12th lens L12 has a concave surface paraxially on its exit side, and an object side that is concave or convex paraxially. In other feasible technologies, the exit surface of the 12th lens L12 may be set to be convex.

[0084] Preferably, when the radius of curvature of the exit side of the 12th lens is R23, the radius of curvature of the object side of the 12th lens is R24, the focal length of the 12th lens is f12, and the on-axial thickness of the 12th lens is d23, the following conditions (42) to (44) are satisfied. -4.79≦(R23+R24) / (R23-R24)≦-0.41 (42) 0.49 ≤ f12 / f ≤ 2.89 (43) 0.02 ≤ d23 / TTL ≤ 0.08 (44)

[0085] Conditional equation (42) defines the shape of the 12th lens L12, which is advantageous for correcting axial chromatic aberration within that range, and more preferably satisfies the conditional equation -3.00 ≤ (R23 + R24) / (R23 - R24) ≤ -0.51. Conditional equation (43) defines the ratio of the focal length f12 of the 12th lens L12 to the focal length f of the microscope objective lenses 10, 20, 30, and 40, which can improve the optical performance of the microscope objective lenses 10, 20, 30, and 40 within that range, and more preferably satisfies the conditional equation 0.78 ≤ f12 / f ≤ 2.31. Condition (44) defines the on-axial thickness d23 of the 12th lens L12 and contributes to rationally controlling the optical lengths of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the condition 0.04 ≤ d23 / TTL ≤ 0.07.

[0086] In this proposed technology, the 13th lens L13 has an exit side that is concave or convex in the paraxial direction, and an object side that is concave in the paraxial direction. In other selectable technologies, the object side of the 13th lens L13 may be set to be convex.

[0087] Preferably, the radius of curvature of the exit side of the 13th lens L13 is R25, the radius of curvature of the object side of the 13th lens L13 is R26, the focal length of the 13th lens L13 is f13, and the on-axial thickness of the 13th lens L13 is d25. 0.36≦(R25+R26) / (R25-R26)≦2.47 (45) -1.62 ≤ f13 / f ≤ -0.33 (46) 0.01 ≤ d25 / TTL ≤ 0.09 (47)

[0088] Conditional equation (45) defines the shape of the 13th lens L13, and by rationally controlling the shape of the 13th lens L13 within the above range, the degree of deflection after the light rays pass through the 13th lens L13 can be mitigated and aberrations can be effectively reduced, more preferably satisfying the conditional equation 0.58 ≤ (R25 + R26) / (R25 - R26) ≤ 1.98. Conditional equation (46) defines the range of the ratio between the focal length f13 of the 13th lens L13 and the focal length f of the microscope objective lenses 10, 20, 30, and 40, and the optical performance of the microscope objective lenses 10, 20, 30, and 40 can be improved, more preferably satisfying the conditional equation -1.01 ≤ f13 / f ≤ -0.41. Condition (47) defines the on-axial thickness d25 of the 13th lens L13 and contributes to rationally controlling the optical lengths of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the condition 0.01 ≤ d25 / TTL ≤ 0.08.

[0089] In this proposed technology, the object side surface of the 12th lens L12 and the output side surface of the 13th lens L13 are joined to form a cemented lens having a negative refractive force, and the following condition (48) is satisfied. -4.11≦f12_13 / f≦-0.97 (48)

[0090] Conditional equation (48) defines the ratio of the focal length f12_13 of the cemented lens formed by the 12th lens L12 and the 13th lens L13 to the focal length f of the microscope objective lenses 10, 20, 30, and 40, thereby improving the optical performance of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfying the conditional equation -2.57 ≤ f12_13 / f ≤ -1.21.

[0091] In this proposed technology, the 14th lens L14 has a concave surface paraxially on its exit side and a concave surface paraxially on its object side. In other selectable technologies, the object side and exit side of the 14th lens L14 may be configured with other concave / convex distributions.

[0092] Preferably, when the focal length of the 14th lens L14 is f14 and the on-axial thickness of the 14th lens L14 is d27, the following conditions (49) to (50) are satisfied. 0.71 ≤ f14 / f ≤ 3.74 (49) 0.01 ≤ d27 / TTL ≤ 0.15 (50)

[0093] Conditional equation (49) defines the range of the ratio between the focal length of the 14th lens L14 and the focal lengths f of the microscope objective lenses 10, 20, 30, and 40, contributing to the reduction of aberrations and improvement of image quality, and more preferably satisfies the conditional equation 1.13 ≤ f14 / f ≤ 2.99. Conditional equation (50) defines the on-axial thickness d27 of the 14th lens L14, contributing to the rational control of the optical lengths of the microscope objective lenses 10, 20, 30, and 40, and more preferably satisfies the conditional equation 0.02 ≤ d27 / TTL ≤ 0.12.

[0094] In this proposed technology, an aperture ST is installed between the second lens L2 and the third lens L3.

[0095] In this proposed technology, the first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, eighth lens L8, ninth lens L9, tenth lens L10, eleventh lens L11, twelfth lens L12, thirteenth lens L13, and fourteenth lens L14 are all made of glass.

[0096] The microscope objective lenses 10, 20, 30, and 40 of the present invention control the flow of light rays between lenses, make the lens structure compact, control the overall length of the lens so that the imaging range reaches a desired state, provide the microscope objective lens with a high numerical aperture, ensure that the light rays have sufficient focusing ability, and have excellent optical performance, satisfying the design requirements of low distortion, 10x magnification, and long working distance.

[0097] The microscope objective lens 10 according to the present invention will be described below using examples. The reference numerals in each example are as shown in Table 1, and the units of focal length, axial distance, radius of curvature, and axial thickness are millimeters.

[0098] The technical proposal of the present invention will be specifically described below with reference to four embodiments.

[0099] (First Embodiment) In this embodiment, the first lens L1 has a positive refractive power, its emission surface is convex in the paraxial direction, and its object side surface is convex in the paraxial direction. The second lens L2 has a negative refractive power, its emission surface is concave in the paraxial direction, and its object side surface is concave in the paraxial direction. The third lens L3 has a negative refractive power, its emission surface is concave in the paraxial direction, and its object side surface is convex in the paraxial direction. The fourth lens L4 has a negative refractive power, its emission surface is concave in the paraxial direction, and its object side surface is convex in the paraxial direction. Lens L5 (the fifth lens) has a positive refractive power, its emission surface is concave in the paraxial direction, and its object-side surface is convex in the paraxial direction. The sixth lens, L6, has a positive refractive power, its emission surface is convex in the paraxial direction, and its object side surface is convex in the paraxial direction. Lens L7, the seventh lens, has negative refractive power, its exit surface is convex in the paraxial direction, and its object side surface is concave in the paraxial direction. Lens L8 has a positive refractive power, its exit surface is concave in the paraxial direction, and its object side is convex in the paraxial direction. Lens L9 has a positive refractive power, its emission surface is concave in the paraxial direction, and its object-side surface is convex in the paraxial direction. The tenth lens L10 has a positive refractive power, its emission surface is concave in the paraxial direction, and its object side surface is concave in the paraxial direction. Lens L11 has a negative refractive power, its exit surface is concave in the paraxial direction, and its object side surface is convex in the paraxial direction. Lens L12 has a positive refractive power, its emission surface is concave in the paraxial direction, and its object side is concave in the paraxial direction. The 13th lens 13 has a negative refractive power, its emission surface is concave in the paraxial direction, and its object side surface is concave in the paraxial direction. Lens L14 has a positive refractive power, its emission surface is concave in the paraxial direction, and its object side is concave in the paraxial direction.

[0100] Figure 1 is a schematic diagram showing the structure of the microscope objective lens 10 in the first embodiment. The design data for the microscope objective lens 10 in the first embodiment of the present invention is shown below.

[0101] Table 1 shows the radius of curvature R of the output side and object side of the first lens L1 to the 14th lens L14 that constitute the microscope objective lens 10 in the first embodiment of the present invention, the on-axial thickness of the lens, the on-axial distance d between the lenses, the refractive index nd, and the Abbe number vd. In this embodiment, the units of distance, radius, and thickness are all millimeters (mm).

[0102] [Table 1]

[0103] The meanings of each symbol in the table above are as follows: R: Radius of curvature of the optical surface; in the case of a lens, the radius of curvature of the center. ST: Aperture R1: Radius of curvature of the exit side of the first lens L1 R2: Radius of curvature of the object side of the first lens L1 R3: Radius of curvature of the exit side of the second lens L2 R4: Radius of curvature of the object side of the second lens L2 R5: Radius of curvature of the exit side of the third lens L3 R6: Radius of curvature of the object side of the third lens L3 R7: Radius of curvature of the exit side of the fourth lens L4 R8: Radius of curvature of the object side of the fourth lens L4 R9: Radius of curvature of the exit side of the fifth lens L5 R10: Radius of curvature of the object side of lens L5 (5th lens) R11: Radius of curvature of the exit side of the sixth lens L6. R12: Radius of curvature of the object side of lens L6 (6th lens) R13: Radius of curvature of the exit side of lens L7 (7th lens) R14: Radius of curvature of the object side of lens L7 (7th lens) R15: Radius of curvature of the exit side of lens L8 (No. 8) R16: Radius of curvature of the object side of lens L8 (8th lens) R17: Radius of curvature of the exit side of lens L9 (9th lens) R18: Radius of curvature of the object side of lens L9 (L9) R19: Radius of curvature of the exit side of the 10th lens L10 R20: Radius of curvature of the object side of the 10th lens L10 R21: Radius of curvature of the exit side of lens L11 (11th lens) R22: Radius of curvature of the object side of lens L11 (11th lens) R23: Radius of curvature of the exit side of lens L12 (No. 12) R24: Radius of curvature of the object side of lens L12 (L12) R25: Radius of curvature of the exit side of lens L13 (13th lens) R26: Radius of curvature of the object side of lens L13 (13th lens) R27: Radius of curvature of the exit side of lens L14 (14th lens) R28: Radius of curvature of the object side of lens L14 (14th lens) d: Axial thickness of the lens, axial distance between lenses d1: Axial thickness of the first lens L1 d2: On-axis distance from the exit side of the first lens L1 to the object side of the second lens L2. d3: Axial thickness of the second lens L2 d41: Axial distance from the exit side of the second lens L2 to the aperture ST d42: On-axis distance from aperture ST to the side of the object on the third lens L3 d5: Axial thickness of the third lens L3 d6: On-axis distance from the exit side of the third lens L3 to the object side of the fourth lens L4. d7: Axial thickness of the fourth lens L4 d8: On-axis distance from the exit side of the fourth lens L4 to the object side of the fifth lens L5. d9: Axial thickness of the 5th lens L5 d10: On-axis distance from the exit side of the 5th lens L5 to the object side of the 6th lens L6. d11: Axial thickness of the 6th lens L6 d12: On-axis distance from the exit side of the 6th lens L6 to the object side of the 7th lens L7. d13: Axial thickness of lens L7 (7th lens) d14: On-axis distance from the exit side of lens 7 L7 to the object side of lens 8 L8. d15: Axial thickness of lens L8 (8th lens) d16: On-axis distance from the exit side of the 8th lens L8 to the object side of the 9th lens L9. d17: Axial thickness of lens L9 (9th lens) d18: On-axis distance from the exit side of the 9th lens L9 to the object side of the 10th lens L10. d19: Axial thickness of lens L10 (10th lens) d20: On-axis distance from the exit side of the 10th lens L10 to the object side of the 11th lens L11. d21: Axial thickness of lens L11 (11th lens) d22: On-axis distance from the exit side of the 11th lens L11 to the object side of the 12th lens L12. d23: Axial thickness of lens L12 (12th lens) d24: On-axis distance from the exit side of the 12th lens L12 to the object side of the 13th lens L13. d25: Axial thickness of lens L13 (13th lens) d26: On-axis distance from the exit side of the 13th lens L13 to the object side of the 14th lens L14. d27: Axial thickness of lens L14 (14th lens) d28: On-axis distance from the side of the object to the object plane obj of lens L14 (L14) nd: Refractive index of the d-line (the d-line is green light with a wavelength of 550 nm) nd1: Refractive index of the d line of the first lens L1 nd2: Refractive index of the d line of the second lens L2 nd3: Refractive index of the d line of the third lens L3 nd4: Refractive index of the d line of lens L4 (4th lens) nd5: Refractive index of the d line of lens L5 (5th lens) nd6: Refractive index of the d line of lens L6 (6th lens) nd7: Refractive index of the d line of lens L7 (7th lens) nd8: Refractive index of the d line of lens L8 (8th lens) nd9: Refractive index of the d line of lens L9 (lens 9). nd10: Refractive index of the d line of lens L10 (10th lens) nd11: Refractive index of the d line of lens L11 (lens number 11) nd12: Refractive index of the d line of lens L12 (lens number 12) nd13: Refractive index of the d line of lens L13 (lens number 13) nd14: Refractive index of the d line of lens L14 (lens number 14) vd: Abbe number vd1: Abbe number of the first lens L1 vd2: Abbe number of the second lens L2 vd3: Abbe number of the third lens L3 vd4: Abbe number of lens L4 (fourth lens) vd5: Abbe number of lens L5 (5th lens) vd6: Abbe number of lens L6 (6th lens) vd7: Abbe number of lens L7 (7th lens) vd8: Abbe number of lens L8 (8th lens) vd9: Abbe number of lens L9 (9th lens) vd10: Abbe number of lens L10 (10th lens) vd11: Abbe number of lens L11 (lens number 11) vd12: Abbe number of lens L12 (lens number 12) vd13: Abbe number of lens L13 (lens number 13) vd14: Abbe number of lens L14 (lens number 14)

[0104] Figure 2 is a schematic diagram showing the field curvature and distortion aberration after light with a wavelength of 588 nm passes through the objective lens 10 for a microscope according to the first embodiment, where S is the field curvature in the sagittal direction and T is the field curvature in the tangential direction; Figure 3 is a schematic diagram showing the lateral chromatic aberration after light with wavelengths of 420 nm, 486 nm, 588 nm and 656 nm passes through the objective lens 10 for a microscope according to the first embodiment; and Figure 4 is a schematic diagram showing the axial chromatic aberration after light with wavelengths of 420 nm, 486 nm, 588 nm and 656 nm passes through the objective lens 10 for a microscope according to the first embodiment.

[0105] Furthermore, Table 5 below shows the values ​​corresponding to the various parameters and conditional expressions in the first embodiment.

[0106] As shown in Table 5, the first embodiment satisfies each of the conditions.

[0107] In this embodiment, the entrance pupil diameter of the microscope objective lens 10 is 19.208 mm, the total field of view image height is 1.65 mm, and the numerical aperture (NA) is 0.48. The microscope objective lens 10 can control the flow of light rays between the lenses, contributing to smooth propagation after the light rays enter the lens group, making the lens structure compact, controlling the overall length of the lenses so that the imaging range reaches a desired state, ensuring that the microscope objective lens 10 has a high numerical aperture (NA), that the light rays have sufficient focusing ability, and that it has excellent optical performance, satisfying the design requirements of low distortion, 10x magnification, and long working distance.

[0108] (Second Embodiment) Figure 5 is a schematic diagram showing the configuration of the microscope objective lens 20 in the second embodiment. The second embodiment is basically the same as the first embodiment, and the meaning of the reference numerals is the same as in the first embodiment, so only the differences are shown below.

[0109] In this embodiment, the 12th lens L12 has a convex surface in the paraxial direction on the side surface of the object, and the 13th lens L13 has a convex surface in the paraxial direction on the side surface of the emission.

[0110] Table 2 shows the design data for the microscope objective lens 20 according to the second embodiment of the present invention.

[0111] [Table 2]

[0112] Figure 6 is a schematic diagram showing the field curvature and distortion aberration after light with a wavelength of 588 nm passes through the objective lens 20 for a microscope according to the second embodiment, where S is the field curvature in the sagittal direction and T is the field curvature in the tangential direction. Figure 7 is a schematic diagram showing the lateral chromatic aberration after light with wavelengths of 420 nm, 486 nm, 588 nm, and 656 nm passes through the objective lens 20 for a microscope according to the second embodiment, and Figure 8 is a schematic diagram showing the axial chromatic aberration after light with wavelengths of 420 nm, 486 nm, 588 nm, and 656 nm passes through the objective lens 20 for a microscope according to the second embodiment.

[0113] Furthermore, Table 5 below shows the values ​​corresponding to the various parameters and conditional expressions in the second embodiment.

[0114] As shown in Table 5, the second embodiment satisfies each of the conditions.

[0115] In this embodiment, the entrance pupil diameter of the microscope objective lens 20 is 19.208 mm, the total field of view image height is 1.65 mm, and the numerical aperture is 0.48. The microscope objective lens 20 can control the flow of light rays between the lenses, contributing to smooth propagation after the light rays enter the lens group, making the lens structure compact, controlling the overall length of the lenses so that the imaging range reaches a desired state, ensuring that the microscope objective lens 20 has a high numerical aperture (NA), that the light rays have sufficient focusing ability, and that it has excellent optical performance, satisfying the design requirements of low distortion, 10x magnification, and long working distance.

[0116] (Third embodiment) Figure 9 is a schematic diagram showing the configuration of the microscope objective lens 30 in the third embodiment. The third embodiment is basically the same as the first embodiment, and the meaning of the reference numerals is the same as in the first embodiment, so only the differences are shown below.

[0117] Table 3 shows the design data for the microscope objective lens 30 according to the third embodiment of the present invention.

[0118] [Table 3]

[0119] Figure 10 is a schematic diagram showing the field curvature and distortion after light with a wavelength of 588 nm passes through the objective lens 30 for a microscope according to the third embodiment, where S is the field curvature in the sagittal direction and T is the field curvature in the tangential direction. Figure 11 is a schematic diagram showing the chromatic aberration after light with wavelengths of 420 nm, 486 nm, 588 nm, and 656 nm passes through the objective lens 30 for a microscope according to the third embodiment, and Figure 12 is a schematic diagram showing the axial chromatic aberration after light with wavelengths of 420 nm, 486 nm, 588 nm, and 656 nm passes through the objective lens 30 for a microscope according to the third embodiment.

[0120] Furthermore, Table 5 below shows the values ​​corresponding to the various parameters and conditional expressions in the third embodiment.

[0121] As shown in Table 5, the third embodiment satisfies each of the conditions.

[0122] In this embodiment, the entrance pupil diameter of the microscope objective lens 30 is 19.000 mm, the total field image height is 1.65 mm, and the numerical aperture (NA) is 0.475. The microscope objective lens 30 can control the flow of light rays between the lenses, contributing to smooth propagation after the light rays enter the lens group, making the lens structure compact, controlling the overall length of the lenses so that the imaging range reaches a desired state, ensuring that the microscope objective lens 30 has a high numerical aperture (NA), that the light rays have sufficient focusing ability, and that it has excellent optical performance, satisfying the design requirements of low distortion, 10x magnification, and long working distance.

[0123] (Fourth Embodiment) Figure 13 is a schematic diagram showing the configuration of the microscope objective lens 40 in the fourth embodiment. The fourth embodiment is basically the same as the first embodiment, and the meaning of the reference numerals is the same as in the first embodiment, so only the differences are shown below.

[0124] In this embodiment, the eighth lens L8 has a negative refractive power, and the object side surface of the eighth lens L8 is concave in the paraxial direction.

[0125] Table 4 shows the design data for the microscope objective lens 40 according to the fourth embodiment of the present invention.

[0126] [Table 4]

[0127] Figure 14 is a schematic diagram showing the field curvature and distortion after light with a wavelength of 555 nm passes through the objective lens 40 for a microscope according to the fourth embodiment, where S is the field curvature in the sagittal direction and T is the field curvature in the tangential direction. Figure 15 is a schematic diagram showing the chromatic aberration after light with wavelengths of 420 nm, 486 nm, 588 nm, and 656 nm passes through the objective lens 40 for a microscope according to the fourth embodiment, and Figure 16 is a schematic diagram showing the axial chromatic aberration after light with wavelengths of 420 nm, 486 nm, 588 nm, and 656 nm passes through the objective lens 40 for a microscope according to the fourth embodiment.

[0128] Furthermore, Table 5 below shows the values ​​corresponding to the various parameters and conditional expressions in the fourth embodiment.

[0129] As shown in Table 5, the fourth embodiment satisfies each of the conditions.

[0130] In this embodiment, the entrance pupil diameter of the microscope objective lens 40 is 19.200 mm, the total field image height is 1.65 mm, and the numerical aperture (NA) is 0.480. The microscope objective lens 40 can control the flow of light rays between the lenses, contributing to smooth propagation after the light rays enter the lens group, making the lens structure compact, controlling the overall length of the lenses so that the imaging range reaches a desired state, ensuring that the microscope objective lens 40 has a high numerical aperture (NA), that the light rays have sufficient focusing ability, and that it has excellent optical performance, satisfying the design requirements of low distortion, 10x magnification, and long working distance.

[0131] Table 5 shows the numerical values ​​corresponding to each condition in the comparative embodiment according to the above condition formulas.

[0132] [Table 5]

[0133] The above describes in detail an objective lens for a microscope according to an embodiment of the present invention. While specific examples have been used to illustrate the principles and embodiments of the present invention, these examples are merely intended to aid in understanding the concept of the invention, and specific embodiments and applications may be modified as appropriate. Therefore, the contents of this specification should not be understood as limitations on the present invention.

Claims

1. A microscope objective lens, The microscope objective lens is composed of, in order from the output side to the object side, a first lens having positive refractive power, a second lens having negative refractive power, a third lens having negative refractive power, a fourth lens having negative refractive power, a fifth lens having positive refractive power, a sixth lens having positive refractive power, a seventh lens having negative refractive power, an eighth lens having positive or negative refractive power, a ninth lens having positive refractive power, a tenth lens having positive refractive power, an eleventh lens having negative refractive power, a twelfth lens having positive refractive power, a thirteenth lens having negative refractive power, and a fourteenth lens having positive refractive power, and the focal length of the ninth lens... A microscope objective lens characterized by satisfying the following conditions (1) to (5), where f is f9, the combined focal length of the 10th lens and the 11th lens is f10_11, the combined focal length of the 12th lens and the 13th lens is f12_13, the radius of curvature of the exit side of the 14th lens is R27, the radius of curvature of the object side of the 14th lens is R28, the focal length of the microscope objective lens is f, the on-axial distance from the object surface of the microscope objective lens to the object side of the 14th lens is WD, the on-axial distance from the object surface of the microscope objective lens to the exit surface of the first lens is TTL, and the numerical aperture of the microscope objective lens is NA. 1.60 ≤ f9 / f ≤ 4.00 (1) -3.00≦f10_11 / f12_13≦-1.40 (2) -9.00≦(R27+R28) / (R27-R28)≦-1.60 (3) 0.05 ≤ WD / TTL ≤ 0.13 (4) 2.40 ≤ WD * NA ≤ 5.50 (5)

2. The microscope objective lens according to claim 1, characterized in that the object side of the fourth lens and the output side of the fifth lens are joined to form a first bonded lens, the object side of the seventh lens and the output side of the eighth lens are joined to form a second bonded lens, the object side of the tenth lens and the output side of the eleventh lens are joined to form a third bonded lens, and the object side of the twelfth lens and the output side of the thirteenth lens are joined to form a fourth bonded lens, wherein the difference in Abbe numbers of the two lenses in any one of the bonded lenses is Δv, and the following condition (6) is satisfied. Δv ≥ 35.00 (6)

3. The first lens has an exit side that is convex in the paraxial direction, and an object side that is convex in the paraxial direction. The microscope objective lens according to claim 1, characterized in that, when 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 focal length of the first lens is f1, and the on-axial thickness of the first lens is d1, the following conditional equations (7) to (9) are satisfied. -1.57≦(R1+R2) / (R1-R2)≦0.00 (7) 0.67 ≤ f1 / f ≤ 3.23 (8) 0.01 ≤ d1 / TTL ≤ 0.07 (9)

4. The second lens has an exit side that is concave in the paraxial direction, and an object side that is concave in the paraxial direction. The microscope objective lens according to claim 1, characterized in that, when 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 focal length of the second lens is f2, and the on-axial thickness of the second lens is d3, the following conditional equations (10) to (12) are satisfied. 0.22≦(R3+R4) / (R3-R4)≦1.38 (10) -2.41 ≤ f² / f ≤ -0.71 (11) 0.01 ≤ d3 / TTL ≤ 0.02 (12)

5. The third lens has an exit side that is concave in the paraxial direction and an object side that is convex in the paraxial direction. The microscope objective lens according to claim 1, characterized in that, when the radius of curvature of the exit side surface of the third lens is R5, the radius of curvature of the object side surface of the third lens is R6, the focal length of the third lens is f3, and the on-axial thickness of the third lens is d5, the following conditional equations (13) to (15) are satisfied. -7.51≦(R5+R6) / (R5-R6)≦-1.63 (13) -4.33 ≤ f³ / f ≤ -1.18 (14) 0.01 ≤ d5 / TTL ≤ 0.08 (15)

6. The fourth lens has an exit side that is concave in the paraxial direction and an object side that is convex in the paraxial direction. The microscope objective lens according to claim 1, characterized in that, when the radius of curvature of the exit side surface of the fourth lens is R7, the radius of curvature of the object side surface of the fourth lens is R8, the focal length of the fourth lens is f4, and the on-axial thickness of the fourth lens is d7, the following conditional equations (16) to (18) are satisfied. 0.61≦(R7+R8) / (R7-R8)≦2.26 (16) -5.94 ≤ f₄ / f ≤ -1.57 (17) 0.04 ≤ d7 / TTL ≤ 0.16 (18)

7. The fifth lens has an exit side that is concave in the paraxial direction and an object side that is convex in the paraxial direction. The microscope objective lens according to claim 1, characterized in that, when the radius of curvature of the exit side surface of the fifth lens is R9, the radius of curvature of the object side surface of the fifth lens is R10, the focal length of the fifth lens is f5, and the on-axial thickness of the fifth lens is d9, the following conditional equations (19) to (21) are satisfied. -9.50≦(R9+R10) / (R9-R10)≦-2.61 (19) 1.09 ≤ f5 / f ≤ 3.49 (20) 0.01 ≤ d9 / TTL ≤ 0.06 (21)

8. The objective lens for a microscope according to claim 1, characterized in that the object side of the fourth lens and the output side of the fifth lens are joined to form a cemented lens having a positive refractive power, and the following conditional equation (22) is satisfied when the combined focal length of the fourth lens and the fifth lens is f4_5. 1.35 ≤ f₄_5 / f ≤ 4.75 (22)

9. The sixth lens has an exit side that is convex in the paraxial direction, and an object side that is convex in the paraxial direction. The microscope objective lens according to claim 1, characterized in that, when 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 focal length of the sixth lens is f6, and the on-axial thickness of the sixth lens is d11, the following conditional equations (23) to (25) are satisfied. 0.18≦(R11+R12) / (R11-R12)≦1.26 (23) 0.98 ≤ f6 / f ≤ 3.59 (24) 0.02 ≤ d11 / TTL ≤ 0.14 (25)

10. The seventh lens has a convex surface in the paraxial direction on its exit side and a concave surface in the paraxial direction on its object side. The microscope objective lens according to claim 1, characterized in that, when 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 focal length of the seventh lens is f7, and the on-axial thickness of the seventh lens is d13, the following conditional equations (26) to (28) are satisfied. -0.43≦(R13+R14) / (R13-R14)≦0.25 (26) -4.27 ≤ f7 / f ≤ -1.15 (27) 0.01 ≤ d13 / TTL ≤ 0.04 (28)

11. The eighth lens has a concave surface in the paraxial direction on its exit side. The microscope objective lens according to claim 1, characterized in that, when 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 focal length of the eighth lens is f8, and the on-axial thickness of the eighth lens is d15, the following conditional equations (29) to (31) are satisfied. -3.39≦(R15+R16) / (R15-R16)≦0.11 (29) -7.32 ≤ f8 / f ≤ 20.86 (30) 0.03 ≤ d15 / TTL ≤ 0.17 (31)

12. The objective lens for a microscope according to claim 1, characterized in that the object side of the seventh lens and the output side of the eighth lens are joined to form a bonded lens having negative refractive power, and when the combined focal length of the seventh lens and the eighth lens is f7_8, the following conditional equation (32) is satisfied. -9.03 ≤ f7_8 / f ≤ -0.95 (32)

13. The ninth lens has an exit side that is concave in the paraxial direction and an object side that is convex in the paraxial direction. The microscope objective lens according to claim 1, characterized in that when the exit side surface of the ninth lens has a radius of curvature of R17, the radius of curvature of the object side surface of the ninth lens is R18, and the on-axial thickness of the ninth lens is d17, the following conditional equations (33) to (34) are satisfied. -0.06≦(R17+R18) / (R17-R18)≦0.60 (33) 0.03 ≤ d17 / TTL ≤ 0.17 (34)

14. The tenth lens has an exit side that is concave in the paraxial direction, and an object side that is concave in the paraxial direction. The microscope objective lens according to claim 1, characterized in that, when the radius of curvature of the exit side surface of the 10th lens is R19, the radius of curvature of the object side surface of the 10th lens is R20, the focal length of the 10th lens is f10, and the on-axial thickness of the 10th lens is d19, the following conditional equations (35) to (37) are satisfied. 2.10≦(R19+R20) / (R19-R20)≦8.39 (35) 1.83 ≤ f10 / f ≤ 7.29 (36) 0.01 ≤ d19 / TTL ≤ 0.02 (37)

15. The 11th lens has an exit side that is concave in the paraxial direction and an object side that is convex in the paraxial direction. The microscope objective lens according to claim 1, characterized in that, when the radius of curvature of the exit side surface of the 11th lens is R21, the radius of curvature of the object side surface of the 11th lens is R22, the focal length of the 11th lens is f11, and the on-axial thickness of the 11th lens is d21, the following conditional equations (38) to (40) are satisfied. -1.80≦(R21+R22) / (R21-R22)≦-0.38 (38) -13.59 ≤ f11 / f ≤ -1.56 (39) 0.05 ≤ d21 / TTL ≤ 0.19 (40)

16. The microscope objective lens according to claim 1, characterized in that the object side surface of the tenth lens and the output side surface of the eleventh lens are joined to form a bonded lens having a positive refractive power, and the following conditional equation (41) is satisfied. 1.25 ≤ f10_11 / f ≤ 6.42 (41)

17. The 12th lens has a concave surface in the paraxial direction on its exit side. The microscope objective lens according to claim 1, characterized in that, when the radius of curvature of the exit side surface of the 12th lens is R23, the radius of curvature of the object side surface of the 12th lens is R24, the focal length of the 12th lens is f12, and the on-axial thickness of the 12th lens is d23, the following conditional equations (42) to (44) are satisfied. -4.79≦(R23+R24) / (R23-R24)≦-0.41 (42) 0.49 ≤ f12 / f ≤ 2.89 (43) 0.02 ≤ d23 / TTL ≤ 0.08 (44)

18. The 13th lens has a concave surface on the paraxial side of the object, The microscope objective lens according to claim 1, characterized in that, when the radius of curvature of the exit side surface of the 13th lens is R25, the radius of curvature of the object side surface of the 13th lens is R26, the focal length of the 13th lens is f13, and the on-axial thickness of the 13th lens is d25, the following conditional equations (45) to (47) are satisfied. 0.36≦(R25+R26) / (R25-R26)≦2.47 (45) -1.62 ≤ f13 / f ≤ -0.33 (46) 0.01 ≤ d25 / TTL ≤ 0.09 (47)

19. The microscope objective lens according to claim 1, characterized in that the object side surface of the 12th lens and the output side surface of the 13th lens are joined to form a bonded lens having a negative refractive power, and the following conditional equation (48) is satisfied. -4.11 ≤ f12_13 / f ≤ -0.97 (48)

20. The 14th lens has an exit side that is concave in the paraxial direction, and an object side that is concave in the paraxial direction. The microscope objective lens according to claim 1, characterized in that, when the focal length of the 14th lens is f14 and the on-axial thickness of the 14th lens is d27, the following conditional equations (49) to (50) are satisfied. 0.71 ≤ f14 / f ≤ 3.74 (49) 0.01 ≤ d27 / TTL ≤ 0.15 (50)

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