Objective lens for microscope

Abstract

To provide an objective lens for a microscope relating to a field of an optical lens.SOLUTION: An objective lens for a microscope consists of, in order from an object side to an image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens and satisfies conditional expressions 0.19≤WD / TTL≤0.36, 4.00≤NA*f≤8.00, 7.00≤f678 / f9≤16.00, -10.00≤(R17+R18) / (R17-R18)≤-1.50. The objective lens for a microscope of the present invention has an optical performance of excellent image formation quality and also meets requirements for a wide operation band and high magnification.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the field of optical lenses, in particular to objective lenses for microscopes applied in industrial microscopes. [Background technology]

[0002] A microscope objective lens can complete its specific imaging function with a certain angle of view, focal length, and aperture diameter, but it is limited by the optical imaging principle, and these optical characteristic parameters are mutually constrained. A microscope objective lens needs to have the characteristic that a large numerical aperture brings high resolution, but the higher the magnification of the microscope objective lens, the larger the numerical aperture, and the more significant the impact of the thickness and refractive index changes on the imaging quality of the microscope, so it is usually difficult to have high imaging quality and high magnification at the same time. In addition, with the development of technology and the increasing diversification needs of users, when the system's requirements for imaging quality are increasing, a nine-piece lens structure gradually appears in the design of the lens. There is a demand for a microscope objective lens with good optical performance and a wide operating band and high magnification. Summary of the Invention [Problem to be solved by the invention]

[0003] In view of the above problems, an object of the present invention is to provide an objective lens for a microscope that can satisfy the requirements for a wide operating band and a high magnification while obtaining optical performance with good imaging quality. [Means for solving the problem]

[0004] In order to solve the above technical problem, an embodiment of the present invention provides a microscope objective lens, which is composed of, in order from the object side to the image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens, When the distance from the object side surface of the first lens to the object to be observed is WD, the optical length of the microscope objective lens is TTL, the object side numerical aperture of the microscope objective lens is NA, the focal length of the microscope objective lens is f, the equivalent focal length of the sixth lens, the seventh lens, and the eighth lens is f678, the focal length of the ninth lens is f9, the radius of curvature of the object side surface of the ninth lens is R17, and the radius of curvature of the image side surface of the ninth lens is R18, the following conditional formulas (1) to (4) are satisfied. 0.19≦WD / TTL≦0.36 (1) 4.00≦NA*f≦8.00 (2) 7.00≦f678 / f9≦16.00 (3) -10.00≦(R17+R18) / (R17-R18)≦-1.50 (4)

[0005] It is preferable that, when the refractive index of the second lens is n2, the following conditional expression (5) is satisfied: n2≧2.00 (5)

[0006] It is preferable that, when the focal length of the third lens is f3, the following conditional expression (6) be satisfied: 3.00≦f3 / f≦6.00 (6)

[0007] Preferably, the first lens has negative refractive power, an object side surface of the first lens is a paraxial concave surface, and an image side surface of the first lens is a paraxial concave surface, When the focal length of the first lens is f1, the radius of curvature of the object side surface of the first lens is R1, the radius of curvature of the image side surface of the first lens is R2, and the axial thickness of the first lens is d1, the following conditional expressions (7) to (9) are satisfied. -2.20≦f1 / f≦-0.70 (7) -0.42≦(R1+R2) / (R1-R2)≦-0.16 (8) 0.01≦d1 / TTL≦0.02 (9)

[0008] Preferably, the second lens has positive refractive power, and an object side surface of the second lens is convex on a paraxial line, When the focal length of the second lens is f2, the radius of curvature of the object side surface of the second lens is R3, the radius of curvature of the image side surface of the second lens is R4, and the axial thickness of the second lens is d3, the following conditional expressions (10) to (12) are satisfied. 1.58≦f2 / f≦11.25 (10) -1.85≦(R3+R4) / (R3-R4)≦-0.49 (11) 0.01≦d3 / TTL≦0.05 (12)

[0009] Preferably, the third lens has a positive refractive power, an object side surface of the third lens is a concave surface in a paraxial direction, and an image side surface of the third lens is a convex surface in a paraxial direction, When the radius of curvature of the object side surface of the third lens is R5, the radius of curvature of the image side surface of the third lens is R6, and the axial thickness of the third lens is d5, the following conditional expressions (13) and (14) are satisfied. 4.50≦(R5+R6) / (R5−R6)≦34.00 (13) 0.15≦d5 / TTL≦0.17 (14)

[0010] Preferably, the fourth lens has negative refractive power, and an image side surface of the fourth lens is concave in a paraxial direction; When the focal length of the fourth lens is f4 and the on-axis thickness of the fourth lens is d7, the following conditional expressions (15) and (16) are satisfied. -54.00≦f4 / f≦-2.68 (15) 0.02≦d7 / TTL≦0.15 (16)

[0011] Preferably, the fifth lens has a positive refractive power, an object side surface of the fifth lens is a convex surface on a paraxial line, and an image side surface of the fifth lens is a convex surface on a paraxial line, When the focal length of the fifth lens is f5, the radius of curvature of the object side surface of the fifth lens is R9, the radius of curvature of the image side surface of the fifth lens is R10, and the axial thickness of the fifth lens is d9, the following conditional expressions (17) to (19) are satisfied. 1.80≦f5 / f≦9.03 (17) -0.13≦(R9+R10) / (R9−R10)≦0.09 (18) 0.05≦d9 / TTL≦0.07 (19)

[0012] Preferably, the sixth lens has a positive refractive power, an object side surface of the sixth lens is a convex surface on a paraxial line, and an image side surface of the sixth lens is a convex surface on a paraxial line, When the focal length of the sixth lens is f6, the radius of curvature of the object side surface of the sixth lens is R11, the radius of curvature of the image side surface of the sixth lens is R12, and the axial thickness of the sixth lens is d11, the following conditional expressions (20) to (22) are satisfied. 2.07≦f6 / f≦8.00 (20) -0.39≦(R11+R12) / (R11-R12)≦-0.14 (21) 0.07≦d11 / TTL≦0.12 (22)

[0013] Preferably, the seventh lens has negative refractive power, an object side surface of the seventh lens is a paraxial concave surface, and an image side surface of the seventh lens is a paraxial concave surface, When the focal length of the seventh lens is f7, the radius of curvature of the object side surface of the seventh lens is R13, the radius of curvature of the image side surface of the seventh lens is R14, and the axial thickness of the seventh lens is d13, the following conditional expressions (23) to (25) are satisfied. -2.09≦f7 / f≦-1.09 (23) 0.11≦(R13+R14) / (R13−R14)≦0.38 (24) 0.01≦d13 / TTL≦0.02 (25)

[0014] Preferably, an object side surface of the eighth lens is a convex surface on a paraxial line, and an image side surface of the eighth lens is a convex surface on a paraxial line, When the focal length of the eighth lens is f8, the central radius of curvature of the object side surface of the eighth lens is R15, the central radius of curvature of the image side surface of the eighth lens is R16, and the axial thickness of the eighth lens is d15, the following conditional expressions (26) to (28) are satisfied. -9.96≦f8 / f≦2.36 (26) -0.55≦(R15+R16) / (R15-R16)≦-0.31 (27) 0.02≦d15 / TTL≦0.07 (28)

[0015] Preferably, the ninth lens has a positive refractive power, an object side surface of the ninth lens is a convex surface on a paraxial line, and an image side surface of the ninth lens is a concave surface on a paraxial line; When the focal length of the ninth lens is f9 and the axial thickness of the eighth lens is d17, the following conditional expressions (29) and (30) are satisfied. 1.77≦f9 / f≦2.31 (29) 0.06≦d17 / TTL≦0.13 (30)

[0016] Preferably, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are all made of a glass material. Effect of the Invention

[0017] The beneficial effects of the present invention are as follows: The microscope objective lens according to the present invention has optical performance with good imaging quality, and can meet the requirements of wide operating band and high magnification, and is especially applicable to industrial microscopes. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic diagram showing a configuration of a microscope objective lens according to a first embodiment of the present invention. [Diagram 2] 2 is a schematic diagram showing the axial chromatic aberration of the microscope objective lens shown in FIG. 1. [Diagram 3] 2 is a schematic diagram showing lateral chromatic aberration of the microscope objective lens shown in FIG. 1. [Figure 4] 2 is a schematic diagram showing the field curvature and distortion of the microscope objective lens shown in FIG. 1. [Diagram 5]FIG. 4 is a schematic diagram showing the configuration of a microscope objective lens according to a second embodiment of the present invention. [Figure 6] 6 is a schematic diagram showing the axial chromatic aberration of the microscope objective lens shown in FIG. 5. [Figure 7] 6 is a schematic diagram showing lateral chromatic aberration of the microscope objective lens shown in FIG. 5. [Figure 8] 6 is a schematic diagram showing the field curvature and distortion of the microscope objective lens shown in FIG. 5. [Figure 9] FIG. 4 is a schematic diagram showing the configuration of a microscope objective lens according to a third embodiment of the present invention. [Figure 10] 10 is a schematic diagram showing the axial chromatic aberration of the microscope objective lens shown in FIG. [Figure 11] 10 is a schematic diagram showing chromatic aberration of magnification of the microscope objective lens shown in FIG. [Figure 12] 10 is a schematic diagram showing the field curvature and distortion of the microscope objective lens shown in FIG. 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] In order to make the objectives, solutions and advantages of the present invention clearer, the following describes in detail each embodiment of the present invention with reference to the drawings. However, it is understood by 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 invention. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution claimed by the present invention can be realized.

[0020] (First embodiment) Referring to the drawings, the present invention provides a microscope objective lens 10. FIG. 1 shows a microscope objective lens 10 according to a first embodiment of the present invention, and the microscope objective lens 10 includes nine lenses. Specifically, the microscope objective lens 10 includes, in order from the object side to the image side, a first lens L1, a second lens L2, an aperture S1, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9. An optical element such as an optical filter may be provided between the ninth lens L9 and an image surface Si.

[0021] If the distance from the object side of the first lens L1 to the object to be observed is defined as WD and the optical length of the microscope objective lens L2 is defined as TTL, then the conditional formula 0.19≦WD / TTL≦0.36 is satisfied, specifying the ratio of the distance WD from the object side of the first lens L1 to the object to be observed to the optical length TTL, and within the range of the conditional formula, an appropriate distance can be secured between the microscope objective lens L2 and the object to be observed, making the microscope objective lens L2 easy to handle and allowing the lenses of the microscope objective lens L2 to be arranged in a reasonable space so that aberrations are corrected.

[0022] If the object-side numerical aperture of the microscope objective lens 10 is defined as NA and the focal length of the microscope objective lens 10 as f, then the conditional formula 4.00≦NA*f≦8.00 is satisfied. This conditional formula specifies the range of the product of the object-side numerical aperture NA and the focal length f, and within the range of the conditional formula, the magnification of the microscope objective lens 10 can be maintained and a wider field of view can be obtained.

[0023] If the equivalent focal length of the sixth lens L6, the seventh lens L7, and the eighth lens L8 is defined as f678, and the focal length of the ninth lens L9 is defined as f9, then the conditional formula 7.00≦f678 / f9≦16.00 is satisfied, which specifies the ratio of the focal length of the second lens group on the object side, i.e., the equivalent focal length f678 of the sixth lens L6, the seventh lens L7, and the eighth lens L8 to the focal length f9 of the ninth lens L9. By rationally distributing the optical focal length of the microscope objective lens 10, the light rays can be propagated smoothly, and the microscope objective lens 10 has excellent imaging quality and low sensitivity.

[0024] If the radius of curvature of the object side surface of the ninth lens L9 is defined as R17 and the radius of curvature of the image side surface of the ninth lens L9 is defined as R18, the conditional formula -10.00≦(R17+R18) / (R17-R18)≦-1.50 is satisfied, the shape of the ninth lens L9 is defined, the degree of deflection of the light entering the microscope objective lens 10 can be effectively controlled, and the chromatic aberration can be effectively reduced to chromatic aberration |LC|≦1.0 μm.

[0025] When the distance from the object side surface of the first lens L1 of the microscope objective lens 10 of the present invention to the object to be observed, the optical length, the object-side numerical aperture, the focal length of the microscope objective lens, the focal length of the associated lenses, the radius of curvature of the object side surface and the radius of curvature of the image side surface of the associated lenses satisfy the above conditional expressions, the microscope objective lens 10 has good optical performance, a wide operating band and a high magnification, and the magnification can be made to be 10 or more.

[0026] If the refractive index of the second lens L2 is defined as n2, the conditional formula n2≧2.00 is satisfied, which specifies the refractive index of the second lens L2 of the microscope objective lens 10. It is preferable to select and use a high refractive index material for the tip lens of the microscope objective lens 10, which is advantageous for reducing the aperture of the tip lens and improving the imaging quality of the microscope objective lens 10.

[0027] When the focal length of the third lens L3 is defined as f3, the conditional formula 3.00≦f3 / f≦6.00 is satisfied, and the ratio of the focal length f3 of the third lens L3 to the focal length f of the microscope objective lens 10 is specified. Within the range of the conditional formula, the deflection degree of the light entering the image side first lens group can be effectively controlled, and the distortion aberration of the microscope objective lens 10 can be effectively controlled, and the distortion aberration is |Distortion|≦0.7%, so that the image is not distorted in a wide field of view. In this embodiment, the first lens L1 is made of a glass material, the second lens L2 is made of a glass material, the third lens L3 is made of a glass material, the fourth lens L4 is made of a glass material, the fifth lens L5 is made of a glass material, the sixth lens L6 is made of a glass material, the seventh lens L7 is made of a glass material, the eighth lens L8 is made of a glass material, and the ninth lens L9 is made of a glass material.

[0028] In this embodiment, the object side surface of the first lens L1 is a paraxial concave surface, and the image side surface of the first lens L1 is a paraxial concave surface, and the first lens L1 has a negative refractive power. In other optional embodiments, the object side surface and the image side surface of the first lens L1 may be arranged in other concave-convex distribution situations, and the first lens L1 may have a positive refractive power.

[0029] If the focal length of the first lens L1 is defined as f1, the conditional formula -2.20≦f1 / f≦-0.70 is satisfied, and the refractive power is reasonably distributed, so that the system has excellent imaging quality and low sensitivity.

[0030] If the radius of curvature of the object side surface of the first lens L1 is defined as R1 and the radius of curvature of the image side surface of the first lens L1 is defined as R2, then the conditional formula -0.42≦(R1+R2) / (R1-R2)≦-0.16 is satisfied, and by rationally controlling the shape of the first lens L1, the first lens L1 can effectively correct the system spherical aberration.

[0031] If the axial thickness of the first lens L1 is defined as d1, the condition 0.01≦d1 / TTL≦0.02 is satisfied, which is advantageous for controlling the lens thickness and overall lens length.

[0032] In this embodiment, the object side surface of the second lens L2 is a paraxially convex surface, and the image side surface of the second lens L2 is a paraxially concave surface, and the second lens L2 has a positive refractive power. In other optional embodiments, the object side surface and the image side surface of the second lens L2 may be arranged in other concave-convex distribution conditions, and the second lens L2 may have a negative refractive power.

[0033] If the focal length of the second lens L2 is defined as f2, the condition 1.58≦f2 / f≦11.25 is satisfied, and the refractive power is reasonably distributed, so that the system has excellent imaging quality and low sensitivity.

[0034] If the radius of curvature of the object side surface of the second lens L2 is defined as R3 and the radius of curvature of the image side surface of the second lens L2 is defined as R4, the conditional formula -1.85≦(R3+R4) / (R3-R4)≦-0.49 is satisfied, which defines the shape of the second lens L2. Within the range defined by the conditional formula, it is possible to alleviate the degree of deflection of light rays passing through the lens, and effectively reduce aberration.

[0035] If the axial thickness of the second lens L2 is defined as d3, the conditional expression 0.01≦d3 / TTL≦0.05 is satisfied, which is advantageous for controlling the lens thickness and overall lens length.

[0036] In this embodiment, the object side surface of the third lens L3 is a paraxial concave surface, and the image side surface of the third lens L3 is a paraxial convex surface, and the third lens L3 has a positive refractive power. In other optional embodiments, the object side surface and the image side surface of the third lens L3 may be arranged in other concave-convex distribution conditions, and the third lens L3 may have a negative refractive power.

[0037] If the radius of curvature of the object side surface of the third lens L3 is defined as R5 and the radius of curvature of the image side surface of the third lens L3 is defined as R6, then the conditional formula 4.50≦(R5+R6) / (R5-R6)≦34.00 is satisfied, which defines the shape of the third lens L3. Within the range defined by the conditional formula, it is possible to reduce the degree of deflection of light passing through the lens, and effectively reduce aberration.

[0038] If the axial thickness of the third lens L3 is defined as d5, the conditional expression 0.15≦d5 / TTL≦0.17 is satisfied, which is advantageous for controlling the lens thickness and overall lens length.

[0039] In this embodiment, the object side surface of the fourth lens L4 is a paraxial convex surface, and the image side surface of the fourth lens L4 is a paraxial concave surface, and the fourth lens L4 has a negative refractive power. In other optional embodiments, the object side surface and the image side surface of the fourth lens L4 may be arranged in other concave-convex distribution conditions, and the fourth lens L4 may have a positive refractive power.

[0040] If the focal length of the fourth lens L4 is defined as f4, then the conditional formula -54.00≦f4 / f≦-2.68 is satisfied, which specifies the ratio of the focal length f4 of the fourth lens L4 to the focal length f of the system. This is advantageous for improving the performance of the optical system within the range of the conditional formula.

[0041] If the axial thickness of the fourth lens L4 is defined as d7, the conditional expression 0.02≦d7 / TTL≦0.15 is satisfied, which is advantageous for controlling the lens thickness and the overall lens length.

[0042] In this embodiment, the object side surface of the fifth lens L5 is a paraxial convex surface, and the image side surface of the fifth lens L5 is a paraxial convex surface, and the fifth lens L5 has a positive refractive power. In other optional embodiments, the object side surface and the image side surface of the fifth lens L5 may be arranged in other concave-convex distribution conditions, and the fifth lens L5 may have a negative refractive power.

[0043] If the focal length of the fifth lens L5 is defined as f5, then the conditional formula 1.80≦f5 / f≦9.03 is satisfied, which specifies the ratio of the focal length f5 of the fifth lens L5 to the focal length f of the system. This is advantageous for improving the performance of the optical system within the range of the conditional formula.

[0044] If the radius of curvature of the object side surface of the fifth lens L5 is defined as R9 and the radius of curvature of the image side surface of the fifth lens L5 is defined as R10, then the conditional expression -0.13≦(R9+R10) / (R9-R10)≦0.09 is satisfied, which defines the shape of the fifth lens L5. Within the range defined by the conditional expression, it is possible to alleviate the degree of deflection of light passing through the lens, and effectively reduce aberration.

[0045] If the axial thickness of the fifth lens L5 is defined as d9, then the conditional expression 0.05≦d9 / TTL≦0.07 is satisfied, which is advantageous for controlling the lens thickness and the overall lens length.

[0046] In this embodiment, the sixth lens L6 has a paraxially convex object side surface and a paraxially convex image side surface, and the sixth lens L6 has a positive refractive power. In other optional embodiments, the object side surface and the image side surface of the sixth lens L6 may be arranged in other concave-convex distribution conditions, and the sixth lens L6 may have a negative refractive power.

[0047] If the focal length of the sixth lens L6 is defined as f6, then the conditional formula 2.07≦f6 / f≦8.00 is satisfied, which specifies the ratio of the focal length f6 of the sixth lens L6 to the focal length f of the system. Within the range of the conditional formula, this is advantageous for improving the performance of the optical system.

[0048] If the radius of curvature of the object side surface of the sixth lens L6 is defined as R11 and the radius of curvature of the image side surface of the sixth lens L6 is defined as R12, the conditional expression -0.39≦(R11+R12) / (R11-R12)≦-0.14 is satisfied, which defines the shape of the sixth lens L6. Within the range defined by the conditional expression, it is possible to alleviate the degree of deflection of light passing through the lens, and effectively reduce aberration.

[0049] If the axial thickness of the sixth lens L6 is defined as d11, the condition 0.07≦d11 / TTL≦0.12 is satisfied, which is advantageous for controlling the lens thickness and the overall lens length.

[0050] In this embodiment, the seventh lens L7 has a paraxially concave object side surface and a paraxially concave image side surface, and the seventh lens L7 has a negative refractive power. In other alternative embodiments, the object side surface and the image side surface of the seventh lens L7 may be arranged in other concave-convex distribution situations, and the seventh lens L7 may have a positive refractive power.

[0051] If the focal length of the seventh lens L7 is defined as f7, then the conditional formula -2.09≦f7 / f≦-1.09 is satisfied, which specifies the ratio of the focal length f7 of the seventh lens L7 to the focal length f of the system. This is advantageous for improving the performance of the optical system within the range of the conditional formula.

[0052] If the radius of curvature of the object side surface of the seventh lens L7 is defined as R13 and the radius of curvature of the image side surface of the seventh lens L7 is defined as R14, then the conditional formula 0.11≦(R13+R14) / (R13-R14)≦0.38 is satisfied. This conditional formula defines the shape of the seventh lens L7, and within the range defined by the conditional formula, the degree of deflection of light passing through the lens can be mitigated, effectively reducing aberrations.

[0053] If the axial thickness of the seventh lens L7 is defined as d13, the condition 0.01≦d13 / TTL≦0.02 is satisfied, which is advantageous for controlling the lens thickness and the overall lens length.

[0054] In this embodiment, the object side surface of the eighth lens L8 is a paraxial convex surface, and the image side surface of the eighth lens L8 is a paraxial concave surface, and the eighth lens L8 has a positive refractive power. In other optional embodiments, the object side surface and the image side surface of the eighth lens L8 may be arranged in other concave-convex distribution conditions, and the eighth lens L8 may have a negative refractive power.

[0055] If the focal length of the eighth lens L8 is defined as f8, then the conditional formula -9.96≦f8 / f≦2.36 is satisfied, which specifies the ratio of the focal length f8 of the eighth lens L8 to the focal length f of the system, and is advantageous for improving the performance of the optical system within the range of the conditional formula.

[0056] If the central radius of curvature of the object side surface of the eighth lens L8 is defined as R15 and the central radius of curvature of the image side surface of the seventh lens L7 is defined as R16, then the conditional formula -0.55≦(R15+R16) / (R15-R16)≦-0.31 is satisfied. This conditional formula defines the shape of the eighth lens L8, and within the range defined by the conditional formula, the degree of deflection of light passing through the lens can be mitigated, effectively reducing aberrations.

[0057] If the axial thickness of the eighth lens L8 is defined as d15, the condition 0.02≦d15 / TTL≦0.07 is satisfied, which is advantageous for controlling the lens thickness and the overall lens length.

[0058] In this embodiment, the object side surface of the ninth lens L9 is a paraxially convex surface, and the image side surface of the ninth lens L9 is a paraxially concave surface, and the ninth lens L9 has a positive refractive power. In other optional embodiments, the object side surface and the image side surface of the ninth lens L9 may be arranged in other concave-convex distribution conditions, and the ninth lens L9 may have a negative refractive power.

[0059] If the focal length of the ninth lens L9 is defined as f9, then the conditional formula 1.77≦f9 / f≦2.31 is satisfied, which specifies the ratio of the focal length f9 of the ninth lens L9 to the focal length f of the system, and is advantageous for improving the performance of the optical system within the range of the conditional formula.

[0060] If the axial thickness of the ninth lens L9 is defined as d17, the condition 0.06≦d17 / TTL≦0.13 is satisfied, which is advantageous for controlling the lens thickness and the overall lens length.

[0061] In this embodiment, a microscope objective lens and a cylindrical mirror are used in combination, and the focal length of the cylindrical mirror is 200.00 mm.

[0062] The microscope objective lens 10 of the present invention will be described below using examples. The symbols used in each example are as follows. The focal length, axial distance, radius of curvature, and axial thickness are all in mm.

[0063] TTL: Optical length (the axial distance from the object side of the first lens L1 to the image plane) in mm.

[0064] Preferably, an inflection point and / or a stationary point may be further set on the object side and / or image side of the lens to meet the demand for high quality imaging, and a specific embodiment is given below.

[0065] Table 1 shows design data of the microscope objective lens 10 according to the first embodiment of the present invention.

[0066] [Table 1]

[0067] The meanings of the symbols are as follows: S1: Aperture R: Radius of curvature of the optical surface, or central radius of curvature in the case of a lens R1: Radius of curvature of the object side surface of the first lens L1 R2: Radius of curvature of the image side surface of the first lens L1 R3: Radius of curvature of the object side surface of the second lens L2 R4: Radius of curvature of the image side of the second lens L2 R5: Radius of curvature of the object side surface of the third lens L3 R6: Radius of curvature of the image side of the third lens L3 R7: Radius of curvature of the object side of the fourth lens L4 R8: Radius of curvature of the image side of the fourth lens L4 R9: Radius of curvature of the object side of the fifth lens L5 R10: Radius of curvature of the image side of the fifth lens L5 R11: Radius of curvature of the object side of the sixth lens L6 R12: Radius of curvature of the image side of the sixth lens L6 R13: Radius of curvature of the object side surface of the seventh lens L7 R14: Radius of curvature of the image side of the seventh lens L7 R15: Radius of curvature of the object side of the eighth lens L8 R16: Radius of curvature of the image side of the eighth lens L8 R17: Radius of curvature of the object side of the ninth lens L9 R18: Radius of curvature of the image side of the ninth lens L9 d: Axial thickness of the lens or axial distance between lenses d0: The axial distance from the aperture stop S1 to the object side of the first lens L1 d1: Axial thickness of the first lens L1 d2: The axial distance from the image side surface of the first lens L1 to the object side surface of the second lens L2 d3: Axial thickness of the second lens L2 d4: The axial distance from the image side surface of the second lens L2 to the object side surface of the third lens L3 d5: Axial thickness of the third lens L3 d6: The axial distance from the image side surface of the third lens L3 to the object side surface of the fourth lens L4 d7: Axial thickness of the fourth lens L4 d8: The axial distance from the image side surface of the fourth lens L4 to the object side surface of the fifth lens L5 d9: Axial thickness of the fifth lens L5 d10: the axial distance from the image side surface of the fifth lens L5 to the object side surface of the sixth lens L6 d11: Axial thickness of the sixth lens L6 d12: Axial distance from the image side surface of the sixth lens L6 to the object side surface of the seventh lens L7 d13: Axial thickness of the seventh lens L7 d14: Axial distance from the image side surface of the seventh lens L7 to the object side surface of the eighth lens L8 d15: Axial thickness of the eighth lens L8 d16: The axial distance from the image side surface of the eighth lens L8 to the object side surface of the ninth lens L9 d17: Axial thickness of the ninth lens L9 d18: The axial distance from the image side of the ninth lens L9 to the object side of the optical filter nd: Refractive index of d line 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 the fourth lens L4 nd5: refractive index of the d line of the fifth lens L5 nd6: Refractive index of the d line of the sixth lens L6 nd7: Refractive index of the d line of the seventh lens L7 nd8: Refractive index of the d line of the eighth lens L8 nd9: Refractive index of the d line of the ninth lens L9 vd: Abbe number v1: Abbe number of the first lens L1 v2: Abbe number of the second lens L2 v3: Abbe number of the third lens L3 v4: Abbe number of the fourth lens L4 v5: Abbe number of the fifth lens L5 v6: Abbe number of the sixth lens L6 v7: Abbe number of the seventh lens L7 v8: Abbe number of the eighth lens L8 v9: Abbe number of the ninth lens L9

[0068] Fig. 2 and Fig. 3 are schematic diagrams showing the axial chromatic aberration and the chromatic aberration of magnification after light having wavelengths of 700 nm, 656 nm, 588 nm, 520 nm, 486 nm, and 435 nm passes through the microscope objective lens 10 according to the first embodiment. Fig. 4 is a schematic diagram showing the field curvature and the distortion aberration after light having wavelength of 656 nm passes through the microscope objective lens 10 according to the first embodiment, where the field curvature S in Fig. 4 is the field curvature in the sagittal direction, and T is the field curvature in the tangential direction.

[0069] Table 4 below shows values ​​corresponding to the parameters defined by various numerical values ​​and conditional expressions in each of the first, second and third embodiments.

[0070] As shown in Table 4, the first embodiment satisfies each of the conditional expressions.

[0071] In this embodiment, the microscope objective lens has an entrance pupil diameter of 12.6 mm, a full field of view image height of 1.5 mm, a diagonal field angle of 8.62°, an object-side numerical aperture NA of 0.30, a magnification of 10x, and an operating band of 486 nm to 700 nm, and has good optical performance.

[0072] Second embodiment The second embodiment is basically the same as the first embodiment, and the symbols have the same meanings as in the first embodiment, so only the differences will be described below.

[0073] In this embodiment, the image side surface of the second lens L2 is paraxially convex, and the eighth lens L8 has negative refractive power.

[0074] Table 2 shows design data of the microscope objective lens 20 according to the second embodiment of the present invention.

[0075] [Table 2]

[0076] Fig. 6 and Fig. 7 are schematic diagrams showing the axial chromatic aberration and the chromatic aberration of magnification of light having wavelengths of 700 nm, 656 nm, 588 nm, 520 nm, 486 nm, and 435 nm after passing through the microscope objective lens 20 according to the second embodiment. Fig. 8 is a schematic diagram showing the field curvature and the distortion aberration of light having a wavelength of 656 nm after passing through the microscope objective lens 20 according to the second embodiment, where the field curvature S in Fig. 8 is the field curvature in the sagittal direction, and T is the field curvature in the tangential direction.

[0077] Table 4 below shows values ​​corresponding to the parameters defined by various numerical values ​​and conditional expressions in each of the first, second and third embodiments.

[0078] As shown in Table 4, the second embodiment satisfies each of the conditional expressions.

[0079] In this embodiment, the microscope objective lens has an entrance pupil diameter of 8 mm, a full field of view image height of 1.5 mm, a diagonal field angle of 8.22°, an object-side numerical aperture NA of 0.19, a magnification of 10x, and an operating band of 486 nm to 700 nm, and has good optical performance.

[0080] Third embodiment The third embodiment is basically the same as the first embodiment, and the symbols have the same meanings as in the first embodiment, so only the differences will be described below.

[0081] In this embodiment, the object side surface of the fourth lens L4 is paraxially concave, and the eighth lens L8 has negative refractive power.

[0082] Table 3 shows design data of the microscope objective lens 30 according to the third embodiment of the present invention.

[0083] [Table 3]

[0084] Fig. 10 and Fig. 11 are schematic diagrams showing the axial chromatic aberration and the chromatic aberration of magnification of light having wavelengths of 700 nm, 656 nm, 588 nm, 520 nm, 486 nm, and 435 nm after passing through the microscope objective lens 30 according to the third embodiment. Fig. 12 is a schematic diagram showing the field curvature and the distortion aberration of light having a wavelength of 656 nm after passing through the microscope objective lens 30 according to the third embodiment, where the field curvature S in Fig. 12 is the field curvature in the sagittal direction, and T is the field curvature in the tangential direction.

[0085] Table 4 below shows values ​​corresponding to the parameters defined by various numerical values ​​and conditional expressions in each of the first, second and third embodiments.

[0086] As shown in Table 4, the third embodiment satisfies each of the conditional expressions.

[0087] In this embodiment, the microscope objective lens has an entrance pupil diameter of 16 mm, a full field of view image height of 1.5 mm, a diagonal field angle of 8.22°, an object-side numerical aperture NA of 0.38, a magnification of 10x, and an operating band of 486 nm to 700 nm, and has good optical performance.

[0088] [Table 4]

[0089] Here, f12 is the composite focal length of the first lens and the second lens.

[0090] The above is merely an embodiment of the present invention, and those skilled in the art may make modifications without departing from the spirit of the present invention, and all such modifications fall within the scope of protection of the present invention.

Claims

1. 1. A microscope objective lens, comprising: The optical system is constituted by, in order from the object side to the image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens, an objective lens for a microscope, characterized in that the following conditional expressions (1) to (4) are satisfied when a distance from the object-side surface of the first lens to an object to be observed is WD, an optical length of the objective lens for a microscope is TTL, an object-side numerical aperture of the objective lens for a microscope is NA, a focal length of the objective lens for a microscope is f, an equivalent focal length of the sixth lens, the seventh lens, and the eighth lens is f678, a focal length of the ninth lens is f9, a radius of curvature of the object-side surface of the ninth lens is R17, and a radius of curvature of the image-side surface of the ninth lens is R18. 0.19≦WD / TTL≦0.36 (1) 4.00≦NA*f≦8.00 (2) 7.00≦f678 / f9≦16.00 (3) -10.00≦(R17+R18) / (R17-R18)≦-1.50 (4)

2. 2. The microscope objective lens according to claim 1, wherein the following conditional expression (5) is satisfied, where n2 is the refractive index of the second lens: n2≧2.00 (5)

3. 2. The microscope objective lens according to claim 1, wherein the following conditional expression (6) is satisfied when the focal length of the third lens is f3: 3.00≦f3 / f≦6.00 (6)

4. the first lens has negative refractive power, an object side surface of the first lens is a paraxially concave surface, and an image side surface of the first lens is a paraxially concave surface; 2. The microscope objective lens according to claim 1, characterized in that, when the focal length of the first lens is f1, the radius of curvature of the object-side surface of the first lens is R1, the radius of curvature of the image-side surface of the first lens is R2, and the axial thickness of the first lens is d1, the following conditional expressions (7) to (9) are satisfied. -2.20≦f1 / f≦-0.70 (7) -0.42≦(R1+R2) / (R1-R2)≦-0.16 (8) 0.01≦d1 / TTL≦0.02 (9)

5. the second lens has a positive refractive power, and an object side surface of the second lens is a convex surface on a paraxial line; The objective lens for a microscope according to claim 1, characterized in that, when the focal length of the second lens is f2, the radius of curvature of the object-side surface of the second lens is R3, the radius of curvature of the image-side surface of the second lens is R4, and the axial thickness of the second lens is d3, the objective lens for a microscope satisfies the following conditional expressions (10) to (12). 1.58≦f2 / f≦11.25 (10) -1.85≦(R3+R4) / (R3-R4)≦-0.49 (11) 0.01≦d3 / TTL≦0.05 (12)

6. the third lens has positive refractive power, an object side surface of the third lens is a concave surface in a paraxial direction, and an image side surface of the third lens is a convex surface in the paraxial direction; 2. The microscope objective lens according to claim 1, characterized in that, when the radius of curvature of the object side surface of the third lens is R5, the radius of curvature of the image side surface of the third lens is R6, and the axial thickness of the third lens is d5, the following conditional expressions (13) and (14) are satisfied. 4.50≦(R5+R6) / (R5-R6)≦34.00 (13) 0.15≦d5 / TTL≦0.17 (14)

7. the fourth lens has a negative refractive power, and an image side surface of the fourth lens is a concave surface in a paraxial direction; 2. The microscope objective lens according to claim 1, characterized in that, when the focal length of the fourth lens is f4 and the axial thickness of the fourth lens is d7, the following conditional expressions (15) and (16) are satisfied. −54.00≦f4 / f≦−2.68 (15) 0.02≦d7 / TTL≦0.15 (16)

8. the fifth lens has positive refractive power, an object side surface of the fifth lens is a convex surface in a paraxial direction, and an image side surface of the fifth lens is a convex surface in a paraxial direction; The objective lens for a microscope according to claim 1, characterized in that, when the focal length of the fifth lens is f5, the radius of curvature of the object-side surface of the fifth lens is R9, the radius of curvature of the image-side surface of the fifth lens is R10, and the axial thickness of the fifth lens is d9, the following conditional expressions (17) to (19) are satisfied. 1.80≦f5 / f≦9.03 (17) -0.13≦(R9+R10) / (R9-R10)≦0.09 (18) 0.05≦d9 / TTL≦0.07 (19)

9. the sixth lens has positive refractive power, an object side surface of the sixth lens is a convex surface on a paraxial line, and an image side surface of the sixth lens is a convex surface on a paraxial line, The objective lens for a microscope according to claim 1, characterized in that, when the focal length of the sixth lens is f6, the radius of curvature of the object side surface of the sixth lens is R11, the radius of curvature of the image side surface of the sixth lens is R12, and the axial thickness of the sixth lens is d11, the following conditional expressions (20) to (22) are satisfied. 2.07≦f6 / f≦8.00 (20) -0.39≦(R11+R12) / (R11-R12)≦-0.14 (21) 0.07≦d11 / TTL≦0.12 (22)

10. the seventh lens has negative refractive power, an object side surface of the seventh lens is a paraxial concave surface, and an image side surface of the seventh lens is a paraxial concave surface; The objective lens for a microscope according to claim 1, characterized in that, when the focal length of the seventh lens is f7, the radius of curvature of the object side surface of the seventh lens is R13, the radius of curvature of the image side surface of the seventh lens is R14, and the axial thickness of the seventh lens is d13, the following conditional expressions (23) to (25) are satisfied. −2.09≦f7 / f≦−1.09 (23) 0.11≦(R13+R14) / (R13-R14)≦0.38 (24) 0.01≦d13 / TTL≦0.02 (25)

11. an object side surface of the eighth lens is a paraxially convex surface, and an image side surface of the eighth lens is a paraxially convex surface, The objective lens for a microscope according to claim 1, characterized in that, when the focal length of the eighth lens is f8, the central radius of curvature of the object side surface of the eighth lens is R15, the central radius of curvature of the image side surface of the eighth lens is R16, and the axial thickness of the eighth lens is d15, the following conditional expressions (26) to (28) are satisfied. −9.96≦f8 / f≦2.36 (26) -0.55≦(R15+R16) / (R15-R16)≦-0.31 (27) 0.02≦d15 / TTL≦0.07 (28)

12. the ninth lens has positive refractive power, an object side surface of the ninth lens is a convex surface in a paraxial direction, and an image side surface of the ninth lens is a concave surface in a paraxial direction; 2. The microscope objective lens according to claim 1, characterized in that, when the focal length of the ninth lens is f9 and the axial thickness of the eighth lens is d17, the following conditional expressions (29) and (30) are satisfied. 1.77≦f9 / f≦2.31 (29) 0.06≦d17 / TTL≦0.13 (30)

13. 2. The microscope objective lens according to claim 1, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens are all made of glass.

Images