Microscope objective lens

Abstract

The present invention discloses an objective lens for a microscope. The objective lens for the microscope has a focal length of f, an optical length of TTL, an image height of IH, a combined focal length of the first and second lenses of f1_2, a focal length of the third lens of f3, a combined focal length of the 14th, 15th, and 16th lenses of f14_15_16, a combined focal length of the 17th and 18th lenses of f17_18, an on-axis thickness of the 17th lens of d33, an on-axis thickness of the 18th lens of d35, and satisfies the following relationship. The objective lens for a microscope according to the present invention has a compact lens, excellent optical properties, low distortion, a magnification of 20x, and a long working distance. -3.10 ≤ f1_2 / f3 ≤ -1.80 3.40 ≤ f14_15_16 / f ≤ 7.00 4.00≦f17_18 / (d33+d35)≦120.00 0.08 ≤ IH*f / TTL ≤ 0.09

Description

Technical Field

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

Background Art

[0002] In recent years, the demand for microscope lenses has been increasing. However, due to the limitations of the optical structure, conventional microscope lenses have distortion aberration within the microscopic range. On the other hand, since a microscope lens is composed of multiple lenses, it affects the length of the lens. Also, when the structure of the microscope lens becomes long, the working distance becomes short. Furthermore, since the magnification is affected by the working distance, it is disadvantageous for the operator to use.

[0003] With the development of technology and the diversification of user needs, the requirements of scientific research for the observation quality of microscope lenses are increasing, and there is an urgent need for microscope lenses with excellent optical characteristics, less distortion aberration, high magnification, and long working distance.

Summary of the Invention

[0004] In view of the above problems, an object of the present invention is to provide an objective lens for a microscope having a large aperture number, a compact lens structure, and good optical characteristics.

[0005] To solve the above technical problems, the present invention provides an objective lens for a microscope, and the objective lens for a microscope is sequentially provided with a first lens, a second lens, a third lens having a negative refractive power, a fourth lens, a fifth lens, a sixth lens, a seventh lens having a positive refractive power, an eighth lens, a ninth lens, a tenth lens having a positive refractive power, an eleventh lens, a twelfth lens, a thirteenth lens having a positive refractive power, a fourteenth lens, a fifteenth lens, a sixteenth lens, a seventeenth lens, and an eighteenth lens from the exit side to the object side, The focal length of the microscope objective lens is f, the combined focal length of the first and second lenses is f1_2, the focal length of the third lens is f3, the combined focal length of the 14th, 15th, and 16th lenses is f14_15_16, the combined focal length of the 17th and 18th lenses is f17_18, the on-axis thickness of the 17th lens is d33, the on-axis thickness of the 18th lens is d35, the on-axis distance from the object plane of the microscope objective lens to the exit side of the first lens is TTL, and the image height of the microscope objective lens is IH. -3.10 ≤ f1_2 / f3 ≤ -1.80 3.40 ≤ f14_15_16 / f ≤ 7.00 4.00≦f17_18 / (d33+d35)≦120.00 0.08 ≤ IH*f / TTL ≤ 0.09 The above relationship is satisfied.

[0006] Preferably, the radius of curvature of the exit side of the 10th lens is R19, the radius of curvature of the object side of the 10th lens is R20, and the relationship expressed as -1.60 ≤ R19 / R20 ≤ -2.50 is satisfied.

[0007] Preferably, the optical axial distance from the object surface of the microscope objective lens to the object side surface of the 18th lens is WD, the numerical aperture of the microscope objective lens is NA, and the relationship expressed as WD*NA≧1.10 is satisfied.

[0008] Preferably, the portion of the first lens's exit side near the optical axis is convex, the portion of the first lens's object side near the optical axis is convex, the radius of curvature of the first lens's exit side is R1, the radius of curvature of the first lens's object side is R2, and the thickness of the first lens along the optical axis is d1. -1.39≦(R1+R2) / (R1-R2)≦-0.24 0.03 ≤ d1 / TTL ≤ 0.10 The above relationship is satisfied.

[0009] Preferably, the portion of the second lens's exit side near the optical axis is concave, the portion of the second lens's object side near the optical axis is concave, the radius of curvature of the second lens's exit side is R3, the radius of curvature of the second lens's object side is R4, and the thickness of the second lens along the optical axis is d3. 0.15 ≤ (R3 + R4) / (R3 - R4) ≤ 1.13 0.01 ≤ d3 / TTL ≤ 0.06 The above relationship is satisfied.

[0010] Preferably, a composite lens having a positive refractive power is formed by bonding the object side of the first lens and the output side of the second lens, satisfying the relation expressed as 1.93 ≤ f1_2 / f ≤ 8.42.

[0011] Preferably, the portion of the third lens near the optical axis on the side of the object is concave, the radius of curvature of the exit side of the third lens is R5, the radius of curvature of the side of the object is R6, and the thickness of the third lens along the optical axis is d5. 0.15 ≤ (R5 + R6) / (R5 - R6) ≤ 1.57 0.01 ≤ d5 / TTL ≤ 0.03 -4.19 ≤ f3 / f ≤ -1.24 The above relationship is satisfied.

[0012] Preferably, the portion of the fourth lens's exit side near the optical axis is concave, the radius of curvature of the fourth lens's exit side is R7, the radius of curvature of the fourth lens's object side is R8, and the thickness of the fourth lens along the optical axis is d7. -2.94≦(R7+R8) / (R7-R8)≦-0.12 0.01 ≤ d7 / TTL ≤ 0.06 The above relationship is satisfied.

[0013] Preferably, the portion of the fifth lens near the optical axis on the object side is convex, 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, and the thickness of the fifth lens along the optical axis is d9. 0.11≦(R9+R10) / (R9-R10)≦2.20 0.04 ≤ d9 / TTL ≤ 0.15 The above relationship is satisfied.

[0014] Preferably, the portion of the sixth lens's exit side near the optical axis is concave, the portion of the sixth lens's object side near the optical axis is convex, the radius of curvature of the sixth lens's exit side is R11, the radius of curvature of the sixth lens's object side is R12, and the thickness of the sixth lens along the optical axis is d11. -10.75≦(R11+R12) / (R11-R12)≦-2.17 0.01 ≤ d11 / TTL ≤ 0.03 The above relationship is satisfied.

[0015] Preferably, the object side of the fourth lens and the output side of the fifth lens are bonded together, and the object side of the fifth lens and the output side of the sixth lens are bonded together, thereby forming a composite lens having negative refractive power. The combined focal length of the fourth lens, the fifth lens, and the sixth lens is f4_5_6, and satisfies the relationship expressed as -7.70 ≤ f4_5_6 / f ≤ -1.41.

[0016] Preferably, the portion of the seventh lens closest to the optical axis on the object side is convex, 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 thickness of the seventh lens on the optical axis is d13, and the focal length of the seventh lens is f7. 0.41≦(R13+R14) / (R13-R14)≦2.60 0.02 ≤ d13 / TTL ≤ 0.09 2.16 ≤ f7 / f ≤ 7.34 The above relationship is satisfied.

[0017] Preferably, a portion of the exit side surface of the eighth lens close to the optical axis is a convex surface, a portion of the object side surface of the eighth lens close to the optical axis is a convex surface, 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, and the on-axis thickness of the eighth lens is d15. 0.19 ≦ (R15 + R16) / (R15 - R16) ≦ 1.15 0.05 ≦ d15 / TTL ≦ 0.16 The above relational expressions are satisfied.

[0018] Preferably, a portion of the exit side surface of the ninth lens close to the optical axis is a concave surface, a portion of the object side surface of the ninth lens close to the optical axis is a convex surface, 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. -5.69 ≦ (R17 + R18) / (R17 - R18) ≦ -0.82 0.01 ≦ d17 / TTL ≦ 0.04 The above relational expressions are satisfied.

[0019] Preferably, a positive refractive power synthetic lens is formed by bonding the object side surface of the eighth lens and the exit side surface of the ninth lens, and the synthetic focal length of the eighth lens and the ninth lens is f8_9, satisfying the relational expression represented by 4.08 ≦ f8_9 / f ≦ 84.​​​​​​​​​​​​

[0021] Preferably, the portion of the 11th lens near the optical axis on the exit side is convex, the portion of the 11th lens near the optical axis on the object side is convex, the radius of curvature of the 11th lens near the optical axis is R21, the radius of curvature of the 11th lens near the object side is R22, and the thickness of the 11th lens along the optical axis is d21. 0.02≦(R21+R22) / (R21-R22)≦1.02 0.03 ≤ d21 / TTL ≤ 0.13 The above relationship is satisfied.

[0022] Preferably, the portion of the 12th lens's exit side near the optical axis is concave, the radius of curvature of the 12th lens's exit side is R23, the radius of curvature of the 12th lens's object side is R24, and the thickness of the 12th lens along the optical axis is d23. -2.18≦(R23+R24) / (R23-R24)≦-0.29 0.01 ≤ d23 / TTL ≤ 0.04 The above relationship is satisfied.

[0023] Preferably, a composite lens having negative refractive power is formed by bonding the object side of the 11th lens and the output side of the 12th lens, and the combined focal length of the 11th lens and the 12th lens is f11_12, satisfying the relationship expressed as -879.88 ≤ f11_12 / f ≤ -5.21.

[0024] Preferably, the portion of the 13th lens's exit side near the optical axis is convex, the radius of curvature of the 13th lens's exit side is R25, the radius of curvature of the 13th lens's object side is R26, the thickness of the 13th lens along the optical axis is d25, and the focal length of the 13th lens is f13. -3.04≦(R25+R26) / (R25-R26)≦-0.53 0.03 ≤ d25 / TTL ≤ 0.10 1.68 ≤ f13 / f ≤ 7.42 The above relationship is satisfied.

[0025] Preferably, the portion of the 14th lens near the optical axis on the exit side is convex, the portion of the 14th lens near the optical axis on the object side is convex, the radius of curvature of the 14th lens near the optical axis is R27, the radius of curvature of the 14th lens near the object side is R28, and the thickness of the 14th lens along the optical axis is d27. -1.06≦(R27+R28) / (R27-R28)≦-0.27 0.04 ≤ d27 / TTL ≤ 0.13 The above relationship is satisfied.

[0026] Preferably, the portion of the 15th lens near the optical axis on the exit side is concave, the portion of the 15th lens near the optical axis on the object side is concave, the radius of curvature of the 15th lens near the optical axis is R29, the radius of curvature of the 15th lens near the object side is R30, and the thickness of the 15th lens along the optical axis is d29. -0.05≦(R29+R30) / (R29-R30)≦0.98 0.01 ≤ d29 / TTL ≤ 0.03 The above relationship is satisfied.

[0027] Preferably, the portion of the 16th lens near the optical axis on the exit side is convex, the portion of the 16th lens near the optical axis on the object side is convex, the radius of curvature of the 16th lens near the optical axis is R31, the radius of curvature of the 16th lens near the object side is R32, and the thickness of the 16th lens along the optical axis is d31. -1.45≦(R31+R32) / (R31-R32)≦-0.29 0.02 ≤ d31 / TTL ≤ 0.09 The above relationship is satisfied.

[0028] Preferably, a composite lens having positive refractive power is constructed by bonding the object side of the 14th lens to the output side of the 15th lens, and bonding the object side of the 15th lens to the output side of the 16th lens.

[0029] Preferably, the portion of the 17th lens near the optical axis on the exit side is convex, the portion of the 17th lens near the optical axis on the object side is convex, the radius of curvature of the 17th lens near the optical axis is R33, the radius of curvature of the 17th lens near the object side is R34, and the thickness of the 17th lens along the optical axis is d33. -1.08≦(R33+R34) / (R33-R34)≦-0.17 0.02 ≤ d33 / TTL ≤ 0.08 The above relationship is satisfied.

[0030] Preferably, the portion of the 18th lens near the optical axis on the exit side is concave, the portion of the 18th lens near the optical axis on the object side is concave, the radius of curvature of the 18th lens near the optical axis is R35, the radius of curvature of the 18th lens near the object side is R36, and the thickness of the 18th lens along the optical axis is d35. 0.25≦(R35+R36) / (R35-R36)≦0.93 0.01 ≤ d35 / TTL ≤ 0.04 The above relationship is satisfied.

[0031] Preferably, a composite lens having a positive refractive power is formed by bonding the object side of the 17th lens and the output side of the 18th lens, satisfying the relation expressed as 1.30 ≤ f17_18 / f ≤ 81.29. [Effects of the Invention]

[0032] The beneficial effects of the present invention are as follows: By arranging the lenses as described above, the flow of light rays between the lenses can be controlled, which is advantageous for the smooth transition of the emitted light rays. Furthermore, because the lens structure is compact, the total optical length of the lens can be controlled when the imaging range reaches the desired state. As a result, the objective lens for the microscope can have a large numerical aperture, ensure sufficient light-gathering ability, and possess excellent optical properties, meeting the design needs of low distortion, 20x magnification, and a long working distance. [Brief explanation of the drawing]

[0033] One or more embodiments are described illustratively with reference to the drawings. These illustrative descriptions are not limiting to the embodiments. Parts having similar reference numerals in the drawings are analogous. Unless otherwise specified, the size of the drawings is not limiting to the scale.

[0034] [Figure 1] This is a schematic diagram of the configuration of a microscope objective lens according to the first embodiment of the present invention. [Figure 2] Figure 1 is a schematic diagram of the field curvature and distortion of a microscope objective lens. [Figure 3] Figure 1 is a schematic diagram of the chromatic aberration of magnification in a microscope objective lens. [Figure 4] Figure 1 is a schematic diagram of chromatic aberration along the optical axis of a microscope objective lens. [Figure 5] This is a schematic diagram of the configuration of a microscope objective lens according to a second embodiment of the present invention. [Figure 6] Figure 5 is a schematic diagram of the field curvature and distortion of a microscope objective lens. [Figure 7] Figure 5 is a schematic diagram of the chromatic aberration of magnification in a microscope objective lens. [Figure 8] Figure 5 is a schematic diagram of chromatic aberration along the optical axis of a microscope objective lens. [Figure 9] This is a schematic diagram of the configuration of a microscope objective lens according to the third embodiment of the present invention. [Figure 10] Figure 9 is a schematic diagram of the field curvature and distortion of a microscope objective lens. [Figure 11] Figure 9 is a schematic diagram of the chromatic aberration of magnification in a microscope objective lens. [Figure 12] Figure 9 is a schematic diagram of chromatic aberration along the optical axis of a microscope objective lens. [Figure 13] This is a schematic diagram of the configuration of a microscope objective lens according to the fourth embodiment of the present invention. [Figure 14] Figure 13 is a schematic diagram of the field curvature and distortion of a microscope objective lens. [Figure 15]Figure 13 is a schematic diagram of the chromatic aberration of magnification in a microscope objective lens. [Figure 16] Figure 13 is a schematic diagram of chromatic aberration along the optical axis of a microscope objective lens. [Modes for carrying out the invention]

[0035] To further clarify the object, technical solution, and advantages 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, in each embodiment of the present invention, many technical details are presented so that the present invention may be more easily understood by those skilled in the art. However, the technical solution for which the present invention seeks protection can be realized without these technical details or the various changes and modifications based on the following embodiments.

[0036] In embodiments of the present invention, directions or positional relationships indicated by terms such as "up," "down," "left," "right," "front," "back," "top," "bottom," "inside," "outside," "center," "vertical," "horizontal," "lateral," and "vertical" are based on the directions or positional relationships shown in the drawings. These terms are primarily for the purpose of better describing the present invention and its embodiments, and do not limit the indicated devices, elements, or components to having a specific direction or being constructed or operated in a specific direction.

[0037] Furthermore, some of the above terms may have meanings other than indicating direction or positional relationships. For example, the term "above" may, depending on the context, indicate some kind of dependency or connection. Those skilled in the art will be able to understand the specific meaning of these terms in this invention depending on the specific situation.

[0038] Furthermore, the terms “attach,” “install,” “set up,” “open,” “connect,” and “link” should be understood in a broad sense. For example, they may be fixed connections, removable connections or integrated structures, mechanical connections or electrical connections, direct connections or indirect connections via an intermediate medium, or internal communication between two devices, elements, or components. Those skilled in the art will be able to understand the specific meaning of these terms in the present invention depending on the specific circumstances.

[0039] Furthermore, terms such as "first," "second," etc., are primarily used to distinguish between different devices, elements, or components (the specific type and structure may be the same or different), and are not used to explicitly or implicitly indicate the relative importance or number of the devices, elements, or components being referred to. Unless otherwise specified, "plural" means two or more.

[0040] As shown in Figures 1, 5, 9, and 13, the present invention provides microscope objective lenses 10, 20, 30, and 40. The microscope objective lenses 10, 20, 30, and 40 are arranged sequentially from the output side to the object side and consist of a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6 having negative refractive power, a seventh lens L7, an eighth lens L8, a ninth lens L9 having positive refractive power, a tenth lens L10, an eleventh lens L11, a twelfth lens L12 having positive refractive power, a thirteenth lens L13, a fourteenth lens L14, a fifteenth lens L15, a sixteenth lens L16, a seventeenth lens L17, and an eighteenth lens L18 having positive refractive power.

[0041] The focal lengths of the microscope objective lenses 10, 20, 30, and 40 are f, the combined focal length of the first lens L1 and the second lens L2 is f1_2, the focal length of the third lens L3 is f3, the 14th lens is L14, the combined focal length of the 15th lens L15 and the 16th lens L16 is f14_15_16, the combined focal length of the 17th lens L17 and the 18th lens L18 is f17_18, the on-axis thickness of the 17th lens L17 is d33, the on-axis thickness of the 18th lens L18 is d35, the on-axis distance from the object plane of the microscope objective lens 10 to the exit side of the first lens L1 is TTL, that is, the total optical length is TTL, the image height of the microscope objective lens 10 is IH, and the following relationship is satisfied. -3.10 ≤ f1_2 / f3 ≤ -1.80 (1) 3.40 ≤ f 14 15 16 / f ≤ 7.00 (2) 4.00≦f17_18 / (d33+d35)≦120.00 (3) 0.08 ≤ IH*f / TTL ≤ 0.09 (4)

[0042] Here, relation (1) specifies the ratio of the combined focal length f1_2 of the composite lens composed of the first lens L1 and the second lens L2 to the focal length f3 of the third lens L3. Within the range of relation (1), it is advantageous to control the flow of light rays between the lenses, and the lens structure of the microscope objective lenses 10, 20, 30, and 40 can be made compact.

[0043] In relation (2), the ratio of the combined focal length f14_15_16 of the object-side composite lens of the microscope objective lenses 10, 20, 30, and 40, which are composed of the 14th lens L14, the 15th lens L15, and the 16th lens L16, to the focal length f of the microscope objective lenses 10, 20, 30, and 40 is defined. Within the range of relation (2), sufficient light-gathering capability can be achieved.

[0044] In relation (3), the range of the ratio between the focal length and thickness of the composite lens composed of the 17th lens L17 and the 18th lens L18 is defined. Within the range of relation (3), the composite lens has sufficient refractive power and a reasonable thickness.

[0045] In relation (4), the range of the ratio between the product of the image height IH and focal length f of the microscope objective lenses 10, 20, 30, and 40 and their optical length TTL is defined. Within the range of relation (4), the optical length of the microscope objective lenses 10, 20, 30, and 40 can be controlled when the imaging range reaches a desired state.

[0046] In this embodiment, by arranging the lenses as described above, the flow of light rays between the lenses can be controlled, which is advantageous for the smooth transition of the emitted light rays. Furthermore, because the lens structure is compact, the total optical length of the lens can be controlled when the imaging range reaches the desired state. As a result, the microscope objective lens has a large numerical aperture, ensures sufficient light-gathering ability, and possesses excellent optical characteristics, low distortion, high magnification, and a long working distance.

[0047] The units for focal length, thickness, image height, and total optical length are in mm.

[0048] Preferably, the radius of curvature of the exit side of the 10th lens is R19, and the radius of curvature of the object side of the 10th lens is R20, satisfying the following relationship. -1.60 ≤ R19 / R20 ≤ -2.50 (5)

[0049] In relation (5), the shape of the 10th lens L10 is defined. This is advantageous for the smooth transition of the emitted light rays and can improve the image quality.

[0050] Preferably, the distance on the optical axis from the object surface of the microscope objective lens to the object side surface of the 18th lens is WD, that is, the working distance is WD, the numerical aperture of the microscope objective lens is NA, and the following relationship is satisfied. WD*NA≧1.10 (6)

[0051] In relational equation (6), the range of the product of the working distance WD and numerical aperture NA of the microscope objective lenses 10, 20, 30, and 40 is defined. By defining an 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 good aberration performance and high resolution. Furthermore, by defining a lower limit of the above product, it is possible to avoid the working distance WD being too short, eliminating the need for the user to be aware of collisions between the objective lens and the object being observed, and improving work efficiency during measurement. In particular, when observing with microscope objective lenses, it is common to observe objects with rough surfaces using objective lenses with low numerical apertures. The present invention ensures that objective lenses with low numerical apertures have a sufficient working distance by defining a lower limit of WD*NA. Therefore, even if the object being observed has a rough surface, it can be measured, achieving high versatility for microscope objective lenses. In other words, within the range of relational equation (6), the microscope objective lenses have sufficient resolution, high work efficiency and high versatility.

[0052] In one embodiment, the portion of the first lens L1 near the optical axis on the exit side is convex, and the portion of the object side near the optical axis is also convex. In another embodiment, the object side and the exit side of the first lens L1 may be provided with other uneven surface distributions.

[0053] Preferably, the radius of curvature of the exit side of the first lens is R1, the radius of curvature of the object side of the first lens is R2, the thickness of the first lens on the optical axis is d1, and the following relationship is satisfied. -1.39≦(R1+R2) / (R1-R2)≦-0.24 (7) 0.03 ≤ d1 / TTL ≤ 0.10 (8)

[0054] In relation (7), the shape of the first lens L1 is defined. By rationally controlling the shape of the first lens L1, the degree of polarization when light rays pass through the first lens L1 can be mitigated, and aberrations can be effectively reduced. More preferably, the relation expressed as -0.87 ≤ (R1 + R2) / (R1 - R2) ≤ -0.30 is satisfied. In relation (8), the range of the ratio of the on-axis thickness d1 of the first lens L1 to the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 is defined. Within the range of this relation, it is advantageous to control the thickness of the first lens L1, and the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be further controlled. More preferably, the relation expressed as 0.05 ≤ d1 / TTL ≤ 0.08 is satisfied.

[0055] In one embodiment, the portion of the second lens L2 near the optical axis on the exit side is concave, and the portion of the second lens L2 near the optical axis on the object side is concave. In another embodiment, the object side and the exit side of the second lens L2 may be provided with other uneven surface distributions.

[0056] Preferably, 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 thickness of the second lens along the optical axis is d3, and the following relationship is satisfied. 0.15≦(R3+R4) / (R3-R4)≦1.13 (9) 0.01 ≤ d3 / TTL ≤ 0.06 (10)

[0057] In relation (9), the shape of the second lens is defined. Within the range of relation (9), the second lens L2 can effectively correct the spherical aberration of the system. More preferably, the relation expressed as 0.23 ≤ (R3 + R4) / (R3 - R4) ≤ 0.90 is satisfied. In relation (10), the range of the ratio of the on-axis thickness d3 of the second lens L2 to the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 is defined. Within the range of this relation, the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be reasonably controlled. More preferably, the relation expressed as 0.01 ≤ d3 / TTL ≤ 0.05 is satisfied.

[0058] Preferably, a composite lens having positive refractive power is formed by bonding the object side of the first lens L1 and the output side of the second lens L2, satisfying the following relationship. 1.93 ≤ f1_2 / f ≤ 8.42 (11)

[0059] In one embodiment, the portion of the third lens L3 near the optical axis on the exit side is concave or convex, and the portion of the object side near the optical axis is concave. In another embodiment, the object side of the third lens L3 may be convex.

[0060] Preferably, the radius of curvature of the exit side surface of the third lens L3 is R5, the radius of curvature of the side surface of the object is R6, the thickness of the third lens on the optical axis is d5, and the following relationship is satisfied. 0.15≦(R5+R6) / (R5-R6)≦1.57 (12) 0.01 ≤ d5 / TTL ≤ 0.03 (13) -4.19≦f3 / f≦-1.24 (14)

[0061] In relation (12), the shape of the third lens L3 is defined. Within the range of this relation, the aberrations of the microscope objective lenses 10, 20, 30, and 40 are reduced. More preferably, the relation expressed as 0.24 ≤ (R5 + R6) / (R5 - R6) ≤ 1.25 is satisfied. In relation (13), the range of the ratio of the on-axis thickness d15 of the third lens L3 to the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 is defined. Within the range of this relation, the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be controlled. More preferably, the relation expressed as 0.01 ≤ d5 / TTL ≤ 0.02 is satisfied. In relation (14), 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 is defined. Within the range of this relation, aberrations are effectively reduced and image quality is improved. More preferably, the relation expressed as -2.62 ≤ f3 / f ≤ -1.55 is satisfied.

[0062] In one embodiment, the portion of the fourth lens L4's exit side near the optical axis is concave, and the portion of the object's side near the optical axis is either concave or convex. In another embodiment, the exit side of the fourth lens L4 may be convex.

[0063] Preferably, the radius of curvature of the exit side of the fourth lens L4 is R7, the radius of curvature of the object side of the fourth lens L4 is R8, the thickness of the fourth lens L4 on the optical axis is d7, and the following relationship is satisfied. -2.94≦(R7+R8) / (R7-R8)≦-0.12 (15) 0.01 ≤ d7 / TTL ≤ 0.06 (16)

[0064] In relation (15), the shape of the fourth lens L4 is defined. This allows the fourth lens L4 to effectively correct the spherical aberration of the system. More preferably, the relation expressed as -1.84 ≤ (R7 + R8) / (R7 - R8) ≤ -0.15 is satisfied. In relation (16), the range of the ratio between the on-axial thickness d7 of the fourth lens L4 and the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 is defined. Within the range of this relation, it is advantageous for controlling the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40. More preferably, the relation expressed as 0.01 ≤ d7 / TTL ≤ 0.05 is satisfied.

[0065] In one embodiment, the portion of the fifth lens L5 near the optical axis on the exit side is convex or concave, and the portion of the object side near the optical axis is convex. In another embodiment, the object side of the fifth lens L5 may be concave.

[0066] Preferably, the radius of curvature of the exit side surface of the fifth lens L5 is R9, the radius of curvature of the object side surface of the fifth lens L5 is R10, the thickness of the fifth lens on the optical axis is d9, and the following relationship is satisfied. 0.11≦(R9+R10) / (R9-R10)≦2.20 (17) 0.04 ≤ d9 / TTL ≤ 0.15 (18)

[0067] In relation (17), the fifth lens L5 is defined. Within the range of this relation, the spherical aberration of the microscope objective lenses 10, 20, 30, and 40 is reduced, and the image quality is improved. More preferably, the relation expressed as 0.18 ≤ (R9 + R10) / (R9 - R10) ≤ 1.76 is satisfied. In relation (18), the range of the ratio of the on-axis thickness d9 of the fifth lens d9 to the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 is defined. Within the range of relation (18), the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be rationally controlled. More preferably, the relation expressed as 0.06 ≤ d9 / TTL ≤ 0.12 is satisfied.

[0068] In one embodiment, the portion of the sixth lens L6 near the optical axis on the exit side is concave, and the portion of the sixth lens L6 near the optical axis on the object side is convex. In another embodiment, the object side and the exit side of the sixth lens L6 may be provided with other uneven surface distributions.

[0069] Preferably, the radius of curvature of the exit side surface of the sixth lens L6 is R11, the radius of curvature of the object side surface of the sixth lens L6 is R12, the thickness of the sixth lens L6 on the optical axis is d11, and the following relationship is satisfied. -10.75≦(R11+R12) / (R11-R12)≦-2.17 (19) 0.01 ≤ d11 / TTL ≤ 0.03 (20)

[0070] In relation (19), the shape of the sixth lens L6 is defined. This allows for rational control of the shape of the sixth lens L6, and effectively corrects aberrations of the off-axis angle of view, etc. More preferably, the relation expressed as -6.72 ≤ (R11 + R12) / (R11 - R12) ≤ -2.71 is satisfied. In relation (20), the on-axis thickness d11 of the sixth lens L6 is defined. Within the range of relation (20), the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be effectively controlled. More preferably, the relation expressed as 0.02 ≤ d11 / TTL ≤ 0.03 is satisfied.

[0071] Preferably, the object side of the fourth lens L4 and the output side of the fifth lens L5 are bonded together, and the object side of the fifth lens L5 and the output side of the sixth lens L6 are bonded together to form a composite lens having negative refractive power. The combined focal length of the fourth lens L4, the fifth lens L5, and the sixth lens L6 is f4_5_6, and satisfies the following relationship. -7.70 ≤ f₄₅₶ / f ≤ -1.41 (21)

[0072] In relation (21), the range of the ratio between the combined focal length of the composite lens composed of the fourth lens L4, the fifth lens L5, and the sixth lens L6 and the focal length f of the microscope objective lenses 10, 20, 30, and 40 is defined. Within this range, the optical properties of the microscope objective lenses 10, 20, 30, and 40 are improved. More preferably, the relation expressed as -4.81 ≤ f4_5_6 / f ≤ -1.77 is satisfied.

[0073] In one embodiment, the portion of the seventh lens L7 closest to the optical axis on the exit side is concave or convex, and the portion of the object side closest to the optical axis is convex. In another embodiment, the object side of the seventh lens L7 may be concave.

[0074] Preferably, the radius of curvature of the exit side of the seventh lens L7 is R13, the radius of curvature of the object side of the seventh lens L7 is R14, the thickness of the seventh lens L7 on the optical axis is d13, the focal length of the seventh lens L7 is f7, and the following relationship is satisfied. 0.41≦(R13+R14) / (R13-R14)≦2.60 (22) 0.02 ≤ d13 / TTL ≤ 0.09 (23) 2.16 ≤ f7 / f ≤ 7.34 (24)

[0075] In relation (22), the shape of the seventh lens L7 is defined. Within the range of this relation, the seventh lens L7 can effectively correct the spherical aberration of the system and improve the image quality. More preferably, the relation expressed as 0.66 ≤ (R13 + R14) / (R13 - R14) ≤ 2.08 is satisfied. In relation (23), the on-optical axial thickness d13 of the seventh lens L7 is defined. Within the range of this relation, the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be shortened. More preferably, the relation expressed as 0.04 ≤ d13 / TTL ≤ 0.07 is satisfied. In relation (24), the ratio of the focal length f7 of the seventh lens L7 to the focal length f of the microscope objective lenses 10, 20, 30, and 40 is defined. Within the range of this relation, aberrations are reduced and image quality is improved. More preferably, the relationship expressed as 3.46 ≤ f7 / f ≤ 5.87 is satisfied.

[0076] In one embodiment, the portion of the output side of the eighth lens L8 closest to the optical axis is convex, and the portion of the object side of the eighth lens L8 closest to the optical axis is convex. In another embodiment, the object side and the output side of the eighth lens L8 may be provided with other uneven surface distributions.

[0077] Preferably, the radius of curvature of the exit side of the eighth lens L8 is R15, the radius of curvature of the object side of the eighth lens L8 is R16, the thickness of the eighth lens L8 on the optical axis is d15, and the following relationship is satisfied. 0.19≦(R15+R16) / (R15-R16)≦1.15 (25) 0.05 ≤ d15 / TTL ≤ 0.16 (26)

[0078] In relation (25), the shape of the eighth lens L8 is defined. Within the range of this relation, the degree of deflection when light rays pass through the eighth lens L8 can be mitigated, and aberrations can be effectively reduced. More preferably, the relation expressed as 0.30 ≤ (R15 + R16) / (R15 - R16) ≤ 0.92 is satisfied. In relation (26), the on-optical-axis thickness d15 of the eighth lens L8 is defined. Within the range of this relation, the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be shortened. More preferably, the relation expressed as 0.08 ≤ d15 / TTL ≤ 0.13 is satisfied.

[0079] In one embodiment, the portion of the ninth lens L9 near the optical axis on the exit side is concave, and the portion of the object side near the optical axis on the object side is convex. In another embodiment, the object side and the exit side of the ninth lens L9 may be provided with other uneven surface distributions.

[0080] Preferably, the radius of curvature of the exit side of the ninth lens L9 is R17, the radius of curvature of the object side of the ninth lens L9 is R18, the thickness of the ninth lens L9 on the optical axis is d17, and the following relationship is satisfied. -5.69≦(R17+R18) / (R17-R18)≦-0.82 (27) 0.01 ≤ d17 / TTL ≤ 0.04 (28)

[0081] In relation (27), the shape of the ninth lens L9 is defined. Within the range of this relation, the optical properties of the microscope objective lenses 10, 20, 30, and 40 are improved. More preferably, the relation expressed as -3.56 ≤ (R17 + R18) / (R17 - R18) ≤ -1.02 is satisfied. In relation (28), the ratio of the thickness d17 of the ninth lens L9 to the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 is defined. Within the range of this relation, the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be rationally controlled. More preferably, the relation expressed as 0.02 ≤ d17 / TTL ≤ 0.03 is satisfied.

[0082] Preferably, a composite lens having positive refractive power is formed by bonding the object side of the eighth lens L8 and the output side of the ninth lens L9. The combined focal length of the eighth lens L8 and the ninth lens L9 is f8_9, and satisfies the following relationship. 4.08 ≤ f8_9 / f ≤ 84.27 (29)

[0083] In relation (29), the ratio of the focal length f8_9 of the composite lens composed of the eighth lens L8 and the ninth lens L9 to the focal length f of the microscope objective lenses 10, 20, 30, and 40 is defined. This improves the optical characteristics of the microscope objective lenses 10, 20, 30, and 40. More preferably, the relation expressed as 6.53 ≤ f8_9 / f ≤ 67.42 is satisfied.

[0084] In one embodiment, the portion of the exit side of the 10th lens L10 closest to the optical axis is convex, and the portion of the object side of the 10th lens L10 closest to the optical axis is convex. In another embodiment, the object side and the exit side of the 10th lens L10 may be provided with other uneven surface distributions.

[0085] Preferably, the radius of curvature of the exit side of the 10th lens L10 is R19, the radius of curvature of the object side of the 10th lens L10 is R20, the thickness of the 10th lens on the optical axis is d19, the focal length of the 10th lens is f10, and the following relationship is satisfied. -1.10≦(R19+R20) / (R19-R20)≦0.31 (30) 0.03 ≤ d19 / TTL ≤ 0.11 (31) 2.38 ≤ f10 / f ≤ 12.26 (32)

[0086] In relation (30), the shape of the 10th lens L10 is defined. Within the range of this relation, the degree of deflection when light rays pass through the 10th lens L10 can be mitigated, and aberrations can be effectively reduced. More preferably, the relation expressed as -0.69 ≤ (R19 + R20) / (R19 - R20) ≤ 0.25 is satisfied. In relation (31), the on-axial thickness d19 of the 10th lens L10 is defined. Within the range of this relation, the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be shortened. More preferably, the relation expressed as 0.06 ≤ d19 / TTL ≤ 0.12 is satisfied. In relation (32), the range of the ratio of the focal length of the 10th lens L10 to the focal length f of the microscope objective lenses 10, 20, 30, and 40 is defined. This reduces aberrations and improves image quality. More preferably, the relationship expressed as 3.81 ≤ f10 / f ≤ 9.81 is satisfied.

[0087] In one embodiment, the portion of the 11th lens L11 closest to the optical axis on the exit side is convex, and the portion of the 11th lens L11 closest to the optical axis on the object side is also convex. In another embodiment, the object side and the exit side of the 10th lens L10 may be provided with other uneven surface distributions.

[0088] Preferably, the radius of curvature of the exit side of the 11th lens L11 is R21, the radius of curvature of the object side of the 11th lens L11 is R22, the thickness of the 11th lens L11 on the optical axis is d21, and the following relationship is satisfied. 0.02≦(R21+R22) / (R21-R22)≦1.02 (33) 0.03 ≤ d21 / TTL ≤ 0.13 (34)

[0089] In relation (33), the shape of the 11th lens L11 is defined. Within the range of this relation, the degree of deflection when light rays pass through the 11th lens L11 can be mitigated, and aberrations can be effectively reduced. More preferably, the relation expressed as 0.04 ≤ (R21 + R22) / (R21 - R22) ≤ 0.81 is satisfied. In relation (34), the on-optical-axis thickness d21 of the 11th lens L11 is defined. Within the range of this relation, the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be shortened, and the structure of the microscope objective lenses 10, 20, 30, and 40 can be made more compact. More preferably, the relation expressed as 0.04 ≤ d21 / TTL ≤ 0.11 is satisfied.

[0090] In one embodiment, the portion of the 12th lens L12 near the optical axis on the exit side is concave, and the portion of the 12th lens L12 near the optical axis on the object side is concave or convex. In another embodiment, the exit side of the 12th lens L12 may be convex.

[0091] Preferably, the radius of curvature of the exit side of the 12th lens L12 is R23, the radius of curvature of the object side of the 12th lens L12 is R24, the thickness of the 12th lens L12 on the optical axis is d23, and the following relationship is satisfied. -2.18≦(R23+R24) / (R23-R24)≦-0.29 (35) 0.01 ≤ d23 / TTL ≤ 0.04 (36)

[0092] In relation (35), the shape of the 12th lens L12 is defined. Within the range of this relation, the 12th lens L12 can effectively correct the spherical aberration of the system. More preferably, the relation expressed as -1.37 ≤ (R23 + R24) / (R23 - R24) ≤ -0.36 is satisfied. In relation (36), the on-optical axial thickness d23 of the 12th lens L12 is defined. Within the range of this relation, the total optical length TTL of the microscope objective lens 10 can be shortened. More preferably, the relation expressed as 0.02 ≤ d23 / TTL ≤ 0.03 is satisfied.

[0093] Preferably, a composite lens having negative refractive power is formed by bonding the object side of the 11th lens L11 and the output side of the 12th lens L12. The combined focal length of the 11th lens L11 and the 12th lens L12 is f11_12, and satisfies the following relationship. -879.88 ≤ f11_12 / f ≤ -5.21 (37)

[0094] In relation (37), the range of the ratio between the combined focal length f11_12 of the composite lens composed of the 11th lens L11 and the 12th lens L12 and the focal length f of the microscope objective lenses 10, 20, 30, and 40 is defined. The optical properties of the microscope objective lenses 10, 20, 30, and 40 are improved. More preferably, the relation expressed as -549.93 ≤ f11_12 / f ≤ -6.51 is satisfied.

[0095] In one embodiment, the portion of the 13th lens L13 closest to the optical axis on the exit side is convex, and the portion of the 13th lens L13 closest to the optical axis on the object side is concave or convex. In another embodiment, the exit side of the 13th lens L13 may be concave.

[0096] 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 thickness of the 13th lens L13 on the optical axis is d25, and the focal length of the 13th lens L13 is f13, satisfying the following relationship. -3.04≦(R25+R26) / (R25-R26)≦-0.53 (38) 0.03 ≤ d25 / TTL ≤ 0.10 (39) 1.68 ≤ f13 / f ≤ 7.42 (40)

[0097] In relation (38), the shape of the 13th lens L13 is defined. Within the range of this relation, the spherical aberration of the microscope objective lenses 10, 20, 30, and 40 is reduced. More preferably, the relation expressed as -1.90 ≤ (R25 + R26) / (R25 - R26) ≤ -0.66 is satisfied. In relation (39), the on-optical axial thickness d25 of the 13th lens L13 is defined. Within the range of this relation, the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be effectively shortened. More preferably, the relation expressed as 0.05 ≤ d25 / TTL ≤ 0.08 is satisfied. In relation (40), the range of the ratio of the focal length f13 of the 13th lens L13 to the focal length f of the microscope objective lenses 10, 20, 30, and 40 is defined. This reduces aberration and improves image quality. More preferably, the relationship expressed as 2.69 ≤ f13 / f ≤ 5.93 is satisfied.

[0098] In one embodiment, the portion of the 14th lens L14 near the optical axis on the exit side is convex, and the portion of the 14th lens L14 near the optical axis on the object side is also convex. In another embodiment, the exit side and the object side of the 14th lens L14 may be provided with other uneven surface distributions.

[0099] Preferably, the radius of curvature of the exit side of the 14th lens L14 is R27, the radius of curvature of the object side of the 14th lens L14 is R28, the thickness of the 14th lens L14 on the optical axis is d27, and the following relationship is satisfied. -1.06≦(R27+R28) / (R27-R28)≦-0.27 (41) 0.04 ≤ d27 / TTL ≤ 0.13 (42)

[0100] In relation (41), the shape of the 14th lens L14 is defined. Within the range of this relation, the 14th lens L14 can effectively correct the spherical aberration of the system. More preferably, the relation expressed as -0.66 ≤ (R27 + R28) / (R27 - R28) ≤ -0.34 is satisfied. In relation (42), the on-axis thickness d27 of the 14th lens L14 is defined. The total optical length TTL of the 10, 20, 30, and 40 objective lenses for the microscope can be shortened. More preferably, the relation expressed as 0.07 ≤ d27 / TTL ≤ 0.10 is satisfied.

[0101] In one embodiment, the portion of the 15th lens L15 near the optical axis on the exit side is concave, and the portion of the 15th lens L15 near the optical axis on the object side is concave. In another embodiment, the exit side and the object side of the 15th lens L15 may be provided with other uneven surface distributions.

[0102] Preferably, the radius of curvature of the exit side of the 15th lens L15 is R29, the radius of curvature of the object side of the 15th lens L15 is R30, the thickness of the 15th lens L15 on the optical axis is d29, and the following relationship is satisfied. -0.05≦(R29+R30) / (R29-R30)≦0.98 (43) 0.01 ≤ d29 / TTL ≤ 0.03 (44)

[0103] In relation (43), the shape of the 15th lens L15 is defined. Within the range of this relation, the degree of deflection when light rays pass through the 15th lens L15 can be mitigated, and aberrations can be effectively reduced. More preferably, the relation expressed as -0.03 ≤ (R29 + R30) / (R29 - R30) ≤ 0.79 is satisfied. In relation (44), the on-axis thickness d29 of the 15th lens L15 is defined. The total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be shortened. More preferably, the relation expressed as 0.01 ≤ d29 / TTL ≤ 0.02 is satisfied.

[0104] In one embodiment, the portion of the 16th lens L16 near the optical axis on the exit side is convex, and the portion of the 16th lens L16 near the optical axis on the object side is also convex. In another embodiment, the exit side and the object side of the 16th lens L16 may be provided with other uneven surface distributions.

[0105] Preferably, the radius of curvature of the exit side of the 16th lens L16 is R31, the radius of curvature of the object side of the 16th lens L16 is R32, the thickness of the 16th lens L16 along the optical axis is d31, and the following relationship is satisfied. -1.45≦(R31+R32) / (R31-R32)≦-0.29 (45) 0.02 ≤ d31 / TTL ≤ 0.09 (46)

[0106] In relation (45), the shape of the 16th lens L16 is defined. Within the range of this relation, the degree of polarization when light rays pass through the 16th lens L16 can be mitigated, and aberrations can be effectively reduced. More preferably, the relation expressed as -0.91 ≤ (R31 + R32) / (R31 - R32) ≤ -0.36 is satisfied. In relation (46), the on-optical-axis thickness d31 of the 16th lens L16 is defined. Within the range of this relation, the optical characteristics of the microscope objective lenses 10, 20, 30, and 40 are improved. More preferably, the relation expressed as 0.03 ≤ d31 / TTL ≤ 0.07 is satisfied.

[0107] In one embodiment, a composite lens having positive refractive power is constructed by bonding the object side of the 14th lens L14 to the output side of the 15th lens L15, and bonding the object side of the 15th lens L15 to the output side of the 16th lens L16.

[0108] In one embodiment, the portion of the 17th lens L17 closest to the optical axis on the exit side is convex, and the portion of the 17th lens L17 closest to the optical axis on the object side is also convex. In another embodiment, the exit side and the object side of the 17th lens L17 may be provided with other uneven surface distributions.

[0109] Preferably, the radius of curvature of the exit side of the 17th lens L17 is R33, the radius of curvature of the object side of the 17th lens L17 is R34, the thickness of the 17th lens L17 on the optical axis is d33, and the following relationship is satisfied. -1.08≦(R33+R34) / (R33-R34)≦-0.17 (47) 0.02 ≤ d33 / TTL ≤ 0.08 (48)

[0110] In relation (47), the shape of the 17th lens L17 is defined. Within the range of this relation, the optical characteristics and image quality of the microscope objective lens 10 are improved. More preferably, the relation expressed as -0.67 ≤ (R33 + R34) / (R33 - R34) ≤ -0.22 is satisfied. In relation (48), the range of the ratio between the on-axis thickness d33 of the 17th lens L17 and the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 is defined. The total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be controlled. More preferably, the relation expressed as 0.04 ≤ d33 / TTL ≤ 0.06 is satisfied.

[0111] In one embodiment, the portion of the 18 lens L18 near the optical axis on the exit side is concave, and the portion of the 18 lens L18 near the optical axis on the object side is concave. In another embodiment, the exit side and the object side of the 18 lens L18 may be provided with other uneven surface distributions.

[0112] Preferably, the radius of curvature of the exit side of the 18th lens L18 is R35, the radius of curvature of the object side of the 18th lens L18 is R36, the thickness of the 18th lens L18 on the optical axis is d35, and the following relationship is satisfied. 0.25≦(R35+R36) / (R35-R36)≦0.93 (49) 0.01 ≤ d35 / TTL ≤ 0.04 (50)

[0113] In relation (49), the shape of the 18th lens L18 is defined. Within the range of this relation, the degree of polarization when light rays pass through the 18th lens L18 can be mitigated, and aberrations can be effectively reduced. More preferably, the relation expressed as 0.40 ≤ (R35 + R36) / (R35 - R36) ≤ 0.74 is satisfied. In relation (50), the on-axis thickness d35 of the 18th lens L18 is defined. Within the range of this relation, the total optical length TTL of the microscope objective lenses 10, 20, 30, and 40 can be shortened. More preferably, the relation expressed as 0.01 ≤ d35 / TTL ≤ 0.03 is satisfied.

[0114] In this embodiment, a composite lens having positive refractive power is constructed by bonding the exit side of the 17th lens L17 and the object side of the 18th lens L18. The combined focal length f17_18 of the composite lens satisfies the following relationship. 1.30 ≤ f17_18 / f ≤ 81.29 (51)

[0115] Within the range of relation (51), the optical properties of the microscope objective lenses 10, 20, 30, and 40 are improved. More preferably, the relation expressed as 2.08 ≤ f17_18 / f ≤ 65.03 is satisfied.

[0116] In this embodiment, an optical element such as an optical filter GF is provided on the object side of the 18 lens L18. Here, the filter GF may be a glass plate or other optical filter. As shown in Figure 1, in other embodiments, the optical filter GF may be provided at a different position.

[0117] The microscope objective lenses 10, 20, 30, and 40 according to the present invention can control the flow of light rays between the lenses. Furthermore, because the lens structure is compact, the total optical length of the lens can be controlled while ensuring that the imaging range reaches the desired range. As a result, the microscope objective lenses have a large numerical aperture, sufficient light-gathering ability, excellent optical characteristics, low distortion, a magnification of 20x, and a long working distance.

[0118] The microscope objective lens 10 according to the present invention will be described below using examples. The reference numerals for each example are shown in Table 1. The units for focal length, distance on the optical axis, radius of curvature, thickness on the optical axis, inflection point position, and stationary point position are in mm.

[0119] TTL: Total optical length (the distance along the optical axis from the side of the object to the image plane of the first lens L1), in mm.

[0120] First Embodiment The part of the first lens L1 closest to the optical axis on the exit side is convex, and the part of the object's side closest to the optical axis is also convex. The area of ​​the second lens L2 closest to the optical axis on the exit side is concave, and the area of ​​the object closest to the optical axis is also concave. The third lens L3 has negative refractive power, and the part of its exit side near the optical axis is concave, as is the part of its side near the optical axis of the object. The area of ​​the fourth lens L4 closest to the optical axis on the exit side is concave, and the area of ​​the object closest to the optical axis is also concave. The part of the fifth lens L5 closest to the optical axis on the exit side is convex, and the part of the object closest to the optical axis is also convex. The part of the sixth lens L6 closest to the optical axis on the exit side is concave, while the part of the object side closest to the optical axis is convex. Lens L7, the seventh lens, has positive refractive power, and the part of its exit side near the optical axis is convex, as is the part of its side near the optical axis of the object. The part of the eighth lens L8 closest to the optical axis on the exit side is convex, and the part of the object's side closest to the optical axis is also convex. The part of the ninth lens (L9) closest to the optical axis on the exit side is concave, while the part of the object side closest to the optical axis is convex. The tenth lens L10 has a positive refractive power, and the part of its exit side near the optical axis is convex, as is the part of its side near the optical axis of the object. The part of the 11th lens L11 closest to the optical axis on the exit side is convex, and the part of the object side closest to the optical axis is also convex. The area of ​​the 12th lens L12 closest to the optical axis on the exit side is concave, and the area of ​​the object side closest to the optical axis is also concave. Lens L13 has positive refractive power, and the part of its exit side closest to the optical axis is convex, while the part of its side closest to the optical axis is concave. The part of the 14th lens L14 closest to the optical axis on the exit side is convex, and the part of the object side closest to the optical axis is also convex. The part of lens L15 closest to the optical axis on the exit side is concave, and the part of the object's side closest to the optical axis is also concave. The part of lens L16 closest to the optical axis on the exit side is convex, and the part of the object side closest to the optical axis is also convex. The part of lens L17 closest to the optical axis on the exit side is convex, and the part of the object side closest to the optical axis is also convex. The part of the 18th lens L18 closest to the optical axis on the exit side is concave, and the part of the object side closest to the optical axis is also concave.

[0121] Figure 1 is a schematic diagram of the configuration of the microscope objective lens 10 according to the first embodiment. The following shows the design data of the microscope objective lens 10 in the first embodiment of the present invention.

[0122] Table 1 lists the radius of curvature R of the output side and object side of the first lens L1 to the 18th lens L18 of the microscope objective lens 10 in the first embodiment of the present invention, the optical axis thickness of the lens, the optical axis 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).

[0123] [Table 1]

[0124] The meanings of each symbol in the table above are as follows: R: Refers to the radius of curvature of the optical surface; in the case of a lens, it is 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) R29: Radius of curvature of the exit side of lens L15 (No. 15) R30: Radius of curvature of the object side of lens L15 (15th lens) R31: Radius of curvature of the exit side of lens L16 (No. 16) R32: Radius of curvature of the object side of lens L16 (16th lens) R33: Radius of curvature of the exit side of lens L17 (No. 17) R34: Radius of curvature of the object side of lens L17 (lens number 17) R35: Radius of curvature of the exit side of lens L18 (No. 18) R36: Radius of curvature of the object side of lens L18 (No. 18) d: Optical axial thickness of the lens, optical axial distance between lenses d1: Optical axis thickness of the first lens L1 d2: Distance on the optical axis from the exit side of the first lens L1 to the object side of the second lens L2. d3: On-axis thickness of the second lens L2 d4: On-axis distance from the exit side of the second lens L2 to the object side of the third lens L3. d5: On-axis 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: On-axis thickness of the 4th 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: On-axis 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: On-axis 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: On-axis thickness of lens L7 (7th lens) d141: On-axis distance from the exit side of the 7th lens L7 to the aperture ST d142: Distance on the optical axis from aperture ST to the side of the object of lens L8 (8th lens) d15: On-axis 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: On-axis 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: On-axis 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: Optical axis 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: On-axis thickness of lens L12 (lens 12) d24: On-axis distance from the exit side of the 12th lens L12 to the object side of the 13th lens L13. d25: On-axis thickness of lens L13 (13th lens) d26: On-axis distance from the exit side of lens 13 L13 to the object side of lens 14 L14 d27: On-axis thickness of lens L14 (14th lens) d28: On-axis distance from the exit side of lens 14 L14 to the object side of lens 15 L15 d29: Distance on the optical axis of lens L15 (number 15) d30: On-axis distance from the exit side of lens 15 L15 to the object side of lens 16 L16. d31: On-axis thickness of lens L16 (16th lens) d32: On-axis distance from the exit side of lens 16 L16 to the object side of lens 17 L17 d33: On-axis thickness of lens L17 (lens 17) d34: On-axis distance from the exit side of lens 17 L17 to the object side of lens 18 L18. d35: On-axis thickness of lens L18 (lens number 18) d36: On-axis distance from the exit side of lens L18 to the object plane nd: Refractive index of the d line (the d line is green light with a wavelength of 555 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) nd15: Refractive index of the d line of lens L15 (lens number 15) nd16: Refractive index of the d line of lens L16 (lens number 16) nd17: Refractive index of the d line of lens L17 (lens number 17) nd18: Refractive index of the d line of lens L18 (lens number 18) 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) vd15: Abbe number of lens L15 (15th lens) vd16: Abbe number of lens L16 (lens number 16) vd17: Abbe number of lens L17 (lens number 17) vd18: Abbe number of lens L18 (number 18)

[0125] Furthermore, Table 5, described later, shows the various parameters in the first embodiment and the values ​​corresponding to the parameters defined by the relational formulas.

[0126] Figure 2 is a schematic diagram of field curvature and distortion after light with a wavelength of 588 nm passes through the microscope objective lens 10 according to the first embodiment. In Figure 2, the field curvature S is the sagittal field curvature, and T is the meridional field curvature. Figure 3 is a schematic diagram of chromatic aberration after light with wavelengths of 500 nm, 588 nm, 685 nm, 770 nm, and 830 nm passes through the microscope objective lens 10 according to the first embodiment. Figure 4 is a schematic diagram of chromatic aberration on the optical axis after light with wavelengths of 500 nm, 588 nm, 685 nm, 770 nm, and 830 nm passes through the microscope objective lens 10 according to the first embodiment.

[0127] As shown in Table 5, the first embodiment satisfies each of the relational expressions.

[0128] In this embodiment, the entrance pupil diameter of the microscope objective lens 10 is 15.202 mm, the image height of the entire field of view is 0.65 mm, the working distance WD is 1.38 mm, and the numerical aperture NA is 0.85. The microscope objective lens 10 can control the flow of light rays between the lenses, which is advantageous for smooth transitions of the emitted light rays. Furthermore, because the lens structure is compact, the overall length of the lens 10 can be controlled while ensuring the desired imaging range. As a result, the microscope objective lens 10 can have a large numerical aperture, ensure sufficient light-gathering ability, and possess excellent optical characteristics, meeting the design needs of low distortion, 20x magnification, and a long working distance.

[0129] Second Embodiment Figure 5 is a schematic diagram of the configuration of the microscope objective lens 20 according to the second embodiment. The second embodiment is substantially 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 will be shown below.

[0130] Table 2 shows the design data for the microscope objective lens 20 according to the second embodiment of the present invention.

[0131] [Table 2]

[0132] Furthermore, Table 5, described later, shows the values ​​corresponding to the parameters defined in the second embodiment and the relational formulas.

[0133] Figure 6 is a schematic diagram of field curvature and distortion after light with a wavelength of 588 nm passes through the objective lens 20 for a microscope according to the second embodiment. In Figure 6, the field curvature S is the sagittal field curvature, and T is the meridional field curvature. Figure 7 is a schematic diagram of chromatic aberration after light with wavelengths of 500 nm, 588 nm, 685 nm, 770 nm, and 830 nm passes through the objective lens 20 for a microscope according to the second embodiment. Figure 8 is a schematic diagram of chromatic aberration on the optical axis after light with wavelengths of 500 nm, 588 nm, 685 nm, 770 nm, and 830 nm passes through the objective lens 20 for a microscope according to the second embodiment.

[0134] As shown in Table 5, the second embodiment satisfies each of the relational expressions.

[0135] In this embodiment, the entrance pupil diameter of the microscope objective lens 20 is 15.211 mm, the image height of the entire field of view is 0.65 mm, the working distance WD is 1.30 mm, and the numerical aperture NA is 0.85. The microscope objective lens 20 can control the flow of light rays between the lenses, which is advantageous for the smooth transition of the emitted light rays. Furthermore, because the lens structure is compact, the overall length of the controlled microscope objective lens 20 can be controlled while ensuring the desired imaging range. As a result, the microscope objective lens 20 can have a large numerical aperture, ensure sufficient light-gathering ability, and possess excellent optical characteristics, meeting the design needs of low distortion, 20x magnification, and a long working distance.

[0136] Third Embodiment Figure 9 is a schematic diagram of the configuration of the microscope objective lens 30 according to the third embodiment. The third embodiment is substantially 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 will be shown below.

[0137] In this embodiment, the portion of the third lens L3 closest to the optical axis on the output side is convex. The part of the fourth lens L4 closest to the optical axis on the side of the object is convex. The area of ​​the fifth lens (L5) near the optical axis on the exit side is concave. The area of ​​the seventh lens, L7, near the optical axis on the exit side, is concave. The part of the 12th lens L12 closest to the optical axis on the side of the object is convex. The part of the 13th lens L13 closest to the optical axis on the side of the object is convex.

[0138] Table 3 shows the design data for the microscope objective lens 30 according to the third embodiment of the present invention.

[0139] [Table 3]

[0140] Furthermore, Table 5, described later, shows the various parameters in the third embodiment and the values ​​corresponding to the parameters defined by the relational formulas.

[0141] Figure 10 is a schematic diagram of 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. In Figure 10, the field curvature 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 of chromatic aberration after light with wavelengths of 500 nm, 588 nm, 685 nm, 770 nm, and 830 nm passes through the objective lens 30 for a microscope according to the third embodiment. Figure 12 is a schematic diagram of chromatic aberration on the optical axis after light with wavelengths of 500 nm, 588 nm, 685 nm, 770 nm, and 830 nm passes through the objective lens 30 for a microscope according to the third embodiment.

[0142] As shown in Table 5, the third embodiment satisfies each of the relational expressions.

[0143] In this embodiment, the entrance pupil diameter of the microscope objective lens 30 is 15.301 mm, the image height of the entire field of view is 0.65 mm, the working distance WD is 1.30 mm, and the numerical aperture NA is 0.85. The microscope objective lens 30 can control the flow of light rays between the lenses, which is advantageous for the smooth transition of the emitted light rays. Furthermore, because the lens structure is compact, the overall length of the controlled microscope objective lens 30 can be controlled while ensuring the desired imaging range. As a result, the microscope objective lens 30 can have a large numerical aperture, ensure sufficient light-gathering ability, and possess excellent optical characteristics, meeting the design needs of low distortion, 20x magnification, and a long working distance.

[0144] Fourth Embodiment Figure 13 is a schematic diagram of the configuration of the microscope objective lens 40 according to the fourth embodiment. The fourth embodiment is substantially 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 will be shown below.

[0145] In this embodiment, the portion of the fourth lens L4 closest to the optical axis on the side of the object is convex. The area of ​​the fifth lens (L5) near the optical axis on the exit side is concave. The area of ​​the seventh lens, L7, near the optical axis on the exit side, is concave. The part of the 13th lens L13 closest to the optical axis on the side of the object is convex.

[0146] Table 4 shows the design data for the microscope objective lens 40 according to the fourth embodiment of the present invention.

[0147] [Table 4]

[0148] Furthermore, Table 5, described later, shows the various parameters in the fourth embodiment and the values ​​corresponding to the parameters defined by the relational formulas.

[0149] Figure 14 is a schematic diagram of 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. In Figure 14, the field curvature 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 of chromatic aberration after light with wavelengths of 500 nm, 588 nm, 685 nm, 770 nm, and 830 nm passes through the objective lens 40 for a microscope according to the fourth embodiment. Figure 16 is a schematic diagram of chromatic aberration on the optical axis after light with wavelengths of 500 nm, 588 nm, 685 nm, 770 nm, and 830 nm passes through the objective lens 40 for a microscope according to the fourth embodiment.

[0150] As shown in Table 5, the fourth embodiment satisfies each of the relational expressions.

[0151] In this embodiment, the entrance pupil diameter of the microscope objective lens 40 is 15.302 mm, the image height of the entire field of view is 0.65 mm, the working distance WD is 1.30 mm, and the numerical aperture NA is 0.85. The microscope objective lens 40 can control the flow of light rays between the lenses, which is advantageous for smooth transitions of the emitted light rays. Furthermore, because the lens structure is compact, the overall length of the controlled microscope objective lens 40 can be controlled while ensuring the desired imaging range. As a result, the microscope objective lens 40 can have a large numerical aperture, ensure sufficient light-gathering ability, and satisfy the design needs of excellent optical characteristics, low distortion, 20x magnification, and a long working distance.

[0152] Table 5 shows the values ​​corresponding to each relation in the comparative embodiment, according to the relation formulas described above.

[0153] [Table 5]

[0154] The above describes in detail the objective lenses for microscopes according to each embodiment of the present invention. In this invention, the principle and embodiments of the invention have been explained using specific examples, but these embodiments are for understanding the technical idea of ​​the present invention, and since the specific embodiments and scope of application may change, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A microscope objective lens comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens having negative refractive power, a seventh lens, an eighth lens, a ninth lens having positive refractive power, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens, a fifteenth lens, a sixteenth lens, a seventeenth lens, and an eighteenth lens, which are arranged sequentially from the output side to the object side. The focal length of the aforementioned microscope objective lens is f. The combined focal length of the first lens and the second lens is f1_2. The focal length of the third lens is f3. The combined focal length of the 14th lens, the 15th lens, and the 16th lens is f14_15_16. The combined focal length of the 17th lens and the 18th lens is f17_18. The optical axis thickness of the 17th lens is d33. The optical axis thickness of the 18th lens is d35. The optical axis distance from the object surface of the microscope objective lens to the exit side of the first lens is TTL. The image height of the aforementioned microscope objective lens is IH. -3.10 ≤ f1_2 / f3 ≤ -1.80 3.40 ≤ f14_15_16 / f ≤ 7.00 4.00≦f17_18 / (d33+d35)≦120.00 0.08≦IH*f / TTL≦0.09 The above relationship satisfies A microscope objective lens characterized by the following features.

2. The radius of curvature of the exit side of the tenth lens is R19. The radius of curvature of the object side surface of the tenth lens is R20. -1.60 ≤ R19 / R20 ≤ -2.50 The above relationship satisfies The microscope objective lens according to feature 1.

3. The optical axis distance from the object surface of the microscope objective lens to the object side surface of the 18th lens is WD, and the numerical aperture of the microscope objective lens is NA. WD*NA≧1.10 The above relationship satisfies The microscope objective lens according to feature 1.

4. The part of the first lens's output side closest to the optical axis is convex, The portion of the first lens closest to the optical axis on the side of the object is convex, The radius of curvature of the exit side of the first lens is R1. The radius of curvature of the object side of the first lens is R2. The optical axis thickness of the first lens is d1, -1.39≦(R1+R2) / (R1-R2)≦-0.24 0.03 ≤ d1 / TTL ≤ 0.10 The above relationship satisfies The microscope objective lens according to feature 1.

5. The part of the second lens's output side closest to the optical axis is concave. The portion of the second lens closest to the optical axis on the side of the object is concave. 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 optical axis thickness of the second lens is d3. 0.15≦(R3+R4) / (R3-R4)≦1.13 0.01 ≤ d3 / TTL ≤ 0.06 The above relationship satisfies The microscope objective lens according to feature 1.

6. A composite lens having positive refractive power is formed by bonding the object side of the first lens and the output side of the second lens together. 1.93 ≤ f1_2 / f ≤ 8.42 The above relationship satisfies The microscope objective lens according to feature 1.

7. The portion of the third lens closest to the optical axis on the side of the object is concave. The radius of curvature of the exit side of the third lens is R5, and the radius of curvature of the object side is R6. The optical axis thickness of the third lens is d5. 0.15≦(R5+R6) / (R5-R6)≦1.57 0.01 ≤ d5 / TTL ≤ 0.03 -4.19 ≤ f³ / f ≤ -1.24 The above relationship satisfies The microscope objective lens according to feature 1.

8. The portion of the fourth lens's output side closest to the optical axis is concave. 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 optical axis thickness of the fourth lens is d7. -2.94≦(R7+R8) / (R7-R8)≦-0.12 0.01 ≤ d7 / TTL ≤ 0.06 The above relationship satisfies The microscope objective lens according to feature 1.

9. The portion of the fifth lens closest to the optical axis on the side of the object is convex, 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 optical axis thickness of the fifth lens is d9. 0.11≦(R9+R10) / (R9-R10)≦2.20 0.04 ≤ d9 / TTL ≤ 0.15 The above relationship satisfies The microscope objective lens according to feature 1.

10. The portion of the sixth lens's output side closest to the optical axis is concave. The portion of the sixth lens closest to the optical axis on the side of the object is convex, 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 optical axis thickness of the sixth lens is d11. -10.75≦(R11+R12) / (R11-R12)≦-2.17 0.01 ≤ d11 / TTL ≤ 0.03 The above relationship satisfies The microscope objective lens according to feature 1.

11. A composite lens having negative refractive power is formed by bonding the object side of the fourth lens to the output side of the fifth lens, and bonding the object side of the fifth lens to the output side of the sixth lens. The combined focal length of the fourth lens, the fifth lens, and the sixth lens is f4_5_6. -7.70 ≤ f4_5_6 / f ≤ -1.41 The above relationship satisfies The microscope objective lens according to feature 1.

12. The portion of the seventh lens closest to the optical axis on the side of the object is convex, 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 optical axis thickness of the seventh lens is d13. The focal length of the seventh lens is f7. 0.41≦(R13+R14) / (R13-R14)≦2.60 0.02 ≤ d13 / TTL ≤ 0.09 2.16 ≤ f7 / f ≤ 7.34 The above relationship satisfies The microscope objective lens according to feature 1.

13. The portion of the eighth lens near the optical axis on the exit side is convex, The portion of the eighth lens closest to the optical axis on the side of the object is convex, 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 optical axis thickness of the eighth lens is d15. 0.19≦(R15+R16) / (R15-R16)≦1.15 0.05 ≤ d15 / TTL ≤ 0.16 The above relationship satisfies The microscope objective lens according to feature 1.

14. The portion of the ninth lens near the optical axis on the exit side is concave. The portion of the ninth lens closest to the optical axis on the side of the object is convex, The radius of curvature of the exit side of the ninth lens is R17. The radius of curvature of the object side surface of the ninth lens is R18. The optical axis thickness of the ninth lens is d17. -5.69≦(R17+R18) / (R17-R18)≦-0.82 0.01 ≤ d17 / TTL ≤ 0.04 The above relationship satisfies The microscope objective lens according to feature 1.

15. A composite lens having positive refractive power is formed by bonding the object side of the eighth lens and the output side of the ninth lens together. The combined focal length of the eighth lens and the ninth lens is f8_9. 4.08 ≤ f8_9 / f ≤ 84.27 The above relationship satisfies The microscope objective lens according to feature 1.

16. The portion of the 10th lens near the optical axis on the exit side is convex, The portion of the object side of the tenth lens closest to the optical axis is convex, The radius of curvature of the exit side of the tenth lens is R19. The radius of curvature of the object side surface of the tenth lens is R20. The optical axis thickness of the tenth lens is d19. The focal length of the tenth lens is f10. -1.10≦(R19+R20) / (R19-R20)≦0.31 0.03 ≤ d19 / TTL ≤ 0.11 2.38 ≤ f10 / f ≤ 12.26 The above relationship satisfies The microscope objective lens according to feature 1.

17. The portion of the 11th lens near the optical axis on the exit side is convex, The portion of the 11th lens closest to the optical axis on the side of the object is convex, The radius of curvature of the exit side of the 11th lens is R21. The radius of curvature of the object side surface of the 11th lens is R22. The optical axis thickness of the 11th lens is d21. 0.02≦(R21+R22) / (R21-R22)≦1.02 0.03 ≤ d21 / TTL ≤ 0.13 The above relationship satisfies The microscope objective lens according to feature 1.

18. The portion of the 12th lens near the optical axis on the exit side is concave. The radius of curvature of the exit side of the 12th lens is R23. The radius of curvature of the object side surface of the 12th lens is R24. The optical axis thickness of the 12th lens is d23. -2.18≦(R23+R24) / (R23-R24)≦-0.29 0.01 ≤ d23 / TTL ≤ 0.04 The above relationship satisfies The microscope objective lens according to feature 1.

19. A composite lens having negative refractive power is formed by bonding the object side of the 11th lens and the output side of the 12th lens together. The combined focal length of the 11th lens and the 12th lens is f11_12. -879.88 ≤ f11_12 / f ≤ -5.21 The above relationship satisfies The microscope objective lens according to feature 1.

20. The portion of the 13th lens near the optical axis on the exit side is convex, The radius of curvature of the exit side of the 13th lens is R25. The radius of curvature of the object side surface of the 13th lens is R26. The optical axis thickness of the 13th lens is d25. The focal length of the 13th lens is f13. -3.04≦(R25+R26) / (R25-R26)≦-0.53 0.03 ≤ d25 / TTL ≤ 0.10 1.68 ≤ f13 / f ≤ 7.42 The above relationship satisfies The microscope objective lens according to feature 1.

21. The portion of the 14th lens near the optical axis on the exit side is convex, The portion of the 14th lens closest to the optical axis on the side of the object is convex, The radius of curvature of the exit side of the 14th lens is R27. The radius of curvature of the object side surface of the 14th lens is R28. The optical axis thickness of the 14th lens is d27. -1.06≦(R27+R28) / (R27-R28)≦-0.27 0.04 ≤ d27 / TTL ≤ 0.13 The above relationship satisfies The microscope objective lens according to feature 1.

22. The portion of the 15th lens near the optical axis on the exit side is concave. The portion of the 15th lens closest to the optical axis on the side of the object is concave. The radius of curvature of the exit side of the 15th lens is R29. The radius of curvature of the object side surface of the 15th lens is R30. The optical axis thickness of the 15th lens is d29. -0.05≦(R29+R30) / (R29-R30)≦0.98 0.01 ≤ d29 / TTL ≤ 0.03 The above relationship satisfies The microscope objective lens according to feature 1.

23. The portion of the 16th lens near the optical axis on the exit side is convex, The portion of the 16th lens closest to the optical axis on the side of the object is convex, The radius of curvature of the exit side of the 16th lens is R31. The radius of curvature of the object side surface of the 16th lens is R32. The optical axis thickness of the 16th lens is d31. -1.45≦(R31+R32) / (R31-R32)≦-0.29 0.02 ≤ d31 / TTL ≤ 0.09 The above relationship satisfies The microscope objective lens according to feature 1.

24. The microscope objective lens according to claim 1, characterized in that a composite lens having positive refractive power is formed by bonding the object side of the 14th lens to the output side of the 15th lens, and bonding the object side of the 15th lens to the output side of the 16th lens.

25. The portion of the 17th lens near the optical axis on the exit side is convex, The portion of the 17th lens closest to the optical axis on the side of the object is convex, The radius of curvature of the exit side of the 17th lens is R33. The radius of curvature of the object side surface of the 17th lens is R34. The optical axis thickness of the 17th lens is d33. -1.08≦(R33+R34) / (R33-R34)≦-0.17 0.02 ≤ d33 / TTL ≤ 0.08 The above relationship satisfies The microscope objective lens according to feature 1.

26. The part of the 18th lens near the optical axis on the exit side is concave, The portion of the 18th lens closest to the optical axis on the side of the object is concave. The radius of curvature of the exit side of the 18th lens is R35. The radius of curvature of the object side surface of the 18th lens is R36. The optical axis thickness of the 18th lens is d35. 0.25≦(R35+R36) / (R35-R36)≦0.93 0.01 ≤ d35 / TTL ≤ 0.04 The above relationship satisfies The microscope objective lens according to feature 1.

27. A composite lens having positive refractive power is formed by bonding the object side of the 17th lens and the output side of the 18th lens together. 1.30 ≤ f17_18 / f ≤ 81.29 The above relationship satisfies The microscope objective lens according to feature 1.

Images