Microscope objective

Abstract

Disclosed in the present invention is a microscope objective, having a focal length of f, an optical total length of TTL, and an image height of IH. The combined focal length of first and second lenses is f1_2, the focal lens of a third lens is f3, the combined focal length of fourteenth, fifteenth, and sixteenth lenses is f14_15_16, the combined focal length of seventeenth and eighteenth lenses is f17_18, the on-axis thickness of the seventeenth lens is d33, and the on-axis thickness of the eighteenth lens is d35; and the following relational expressions are satisfied: -3.10≤f1_2 / f3≤-1.80; 3.40≤f14_15_16 / f≤7.00; 4.00≤f17_18 / (d33+d35)≤120.00; and 0.08≤IH*f / TTL≤0.09. The microscope objective of the present invention has a compact lens structure, exhibits excellent optical performance, and satisfies the design requirements of low distortion, 20× magnification, and long working distance.

Description

Microscope objective TECHNICAL FIELD

[0001] The embodiment of the present application relates to the field of optical technology, in particular to a microscope objective suitable for devices such as microscopes. BACKGROUND

[0002] In recent years, the demand for microscope lenses is increasing, and due to the constraints of optical structure, general microscope lenses will have distortion in their microscopic range. On the other hand, since the microscope lens is composed of multiple lenses, its length is inevitably affected, and the long structure of the microscope lens also shortens its working distance, and the magnification is also affected by the working distance, which is not conducive to the use of operators.

[0003] With the development of technology and the increasing of user's diversified needs, scientific research has higher and higher requirements for the observation quality of microscope lenses, and there is an urgent need for microscope lenses with excellent optical characteristics, low distortion, high magnification, and long working distance.

[0004] SUMMARY

[0005] The purpose of the embodiment of the present application is to provide a microscope objective which has a large numerical aperture, a compact lens structure, and good optical performance.

[0006] To solve the above technical problems, the embodiment of the present application provides a microscope objective, which is composed of a first lens, a second lens, a third lens with negative refractive power, a fourth lens, a fifth lens, a sixth lens, a seventh lens with positive refractive power, an eighth lens, a ninth lens, a tenth lens with positive refractive power, an eleventh lens, a twelfth lens, a thirteenth lens with positive refractive power, a fourteenth lens, a fifteenth lens, a sixteenth lens, a seventeenth lens, and an eighteenth lens arranged in order from an exit side to an object side; the focal length of the microscope objective 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 fourteenth lens, the fifteenth lens and the sixteenth lens is f14_15_16, the combined focal length of the seventeenth lens and the eighteenth lens is f17_18, the on-axis thickness of the seventeenth lens is d33, the on-axis thickness of the eighteenth lens is d35, the on-axis distance from the object plane of the microscope objective to the exit surface of the first lens is TTL, the image height of the microscope objective is IH, and the following relationships are satisfied: -3.10≤f1_2 / f3≤-1.80; 3.40≤f14_15_16 / f≤7.00; 4.00≤f17_18 / (d33+d35)≤120.00; 0.08≤IH*f / TTL≤0.09.

[0007] The beneficial effects of the present application are that: through the configuration mode of the lens, the light trend between the lenses can be controlled, the smooth transition of the outgoing light is helpful, the lens structure is compact, the total length of the lens is controlled under the condition of ensuring that the imaging range reaches the expected state, the microscope objective has a large numerical aperture, the light has sufficient convergence ability, and excellent optical performance is ensured, and the design requirements of low distortion, 20 times magnification, and long working distance are met. BRIEF DESCRIPTION OF DRAWINGS

[0008] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced below. For those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0009] Fig. 1 is a structural schematic diagram of a microscope objective of a first embodiment of the present application;

[0010] Fig. 2 is a field curvature and distortion schematic diagram of the camera optical lens shown in Fig. 1;

[0011] Fig. 3 is a magnification chromatic aberration schematic diagram of the camera optical lens shown in Fig. 1;

[0012] Fig. 4 is an axial aberration schematic diagram of the camera optical lens shown in Fig. 1;

[0013] Fig. 5 is a structural schematic diagram of a microscope objective of a second embodiment of the present application;

[0014] Fig. 6 is a field curvature and distortion schematic diagram of the camera optical lens shown in Fig. 5;

[0015] Fig. 7 is a magnification chromatic aberration schematic diagram of the camera optical lens shown in Fig. 5;

[0016] Fig. 8 is an axial aberration schematic diagram of the camera optical lens shown in Fig. 5;

[0017] Fig. 9 is a structural schematic diagram of a microscope objective of a third embodiment of the present application;

[0018] Fig. 10 is a field curvature and distortion schematic diagram of the camera optical lens shown in Fig. 9;

[0019] Fig. 11 is a magnification chromatic aberration schematic diagram of the camera optical lens shown in Fig. 9;

[0020] Fig. 12 is an axial aberration schematic diagram of the camera optical lens shown in Fig. 9;

[0021] Fig. 13 is a structural schematic diagram of a microscope objective of a fourth embodiment of the present application;

[0022] Fig. 14 is a field curvature and distortion schematic diagram of the camera optical lens shown in Fig. 13;

[0023] Fig. 15 is a schematic diagram of the magnification chromatic aberration of the photographing optical lens shown in Fig. 13;

[0024] Fig. 16 is a schematic diagram of the axial aberration of the photographing optical lens shown in Fig. 13. DETAILED DESCRIPTION

[0025] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below with reference to the drawings. However, those skilled in the art can understand that, in the embodiments of the present application, many technical details are presented in order to make the readers better understand the present application. However, the technical solutions claimed by the present application can be implemented even without these technical details and based on various changes and modifications of the following embodiments.

[0026] In the embodiments of the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0027] In addition, in addition to being used to indicate the orientation or positional relationship, the above-mentioned partial terms can also be used to indicate other meanings, for example, the term "upper" can also be used to indicate a certain dependent relationship or connection relationship in some cases. Those skilled in the art can understand the specific meaning of these terms in the present application according to the specific circumstances.

[0028] In addition, the terms "mount", "set", "provided with", "open", "connect", "connected" should be broadly understood. For example, it can be fixedly connected, detachably connected, or integrally constructed; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication between two devices, elements or components. Those skilled in the art can understand the specific meaning of the above-mentioned terms in the present application according to the specific circumstances.

[0029] It has to be understood that any reference to both a first and a second entity e.g. also pertains to the inverse, i.e. a second and a first entity, unless there are specific contrary indications. The terminology used herein is only intended to describe particular embodiments and is in no way intended to limit the scope of the application. It is to be understood that other embodiments can be employed and "includes" should be interpreted as "including but not limited to". As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Expressions such as "at least one of," when preceding the syllables of a list of elements, modify the entire list of elements and do not modify the elements individually. Expressions such as "one or more of," when preceding the syllables of a list of elements, modify the elements individually.

[0030] Referring to FIG. 1, 5, 9, 13, the technical scheme of the present application provides a microscope objective 10, 20, 30, 40, which is sequentially provided with a first lens L1, a second lens L2, a third lens L3 with negative refractive power, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7 with positive refractive power, an eighth lens L8, a ninth lens L9, a tenth lens L10 with positive refractive power, an eleventh lens L11, a twelfth lens L12, a thirteenth lens L13 with positive refractive power, a fourteenth lens L14, a fifteenth lens L15, a sixteenth lens L16, a seventeenth lens L17, and an eighteenth lens L18 from the exit side to the object side.

[0031] The focal length of the microscope objective 10, 20, 30, 40 is f, the combined focal length of the first lens L1 and the second lens L2 is f1_2, the focal length of the third lens L3 is f3, the combined focal length of the fourteenth lens L14, the fifteenth lens L15, and the sixteenth lens L16 is f14_15_16, the combined focal length of the seventeenth lens L17 and the eighteenth lens L18 is f17_18, the on-axis thickness of the seventeenth lens L17 is d33, the on-axis thickness of the eighteenth lens L18 is d35, the on-axis distance from the object plane of the microscope objective 10 to the exit plane of the first lens L1 is TTL, i.e. the total optical length is TTL, the image height of the microscope objective 10 is IH, and the following relationships are satisfied: -3.10≤f1_2 / f3≤-1.80 (1) 3.40≤f14_15_16 / f≤7.00 (2) 4.00≤f17_18 / (d33+d35)≤120.00 (3) 0.08≤IH*f / TTL≤0.09 (4)

[0032] In the conditional expression (1), the ratio of the combined focal length f1_2 of the combined lens composed of the first lens L1 and the second lens L2 to the focal length f3 of the third lens L3 is defined, and within the range defined by the conditional expression (1), the light path between the lenses can be controlled, and the lens structure of the microscope objective 10, 20, 30, 40 is compact.

[0033] In the conditional expression (2), the ratio of the combined focal length f14_15_16 of the lens group at the object side end of the microscope objective 10, 20, 30, 40 composed of the fourteenth lens L14, the fifteenth lens L15 and the sixteenth lens L16 to the focal length f of the microscope objective 10, 20, 30, 40 is defined, and within the range defined by the conditional expression (2), the light rays can have sufficient converging power.

[0034] In the conditional expression (3), the ratio range of the focal length to the thickness of the combined lens composed of the seventeenth lens L17 and the eighteenth lens L18 is defined, and within the range defined by the conditional expression (3), the combined lens can have sufficient refractive power while maintaining a reasonable thickness.

[0035] In the conditional expression (4), the ratio range of the product of the image height IH and the focal length f of the microscope objective 10, 20, 30, 40 to the total optical length TTL is defined, and within the range, the total length of the microscope objective 10, 20, 30, 40 can be controlled when the imaging range reaches the desired state.

[0036] In the present scheme, by the above arrangement, the light path between the lenses can be controlled, the transition of the outgoing light is smooth, the lens structure is compact, the total length of the lens can be controlled when the imaging range reaches the desired state, the microscope objective has a large numerical aperture, the light rays have sufficient converging power, and the microscope objective has excellent optical performance, meeting the design requirements of low distortion, 20 times magnification, and long working distance.

[0037] It should be noted that the units of the focal length, the thickness, the image height and the total optical length are millimeters.

[0038] For example, the radius of curvature of the exit side surface of the tenth lens is R19, the radius of curvature of the object side surface of the tenth lens is R20, and the following relationship is satisfied: -1.60≤R19 / R20≤-2.50 (5)

[0039] In the conditional expression (5), the shape of the tenth lens L10 is defined, which helps to smooth the transition of the outgoing light and improve the imaging quality.

[0040] For example, the on-axis distance from the object plane of the objective lens to the object side surface of the eighteenth lens is WD, i.e., the working distance is WD, the numerical aperture of the objective lens is NA, and the following relationship is satisfied: WD*NA≥1.10 (6)

[0041] The conditional expression (6) defines the range of the product of the working distance WD and the numerical aperture NA of the objective lens 10, 20, 30, 40, by limiting the upper limit, the working distance WD of the objective lens 10, 20, 30, 40 can be prevented from being too long relative to the numerical aperture NA, so as to achieve satisfactory aberration performance and higher resolution. In addition, by limiting the lower limit of the above product, the working distance WD can be prevented from being too short, and the user does not have to pay too much attention to prevent the objective lens from colliding with the observed object, thereby improving the work efficiency when measuring. In particular, when observing with an objective lens, it is often the case that an objective lens with a low numerical aperture is used to observe an object with a very uneven surface. By limiting the lower limit of WD*NA, the present scheme can ensure that the low numerical aperture objective lens has a long enough working distance. Thus, even the observed object with a large uneven surface can be measured, so as to achieve high versatility of the objective lens. In other words, within the range defined by the conditional expression (6), the objective lens can have sufficient resolution and high work efficiency and high versatility.

[0042] In one scheme, the exit side surface of the first lens L1 is convex at the paraxial region, and the object side surface thereof is convex at the paraxial region. In other alternative schemes, the object side surface and the exit side surface of the first lens L1 can also be provided with other concave and convex distributions.

[0043] For example, the radius of curvature of the exit side surface of the first lens is R1, the radius of curvature of the object side surface of the first lens is R2, the on-axis thickness of the first lens is d1, and the following relationship is satisfied: -1.39≤(R1+R2) / (R1-R2)≤-0.24 (7) 0.03≤d1 / TTL≤0.10 (8)

[0044] The conditional expression (7) defines the shape of the first lens Ll, and reasonable control of the shape of the first lens Ll can moderate the degree of deflection of light rays after passing through the first lens Ll, effectively reduce aberration, and also satisfy the relationship -0.87≤(Rl+R2) / (Rl-R2)≤-0.30. The conditional expression (8) defines the ratio range of the on-axis thickness dl of the first lens Ll to the total optical length TTL of the microscope objective 10, 20, 30, 40, and within the range, the thickness of the first lens Ll is controlled, the total optical length TTL of the microscope objective 10, 20, 30, 40 is further controlled, and also the relationship 0.05≤dl / TTL≤0.08 is satisfied.

[0045] In one aspect, the exit side of the second lens L2 is concave at the paraxial region, and the object side of the second lens L2 is concave at the paraxial region. In other alternative aspects, the object side and the exit side of the second lens L2 can also be provided with other concave or convex distributions.

[0046] For example, the exit side of the second lens has a radius of curvature R3, the object side of the second lens has a radius of curvature R4, the on-axis thickness of the second lens is d3, and the following relationships are satisfied: 0.15≤(R3+R4) / (R3-R4)≤1.13 (9) 0.01≤d3 / TTL≤0.06 (10)

[0047] The conditional expression (9) defines the shape of the second lens, and within the range defined by the conditional expression (9), the second lens L2 can effectively correct the system spherical aberration, and also satisfy the relationship 0.23≤(R3+R4) / (R3-R4)≤0.90. The conditional expression (10) defines the ratio range of the on-axis thickness d3 of the second lens L2 to the total optical length TTL of the microscope objective 10, 20, 30, 40, and within the range, the total optical length TTL of the microscope objective 10, 20, 30, 40 is reasonably controlled, and also satisfy the relationship 0.01≤d3 / TTL≤0.05.

[0048] For example, the object side of the first lens Ll and the exit side of the second lens L2 are cemented to form a combined lens with positive refractive power, and the following relationship is satisfied: 1.93≤f1_2 / f≤8.42 (11)

[0049] In one aspect, the exit side of the third lens L3 is concave or convex at the paraxial region, and the object side of the third lens L3 is concave at the paraxial region. In other alternative aspects, the object side of the third lens L3 can also be provided with a convex distribution.

[0050] For example, the fourth lens L4 has an exit side surface with a radius of curvature R7, an object side surface with a radius of curvature R8, and an on-axis thickness d7, and satisfies the following relationships: -2.94 ≤ (R7+R8) / (R7-R8) ≤ -0.12 (15) 0.01 ≤ d7 / TTL ≤ 0.06 (16)

[0051] Condition (12) defines the shape of the third lens L3, which helps to reduce the aberration of the microscope objective 10, 20, 30, 40, and also satisfies the relationship 0.24 ≤ (R5+R6) / (R5-R6) ≤ 1.25. Condition (13) defines the ratio of the on-axis thickness d15 of the third lens L3 to the total optical length TTL of the microscope objective 10, 20, 30, 40, which helps to control the total optical length TTL of the microscope objective 10, 20, 30, 40, and also satisfies the relationship 0.01 ≤ d5 / TTL ≤ 0.02. Condition (14) defines the ratio of the focal length f3 of the third lens L3 to the focal length f of the microscope objective 10, 20, 30, 40, which helps to reduce the aberration and improve the imaging quality, and also satisfies the relationship -2.62 ≤ f3 / f ≤ -1.55.

[0052] In one aspect, the exit side surface of the fourth lens L4 is concave at the paraxial region, and the object side surface of the fourth lens L4 is concave or convex at the paraxial region. In other alternative aspects, the exit side surface of the fourth lens L4 can also be convex.

[0053] For example, the fourth lens L4 has an exit side surface with a radius of curvature R7, an object side surface with a radius of curvature R8, and an on-axis thickness d7, and satisfies the following relationships: -2.94 ≤ (R7+R8) / (R7-R8) ≤ -0.12 (15) 0.01 ≤ d7 / TTL ≤ 0.06 (16)

[0054] Condition (15) defines the shape of the fourth lens L4, which enables the fourth lens L4 to effectively correct the system spherical aberration, and also satisfies the relationship -1.84 ≤ (R7+R8) / (R7-R8) ≤ -0.15. Condition (16) defines the ratio of the on-axis thickness d7 of the fourth lens L4 to the total optical length TTL of the microscope objective 10, 20, 30, 40, which helps to control the total optical length TTL of the microscope objective 10, 20, 30, 40, and also satisfies the relationship 0.01 ≤ d7 / TTL ≤ 0.05.

[0055] In one embodiment, the exit side surface of the fifth lens L5 is convex or concave at the paraxial region, and the object side surface of the fifth lens L5 is convex at the paraxial region. In other alternative embodiments, the object side surface of the fifth lens L5 can also be concave.

[0056] For example, 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 on-axis thickness of the fifth lens is d9, and the following relationships are satisfied: 0.11≤(R9+R10) / (R9-R10)≤2.20 (17) 0.04≤d9 / TTL≤0.15 (18)

[0057] Condition (17) defines the shape of the fifth lens L5. Within this range, it is helpful to reduce the spherical aberration of the microscope objective 10, 20, 30, 40, to improve the imaging quality, and in addition, the relationship 0.18≤(R9+R10) / (R9-R10)≤1.76 can also be satisfied. Condition (18) defines the range of the ratio of the on-axis thickness d9 of the fifth lens L5 to the total optical length TTL of the microscope objective 10, 20, 30, 40. Within the range defined by condition (18), it is advantageous to reasonably control the total optical length TTL of the microscope objective 10, 20, 30, 40, and in addition, the relationship 0.06≤d9 / TTL≤0.12 can also be satisfied.

[0058] In one embodiment, the exit side surface of the sixth lens L6 is concave at the paraxial region, and the object side surface of the sixth lens L6 is convex at the paraxial region. In other alternative embodiments, the object side surface and the exit side surface of the sixth lens L6 can also be provided with other concave-convex distributions.

[0059] For example, 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 on-axis thickness of the sixth lens L6 is d11, and the following relationships are satisfied: -10.75≤(R11+R12) / (R11-R12)≤-2.17 (19) 0.01≤d11 / TTL≤0.03 (20)

[0060] The conditional expression (19) defines the shape of the sixth lens L6, and reasonable control of the shape of the sixth lens L6 is conducive to correcting the aberration of the off-axis angle and other problems, and in addition, the relationship -6.72≤(R11+R12) / (R11-R12)≤-2.71 can also be met. The conditional expression (20) defines the on-axis thickness d11 of the sixth lens L6, and within the range defined by the conditional expression (20), the optical total length TTL of the microscope objective 10, 20, 30, 40 can be effectively controlled, and in addition, the relationship 0.02≤d11 / TTL≤0.03 can also be met.

[0061] For example, the object side surface of the fourth lens L4 is cemented with the exit side surface of the fifth lens L5, and the object side surface of the fifth lens L5 is cemented with the exit side surface of the sixth lens L6 to form a combined lens with negative refractive power, the combined focal length of the fourth lens L4, the fifth lens L5 and the sixth lens L6 is f4_5_6, and the following relationship is met: -7.70≤f4_5_6 / f≤-1.41 (21)

[0062] The conditional expression (21) defines the range of the ratio of the combined focal length of the combined lens composed of the fourth lens L4, the fifth lens L5 and the sixth lens L6 to the focal length f of the microscope objective 10, 20, 30, 40, and within the above range, the optical performance of the microscope objective 10, 20, 30, 40 can be improved, and in addition, the relationship -4.81≤f4_5_6 / f≤-1.77 can also be met.

[0063] In one scheme, the exit side surface of the seventh lens L7 is concave or convex at the near axis, and the object side surface thereof is convex at the near axis. In other alternative schemes, the object side surface of the seventh lens L7 can also be provided as concave.

[0064] For example, the radius of curvature of the exit side surface of the seventh lens L7 is R13, the radius of curvature of the object side surface of the seventh lens L7 is R14, the on-axis thickness of the seventh lens L7 is d13, the focal length of the seventh lens L7 is f7, and the following relationship is met: 0.41≤(R13+R14) / (R13-R14)≤2.60 (22) 0.02≤d13 / TTL≤0.09 (23) 2.16≤f7 / f≤7.34 (24)

[0065] The conditional expression (22) defines the shape of the seventh lens L7. Within the range of the conditional expression, the seventh lens L7 can effectively correct the system spherical aberration, which helps to improve the imaging quality, and in addition, the relationship 0.66≤(R13+R14) / (R13-R14)≤2.08 can be met. The conditional expression (23) defines the on-axis thickness d13 of the seventh lens L7. Within the range, it helps to compress the total optical length TTL of the microscope objective 10, 20, 30, 40, and in addition, the relationship 0.04≤d13 / TTL≤0.07 can be met. The conditional expression (24) defines the ratio of the focal length f7 of the seventh lens L7 to the focal length f of the microscope objective 10, 20, 30, 40. Within the range of the conditional expression, it helps to reduce aberration and improve imaging quality, and in addition, the relationship 3.46≤f7 / f≤5.87 can be met.

[0066] In one scheme, the exit side of the eighth lens L8 is convex at the paraxial region, and the object side of the eighth lens L8 is convex at the paraxial region. In other alternative schemes, the object side and the exit side of the eighth lens L8 can also be provided with other concave and convex distribution conditions.

[0067] For example, 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 on-axis thickness of the eighth lens L8 is d15, and the following relationships are met: 0.19≤(R15+R16) / (R15-R16)≤1.15 (25) 0.05≤d15 / TTL≤0.16 (26)

[0068] The conditional expression (25) defines the shape of the eighth lens L8. Within the range defined by the conditional expression, the degree of deflection of light passing through the eighth lens L8 can be moderated, and aberration can be effectively reduced, and in addition, the relationship 0.30≤(R15+R16) / (R15-R16)≤0.92 can be met. The conditional expression (26) defines the on-axis thickness d15 of the eighth lens L8. Within the range, it helps to compress the total optical length TTL of the microscope objective 10, 20, 30, 40, and in addition, the relationship 0.08≤d15 / TTL≤0.13 can be met.

[0069] In one scheme, the exit side of the ninth lens L9 is concave at the paraxial region, and the object side of the ninth lens L9 is convex at the paraxial region. In other alternative schemes, the object side and the exit side of the ninth lens L9 can also be provided with other concave and convex distribution conditions.

[0070] For example, the radius of curvature of the exit side surface of the ninth lens L9 is R17, the radius of curvature of the object side surface of the ninth lens L9 is R18, the thickness of the ninth lens L9 on the optical axis is d17, and the following relationships are satisfied: -5.69 ≤ (R17+R18) / (R17-R18) ≤ -0.82 (27) 0.01 ≤ d17 / TTL ≤ 0.04 (28)

[0071] The conditional expression (27) defines the shape of the ninth lens L9, and within the range defined by the conditional expression, the optical performance of the microscope objective 10, 20, 30, 40 is improved, and the relationship -3.56 ≤ (R17+R18) / (R17-R18) ≤ -1.02 is also satisfied. The conditional expression (28) defines the ratio of the thickness d17 of the ninth lens L9 to the total optical length TTL of the microscope objective 10, 20, 30, 40, and within the range defined by the conditional expression, the total optical length TTL of the microscope objective 10, 20, 30, 40 is reasonably controlled, and the relationship 0.02 ≤ d17 / TTL ≤ 0.03 is also satisfied.

[0072] For example, the object side surface of the eighth lens L8 and the exit side surface of the ninth lens L9 are cemented to form a combined lens having positive refractive power, the combined focal length of the eighth lens L8 and the ninth lens L9 is f8_9, and the following relationship is satisfied: 4.08 ≤ f8_9 / f ≤ 84.27 (29)

[0073] The conditional expression (29) defines the ratio of the focal length f8_9 of the combined lens formed by the eighth lens L8 and the ninth lens L9 to the focal length f of the microscope objective 10, 20, 30, 40, and in this way, the optical performance of the microscope objective 10, 20, 30, 40 can be improved, and the relationship 6.53 ≤ f8_9 / f ≤ 67.42 is also satisfied.

[0074] In the present scheme, the exit side surface of the tenth lens L10 is convex at the paraxial region, and the object side surface of the tenth lens L10 is convex at the paraxial region. In other alternative schemes, the object side surface and the exit side surface of the tenth lens L10 can also be provided with other concave and convex distributions.

[0075] For example, the eleventh lens L11 has a radius of curvature R21 of the exit side surface, a radius of curvature R22 of the object side surface, an on-axis thickness d21, and satisfies the following relationships: 0.02≤(R21+R22) / (R21-R22)≤1.02 (33) 0.03≤d21 / TTL≤0.13 (34)

[0076] Condition (30) defines the shape of the tenth lens L10. In this range, the degree of light refraction after the first lens L1 can be moderated, aberration can be effectively reduced, and the relationship -0.69≤(R19+R20) / (R19-R20)≤0.25 can also be satisfied. Condition (31) defines the on-axis thickness d19 of the tenth lens L10, which helps to compress the total optical length TTL of the microscope 10, 20, 30, 40, and the relationship 0.06≤d19 / TTL≤0.12 can also be satisfied. Condition (32) defines the range of the ratio of the focal length of the tenth lens L10 to the focal length f of the microscope 10, 20, 30, 40, which helps to reduce aberration, improve imaging quality, and the relationship 3.81≤f10 / f≤9.81 can also be satisfied.

[0077] In this embodiment, the exit side surface of the eleventh lens L11 is convex near the axis, and the object side surface of the eleventh lens L11 is convex near the axis. In other alternative embodiments, the object side surface and the exit side surface of the tenth lens L10 can also be provided with other concave or convex distributions.

[0078] For example, the eleventh lens L11 has a radius of curvature R21 of the exit side surface, a radius of curvature R22 of the object side surface, an on-axis thickness d21, and satisfies the following relationships: 0.02≤(R21+R22) / (R21-R22)≤1.02 (33) 0.03≤d21 / TTL≤0.13 (34)

[0079] The conditional expression (33) defines the shape of the eleventh lens L11, and within the range defined by the conditional expression, the degree of deflection of light passing through the eleventh lens L11 can be mitigated, aberrations can be effectively reduced, and in addition, the relationship 0.04 ≤ (R21+R22) / (R21-R22) ≤ 0.81 can be satisfied. The conditional expression (34) defines the on-axis thickness d21 of the eleventh lens L11, and the optical total length TTL of the microscope objective 10, 20, 30, 40 can be effectively compressed, the structure of the microscope objective 10, 20, 30, 40 can be made compact, and in addition, the relationship 0.04 ≤ d21 / TTL ≤ 0.11 can be satisfied.

[0080] In one aspect, the exit side surface of the twelfth lens L12 is concave at the paraxial region, and the object side surface of the twelfth lens L12 is concave or convex at the paraxial region. In other possible aspects, the exit side surface of the twelfth lens L12 can also be provided as convex.

[0081] For example, the exit side surface of the twelfth lens L12 has a curvature radius R23, the object side surface of the twelfth lens L12 has a curvature radius R24, and the on-axis thickness of the twelfth lens L12 is d23, and the following relationships are satisfied: -2.18 ≤ (R23+R24) / (R23-R24) ≤ -0.29 (35) 0.01 ≤ d23 / TTL ≤ 0.04 (36)

[0082] The conditional expression (35) defines the shape of the twelfth lens L12, so that the twelfth lens L12 can effectively correct the system spherical aberration, and in addition, the relationship -1.37 ≤ (R23+R24) / (R23-R24) ≤ -0.36 can be satisfied. The conditional expression (36) defines the on-axis thickness d23 of the twelfth lens L12, and within this range, the optical total length TTL of the microscope objective 10 can be controlled, and in addition, the relationship 0.02 ≤ d23 / TTL ≤ 0.03 can be satisfied.

[0083] For example, the object side surface of the eleventh lens L11 and the exit side surface of the twelfth lens L12 are cemented to form a combined lens having negative refractive power, the combined focal length of the eleventh lens L11 and the twelfth lens L12 is f11_12, and the following relationship is satisfied: -879.88 ≤ f11_12 / f ≤ -5.21 (37)

[0084] The conditional expression (37) defines a range of the ratio of the combined focal length f11_12 of the combined lens composed of the eleventh lens L11 and the twelfth lens L12 to the focal length f of the microscope objective 10, 20, 30, 40, which helps to improve the optical performance of the microscope objective 10, 20, 30, 40, and in addition, the relationship -549.93≤f11_12 / f≤-6.51 can also be satisfied.

[0085] In one scheme, the exit side surface of the thirteenth lens L13 is convex at the paraxial region, and the object side surface of the thirteenth lens L13 is concave or convex at the paraxial region. In other alternative schemes, the exit side surface of the thirteenth lens L13 can also be provided as concave.

[0086] For example, the radius of curvature of the exit side surface of the thirteenth lens L13 is R25, the radius of curvature of the object side surface of the thirteenth lens L13 is R26, the on-axis thickness of the thirteenth lens L13 is d25, the focal length of the thirteenth lens L13 is f13, and the following relationships are satisfied: -3.04≤(R25+R26) / (R25-R26)≤-0.53 (38) 0.03≤d25 / TTL≤0.10 (39) 1.68≤f13 / f≤7.42 (40)

[0087] The conditional expression (38) defines the shape of the thirteenth lens L13, and in this range, the spherical aberration of the microscope objective 10, 20, 30, 40 can be reduced, and in addition, the relationship -1.90≤(R25+R26) / (R25-R26)≤-0.66 can also be satisfied. The conditional expression (39) defines the on-axis thickness d25 of the thirteenth lens L13, and in this range, it is beneficial to effectively compress the total optical length TTL of the microscope objective 10, 20, 30, 40, and in addition, the relationship 0.05≤d25 / TTL≤0.08 can also be satisfied. The conditional expression (40) defines a range of the ratio of the focal length f13 of the thirteenth lens L13 to the focal length f of the microscope objective 10, 20, 30, 40, which helps to reduce aberration and improve imaging quality, and in addition, the relationship 2.69≤f13 / f≤5.93 can also be satisfied.

[0088] In one scheme, the exit side surface of the fourteenth lens L14 is convex at the paraxial region, and the object side surface of the fourteenth lens L14 is convex at the paraxial region. In other alternative schemes, the exit side surface and the object side surface of the fourteenth lens L14 can also be provided in other concave and convex distribution cases.

[0089] For example, the radius of curvature of the exit side surface of the fourteenth lens L14 is R27, the radius of curvature of the object side surface of the fourteenth lens L14 is R28, the on-axis thickness of the fourteenth lens L14 is d27, and the following relational expression is satisfied: -1.06 ≤ (R27+R28) / (R27-R28) ≤ -0.27 (41) 0.04 ≤ d27 / TTL ≤ 0.13 (42)

[0090] The conditional expression (41) specifies the shape of the fourteenth lens L14, and within the above range, the fourteenth lens L14 can effectively correct the system spherical aberration, and in addition, the relational expression -0.66 ≤ (R27+R28) / (R27-R28) ≤ -0.34 can be satisfied. The conditional expression (42) specifies the on-axis thickness d27 of the fourteenth lens L14, and helps to compress the optical total length TTL of the microscope objective 10, 20, 30, 40, and in addition, the relational expression 0.07 ≤ d27 / TTL ≤ 0.10 can be satisfied.

[0091] In one aspect, the exit side surface of the fifteenth lens L15 is concave at the paraxial region, and the object side surface of the fifteenth lens L15 is concave at the paraxial region. In other alternative aspects, the exit side surface and the object side surface of the fifteenth lens L15 can also be provided with other concave or convex distributions.

[0092] For example, the radius of curvature of the exit side surface of the fifteenth lens L15 is R29, the radius of curvature of the object side surface of the fifteenth lens L15 is R30, the on-axis thickness of the fifteenth lens L15 is d29, and the following relational expression is satisfied: -0.05 ≤ (R29+R30) / (R29-R30) ≤ 0.98 (43) 0.01 ≤ d29 / TTL ≤ 0.03 (44)

[0093] The conditional expression (43) specifies the shape of the fifteenth lens L15, and within the range, the degree of deflection of light passing through the fifteenth lens L15 can be moderated, and aberrations can be effectively reduced, and in addition, the relational expression -0.03 ≤ (R29+R30) / (R29-R30) ≤ 0.79 can be satisfied. The conditional expression (44) specifies the on-axis thickness d29 of the fifteenth lens L15, and helps to compress the optical total length TTL of the microscope objective 10, 20, 30, 40, and in addition, the relational expression 0.01 ≤ d29 / TTL ≤ 0.02 can be satisfied.

[0094] In one embodiment, the exit side surface of the sixteenth lens L16 is convex at the paraxial region, and the object side surface of the sixteenth lens L16 is convex at the paraxial region. In other alternative embodiments, the exit side surface and the object side surface of the sixteenth lens L16 can also be configured in other concave-convex distribution.

[0095] For example, the radius of curvature of the exit side surface of the sixteenth lens L16 is R31, the radius of curvature of the object side surface of the sixteenth lens L16 is R32, the on-axis thickness of the sixteenth lens L16 is d31, and the following relationships are satisfied: -1.45≤(R31+R32) / (R31-R32)≤-0.29 (45) 0.02≤d31 / TTL≤0.09 (46)

[0096] Condition (45) defines the shape of the sixteenth lens L16. Within the range, the degree of deflection of light passing through the sixteenth lens L16 can be moderated, aberrations can be effectively reduced, and the relationship -0.91≤(R31+R32) / (R31-R32)≤-0.36 can also be satisfied. Condition (46) defines the on-axis thickness d31 of the sixteenth lens L16. Within the range, the optical performance of the first microscope objective 10, 20, 30, 40 can be improved, and the relationship 0.03≤d31 / TTL≤0.07 can also be satisfied.

[0097] In one embodiment, the object side surface of the fourteenth lens L14 is cemented to the exit side surface of the fifteenth lens L15, and the object side surface of the fifteenth lens L15 is cemented to the exit side surface of the sixteenth lens L16 to form a combined lens having positive refractive power.

[0098] In one embodiment, the exit side surface of the seventeenth lens L17 is convex at the paraxial region, and the object side surface of the seventeenth lens L17 is convex at the paraxial region. In other alternative embodiments, the exit side surface and the object side surface of the seventeenth lens L17 can also be configured in other concave-convex distribution.

[0099] For example, the radius of curvature of the exit side surface of the seventeenth lens L17 is R33, the radius of curvature of the object side surface of the seventeenth lens L17 is R34, the on-axis thickness of the seventeenth lens L17 is d33, and the following relationships are satisfied: -1.08≤(R33+R34) / (R33-R34)≤-0.17 (47) 0.02≤d33 / TTL≤0.08 (48)

[0100] The conditional expression (47) defines the shape of the seventeenth lens L17, within the range, the optical performance and imaging quality of the microscope objective 10 can be improved, and in addition, the relationship -0.67≤(R33+R34) / (R33-R34)≤-0.22 can also be met. The conditional expression (48) defines the ratio range of the on-axis thickness d33 of the seventeenth lens L17 and the total optical length TTL of the microscope objective 10, 20, 30, 40, which is conducive to controlling the total optical length TTL of the microscope objective 10, 20, 30, 40, and in addition, the relationship 0.04≤d33 / TTL≤0.06 can also be met.

[0101] In one scheme, the exit side of the eighteenth lens L18 is concave at the near axis, and the object side of the eighteenth lens L18 is concave at the near axis. In other alternative schemes, the exit side and the object side of the eighteenth lens L18 can also be provided with other concave and convex distribution conditions.

[0102] For example, the radius of curvature of the exit side of the eighteenth lens L18 is R35, the radius of curvature of the object side of the eighteenth lens L18 is R36, the on-axis thickness of the eighteenth lens L18 is d35, and the following relationship is met: 0.25≤(R35+R36) / (R35-R36)≤0.93 (49) 0.01≤d35 / TTL≤0.04 (50)

[0103] The conditional expression (49) defines the shape of the eighteenth lens L18, within the range, the degree of deflection of light rays passing through the eighteenth lens L18 can be eased, and the aberration can be effectively reduced, and in addition, the relationship 0.40≤(R35+R36) / (R35-R36)≤0.74 can also be met. The conditional expression (50) defines the on-axis thickness d35 of the eighteenth lens L18, within the above range, which is conducive to compressing the total optical length TTL of the microscope objective 10, 20, 30, 40, and in addition, the relationship 0.01≤d35 / TTL≤0.03 can also be met.

[0104] In the present scheme, the exit side of the seventeenth lens L17 and the object side of the eighteenth lens L18 are cemented to form a combined lens with positive refractive power, and the combined focal length f17_18 of the combined lens also meets the following relationship: 1.30≤f17_18 / f≤81.29 (51)

[0105] Within the conditional range defined by the conditional expression (51), the optical performance of the microscope objective 10, 20, 30, 40 can be improved. In addition, the relationship 2.08≤f17_18 / f≤65.03 can also be met.

[0106] In the present scheme, an optical element such as an optical filter GF is arranged on the object side of the eighteenth lens L18, wherein the optical filter GF can be a glass cover plate or an optical filter (filter). As shown in FIG. 1. In other schemes, the optical filter GF can also be arranged at other positions.

[0107] The microscope objective 10, 20, 30, 40 of the present application can control the light path between lenses, make the lens structure compact, control the total length of the lens under the condition of ensuring the imaging range to reach the expected state, make the microscope objective have a large numerical aperture, ensure that the light has sufficient convergence ability, and has excellent optical performance, meets the design requirements of low distortion, 20 times magnification, long working distance.

[0108] The microscope objective 10 of the present application will be described below by examples. The symbols recorded in each example are shown in Table 【1】, and the units of focal length, on-axis distance, radius of curvature, on-axis thickness, inflection point position, and stationary point position are millimeters.

[0109] TTL: total optical length (on-axis distance from the object side of the first lens L1 to the imaging surface), unit: millimeter.

[0110] First embodiment:

[0111] The exit side of the first lens L1 is convex at the paraxial region, and the object side is convex at the paraxial region;

[0112] The exit side of the second lens L2 is concave at the paraxial region, and the object side is concave at the paraxial region;

[0113] The third lens L3 has a negative refractive power, the exit side is concave at the paraxial region, and the object side is concave at the paraxial region;

[0114] The exit side of the fourth lens L4 is concave at the paraxial region, and the object side is concave at the paraxial region;

[0115] The exit side of the fifth lens L5 is convex at the paraxial region, and the object side is convex at the paraxial region;

[0116] The exit side of the sixth lens L6 is concave at the paraxial region, and the object side is convex at the paraxial region;

[0117] The seventh lens L7 has a positive refractive power, the exit side is convex at the paraxial region, and the object side is convex at the paraxial region;

[0118] The exit side of the eighth lens L8 is convex at the paraxial region, and the object side is convex at the paraxial region;

[0119] The exit side of the ninth lens L9 is concave at the paraxial region, and the object side is convex at the paraxial region;

[0120] The tenth lens L10 has positive refractive power, and its exit side surface is convex at the vicinity of the optical axis, and its object side surface is convex at the vicinity of the optical axis;

[0121] The eleventh lens L11 has positive refractive power, and its exit side surface is convex at the vicinity of the optical axis, and its object side surface is convex at the vicinity of the optical axis;

[0122] The twelfth lens L12 has negative refractive power, and its exit side surface is concave at the vicinity of the optical axis, and its object side surface is concave at the vicinity of the optical axis;

[0123] The thirteenth lens L13 has positive refractive power, and its exit side surface is convex at the vicinity of the optical axis, and its object side surface is concave at the vicinity of the optical axis;

[0124] The fourteenth lens L14 has positive refractive power, and its exit side surface is convex at the vicinity of the optical axis, and its object side surface is convex at the vicinity of the optical axis;

[0125] The fifteenth lens L15 has negative refractive power, and its exit side surface is concave at the vicinity of the optical axis, and its object side surface is concave at the vicinity of the optical axis;

[0126] The sixteenth lens L16 has positive refractive power, and its exit side surface is convex at the vicinity of the optical axis, and its object side surface is convex at the vicinity of the optical axis;

[0127] The seventeenth lens L17 has positive refractive power, and its exit side surface is convex at the vicinity of the optical axis, and its object side surface is convex at the vicinity of the optical axis;

[0128] The eighteenth lens L18 has negative refractive power, and its exit side surface is concave at the vicinity of the optical axis, and its object side surface is concave at the vicinity of the optical axis.

[0129] Fig. 1 is a structural schematic view of a microscope objective 10 in a first embodiment. The design data of the microscope objective 10 in the first embodiment of the present application is shown below.

[0130] Table 1 lists the radius of curvature R of the exit side surface and the object side surface, the thickness of the lens on the optical axis, the distance d on the optical axis between the lenses, the refractive index nd, and the Abbe number vd of the first lens L1 to the eighteenth lens L18 constituting the microscope objective 10 in the first embodiment of the present application. Note that in the present embodiment, the units of distance, radius, and thickness are millimeters (mm).

[0131]

Table 1

[0132] The meanings of the symbols in the above table are as follows.

[0133] R: radius of curvature of an optical surface, central radius of curvature in the case of a lens;

[0134] ST: stop;

[0135] R1: radius of curvature of the exit side surface of the first lens L1;

[0136] R2: radius of curvature of the object side surface of the first lens L1;

[0137] R3: radius of curvature of the exit side surface of the second lens L2;

[0138] R4: radius of curvature of the object side surface of the second lens L2;

[0139] R5: radius of curvature of the exit side surface of the third lens L3;

[0140] R6: radius of curvature of the object side surface of the third lens L3;

[0141] R7: radius of curvature of the exit side surface of the fourth lens L4;

[0142] R8: radius of curvature of the object side surface of the fourth lens L4;

[0143] R9: radius of curvature of the exit side surface of the fifth lens L5;

[0144] R10: radius of curvature of the object side surface of the fifth lens L5;

[0145] R11: radius of curvature of the exit side surface of the sixth lens L6;

[0146] R12: radius of curvature of the object side surface of the sixth lens L6;

[0147] R13: radius of curvature of the exit side surface of the seventh lens L7;

[0148] R14: radius of curvature of the object side surface of the seventh lens L7;

[0149] R15: radius of curvature of the exit side surface of the eighth lens L8;

[0150] R16: radius of curvature of the object side surface of the eighth lens L8;

[0151] R17: radius of curvature of the exit side surface of the ninth lens L9;

[0152] R18: radius of curvature of the object side surface of the ninth lens L9;

[0153] R19: radius of curvature of the exit side surface of the tenth lens L10;

[0154] R20: radius of curvature of the object side surface of the tenth lens L10;

[0155] R21: radius of curvature of the exit side surface of the eleventh lens L11;

[0156] R22: radius of curvature of the object side surface of the eleventh lens L11;

[0157] R23: radius of curvature of the exit side surface of the twelfth lens L12;

[0158] R24: radius of curvature of the object side surface of the twelfth lens L12;

[0159] R25: radius of curvature of the exit side surface of the thirteenth lens L13;

[0160] R26: radius of curvature of the object side surface of the thirteenth lens L13;

[0161] R27: radius of curvature of the exit side surface of the fourteenth lens L14;

[0162] R28: radius of curvature of the object side surface of the fourteenth lens L14;

[0163] R29: radius of curvature of the exit side surface of the fifteenth lens L15;

[0164] R30: radius of curvature of the object side surface of the fifteenth lens L15;

[0165] R31: radius of curvature of the exit side surface of the sixteenth lens L16;

[0166] R32: radius of curvature of the object side surface of the sixteenth lens L16;

[0167] R33: radius of curvature of the exit side surface of the seventeenth lens L17;

[0168] R34: radius of curvature of the object side surface of the seventeenth lens L17;

[0169] R35: radius of curvature of the exit side surface of the eighteenth lens L18;

[0170] R36: radius of curvature of the object side surface of the eighteenth lens L18;

[0171] d: on-axis thickness of a lens, on-axis distance between lenses;

[0172] d1: on-axis thickness of the first lens L1;

[0173] d2: on-axis distance from the exit side surface of the first lens L1 to the object side surface of the second lens L2;

[0174] d3: on-axis thickness of the second lens L2;

[0175] d4: on-axis distance from the exit side surface of the second lens L2 to the object side surface of the third lens L3;

[0176] d5: on-axis thickness of the third lens L3;

[0177] d6: on-axis distance from the exit side surface of the third lens L3 to the object side surface of the fourth lens L4;

[0178] d7: on-axis thickness of the fourth lens L4;

[0179] d8: on-axis distance from the exit side of the fourth lens L4 to the object side of the fifth lens L5;

[0180] d9: on-axis thickness of the fifth lens L5;

[0181] d10: on-axis distance from the exit side of the fifth lens L5 to the object side of the sixth lens L6;

[0182] d11: on-axis thickness of the sixth lens L6;

[0183] d12: on-axis distance from the exit side of the sixth lens L6 to the object side of the seventh lens L7;

[0184] d13: on-axis thickness of the seventh lens L7;

[0185] d141: on-axis distance from the exit side of the seventh lens L7 to the stop ST;

[0186] d142: on-axis distance from the stop ST to the object side of the eighth lens L8;

[0187] d15: on-axis thickness of the eighth lens L8;

[0188] d16: on-axis distance from the exit side of the eighth lens L8 to the object side of the ninth lens L9;

[0189] d17: on-axis thickness of the ninth lens L9;

[0190] d18: on-axis distance from the exit side of the ninth lens L9 to the object side of the tenth lens L10;

[0191] d19: on-axis thickness of the tenth lens L10;

[0192] d20: on-axis distance from the exit side of the tenth lens L10 to the object side of the eleventh lens L11;

[0193] d21: on-axis thickness of the eleventh lens L11;

[0194] d22: on-axis distance from the exit side of the eleventh lens L11 to the object side of the twelfth lens L12;

[0195] d23: on-axis thickness of the twelfth lens L12;

[0196] d24: on-axis distance from the exit side of the twelfth lens L12 to the object side of the thirteenth lens L13;

[0197] d25: on-axis thickness of the thirteenth lens L13;

[0198] d26: an on-axis distance from the exit side surface of the thirteenth lens L13 to the object side surface of the fourteenth lens L14;

[0199] d27: an on-axis thickness of the fourteenth lens L14;

[0200] d28: an on-axis distance from the exit side surface of the fourteenth lens L14 to the object side surface of the fifteenth lens L15;

[0201] d29: an on-axis distance of the fifteenth lens L15;

[0202] d30: an on-axis distance from the exit side surface of the fifteenth lens L15 to the object side surface of the sixteenth lens L16;

[0203] d31: an on-axis thickness of the sixteenth lens L16;

[0204] d32: an on-axis distance from the exit side surface of the sixteenth lens L16 to the object side surface of the seventeenth lens L17;

[0205] d33: an on-axis thickness of the seventeenth lens L17;

[0206] d34: an on-axis distance from the exit side surface of the seventeenth lens L17 to the object side surface of the eighteenth lens L18;

[0207] d35: an on-axis thickness of the eighteenth lens L18;

[0208] d36: an on-axis distance from the exit side surface of the eighteenth lens L18 to the object plane;

[0209] nd: a refractive index of the d line (the d line is green light having a wavelength of 555 nm);

[0210] nd1: a refractive index of the d line of the first lens L1;

[0211] nd2: a refractive index of the d line of the second lens L2;

[0212] nd3: a refractive index of the d line of the third lens L3;

[0213] nd4: a refractive index of the d line of the fourth lens L4;

[0214] nd5: a refractive index of the d line of the fifth lens L5;

[0215] nd6: a refractive index of the d line of the sixth lens L6;

[0216] nd7: a refractive index of the d line of the seventh lens L7;

[0217] nd8: a refractive index of the d line of the eighth lens L8;

[0218] nd9: refractive index of d-line of the ninth lens L9;

[0219] nd10: refractive index of d-line of the tenth lens L10;

[0220] nd11: refractive index of d-line of the eleventh lens L11;

[0221] nd12: refractive index of d-line of the twelfth lens L12;

[0222] nd13: refractive index of d-line of the thirteenth lens L13;

[0223] nd14: refractive index of d-line of the fourteenth lens L14;

[0224] nd15: refractive index of d-line of the fifteenth lens L15;

[0225] nd16: refractive index of d-line of the sixteenth lens L16;

[0226] nd17: refractive index of d-line of the seventeenth lens L17;

[0227] nd18: refractive index of d-line of the eighteenth lens L18;

[0228] vd: Abbe number;

[0229] vd1: Abbe number of the first lens L1;

[0230] vd2: Abbe number of the second lens L2;

[0231] vd3: Abbe number of the third lens L3;

[0232] vd4: Abbe number of the fourth lens L4;

[0233] vd5: Abbe number of the fifth lens L5;

[0234] vd6: Abbe number of the sixth lens L6;

[0235] vd7: Abbe number of the seventh lens L7;

[0236] vd8: Abbe number of the eighth lens L8;

[0237] vd9: Abbe number of the ninth lens L9;

[0238] vd10: Abbe number of the tenth lens L10;

[0239] vd11: Abbe number of the eleventh lens L11;

[0240] vd12: Abbe number of the twelfth lens L12;

[0241] vd13: Abbe number of the thirteenth lens L13;

[0242] vd14: Abbe number of the fourteenth lens L14;

[0243] vd15: Abbe number of the fifteenth lens L15;

[0244] vd16: Abbe number of the sixteenth lens L16;

[0245] vd17: Abbe number of the seventeenth lens L17;

[0246] vd18: Abbe number of the eighteenth lens L18.

[0247] In addition, in the following Table 5, the values corresponding to the parameters defined in the conditional expressions of the various parameters in the first embodiment are also listed.

[0248] Fig. 2 shows the field curvature and distortion diagrams of light with a wavelength of 588 nm after passing through the microscope objective 10 of the first embodiment, the field curvature S of Fig. 2 is the sagittal field curvature, and T is the tangential field curvature; Fig. 3 shows the magnification chromatic aberration diagrams of wavelengths of 500 nm, 588 nm, 685 nm, 770 nm and 830 nm after passing through the microscope objective 10 of the first embodiment; Fig. 4 shows the axial aberration diagrams of wavelengths of 500 nm, 588 nm, 685 nm, 770 nm and 830 nm after passing through the microscope objective 10 of the first embodiment.

[0249] As shown in Table 5, the first embodiment satisfies each conditional expression.

[0250] In the present embodiment, the entrance pupil diameter of the microscope objective 10 is 15.202 mm, the full field image height is 0.65 mm, the working distance WD is 1.38 mm, and the numerical aperture NA is 0.85. The microscope objective 10 can control the light path between the lenses, help the smooth transition of the outgoing light, make the lens structure compact, control the total length of the microscope objective 10 while ensuring that the imaging range reaches the expected state, make the microscope objective 10 have a large numerical aperture, ensure that the light has sufficient converging power, and have excellent optical performance, meet the design requirements of low distortion, 20 times magnification, long working distance.

[0251] Second Embodiment:

[0252] Fig. 5 is a structural diagram of the microscope objective 20 in the second embodiment, the second embodiment is basically the same as the first embodiment, the symbol meanings are the same as the first embodiment, and only the different points are listed below.

[0253] Table 2 shows the design data of the microscope objective 20 of the second embodiment of the present application.

[0254] Table 2

[0255] In addition, in the following Table 5, the values corresponding to the parameters specified in the conditional expressions for the various parameters in the second embodiment are also listed.

[0256] Figure 6 shows the field curvature and distortion of light having a wavelength of 588 nm after passing through the microscope objective 20 of the second embodiment. The field curvature S in Figure 6 is the sagittal field curvature and T is the tangential field curvature. Figure 7 shows the lateral chromatic aberration of light having wavelengths of 500 nm, 588 nm, 685 nm, 770 nm and 830 nm after passing through the microscope objective 20 of the second embodiment. Figure 8 shows the axial chromatic aberration of light having wavelengths of 500 nm, 588 nm, 685 nm, 770 nm and 830 nm after passing through the microscope objective 20 of the second embodiment.

[0257] As shown in Table 5, the second embodiment satisfies the conditional expressions.

[0258] In the present embodiment, the entrance pupil diameter of the microscope objective 20 is 15.211 mm, the full field image height is 0.65 mm, the working distance WD is 1.30 mm and the numerical aperture NA is 0.85. The microscope objective 20 is able to control the path of the light between the lenses, facilitates smooth transition of the exiting light, makes the lens structure compact, controls the overall length of the microscope objective 20 while ensuring that the imaging range reaches the desired state, makes the microscope objective 20 have a large numerical aperture, ensures that the light has sufficient converging ability, and has excellent optical performance, satisfying the design requirements of bottom distortion, 20x magnification and long working distance.

[0259] Third Embodiment:

[0260] Figure 9 is a schematic diagram of the structure of the microscope objective 30 in the third embodiment. The third embodiment is substantially the same as the first embodiment, and the symbols have the same meanings as in the first embodiment. Only the differences are listed below.

[0261] In the present embodiment, the exit side surface of the third lens L3 is convex at the paraxial region;

[0262] The object side surface of the fourth lens L4 is convex at the paraxial region;

[0263] The exit side surface of the fifth lens L5 is concave at the paraxial region;

[0264] The exit side surface of the seventh lens L7 is concave at the paraxial region;

[0265] The object side surface of the twelfth lens L12 is convex at the paraxial region;

[0266] The object side surface of the thirteenth lens L13 is convex at the paraxial region;

[0267] Table 3 shows the design data of the microscope objective 30 of the third embodiment.

[0268]

Table 3

[0269] In addition, in the subsequent Table 5, the values corresponding to the parameters specified in the conditional expressions of the various parameters in the third embodiment are also listed.

[0270] Figure 10 shows the field curvature and distortion diagrams of the light with a wavelength of 588 nm after passing through the microscope objective 30 of the third embodiment, the field curvature S of Figure 10 is the sagittal field curvature, and T is the tangential field curvature; Figure 11 shows the magnification chromatic aberration diagrams of wavelengths of 500 nm, 588 nm, 685 nm, 770 nm and 830 nm after passing through the microscope objective 30 of the third embodiment; and Figure 12 shows the axial aberration diagrams of wavelengths of 500 nm, 588 nm, 685 nm, 770 nm and 830 nm after passing through the microscope objective 30 of the third embodiment.

[0271] As shown in Table 5, the third embodiment satisfies each conditional expression.

[0272] In the present embodiment, the entrance pupil diameter of the microscope objective 30 is 15.301 mm, the full field image height is 0.65 mm, the working distance WD is 1.30 mm, and the numerical aperture NA is 0.85. The microscope objective 30 can control the light path between the lenses, help the smooth transition of the outgoing light, make the lens structure compact, control the total length of the microscope objective 30 while ensuring that the imaging range reaches the expected state, make the microscope objective 30 have a large numerical aperture, ensure that the light has sufficient converging power, and have excellent optical performance, meeting the design requirements of low distortion, 20 times magnification, and long working distance.

[0273] Fourth Embodiment:

[0274] Figure 13 is a structural diagram of the microscope objective 40 in the fourth embodiment, which is basically the same as the first embodiment, and the symbol meanings are the same as the first embodiment. Only the different points are listed below.

[0275] In the present embodiment, the object side surface of the fourth lens L4 is convex at the paraxial region;

[0276] The exit side surface of the fifth lens L5 is concave at the paraxial region;

[0277] The exit side surface of the seventh lens L7 is concave at the paraxial region;

[0278] The object side surface of the thirteenth lens L13 is convex at the paraxial region.

[0279] Table 4 shows the design data of the microscope objective 40 of the fourth embodiment of the present application.

[0280]

Table 4

[0281] In addition, in the subsequent Table 5, the values corresponding to the parameters specified in the conditional expressions of the various parameters and conditions in the fourth embodiment are also listed.

[0282] Fig. 14 shows the field curvature and distortion diagrams of light with a wavelength of 555 nm after passing through the microscope objective 40 of the fourth embodiment, wherein the field curvature S is the sagittal field curvature and T is the tangential field curvature; Fig. 15 shows the magnification chromatic aberration diagrams of light with wavelengths of 500 nm, 588 nm, 685 nm, 770 nm and 830 nm after passing through the microscope objective 40 of the fourth embodiment; and Fig. 16 shows the axial chromatic aberration diagrams of light with wavelengths of 500 nm, 588 nm, 685 nm, 770 nm and 830 nm after passing through the microscope objective 40 of the fourth embodiment.

[0283] As shown in Table 5, the fourth embodiment satisfies the conditional expressions.

[0284] In the present embodiment, the entrance pupil diameter of the microscope objective 40 is 15.302 mm, the full field image height is 0.65 mm, the working distance WD is 1.30 mm, and the numerical aperture NA is 0.85. The microscope objective 40 can control the light path between the lenses, help the smooth transition of the outgoing light, make the lens structure compact, control the total length of the microscope objective 40 under the condition of ensuring the imaging range to reach the expected state, make the microscope objective 40 have a large numerical aperture, ensure that the light has sufficient converging ability, and have excellent optical performance, meet the design requirements of low distortion, 20 times magnification, long working distance.

[0285] Table 5 lists the numerical values corresponding to the conditional expressions in the comparative embodiments according to the above conditions.

[0286]

Table 5

[0287] The microscope objective provided by the embodiments of the present application is described in detail above, and the principles and embodiments of the present application are described by applying specific examples in this paper. The above description of the embodiments is only used to help understand the idea of the present application, and there will be changes in specific embodiments and application scope. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A microscope objective composed of, in order from an exit side to an object side, 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; a focal length of the microscope objective being f, a combined focal length of the first lens and the second lens being f1_2, a focal length of the third lens being f3, a combined focal length of the fourteenth lens, the fifteenth lens, and the sixteenth lens being f14_15_16, a combined focal length of the seventeenth lens and the eighteenth lens being f17_18, an on-axis thickness of the seventeenth lens being d33, an on-axis thickness of the eighteenth lens being d35, an on-axis distance from an object plane of the microscope objective to an exit surface of the first lens being TTL, an image height of the microscope objective being IH, and satisfying the following relationships: -3.10≤f1_2 / f3≤-1.80; 3.40≤f14_15_16 / f≤7.00; 4.00≤f17_18 / (d33+d35)≤120.00; 0.08≤IH*f / TTL≤0.

09.

2. The microscope objective according to claim 1, wherein a radius of curvature of an exit surface of the tenth lens being R19, a radius of curvature of an object side surface of the tenth lens being R20, and satisfying the following relationship: -1.60≤R19 / R20≤-2.

50.

3. The microscope objective according to claim 1, wherein an on-axis distance from the object plane to an object side surface of the eighteenth lens being WD, a numerical aperture of the microscope objective being NA, and satisfying the following relationship: WD*NA≥1.

10.

4. The microscope objective according to claim 1, wherein an exit surface of the first lens being convex at a paraxial region, an object side surface of the first lens being convex at the paraxial region; a radius of curvature of the exit surface of the first lens being R1, a radius of curvature of the object side surface of the first lens being R2, an on-axis thickness of the first lens being d1, and satisfying the following relationships: -1.39≤(R1+R2) / (R1-R2)≤-0.24; 0.03≤d1 / TTL≤0.

10.

5. The microscope objective according to claim 1, wherein an exit surface of the second lens being concave at a paraxial region, an object side surface of the second lens being concave at the paraxial region; a radius of curvature of the exit surface of the second lens being R3, a radius of curvature of the object side surface of the second lens being R4, an on-axis thickness of the second lens being d3, and satisfying the following relationships: 0.15≤(R3+R4) / (R3-R4)≤1.13; 0.01≤d3 / TTL≤0.

06.

6. The microscope objective according to claim 1, wherein the object side surface of the first lens and the exit surface of the second lens being cemented to constitute a combined lens having a positive refractive power, and satisfying the following relationship: 1.93≤f1_2 / f≤8.

42.

7. The microscope objective according to claim 1, wherein The object side surface of the third lens is concave at the paraxial region; the radius of curvature of the exit side surface of the third lens is R5, the radius of curvature of the object side surface of the third lens is R6, the on-axis thickness of the third lens is d5, and the following relationships are satisfied: 0.15≤(R5+R6) / (R5-R6)≤1.57; 0.01≤d5 / TTL≤0.03; -4.19≤f3 / f≤-1.

24.

8. The microscope objective according to claim 1, wherein The exit side surface of the fourth lens is concave at the paraxial region; the radius of curvature of the exit side surface of the fourth lens is R7, the radius of curvature of the object side surface of the fourth lens is R8, the on-axis thickness of the fourth lens is d7, and the following relationships are satisfied: -2.94≤(R7+R8) / (R7-R8)≤-0.12; 0.01≤d7 / TTL≤0.

06.

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

15.

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

03.

11. The microscope objective according to claim 1, wherein The object side surface of the fourth lens is cemented with the exit side surface of the fifth lens, and the object side surface of the fifth lens is cemented with the exit side surface of the sixth lens to form a combined lens with negative refractive power, the combined focal length of the fourth lens, the fifth lens, and the sixth lens is f4_5_6, and the following relationship is satisfied: -7.70≤f4_5_6 / f≤-1.

41.

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

34.

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

16.

14. The microscope objective according to claim 1, wherein An exit side surface of the ninth lens is concave at the paraxial region, an object side surface of the ninth lens is convex at the paraxial region; a curvature radius of the exit side surface of the ninth lens is R17, a curvature radius of the object side surface of the ninth lens is R18, an on-axis thickness of the ninth lens is d17, and the following relations are satisfied: -5.69≤(R17+R18) / (R17-R18)≤-0.82; 0.01≤d17 / TTL≤0.

04.

15. The microscope objective according to claim 1, wherein, An object side surface of the eighth lens and an exit side surface of the ninth lens are cemented to constitute a combined lens with positive refractive power, a combined focal length of the eighth lens and the ninth lens is f8_9, and the following relation is satisfied: 4.08≤f8_9 / f≤84.

27.

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

26.

17. The microscope objective according to claim 1, wherein An exit side surface of the eleventh lens is convex at the paraxial region, an object side surface of the eleventh lens is convex at the paraxial region; a curvature radius of the exit side surface of the eleventh lens is R21, a curvature radius of the object side surface of the eleventh lens is R22, an on-axis thickness of the eleventh lens is d21, and the following relations are satisfied: 0.02≤(R21+R22) / (R21-R22)≤1.02; 0.03≤d21 / TTL≤0.

13.

18. The microscope objective according to claim 1, wherein, An exit side surface of the twelfth lens is concave at the paraxial region; a curvature radius of the exit side surface of the twelfth lens is R23, a curvature radius of the object side surface of the twelfth lens is R24, an on-axis thickness of the twelfth lens is d23, and the following relations are satisfied: -2.18≤(R23+R24) / (R23-R24)≤-0.29; 0.01≤d23 / TTL≤0.

04.

19. The microscope objective according to claim 1, wherein, An object side surface of the eleventh lens and an exit side surface of the twelfth lens are cemented to constitute a combined lens with negative refractive power, a combined focal length of the eleventh lens and the twelfth lens is f11_12, and the following relation is satisfied: -879.88≤f11_12 / f≤-5.

21.

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

42.

21. The microscope objective according to claim 1, wherein An exit side surface of the fourteenth lens is convex at a paraxial region, and an object side surface of the fourteenth lens is convex at a paraxial region; a curvature radius of the exit side surface of the fourteenth lens is R27, a curvature radius of the object side surface of the fourteenth lens is R28, an on-axis thickness of the fourteenth lens is d27, and the following relations are satisfied: -1.06≤(R27+R28) / (R27-R28)≤-0.27; 0.04≤d27 / TTL≤0.

13.

22. The microscope objective according to claim 1, wherein An exit side surface of the fifteenth lens is concave at a paraxial region, and an object side surface of the fifteenth lens is concave at a paraxial region; a curvature radius of the exit side surface of the fifteenth lens is R29, a curvature radius of the object side surface of the fifteenth lens is R30, an on-axis thickness of the fifteenth lens is d29, and the following relations are satisfied: -0.05≤(R29+R30) / (R29-R30)≤0.98; 0.01≤d29 / TTL≤0.

03.

23. The microscope objective according to claim 1, wherein An exit side surface of the sixteenth lens is convex at a paraxial region, and an object side surface of the sixteenth lens is convex at a paraxial region; a curvature radius of the exit side surface of the sixteenth lens is R31, a curvature radius of the object side surface of the sixteenth lens is R32, an on-axis thickness of the sixteenth lens is d31, and the following relations are satisfied: -1.45≤(R31+R32) / (R31-R32)≤-0.29; 0.02≤d31 / TTL≤0.

09.

24. The microscope objective of claim 1, wherein, The object side surface of the fourteenth lens and the exit side surface of the fifteenth lens are cemented, and the object side surface of the fifteenth lens and the exit side surface of the sixteenth lens are cemented to form a combined lens having positive refractive power.

25. The microscope objective of claim 1, wherein, An exit side surface of the seventeenth lens is convex at a paraxial region, and an object side surface of the seventeenth lens is convex at a paraxial region; a curvature radius of the exit side surface of the seventeenth lens is R33, a curvature radius of the object side surface of the seventeenth lens is R34, an on-axis thickness of the seventeenth lens is d33, and the following relations are satisfied: -1.08≤(R33+R34) / (R33-R34)≤-0.17; 0.02≤d33 / TTL≤0.

08.

26. The microscope objective of claim 1, wherein, The exit side surface of the eighteenth lens is concave at the paraxial region, and the object side surface of the eighteenth lens is concave at the paraxial region; the radius of curvature of the exit side surface of the eighteenth lens is R35, the radius of curvature of the object side surface of the eighteenth lens is R36, the on-axis thickness of the eighteenth lens is d35, and the following relationships are satisfied: 0.25≤(R35+R36) / (R35-R36)≤0.93; 0.01≤d35 / TTL≤0.

04.

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

Images