Imaging lens

Abstract

The invention relates to an imaging lens which sequentially comprises a first lens group with positive focal power, a second lens group with negative focal power and a third lens group with positive focal power from an object side to an image side along an optical axis, the first lens group and the third lens group are fixed lens groups, and the second lens group is a focusing group; the first lens group comprises a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power and a fourth lens with negative focal power; the second lens group comprises a fifth lens with positive focal power and a sixth lens with negative focal power; the third lens group comprises a seventh lens, an eighth lens and a ninth lens, wherein the seventh lens and the eighth lens are opposite in focal power, and the ninth lens is positive in focal power. The effective focal length FG2 of the second lens group and the total effective focal length FI of the imaging lens when the object distance is 0.3 m meet the condition that FG2 / FI is larger than or equal to-2.4 and smaller than or equal to-0.3. The imaging lens at least has one of the characteristics of wide object distance, low distortion, high illumination, no virtual focus at high temperature, athermalization and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial lenses, and in particular to an imaging lens with wide object distance, low distortion, high illumination, no false focus at high temperature, and no thermalization. Background Art

[0002] Industrial lenses are indispensable components in machine vision systems. They play a key role in applications such as automated inspection, quality control, measurement, and identification.

[0003] The industrial lenses on the market today still have the following shortcomings:

[0004] 1. The existing lens has a narrow focus distance range and does not meet the requirements of multi-scene use;

[0005] 2. The existing lens has large distortion, which causes the image to be distorted to a large extent;

[0006] 3. The existing lens has low illumination, which makes the image darker and the color saturation lower;

[0007] 4. When existing lenses are used to capture and observe objects at a long distance, the image clarity is low;

[0008] 5. The focus of existing lenses drifts in high and low temperature environments, and the imaging effect is seriously affected by the environment.

[0009] Therefore, it has become a market development trend to design an imaging lens that meets at least one of the following characteristics: wide focus distance range, low distortion, high illumination, no out-of-focus at high temperature, and no thermalization. Summary of the invention

[0010] In order to solve the above problems existing in the prior art, the object of the present invention is to provide an imaging lens having at least one of the characteristics of wide object distance, low distortion, high illumination, no defocusing at high temperature, and no thermalization.

[0011] To achieve the above-mentioned object, the present invention provides an imaging lens, which comprises, in order from the object side to the image side of the optical axis: a first lens group with positive optical power, a second lens group with negative optical power, and a third lens group with positive optical power, wherein the first lens group and the third lens group are fixed lens groups, and the second lens group is a focus adjustment group that moves along the optical axis of the imaging lens;

[0012] The first lens group includes, in sequence: a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power, and a fourth lens with negative optical power, a total of four lenses;

[0013] The second lens group includes in sequence: a fifth lens with positive optical power and a sixth lens with negative optical power, a total of two lenses;

[0014] The third lens group includes, in sequence: a seventh lens, an eighth lens and a ninth lens with positive optical power, a total of three lenses; the optical power of the seventh lens and the eighth lens are opposite.

[0015] According to a technical solution of the present invention, the object side surface of the first lens is convex, the image side surface of the second lens is concave, the third lens is a convex-convex lens; and the object side surface of the fourth lens is concave.

[0016] According to a technical solution of the present invention, the image side surface of the fifth lens is a convex surface; and the sixth lens is a concave-concave lens.

[0017] According to a technical solution of the present invention, the object-side surface of the ninth lens is a convex surface.

[0018] According to a technical solution of the present invention, the third lens and the fourth lens form a doublet lens, and the fifth lens and the sixth lens form a doublet lens.

[0019] According to a technical solution of the present invention, the effective focal length FG1 of the first lens group and the total effective focal length FI of the imaging lens when the object distance is 0.3 m satisfy the following relationship: 0.8≤FG1 / FI≤1.7.

[0020] According to a technical solution of the present invention, the effective focal length FG3 of the third lens group and the total effective focal length FI of the imaging lens when the object distance is 0.3 m satisfy the following relationship: 0.5≤FG3 / FI≤1.1.

[0021] According to a technical solution of the present invention, the focus moving distance d2 of the second lens group within the object distance variation range and the effective focal length FG2 of the second lens group satisfy the following relationship: -5.6≤FG2 / d2≤-3.6.

[0022] According to a technical solution of the present invention, the air spacing distance d23 between the second lens and the third lens on the optical axis and the effective focal length FG1 of the first lens group satisfy the following relationship: 2.5≤FG1 / d23≤120.

[0023] According to a technical solution of the present invention, the air spacing distance d23 between the second lens and the third lens on the optical axis and the effective focal length FG1 of the first lens group satisfy the following relationship: 2.5≤FG1 / d23≤9.

[0024] According to a technical solution of the present invention, the combined effective focal length F34 of the third lens and the fourth lens and the effective focal length FG1 of the first lens group satisfy the following relationship: 0.2≤F34 / FG1≤1.1.

[0025] According to a technical solution of the present invention, the effective focal length F1 of the first lens and the effective focal length FG1 of the first lens group satisfy the following relationship: 0.95≤FG1 / F1≤1.7.

[0026] According to a technical solution of the present invention, the effective focal length FG1 of the first lens group and the effective focal length F2 of the second lens group satisfy the following relationship: -2.85≤FG1 / F2≤-1.

[0027] According to a technical solution of the present invention, the effective focal length F4 of the fourth lens and the effective focal length F3 of the third lens satisfy the following relationship: -3.4≤F4 / F3≤-1.6.

[0028] According to a technical solution of the present invention, the Abbe number Vd3 of the third lens and the effective focal length F3 of the third lens satisfy the following relationship: 2.4≤Vd3 / F3≤4.

[0029] According to a technical solution of the present invention, the effective focal length F5 of the fifth lens and the effective focal length F6 of the sixth lens satisfy the following relationship: -2.8≤F5 / F6≤-1.3.

[0030] According to a technical solution of the present invention, the effective focal length FG3 of the third lens group and the effective focal length F7 of the seventh lens, the effective focal length F8 of the eighth lens and the effective focal length F9 of the ninth lens satisfy the following relationship: 0.8≤FG3 / (F7+F8+F9)≤1.9.

[0031] According to a technical solution of the present invention, the maximum effective light aperture DG1_MAX of the lenses from the first lens to the ninth lens and the total effective focal length FI of the imaging lens when the object distance is 0.3m satisfy the following relationship: 4.87≤FI / DG1_MAX≤5.6.

[0032] According to a technical solution of the present invention, the maximum effective light aperture DG1_MAX of the lenses from the first lens to the ninth lens and the total length TTL of the optical system of the imaging lens satisfy the following relationship: 9≤TTL / DG1_MAX≤10.4.

[0033] According to a technical solution of the present invention, the back focal length BFL of the imaging lens and the total optical system length TTL of the imaging lens satisfy the following relationship: 0.3≤BFL / TTL≤0.5.

[0034] According to a technical solution of the present invention, the total optical system length TTL of the imaging lens and the total effective focal length FI of the imaging lens when the object distance is 0.3 m satisfy the following relationship: 1.6≤TTL / FI≤2.

[0035] According to a technical solution of the present invention, the Abbe number Vd6 of the sixth lens, the Abbe number Vd5 of the fifth lens and the total effective focal length FI of the imaging lens when the object distance is 0.3m satisfy the following relationship: 0.15≤(Vd6-Vd5) / FI≤0.75.

[0036] According to a technical solution of the present invention, the total effective focal length FI of the imaging lens when the object distance is 0.3m and the effective focal length FII of the imaging lens when the object distance is infinity satisfy the following relationship: 1≤FI / FII≤1.5.

[0037] According to a technical solution of the present invention, the effective focal length FG2 of the second lens group and the total effective focal length FI of the imaging lens when the object distance is 0.3m satisfy the following relationship: -2.4≤FG2 / FI≤-0.3.

[0038] According to a technical solution of the present invention, the imaging lens satisfies at least one of the following conditions:

[0039] 0.88≤FG1 / FI≤1.63,

[0040] -2.2≤FG2 / FI≤-0.5,

[0041] 0.95≤FG3 / FI≤0.65,

[0042] -5.4≤FG2 / d2≤-3.9,

[0043] 2.6≤FG1 / d23≤8.55,

[0044] 0.2≤F34 / FG1≤1.05,

[0045] 1≤FG1 / F1≤1.6,

[0046] -2.7≤FG1 / F2≤-1.2,

[0047] -3.2≤F4 / F3≤-1.8,

[0048] 2.55≤Vd3 / F3≤3.85,

[0049] -2.65≤F5 / F6≤-1.5,

[0050] 1.0≤FG3 / (F7+F8+F9)≤1.85,

[0051] 4.9≤FI / DG1_MAX≤5.5,

[0052] 9.2≤TTL / DG1_MAX≤10.3,

[0053] 0.3≤BFL / TTL≤0.4,

[0054] 1.7≤TTL / FI≤2,

[0055] 0.2≤(Vd6-Vd5) / FI≤0.7,

[0056] 1≤FI / FII≤1.25,

[0057] Wherein, FI is the total effective focal length of the imaging lens when the object distance is 0.3 m, FG1 is the effective focal length of the first lens group, FG2 is the effective focal length of the second lens group, FG3 is the effective focal length of the third lens group, d2 is the focus moving distance of the second lens group within the object distance variation range, d23 is the air spacing distance between the second lens and the third lens on the optical axis, F34 is the combined effective focal length of the third lens and the fourth lens, F1 is the effective focal length of the first lens, F2 is the effective focal length of the second lens, F3 is the effective focal length of the third lens, and F4 is the effective focal length of the fourth lens. wherein, Vd3 is the Abbe number of the third lens, F5 is the effective focal length of the fifth lens, F6 is the effective focal length of the sixth lens, F7 is the effective focal length of the seventh lens, F8 is the effective focal length of the eighth lens, F9 is the effective focal length of the ninth lens, DG1_MAX is the maximum effective aperture of the lenses from the first lens to the ninth lens, TTL is the total length of the optical system of the imaging lens, BFL is the back focal length of the imaging lens, Vd6 is the Abbe number of the sixth lens, Vd5 is the Abbe number of the fifth lens, and FII is the effective focal length of the imaging lens when the object distance is infinity.

[0058] According to the solution of the present invention, by setting the number and focal length of imaging lenses, the ultra-wide-angle lens has at least one of the following beneficial effects: wide working distance (clear focus can be achieved from 0.3m to infinity object distance), low distortion (absolute value of optical distortion ≤0.75%), high illumination (relative illumination RI ≥70%), and miniaturization (total optical length TTL ≤79mm); the diaphragm is placed at the rear and the aperture is constant (FNO=3.0); the problem of focus drift in high and low temperature environments is solved, and the lens can be kept in a temperature range of -40°C to 80°C without being out of focus, achieving athermalization of the lens, and being suitable for various high and low temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0060] Figure 1 Schematic diagram of the structure of an imaging lens according to Embodiment 1 of the present invention;

[0061] Figure 2 Schematic diagram of distortion of the imaging lens of Example 1 of the present invention when the object distance is 0.3 m;

[0062] Figure 3 Schematic diagram of distortion of the imaging lens of Embodiment 1 of the present invention when the object distance is infinite;

[0063] Figure 4 Schematic diagram of the structure of an imaging lens according to Embodiment 2 of the present invention;

[0064] Figure 5 Schematic diagram of distortion of the imaging lens of Example 2 of the present invention when the object distance is 0.3m;

[0065] Figure 6 Schematic diagram of distortion of the imaging lens of Embodiment 2 of the present invention when the object distance is infinite;

[0066] Figure 7 Schematic diagram of the structure of an imaging lens according to Embodiment 3 of the present invention;

[0067] Figure 8 Schematic diagram of distortion of the imaging lens of Example 3 of the present invention when the object distance is 0.3m;

[0068] Fig. 9 FIG. 4 is a schematic diagram of distortion of the imaging lens of Embodiment 3 of the present invention when the object distance is infinite.

[0069] Fig.10 Schematic diagram of the structure of an imaging lens according to Embodiment 4 of the present invention;

[0070] Fig.11 Schematic diagram of distortion of the imaging lens of Example 4 of the present invention when the object distance is 0.3 m;

[0071] Fig.12 Schematic diagram of distortion of the imaging lens of Embodiment 4 of the present invention when the object distance is infinite;

[0072] Fig.13 Schematic diagram of the structure of an imaging lens according to Embodiment 5 of the present invention;

[0073] Fig.14 Schematic diagram of distortion of the imaging lens of Example 5 of the present invention when the object distance is 0.3 m;

[0074] Fig.15 FIG. 4 is a schematic diagram of distortion of the imaging lens of Embodiment 5 of the present invention when the object distance is infinite. DETAILED DESCRIPTION

[0075] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0076] It should be noted that in this specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present application, the first lens discussed below may also be referred to as the second lens or the first lens.

[0077] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0078] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side of the lens, and the surface of each lens closest to the imaging plane is called the image side of the lens.

[0079] It should also be understood that the terms "comprises", "including", "having", "includes" and / or "comprising", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0080] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as those commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0081] It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The following examples only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for those of ordinary skill in the art, without departing from the concept of the present application, several variations and improvements can also be made, which all belong to the protection scope of the present application.

[0082] like Figures 1 to 15 As shown, an embodiment of the present invention provides an imaging lens, which includes, in sequence along the direction from the object side to the image side of the optical axis: a first lens group G1 with positive optical focal length, a second lens group G2 with negative optical focal length, a third lens group G3 with positive optical focal length, an aperture STO, a parallel plate CG and an image plane IMA, the first lens group G1 and the third lens group are fixed lens groups, and the second lens group G2 is a focusing group that moves along the optical axis of the imaging lens.

[0083] Among them, the first lens group G1 is a fixed front group, and the first lens group G1 has positive focal length, which is conducive to converging the incident light into the optical system, effectively controlling the trend of the light, balancing the spherical aberration and coma generated by the optical system, compensating for the system chromatic aberration, and ensuring the resolution quality of the lens; at the same time, it effectively reduces the tolerance sensitivity of the optical system and improves the lens production yield.

[0084] The second lens group G2 is a focusing group, and the second lens group G2 has negative optical power, and moves along the optical axis from the image side to the object side. By changing the position of the second lens group on the optical axis, the lens working distance can support 0.3M to infinity, meeting the requirements of a larger range of working distances.

[0085] The third lens group G3 is a fixed rear group, and the third lens group G3 has positive focal power and is fixed in position relative to the image plane. It can effectively control the trend of light, make the light smoothly transition to the image plane, correct the astigmatism and field curvature of the optical system, reduce the tolerance sensitivity of the optical system, help to ensure the resolution quality of the lens, and improve the production yield; at the same time, it can also effectively compensate for the axial chromatic aberration of the optical system to ensure the color reproduction of the imaging picture.

[0086] In the embodiment of the present invention, along the direction from the object side to the image side of the optical axis, the first lens group G1 includes in sequence: a first lens L1, a second lens L2, a third lens L3 and a fourth lens L4, a total of four lenses.

[0087] The object-side surface of the first lens L1 is convex and has positive refractive power, which is conducive to converging incident light into the optical system.

[0088] The image side surface of the second lens L2 is concave and has negative optical power, which is beneficial to the divergence of light after passing through the second lens L2, effectively controlling the trend of light, so that the trend of light can better cooperate with the large-aperture third lens L3 and fourth lens L4; at the same time, it is also beneficial to reduce the distortion of the optical system, so that the absolute value of the optical distortion of the lens is ≤0.75%.

[0089] The third lens L3 is a convex-convex lens with positive power, the object side surface of the fourth lens L4 is concave and has negative power, the third lens L3 and the fourth lens L4 are set to match positive and negative power, and the aperture is large, which is conducive to the chromatic aberration correction of the optical system and improves the imaging performance of the telephoto lens. The third lens L3 and the fourth lens L4 can cooperate with each other to form a cemented lens, and when forming a double cemented lens, the tolerance sensitivity of the optical system can be effectively reduced, and the production yield of the lens can be improved.

[0090] In the embodiment of the present invention, along the direction from the object side to the image side of the optical axis, the second lens group G2 includes a fifth lens L5 and a sixth lens L6 in sequence, for a total of two lenses.

[0091] The image side surface of the fifth lens L5 is convex and has positive power; the sixth lens L6 is a concave-concave lens with negative power. The fifth lens L5 and the sixth lens L6 use a combination of positive and negative power lenses. At the same time, the fifth lens L5 can preferably use a high dispersion lens material, and the sixth lens L6 can preferably use a low dispersion lens material. Using materials with different dispersion coefficients can make the dispersions compensate each other, so as to achieve the purpose of eliminating position chromatic aberration, which is beneficial to improving the imaging performance of the telephoto lens. The fifth lens L5 and the sixth lens L6 can cooperate with each other to form a double-cemented lens group. When forming a double-cemented lens, the tolerance sensitivity of the optical system can be effectively reduced, and the production yield of the lens can be improved.

[0092] The third lens group G3 includes in sequence: a seventh lens L7, an eighth lens L8 and a ninth lens L9, a total of three lenses.

[0093] The seventh lens L7 and the eighth lens L8 have opposite optical powers, and the object side surface of the ninth lens L9 is convex and has positive optical power. By reasonably setting the optical powers of the seventh lens L7, the eighth lens L8 and the ninth lens L9, their positive-negative-positive or negative-positive-positive optical powers are matched with each other, which is conducive to the mutual compensation of positive and negative spherical aberrations, and at the same time corrects the system's astigmatism and field curvature, and improves the lens resolution; at the same time, effectively controls the trend of light, makes the light transition smoothly, and effectively reduces the tolerance sensitivity of the fixed rear group.

[0094] The seventh lens L7, the eighth lens L8 and the ninth lens L9 can be combined into a triplet lens or a combination of a single lens and a group of doublet lenses, which can effectively balance the axial chromatic aberration, improve the resolution of the lens, and effectively reduce the tolerance sensitivity of the fixed rear group, thereby improving the production yield.

[0095] The present invention adopts a constant aperture, and can keep the aperture constant in the object distance range from 0.3m to infinity during the focusing process, which is beneficial to ensuring that the resolution does not decrease and the imaging picture is transparent.

[0096] The present invention adopts a focusing lens structure of three lens groups of positive, negative and positive and one aperture, which can well meet the use requirements within the object distance range of 0.3m to infinity, and is also conducive to correcting field curvature and distortion, reducing the tolerance sensitivity of the system, eliminating system chromatic aberration, and reducing the generation of lens purple fringing. The reasonable matching of the group focal length enables the light to correct high-order aberrations to a great extent when passing through the lens smoothly, improving the imaging quality; at the same time, it is conducive to the focusing lens group to achieve continuous changes within the object distance range of 0.3m to infinity, compensate for the aberrations caused during the zoom movement, and effectively ensure the clarity of the image under different object distances.

[0097] In some embodiments of the present invention, the first lens L1 to the ninth lens L9 may be made of glass lens material or plastic lens, and the lens surface may be spherical or aspherical. An optical lens made of glass can suppress the deviation of the back focus of the imaging lens with temperature changes to improve the stability of the system; at the same time, the use of glass material can avoid the blurring of the lens imaging caused by high and low temperature changes in the use environment, which affects the normal use of the lens and is conducive to the athermalization of the lens; and it can also better correct the system chromatic aberration and improve the resolution of the lens. In some embodiments of the present invention, the first lens L1 to the ninth lens L9 are all made of glass lenses, and the imaging lens with a full glass design has a wide temperature range and can maintain stable optical performance in the range of -40°C to 85°C.

[0098] In some embodiments of the present invention, the effective focal length FG1 of the first lens group G1 and the total effective focal length FI of the imaging lens when the object distance is 0.3m satisfy the following relationship: 0.8≤FG1 / FI≤1.7, preferably, 0.88≤FG1 / FI≤1.63. Reasonable control of the ratio of the focal length FG1 of the first lens group G1 to the effective focal length FI of the imaging lens when the object distance is 0.3m is conducive to converging the incident light into the optical system, while effectively controlling the light trend, which is conducive to compensating the spherical aberration, coma and axial chromatic aberration of the optical system, and improving the imaging quality of the lens.

[0099] In some embodiments of the present invention, the effective focal length FG2 of the second lens group G2 and the total effective focal length FI of the imaging lens when the object distance is 0.3m satisfy the following relationship: -2.4≤FG2 / FI≤-0.3, preferably, -2.2≤FG2 / FI≤-0.5. By reasonably controlling the ratio of the effective focal length FG2 of the second lens group G2 to the total effective focal length FI of the imaging lens when the object distance is 0.3m, it is beneficial to make the lens working distance support 0.3m to infinity, meeting the requirements of a larger range of working distances.

[0100] In some embodiments of the present invention, the effective focal length FG3 of the third lens group G3 and the total effective focal length FI of the imaging lens when the object distance is 0.3m satisfy the following relationship: 0.5≤FG3 / FI≤1.1, preferably, 0.95≤FG3 / FI≤0.65. By reasonably controlling the ratio of the effective focal length FG3 of the third lens group G3 to the total effective focal length FI of the imaging lens when the object distance is 0.3m, the trend of light can be effectively controlled, the light can be smoothly transitioned to the image plane, the astigmatism and field curvature of the optical system can be corrected, the tolerance sensitivity of the optical system can be reduced, it is helpful to ensure the resolution quality of the lens and improve the production yield; at the same time, the axial chromatic aberration of the optical system can be effectively compensated to ensure the color reproduction of the imaging picture.

[0101] In some embodiments of the present invention, the focus moving distance d2 of the second lens group G2 within the object distance variation range and the effective focal length FG2 of the second lens group G2 satisfy the following relationship: -5.6≤FG2 / d2≤-3.6, preferably, -5.4≤FG2 / d2≤-3.9. By reasonably controlling the ratio of the effective focal length FG2 of the second lens group G2 to the focus moving distance d2 of the second lens group G2 within the object distance variation range, it is beneficial to reasonably control the moving distance of the second lens group G2 during focusing, so that it can meet the requirements of a larger range of working distances while effectively limiting the length of the imaging lens, thereby facilitating the miniaturization of the imaging lens and improving the focusing response speed of the lens; it also effectively ensures the tolerance sensitivity of the optical system.

[0102] In some embodiments of the present invention, the air distance d23 between the second lens L2 and the third lens L3 on the optical axis and the effective focal length FG1 of the first lens group G1 satisfy the following relationship: 2.5≤FG1 / d23≤120, preferably, 2.5≤FG1 / d23≤9, further preferably, 2.6≤FG1 / d23≤8.55. Reasonable control of the air distance d23 between the second lens L2 and the third lens L3 in the first lens group G1 on the optical axis can effectively control the trend of light, reduce the deflection angle of light entering the object side of the third lens L3, and make the trend of light better cooperate with the large-diameter third lens L3 and the fourth lens L4.

[0103] In some embodiments of the present invention, the combined effective focal length F34 of the third lens L3 and the fourth lens L4 and the effective focal length FG1 of the first lens group G1 satisfy the following relationship: 0.2≤F34 / FG1≤1.1, preferably, 0.2≤F34 / FG1≤1.05. By rationally controlling the ratio of the combined effective focal length F34 of the third lens L3 and the fourth lens L4 to the effective focal length FG1 of the first lens group G1, it is beneficial to correct the chromatic aberration of the optical system, introduce positive spherical aberration to compensate for the spherical aberration of the optical system, and improve the imaging performance of the telephoto lens; it can also effectively reduce the residual thermal difference of the optical system and ensure the athermalization of the lens.

[0104] In some embodiments of the present invention, the effective focal length F1 of the first lens L1 and the effective focal length FG1 of the first lens group G1 satisfy the following relationship: 0.95≤FG1 / F1≤1.7, preferably, 1≤FG1 / F1≤1.6. By properly controlling the ratio of the effective focal length FG1 of the first lens group G1 to the effective focal length F1 of the first lens L1, it is helpful to converge the incident light into the optical system, expand the field of view, and make the field of view meet the design requirements.

[0105] In some embodiments of the present invention, the effective focal length FG1 of the first lens group G1 and the effective focal length F2 of the second lens L2 satisfy the following relationship: -2.85≤FG1 / F2≤-1, preferably, -2.7≤FG1 / F2≤-1.2. By properly controlling the effective focal length FG1 of the first lens group G1 and the effective focal length F2 of the second lens L2, it is beneficial for the light to diverge after passing through the second lens L2, effectively controlling the trend of the light, so that the trend of the light can better cooperate with the third lens L3 and the fourth lens L4 with a large aperture; at the same time, it is also beneficial to reduce the distortion of the optical system, so that the absolute value of the optical distortion of the lens is ≤0.75%.

[0106] In some embodiments of the present invention, the effective focal length F4 of the fourth lens L4 and the effective focal length F3 of the third lens L3 satisfy the following relationship: -3.4≤F4 / F3≤-1.6, preferably, -3.2≤F4 / F3≤-1.8. The two lenses are set to cooperate with positive and negative optical powers to effectively control the trend of light, which is beneficial to the convergence of light after passing through the third lens L3 and the fourth lens L4, which is beneficial to the chromatic aberration correction of the optical system and improves the imaging performance of the telephoto lens; and effectively reduces the tolerance sensitivity of the optical system and improves the production yield of the lens.

[0107] In some embodiments of the present invention, the Abbe number Vd3 of the third lens L3 and the effective focal length F3 of the third lens L3 satisfy the following relationship: 2.4≤Vd3 / F3≤4, preferably, 2.55≤Vd3 / F3≤3.85. Reasonable control of the ratio of the Abbe number Vd3 of the third lens L3 to its effective focal length F3 and the use of low-dispersion glass material for the third lens L3 are helpful in correcting system chromatic aberration; at the same time, it is also beneficial to ensure that the optical system is insensitive within the range of ambient temperature changes and object distance changes, effectively reduce the thermal difference residual of the optical system, and realize the athermalization of the lens, which is suitable for various environments.

[0108] In some embodiments of the present invention, the effective focal length F5 of the fifth lens L5 and the effective focal length F6 of the sixth lens L6 satisfy the following relationship: -2.8≤F5 / F6≤-1.3, preferably, -2.65≤F5 / F6≤-1.5. Reasonably controlling the ratio of the effective focal lengths of the fifth lens L5 and the sixth lens L6 and using a combination of positive and negative optical power lenses can effectively correct the chromatic aberration of the optical system within the range of object distance variation, while reducing the tolerance sensitivity of the optical system and improving the production yield of the lens.

[0109] In some embodiments of the present invention, the effective focal length FG3 of the third lens group G3 and the effective focal length F7 of the seventh lens L7, the effective focal length F8 of the eighth lens L8 and the effective focal length F9 of the ninth lens L9 satisfy the following relationship: 0.8≤FG3 / (F7+F8+F9)≤1.9, preferably, 1.0≤FG3 / (F7+F8+F9)≤1.85. Reasonable setting of the optical power of the seventh lens L7, the eighth lens L8 and the ninth lens L9 is conducive to the mutual compensation of positive and negative spherical aberrations, while correcting the astigmatism and field curvature of the system, and improving the lens resolution; at the same time, effectively controlling the trend of light, making the light transition smoothly, effectively reducing the tolerance sensitivity of the fixed rear group, and improving the production yield.

[0110] In some embodiments of the present invention, the maximum effective aperture DG1_MAX of the lens in the first lens L1 to the ninth lens L9 and the total effective focal length FI of the imaging lens when the object distance is 0.3m satisfy the following relationship: 4.87≤FI / DG1_MAX≤5.6, preferably, 4.9≤FI / DG1_MAX≤5.5. Reasonably controlling the ratio of the total effective focal length FI of the imaging lens when the object distance is 0.3m to the maximum effective aperture DG1_MAX in the first lens L1 to the ninth lens L9 and setting a larger aperture can help improve the chromatic aberration of the optical system and improve the imaging performance of the lens.

[0111] In some embodiments of the present invention, the maximum effective aperture DG1_MAX of the lens in the first lens L1 to the ninth lens L9 and the total length TTL of the optical system of the imaging lens satisfy the following relationship: 9≤TTL / DG1_MAX≤10.4, preferably, 9.2≤TTL / DG1_MAX≤10.3. By reasonably setting the ratio of the total length TTL of the optical system to the maximum effective aperture in the first lens L1 to the ninth lens L9, the maximum effective aperture and the total length of the optical system can be reasonably constrained and controlled, which is conducive to miniaturization of the lens, so that the total optical length TTL≤79mm.

[0112] In some embodiments of the present invention, the back focal length BFL of the imaging lens and the total length TTL of the optical system of the imaging lens satisfy the following relationship: 0.3≤BFL / TTL≤0.5, preferably, 0.3≤BFL / TTL≤0.4. On the basis of achieving miniaturization, by controlling the optical back focal length of the system, the back focal length of the lens is made longer, which helps to reserve space for the installation of optical elements, facilitates the assembly of the imaging lens, avoids interference, and improves the assembly yield of the imaging lens.

[0113] In some embodiments of the present invention, the total optical system length TTL of the imaging lens and the effective focal length FI of the imaging lens when the object distance is 0.3 m satisfy the following relationship: 1.6≤TTL / FI≤2, preferably, 1.7≤TTL / FI≤2. The ratio of the total optical system length TTL to the total effective focal length FI of the imaging lens when the object distance is 0.3 m is reasonably controlled within a specific range, so that the total length of the optical system is reasonably controlled on the basis of satisfying a certain focal length, which is conducive to miniaturization of the lens.

[0114] In some embodiments of the present invention, the Abbe number Vd6 of the sixth lens L6 and the Abbe number Vd5 of the fifth lens L5 satisfy the following relationship with the effective focal length FI of the imaging lens when the object distance is 0.3 m: 0.15≤(Vd6-Vd5) / FI≤0.75, preferably, 0.2≤(Vd6-Vd5) / FI≤0.7. By reasonably controlling the ratio of the difference in the Abbe numbers of the sixth lens L6 and the fifth lens L5 to the total effective focal length FI of the imaging lens when the object distance is 0.3 m, and using materials with different dispersion coefficients, the dispersions can be compensated for each other, thereby achieving the purpose of eliminating positional chromatic aberration, which is beneficial to improving the imaging performance of the telephoto lens; at the same time, it can also effectively reduce the tolerance sensitivity of the optical system and improve the production yield of the lens.

[0115] In some embodiments of the present invention, the effective focal length FI of the imaging lens when the object distance is 0.3 m and the effective focal length FII of the imaging lens when the object distance is infinity satisfy the following relationship: 1≤FI / FII≤1.5, preferably, 1≤FI / FII≤1.25, and the ratio of the effective focal lengths of the optical system when the object distance is 0.3 m and infinity is reasonably controlled. When the ratio value is smaller, it can effectively ensure that the change in the system field of view angle of the lens within the range of object distance change is smaller.

[0116] Five groups of specific embodiments are given below based on the above-mentioned configuration of the present invention to specifically illustrate the imaging lens according to the present invention. The imaging lens according to the present invention has a total of nine lenses, each cemented surface of the cemented lens is recorded as a surface, plus the aperture STO, the protective glass CG and the image surface IMA, a total of 18 or 19 surfaces. Among them, the aperture STO is set behind the image side surface of the ninth lens L9. For the convenience of description, each lens surface, the aperture STO and the protective glass CG are numbered S1, S2 to S18 or S1, S2 to S19.

[0117] The data of five groups of embodiments are shown in Table 1 below:

[0118]

[0119]

[0120] Table 1

[0121] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0122] Embodiment 1

[0123] Figure 1 Schematic diagram of the structure of an imaging lens according to Embodiment 1 of the present invention;

[0124] Figure 2Schematic diagram of distortion of the imaging lens of Example 1 of the present invention when the object distance is 0.3 m;

[0125] Figure 3 FIG. 4 is a schematic diagram of distortion of the imaging lens of Embodiment 1 of the present invention when the object distance is infinite.

[0126] In Embodiment 1, the first lens L1 is a convex-plano lens with positive optical power, the second lens L2 is a plano-concave lens with negative optical power, the third lens L3 is a convex-convex lens with positive optical power, the fourth lens L4 is a concave-convex lens with negative optical power, the fifth lens L5 is a concave-convex lens with positive optical power, the sixth lens L6 is a concave-concave lens with negative optical power, the seventh lens L7 is a convex-convex lens with positive optical power, the eighth lens L8 is a concave-concave lens with negative optical power, and the ninth lens L9 is a convex-convex lens with positive optical power.

[0127] The third lens L3 and the fourth lens L4, the fifth lens L5 and the sixth lens L6 form a doublet lens, the seventh lens L7, the eighth lens L8 and the ninth lens L9 form a triplet lens, and the aperture stop STO is arranged behind the object side surface of the ninth lens L9.

[0128] The first lens L1 to the ninth lens L9 are all made of glass lens material.

[0129] Table 2 lists the relevant parameters of each lens in the imaging lens of this embodiment, including: surface type, curvature radius R, thickness d, refractive index Nd and Abbe number Vd of the material.

[0130] Surface serial number Surface type Curvature radius R Thickness d Refractive index Nd Abbe number Vd S1 Spherical 32.562 2.440 1.883 39.22 S2 Spherical Infinity 0.500 S3 Spherical Infinity 0.800 1.581 40.92 S4 Spherical 17.483 14.390 S5 Spherical 23.787 4.610 1.593 66.99 S6 Spherical -17.221 0.700 1.603 38.01 S7 Spherical -97.862 T0 S8 Spherical -22.791 3.070 1.946 17.99 S9 Spherical -15.506 0.700 1.548 45.83 S10 Spherical 21.439 T1 S11 Spherical 35.661 2.380 2.001 29.13 S12 Spherical -37.04 0.700 1.741 27.76 S13 Spherical 12.52 3.100 1.593 66.99 S14 Spherical -37.311 0.500 S15(STO) Spherical Infinity 29.750 S16 Spherical Infinity 0.900 1.517 64.21 S17 Spherical Infinity 0.040 S18(IMA) Spherical Infinity -

[0131] Table 2

[0132] Table 3 lists the variable spacing values ​​between lens groups of the imaging lens of this embodiment when the object distance changes from 0.3M to infinity.

[0133] Surface number thickness When the object distance is 0.3M Object distance is infinite S7 T0 10.423 4.703 S10 T1 3.998 9.718

[0134] Table 3

[0135] In the first embodiment, the effective focal length FI of the imaging lens is 41.71 when the object distance is 0.3 m, the effective focal length FII is 37.51 when the object distance is infinite, the aperture FNO is 3.0, and the optical distortion is 0.37% to 0.11% when the object distance changes from 0.3 m to infinity.

[0136] Combination Figures 1 to 3As shown in Tables 1 to 3 above, the first embodiment is an imaging lens having at least one of the following characteristics: wide object distance (clear focus can be achieved from 0.3 m to infinity object distance), low distortion (absolute value of optical distortion ≤ 0.75%), high illumination (relative illumination RI ≥ 70%), miniaturization (total optical length TTL ≤ 79 mm), constant aperture (FNO = 3.0), no out-of-focus at high and low temperatures, and no lens thermalization.

[0137] Embodiment 2

[0138] Figure 4 Schematic diagram of the structure of an imaging lens according to Embodiment 2 of the present invention;

[0139] Figure 5 Schematic diagram of distortion of the imaging lens of Example 2 of the present invention when the object distance is 0.3m;

[0140] Figure 6 FIG. 4 is a schematic diagram of distortion of the imaging lens of Embodiment 2 of the present invention when the object distance is infinite.

[0141] In the second embodiment, the first lens L1 is a convex-convex lens with positive focal power, the second lens L2 is a concave-concave lens with negative focal power, the third lens L3 is a convex-convex lens with positive focal power, the fourth lens L4 is a concave-convex lens with negative focal power, the fifth lens L5 is a convex-convex lens with positive focal power, the sixth lens L6 is a concave-concave lens with negative focal power, the seventh lens L7 is a convex-convex lens with positive focal power, the eighth lens L8 is a concave-concave lens with negative focal power, and the ninth lens L9 is a convex-concave lens with positive focal power.

[0142] The third lens L3 and the fourth lens L4, the fifth lens L5 and the sixth lens L6 form a doublet lens, the seventh lens L7, the eighth lens L8 and the ninth lens L9 form a triplet lens, and the aperture stop STO is arranged behind the object side surface of the ninth lens L9.

[0143] The first lens L1 to the ninth lens L9 are all made of glass lens material.

[0144] Table 4 lists the relevant parameters of each lens in the imaging lens of this embodiment, including: surface type, curvature radius R, thickness d, refractive index Nd and Abbe number Vd of the material.

[0145]

[0146]

[0147] Table 4

[0148] Table 5 lists the variable spacing values ​​between the lens groups of the imaging lens of this embodiment when the object distance changes from 0.3M to infinity.

[0149] Surface number thickness When the object distance is 0.3M Object distance is infinite S7 T0 21.982 4.002 S10 T1 4.018 21.999

[0150] Table 5

[0151] In the second embodiment, the effective focal length FI of the imaging lens is 40.44 when the object distance is 0.3m, the effective focal length FII is 38.08 when the object distance is infinity, the aperture FNO is 3.0, and the optical distortion is -0.24% to -0.63% when the object distance changes from 0.3m to infinity.

[0152] Combination Figures 4 to 6 As shown in Tables 1, 4 and 5 above, the second embodiment is an imaging lens having at least one of the following characteristics: wide object distance (clear focus can be achieved from 0.3 m to infinity object distance), low distortion (absolute value of optical distortion ≤ 0.75%), high illumination (relative illumination RI ≥ 70%), miniaturization (total optical length TTL ≤ 79 mm), constant aperture (FNO = 3.0), no out-of-focus at high and low temperatures, and no lens thermalization.

[0153] Embodiment 3

[0154] Figure 7 Schematic diagram of the structure of an imaging lens according to Embodiment 3 of the present invention;

[0155] Figure 8 Schematic diagram of distortion of the imaging lens of Example 3 of the present invention when the object distance is 0.3m;

[0156] Fig. 9 FIG. 4 is a schematic diagram of distortion of the imaging lens of Embodiment 3 of the present invention when the object distance is infinite.

[0157] In embodiment 3, the first lens L1 is a convex-planar lens with positive optical power, the second lens L2 is a concave-concave lens with negative optical power, the third lens L3 is a convex-convex lens with positive optical power, the fourth lens L4 is a concave-convex lens with negative optical power, the fifth lens L5 is a concave-convex lens with positive optical power, the sixth lens L6 is a concave-concave lens with negative optical power, the seventh lens L7 is a convex-convex lens with positive optical power, the eighth lens L8 is a concave-concave lens with negative optical power, and the ninth lens L9 is a convex-concave lens with positive optical power.

[0158] The third lens L3 and the fourth lens L4, the fifth lens L5 and the sixth lens L6, the eighth lens L8 and the ninth lens L9 respectively form a doublet lens. A stop STO is disposed behind the object side surface of the ninth lens L9.

[0159] The first lens L1 to the ninth lens L9 are all made of glass lens material.

[0160] Table 6 lists the relevant parameters of each lens in the imaging lens of this embodiment, including: surface type, curvature radius R, thickness d, refractive index Nd and Abbe number Vd of the material.

[0161] Surface serial number Surface type Curvature radius R Thickness d Refractive index Nd Abbe number Vd S1 Spherical 36.212 2.330 1.871 40.73 S2 Spherical Infinity 1.090 S3 Spherical -47.519 0.700 1.620 36.35 S4 Spherical 28.754 11.440 S5 Spherical 56.035 3.790 1.593 66.99 S6 Spherical -20.690 0.700 1.581 40.92 S7 Spherical -42.181 T0 S8 Spherical -145.915 1.830 1.946 17.99 S9 Spherical -46.714 0.700 1.581 40.92 S10 Spherical 29.787 T1 S11 Spherical 21.017 2.530 2.001 29.13 S12 Spherical -100.000 1.130 S13 Spherical -65.762 0.700 1.741 27.76 S14 Spherical 9.304 2.780 1.593 68.35 S15 Spherical 90.129 0.320 S16(STO) Spherical Infinity 27.060 S17 Spherical Infinity 0.900 1.517 64.21 S18 Spherical Infinity 0.040 S19(IMA) Spherical Infinity -

[0162] Table 6

[0163] Table 7 lists the variable spacing values ​​between the lens groups of the imaging lens of this embodiment when the object distance changes from 0.3M to infinity.

[0164] Surface number thickness Wide-angle end Telephoto end S7 T0 16.963 4.168 S10 T1 3.998 16.793

[0165] Table 7

[0166] In the third embodiment, the effective focal length FI of the imaging lens is 41.09 when the object distance is 0.3 m, the effective focal length FII is 37.53 when the object distance is infinity, the aperture FNO is 3.0, and the optical distortion is -0.22% to -0.72% when the object distance changes from 0.3 m to infinity.

[0167] Combination Figures 7 to 9 As shown in Tables 1, 6 and 7 above, the third embodiment is an imaging lens having at least one of the following characteristics: wide object distance (clear focus can be achieved from 0.3 m to infinity), low distortion (absolute value of optical distortion ≤ 0.75%), high illumination (relative illumination RI ≥ 70%), miniaturization (total optical length TTL ≤ 79 mm), constant aperture (FNO = 3.0), no out-of-focus at high and low temperatures, and no lens thermalization.

[0168] Embodiment 4

[0169] Fig.10 Schematic diagram of the structure of an imaging lens according to Embodiment 4 of the present invention;

[0170] Fig.11 Schematic diagram of distortion of the imaging lens of Example 4 of the present invention when the object distance is 0.3 m;

[0171] Fig.12 FIG. 4 is a schematic diagram of distortion of the imaging lens of Embodiment 4 of the present invention when the object distance is infinite.

[0172] In embodiment 4, the first lens L1 is a convex-concave lens with positive focal power, the second lens L2 is a concave-concave lens with negative focal power, the third lens L3 is a convex-convex lens with positive focal power, the fourth lens L4 is a concave-concave lens with negative focal power, the fifth lens L5 is a concave-convex lens with positive focal power, the sixth lens L6 is a concave-concave lens with negative focal power, the seventh lens L7 is a concave-concave lens with negative focal power, the eighth lens L8 is a convex-convex lens with positive focal power, and the ninth lens L9 is a convex-convex lens with positive focal power.

[0173] The third lens L3 and the fourth lens L4, the fifth lens L5 and the sixth lens L6, the seventh lens L7 and the eighth lens L8 form a doublet lens. A stop STO is disposed behind the object side surface of the ninth lens L9.

[0174] The first lens L1 to the ninth lens L9 are all made of glass lens material.

[0175] Table 8 lists the relevant parameters of each lens in the imaging lens of this embodiment, including: surface type, curvature radius R, thickness d, refractive index Nd and Abbe number Vd of the material.

[0176]

[0177]

[0178] Table 8

[0179] Table 9 lists the variable spacing values ​​between the lens groups of the imaging lens of this embodiment when the object distance changes from 0.3M to infinity.

[0180] Surface number thickness Wide-angle end Telephoto end S7 T0 17.000 4.207 S10 T1 8.262 21.056

[0181] Table 9

[0182] In the fourth embodiment, the effective focal length FI of the imaging lens is 45.78 when the object distance is 0.3 m, the effective focal length FII is 38.10 when the object distance is infinity, the aperture FNO is 3.0, and the optical distortion is 0.03% to -0.35% when the object distance changes from 0.3 m to infinity.

[0183] Combination Figures 10 to 12 As shown in Table 1, Table 8 and Table 9, the fourth embodiment is an imaging lens having at least one of the following characteristics: wide object distance (clear focus can be achieved from 0.3 m to infinity), low distortion (absolute value of optical distortion ≤ 0.75%), high illumination (relative illumination RI ≥ 70%), miniaturization (total optical length TTL ≤ 79 mm), constant aperture (FNO = 3.0), no out-of-focus at high and low temperatures, and no lens thermalization.

[0184] Embodiment 5

[0185] Fig.13 Schematic diagram of the structure of an imaging lens according to Embodiment 5 of the present invention;

[0186] Fig.14 Schematic diagram of distortion of the imaging lens of Example 5 of the present invention when the object distance is 0.3 m;

[0187] Fig.15 FIG. 4 is a schematic diagram of distortion of the imaging lens of Embodiment 5 of the present invention when the object distance is infinite.

[0188] In embodiment five, the first lens L1 is a convex-planar lens with positive optical power, the second lens L2 is a concave-concave lens with negative optical power, the third lens L3 is a convex-convex lens with positive optical power, the fourth lens L4 is a concave-convex lens with negative optical power, the fifth lens L5 is a concave-convex lens with positive optical power, the sixth lens L6 is a concave-concave lens with negative optical power, the seventh lens L7 is a convex-convex lens with positive optical power, the eighth lens L8 is a concave-concave lens with negative optical power, and the ninth lens L9 is a convex-concave lens with positive optical power.

[0189] The third lens L3 and the fourth lens L4, the fifth lens L5 and the sixth lens L6 form a doublet lens, the seventh lens L7, the eighth lens L8 and the ninth lens L9 form a triplet lens, and the aperture stop STO is arranged behind the object side surface of the ninth lens L9.

[0190] The first lens L1 to the ninth lens L9 are all made of glass lens material.

[0191] Table 10 lists the relevant parameters of each lens in the imaging lens of this embodiment, including: surface type, curvature radius R, thickness d, refractive index Nd and Abbe number Vd of the material.

[0192] Surface serial number Surface type Curvature radius R Thickness d Refractive index Nd Abbe number Vd S1 Spherical 30.883 2.480 1.835 42.73 S2 Spherical Infinity 4.120 S3 Spherical -45.701 0.800 1.620 36.35 S4 Spherical 19.242 9.580 S5 Spherical 41.868 4.320 1.593 66.99 S6 Spherical -15.141 0.700 1.517 52.19 S7 Spherical -44.44 T0 S8 Spherical -120.516 1.730 1.946 17.99 S9 Spherical -46.567 0.700 1.581 40.92 S10 Spherical 28.004 T1 S11 Spherical 23.408 2.380 2.001 29.13 S12 Spherical -61.846 0.700 1.699 30.05 S13 Spherical 9.046 2.830 1.593 66.99 S14 Spherical 95.514 0.620 S15(STO) Spherical Infinity 26.750 S16 Spherical Infinity 0.900 1.517 64.21 S17 Spherical Infinity 0.040 S18(IMA) Spherical Infinity 0

[0193] Table 10

[0194] Table 11 lists the variable spacing values ​​between the lens groups of the imaging lens of this embodiment when the object distance changes from 0.3M to infinity.

[0195] Surface number thickness Wide-angle end Telephoto end S7 T0 16.354 4.150 S10 T1 3.998 16.202

[0196] Table 11

[0197] In the fifth embodiment, the effective focal length FI of the imaging lens is 41.90 when the object distance is 0.3 m, the effective focal length FII is 37.52 when the object distance is infinity, the aperture FNO is 3.0, and the optical distortion is -0.18% to -0.61% when the object distance changes from 0.3 m to infinity.

[0198] Combination Figures 13 to 15 As shown in Table 1, Table 10 and Table 11, the fifth embodiment is an imaging lens having at least one of the following characteristics: wide object distance (clear focus can be achieved from 0.3 m to infinity object distance), low distortion (absolute value of optical distortion ≤ 0.75%), high illumination (relative illumination RI ≥ 70%), miniaturization (total optical length TTL ≤ 79 mm), constant aperture (FNO = 3.0), no out-of-focus at high and low temperatures, and no lens thermalization.

[0199] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other.

Claims

1. An imaging lens, characterized in that: The lens comprises, in order from the object side to the image side of the optical axis: a first lens group (G1) with positive focal power, a second lens group (G2) with negative focal power, and a third lens group (G3) with positive focal power, wherein the first lens group (G1) and the third lens group are fixed lens groups, and the second lens group (G2) is a focus adjustment group that moves along the optical axis of the imaging lens; The first lens group (G1) comprises in sequence: a first lens (L1) with positive optical power, a second lens (L2) with negative optical power, a third lens (L3) with positive optical power and a fourth lens (L4) with negative optical power, a total of four lenses; The second lens group (G2) includes in sequence: a fifth lens (L5) with positive optical power and a sixth lens (L6) with negative optical power, a total of two lenses; The third lens group (G3) comprises, in sequence: a seventh lens (L7), an eighth lens (L8) and a ninth lens (L9) with positive optical power, a total of three lenses; the optical power of the seventh lens (L7) and the eighth lens (L8) are opposite.

2. The imaging lens according to claim 1, characterized in that: The object side surface of the first lens (L1) is a convex surface, the image side surface of the second lens (L2) is a concave surface, the third lens (L3) is a convex-convex lens; and the object side surface of the fourth lens (L4) is a concave surface.

3. The imaging lens according to claim 1, wherein: The image side surface of the fifth lens (L5) is a convex surface; and the sixth lens (L6) is a concave-concave lens.

4. The imaging lens according to claim 1, wherein: The object side surface of the ninth lens (L9) is a convex surface.

5. The imaging lens according to claim 1, wherein: The third lens (L3) and the fourth lens (L4) form a doublet lens, and the fifth lens (L5) and the sixth lens (L6) form a doublet lens.

6. The imaging lens according to any one of claims 1 to 5, characterized in that: The effective focal length FG1 of the first lens group (G1) and the total effective focal length FI of the imaging lens when the object distance is 0.3 m satisfy the following relationship: 0.8≤FG1 / FI≤1.

7.

7. The imaging lens according to any one of claims 1 to 5, characterized in that: The effective focal length FG3 of the third lens group (G3) and the total effective focal length FI of the imaging lens when the object distance is 0.3 m satisfy the following relationship: 0.5≤FG3 / FI≤1.

1.

8. The imaging lens according to any one of claims 1 to 5, characterized in that: The focus moving distance d2 of the second lens group (G2) within the object distance variation range and the effective focal length FG2 of the second lens group (G2) satisfy the following relationship: -5.6≤FG2 / d2≤-3.

6.

9. The imaging lens according to any one of claims 1 to 5, characterized in that: An air spacing distance d23 between the second lens (L2) and the third lens (L3) on the optical axis and an effective focal length FG1 of the first lens group (G1) satisfy the following relationship: 2.5≤FG1 / d23≤120.

10. The imaging lens according to any one of claims 1 to 5, characterized in that: The combined effective focal length F34 of the third lens (L3) and the fourth lens (L4) and the effective focal length FG1 of the first lens group (G1) satisfy the following relationship: 0.2≤F34 / FG1≤1.1.

Images