CN114895435B

CN114895435B - Imaging system

Info

Publication number: CN114895435B
Application number: CN202210560823.4A
Authority: CN
Inventors: 闻人建科; 戴付建; 赵烈烽
Original assignee: Zhejiang Sunny Optics Co Ltd
Current assignee: Zhejiang Sunny Optics Co Ltd
Priority date: 2022-05-23
Filing date: 2022-05-23
Publication date: 2024-03-29
Anticipated expiration: 2042-05-23
Also published as: CN114895435A

Abstract

The application discloses an imaging system, which sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens with optical power from an object side to an image side along an optical axis, wherein the combined focal length of the first lens and the second lens has positive optical power, and the effective diameter part of the object side of the first lens is in a convex shape on the surface of the effective diameter part; the image side surface of at least three lenses of the first lens to the fifth lens is a concave surface; the fifth lens is a meniscus lens; the ninth lens is a biconvex lens or a biconcave lens; sigma (sigma) ⁴ _i＝1 |CT _i ‑CT _i+1 |/(CT _i +CT _i+1 ) < 1.5 and i is an integer from 1 to 4, wherein CT _i CT for the center thickness of the ith lens in the first to ninth lenses on the optical axis _i+1 Is the center thickness of the (i+1) th lens of the first to ninth lenses on the optical axis.

Description

Imaging system

Technical Field

The present application relates to the field of optical elements, and in particular to an imaging system.

Background

Along with the progress of science and the development of society, the functions of portable mobile terminals are increasing, wherein the shooting function has been one of the development directions of mobile terminals for at least twenty years, and the function realizes the functions of a plurality of cameras to a certain extent, reduces the shooting difficulty and cost, and provides convenience for daily shooting demands of people. Along with the increase of the requirements of diversified functions such as photographing, video recording, live broadcasting and the like of the mobile terminal, the requirements of users on the photographing quality of the mobile terminal are correspondingly improved.

In order to meet the requirements of the above diversified functions, the imaging lens mounted on the mobile terminal gradually develops multi-shooting structures such as double shooting, triple shooting and the like from a single shooting at the beginning, for example, an auxiliary lens such as a long focus, a micro-distance, a wide angle and the like can be assembled on the basis of the main imaging lens so as to be matched with the main imaging lens for use, thereby meeting the diversified shooting requirements such as long-range, micro-distance, wide angle and the like. However, the above auxiliary lens not only increases the overall weight and volume of the mobile terminal, but also presents challenges to the aesthetics, manufacturing costs and process of the terminal product. In addition, the imaging lens with the auxiliary lens is generally insufficient in telescopic shooting capability, and is easy to cause aberration problems such as distortion, astigmatism and chromatic aberration, and imaging quality is affected.

Therefore, there is a need for an auxiliary lens that can be combined with a conventional lens to make the whole imaging lens have smaller optical distortion while satisfying the telephoto characteristic, thereby realizing the telescopic photographing function.

It should be appreciated that this background section is intended to provide, in part, a useful background for understanding the technology, however, that such content does not necessarily fall within the knowledge or understanding of one of skill in the art prior to the filing date of this application.

Disclosure of Invention

An aspect of the present application provides an imaging system including, in order from an object side to an image side along an optical axis, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens having optical power, a combined focal length of the first lens and the second lens having positive optical power, wherein an effective diameter portion of an object side surface of the first lens has a convex shape on a surface thereof; the image side surfaces of at least three lenses from the first lens to the fifth lens are concave surfaces; the fifth lens is a meniscus lens; the ninth lens is a biconvex lens or a biconcave lens; the imaging system satisfies: sigma (sigma) ⁴ _i＝1 |CT _i -CT _i+1 |/(CT _i +CT _i+1 ) < 1.5 and i is an integer from 1 to 4, wherein CT _i CT for the center thickness of the ith lens from the first lens to the ninth lens on the optical axis _i+1 Is the center thickness of the i+1th lens of the first to ninth lenses on the optical axis.

In one embodiment of the present application, the imaging system further includes an imaging lens located at an image side of the ninth lens, the imaging system satisfying: and 40.0mm < TTL < 70.0mm, wherein TTL is the distance between the object side surface of the first lens and the imaging surface of the imaging lens on the optical axis.

In one embodiment of the present application, the imaging system further includes an imaging lens located on an image side of the ninth lens, the imaging lens including a plurality of lenses, the imaging system satisfying: 1.0 < TD/f < 4.0, wherein TD is the distance between the object side surface of the first lens and the image side surface of the ninth lens on the optical axis, and f is the total effective focal length of the lens groups formed by the first lens and the ninth lens.

In one embodiment of the present application, the imaging system satisfies: -40.0 < (f12+f67)/(f12-f 67) < 20.0, wherein f12 is the combined focal length of the first and second lenses and f67 is the combined focal length of the sixth and seventh lenses.

In one embodiment of the present application, the imaging system satisfies: 0 < T56/T89 < 2.5, wherein T56 is the air space of the fifth lens and the sixth lens on the optical axis, and T89 is the air space of the eighth lens and the ninth lens on the optical axis.

In one embodiment of the present application, the third lens has positive optical power, and the eighth lens has positive optical power, and the imaging system satisfies: 0 < f3/f8 < 3.0, wherein f3 is the effective focal length of the third lens, and f8 is the effective focal length of the eighth lens.

In one embodiment of the present application, the object side surface of the first lens is convex, and the imaging system satisfies: 2.0 < R4/R1 < 12.0, wherein R1 is the radius of curvature of the object side of the first lens and R4 is the radius of curvature of the image side of the second lens.

In one embodiment of the present application, the imaging system satisfies: 0 < R5/(R7+R8) < 5.0, wherein R5 is the radius of curvature of the object side surface of the third lens element, R7 is the radius of curvature of the object side surface of the fourth lens element, and R8 is the radius of curvature of the image side surface of the fourth lens element.

In one embodiment of the present application, the imaging system satisfies: -1.0 < (r14+r15)/(R14-R15) < 1.0, wherein R14 is the radius of curvature of the image side of the seventh lens and R15 is the radius of curvature of the object side of the eighth lens.

In one embodiment of the present application, the imaging system satisfies: R14/R15 > -2.5, wherein R14 is the radius of curvature of the image side of the seventh lens element and R15 is the radius of curvature of the object side of the eighth lens element.

In one embodiment of the present application, at least four lenses of the first lens to the ninth lens are spherical lenses made of glass.

In one embodiment of the present application, at least three lenses of the first lens to the fifth lens are spherical lenses made of glass.

In one embodiment of the present application, the imaging system satisfies: n7/(n8+n9) > 0.4, where N7 is the refractive index of the seventh lens, N8 is the refractive index of the eighth lens, and N9 is the refractive index of the ninth lens.

In one embodiment of the present application, the imaging system satisfies: v9/[ (V7+V8)/2 ] > 0.4, wherein V7 is the Abbe number of the seventh lens, N8 is the Abbe number of the eighth lens, and N9 is the Abbe number of the ninth lens.

In one embodiment of the present application, the imaging system satisfies: (n1+n2+n3+n4+n5)/5 > 1.5, wherein N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, N3 is the refractive index of the third lens, N4 is the refractive index of the fourth lens, and N5 is the refractive index of the fifth lens.

In one embodiment of the present application, the imaging system satisfies: 20.0 < (v1+v2+v3+v4+v5)/5 < 60.0, wherein V1 is the abbe number of the first lens, V2 is the abbe number of the second lens, V3 is the abbe number of the third lens, V4 is the abbe number of the fourth lens, and V5 is the abbe number of the fifth lens.

In one embodiment of the present application, at least two pairs of adjacent lenses in the imaging system are cemented lenses.

In one embodiment of the present application, the first lens and the second lens are cemented lenses, and the sixth lens and the seventh lens are cemented lenses.

In one embodiment of the present application, the second lens has negative optical power, and its image side surface is concave; and

the image side surface of the fourth lens is a concave surface.

In one embodiment of the present application, the object side surface of the third lens is a convex surface; the sixth lens has negative focal power; the seventh lens has positive focal power, and the image side surface of the seventh lens is a convex surface; the object side surface of the eighth lens is a convex surface.

In one embodiment of the present application, a radius of curvature of one of the image side surface of the fifth lens and the object side surface of the sixth lens is positive, and a radius of curvature of the other is negative.

In one embodiment of the present application, the imaging system satisfies: 0< (ct6+ct7)/(ct8+ct9) <2.0, wherein CT6 is the center thickness of the sixth lens on the optical axis, CT7 is the center thickness of the seventh lens on the optical axis, CT8 is the center thickness of the eighth lens on the optical axis, and CT9 is the center thickness of the ninth lens on the optical axis.

Another aspect of the present application also provides an electronic device comprising any one of the imaging systems described above. The electronic device provided by the application can be an image acquisition device, and the specific type of the image acquisition device is not limited, and for example, the electronic device can be a camera, a video camera, a monitoring camera or a camera module of various mobile terminals. Compared with the related art, the electronic equipment has better shooting quality due to the improvement of the technical problems.

The imaging system comprises a plurality of (e.g. nine) lenses, and the imaging system can have a long focal length characteristic by reasonably distributing the combined focal length of the first lens and the second lens, the shape of the object side surface of the first lens, the surface type of the image side of at least three lenses from the first lens to the fifth lens, the surface type of the ninth lens and the sum of the ratio of the difference between the central thicknesses of all adjacent lenses from the first lens to the fifth lens on the optical axis to the sum of the thicknesses of all adjacent lenses reasonably arranged, so that the imaging system can have the long focal length characteristic, the optical distortion of the imaging system can be reduced, the aberration problems such as astigmatism and chromatic aberration can be improved, and the imaging quality can be improved, and the imaging system can have a better long-looking function.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments, made with reference to the following drawings, in which:

FIG. 1 shows a schematic configuration of an imaging system according to embodiment 1 of the present application;

fig. 2 shows a schematic configuration diagram of a lens group included in an imaging system according to embodiment 1 of the present application;

fig. 3A to 3C show an astigmatism curve, a distortion curve, and an on-axis chromatic aberration curve, respectively, of the imaging system according to embodiment 1 of the present application;

fig. 4 shows a schematic structural diagram of an imaging system according to embodiment 2 of the present application;

fig. 5A to 5C show an astigmatism curve, a distortion curve, and an on-axis chromatic aberration curve, respectively, of the imaging system according to embodiment 2 of the present application;

fig. 6 shows a schematic structural diagram of an imaging system according to embodiment 3 of the present application;

fig. 7A to 7C show an astigmatism curve, a distortion curve, and an on-axis chromatic aberration curve, respectively, of the imaging system according to embodiment 3 of the present application;

fig. 8 shows a schematic structural diagram of an imaging system according to embodiment 4 of the present application;

fig. 9A to 9C show an astigmatism curve, a distortion curve, and an on-axis chromatic aberration curve, respectively, of the imaging system according to embodiment 4 of the present application;

Fig. 10 shows a schematic structural diagram of an imaging system according to embodiment 5 of the present application;

fig. 11A to 11C show an astigmatism curve, a distortion curve, and an on-axis chromatic aberration curve, respectively, of the imaging system according to embodiment 5 of the present application;

fig. 12 shows a schematic configuration diagram of an imaging system according to embodiment 6 of the present application;

fig. 13A to 13C show an astigmatism curve, a distortion curve, and an on-axis chromatic aberration curve, respectively, of the imaging system according to embodiment 6 of the present application;

fig. 14 shows a schematic structural view of an imaging system according to embodiment 7 of the present application;

fig. 15A to 15C show an astigmatism curve, a distortion curve, and an on-axis chromatic aberration curve, respectively, of the imaging system according to embodiment 7 of the present application;

fig. 16 shows a schematic structural view of an imaging system according to embodiment 8 of the present application;

fig. 17A to 17C show an astigmatism curve, a distortion curve, and an on-axis chromatic aberration curve, respectively, of the imaging system according to embodiment 8 of the present application.

Detailed Description

For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed description are merely illustrative of exemplary embodiments of the application and are not intended to limit the scope of the application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.

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

In the drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for convenience of explanation. Specifically, the spherical or aspherical shape shown in the drawings is shown by way of example. That is, the shape of the spherical or aspherical surface is not limited to the shape of the spherical or aspherical surface shown in the drawings. The figures are merely examples and are not drawn to scale.

Herein, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position is not defined, then the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region. The determination of the surface shape in the paraxial region may be performed according to a method common in the art, for example, by determining the roughness in positive and negative of an R value (R means a radius of curvature of the paraxial region). Herein, the surface of each lens closest to the subject is referred to as the object side of the lens, and the surface of each lens closest to the imaging plane is referred to as the image side of the lens. In the object side surface, when the R value is positive, the object side surface is judged to be convex, and when the R value is negative, the object side surface is judged to be concave; in the image side, the concave surface is determined when the R value is positive, and the convex surface is determined when the R value is negative.

It will be further understood that the terms "comprises," "comprising," "includes," "including," "having," "containing," and/or "containing," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Furthermore, when an expression such as "at least one of …" occurs after a list of features listed, the entire listed feature is modified rather than a separate element in the list. Furthermore, when describing embodiments of the present application, the use of "may" refer to "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

The features, principles, and other aspects of the present application are described in detail below.

The imaging system according to the exemplary embodiment of the present application may include a lens group and an imaging lens disposed in order from an object side to an image side along an optical axis, wherein the lens group and the imaging system each include a plurality of lenses, optionally, the lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens having optical powers, respectively, in order from the object side to the image side along the optical axis, and the imaging lens is located at the image side of the ninth lens.

In an exemplary embodiment, the imaging lens may be, for example, a tele lens, so that the imaging system may have a tele characteristic, and may implement a better tele function. In some cases, the number of lenses included in the imaging lens may be set arbitrarily according to actual needs, or may be set in an ultra-thin manner on the premise of comprehensively considering the number of lenses of the lens group and enabling the imaging system to have a miniaturized feature. In an exemplary embodiment, the first lens may have positive or negative optical power, the object-side surface thereof may be convex, and the image-side surface thereof may be convex or concave; alternatively, the effective diameter portion of the object side surface of the first lens is in a convex shape on its surface, and the effective diameter portion (which may also be referred to as "effective diameter portion" or "effective optical area portion") is a portion that plays an optical role in the lens. The second lens element with negative or positive refractive power may have a convex or concave object-side surface and a concave image-side surface; the third lens element may have positive refractive power, wherein an object-side surface thereof may be convex, and an image-side surface thereof may be convex or concave; the fourth lens element may have positive refractive power, wherein an object-side surface thereof may be convex and an image-side surface thereof may be concave; the fifth lens element may have negative optical power, and the radii of curvature of the object-side surface and the image-side surface thereof may be both positive or both negative, i.e., the fifth lens element is meniscus-shaped; the sixth lens element with negative or positive refractive power may have a convex object-side surface or a concave image-side surface; the seventh lens element with positive or negative refractive power may have a convex object-side surface or a concave image-side surface; the eighth lens element may have positive refractive power, the object-side surface thereof may be convex, the image-side surface thereof may be convex or concave, the ninth lens element may have positive or negative refractive power, one of the object-side surface and the image-side surface thereof may have a positive radius of curvature, and the other one may have a negative radius of curvature, e.g., the object-side surface and the image-side surface of the ninth lens element may be both convex or both concave. The imaging effect can be effectively improved by reasonably distributing the surface shape and the focal power of each lens of the imaging system. In addition, the surface type of each lens is reasonably controlled, so that the imaging system can be effectively improved in resolution and the aberration of the imaging system can be balanced by adjusting the path of light rays in the optical system.

In an exemplary embodiment, the image-side surface of the second lens is concave; and the image side surface of the fourth lens is a concave surface. The concave image sides of the second lens and the fourth lens are controlled, so that the sizes of the second lens and the fourth lens can be effectively reduced by controlling the shapes of the two lenses, the overall size and weight of the imaging system can be effectively reduced, and the application scene of the imaging system is enlarged.

In an exemplary embodiment, the object side surface of the third lens is convex; the image side surface of the seventh lens is a convex surface; the object side surface of the eighth lens is a convex surface. The object side of the third lens is controlled to be the convex surface, the image side of the seventh lens is controlled to be the convex surface, and the object side of the eighth lens is controlled to be the convex surface, so that the size of the lenses can be effectively reduced by controlling the shapes of the lenses, the overall size and weight of the imaging system can be effectively reduced, and the application scene of the imaging system can be increased.

In an exemplary embodiment, one of the image side surface of the fifth lens and the object side surface of the sixth lens has a positive radius of curvature, and the other has a negative radius of curvature. The system can be ensured to be in a certain aperture range by controlling the conditions, the size of luminous flux entering the system is improved, the lens group is used as an auxiliary lens to have higher resolving power, and the imaging effect of the imaging lens as a main imaging lens is not influenced.

In an exemplary embodiment, the imaging system satisfies: sigma (sigma) ⁴ _i＝1 |CT _i -CT _i+1 |/(CT _i +CT _i+1 ) < 1.5 and i is an integer from 1 to 4, wherein CT _i CT for the center thickness of the ith lens in the first to ninth lenses on the optical axis _i+1 Is the center thickness of the i+1th lens of the first to ninth lenses on the optical axis. Further, 0.7 < Σ ⁴ _i＝1 |CT _i -CT _i+1 |/(CT _i +CT _i+1 ) < 1.4. Through reasonable thickness setting of the first lens, the second lens, the third lens, the fourth lens and the fifth lens, the imaging system has the characteristics of long focal length, small optical distortion and miniaturization. In addition, meeting the above conditions is beneficial to realizing the butt joint combination of the lens group (for example, the auxiliary lens) and the imaging lens (for example, the main imaging lens), ensuring that the lens group is used as the auxiliary lens without influencing the imaging effect of the main imaging lens, improving the magnification of the main imaging lens and realizing the telescopic function. And moreover, the thickness of each lens in the first lens to the fifth lens can be increased by meeting the conditions, the caliber of the lens is increased to control the rationality of the thickness design of the first lens to the fifth lens, so that the good formability of the lenses and the assembly stability of the front five lenses can be further ensured, and the lens group serving as an auxiliary lens can meet the convergence performance requirement of front light rays of the main shooting lens passing through the front five lenses.

In an exemplary embodiment, the imaging system further comprises an imaging lens located at an image side of the lens group, the imaging system satisfying: 40.0mm < TTL < 70.0mm, wherein TTL is the distance from the object side surface of the first lens to the imaging surface on the optical axis. Further, 50.0mm < TTL < 69.0mm. By controlling the length of the imaging system, the imaging system has the characteristics of miniaturization and ultra-thinning on the premise of ensuring the imaging effect.

In an exemplary embodiment, the first to ninth lenses constitute a lens group, the imaging system further includes an imaging lens located on an image side of the lens group, the imaging lens includes a plurality of lenses, the imaging system satisfies: 1.0 < TD/f < 4.0, wherein TD is the distance between the object side surface of the first lens element and the image side surface of the ninth lens element on the optical axis, and f is the total effective focal length of the lens assembly. Through the total effective focal length of the lens group which is reasonably arranged, when the lens group is combined with an imaging lens, the combined focal length of an imaging system can be effectively improved, and therefore the shooting capability of the imaging system is improved. In addition, the length of the imaging system can be reduced by reasonably controlling the total effective focal length of the imaging system and the distance between the object side surface of the first lens and the image side surface of the ninth lens on the optical axis, so that the imaging system has the characteristic of miniaturization.

In an exemplary embodiment, the imaging system satisfies: -40.0 < (f12+f67)/(f12-f 67) < 20.0, wherein f12 is the combined focal length of the first lens and the second lens and f67 is the combined focal length of the sixth lens and the seventh lens. By controlling the focal length relation between the first lens and the second lens and between the sixth lens and the seventh lens, the focal power of the system can be reasonably distributed, the trend of light passing through the first lens and the second lens and the trend of light passing through the sixth lens and the seventh lens can be controlled, the aberration generated by other lenses can be balanced, the light converging position can be adjusted, the spherical aberration, the coma, the astigmatism, the curvature of field, the distortion, the chromatic aberration and other aberration of the system can be corrected, and the imaging quality of the whole system can be improved.

In an exemplary embodiment, the imaging system satisfies: 0 < T56/T89 < 2.5, wherein T56 is the air space of the fifth lens and the sixth lens on the optical axis, and T89 is the air space of the eighth lens and the ninth lens on the optical axis. By reasonably setting the distance between the fifth lens and the sixth lens and the distance between the eighth lens and the ninth lens, the focal power of the fifth lens, the sixth lens, the eighth lens and the ninth lens can be improved, the sensitivity of the lenses can be reduced, and the processability of the lenses can be improved.

In an exemplary embodiment, the third lens has positive optical power, and the eighth lens has positive optical power, and the imaging system satisfies: 0 < f3/f8 < 3.0, wherein f3 is the effective focal length of the third lens and f8 is the effective focal length of the eighth lens. By reasonably distributing the relation between the focal lengths of the third lens and the eighth lens, the focal power can be reasonably distributed, the ratio of the aberration generated by the third lens in the comprehensive aberration distribution can be minimized, the sensitivity of the third lens is reduced, and meanwhile, the imaging system is ensured to have smaller optical distortion.

In an exemplary embodiment, the object side surface of the first lens is convex, and the imaging system satisfies: 2.0 < R4/R1 < 12.0, wherein R1 is the radius of curvature of the object side of the first lens element and R4 is the radius of curvature of the image side of the second lens element. The control of the surface shape of the first lens is beneficial to realizing the butt joint combination of the lens group and the imaging lens, and the magnification of the original lens is improved, so that the telescopic function is realized; in addition, by controlling the curvature radius relation of the first lens and the second lens, the focal power of the first lens can be improved, the sensitivity of the first lens can be reduced, and the processability of the lens can be improved.

In an exemplary embodiment, the imaging system satisfies: 0 < R5/(R7+R8) < 5.0, wherein R5 is the radius of curvature of the object side of the third lens element, R7 is the radius of curvature of the object side of the fourth lens element, and R8 is the radius of curvature of the image side of the fourth lens element. Further, the imaging system satisfies: R5/(R7+R8) < 3.5, and by reasonably controlling the curvature radius of the object side surface of the third lens and the image side surface of the fourth lens, the distribution of the focal power of the third lens and the fourth lens in the imaging system can be controlled by controlling the shapes of the third lens and the fourth lens, so that the influence of the optical performance of the field Qu Duiguang can be effectively reduced, and the imaging quality of the imaging system is improved.

In an exemplary embodiment, the imaging system satisfies: R14/R15 > -2.5, wherein R14 is the radius of curvature of the image side of the seventh lens element and R15 is the radius of curvature of the object side of the eighth lens element. Through reasonably controlling the relation between the curvature radiuses of the image side surface of the seventh lens and the object side surface of the eighth lens, the ghost image intensity between the two lenses can be reduced by controlling the shapes of the seventh lens and the eighth lens, so that the aberration can be effectively balanced, the use of the imaging lens as a main shooting lens is not influenced when the lens group is used as an auxiliary lens, and the imaging quality of an imaging system is improved.

In an exemplary embodiment, the imaging system satisfies: -1.0 < (r14+r15)/(R14-R15) < 1.0, wherein R14 is the radius of curvature of the image side of the seventh lens and R15 is the radius of curvature of the object side of the eighth lens. Further, the imaging system satisfies: -0.5 < (R14+R15)/(R14-R15) < 0,0 < (R14+R15)/(R14-R15) < 0.5. By further reasonably controlling the relation between the curvature radiuses of the image side surface of the seventh lens and the object side surface of the eighth lens, the ghost image intensity between the two lenses can be reduced by controlling the shapes of the seventh lens and the eighth lens, so that the aberration can be effectively balanced, the use of the imaging lens as a main shooting lens is not influenced when the lens group is used as an auxiliary lens, and the imaging quality of the imaging system is improved.

In an exemplary embodiment, the imaging system satisfies: n7/(n8+n9) > 0.4, where N7 is the refractive index of the seventh lens, N8 is the refractive index of the eighth lens, and N9 is the refractive index of the ninth lens. Further, the imaging system satisfies: N7/(N8+N9) < 0.7, and the above conditions are controlled to be within a reasonable range, so that the long focal effect of the lens group is realized, the overall focal power of the imaging system can be reasonably distributed, and the imaging quality is improved.

In an exemplary embodiment, the imaging system satisfies: v9/[ (V7+V8)/2 ] > 0.4, wherein V7 is the Abbe number of the seventh lens, N8 is the Abbe number of the eighth lens, and N9 is the Abbe number of the ninth lens. Further, the imaging system satisfies: v9/[ (V7 + V8)/2 ] < 2.5, the above conditions are controlled to be within a reasonable range, so that reasonable use of glass materials is controlled, aberration can be effectively balanced, and imaging quality of a lens is improved.

In an exemplary embodiment, the imaging system satisfies: (n1+n2+n3+n4+n5)/5 > 1.5, wherein N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, N3 is the refractive index of the third lens, N4 is the refractive index of the fourth lens, and N5 is the refractive index of the fifth lens. By controlling the average value of the refractive indexes of the lenses from the first lens to the fifth lens, the lenses from the first lens to the fifth lens can adapt to high-refractive-index materials, so that the volume and the size of an imaging lens can be effectively reduced on the premise of realizing a large focal length, and portability is improved.

In an exemplary embodiment, the imaging system satisfies: 20.0 < (v1+v2+v3+v4+v5)/5 < 60.0, wherein V1 is the abbe number of the first lens, V2 is the abbe number of the second lens, V3 is the abbe number of the third lens, V4 is the abbe number of the fourth lens, and V5 is the abbe number of the fifth lens. The average value of the dispersion coefficients of the lenses in the first lens to the fifth lens is controlled, so that the focal power of each lens can be reasonably distributed, the focal length of the imaging system is effectively improved, the telescopic function of the imaging system is realized, and the use scene of the imaging system is improved.

In an exemplary embodiment, the imaging system satisfies: 0 < (CT6+CT7)/(CT8+CT9) < 2.0, wherein CT6 is the center thickness of the sixth lens on the optical axis, CT7 is the center thickness of the seventh lens on the optical axis, CT8 is the center thickness of the eighth lens on the optical axis, and CT9 is the center thickness of the ninth lens on the optical axis. By reasonably setting the relation among the thicknesses of the sixth lens, the seventh lens, the eighth lens and the ninth lens, the lens manufacturing process is improved, and the system can be manufactured and produced.

In an exemplary embodiment, at least two pairs of adjacent lenses in the imaging system are cemented lenses. Through reasonable setting of the cemented lens, the vertical axis chromatic aberration of the system can be effectively reduced.

In an exemplary embodiment, the first lens and the second lens are cemented lenses, and the sixth lens and the seventh lens are cemented lenses. By arranging the first lens and the second lens as the cemented lens and the sixth lens and the seventh lens as the cemented lens, the vertical axis chromatic aberration of the system can be effectively reduced.

In an exemplary embodiment, the imaging system according to the present application may further include a filter for correcting color deviation and/or a protective glass for protecting the photosensitive element located on the imaging surface.

In an exemplary embodiment, the imaging system according to the present application includes at least four lenses of the first lens to the ninth lens that are spherical lenses made of glass, optionally, at least three lenses of the first lens to the fifth lens may be spherical lenses made of glass, so as to ensure low cost requirements of the lens group (for example, as an externally hung auxiliary lens) as much as possible on the premise of meeting imaging quality, and reduce mold opening cost of the plastic lens.

In an exemplary embodiment, at least one of the mirrors of each of the first to ninth lenses is an aspherical mirror. The aspherical lens is characterized in that: the curvature varies continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has a better radius of curvature characteristic, and has advantages of improving distortion aberration and improving astigmatic aberration. By adopting the aspherical lens, aberration occurring during imaging can be eliminated as much as possible, thereby improving imaging quality. However, those skilled in the art will appreciate that the various results and advantages described in this specification can be obtained by varying the number of lenses making up a lens group or imaging system without departing from the technical solution claimed herein. For example, although the description has been made by taking the example in which the lens group includes nine lenses in the embodiment, the lens group is not limited to including nine lenses. The lens group may also include other numbers of lenses, if desired.

Specific examples of imaging systems applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

Example 1

An imaging system according to embodiment 1 of the present application is described below with reference to fig. 1 to 3C. As shown in fig. 1, the imaging system includes a lens assembly 10, a stop STO and an imaging lens 20 sequentially disposed from an object side to an image side along an optical axis, wherein the lens assembly 10 sequentially includes, from the object side to the image side along the optical axis: the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the fifth lens E5, the sixth lens E6, the seventh lens E7, the eighth lens E8, and the ninth lens E9. The imaging system further includes an imaging plane disposed on the image side of the imaging lens 20. Fig. 2 shows a schematic structural diagram of the lens group 10.

The first lens element E1 has positive refractive power, wherein an object-side surface S1 thereof is convex, and an image-side surface S2 thereof is convex. The second lens element E2 has negative refractive power, wherein an object-side surface S2 thereof is concave, and an image-side surface S3 thereof is concave. The third lens element E3 has positive refractive power, wherein an object-side surface S4 thereof is convex, and an image-side surface S5 thereof is convex. The fourth lens element E4 has positive refractive power, wherein an object-side surface S6 thereof is convex, and an image-side surface S7 thereof is concave. The fifth lens element E5 has negative refractive power, wherein an object-side surface S8 thereof is convex, an image-side surface S9 thereof is concave, the sixth lens element E6 has negative refractive power, an object-side surface S10 thereof is concave, an image-side surface S11 thereof is concave, the seventh lens element has positive refractive power, an object-side surface S11 thereof is convex, an image-side surface S12 thereof is convex, the eighth lens element has positive refractive power, an object-side surface S13 thereof is convex, an image-side surface S14 thereof is convex, a ninth lens element has positive refractive power, an object-side surface S15 thereof is convex, and an image-side surface S16 thereof is convex. Light from the object sequentially passes through the respective surfaces S1 to S16 of the lens group 10 and the respective surfaces of the lenses of the imaging lens 20, and is finally imaged on the imaging surface S17.

The first lens element E1 to the fourth lens element E4, the sixth lens element E6, the seventh lens element E7 and the ninth lens element E9 are made of glass.

Table 1 shows the basic parameter table of the lens group of example 1, in which the unit of radius of curvature, thickness/distance, and focal length are all millimeters (mm).

TABLE 1

In this embodiment, the total effective focal length f of the imaging system is 23.99mm, the distance TTL between the object side surface S1 of the first lens E1 and the imaging surface S17 on the optical axis is 55.31mm, the half of the diagonal length ImgH of the effective pixel area on the imaging surface S17 is 3.58mm, and the maximum half field angle Semi-FOV of the imaging system is 10.08 °.

In the present embodiment, the fifth lens E5 and the eighth lens E8 may be aspherical lenses. The aspherical surface profile x may be defined using, but not limited to, the following aspherical formula:

wherein x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at the position with the height h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c=1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 1 above); k is a conic coefficient; ai is the correction coefficient of the aspherical i-th order. The following table 2 gives the higher order coefficients A4, A6, A8, a10 and a12 that can be used for each of the aspherical mirrors S8, S9, S13 and S14 in example 1.

Face number	A4	A6	A8	A10	A12
						S8	-7.2551E-01	-8.5136E-02	-1.3802E-02	-3.3972E-03	-5.5092E-04
S9	-3.1426E-01	-4.4067E-02	-5.8739E-03	-7.1204E-04	-7.4045E-05
						S13	-1.0552E-01	-1.3897E-02	-6.7256E-03	-3.8283E-03	-8.0023E-04
S14	4.4033E-01	4.9146E-03	-4.9874E-03	-3.3352E-03	-6.8357E-04

TABLE 2

Fig. 3A shows an astigmatism curve of the imaging system of embodiment 1, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 3B shows a distortion curve of the imaging system of embodiment 1, which represents distortion magnitude values corresponding to different image heights. Fig. 3C shows an on-axis chromatic aberration curve of the imaging system of embodiment 1, which represents the focus offset of light rays of different wavelengths after passing through the imaging system. As can be seen from fig. 3A to 3C, the imaging system of embodiment 1 can achieve good imaging quality.

Example 2

An imaging system according to embodiment 2 of the present application is described below with reference to fig. 4 to 5C. As shown in fig. 5, the imaging system includes a lens group 10, a stop STO, and an imaging lens 20 sequentially disposed from an object side to an image side along an optical axis, wherein the lens group 10 sequentially includes, from the object side to the image side along the optical axis: the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the fifth lens E5, the sixth lens E6, the seventh lens E7, the eighth lens E8, and the ninth lens E9. The imaging system further includes an imaging plane disposed on the image side of the imaging lens 20.

The first lens element E1 has negative refractive power, wherein an object-side surface S1 thereof is convex, and an image-side surface S2 thereof is concave. The second lens element E2 has positive refractive power, wherein an object-side surface S2 thereof is convex, and an image-side surface S3 thereof is concave. The third lens element E3 has positive refractive power, wherein an object-side surface S4 thereof is convex, and an image-side surface S5 thereof is concave. The fourth lens element E4 has positive refractive power, wherein an object-side surface S6 thereof is convex, and an image-side surface S7 thereof is concave. The fifth lens element E5 has negative refractive power, wherein an object-side surface S8 thereof is concave, an image-side surface S9 thereof is convex, the sixth lens element E6 has positive refractive power, an object-side surface S10 thereof is convex, an image-side surface S11 thereof is convex, the seventh lens element has negative refractive power, an object-side surface S11 thereof is concave, an image-side surface S12 thereof is convex, the eighth lens element has positive refractive power, an object-side surface S13 thereof is convex, an image-side surface S14 thereof is convex, a ninth lens element has negative refractive power, an object-side surface S15 thereof is concave, and an image-side surface S16 thereof is concave. Light from the object sequentially passes through the respective surfaces S1 to S16 of the lens group 10 and the respective surfaces of the lenses of the imaging lens 20, and is finally imaged on the imaging surface S17.

The first lens element E1 to the third lens element E3, and the fifth lens element E5 to the eighth lens element E8 are made of glass.

Table 3 shows the basic parameter table of the imaging system of example 2, wherein the radius of curvature, thickness/distance, and focal length are all in millimeters (mm).

/>

TABLE 3 Table 3

In this embodiment, the total effective focal length f of the imaging system is 21.50mm, the distance TTL between the object side surface S1 of the first lens E1 and the imaging surface S17 on the optical axis is 65.00mm, the half of the diagonal length ImgH of the effective pixel area on the imaging surface S17 is 3.51mm, and the maximum half field angle Semi-FOV of the imaging system is 9.3 °.

Table 4 shows the higher order coefficients A4, A6, A8, a10, a12, a14, and a16 that can be used for each mirror of the aspherical surfaces S6 and S7 and S15 and S16 in embodiment 2, wherein each aspherical surface profile can be defined by the formula (1) given in embodiment 1 above.

Face number

A4

A6

A8

A10

A12

A14

A16

S6

-2.3737E-01

-4.2847E-02

-8.4476E-03

-1.6860E-03

-3.3719E-04

-7.8632E-05

-2.3990E-05

S7

-1.2604E-01

-4.7435E-02

-1.9146E-02

-7.7481E-03

-2.8466E-03

-8.7103E-04

-1.5836E-04

S15

-3.2237E-01

2.1712E-02

-8.8990E-04

-1.2267E-04

7.0196E-05

-2.7027E-05

1.9064E-06

S16

-2.5891E-01

2.2633E-02

-1.4950E-03

-1.6709E-05

5.4704E-05

-4.0144E-05

3.2811E-06

TABLE 4 Table 4

Fig. 5A shows an astigmatism curve of the imaging system of embodiment 2, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 5B shows a distortion curve of the imaging system of embodiment 2, which represents distortion magnitude values corresponding to different image heights. Fig. 5C shows an on-axis chromatic aberration curve for the imaging system of example 2, which indicates the focus offset of light rays of different wavelengths after passing through the imaging system. As can be seen from fig. 5A to 5C, the imaging lens system according to embodiment 2 can achieve good imaging quality.

Example 3

An imaging system according to embodiment 3 of the present application is described below with reference to fig. 6 to 7C. As shown in fig. 6, the imaging system includes a lens group 10, a stop STO, and an imaging lens 20 sequentially disposed from an object side to an image side along an optical axis, wherein the lens group 10 sequentially includes, from the object side to the image side along the optical axis: the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the fifth lens E5, the sixth lens E6, the seventh lens E7, the eighth lens E8, and the ninth lens E9. The imaging system further includes an imaging plane disposed on the image side of the imaging lens 20.

Table 5 shows the basic parameter table of the imaging system of example 3, wherein the radius of curvature, thickness/distance, and focal length are all in millimeters (mm).

TABLE 5

In this embodiment, the total effective focal length f of the imaging system is 23.23mm, the distance TTL between the object side surface S1 of the first lens E1 and the imaging surface S17 on the optical axis is 56.60mm, the half of the diagonal length ImgH of the effective pixel area on the imaging surface S17 is 3.43mm, and the maximum half field angle Semi-FOV of the imaging system is 8.5 °.

Table 6 shows the higher order coefficients A4, A6, A8, a10, and a12 that can be used for each mirror of the aspherical surfaces S8 and S9 and S13 and S14 in embodiment 3, wherein each aspherical surface profile can be defined by the formula (1) given in embodiment 1 above.

Face number	A4	A6	A8	A10	A12
						S8	-7.2606E-01	-8.5092E-02	-1.3796E-02	-3.3911E-03	-5.5553E-04
S9	-3.1392E-01	-4.4130E-02	-5.8858E-03	-7.0481E-04	-7.1005E-05
						S13	-1.1719E-01	-1.5087E-02	-5.5249E-03	-3.1387E-03	-6.4717E-04
S14	4.4415E-01	5.3554E-03	-36114E-03	-2.5687E-03	-5.3136E-04

TABLE 6

Fig. 7A shows an astigmatism curve of the imaging system of embodiment 3, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 7B shows a distortion curve of the imaging system of embodiment 3, which represents distortion magnitude values corresponding to different image heights. Fig. 7C shows an on-axis chromatic aberration curve for the imaging system of example 3, which indicates the focus offset of light rays of different wavelengths after passing through the imaging system. As can be seen from fig. 7A to fig. 7C, the imaging lens system according to embodiment 3 can achieve good imaging quality.

Example 4

An imaging system according to embodiment 4 of the present application is described below with reference to fig. 8 to 9C. As shown in fig. 8, the imaging system includes a lens group 10, a stop STO, and an imaging lens 20 sequentially disposed from an object side to an image side along an optical axis, wherein the lens group 10 sequentially includes, from the object side to the image side along the optical axis: the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the fifth lens E5, the sixth lens E6, the seventh lens E7, the eighth lens E8, and the ninth lens E9. The imaging system further includes an imaging plane disposed on the image side of the imaging lens 20.

Table 7 shows the basic parameter table of the imaging system of example 4, in which the radius of curvature, thickness/distance, and focal length are all in millimeters (mm).

TABLE 7

In this embodiment, the total effective focal length f of the imaging system is 22.67mm, the distance TTL between the object side surface S1 of the first lens E1 and the imaging surface S17 on the optical axis is 57.48mm, the half of the diagonal length ImgH of the effective pixel area on the imaging surface S17 is 3.33mm, and the maximum half field angle Semi-FOV of the imaging system is 8.5 °.

Table 8 shows the higher order coefficients A4, A6, A8, a10, and a12 that can be used for each mirror of the aspherical surfaces S8 and S9 and S13 and S14 in embodiment 4, wherein each aspherical surface profile can be defined by the formula (1) given in embodiment 1 above.

Face number	A4	A6	A8	A10	A12
						S8	-7.2612E-01	-8.4264E-02	-1.4125E-02	-3.6258E-03	-6.0721E-04
S9	-3.1446E-01	-4.4190E-02	-5.9004E-03	-7.2021E-04	-7.6661E-05
						S13	-1.2331E-01	-1.4936E-02	-5.0612E-03	-3.0949E-03	-6.3788E-04
S14	4.4408E-01	5.8904E-03	-3.0516E-03	-2.4557E-03	-5.3133E-04

TABLE 8

Fig. 9A shows an astigmatism curve of the imaging system of embodiment 4, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 9B shows a distortion curve of the imaging system of embodiment 4, which represents distortion magnitude values corresponding to different image heights. Fig. 9C shows an on-axis chromatic aberration curve for the imaging system of example 4, which indicates the focus offset of light rays of different wavelengths after passing through the imaging system. As can be seen from fig. 9A to 9C, the imaging lens system according to embodiment 4 can achieve good imaging quality.

Example 5

An imaging system according to embodiment 5 of the present application is described below with reference to fig. 10 to 11C. As shown in fig. 9, the imaging system includes a lens group 10, a stop STO, and an imaging lens 20 sequentially disposed from an object side to an image side along an optical axis, wherein the lens group 10 sequentially includes, from the object side to the image side along the optical axis: the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the fifth lens E5, the sixth lens E6, the seventh lens E7, the eighth lens E8, and the ninth lens E9. The imaging system further includes an imaging plane disposed on the image side of the imaging lens 20.

The first lens element E1 has positive refractive power, wherein an object-side surface S1 thereof is convex, and an image-side surface S2 thereof is convex. The second lens element E2 has negative refractive power, wherein an object-side surface S2 thereof is concave, and an image-side surface S3 thereof is concave. The third lens element E3 has positive refractive power, wherein an object-side surface S4 thereof is convex, and an image-side surface S5 thereof is convex. The fourth lens element E4 has positive refractive power, wherein an object-side surface S6 thereof is convex, and an image-side surface S7 thereof is concave. The fifth lens element E5 has negative refractive power, wherein an object-side surface S8 thereof is convex, an image-side surface S9 thereof is concave, the sixth lens element E6 has positive refractive power, an object-side surface S10 thereof is concave, an image-side surface S11 thereof is convex, the seventh lens element has negative refractive power, an object-side surface S11 thereof is concave, an image-side surface S12 thereof is convex, the eighth lens element has positive refractive power, an object-side surface S13 thereof is convex, an image-side surface S14 thereof is convex, a ninth lens element has positive refractive power, an object-side surface S15 thereof is convex, and an image-side surface S16 thereof is convex. Light from the object sequentially passes through the respective surfaces S1 to S16 of the lens group 10 and the respective surfaces of the lenses of the imaging lens 20, and is finally imaged on the imaging surface S17.

The first lens element E1 to the fourth lens element E4, the sixth lens element E6 and the ninth lens element E9 are made of glass.

Table 9 shows a basic parameter table of the imaging system of example 5, in which the radius of curvature, thickness/distance, and focal length are all in millimeters (mm).

TABLE 9

In this embodiment, the total effective focal length f of the imaging system is 17.82mm, the distance TTL between the object side surface S1 of the first lens E1 and the imaging surface S17 on the optical axis is 63.75mm, the half of the diagonal length ImgH of the effective pixel area on the imaging surface S17 is 2.46mm, and the maximum half field angle Semi-FOV of the imaging system is 8.5 °.

Table 10 shows the higher order coefficients A4, A6, A8, a10, and a12 that can be used for each mirror of the aspherical surfaces S8 and S9 and S13 and S14 in embodiment 5, wherein each aspherical surface profile can be defined by the formula (1) given in embodiment 1 above.

Face number	A4	A6	A8	A10	A12
						S8	-7.4353E-01	-8.4928E-02	-1.2531E-02	-2.8856E-03	-4.1270E-04
S9	-3.1666E-01	-4.3154E-02	-5.5426E-03	-6.8706E-04	-6.2214E-05
						S13	4.8746E-03	6.9614E-02	6.7611E-03	-1.7475E-04	1.5665E-04
S14	5.5218E-01	1.0564E-01	2.0369E-02	3.2870E-03	76609E-04

Table 10

Fig. 11A shows an astigmatism curve of the imaging system of example 5, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 11B shows a distortion curve of the imaging system of example 5, which represents the magnitude of distortion corresponding to different image heights. Fig. 11C shows an on-axis chromatic aberration curve for the imaging system of example 5, which indicates the focus offset of light rays of different wavelengths after passing through the imaging system. As can be seen from fig. 11A to 11C, the imaging system lens provided in embodiment 5 can achieve good imaging quality.

Example 6

An imaging system according to embodiment 6 of the present application is described below with reference to fig. 12 to 13C. As shown in fig. 12, the imaging system includes a lens group 10, a stop STO, and an imaging lens 20 sequentially disposed from an object side to an image side along an optical axis, wherein the lens group 10 sequentially includes, from the object side to the image side along the optical axis: the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the fifth lens E5, the sixth lens E6, the seventh lens E7, the eighth lens E8, and the ninth lens E9. The imaging system further includes an imaging plane disposed on the image side of the imaging lens 20.

The first lens element E1 to the fourth lens element E4 and the sixth lens element E6 are made of glass.

Table 11 shows the basic parameter table of the imaging system of example 6, in which the radius of curvature, thickness/distance, and focal length are all in millimeters (mm).

TABLE 11

In this embodiment, the total effective focal length f of the imaging system is 17.89mm, the distance TTL between the object side surface S1 of the first lens E1 and the imaging surface S17 on the optical axis is 65.01mm, the half of the diagonal length ImgH of the effective pixel area on the imaging surface S17 is 2.51mm, and the maximum half field angle Semi-FOV of the imaging system is 8.5 °.

Table 12 shows the higher order coefficients A4, A6, A8, a10, and a12 that can be used for each mirror of the aspherical surfaces S8 and S9 and S13 and S14 in embodiment 6, wherein each aspherical surface profile can be defined by the formula (1) given in embodiment 1 above.

Face number	A4	A6	A8	A10	A12
						S8	-7.4586E-01	-8.2589E-02	-1.2454E-02	-3.2680E-03	-5.7191E-04
S9	-3.0921E-01	-4.1712E-02	-5.2960E-03	-6.6463E-04	-7.3631E-05
						S13	9.5809E-02	4.9543E-02	6.7977E-03	1.1050E-03	6.7641E-04
S14	71128E-01	1.1529E-01	2.5424E-02	6.1312E-03	1.6298E-03

Table 12

Fig. 13A shows an astigmatism curve of the imaging system of example 6, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 13B shows a distortion curve of the imaging system of example 6, which represents the magnitude of distortion corresponding to different image heights. Fig. 13C shows an on-axis chromatic aberration curve for the imaging system of example 6, which indicates the focus offset of light rays of different wavelengths after passing through the imaging system. As can be seen from fig. 13A to 13C, the imaging system lens provided in embodiment 6 can achieve good imaging quality.

Example 7

An imaging system according to embodiment 7 of the present application is described below with reference to fig. 14 to 15C. As shown in fig. 14, the imaging system includes a lens group 10, a stop STO, and an imaging lens 20 sequentially disposed from an object side to an image side along an optical axis, wherein the lens group 10 sequentially includes, from the object side to the image side along the optical axis: the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the fifth lens E5, the sixth lens E6, the seventh lens E7, the eighth lens E8, and the ninth lens E9. The imaging system further includes an imaging plane disposed on the image side of the imaging lens 20.

The first lens element E1 has positive refractive power, wherein an object-side surface S1 thereof is convex, and an image-side surface S2 thereof is convex. The second lens element E2 has negative refractive power, wherein an object-side surface S2 thereof is concave, and an image-side surface S3 thereof is concave. The third lens element E3 has positive refractive power, wherein an object-side surface S4 thereof is convex, and an image-side surface S5 thereof is convex. The fourth lens element E4 has positive refractive power, wherein an object-side surface S6 thereof is convex, and an image-side surface S7 thereof is concave. The fifth lens element E5 has negative refractive power, wherein an object-side surface S8 thereof is convex, an image-side surface S9 thereof is concave, the sixth lens element E6 has positive refractive power, an object-side surface S10 thereof is concave, an image-side surface S11 thereof is convex, the seventh lens element has negative refractive power, an object-side surface S11 thereof is concave, an image-side surface S12 thereof is convex, the eighth lens element has positive refractive power, an object-side surface S13 thereof is convex, an image-side surface S14 thereof is concave, a ninth lens element has positive refractive power, an object-side surface S15 thereof is convex, and an image-side surface S16 thereof is convex. Light from the object sequentially passes through the respective surfaces S1 to S16 of the lens group 10 and the respective surfaces of the lenses of the imaging lens 20, and is finally imaged on the imaging surface S17.

Table 13 shows a basic parameter table of the imaging system of example 7, in which the radius of curvature, thickness/distance, and focal length are all in millimeters (mm).

TABLE 13

In this embodiment, the total effective focal length f of the imaging system is 16.60mm, the distance TTL between the object side surface S1 of the first lens E1 and the imaging surface S17 on the optical axis is 67.44mm, the half of the diagonal length ImgH of the effective pixel area on the imaging surface S17 is 2.32mm, and the maximum half field angle Semi-FOV of the imaging system is 8.5 °.

Table 14 shows the higher order coefficients A4, A6, A8, a10, and a12 that can be used for each mirror of the aspherical surfaces S8 and S9 and S13 and S14 in example 7, wherein each aspherical surface profile can be defined by the formula (1) given in example 1 above.

TABLE 14

Fig. 15A shows an astigmatism curve of the imaging system of example 7, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 15B shows a distortion curve of the imaging system of example 7, which represents the magnitude of distortion corresponding to different image heights. Fig. 15C shows an on-axis chromatic aberration curve for the imaging system of example 7, which represents the focus offset of light rays of different wavelengths after passing through the imaging system. As can be seen from fig. 15A to 15C, the imaging system lens provided in embodiment 7 can achieve good imaging quality.

Example 8

An imaging system according to embodiment 8 of the present application is described below with reference to fig. 16 to 17C. As shown in fig. 16, the imaging system includes a lens group 10, a stop STO, and an imaging lens 20 disposed in order from an object side to an image side along an optical axis, wherein the lens group 10 includes, in order from the object side to the image side along the optical axis: the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the fifth lens E5, the sixth lens E6, the seventh lens E7, the eighth lens E8, and the ninth lens E9. The imaging system further includes an imaging plane disposed on the image side of the imaging lens 20.

The first lens element E1 to the third lens element E3 and the sixth lens element E6 are made of glass.

Table 15 shows a basic parameter table of the imaging system of example 8, in which the radius of curvature, thickness/distance, and focal length are all in millimeters (mm).

TABLE 15

In this embodiment, the total effective focal length f of the imaging system is 15.96mm, the distance TTL between the object side surface S1 of the first lens E1 and the imaging surface S17 on the optical axis is 68.33mm, the half of the diagonal length ImgH of the effective pixel area on the imaging surface S17 is 2.24mm, and the maximum half field angle Semi-FOV of the imaging system is 8.5 °.

Table 16 shows the higher order coefficients A4, A6, A8, a10, and a12 that can be used for each mirror of the aspherical surfaces S8 and S9 and S13 and S14 in embodiment 8, wherein each aspherical surface profile can be defined by the formula (1) given in embodiment 1 above.

Face number	A4	A6	A8	A10	A12
						S8	-7.3128E-01	-8.3880E-02	-1.7323E-02	-4.5845E-03	-7.2121E-04
S9	-2.9426E-01	-3.9044E-02	-5.6686E-03	-8.0196E-04	-1.2046E-04
						S13	-1.8628E-01	6.0850E-02	1.5734E-02	3.4432E-03	7.0343E-05
S14	4.8997E-01	1.1863E-01	3.4939E-02	9.1228E-03	1.9285E-03

Table 16

Fig. 17A shows an astigmatism curve of the imaging system of embodiment 8, which represents meridional image plane curvature and sagittal image plane curvature. Fig. 17B shows a distortion curve of the imaging system of example 8, which represents the magnitude of distortion corresponding to different image heights. Fig. 17C shows an on-axis chromatic aberration curve for the imaging system of example 8, which represents the focus offset of light rays of different wavelengths after passing through the imaging system. As can be seen from fig. 17A to 17C, the imaging system lens provided in embodiment 8 can achieve good imaging quality.

In summary, examples 1 to 8 each satisfy the relationship shown in table 17.

TABLE 17

The foregoing description is only of the preferred embodiments of the present application and is presented as a description of the principles of the technology being utilized. It should be understood by those skilled in the art that the scope of the invention referred to in this application is not limited to the specific combination of the above technical features, but also encompasses other technical features formed by any combination of the above technical features or their equivalents without departing from the inventive concept. Such as the above-described features and technical features having similar functions (but not limited to) disclosed in the present application are replaced with each other.

Claims

1. An imaging system including a lens group including, in order from an object side to an image side along an optical axis, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens having optical power, characterized in that,

the combined focal length of the first lens and the second lens has positive focal power, wherein the effective diameter part of the object side surface of the first lens is in a convex shape on the surface of the effective diameter part, and the image side surface of the second lens is a concave surface;

The third lens has positive focal power, and the object side surface of the third lens is a convex surface;

the object side surface of the fourth lens is a convex surface, and the image side surface is a concave surface;

the image side surfaces of at least three lenses from the first lens to the fifth lens are concave surfaces;

the fifth lens is a meniscus lens;

the image side surface of the seventh lens is a convex surface;

the eighth lens has positive focal power, and the object side surface of the eighth lens is a convex surface;

the ninth lens is a biconvex lens or a biconcave lens;

the number of lenses of the lens group with optical power is nine; the first lens and the second lens are cemented lenses, and the sixth lens and the seventh lens are cemented lenses;

the imaging system further comprises an imaging lens located at the image side of the ninth lens; and

the imaging system satisfies: 1.0<TD/f<4.0，0.7<Σ ⁴ _i=1 |CT _i -CT _i+1 |/(CT _i +CT _i+1 )<1.5 and i is an integer from 1 to 4,

wherein, TD is the distance between the object side surface of the first lens and the image side surface of the ninth lens on the optical axis, f is the total effective focal length of the lens group formed by the first lens and the ninth lens, CT _i CT for the center thickness of the ith lens from the first lens to the ninth lens on the optical axis _i+1 Is the center thickness of the i+1th lens of the first to ninth lenses on the optical axis.

2. The imaging system of claim 1, wherein the imaging system satisfies: 40.0mm < TTL <70.0mm, wherein TTL is the distance between the object side surface of the first lens and the imaging surface of the imaging lens on the optical axis.

3. The imaging system of claim 1, wherein the imaging lens comprises a plurality of lenses.

4. The imaging system of any of claims 1 to 3, wherein the imaging system satisfies: 40.0< (f12+f67)/(f12-f 67) <20.0,

wherein f12 is a combined focal length of the first lens and the second lens, and f67 is a combined focal length of the sixth lens and the seventh lens.

5. The imaging system of any of claims 1 to 3, wherein the imaging system satisfies:

0<T56/T89<2.5，

wherein T56 is an air space on the optical axis between the fifth lens and the sixth lens, and T89 is an air space on the optical axis between the eighth lens and the ninth lens.

6. The imaging system of any of claims 1 to 3, wherein the imaging system satisfies:

0<f3/f8<3.0，

wherein f3 is an effective focal length of the third lens, and f8 is an effective focal length of the eighth lens.

7. The imaging system of any of claims 1 to 3, wherein the imaging system satisfies: 2.0< R4/R1<12.0, wherein R1 is the radius of curvature of the object-side surface of the first lens and R4 is the radius of curvature of the image-side surface of the second lens.

8. The imaging system of any of claims 1 to 3, wherein the imaging system satisfies: 0< R5/(R7+R8) <5.0,

wherein R5 is a radius of curvature of an object side surface of the third lens element, R7 is a radius of curvature of an object side surface of the fourth lens element, and R8 is a radius of curvature of an image side surface of the fourth lens element.

9. The imaging system of any of claims 1 to 3, wherein the imaging system satisfies: R14/R15 > -2.5,

wherein R14 is a radius of curvature of an image side surface of the seventh lens element, and R15 is a radius of curvature of an object side surface of the eighth lens element.

10. The imaging system of any of claims 1 to 3, wherein the imaging system satisfies: 1.0< (R14+R15)/(R14-R15) <1.0,

11. The imaging system according to any one of claims 1 to 3, wherein at least four lenses of the first lens to the ninth lens are spherical lenses made of glass.

12. The imaging system according to any one of claims 1 to 3, wherein at least three lenses of the first to fifth lenses are spherical lenses made of glass.

13. The imaging system of any of claims 1 to 3, wherein the imaging system satisfies: 0.4< N7/(N8+N9) <0.7,

wherein N7 is the refractive index of the seventh lens, N8 is the refractive index of the eighth lens, and N9 is the refractive index of the ninth lens.

14. The imaging system of any of claims 1 to 3, wherein the imaging system satisfies: 0.4< V9/[ (V7+V8)/2 ] <2.5,

wherein V7 is an abbe number of the seventh lens, N8 is an abbe number of the eighth lens, and N9 is an abbe number of the ninth lens.

15. The imaging system of any of claims 1 to 3, wherein the imaging system satisfies: 1.5< (N1+N2+N3+N4+N5)/5 < 1.72,

wherein N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, N3 is the refractive index of the third lens, N4 is the refractive index of the fourth lens, and N5 is the refractive index of the fifth lens.

16. The imaging system of any of claims 1 to 3, wherein the imaging system satisfies: 20.0< (V1+V2+V3+V4+V5)/5 <60.0,

wherein V1 is the abbe number of the first lens, V2 is the abbe number of the second lens, V3 is the abbe number of the third lens, V4 is the abbe number of the fourth lens, and V5 is the abbe number of the fifth lens.

17. The imaging system of any of claims 1 to 3, wherein at least two pairs of adjacent lenses in the imaging system are cemented lenses.

18. The imaging system according to any one of claims 1 to 3, wherein a radius of curvature of one of an image side surface of the fifth lens and an object side surface of the sixth lens is positive, and a radius of curvature of the other is negative.

19. The imaging system of any of claims 1 to 3, wherein the imaging system satisfies:

0<(CT6+CT7)/(CT8+CT9)<2.0，

wherein, CT6 is the center thickness of the sixth lens on the optical axis, CT7 is the center thickness of the seventh lens on the optical axis, CT8 is the center thickness of the eighth lens on the optical axis, and CT9 is the center thickness of the ninth lens on the optical axis.

20. An electronic device comprising an imaging system as claimed in any one of claims 1 to 19.