CN114578523B

CN114578523B - Optical lens

Info

Publication number: CN114578523B
Application number: CN202210489344.8A
Authority: CN
Inventors: 章彬炜; 钟培森; 曾昊杰
Original assignee: Jiangxi Lianyi Optics Co Ltd
Current assignee: Jiangxi Lianyi Optics Co Ltd
Priority date: 2022-05-07
Filing date: 2022-05-07
Publication date: 2022-09-23
Anticipated expiration: 2042-05-07
Also published as: CN114578523A

Abstract

The invention discloses an optical lens, which comprises the following components in sequence from an object side to an imaging surface along an optical axis: a diaphragm; a first lens element having a positive optical power, an object-side surface being convex and an image-side surface being concave at a paraxial region; a second lens with negative focal power, wherein the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; a third lens having a positive refractive power, an object-side surface of which is convex; a fourth lens having a focal power; a fifth lens element having a refractive power, the object-side surface of the fifth lens element being concave and the image-side surface of the fifth lens element being convex; a sixth lens element having a focal power, an object-side surface being convex at a paraxial region and an image-side surface being concave at the paraxial region; a seventh lens having a power, an object-side surface of which is convex at a paraxial region and an image-side surface of which is concave at a paraxial region; and the object side surface of the eighth lens with negative focal power is a concave surface. The optical lens has the advantages of large aperture, high pixel and compact structure.

Description

Optical lens

Technical Field

The invention relates to the technical field of imaging lenses, in particular to an optical lens.

Background

Today, the technological progress is fast, and the iterative updating of electronic products brings great convenience to the life of people. The imaging performance of the camera, which is one of the important parameters of electronic products, has been the focus of attention of manufacturers and users, and the requirements of users for shooting also range from clear shooting to good shooting. Generally, the large-size high pixels enable the photo to have more information, the higher the definition of the photo, and the more convenient the post-retouching. The progress of the imaging chip is a precondition for the appearance of large-size high-pixel equipment, a hundred million ultrahigh-pixel large-substrate chip is provided at present, but the debugging of the chip is difficult, a 50M-pixel large-size chip is still the first choice of the current mainstream equipment, and a high-pixel lens matched with a large-size sensor chip becomes one of important competitive indexes of flagship machines of various portable electronic equipment manufacturers.

In order to ensure the improvement of pixels, the size of pixel points of the sensor chip is not reduced, and the increase of the size of the sensor chip becomes an important development trend of high pixels. However, most electronic devices still use lenses with lower pixels, and the electronic devices with 50M large-sized high-pixel lenses are only a few, and have a large volume, and the imaging quality of the lenses with large aperture is difficult to meet the market demand.

Disclosure of Invention

Therefore, the present invention is directed to provide an optical lens, which has the advantages of a large aperture, a high pixel and a compact structure, and can be used with a large-sized sensor chip to meet the requirement of a consumer for image capture.

The embodiment of the invention implements the above object by the following technical scheme.

The invention provides an optical lens, which sequentially comprises the following components from an object side to an imaging surface along an optical axis: a diaphragm; a first lens having positive optical power, the first lens having a convex object-side surface and a concave image-side surface at a paraxial region; the second lens with negative focal power is characterized in that the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; a third lens having a positive optical power, an object side surface of the third lens being convex; a fourth lens having an optical power; the lens comprises a fifth lens with focal power, wherein the object side surface of the fifth lens is a concave surface, and the image side surface of the fifth lens is a convex surface; a sixth lens having a optical power, an object-side surface of the sixth lens being convex at a paraxial region, an image-side surface of the sixth lens being concave at a paraxial region; a seventh lens having a power, an object side surface of the seventh lens being convex at a paraxial region, an image side surface of the seventh lens being concave at a paraxial region; an eighth lens having a negative optical power, an object side surface of the eighth lens being concave.

Compared with the prior art, the optical lens provided by the invention is composed of eight aspheric plastic lenses with specific surface shapes, and reasonable focal power distribution and diaphragm arrangement are adopted, so that the optical lens has the characteristics of high pixel, large aperture and compact structure, and meanwhile, the optical lens can be matched with a large-size sensor chip (such as the large size of 50M pixels), so that the imaging of the optical lens is clearer when the optical lens works in a dark environment or an environment with sufficient light.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic structural diagram of an optical lens according to a first embodiment of the present invention;

FIG. 2 is a field curvature graph of an optical lens according to a first embodiment of the present invention;

FIG. 3 is a distortion curve diagram of an optical lens according to a first embodiment of the present invention;

FIG. 4 is a graph of axial spherical aberration of an optical lens according to a first embodiment of the present invention;

FIG. 5 is a lateral chromatic aberration diagram of an optical lens according to a first embodiment of the present invention;

FIG. 6 is a schematic structural diagram of an optical lens system according to a second embodiment of the present invention;

FIG. 7 is a field curvature graph of an optical lens according to a second embodiment of the present invention;

FIG. 8 is a distortion curve diagram of an optical lens according to a second embodiment of the present invention;

FIG. 9 is a graph of on-axis spherical aberration curves of an optical lens according to a second embodiment of the present invention;

FIG. 10 is a lateral chromatic aberration diagram of an optical lens according to a second embodiment of the present invention;

FIG. 11 is a schematic structural diagram of an optical lens assembly according to a third embodiment of the present invention;

FIG. 12 is a field curvature graph of an optical lens according to a third embodiment of the present invention;

fig. 13 is a distortion graph of an optical lens according to a third embodiment of the present invention;

FIG. 14 is a graph of on-axis spherical aberration of an optical lens according to a third embodiment of the present invention;

FIG. 15 is a lateral chromatic aberration diagram of an optical lens according to a third embodiment of the present invention;

FIG. 16 is a schematic structural diagram of an optical lens assembly according to a fourth embodiment of the present invention;

FIG. 17 is a field curvature graph of an optical lens according to a fourth embodiment of the present invention;

fig. 18 is a distortion graph of an optical lens according to a fourth embodiment of the present invention;

FIG. 19 is a graph showing an on-axis spherical aberration of an optical lens according to a fourth embodiment of the present invention;

FIG. 20 is a lateral chromatic aberration diagram of an optical lens according to a fourth embodiment of the present invention;

FIG. 21 is a schematic structural diagram of an optical lens assembly according to a fifth embodiment of the present invention;

FIG. 22 is a field curvature graph of an optical lens according to a fifth embodiment of the present invention;

fig. 23 is a distortion graph of an optical lens according to a fifth embodiment of the present invention;

FIG. 24 is a graph showing an on-axis spherical aberration of an optical lens according to the fifth embodiment of the present invention;

fig. 25 is a lateral chromatic aberration diagram of an optical lens according to a fifth embodiment of the present invention.

Detailed Description

In order to make the objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. Several embodiments of the invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Like reference numerals refer to like elements throughout the specification.

The present invention provides an optical lens, sequentially including, from an object side to an image plane along an optical axis: the lens comprises a diaphragm, 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 filter.

Wherein the first lens has a positive optical power, the first lens has a convex object-side surface, and the first lens has a concave image-side surface at a paraxial region;

the second lens has negative focal power, the object side surface of the second lens is a convex surface, 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 fourth lens has optical power;

the fifth lens has focal power, the object side surface of the fifth lens is a concave surface, and the image side surface of the fifth lens is a convex surface;

the sixth lens has a power, an object-side surface of the sixth lens being convex at a paraxial region, and an image-side surface of the sixth lens being concave at a paraxial region;

the seventh lens has a power, an object side surface of the seventh lens being convex at a paraxial region, and an image side surface of the seventh lens being concave at a paraxial region;

the eighth lens has negative focal power, and the object side surface of the eighth lens is a concave surface.

In some embodiments, the optical lens satisfies the following conditional expression:

6mm<IH<7mm；(1)

1.6<f/EPD<2.0；(2)

wherein IH represents an actual half-image height of the optical lens, f represents an effective focal length of the optical lens, and EPD represents an entrance pupil diameter of the optical lens. Satisfying conditional expressions (1) and (2) enables the optical lens to more easily satisfy a high pixel requirement of 50M, and enables the optical lens to have a characteristic of a large aperture while satisfying the high pixel. If IH exceeds the conditional expression (1), the pixels of the optical lens cannot meet the design requirements, and the market competitiveness is weakened; when the f/EPD is more than 1.6 and less than 2.0, the light flux amount of the optical lens is increased, so that the optical lens can have better imaging capability in a dark environment, and the effect of background blurring can be enhanced in normal illumination shooting.

6.12 mm<f*tanθ<6.14 mm；(3)

wherein f represents an effective focal length of the optical lens, and θ represents a maximum half field angle of the optical lens. The distortion of the optical lens is well corrected, so that the imaging of the optical lens is closer to a real scene, the image quality degradation of the edge is smaller, and the attenuation of the imaging quality increased along with the image height is inhibited; meanwhile, large image surface characteristics can be realized, so that the large-size photosensitive element can be matched, and the optical lens has the characteristics of high pixels and high definition.

2.195<DM82/DM12<2.69；(4)

wherein DM82 represents the maximum effective diameter of the image-side surface of the eighth lens, and DM12 represents the maximum effective diameter of the image-side surface of the first lens. The method meets the conditional expression (4), is favorable for controlling the projection height of light on the image surface, ensures the high pixel of the optical lens, simultaneously avoids the light from deflecting too fast, and ensures that the optical lens has good imaging quality when the aperture is large.

9.75<TTL/BFL<14.66；(5)

wherein, TTL represents the optical total length of the optical lens, and BFL represents the optical back focus of the optical lens. And the condition formula (5) is met, the optical back focus of the optical lens can be reasonably controlled, the interference of the optical lens and a chip in the assembling process can be avoided, enough space is reserved for assembling, and the yield in the production process is favorably ensured.

1.07<CT34/(CT3+CT4)<1.21；(6)

wherein CT34 denotes a distance on an optical axis from an image-side surface of the third lens to an object-side surface of the fourth lens, CT3 denotes a center thickness of the third lens, and CT4 denotes a center thickness of the fourth lens. The shape of the third lens and the shape of the fourth lens can be effectively controlled to bear certain positive focal power in an optical system when the conditional expression (6) is met, so that the trend of light deflection is accelerated, and the compactness and the miniaturization of the optical lens structure are realized.

-0.71<(SAG41+SAG42)/ET4<1.24；（7）

-2.43<SAG61/CT6<-0.335；(8)

wherein SAG41 represents the sagged height of the object side of the fourth lens, SAG42 represents the sagged height of the image side of the fourth lens, ET4 represents the edge thickness of the fourth lens, SAG61 represents the sagged height of the object side of the sixth lens, and CT6 represents the center thickness of the sixth lens. The condition formula (7) is met, the processing difficulty of the fourth lens is reduced, and the field curvature and the edge aberration can be better modified; the conditional expression (8) is satisfied, the rise and thickness ratio of the sixth lens can be effectively controlled, the lens manufacturing and forming are facilitated, and the manufacturing yield is improved.

1.72 mm<DT11/tanθ<2.17 mm；(9)

where DT11 denotes a maximum effective half diameter of an object-side surface of the first lens, and θ denotes a maximum half field angle of the optical lens. The effective aperture of the lens at the head of the lens can be well controlled, the resolving power of the edge of the lens is effectively improved, a large aperture is guaranteed, meanwhile, a sufficient visual range can be obtained, and the small depth of the field of view of the lens and the large windowing are guaranteed.

1.36<(R21+R22)/f<3.96；（10）

wherein R21 denotes a radius of curvature of an object side surface of the second lens, R22 denotes a radius of curvature of an image side surface of the second lens, and f denotes an effective focal length of the optical lens. And the condition expression (10) is satisfied, so that the sensitivity of the second lens can be reduced, the aberration of the system can be better corrected, and the convergence of the field curvature is facilitated.

0.97<(CT2+CT3+CT4+CT5)/(ET2+ET3+ET4+ET5)<1.35；(11)

wherein CT2 denotes a center thickness of the second lens, CT3 denotes a center thickness of the third lens, CT4 denotes a center thickness of the fourth lens, CT5 denotes a center thickness of the fifth lens, ET2 denotes an edge thickness of the second lens, ET3 denotes an edge thickness of the third lens, ET4 denotes an edge thickness of the fourth lens, and ET5 denotes an edge thickness of the fifth lens. The curved surface shapes of the second lens, the third lens, the fourth lens and the fifth lens can be reasonably limited by satisfying the conditional expression (11), thereby being beneficial to the molding of the four lenses, reducing the processing sensitivity and simultaneously being beneficial to the optimization of aberration and the convergence of field curvature.

0.16<(SAG61+SAG71)/(SAG62+SAG72)<0.48；(12)

wherein SAG61 represents the saggital height of the object-side surface of the sixth lens, SAG71 represents the saggital height of the object-side surface of the seventh lens, SAG62 represents the saggital height of the image-side surface of the sixth lens, and SAG72 represents the saggital height of the image-side surface of the seventh lens. The method satisfies the conditional expression (12), can reasonably control the surface type of the lens, reduces the difficulty in processing, is beneficial to the convergence of the aberration of the optical system, and improves the imaging quality of the optical system.

-17.67 mm<(Nd3*f2)/Nd1<-8.94 mm；(13)

where Nd3 denotes a refractive index of the third lens, f2 denotes an effective focal length of the second lens, and Nd1 denotes a refractive index of the first lens. The optical lens meets the conditional expression (13), the total length of the optical lens can be shortened while the lens has high pixels by reasonably selecting the materials of the first lens and the third lens, and meanwhile, the aberration of the optical system can be corrected by properly balancing the focal power of the second lens, so that the imaging quality is improved, and the system structure is kept compact.

In some embodiments, the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element, the sixth lens element, the seventh lens element and the eighth lens element are all plastic aspheric lens elements. Each lens adopts an aspheric lens, and the aspheric lens at least has the following three advantages: the lens has better imaging quality; the structure of the lens is more compact; the total optical length of the lens is shorter. In addition, in some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens may be all glass lenses, or a combination of plastic lenses and glass lenses.

The invention is further illustrated below in the following examples. In various embodiments, the thickness, the curvature radius, and the material selection of each lens in the optical lens are different, and the specific differences can be referred to in the parameter tables of the various embodiments. The following examples are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the following examples, and any other changes, substitutions, combinations or simplifications which do not depart from the gist of the present invention should be construed as being equivalent replacements within the scope of the present invention.

In each embodiment of the present invention, when the lens is an aspherical lens, the surface shape of the aspherical lens satisfies the following equation:

wherein z is the distance rise from the aspheric surface vertex when the aspheric surface is at the position of height h along the optical axis direction, c is the paraxial curvature of the surface, k is conic coefficient, A _2i Is the aspheric surface type coefficient of 2i order.

First embodiment

Referring to fig. 1, an optical lens 100 according to a first embodiment of the present invention includes, from an object side to an image plane S19 along an optical axis: the stop ST, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, and the filter G1.

The first lens element L1 is a plastic aspheric lens element with positive refractive power, the object-side surface S1 of the first lens element is convex, and the image-side surface S2 of the first lens element is concave at the paraxial region;

the second lens element L2 is a plastic aspheric lens with negative refractive power, the object-side surface S3 of the second lens element is convex, and the image-side surface S4 of the second lens element is concave;

the third lens element L3 is a plastic aspheric lens with positive power, the object-side surface S5 of the third lens element is convex, and the image-side surface S6 of the third lens element is concave at the paraxial region;

the fourth lens element L4 is a plastic aspheric lens with positive refractive power, the object-side surface S7 of the fourth lens element is convex, and the image-side surface S8 of the fourth lens element is concave;

the fifth lens element L5 is a plastic aspheric lens with positive refractive power, the object-side surface S9 of the fifth lens element is concave, and the image-side surface S10 of the fifth lens element is convex;

the sixth lens element L6 is a plastic aspheric lens with negative power, and has a convex object-side surface S11 and a concave image-side surface S12 at the paraxial region;

the seventh lens element L7 is a plastic aspheric lens with positive power, the object-side surface S13 of the seventh lens element is convex at the paraxial region, and the image-side surface S14 of the seventh lens element is concave at the paraxial region;

the eighth lens element L8 is a plastic aspheric lens with negative power, the object-side surface S15 of the eighth lens element is concave, and the image-side surface S16 of the eighth lens element is convex at the paraxial region;

the object-side surface of the filter G1 is S17, and the image-side surface is S18.

The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7 and the eighth lens L8 are all plastic aspheric lenses.

The parameters of the optical lens 100 provided in the present embodiment are shown in table 1, where R represents the radius of curvature (unit: mm), d represents the distance between the optical surfaces (unit: mm), and n represents the distance between the optical surfaces (unit: mm) _d D-line refractive index, V, of the representative material _d Represents the abbe number of the material.

TABLE 1

The surface shape coefficients of the aspherical surfaces of the optical lens 100 in the present embodiment are shown in table 2.

TABLE 2

In the present embodiment, the graphs of field curvature, distortion, on-axis spherical aberration and lateral chromatic aberration of the optical lens 100 are shown in fig. 2, fig. 3, fig. 4 and fig. 5, respectively, and it can be seen from fig. 2 to fig. 5 that the field curvature is controlled within ± 0.05mm, the optical distortion is controlled within ± 1.5%, the axial chromatic aberration of the shortest wavelength and the largest wavelength is controlled within ± 0.04mm, and the chromatic aberration of each wavelength relative to the central wavelength in different fields of view is controlled within ± 1 micron, which indicates that the field curvature, distortion and chromatic aberration of the optical lens 100 are well corrected.

Second embodiment

Referring to fig. 6, a schematic structural diagram of an optical lens 200 provided in this embodiment includes, from an object side to an image plane S19 along an optical axis, the optical lens 200: the stop ST, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, and the filter G1.

The first lens element L1 is a plastic aspheric lens with positive refractive power, the object-side surface S1 of the first lens element is convex, and the image-side surface S2 of the first lens element is concave at paraxial region;

the third lens element L3 is a plastic aspheric lens with positive power, the object-side surface S5 of the third lens element is convex, and the image-side surface S6 of the third lens element is convex at paraxial region;

the fourth lens element L4 is a plastic aspheric lens with positive refractive power, the object-side surface S7 of the fourth lens element is concave, and the image-side surface S8 of the fourth lens element is convex;

the fifth lens element L5 is a plastic aspheric lens with negative power, the object-side surface S9 of the fifth lens element is concave, and the image-side surface S10 of the fifth lens element is convex;

the sixth lens element L6 is a plastic aspheric lens element with positive optical power, and has an object-side surface S11 that is convex at the paraxial region and an image-side surface S12 that is concave at the paraxial region;

the seventh lens element L7 is a plastic aspheric lens with negative power, the object-side surface S13 of the seventh lens element is convex at the paraxial region, and the image-side surface S14 of the seventh lens element is concave at the paraxial region;

The present embodiment provides the relevant parameters of each lens in the optical lens 200 as shown in table 3.

TABLE 3

The surface shape coefficients of the aspherical surfaces of the optical lens 200 in the present embodiment are shown in table 4.

TABLE 4

In the present embodiment, the graphs of field curvature, distortion, on-axis spherical aberration and lateral chromatic aberration of the optical lens 200 are shown in fig. 7, fig. 8, fig. 9 and fig. 10, respectively, and it can be seen from fig. 7 to fig. 10 that the field curvature is controlled within ± 0.05mm, the optical distortion is controlled within ± 2%, the axial chromatic aberration of the shortest wavelength and the largest wavelength is controlled within ± 0.02mm, and the chromatic aberration of each wavelength with respect to the central wavelength in different fields of view is controlled within ± 2 microns, which indicates that the field curvature, distortion and chromatic aberration of the optical lens 200 are well corrected.

Third embodiment

Referring to fig. 11, a schematic structural diagram of an optical lens 300 provided in this embodiment includes, from an object side to an image plane S19 along an optical axis, the optical lens 300: the stop ST, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, and the filter G1.

the fourth lens element L4 is a plastic aspheric lens element with positive refractive power, and has a concave object-side surface S7 and a convex image-side surface S8;

the sixth lens element L6 is a plastic aspheric lens with positive power, the sixth lens element having an object-side surface S11 that is convex at the paraxial region and an image-side surface S12 that is concave at the paraxial region;

The parameters related to each lens of the optical lens 300 provided in this embodiment are shown in table 5.

TABLE 5

The surface shape coefficients of the aspherical surfaces of the optical lens 300 in the present embodiment are shown in table 6.

TABLE 6

In the present embodiment, the graphs of field curvature, distortion, on-axis spherical aberration and lateral chromatic aberration of the optical lens 300 are respectively shown in fig. 12, fig. 13, fig. 14 and fig. 15, and it can be seen from fig. 12 to fig. 15 that the field curvature is controlled within ± 0.05mm, the optical distortion is controlled within ± 2%, the axial chromatic aberration of the shortest wavelength and the largest wavelength is controlled within ± 0.03mm, and the chromatic aberration of each wavelength with respect to the central wavelength in different fields of view is controlled within ± 2 microns, which indicates that the field curvature, distortion and chromatic aberration of the optical lens 300 are well corrected.

Fourth embodiment

Referring to fig. 16, a schematic structural diagram of an optical lens 400 provided in this embodiment includes, from an object side to an image plane S19 along an optical axis, the optical lens 400: the lens system comprises a diaphragm ST, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8 and a filter G1.

the third lens element L3 is a plastic aspheric lens element with positive refractive power, the object-side surface S5 of the third lens element is convex, and the image-side surface S6 of the third lens element is convex at the paraxial region;

the fourth lens element L4 is a plastic aspheric lens with negative power, the object-side surface S7 of the fourth lens element is concave, and the image-side surface S8 of the fourth lens element is convex;

the eighth lens element L8 is a plastic aspheric lens element with negative power, the object-side surface S15 of the eighth lens element is concave, and the image-side surface S16 of the eighth lens element is concave at the paraxial region;

The relevant parameters of each lens in the optical lens 400 in the present embodiment are shown in table 7.

TABLE 7

The surface shape coefficients of the aspherical surfaces of the optical lens 400 in the present embodiment are shown in table 8.

TABLE 8

In the present embodiment, the graphs of field curvature, distortion, on-axis spherical aberration and lateral chromatic aberration of the optical lens 400 are respectively shown in fig. 17, fig. 18, fig. 19 and fig. 20, and it can be seen from fig. 17 to fig. 20 that the field curvature is controlled within ± 0.05mm, the optical distortion is controlled within ± 2%, the axial chromatic aberration of the shortest wavelength and the largest wavelength is controlled within ± 0.03mm, and the chromatic aberration of each wavelength with respect to the central wavelength in different fields of view is controlled within ± 2 microns, which indicates that the field curvature, distortion and chromatic aberration of the optical lens 400 are well corrected.

Fifth embodiment

Referring to fig. 21, a schematic structural diagram of an optical lens 500 provided in this embodiment includes, from an object side to an image plane S19 along an optical axis, the optical lens 500: the stop ST, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, and the filter G1.

The relevant parameters of each lens in the optical lens 500 in the present embodiment are shown in table 9.

TABLE 9

The surface shape coefficients of the aspherical surfaces of the optical lens 500 in the present embodiment are shown in table 10.

Watch 10

In the present embodiment, the graphs of field curvature, distortion, on-axis spherical aberration and lateral chromatic aberration of the optical lens 500 are respectively shown in fig. 22, fig. 23, fig. 24 and fig. 25, and it can be seen from fig. 22 to fig. 25 that the field curvature is controlled within ± 0.2mm, the optical distortion is controlled within ± 2%, the axial chromatic aberration of the shortest wavelength and the largest wavelength is controlled within ± 0.02mm, and the chromatic aberration of each wavelength with respect to the central wavelength in different fields of view is controlled within ± 2 microns, which indicates that the field curvature, distortion and chromatic aberration of the optical lens 500 are well corrected.

Table 11 shows the optical characteristics corresponding to the above five embodiments, which mainly includes the effective focal length F of the optical lens, the actual half-image height IH, the F #, the total optical length TTL, and the maximum field angle 2 θ, the effective focal length F1 of the first lens, the effective focal length F2 of the second lens, the effective focal length F3 of the third lens, the effective focal length F4 of the fourth lens, the effective focal length F5 of the fifth lens, the effective focal length F6 of the sixth lens, the effective focal length F7 of the seventh lens, the effective focal length F8 of the eighth lens, and the values corresponding to each conditional expression.

TABLE 11

In summary, the optical lens provided by the embodiments of the present invention has at least the following advantages:

(1) the optical lens provided by the invention adopts eight aspheric lenses, and adopts specific surface shape collocation and reasonable focal power distribution, so that the optical lens has the advantages of large aperture, high pixel and compact structure.

(2) The optical lens provided by the invention can be matched with a large-size sensor chip, so that the photosensitive area of the optical lens is increased, and the optical lens can image more clearly when working in a dark environment or under sufficient light.

The optical lens in the above embodiments can be applied to mobile phones, tablets, cameras, and other terminals.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. An optical lens system comprising eight lens elements, in order from an object side to an image plane along an optical axis:

a diaphragm;

a first lens having a positive optical power, the first lens having a convex object-side surface and a concave image-side surface at a paraxial region;

the second lens with negative focal power is characterized in that the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;

a third lens having a positive optical power, an object side surface of the third lens being convex;

a fourth lens having an optical power;

the lens system comprises a fifth lens with focal power, a second lens and a third lens, wherein the object-side surface of the fifth lens is a concave surface, and the image-side surface of the fifth lens is a convex surface;

a sixth lens having a optical power, an object-side surface of the sixth lens being convex at a paraxial region, an image-side surface of the sixth lens being concave at a paraxial region;

a seventh lens having a power, an object side surface of the seventh lens being convex at a paraxial region, an image side surface of the seventh lens being concave at a paraxial region;

an eighth lens having a negative optical power, an object side surface of the eighth lens being a concave surface;

the optical lens satisfies the following conditional expression:

0.16<(SAG61+SAG71)/(SAG62+SAG72)<0.48；

wherein SAG61 represents the saggital height of the object-side surface of the sixth lens, SAG71 represents the saggital height of the object-side surface of the seventh lens, SAG62 represents the saggital height of the image-side surface of the sixth lens, and SAG72 represents the saggital height of the image-side surface of the seventh lens.

2. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression:

6mm<IH<7mm；

1.6<f/EPD<2.0；

wherein IH represents an actual half-image height of the optical lens, f represents an effective focal length of the optical lens, and EPD represents an entrance pupil diameter of the optical lens.

3. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression:

6.12 mm<f*tanθ<6.14 mm；

where f denotes an effective focal length of the optical lens, and θ denotes a maximum half field angle of the optical lens.

4. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression:

2.195<DM82/DM12<2.69；

wherein DM82 represents the maximum effective diameter of the image-side surface of the eighth lens, and DM12 represents the maximum effective diameter of the image-side surface of the first lens.

5. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression:

9.75<TTL/BFL<14.66；

wherein, TTL represents the optical total length of the optical lens, and BFL represents the optical back focus of the optical lens.

6. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression:

1.07< CT34/(CT3+CT4)<1.21；

wherein CT34 denotes a distance on an optical axis from an image-side surface of the third lens to an object-side surface of the fourth lens, CT3 denotes a center thickness of the third lens, and CT4 denotes a center thickness of the fourth lens.

7. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression:

-0.71< (SAG41+SAG42)/ET4<1.24；

-2.43<SAG61/CT6<-0.335；

wherein SAG41 represents the sagged height of the object side of the fourth lens, SAG42 represents the sagged height of the image side of the fourth lens, ET4 represents the edge thickness of the fourth lens, SAG61 represents the sagged height of the object side of the sixth lens, and CT6 represents the center thickness of the sixth lens.

8. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression:

1.72 mm<DT11/tanθ<2.17 mm；

where DT11 denotes a maximum effective half diameter of an object-side surface of the first lens, and θ denotes a maximum half field angle of the optical lens.

9. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression:

1.36<(R21+R22)/f<3.96；

wherein R21 denotes a radius of curvature of an object side surface of the second lens, R22 denotes a radius of curvature of an image side surface of the second lens, and f denotes an effective focal length of the optical lens.

10. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression:

0.97<(CT2+CT3+CT4+CT5)/(ET2+ET3+ET4+ET5)<1.35；

wherein CT2 denotes a center thickness of the second lens, CT3 denotes a center thickness of the third lens, CT4 denotes a center thickness of the fourth lens, CT5 denotes a center thickness of the fifth lens, ET2 denotes an edge thickness of the second lens, ET3 denotes an edge thickness of the third lens, ET4 denotes an edge thickness of the fourth lens, and ET5 denotes an edge thickness of the fifth lens.

11. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression:

-17.67 mm<(Nd3*f2)/Nd1<-8.94 mm；

where Nd3 denotes a refractive index of the third lens, f2 denotes an effective focal length of the second lens, and Nd1 denotes a refractive index of the first lens.

12. The optical lens assembly as claimed in claim 1, wherein the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element, the sixth lens element, the seventh lens element and the eighth lens element are all plastic aspheric lens elements.