CN114578530A

CN114578530A - Optical lens

Info

Publication number: CN114578530A
Application number: CN202210483673.1A
Authority: CN
Inventors: 章彬炜; 徐文; 曾昊杰
Original assignee: Jiangxi Lianyi Optics Co Ltd
Current assignee: Jiangxi Lianyi Optics Co Ltd
Priority date: 2022-05-06
Filing date: 2022-05-06
Publication date: 2022-06-03
Anticipated expiration: 2042-05-06
Also published as: CN114578530B

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; 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 an optical power; the image side surface of the fifth lens is a convex surface; a sixth lens having a negative optical power; 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; an eighth lens element having a negative power and an object-side surface that is convex at a paraxial region and an image-side surface that is concave at a paraxial region. The optical lens has the advantages of large aperture, high pixel and compact structure, and can be matched with a large-size sensor chip to realize high-definition imaging.

Description

Optical lens

Technical Field

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

Background

With the rapid upgrade of portable electronic devices, consumers have an increasing demand for a photographing function, and pursue higher pixels. Since 2018, after related mobile phone manufacturers start using 40M high-pixel lenses with large-size sensor chips of 1/1.7 inches, all portable electronic device manufacturers successively release devices with high-pixel lenses with large-size sensor chips, and nowadays, the high-pixel lenses with large-size sensor chips have become the standard for flagship machines of all portable electronic device manufacturers.

In order to ensure the promotion of pixels, the size of pixel points of the sensor chip is not reduced, so that the increase of the size of the sensor chip becomes an important development trend of high pixels. Therefore, how to develop a small-sized high-pixel optical lens with a large-sized sensor chip is a technical problem to be solved by those skilled in the art.

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 matched 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 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, 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 image side surface of the fifth lens is a convex surface; a sixth lens having a negative optical power; a seventh lens having a light 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 convex at a paraxial region and an image-side surface of the eighth lens being concave at a paraxial region; wherein, the optical lens satisfies the following conditional expression: 1< f4/f7< 40; wherein f4 denotes a focal length of the fourth lens, and f7 denotes a focal length of the seventh lens.

Compared with the prior art, the optical lens provided by the invention adopts an eight-piece compact structure, and through reasonable matching of the focal power and the surface type of each lens, the lens has a larger imaging surface, can be matched with a 1/1.31-inch large-size sensor chip, and meets the current mainstream shooting configuration; meanwhile, the optical lens has the characteristic of a large aperture, and the light incoming quantity is more, so that the optical lens has high-definition imaging quality even in a dark environment or under strong light; and the optical lens also has 50M ultrahigh pixels, and can output a 108M pixel level photo at the highest by matching with later-stage algorithm optimization, thereby reaching the top level in the market and having stronger market competitiveness.

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 diagram 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 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 of 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.

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 presented 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.

The first lens has positive optical focus, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface at a position close to an optical axis;

the second lens has negative focal power, 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 focal power;

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

the sixth lens has negative focal power;

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

the eighth lens element has a negative optical power, and an object-side surface of the eighth lens element is convex at a paraxial region and an image-side surface of the eighth lens element is concave at a paraxial region.

Wherein, the optical lens satisfies the following conditional expression:

1<f4/f7<40；（1）

where f4 denotes a focal length of the fourth lens, and f7 denotes a focal length of the seventh lens. The optical lens meets the condition formula (1), and the total length of the optical lens is favorably shortened by reasonably distributing the focal power of the fourth lens and the seventh lens, so that the ultra-thinning development trend of the portable electronic equipment is met.

In some embodiments, the fourth lens has a positive optical power and the seventh lens has a positive optical power; the third lens element has a concave image-side surface at the paraxial region, the fourth lens element has a convex image-side surface at the paraxial region, the fifth lens element has a convex object-side surface at the paraxial region, the sixth lens element has a convex object-side surface at the paraxial region, and the sixth lens element has a concave image-side surface at the paraxial region.

In some embodiments, the fourth lens has a negative optical power and the seventh lens has a negative optical power; the image-side surface of the third lens element is convex at a paraxial region, the image-side surface of the fourth lens element is concave at a paraxial region, the object-side surface of the fifth lens element is concave, the object-side surface of the sixth lens element is concave, and the image-side surface of the sixth lens element is convex. The lenses in the optical lens are matched and combined in different surface types, so that the system can achieve a good imaging effect.

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

-3<f2/f<-0.5；（2）

0.3<(R21+R22)/(R21-R22)<2；（3）

where f denotes an effective focal length of the optical lens, f2 denotes a focal length of the second lens, R21 denotes a radius of curvature of an object-side surface of the second lens, and R22 denotes a radius of curvature of an image-side surface of the second lens. Satisfy above-mentioned conditional expression (2), (3), through the negative power and the face type that set up the second lens rationally, can slow down the trend of light deflection better, be favorable to reducing the sensitivity of second lens, reduce the forming process degree of difficulty of second lens.

2<f3/f<3；（4）

-3<(R31+R32)/(R31-R32)<0；（5）

where f denotes an effective focal length of the optical lens, f3 denotes a focal length of the third lens, R31 denotes a radius of curvature of an object-side surface of the third lens, and R32 denotes a radius of curvature of an image-side surface of the third lens. The optical focal power and the surface type of the third lens are reasonably set to ensure that the third lens bears reasonable positive focal power in the optical lens, so that the trend of light deflection can be accelerated, the aperture of the optical lens is favorably reduced, and the miniaturization of the lens is realized.

0.1<f5/f<7；（6）

-1<(R51+R52)/(R51-R52)<5；（7）

where f denotes an effective focal length of the optical lens, f5 denotes a focal length of the fifth lens, R51 denotes a radius of curvature of an object-side surface of the fifth lens, and R52 denotes a radius of curvature of an image-side surface of the fifth lens. And the conditional expressions (6) and (7) are met, so that the fifth lens bears reasonable positive focal power in the optical lens to adjust the aberration of peripheral light, the imaging quality of the optical lens is improved, and ultrahigh pixel imaging of the lens is realized.

-11<f6/f<-1；（8）

0<R61/R62<3；（9）

where f denotes an effective focal length of the optical lens, f6 denotes a focal length of the sixth lens, R61 denotes a radius of curvature of an object-side surface of the sixth lens, and R62 denotes a radius of curvature of an image-side surface of the sixth lens. The conditional expressions (8) and (9) are met, so that the sixth lens bears a certain negative focal power, the focusing efficiency of light on the image surface is reduced, the correction of peripheral field coma is facilitated, the illumination of the peripheral field is effectively improved, and the overall imaging quality is improved.

-1.4<f8/f<-0.1；（10）

1<(R81+R82)/(R81-R82)<2；（11）

where f denotes an effective focal length of the optical lens, f8 denotes a focal length of the eighth lens, R81 denotes a radius of curvature of an object-side surface of the eighth lens, and R82 denotes a radius of curvature of an image-side surface of the eighth lens. The optical power and the surface type of the eighth lens are reasonably set, so that the optical power and the surface type of the eighth lens are favorably reduced, the light deflection tendency is favorably slowed down, the imaging of the light at an overlarge angle of an image plane is avoided, the correction difficulty of the chromatic aberration and the spherical aberration of the lens is reduced, and the integral imaging quality is improved.

6.0mm<IH<7.0mm；（12）

1.3<TTL/IH<1.6；（13）

wherein IH represents a half of an image height corresponding to a maximum field angle of the optical lens, and TTL represents an optical total length of the optical lens. Satisfying the conditional expressions (12) and (13) can achieve a better balance between a small volume and a high pixel of the optical lens.

1.6<f/EPD<2.0；（14）

where f represents an effective focal length of the optical lens, and EPD represents an entrance pupil diameter of the optical lens. The conditional expression (14) is satisfied, the light flux of the optical lens is favorably improved, the optical lens can normally shoot in a dark environment or under strong light, and the effect of blurring the main body prominent background can be achieved in normal illumination shooting.

0.3<(SAG11-SAG12)/CT1<0.9；（15）

where SAG11 denotes the sagittal height of the object side surface of the first lens (sagittal height denotes the distance between the point on the lens surface perpendicular to the optical axis at the effective aperture and the central vertex of the lens surface), SAG12 denotes the sagittal height of the image side surface of the first lens, and CT1 denotes the central thickness of the first lens. The shape of the first lens can be reasonably controlled by satisfying the conditional expression (15), so that the object side surface of the first lens has no recurvation, the resolution of the optical lens is improved, and the sensitivity of the whole optical system is reduced.

0.04<ET2/TTL< 0.055；（16）

wherein ET2 denotes an edge thickness of the second lens, and TTL denotes an optical total length of the optical lens. The condition formula (16) is satisfied, the edge thickness of the second lens can be effectively controlled, the optical lens is prevented from being broken due to the fact that the edge thickness of the second lens is too thin in the assembling process, and the yield in the production process is guaranteed.

1.5<f34/f <5；（17）

where f34 denotes a combined focal length of the third lens and the fourth lens, and f denotes an effective focal length of the optical 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 (17) is met, so that the trend of light deflection is accelerated, and the compactness and the miniaturization of the optical lens structure are realized.

0.04<AC56/TTL<0.09；（18）

where AC56 denotes an air space on the optical axis between the fifth lens and the sixth lens, and TTL denotes the total optical length of the optical lens. The distance between the fifth lens and the sixth lens can be reasonably controlled by satisfying the conditional expression (18), and the tendency of light ray deflection is favorably relieved, so that the sensitivity of the whole optical system is reduced, and the difficulty of assembling and producing the optical lens is reduced.

1.1<DM8/DM6<2；（19）

where DM8 denotes the effective aperture of the eighth lens, and DM6 denotes the effective aperture of the sixth lens. The condition formula (19) is satisfied, the projection height of light on the image plane is favorably raised, the optical lens has a larger image plane, the high pixel of the optical lens is better realized, and meanwhile, the light deflection is avoided from being too fast.

0.06<BFL/TTL <0.09；（20）

wherein BFL represents the optical back focus of the optical lens, and TTL represents the optical total length of the optical lens. The optical back focus of the optical lens can be reasonably controlled when the conditional expression (20) is met, so that the interference phenomenon between the lens and the large-size sensor chip is reduced, and the phenomenon that the imaging of the optical lens at the close-range photographing edge is fuzzy due to the matching of the large-size sensor chip is reduced.

As an implementation manner, eight lenses in the optical lens can adopt full plastic lenses, and can also adopt glass-plastic mixed matching, so that a good imaging effect can be obtained; in the invention, in order to better reduce the volume of the lens and reduce the cost, eight plastic lenses are combined, and the optical lens has a more compact structure and ultra-high pixels through specific surface shape collocation and reasonable focal power distribution, and can be matched with a 1/1.31-inch large-size sensor chip to realize ultra-high definition imaging. The first lens to the eighth lens are plastic aspheric lenses, and aspheric lenses are adopted, so that cost can be effectively reduced, aberration can be corrected, and a product with higher performance-price ratio can be provided.

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 only by the following examples, and any other changes, substitutions, combinations or simplifications which do not depart from the innovative points of the present invention should be construed as being equivalent substitutions and shall be included within the scope of the present invention.

The surface shape of the aspheric lens in each embodiment of the invention satisfies the following equation:

wherein z is the distance rise from the aspheric surface vertex when the aspheric surface is at the position with the height h along the optical axis direction, c is the paraxial curvature of the surface, k is the quadric coefficient, A_2iIs the aspheric surface type coefficient of 2i order.

In the following embodiments, the thickness, the curvature radius, and the material selection of each lens in the optical lens are different, and specific differences can be referred to in the parameter tables of the embodiments.

First embodiment

Referring to fig. 1, a schematic structural diagram of an optical lens 100 according to a first embodiment of the present invention includes, in order 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 L1 has positive power, the object-side surface S1 of the first lens is convex, and the image-side surface S2 of the first lens is concave at the paraxial region;

the second lens element L2 has a negative power, the object side surface S3 of the second lens element is concave at the paraxial region, and the image side surface S4 of the second lens element is concave;

the third lens L3 has positive focal power, the object-side surface S5 of the third lens is convex, and the image-side surface S6 of the third lens is concave;

the fourth lens L4 has positive focal power, the object-side surface S7 of the fourth lens is concave, and the image-side surface S8 of the fourth lens is convex;

the fifth lens element L5 has positive optical power, the fifth lens element has an object-side surface S9 that is convex at the paraxial region, and has an image-side surface S10 that is convex;

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

the seventh lens element L7 has positive optical power, with an object-side surface S13 of the seventh lens element being convex at the paraxial region and an image-side surface S14 of the seventh lens element being concave at the paraxial region;

the eighth lens element L8 has a negative power, with its object-side surface S15 being convex at the paraxial region and its image-side surface S16 being concave at the paraxial region.

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

In the present embodiment, the eight lenses in the optical lens 100 are all plastic aspheric lenses.

The parameters related to each lens in the optical lens 100 provided in the present embodiment are shown in table 1.

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 ± 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 ± 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, the structural schematic diagram of the optical lens 200 provided in the present embodiment shows that the structural changes of the optical lens 200 in the present embodiment and the optical lens 100 in the first embodiment are large, specifically, the focal power and the surface type of each lens in the optical lens 200 are as follows:

the second lens element L2 has negative power, the object-side surface S3 of the second lens element is convex at the paraxial region, and the image-side surface S4 of the second lens element is concave;

the third lens L3 has positive focal power, the object-side surface S5 of the third lens is convex, and the image-side surface S6 of the third lens is convex;

the fourth lens element L4 has a 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 concave at the paraxial region;

the fifth lens L5 has positive focal power, the object-side surface S9 of the fifth lens is a concave surface, and the image-side surface S10 of the fifth lens is a convex surface;

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

the seventh lens element L7 has a negative power, the object-side surface S13 of the seventh lens element being convex at the paraxial region, and the image-side surface S14 of the seventh lens element being 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 ± 1mm, the optical distortion is controlled within ± 2.5%, the axial chromatic aberration of the shortest wavelength and the largest wavelength is controlled within ± 0.06mm, and the chromatic aberration of each wavelength relative to the central wavelength in different fields of view is controlled within ± 1.5 microns, which indicates that the field curvature, distortion and chromatic aberration of the optical lens 200 are all well corrected.

Third embodiment

Referring to fig. 11, a schematic structural diagram of an optical lens 300 in the present embodiment is shown, where the structure of the optical lens 300 in the present embodiment is substantially the same as that of the optical lens 200 in the second embodiment, except that an object-side surface S7 of the fourth lens element is convex at a paraxial region, and parameters such as a curvature radius and a thickness of each lens element are different.

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 ± 0.3mm, the optical distortion is controlled within ± 2%, the axial chromatic aberration of the shortest wavelength and the largest wavelength is controlled within ± 0.08mm, 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 the present embodiment is similar to the optical lens 200 in the second embodiment in structure, except that an object-side surface S3 of the second lens element is concave at a paraxial region, an object-side surface S7 of the fourth lens element is convex at a paraxial region, and parameters such as a curvature radius and a thickness of each lens element are different.

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 shown in fig. 17, fig. 18, fig. 19 and fig. 20, respectively, 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 ± 1.2 microns, which indicates that the field curvature, distortion and chromatic aberration of the optical lens 400 are well corrected.

Table 9 shows the optical characteristics corresponding to the above four embodiments, which mainly include the effective focal length F, F # of the optical lens, total optical length TTL, half IH of the image height corresponding to the maximum field angle and the maximum field angle 2 θ, and the values corresponding to each of the above conditional expressions.

TABLE 9

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

(1) the optical lens provided by the invention adopts an eight-piece compact structure, and adopts specific surface shape collocation and reasonable focal power distribution, so that the optical lens has the advantages of 50M ultrahigh pixels, compact structure and the like;

(2) the optical lens provided by the invention has a larger imaging surface by reasonably matching the focal power and the surface type of each lens, can be matched with a large-size sensor chip of 1/1.31 inch, and meets the current mainstream shooting configuration;

(3) the optical lens provided by the invention has a larger aperture, the control range of the light transmission amount is larger, and the shooting in a dim light or dark environment is facilitated; the field depth range is set to be larger, and an imaging picture has stronger depth feeling and space feeling.

In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means 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 examples are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. An optical lens, comprising, 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, 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 image side surface of the fifth lens is a convex surface;

a sixth lens having a negative optical power;

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 convex at a paraxial region and an image-side surface of the eighth lens being concave at a paraxial region;

wherein, the optical lens satisfies the following conditional expression:

1<f4/f7<40；

wherein f4 denotes a focal length of the fourth lens, and f7 denotes a focal length of the seventh lens.

2. An optical lens according to claim 1, characterized in that the fourth lens has a positive optical power and the seventh lens has a positive optical power; the image-side surface of the third lens element is concave at the paraxial region, the image-side surface of the fourth lens element is convex at the paraxial region, the object-side surface of the fifth lens element is convex at the paraxial region, the object-side surface of the sixth lens element is convex at the paraxial region, and the image-side surface of the sixth lens element is concave at the paraxial region.

3. An optical lens according to claim 1, characterized in that the fourth lens has a negative optical power and the seventh lens has a negative optical power; the image side surface of the third lens element is convex at the paraxial region, the image side surface of the fourth lens element is concave at the paraxial region, the object side surface of the fifth lens element is concave, the object side surface of the sixth lens element is concave, and the image side surface of the sixth lens element is convex.

4. An optical lens according to any one of claims 1 to 3, characterized in that the optical lens satisfies the following conditional expression:

-3<f2/f<-0.5；

0.3<(R21+R22)/(R21-R22)<2；

where f denotes an effective focal length of the optical lens, f2 denotes a focal length of the second lens, R21 denotes a radius of curvature of an object side surface of the second lens, and R22 denotes a radius of curvature of an image side surface of the second lens.

5. An optical lens according to any one of claims 1 to 3, characterized in that the optical lens satisfies the following conditional expression:

2<f3/f<3；

-3<(R31+R32)/(R31-R32)<0；

where f denotes an effective focal length of the optical lens, f3 denotes a focal length of the third lens, R31 denotes a radius of curvature of an object-side surface of the third lens, and R32 denotes a radius of curvature of an image-side surface of the third lens.

6. An optical lens according to any one of claims 1 to 3, characterized in that the optical lens satisfies the following conditional expression:

0.1<f5/f<7；

-1<(R51+R52)/(R51-R52)<5；

where f denotes an effective focal length of the optical lens, f5 denotes a focal length of the fifth lens, R51 denotes a radius of curvature of an object-side surface of the fifth lens, and R52 denotes a radius of curvature of an image-side surface of the fifth lens.

7. An optical lens according to any one of claims 1 to 3, characterized in that the optical lens satisfies the following conditional expression:

-11<f6/f<-1；

0<R61/R62<3；

where f denotes an effective focal length of the optical lens, f6 denotes a focal length of the sixth lens, R61 denotes a radius of curvature of an object-side surface of the sixth lens, and R62 denotes a radius of curvature of an image-side surface of the sixth lens.

8. An optical lens according to any one of claims 1 to 3, characterized in that the optical lens satisfies the following conditional expression:

-1.4<f8/f<-0.1；

1<(R81+R82)/(R81-R82)<2；

where f denotes an effective focal length of the optical lens, f8 denotes a focal length of the eighth lens, R81 denotes a radius of curvature of an object-side surface of the eighth lens, and R82 denotes a radius of curvature of an image-side surface of the eighth lens.

9. An optical lens according to any one of claims 1 to 3, characterized in that the optical lens satisfies the following conditional expression:

1.3<TTL/IH<1.6；

wherein IH represents a half of an image height corresponding to a maximum field angle of the optical lens, and TTL represents an optical total length of the optical lens.

10. An optical lens according to any one of claims 1 to 3, characterized in that the optical lens satisfies the following conditional expression:

1.6<f/EPD<2.0；

where f represents an effective focal length of the optical lens, and EPD represents an entrance pupil diameter of the optical lens.

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

1.5<f34/f < 5；

wherein f34 represents a combined focal length of the third lens and the fourth lens, and f represents an effective focal length of the optical lens.