CN115390225B

CN115390225B - Optical lens

Info

Publication number: CN115390225B
Application number: CN202211333612.3A
Authority: CN
Inventors: 章彬炜; 匡博洋; 曾昊杰
Original assignee: Jiangxi Lianyi Optics Co Ltd
Current assignee: Jiangxi Lianyi Optics Co Ltd
Priority date: 2022-10-28
Filing date: 2022-10-28
Publication date: 2023-03-24
Anticipated expiration: 2042-10-28
Also published as: CN115390225A

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; the first lens with positive focal power, its object side is a convex surface, the image side is a concave surface; a second lens element having a negative optical power, the object-side surface of which is convex at the paraxial region and the image-side surface of which is concave; a third lens with negative focal power, wherein the image side surface of the third lens is a concave surface; a fourth lens element having positive optical power, the object-side surface of the fourth lens element being convex and the image-side surface of the fourth lens element being concave at the paraxial region; a fifth lens element with positive optical power having a convex object-side surface and a convex image-side surface at paraxial region; a sixth lens element with negative refractive power having a concave object-side surface and a convex image-side surface; a seventh lens having a negative refractive power, an object side surface of which is concave; the effective focal length f of the optical lens and the image height IH corresponding to the maximum half field angle satisfy the conditional expression: 1.5 and < -f/IH <1.8. The invention can satisfy the balance of large aperture, high pixel and long focal length by reasonably restricting the surface type and focal power of each lens.

Description

Optical lens

Technical Field

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

Background

With the rapid growth of consumer electronics market and the popularity of social, video and live broadcast software, people have higher and higher requirements for the imaging quality of the camera lens, and the camera lens even becomes an index of primary consideration when consumers purchase electronic equipment.

Particularly, with the increasing liveness of people on social networking platforms, higher requirements are put forward on the optical performance of electronic shooting equipment, particularly on the aspect of portrait shooting, the imaging lens is required to be capable of clearly shooting in a dark environment and also capable of clearly imaging in a far environment, and the characteristics of long focal length and small depth of field are required to better realize the functions of blurring a background and highlighting a main body, so that more textured portrait photos are shot. At present, in many imaging lenses, the image quality is blurred in environments with poor light conditions, such as night scene shooting or indoor shooting. In addition, most lenses can image a subject well when shooting a close shot, but have poor imaging of a distant target and cannot give consideration to high-pixel distant imaging, and when shooting a distant subject, the problem that the subject cannot be highlighted occurs.

Accordingly, there is a need to develop an optical lens with a large aperture, a long focal length and a small depth of field to meet the shooting requirements of electronic devices.

Disclosure of Invention

Therefore, an object of the present invention is to provide an optical lens having at least advantages of large aperture, long focal length, and high pixel.

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;

the lens comprises a first lens with positive focal power, a second lens and a third lens, wherein 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;

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

a third lens with negative focal power, wherein the image side surface of the third lens is a concave surface;

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

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

the lens comprises a sixth lens with negative focal power, wherein the object side surface of the sixth lens is a concave surface, and the image side surface of the sixth lens is a convex surface;

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

the optical lens satisfies the following conditional expression:

1.5<f/IH<1.8；

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

Compared with the prior art, the optical lens provided by the invention adopts seven lenses with specific focal power, and adopts specific surface shape collocation and reasonable focal power distribution, so that the optical lens has the characteristics of high pixel and long focal length, can better realize background blurring and highlight the function of a main body; the size of the aperture of the lens is reasonably controlled, so that the light inlet quantity of the system can be effectively enlarged, and the lens can achieve a good shooting effect in a dark environment.

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 graph showing F-Tan (θ) distortion of the optical lens according to the first embodiment of the present invention;

FIG. 4 is a vertical axis chromatic aberration diagram of an optical lens according to a first embodiment of the present invention;

FIG. 5 is a schematic structural diagram of an optical lens system according to a second embodiment of the present invention;

FIG. 6 is a field curvature graph of an optical lens according to a second embodiment of the present invention;

fig. 7 is a graph showing F-Tan (θ) distortion of an optical lens according to a second embodiment of the present invention;

FIG. 8 is a vertical axis chromatic aberration diagram of an optical lens according to a second embodiment of the present invention;

FIG. 9 is a schematic structural diagram of an optical lens assembly according to a third embodiment of the present invention;

FIG. 10 is a field curvature graph of an optical lens according to a third embodiment of the present invention;

fig. 11 is a graph showing F-Tan (θ) distortion of an optical lens according to a third embodiment of the present invention;

fig. 12 is a vertical axis chromatic aberration diagram of an optical lens according to a third 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 and an optical filter.

The first lens has positive focal power, 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;

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

the third lens has negative focal power, and the image side surface of the third lens is a concave surface;

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

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

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

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

In the above lenses, the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element, the sixth lens element and the seventh lens element are all plastic aspheric lens elements. The invention reasonably restricts the surface type and focal power of each lens to ensure that the lens meets the balance of large aperture, small total length and long focal length.

In an embodiment of the present invention, the optical lens satisfies the following conditional expression:

1.5<f/IH<1.8；（1）

wherein f represents an effective focal length of the optical lens, and IH represents an image height corresponding to a maximum half field angle of the optical lens. The camera lens can be controlled to have a longer focal length by satisfying the conditional expression (1), and the main body can be well shot in a protruding mode when shooting is guaranteed, the background is blurred, and portrait shooting is better carried out.

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

-0.5<f1/f2<0；（2）

wherein f1 represents an effective focal length of the first lens, and f2 represents an effective focal length of the second lens. The condition formula (2) is met, the long focal length and the high pixel balance of the optical lens are favorably realized by reasonably distributing the focal lengths of the first lens and the second lens, and the total length of the optical lens is favorably shortened.

0.5<f1/f<1.1；（3）

wherein f1 represents an effective focal length of the first lens. The condition (3) is satisfied, and the primary spherical aberration of the system can be effectively corrected by reasonably setting the focal length of the first lens, so that the machinability of the first lens is improved, and the yield is improved.

-0.4<f/f2<0；（4）

where f2 denotes an effective focal length of the second lens. The positive focal power contribution rate of the second lens can be reasonably controlled by satisfying the conditional expression (4), and the deflection angle of marginal light rays can be favorably controlled, so that the light rays are uniformly deflected when passing through each lens, the spherical aberration of a system is better corrected, and the integral imaging quality is improved.

-4<f3/f<-0.8；（5）

wherein f3 represents an effective focal length of the third lens. The condition formula (5) is met, the negative refractive power of the third lens is reasonably set, the focal power change in the lens group can be balanced, the aberration correction difficulty is reduced, and the imaging quality of the lens is improved.

0.4<f/f4<0.7；（6）

wherein f4 represents an effective focal length of the fourth lens. And the fourth lens has proper positive focal power when the conditional expression (6) is met, so that the convergence of light rays is facilitated, divergent light rays entering the system from the front smoothly enter the rear optical system, the whole light path trend is smoother, the aberration is optimized, and the resolution is improved.

0.8<f5/f<8；（7）

wherein f5 denotes an effective focal length of the fifth lens. Satisfy conditional expression (7), through the focus of reasonable setting fifth lens, the aberration that the preceding lens group of correction that can be better brought improves senior spherical aberration, coma, is favorable to realizing the uniformity of high resolution and whole resolution.

1<f4/f5<4；（8）

where f4 denotes an effective focal length of the fourth lens, and f5 denotes an effective focal length of the fifth lens. The conditional expression (8) is satisfied, the focal length ratio of the fourth lens and the fifth lens is reasonably controlled, coma aberration correction of an off-axis field of view is facilitated to be enhanced, and meanwhile, the field curvature and the aberration are well converged, so that the lens has higher resolving power.

-50<f6/f<-1；（9）

where f6 denotes an effective focal length of the sixth lens. And the conditional expression (9) is satisfied, and the focal length of the sixth lens is reasonably set, so that the optical distortion and the aberration are favorably corrected, and the imaging quality of the optical lens is improved.

-1<f7/f<-0.5；（10）

wherein f7 denotes an effective focal length of the seventh lens. The seventh lens has proper negative focal power when the conditional expression (10) is satisfied, so that the imaging area of the lens can be increased, the aberration of the front lens is balanced, and the integral imaging quality of the lens is improved.

1.5<f/EPD<1.8；（11）

wherein EPD represents an entrance pupil diameter of the optical lens. Satisfying conditional expression (11), the light volume of advancing of system can rationally be increased, the big light ring characteristic of system is realized, especially when optical lens is formation of image in dark environment, can reduce the noise influence that light is too weak and bring to improve the imaging quality, make this optical lens can satisfy the formation of image demand under the different luminous flux condition.

-5<R61/f<-0.5；（12）

0.1<R61/R62<1；（13）

wherein R61 denotes a radius of curvature of an object-side surface of the sixth lens element, and R62 denotes a radius of curvature of an image-side surface of the sixth lens element. The surface type of the sixth negative lens is reasonably set to correct off-axis aberration and enable light rays to have proper incident and emergent angles in the sixth lens, so that the angle of field and the area of an imaging surface are increased.

2.3<CT2/CT3 <4.5；（14）

1<DM2/DM3<1.2；（15）

wherein CT2 represents a center thickness of the second lens, CT3 represents a center thickness of the third lens, DM2 represents an effective aperture of the second lens, and DM3 represents an effective aperture of the third lens. The optical lens meets the conditional expressions (14) and (15), and the turning trend of light can be effectively slowed down by reasonably controlling the medium thickness and the caliber ratio of the second lens and the third lens, so that the optical lens is favorable for correcting the aberration and distortion of an off-axis field of view, and ensures high-quality imaging of the optical lens.

DM4/DMi <1, i =1, 2, 3, 5, 6, or 7; (16)

Wherein DM1 represents an effective aperture of the first lens, DM2 represents an effective aperture of the second lens, DM3 represents an effective aperture of the third lens, DM4 represents an effective aperture of the fourth lens, DM5 represents an effective aperture of the fifth lens, DM6 represents an effective aperture of the sixth lens, DM7 represents an effective aperture of the seventh lens, and DMi represents an effective aperture of the ith lens. Satisfying above-mentioned conditional expression (16), can making the fourth lens at the bore minimum of all lenses, can effectively control the optical total length of this camera lens, can effectively slow down the turn degree of light simultaneously, can better control the aberration in each field of view, improve the camera lens image quality.

-1＜(R21+R22)/f2＜-0.2；（17）

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 f2 denotes an effective focal length of the second lens. Satisfying above-mentioned conditional expression (17), the face type of the second lens of can reasonable control helps reducing system sensitivity, promotes the manufacturing yield through reducing the shaping degree of difficulty, also can reduce the stray light that the camera lens produced simultaneously, promotes camera lens image quality.

-0.2<(SAG52-SAG51)/DM52<0；（18）

wherein SAG51 denotes a saggital height of an object-side surface of the fifth lens at the effective aperture, SAG52 denotes a saggital height of an image-side surface of the fifth lens at the effective aperture, and DM52 denotes an effective aperture of the image-side surface of the fifth lens. The conditional expression (18) is satisfied, and the rise and aperture relation of the fifth lens is reasonably set, so that the distribution of the light ray incidence angle can be effectively controlled, and the high-order aberration of the optical lens can be corrected.

0.05<(CT6+CT7)/TTL<0.35；（19）

1.2<CT6/CT7<2.0；(20)

wherein CT6 denotes a central thickness of the sixth lens on the optical axis, CT7 denotes a central thickness of the seventh lens on the optical axis, and TTL denotes a total optical length of the optical lens. Satisfy conditional expressions (19) and (20), through the central thickness of reasonable setting sixth lens and seventh lens to avoid the sixth lens too thin and cause the lens to mould the fat material and fill inequality when the shaping easily, or seventh lens thickness is too thick leads to the lens to cooperate interference and lens cone interference in the equipment process, influences the imaging effect.

1.3<SAG11/SAG12<2.3；（21）

wherein SAG11 represents the sagittal height of the object side surface of the first lens at the effective aperture, and SAG12 represents the sagittal height of the image side surface of the first lens at the effective aperture. The degree of curvature of the first lens can be reasonably controlled by satisfying the conditional expression (21), and the molding difficulty of the first lens can be reduced, so that the processing sensitivity is reduced, and the yield is improved.

As an implementation mode, the structure of the seven plastic aspheric lenses is adopted, and the surface type and focal power of each lens are reasonably restricted, so that the structure of the seven plastic aspheric lenses is compact, and the characteristics of large aperture, long focal length and small depth of field are realized. By adopting the aspheric lens, the cost can be effectively reduced, the aberration can be corrected, the imaging quality can be improved, and a product with higher performance-price ratio can be provided.

The invention is further illustrated below by means of a number of 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.

In the embodiments of the present invention, when the lenses in the optical lens are aspheric lenses, the aspheric surface types of the lenses all satisfy 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 _2i Is the aspheric surface type coefficient of 2i order.

First embodiment

Referring to fig. 1, a schematic structural diagram of an optical lens 100 according to a first embodiment of the present invention is shown, where the optical lens 100 sequentially includes, from an object side to an image plane 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, and the filter G1.

The first lens L1 has positive focal power, the object side surface S1 of the first lens is a convex surface, and the image side surface S2 of the first lens is a concave surface;

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

the third lens element L3 has a negative optical power, the object-side surface S5 of the third lens element is concave at the paraxial region, and the image-side surface S6 of the third lens element is concave;

the fourth lens element L4 has positive optical 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 at the paraxial region;

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

the sixth lens element L6 has negative refractive power, and the object-side surface S11 and the image-side surface S12 of the sixth lens element are concave and convex, respectively;

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

the object side surface of the filter G1 is S15, and the image side surface is S16.

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

Specifically, the design parameters of each lens of the optical lens 100 provided in this embodiment are shown in table 1.

TABLE 1

In this embodiment, aspheric parameters of each lens in the optical lens 100 are shown in table 2.

TABLE 2

In the present embodiment, graphs of field curvature, F-Tan (θ) distortion, and homeotropic chromatic aberration of the optical lens 100 are shown in fig. 2, 3, and 4, respectively.

The field curvature curve of fig. 2 indicates the degree of curvature of the meridional image plane and the sagittal image plane. In fig. 2, the horizontal axis represents the offset amount (unit: mm) and the vertical axis represents the angle of view (unit: degree). It can be seen from fig. 2 that the field curvature of the image plane in two directions is controlled within ± 0.05 mm, which indicates that the field curvature correction of the optical lens 100 is good.

The distortion curve of fig. 3 represents the F-Tan (θ) distortion at different image heights on the image plane. In fig. 3, the horizontal axis represents the distortion percentage, and the vertical axis represents the angle of view (unit: degree). It can be seen from the figure that the optical distortion is controlled within ± 2%, which indicates that the distortion of the optical lens 100 is well corrected.

The vertical axis chromatic aberration curve of fig. 4 indicates chromatic aberration at different image heights on the imaging plane for each wavelength with respect to the center wavelength (0.555 um). In fig. 4, the horizontal axis represents the homeotropic color difference (unit: μm) of each wavelength with respect to the center wavelength, and the vertical axis represents the normalized angle of view. As can be seen from fig. 4, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ± 1.2 microns, which indicates that the optical lens 100 can effectively correct the aberration of the fringe field and the secondary spectrum of the entire image plane.

As can be seen from fig. 2, 3, and 4, the aberrations of the optical lens 100 are well balanced, and the optical imaging quality is good.

Second embodiment

Referring to fig. 5, a schematic structural diagram of an optical lens 200 according to a second embodiment of the present invention is shown, where the optical lens 200 of the present embodiment is substantially the same as the first embodiment, and the difference is mainly that: the object side surface S5 of the third lens is a convex surface, and the curvature radius, the aspheric coefficient and the thickness of each lens surface type are different.

Specifically, the design parameters of the optical lens 200 provided in this embodiment are shown in table 3.

TABLE 3

In the present embodiment, aspheric parameters of the respective lenses in the optical lens 200 are shown in table 4.

TABLE 4

In the present embodiment, graphs of the field curvature curve, the F-Tan (θ) distortion, and the homeotropic chromatic aberration of the optical lens 200 are shown in fig. 6, 7, and 8, respectively.

As can be seen from fig. 6, the field curvature of the meridional image plane and the sagittal image plane is controlled within ± 0.15 mm, which indicates that the field curvature of the optical lens 200 is well corrected.

It can be seen from fig. 7 that the optical distortion is controlled within ± 2%, indicating that the distortion of the optical lens 200 is well corrected.

As can be seen from fig. 8, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ± 1.1 microns, which indicates that the optical lens 200 can effectively correct the aberration of the fringe field and the secondary spectrum of the entire image plane.

As can be seen from fig. 6, 7, and 8, the aberrations of the optical lens 200 are well balanced, and the optical imaging quality is good.

Third embodiment

Referring to fig. 9, a schematic structural diagram of an optical lens 300 according to a third embodiment of the present invention is shown, where the optical lens 300 of the present embodiment is substantially the same as the first embodiment, and the difference is mainly that: the image-side surface S14 of the seventh lens element is convex, and the curvature radius, aspheric coefficient, and thickness of each lens surface type are different.

Specifically, the design parameters of the optical lens 300 provided in this embodiment are shown in table 5.

TABLE 5

In the present embodiment, aspheric parameters of each lens in the optical lens 300 are shown in table 6.

TABLE 6

In the present embodiment, graphs of field curvature, F-Tan (θ) distortion, and homeotropic chromatic aberration of the optical lens 300 are shown in fig. 10, 11, and 12, respectively.

Fig. 10 shows that the field curvature of the meridional image plane and the sagittal image plane is controlled within ± 0.1 mm, which indicates that the field curvature correction of the optical lens 300 is good.

It can be seen from fig. 11 that the optical distortion is controlled within ± 1.50%, indicating that the distortion of the optical lens 300 is well corrected.

As can be seen from fig. 12, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ± 1.5 microns, which indicates that the optical lens 300 can effectively correct the aberration of the fringe field and the secondary spectrum of the entire image plane.

As can be seen from fig. 10, 11, and 12, the aberrations of the optical lens 300 are well balanced, and the optical imaging quality is good.

Please refer to table 7, which shows the optical characteristics corresponding to the optical lens provided in the above three embodiments, including the effective focal length f, the total optical length TTL, the maximum field angle 2 θ, the image height IH corresponding to the maximum half field angle, and the related values corresponding to each of the aforementioned conditional expressions.

TABLE 7

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

(1) The seven aspheric lenses with specific focal power are adopted, and the distortion, chromatic aberration and aberration of the lens can be well corrected through specific surface shape matching, so that the lens has high imaging quality.

(2) Because the focal power and the surface type of each lens are reasonably arranged, the optical lens has a longer focal length and a shorter depth of field, and can better realize the functions of blurring the background and highlighting the main body.

(3) The size of the aperture of the lens is reasonably controlled, so that the light inlet quantity of the system can be effectively enlarged, and the lens can achieve a good shooting effect in a dark environment.

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 more specific and detailed, but not construed as limiting the scope of the present 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 patent 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;

the optical lens satisfies the following conditional expression:

1.5<f/IH<1.8；

-4<f3/f<-0.8；

wherein f represents an effective focal length of the optical lens, IH represents an image height corresponding to a maximum half field angle of the optical lens, and f3 represents an effective focal length of the third lens.

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

-0.5<f1/f2<0；

wherein f1 represents an effective focal length of the first lens, and f2 represents an effective focal length of the second lens.

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

0.5<f1/f<1.1；

wherein f1 represents an effective focal length of the first lens.

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

-0.4<f/f2<0；

where f2 denotes an effective focal length of the second lens.

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

0.4<f/f4<0.7；

0.8<f5/f<8；

where f4 denotes an effective focal length of the fourth lens, and f5 denotes an effective focal length of the fifth lens.

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

1<f4/f5<4；

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

-50<f6/f<-1；

-1<f7/f<-0.5；

where f6 denotes an effective focal length of the sixth lens, and f7 denotes an effective focal length of the seventh lens.

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

1.5<f/EPD<1.8；

wherein EPD represents an entrance pupil diameter of the optical lens.

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

-5<R61/f<-0.5；

0.1<R61/R62<1；

wherein R61 denotes a radius of curvature of an object-side surface of the sixth lens element, and R62 denotes a radius of curvature of an image-side surface of the sixth lens element.

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

2.3<CT2/CT3<4.5；

1<DM2/DM3<1.2；

wherein CT2 represents a center thickness of the second lens, CT3 represents a center thickness of the third lens, DM2 represents an effective aperture of the second lens, and DM3 represents an effective aperture of the third lens.

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

DM4/DMi <1, i =1, 2, 3, 5, 6, or 7;

wherein DM1 represents an effective aperture of the first lens, DM2 represents an effective aperture of the second lens, DM3 represents an effective aperture of the third lens, DM4 represents an effective aperture of the fourth lens, DM5 represents an effective aperture of the fifth lens, DM6 represents an effective aperture of the sixth lens, DM7 represents an effective aperture of the seventh lens, and DMi represents an effective aperture of the i-th lens.