CN116400478A

CN116400478A - Optical lens

Info

Publication number: CN116400478A
Application number: CN202310131022.0A
Authority: CN
Inventors: 谢雨辰; 徐丽丽; 章彬炜
Original assignee: Jiangxi Lianyi Optics Co Ltd
Current assignee: Jiangxi Lianyi Optics Co Ltd
Priority date: 2023-02-17
Filing date: 2023-02-17
Publication date: 2023-07-07

Abstract

The invention discloses an optical lens, which consists of five lenses, and sequentially comprises the following components from an object side to an imaging surface along an optical axis: a diaphragm; a first lens with positive focal power, the object side surface of which is a convex surface; a second lens having negative optical power, both the object-side surface and the image-side surface of which are concave surfaces; a third lens element with positive refractive power having a convex object-side surface and a concave image-side surface; a fourth lens element with positive refractive power having convex object-side and image-side surfaces; a fifth lens element with negative refractive power having a concave object-side surface and a convex image-side surface; wherein, the optical lens satisfies the conditional expression: 5< f3/f4<60, f3 denotes a focal length of the third lens, and f4 denotes a focal length of the fourth lens. The optical lens provided by the invention has the characteristics of long focal length and large image surface by reasonably setting the focal length and the surface shape of each lens, can realize the effect of background blurring and long-distance high-definition imaging, and can well meet the requirement of telephoto.

Description

Optical lens

Technical Field

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

Background

Currently, with the popularization of portable electronic devices and the popularity of social, video and live broadcast software, people have a higher and higher preference for photography, and a camera lens has become a standard of the electronic devices, and even has become an index of primary consideration when consumers purchase the electronic devices.

With the continuous development of mobile information technology and the rapid development of electronic devices such as smart phones, tablet computers and electronic readers, the requirements of the industry on the camera shooting function of the electronic devices are higher and higher, and the camera shooting lens with various characteristics can adapt to different application scenes and meet different shooting requirements. In recent years, as the requirements of consumers on photographing effects of electronic equipment are continuously improved, besides the requirement of high pixels, a space feeling during photographing is pursued, so that a main body can be highlighted, the advantage of a tele lens is displayed, a photographing lens with tele characteristics can photograph far scenes, effectively blurring the background and highlighting the main body, the imaging quality of the far scenes is improved, and the requirement of tele is met.

However, although the common five-lens optical lens has better optical performance, the common five-lens optical lens cannot better meet the design requirements of long focal length and large image plane, has poor long-distance shooting effect, and influences the shooting experience of users.

Disclosure of Invention

Based on the above, the present invention is to provide an optical lens with at least the advantages of long focal length, large image plane and high pixel.

The invention achieves the above object by the following technical scheme.

The invention provides an optical lens, which consists of five lenses, and sequentially comprises the following components from an object side to an imaging surface along an optical axis: a diaphragm; a first lens with positive focal power, wherein the object side surface of the first lens is a convex surface; a second lens with negative focal power, wherein the object side surface and the image side surface of the second lens are concave surfaces; a third lens with positive focal power, wherein the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface; a fourth lens with positive focal power, wherein an object side surface and an image side surface of the fourth lens are both convex surfaces; a fifth lens with negative focal power, wherein an object side surface of the fifth lens is a concave surface, and an image side surface of the fifth lens is a convex surface; the optical lens satisfies the following conditional expression: 5< f3/f4<60, f3 denotes a focal length of the third lens, and f4 denotes a focal length of the fourth lens.

Compared with the prior art, the optical lens provided by the invention adopts five lenses with specific focal power, and the lens has longer focal length while meeting the requirement of a large image plane by reasonably matching each surface shape and the focal power distribution, so that the effects of background blurring and long-distance high-definition imaging can be realized, and the requirement of telephoto can be well met; meanwhile, the thickness of each lens and the distance between the lenses are reasonably controlled, so that the structure of the lens is compact, and the total length is small.

Drawings

The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in 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 graph showing a field curvature of an optical lens according to a first embodiment of the present invention;

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

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

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

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

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

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

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

fig. 10 is a graph showing a field curve of an optical lens according to a third embodiment of the present invention:

FIG. 11 is a graph showing optical distortion of an optical lens according to a third embodiment of the present invention;

FIG. 12 is a graph of the vertical chromatic aberration of an optical lens according to a third embodiment of the present invention;

fig. 13 is a schematic structural diagram of an optical lens according to a fourth embodiment of the present invention;

fig. 14 is a graph showing a field curve of an optical lens according to a fourth embodiment of the present invention:

FIG. 15 is a graph showing optical distortion of an optical lens according to a fourth embodiment of the present invention;

fig. 16 is a graph showing a vertical axis chromatic aberration curve of an optical lens according to a fourth embodiment of the present invention.

Detailed Description

In order that the objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Several embodiments of the invention are presented in the figures. 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.

Herein, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position is not defined, then the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is referred to as the object side of the lens, and the surface of each lens closest to the imaging plane is referred to as the image side of the lens.

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

The invention provides an optical lens, which sequentially comprises from an object side to an imaging surface along an optical axis: the optical lens comprises a diaphragm, a first lens, a second lens, a third lens, a fourth lens, a fifth lens and an optical filter.

The first lens can have positive focal power, and the object side surface of the first lens is a convex surface; the second lens can have negative focal power, and the object side surface and the image side surface of the second lens are concave; the third lens element with positive refractive power has a convex object-side surface and a concave image-side surface; the fourth lens element may have positive refractive power, and both object-side and image-side surfaces thereof may be convex; the fifth lens element with negative refractive power has a concave object-side surface and a convex image-side surface; the focal length and the surface type distribution of the first lens to the fifth lens are reasonably distributed, so that the deflection angle of light rays can be effectively reduced, the light difference sensitivity of each lens is reduced, and the imaging quality of an optical system is improved.

According to the optical lens provided by the invention, five lenses with specific focal power are adopted, and through reasonable matching of the surface shapes and the focal power distribution, the lens has a longer focal length while meeting a large image plane, so that the effects of background blurring and long-distance high-definition imaging can be realized, and the requirement of a telephoto can be well met.

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

5<f3/f4<60；

wherein f3 represents a focal length of the third lens, and f4 represents a focal length of the fourth lens. The optical powers of the third lens and the fourth lens are reasonably controlled to effectively balance aberration generated by the front lens, improve the resolving power of the lens and enhance the depth feeling of a shot picture.

0.3<f1/f<0.6；

-0.2<R11/R12<0.2；

wherein f1 represents a focal length of the first lens, f represents an effective focal length of the optical lens, R11 represents a radius of curvature of an object side surface of the first lens, and R12 represents a radius of curvature of an image side surface of the first lens. The axial aberration of the system can be reduced by meeting the conditions, the high-definition effect of the lens in long-distance shooting can be realized, and the long-focus characteristic can be realized better.

-2<f1/f2<-1.1；

wherein f1 represents the focal length of the first lens, and f2 represents the focal length of the second lens. The residual error after balancing the negative spherical aberration generated by the first lens and the positive spherical aberration generated by the second lens can be controlled within a reasonable range by reasonably setting the focal length duty ratio of the first lens and the second lens, so that the correction difficulty of the aberration of the subsequent lens is reduced, and the imaging quality of the lens near the optical axis is improved.

-0.5<f2/f<-0.1；

-10<R21/R22<-1；

wherein f2 represents a focal length of the second lens, f represents an effective focal length of the optical lens, R21 represents a radius of curvature of an object side surface of the second lens, and R22 represents a radius of curvature of an image side surface of the second lens. The second lens is arranged to be a biconcave negative lens, so that the tortuosity of light rays entering the second lens can be slowed down, the optical distortion of the optical lens can be corrected, and the overall imaging quality is improved.

1<f3/f<30；

0.8<R31/R32<1.3；

wherein f3 denotes a focal length of the third lens, f denotes an effective focal length of the optical 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 third lens has proper focal power and surface shape, which is beneficial to correcting field curvature and improving the resolution quality of the optical lens.

-0.1<f2/f3<0，

wherein f2 represents the focal length of the second lens, and f3 represents the focal length of the third lens. The range is satisfied, and the aberration of the system can be balanced by reasonably distributing the focal length ratio of the second lens and the third lens, so that the optical system has higher imaging quality of pixels.

0.3<f4/f<0.8；

-2<R41/R42<-0.2；

wherein f4 denotes a focal length of the fourth lens, f denotes an effective focal length of the optical lens, R41 denotes a radius of curvature of an object side surface of the fourth lens, and R42 denotes a radius of curvature of an image side surface of the fourth lens. The lens meets the above range, and the focal power and the surface shape of the fourth lens are reasonably controlled, so that the deflection degree of light rays in the fourth lens is reduced, the sensitivity of the lens is reduced, and the lens has good correcting capability on high-order aberration, so that the long focus and high-pixel balance of the lens are better realized.

-1.5<f5/f<-0.7；

0.4<R51/R52<0.7；

where f5 denotes a focal length of the fifth lens, f denotes an effective focal length of the optical 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. The range is satisfied, so that the fifth lens element has proper negative refractive power and surface shape, which is beneficial to increasing the incidence angle of light on the imaging surface and better realizing the imaging effect of the lens element on the large image surface.

-0.8<f4/f5<-0.3；

wherein f4 represents the focal length of the fourth lens, and f5 represents the focal length of the fifth lens. The optical lens can be used for compensating the aberration generated by the positive lens and the negative lens by reasonably matching the focal lengths of the fourth lens and the fifth lens, thereby providing convenience for correcting the curvature of field, astigmatism and spherical aberration of the optical lens.

The high-order aberration of the optical lens is corrected, and high-pixel imaging of the lens is realized.

3<f/IH<4；

FOV<30°；

where f represents an effective focal length of the optical lens, IH represents an actual half-image height of the optical lens on an imaging plane, and FOV represents a maximum field angle of the optical lens. The method meets the above range, and can better realize the balance of the long focus and the large image plane of the lens by reasonably controlling the relation between the effective focal length and the image height of the lens, thereby realizing the effects of background blurring and long-distance imaging and simultaneously ensuring the high-definition quality of pictures when shooting with the lens.

0.45<BFL/TTL<0.55；

wherein BFL represents an air space between an image side surface of the fifth lens and the imaging surface on the optical axis, and TTL represents an optical total length of the optical lens. The range is met, and through setting a larger optical back focus, a sufficient space can be reserved for the turning optical path of the optical system, so that the reduction of the overall thickness of the lens is realized.

And the back focus of the optical system is reasonably distributed, so that the length of the optical system is reduced, the mounting interference between the lens and the chip is reduced, and the assembly yield is improved.

9mm<(f×IH)/f1<11mm；

wherein f represents the effective focal length of the optical lens, IH represents the actual half-image height of the optical lens on the imaging surface, and f1 represents the focal length of the first lens. Satisfying the above range, by reasonably controlling the value of (f×ih)/f 1, it is beneficial to obtain a larger system focal length, and at the same time, it is beneficial to obtain a larger imaging surface, which means that it is possible to provide a higher image resolution, so that the lens can match with a chip of a higher pixel, and realize an imaging effect of a high pixel.

TTL/f<1.0；

wherein TTL represents the total optical length of the optical lens, and f represents the effective focal length of the optical lens. The method meets the conditions, ensures that the system achieves miniaturization, has good imaging effect and achieves the characteristic of large image plane.

In some embodiments, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens each employ an aspherical lens. By adopting the aspheric lens, aberration can be effectively corrected, imaging quality is improved, and an optical performance product with higher cost performance is provided.

In various embodiments of the present invention, when an aspherical lens is used as a lens in an optical lens, the surface shape of the aspherical lens satisfies the following equation:

wherein z is the sagittal height from the apex of the aspherical surface when the aspherical surface is at a position of height h in the optical axis direction, c is the paraxial curvature of the surface, k is the conic coefficient conic, A _2i The aspherical surface profile coefficient of the 2 i-th order.

The invention is further illustrated in the following examples. In various embodiments, the thickness, radius of curvature, and material selection portion of each lens in the optical lens may vary, and for specific differences, reference may be made to the parameter tables of the various embodiments. The following examples are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following examples, and any other changes, substitutions, combinations or simplifications that do not depart from the gist of the present invention are intended to be equivalent substitutes within the scope of the present invention.

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 includes, in order from an object side to an imaging surface S13 along an optical axis: stop ST, first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, and filter G1.

The first lens element L1 has positive refractive power, wherein an object-side surface S1 thereof is convex, and an image-side surface S2 thereof is concave;

the second lens element L2 has negative refractive power, wherein an object-side surface S3 thereof is concave, and an image-side surface S4 thereof is concave;

the third lens element L3 has positive refractive power, wherein an object-side surface S5 thereof is convex, and an image-side surface S6 thereof is concave;

the fourth lens element L4 has positive refractive power, wherein an object-side surface S7 thereof is convex, and an image-side surface S8 thereof is convex;

the fifth lens element L5 has negative refractive power, wherein an object-side surface S9 thereof is concave and an image-side surface S10 thereof is convex; the object side surface of the filter G1 is S11, and the image side surface is S12.

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

The relevant parameters of each lens in the optical lens 100 according to the first embodiment of the present invention are shown in table 1.

TABLE 1

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

TABLE 2

In the present embodiment, a field curvature graph, an optical distortion graph, and a vertical axis color difference graph of the optical lens 100 are shown in fig. 2, 3, and 4, respectively.

Fig. 2 shows a curvature of field curve of the optical lens 100 in this embodiment, which indicates the extent of curvature of the meridional image plane and the sagittal image plane, and it can be seen from the figure that curvature of field of the image planes in two directions is controlled within ±0.10mm, which indicates that curvature of field of the optical lens 100 is well corrected.

Fig. 3 shows optical distortion curves of the optical lens 100 of the present embodiment, which represent distortions at different image heights on the imaging plane, and it can be seen from the figure that the optical distortion is controlled within ±1.5%, which indicates that the distortion of the optical lens 100 is well corrected.

Fig. 4 shows a paraxial color difference curve of the optical lens 100 of the present embodiment, which represents the paraxial color difference value between the light with different wavelengths and the dominant wavelength, and it can be seen from the figure that the paraxial color difference value of each wavelength is within ±1.0 μm, which indicates that the paraxial color difference of the optical lens 100 is well corrected.

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, and the optical lens 200 according to the present embodiment is substantially the same as the first embodiment described above, and the difference is mainly that the radius of curvature, the lens thickness, the pitch, etc. of each lens face are different.

Specifically, the relevant parameters of each lens in the optical lens 200 of the present embodiment are shown in table 3.

TABLE 3 Table 3

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

TABLE 4 Table 4

In the present embodiment, a field curvature graph, an optical distortion graph, and a vertical axis chromatic aberration graph of the optical lens 200 are shown in fig. 6, 7, and 8, respectively. As can be seen from fig. 6, the curvature of field of the meridional image plane and the sagittal image plane are controlled within ±0.10mm, which indicates that the curvature of field of the optical lens 200 is well corrected. As can be seen from fig. 7, the optical distortion is controlled within ±1.5%, indicating that the distortion of the optical lens 200 is well corrected. As can be seen from fig. 8, the vertical chromatic aberration of each wavelength is within ±1.5 μm, indicating that the vertical chromatic aberration of the optical lens 200 is well corrected.

Third embodiment

Referring to fig. 9, a schematic diagram of an optical lens 300 according to a third embodiment of the present invention is shown, and the optical lens 300 of the present embodiment is substantially the same as the first embodiment described above, and the main difference is that. The image side surface S2 of the first lens element is convex at a paraxial region, and the curvature radius, lens thickness, pitch, and the like of each lens element are different.

Specifically, the relevant parameters of each lens in the optical lens 300 of the present embodiment are shown in table 5.

TABLE 5

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

TABLE 6

In the present embodiment, a field curvature graph, an optical distortion graph, and a vertical axis chromatic aberration graph of the optical lens 300 are shown in fig. 10, 11, and 12, respectively. As can be seen from fig. 10, the curvature of field of the meridional image plane and the sagittal image plane are controlled within ±0.1mm, which indicates that the curvature of field of the optical lens 300 is well corrected. As can be seen from fig. 11, the optical distortion is controlled within ±1.5%, indicating that the distortion of the optical lens 300 is well corrected. As can be seen from fig. 12, the vertical chromatic aberration of each wavelength is within ±1.0 μm, indicating that the vertical chromatic aberration of the optical lens 300 is well corrected.

Fourth embodiment

Referring to fig. 13, a schematic diagram of an optical lens 400 according to a fourth embodiment of the present invention is shown, and the optical lens 400 according to the present embodiment is substantially the same as the first embodiment described above, and is mainly different in the radius of curvature, lens thickness, pitch, etc. of each lens surface.

Specifically, the parameters of each lens in the optical lens 400 of the present embodiment are shown in table 7

TABLE 7

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

TABLE 8

In the present embodiment, a field curvature graph, an optical distortion graph, and a vertical axis chromatic aberration graph of the optical lens 400 are shown in fig. 14, 15, and 16, respectively. As can be seen from fig. 14, the curvature of field of the meridional image plane and the sagittal image plane are controlled within ±0.1mm, which indicates that the curvature of field of the optical lens 400 is well corrected. As can be seen from fig. 15, the optical distortion is controlled within ±1.0%, indicating that the distortion of the optical lens 400 is well corrected. As can be seen from fig. 16, the vertical chromatic aberration of each wavelength is within ±1.0 μm, indicating that the vertical chromatic aberration of the optical lens 400 is well corrected.

Table 9 is an optical characteristic corresponding to the above four embodiments, and mainly includes an effective focal length F, an f#, an optical total length TTL, an image height IH corresponding to a maximum field angle FOV and a half field angle, and a value corresponding to each of the above conditional expressions.

TABLE 9

In summary, the optical lens provided by the invention adopts five lenses with specific focal power, and by reasonably matching each surface shape and focal power distribution, the lens has longer focal length while meeting the requirement of a large image plane, thereby realizing the effects of background blurring and long-distance high-definition imaging and well meeting the requirement of telephoto; meanwhile, by reasonably controlling the thickness of each lens and the distance between lenses, the structure of the lens is compact, and the total length is small; meanwhile, by reasonably configuring the distance between the lenses, the spacer is not needed to bear between the lenses, the use of single-part products is reduced, the spacer stray light is avoided, the cost is saved, and the imaging quality is improved.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., 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 present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. 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 represent only a few embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the present invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. The scope of the invention should therefore be pointed out in the appended claims.

Claims

1. An optical lens comprising five lenses, comprising, in order from an object side to an imaging plane along an optical axis:

a diaphragm;

a first lens with positive focal power, wherein the object side surface of the first lens is a convex surface;

a second lens with negative focal power, wherein the object side surface and the image side surface of the second lens are concave surfaces;

a third lens with positive focal power, wherein the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface;

a fourth lens with positive focal power, wherein an object side surface and an image side surface of the fourth lens are both convex surfaces;

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

wherein, the optical lens satisfies the conditional expression: 5< f3/f4<60, f3 denotes a focal length of the third lens, and f4 denotes a focal length of the fourth lens.

2. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional expression:

0.3<f1/f<0.6；

-0.2<R11/R12<0.2；

wherein f1 represents a focal length of the first lens, f represents an effective focal length of the optical lens, R11 represents a radius of curvature of an object side surface of the first lens, and R12 represents a radius of curvature of an image side surface of the first lens.

3. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional expression:

-2<f1/f2<-1.1；

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

4. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional expression:

-0.5<f2/f<-0.1；

-10<R21/R22<-1；

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

5. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional expression:

1<f3/f<30；

0.8<R31/R32<1.3；

wherein f3 denotes a focal length of the third lens, f denotes an effective focal length of the optical 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. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional expression:

-0.1<f2/f3<0，

wherein f2 represents the focal length of the second lens, and f3 represents the focal length of the third lens.

7. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional expression:

0.3<f4/f<0.8；

-2<R41/R42<-0.2；

wherein f4 denotes a focal length of the fourth lens, f denotes an effective focal length of the optical lens, R41 denotes a radius of curvature of an object side surface of the fourth lens, and R42 denotes a radius of curvature of an image side surface of the fourth lens.

8. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional expression:

-1.5<f5/f<-0.7；

0.4<R51/R52<0.7；

where f5 denotes a focal length of the fifth lens, f denotes an effective focal length of the optical 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.

9. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional expression:

-0.8<f4/f5<-0.3；

wherein f4 represents the focal length of the fourth lens, and f5 represents the focal length of the fifth lens.

10. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional expression:

3<f/IH<4；

where f represents an effective focal length of the optical lens, and IH represents an actual half-image height of the optical lens on an imaging plane.

11. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional expression:

0.45<BFL/TTL<0.55；

wherein BFL represents an air space between an image side surface of the fifth lens and the imaging surface on the optical axis, and TTL represents an optical total length of the optical lens.