CN113791490A

CN113791490A - Optical lens and imaging apparatus

Info

Publication number: CN113791490A
Application number: CN202111365621.6A
Authority: CN
Inventors: 章彬炜; 钟培森; 曾昊杰
Original assignee: Jiangxi Lianyi Optics Co Ltd
Current assignee: Jiangxi Lianyi Optics Co Ltd
Priority date: 2021-11-18
Filing date: 2021-11-18
Publication date: 2021-12-14
Anticipated expiration: 2041-11-18
Also published as: CN113791490B

Abstract

The invention discloses an optical lens and imaging equipment, the optical lens includes from the object side to the imaging surface along the optical axis in turn: a diaphragm; the first lens with positive focal power has a convex object-side surface and a convex image-side surface; a second lens with negative focal power, wherein the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a convex surface; a third lens element having a positive optical power, an object-side surface being convex at a paraxial region and an image-side surface being concave at a paraxial region; a fourth lens element having a positive optical power, an object-side surface being convex at a paraxial region and an image-side surface being concave at a paraxial region, the fourth lens element having at least one inflection point on both the object-side surface and the image-side surface; wherein the entrance pupil diameter EPD of the optical lens is less than 1.4 mm; and the optical lens satisfies the following conditional expressions: 0.12< CT1/TTL < 0.35; where CT1 denotes the center thickness of the first lens, and TTL denotes the total optical length of the optical lens. The optical lens has the advantages of high pixel, miniaturization and low sensitivity.

Description

Optical lens and imaging apparatus

Technical Field

The present invention relates to the field of imaging lens technology, and in particular, to an optical lens and an imaging device.

Background

At present, along with the popularization of portable electronic equipment and the popularity of social, video and live broadcast software, people have higher and higher degrees of love for photography, a camera lens becomes a standard configuration of the electronic equipment, and the camera lens even becomes an index which is considered for the first time when consumers purchase the electronic equipment.

With the continuous development of mobile information technology, portable electronic devices such as mobile phones are also developing towards ultra-thin, full-screen, ultra-high definition imaging and the like, which puts higher demands on camera lenses carried on the portable electronic devices, and the camera lenses have sufficient optical performance and imaging capability and certain attractiveness, and the optical performance is improved while the camera lenses follow the change of the electronic devices. In recent years, the continuous development of special-shaped screens such as a water drop screen, a Liuhai screen and a hole digging screen is sourced from the enthusiasm pursuit of consumers for the whole screen of the mobile phone; there are many obstacles to the implementation of a full-face screen due to the presence of a front camera and the oversized head. The head size outer diameter of the common optical lens applied to the mobile phone in the market at present reaches ∅ 3mm at least, and the head outer diameter and the whole volume are large, so that the screen occupation ratio is difficult to improve, and better visual experience cannot be brought to consumers.

Disclosure of Invention

Therefore, the present invention is directed to an optical lens and an imaging device, which have at least advantages of small head outer diameter, small volume, high pixel height, and the like, so as to meet the usage requirements of a portable electronic device.

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

In a first aspect, the present invention provides an optical lens, comprising, in order from an object side to an image plane 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 convex surface; the second lens is provided with negative focal power, the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a convex surface; a third lens having a positive optical power, an object-side surface of the third lens being convex at a paraxial region and an image-side surface of the third lens being concave at a paraxial region; a fourth lens having a positive optical power, an object-side surface of the fourth lens being convex at a paraxial region, an image-side surface of the fourth lens being concave at a paraxial region; wherein an entrance pupil diameter EPD of the optical lens is <1.4 mm; and the optical lens satisfies the following conditional expression: 0.12< CT1/TTL < 0.35; CT1 denotes a center thickness of the first lens, and TTL denotes an optical total length of the optical lens.

In a second aspect, the present invention provides an imaging apparatus, comprising an imaging element and the optical lens provided in the first aspect, wherein the imaging element is configured to convert an optical image formed by the optical lens into an electrical signal.

Compared with the prior art, the optical lens and the imaging equipment provided by the invention adopt four lenses with specific focal power, adopt specific surface shape collocation and reasonable focal power distribution, meet high pixel and have more compact structure, the outer diameter of the head part of the lens can be made below ∅ 2mm, and the requirement of high screen occupation ratio can be met, so that the miniaturization of the lens and the balance of high pixels are better realized, simultaneously, scenes with larger area can be shot, great convenience is brought to later cutting, and the use requirement of portable electronic equipment can be better met.

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 graph showing the f-tan θ distortion of an optical lens according to a first embodiment of the present invention;

FIG. 3 is a field curvature graph of an optical lens according to a 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 graph showing the f-tan θ distortion of an optical lens according to a second embodiment of the present invention;

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

FIG. 8 is a 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 graph showing the f-tan θ distortion of an optical lens according to a third embodiment of the present invention;

FIG. 11 is a field curvature graph 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;

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

FIG. 14 is a graph showing the f-tan θ distortion of an optical lens according to a fourth embodiment of the present invention;

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

FIG. 16 is a vertical axis chromatic aberration diagram of an optical lens according to a fourth embodiment of the present invention;

fig. 17 is a schematic configuration diagram of an image forming apparatus according to a fifth embodiment of the present invention.

Detailed Description

In order to make the objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. Several embodiments of the invention are 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 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 convex surface;

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

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

the fourth lens has positive focal power, the object-side surface of the fourth lens is convex at a paraxial region, the image-side surface of the fourth lens is concave at the paraxial region, and both the object-side surface and the image-side surface of the fourth lens have at least one point of inflection;

wherein an entrance pupil diameter EPD of the optical lens is <1.4 mm; and the optical lens further satisfies the following conditional expressions:

0.12<CT1/TTL<0.35；（1）

wherein CT1 denotes a center thickness of the first lens, and TTL denotes an optical total length of the optical lens. The condition formula (1) is met, on one hand, the size of the head of the lens is reduced by properly adjusting the thickness ratio of the first lens, so that the outer diameter of the head can be below ∅ 2mm, the windowing size on a screen is reduced, and the screen ratio is improved; on the other hand, the length of the head of the lens is increased, the length of the rear part of the lens is effectively compressed, the overall occupied space of the lens is reduced, and the optical-mechanical design of the lens and the molding of the lens are facilitated.

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

0.5<DM1/f<0.65；（2）

where DM1 denotes the effective diameter of the first lens and f denotes the effective focal length of the optical lens. Satisfying the conditional expression (2), the optical lens is beneficial to reducing the head size of the optical lens while increasing the side view field of an object, and is beneficial to being applied to portable electronic products by maintaining miniaturization and wide view angle.

-4mm<(Nd2/Nd1)×f2<-2.5mm；（3）

where Nd1 denotes a refractive index of the first lens, Nd2 denotes a refractive index of the second lens, and f2 denotes an effective focal length of the second lens. The total track length of the optical system is effectively shortened by reasonably selecting the refractive indexes of the materials of the first lens and the second lens according to the conditional expression (3), and the positive spherical aberration generated by the first lens is properly balanced through the negative refractive power of the second lens, so that the aberration of the optical system can be corrected, and the imaging quality is favorably improved.

1.5<f1/CT1<5.5；（4）

-1<R11/R12<0；（5）

where CT1 denotes a center thickness of the first lens, f1 denotes an effective focal length of the first lens, R11 denotes a radius of curvature of an object-side surface of the first lens, and R12 denotes a radius of curvature of an image-side surface of the first lens. The condition formula (4) is satisfied, the projection height of the light on the image surface of the first lens is reduced, the aberration difference between different wavelengths can be effectively reduced, and the correction difficulty of chromatic aberration is reduced. The first lens is a positive refractive power lens, and when the conditional expression (5) is satisfied, the first lens can be biconvex, so that light rays can be better converged, the aperture of the first lens is smaller, and the miniaturization of the lens head is favorably realized.

1.2<CT1/ET1<1.8；（6）

0.3<CT1/DM1<1.0；（7）

where CT1 denotes the center thickness of the first lens, ET1 denotes the edge thickness of the first lens, and DM1 denotes the effective diameter of the first lens. Satisfy conditional expressions (6) and (7), through the limit thickness ratio and the bore ratio of reasonable setting first lens, be favorable to reducing the tolerance sensitivity of first lens to promote the processing characteristic of first lens, improve the product yield.

0<R21/R22<0.4；（8）

-10<(R21+R22)/f<-1；（9）

where R21 denotes a radius of curvature of an object-side surface of the second lens, R22 denotes a radius of curvature of an image-side surface of the second lens, and f denotes an effective focal length of the optical lens. The second lens is a meniscus lens by controlling the surface shape of the second lens, which satisfies conditional expressions (8) and (9), is helpful to reduce the sensitivity of the system, improves the production yield, and can correct the aberration of the front and rear positive lenses, thereby improving the imaging quality.

0.5<R31/R32<1；（10）

0.1<(SAG31-SAG32)/CT3 <0.8；（11）

where R31 denotes a radius of curvature of an object-side surface of the third lens, R32 denotes a radius of curvature of an image-side surface of the third lens, SAG31 denotes an edge rise of the object-side surface of the third lens, SAG32 denotes an edge rise of the image-side surface of the third lens, and CT3 denotes a center thickness of the third lens. The surface shape of the third lens at the position close to the optical axis can be controlled to be convex-concave when the conditional expressions (10) and (11) are met, so that the function of converging light rays is achieved, the correction of field curvature and distortion is facilitated, the imaging quality is improved, and the third lens has certain advantages compared with the existing mainstream concave-convex shape; meanwhile, the shape change of the third lens can be slowed down by adjusting the surface shape of the surface of the third lens close to the optical axis, the generation of stray light is reduced, and the formability of the lens is improved.

0.2<R41/DM4<0.35；（12）

where R41 denotes a radius of curvature of an object side surface of the fourth lens, and DM4 denotes an effective diameter of the fourth lens. When the conditional expression (12) is satisfied, the suppression of ghost and the optimization of aberration are facilitated by controlling the surface shape of the fourth lens.

0<IH-f×tan(θ)<0.01mm；（13）

where IH denotes an actual half image height of the optical lens, θ denotes a half field angle of the optical lens, and f denotes an effective focal length of the optical lens. The conditional expression (13) is satisfied, which shows that the system distortion is well inhibited under the effect of large field angle of the optical imaging system; if the IH-f multiplied by tan (theta) value exceeds the lower limit, the optical imaging system has larger negative distortion, the shooting graph can generate obvious deformation and become a barrel shape, and the imaging effect is influenced; if the IH-f multiplied by tan (theta) value exceeds the upper limit, the optical imaging system has larger positive distortion, the shot graph can generate obvious deformation and form a pillow shape, and the imaging effect is influenced.

0.7<f1/f<1.2；（14）

-1.5<f2/f<-0.8；（15）

1.5<f3/f<3；（16）

2<f4/f<10；（17）

where f1 denotes an effective focal length of the first lens, f2 denotes an effective focal length of the second lens, f3 denotes an effective focal length of the third lens, f4 denotes an effective focal length of the fourth lens, and f denotes an effective focal length of the optical lens. The first lens element with positive refractive power, the second lens element with negative refractive power, the third lens element with positive refractive power, and the fourth lens element with positive refractive power satisfy conditional expressions (14) to (17), and the refractive powers of the respective lens elements are reasonably arranged to enhance coma aberration correction in the off-axis field of view, and to improve the image quality by converging the field curvature well.

As an implementation mode, a matching structure of four plastic lenses is adopted, so that the lens can be ensured to have a good imaging effect while the miniaturization, small head and low sensitivity are realized. The first lens, the second lens, the third lens and the fourth lens are plastic aspheric lenses, and the aspheric lenses are adopted, so that the cost can be effectively reduced, the 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.

In each embodiment of the present invention, the aspherical surface type of each lens 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.

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 image plane along an optical axis, a stop ST, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a filter G1.

The first lens element L1 has positive refractive power, the object-side surface S1 of the first lens element is convex, and the image-side surface S2 of the first lens element is convex;

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

the third lens L3 has positive optical power, with an object-side surface S5 of the third lens being convex at the paraxial region and an image-side surface S6 of the third lens being concave at the paraxial region;

the fourth lens L4 has positive optical power, the object-side surface S7 of the fourth lens is convex at the paraxial region, the image-side surface S8 of the fourth lens is concave at the paraxial region, and both the object-side surface S7 and the image-side surface S8 of the fourth lens L4 have an inflection point;

the first lens element L1, the second lens element L2, the third lens element L3 and the fourth lens element L4 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

Referring to fig. 2, fig. 3 and fig. 4, which are a f-tan θ distortion graph, a field curvature graph and a vertical axis chromatic aberration graph of the optical lens 100, respectively, it can be seen from fig. 2 that the optical distortion is controlled within ± 1.5%, which indicates that the distortion of the optical lens 100 is well corrected; it can be seen from fig. 3 that the curvature of field is controlled within ± 0.05mm, which indicates that the curvature of field of the optical lens 100 converges well; it can be seen from fig. 4 that the vertical axis chromatic aberration at different wavelengths is controlled within ± 1.7 μm, which indicates that the vertical axis chromatic aberration of the optical lens 100 is well corrected; 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

As shown in fig. 5, which is a schematic structural diagram of the optical lens 200 provided in the present embodiment, the optical lens 200 of the present embodiment is substantially the same as the first embodiment, and mainly differs in design parameters.

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

TABLE 3

In this embodiment, aspheric parameters of each lens in the optical lens 200 are shown in table 4.

TABLE 4

Referring to fig. 6, 7 and 8, which are a f-tan θ distortion graph, a field curvature graph and a vertical axis chromatic aberration graph of the optical lens 200, respectively, it can be seen from fig. 6 that the optical distortion is controlled within ± 1%, which indicates that the distortion of the optical lens 200 is well corrected; it can be seen from fig. 7 that the curvature of field is controlled within ± 0.05mm, which indicates that the curvature of field of the optical lens 200 converges well; it can be seen from fig. 8 that the vertical chromatic aberration at different wavelengths is controlled within ± 2.5 μm, which indicates that the vertical chromatic aberration of the optical lens 200 is well corrected; 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

As shown in fig. 9, which is a schematic structural diagram of the optical lens 300 provided in the present embodiment, the optical lens 300 of the present embodiment is substantially the same as the first embodiment, and mainly differs in design parameters.

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

Referring to fig. 10, fig. 11 and fig. 12, which are a f-tan θ distortion graph, a field curvature graph and a vertical axis chromatic aberration graph of the optical lens 300, respectively, it can be seen from fig. 10 that the optical distortion is controlled within ± 2%, which indicates that the distortion of the optical lens 300 is well corrected; it can be seen from fig. 11 that the curvature of field is controlled within ± 0.1mm, which indicates that the curvature of field of the optical lens 300 converges well; it can be seen from fig. 12 that the vertical axis chromatic aberration at different wavelengths is controlled within ± 2 μm, which indicates that the vertical axis chromatic aberration of the optical lens 300 is well corrected; 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.

Fourth embodiment

As shown in fig. 13, which is a schematic structural diagram of the optical lens 400 provided in the present embodiment, the optical lens 400 of the present embodiment is substantially the same as the first embodiment, and mainly differs in design parameters.

Specifically, the design parameters of the optical lens 400 provided in this embodiment are shown in table 7.

TABLE 7

In this embodiment, aspheric parameters of each lens in the optical lens 400 are shown in table 8.

TABLE 8

Referring to fig. 14, fig. 15 and fig. 16, which are a f-tan θ distortion graph, a field curvature graph and a vertical axis chromatic aberration graph of the optical lens 400, respectively, it can be seen from fig. 14 that the optical distortion is controlled within ± 1.5%, which indicates that the distortion of the optical lens 400 is well corrected; it can be seen from fig. 15 that the curvature of field is controlled within ± 0.05mm, which indicates that the curvature of field of the optical lens 400 converges well; it can be seen from fig. 16 that the vertical axis chromatic aberration at different wavelengths is controlled within ± 2 μm, which indicates that the vertical axis chromatic aberration of the optical lens 400 is well corrected; it can be seen from fig. 14, 15 and 16 that the aberrations of the optical lens 400 are well balanced, and the optical imaging quality is good.

Please refer to table 9, which shows the optical characteristics corresponding to the optical lens provided in the above four embodiments, including the field angle 2 θ, the total optical length TTL, the actual half-image height IH, the effective focal length F, the F # and the entrance pupil diameter EPD of the optical lens, and the related values corresponding to each of the above conditional expressions.

TABLE 9

In summary, the optical lens provided by the embodiment of the invention effectively shortens the overall length of the optical lens and corrects the aberration of the optical lens by reasonably matching the lens shapes, materials and focal power combinations among the lenses, so that the optical lens provided by the embodiment of the invention has the advantages of high pixel, miniaturization, low sensitivity and the like, and has good applicability to mobile phone electronic devices.

Fifth embodiment

Referring to fig. 17, an imaging apparatus 500 according to a fifth embodiment of the present invention is shown, where the imaging apparatus 500 may include an imaging element 510 and an optical lens (e.g., the optical lens 100) in any of the embodiments described above. The imaging element 510 may be a CMOS (Complementary Metal Oxide Semiconductor) image sensor, and may also be a CCD (Charge Coupled Device) image sensor.

The imaging device 500 may be a mobile phone, a tablet, a camera, or any other electronic device with the optical lens mounted thereon.

The embodiment provides an imaging apparatus 500 including the optical lens 100, and since the optical lens 100 has advantages of high pixel, miniaturization and low sensitivity, the imaging apparatus 500 having the optical lens 100 also has advantages of high pixel, miniaturization and low sensitivity.

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 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;

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 convex surface;

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

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

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

wherein an entrance pupil diameter EPD of the optical lens is <1.4 mm; and the optical lens satisfies the following conditional expression:

0.12<CT1/TTL<0.35；

wherein CT1 represents the center thickness of the first lens, and TTL represents the total optical length of the optical lens.

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

0.5<DM1/f<0.65；

where DM1 represents the effective diameter of the first lens and f represents the effective focal length of the optical lens.

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

-4mm<(Nd2/Nd1)×f2<-2.5mm；

where Nd1 denotes a refractive index of the first lens, Nd2 denotes a refractive index of the second lens, and f2 denotes an effective focal length of the second lens.

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

1.5<f1/CT1<5.5；

-1<R11/R12<0；

wherein CT1 denotes a center thickness of the first lens, f1 denotes an effective focal length of the first lens, R11 denotes a radius of curvature of an object-side surface of the first lens, and R12 denotes a radius of curvature of an image-side surface of the first lens.

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

1.2<CT1/ET1<1.8；

0.3<CT1/DM1<1.0；

wherein CT1 represents the center thickness of the first lens, ET1 represents the edge thickness of the first lens, and DM1 represents the effective diameter of the first lens.

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

0<R21/R22<0.4；

-10<(R21+R22)/f<-1；

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

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

0.5<R31/R32<1；

0.1<(SAG31-SAG32)/CT3 <0.8；

wherein R31 represents a radius of curvature of an object-side surface of the third lens, R32 represents a radius of curvature of an image-side surface of the third lens, SAG31 represents an edge rise of the object-side surface of the third lens, SAG32 represents an edge rise of the image-side surface of the third lens, and CT3 represents a center thickness of the third lens.

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

0.2<R41/DM4<0.35；

wherein R41 represents the radius of curvature of the object side surface of the fourth lens and DM4 represents the effective diameter of the fourth lens.

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

0<IH-f×tan(θ)<0.01mm；

where IH denotes an actual half image height of the optical lens, θ denotes a half field angle of the optical lens, and f denotes an effective focal length of the optical lens.

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

0.7<f1/f<1.2；

-1.5<f2/f<-0.8；

1.5<f3/f<3；

2<f4/f<10；

wherein f1 denotes an effective focal length of the first lens, f2 denotes an effective focal length of the second lens, f3 denotes an effective focal length of the third lens, f4 denotes an effective focal length of the fourth lens, and f denotes an effective focal length of the optical lens.

11. An imaging apparatus comprising the optical lens according to any one of claims 1 to 10 and an imaging element for converting an optical image formed by the optical lens into an electric signal.