CN112099206B

CN112099206B - Optical lens and imaging apparatus

Info

Publication number: CN112099206B
Application number: CN202011316802.5A
Authority: CN
Inventors: 王义龙; 刘绪明; 曾昊杰; 曾吉勇
Original assignee: Jiangxi Lianyi Optics Co Ltd
Current assignee: Jiangxi Lianyi Optics Co Ltd
Priority date: 2020-11-23
Filing date: 2020-11-23
Publication date: 2021-02-05
Anticipated expiration: 2040-11-23
Also published as: WO2022105926A1; CN112099206A

Abstract

The invention discloses an optical lens and imaging equipment, the optical lens comprises the following components in sequence from an object side to an imaging surface: the first lens with negative focal power has a convex object-side surface and a concave image-side surface; the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; a third lens having a positive refractive power, both the object-side surface and the image-side surface of the third lens being convex; a diaphragm; the image side surface of the fourth lens is a convex surface; a fifth lens element with negative optical power, having a concave object-side surface and a convex image-side surface at a paraxial region; a sixth lens element with negative optical power having a convex object-side surface at the paraxial region and a concave image-side surface at the paraxial region. According to the optical lens, through reasonable matching of the shapes and focal powers of six lenses with specific refractive power, the field angle of the optical lens reaches more than 150 degrees, the total optical length is less than 6mm, the balance of a large wide angle, a small volume and high pixels is well realized, and the shooting experience of a user is effectively improved.

Description

Optical lens and imaging apparatus

Technical Field

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

Background

At present, along with the popularization of portable electronic devices (such as smart phones, tablets and cameras), and the popularity of social, video and live broadcast software, people have higher and higher liking degree for photography, camera lenses have become standard fittings of the electronic devices, and even the camera lenses have become indexes which are considered for the first time when consumers purchase the electronic devices.

With the continuous development of mobile information technology, portable electronic devices such as mobile phones are also developing towards ultra-wide-angle and ultra-high definition imaging, which puts higher demands on camera lenses mounted on the portable electronic devices. However, in recent years, with the enthusiasm of consumers for taking pictures of mobile phones, the high pixels of the rear camera have already gone to the peak, and the development towards higher pixels will be subject to the mutual restriction of the lightness and thinness of the mobile phone and the limitation of the total length of the camera, so that the mobile phone with an ultra-wide angle and even a fisheye lens mounted on the rear of the mobile phone may become a surge; how to realize the balance of large wide angle, high pixel and small volume of the camera lens becomes a problem to be solved urgently.

Disclosure of Invention

To this end, an object of the present invention is to provide an optical lens and an imaging apparatus for solving the above problems.

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: the lens comprises a first lens with negative 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; the second lens with negative focal power is characterized in that the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; a third lens having a positive optical power, the third lens having convex object and image side surfaces; a diaphragm; the fourth lens is provided with positive focal power, the object side surface of the fourth lens is a concave surface or a convex surface, and the image side surface of the fourth lens is a convex surface; a fifth lens element having a negative optical power, the fifth lens element having a concave object-side surface and a convex image-side surface at a paraxial region; a sixth lens having a negative optical power, an object-side surface of the sixth lens being convex at a paraxial region and an image-side surface of the sixth lens being concave at the paraxial region; wherein, the total optical length TTL of the optical lens is less than 6.0mm, and the maximum field angle FOV of the optical lens is more than or equal to 150 degrees.

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 device provided by the invention have the advantages that through reasonable collocation of the shapes and focal powers of six lenses with specific refractive power, the field angle of the optical lens reaches more than 150 degrees, the total optical length is less than 6mm, the structure is more compact while high pixels are met, the balance of large wide angle, small volume and high pixels is better realized, the use requirement of portable electronic equipment can be met, and the shooting experience of a user is effectively improved.

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 system 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 of on-axis spherical aberration 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 field curvature graph of an optical lens according to a second embodiment of the present invention;

FIG. 7 is a graph of on-axis spherical aberration 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 of on-axis spherical aberration 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 field curvature graph of an optical lens according to a fourth embodiment of the present invention;

FIG. 15 is a graph of on-axis spherical aberration 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 structural view of an image forming apparatus provided in 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. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The invention provides an optical lens, which sequentially comprises the following components from an object side to an imaging surface along an optical axis: the first lens with negative focal power has a convex object-side surface and a concave image-side surface; the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; a third lens having a positive refractive power, both the object-side surface and the image-side surface of the third lens being convex; a diaphragm; the object side surface of the fourth lens is a concave surface or a convex surface, and the image side surface of the fourth lens is a convex surface; a fifth lens element with negative optical power, having a concave object-side surface and a convex image-side surface at a paraxial region; and a sixth lens element having a negative power, an object-side surface of which is convex at a paraxial region and an image-side surface of which is concave at the paraxial region; wherein, the total optical length TTL of the optical lens is less than 6.0mm, and the maximum field angle FOV of the optical lens is more than or equal to 150 degrees. The optical lens of the invention adopts six lenses with specific refractive power, and adopts specific surface shapes and matching thereof, so that the lens spans into the line of the fisheye lens.

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

1<ET1/TC1<4.1；（1）

where TC1 denotes the center thickness of the first lens and ET1 denotes the edge thickness of the first lens. The optical system meets the conditional expression (1), so that the light rays entering the optical system with a large field angle are diffused, the incident angle of the diaphragm surface is reduced, the trend of the light rays tends to be smooth, and the difficulty of aberration correction is reduced.

0mm<SAG12-SAG11<0.84mm；（2）

where SGA11 denotes the edge rise of the object-side surface of the first lens, and SAG12 denotes the edge rise of the image-side surface of the first lens. Satisfying the conditional expression (2), the coma aberration of the system can be reduced, and the view field angle of the system can be increased.

0.89<f3/f<2.88；（3）

where f3 denotes a focal length of the third lens, and f denotes a focal length of the optical lens. Satisfying the conditional expression (3), the third lens has a larger positive focal power, and the third lens mainly contributes to the correction of spherical aberration, thereby being beneficial to shortening the length of the lens and realizing small volume of the lens.

1.1<f₁₂₃/f<1.97；（4）

wherein f is₁₂₃Denotes a combined focal length of the first lens, the second lens, and the third lens, and f denotes a focal length of the optical lens. The condition formula (4) is satisfied, the optical power of the first lens, the second lens and the third lens can be reasonably distributed, the trend of ray turning is slowed down, the correction of high-order aberration is reduced, and the difficulty of the correction of the integral aberration of the lens is reduced.

-0.44mm<SAG42-SAG41<-0.12mm；（5）

where SAG41 represents the edge rise of the object-side surface of the fourth lens, and SAG42 represents the edge rise of the image-side surface of the fourth lens. And the conditional expression (5) is satisfied, the optical path difference of the positive and negative TONGs is increased, the coma of the system is balanced, and the resolving power is improved.

Nd3≥1.54；（6）

Vd3≥55.9；（7）

where Nd3 denotes a refractive index of a material of the third lens, and Vd3 denotes an abbe number of the third lens. And conditional expressions (6) and (7) are satisfied, so that chromatic aberration correction of short-wave wavelength is facilitated.

0<R62/SAG62<9.28；（8）

where R62 denotes a radius of curvature of the image-side surface of the sixth lens, and SAG62 denotes an edge rise of the image-side surface of the sixth lens. The condition formula (8) is satisfied, the image quality of the off-axis field of view can be improved, the off-axis spherical aberration is reduced, the total length of the lens is reduced, and the small volume of the lens is realized.

0mm<SAG11<0.477mm；（9）

where SGA11 denotes the edge rise of the object side of the first lens. The condition formula (9) is satisfied, the object side surface of the first lens is ensured not to protrude out of the lens barrel, and the lens can be effectively prevented from being scratched in the using process.

In some embodiments, the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element are all plastic aspheric lenses. Each lens adopts an aspheric lens, so that the lens has better imaging quality, and the structure of the lens is more compact, thereby having smaller volume.

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

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

，

wherein z is the distance rise from the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis direction, c is the paraxial curvature radius 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 sequentially includes, from an object side to an image plane along an optical axis: a first lens L1, a second lens L2, a third lens L3, a stop ST, a fourth lens L4, a fifth lens L5, a sixth lens L6, and an infrared filter G1.

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

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

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

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

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

the sixth lens element L6 is an M-lens element with negative power, and its object-side surface S11 is convex at the paraxial region and its image-side surface S12 is concave at the paraxial region.

The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the sixth lens L6 are all plastic aspheric lenses. It should be noted that, in other embodiments, the first lens L1 to the sixth lens L6 may be all glass lenses, or may be a combination of plastic lenses and glass lenses.

The first embodiment of the present application provides an optical lens 100 with relevant parameters of each lens shown in table 1.

TABLE 1

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

TABLE 2

Referring to fig. 2, fig. 3 and fig. 4, a field curvature graph, an on-axis point-spherical aberration graph and a vertical axis aberration graph of the optical lens 100 are respectively shown.

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). As can be seen from fig. 2, the field curvature of the meridional image plane and the sagittal image plane is controlled within ± 0.3 mm.

The on-axis point spherical aberration curve of fig. 3 represents the aberration on the optical axis at the imaging plane. In fig. 3, the horizontal axis represents a sphere value (unit: mm) and the vertical axis represents a normalized angle of view. As can be seen from FIG. 3, the shift amount of the on-axis point spherical aberration is controlled within + -0.05 mm, which shows that the optical lens 100 can effectively correct the aberration of the fringe field and the secondary spectrum of the entire image plane.

The vertical axis chromatic aberration curve of fig. 4 shows chromatic aberration at different image heights on the image forming surface for the longest wavelength and the shortest wavelength. In fig. 4, the horizontal axis represents the homeotropic color difference (unit: um) 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 are controlled within ± 16.0um, which indicates that the vertical chromatic aberration of the optical lens 100 is well corrected.

Second embodiment

Referring to fig. 5, a schematic structural diagram of an optical lens 200 provided in the present embodiment is shown, where the optical lens 200 in the present embodiment has a structure substantially the same as that of the optical lens 100 in the first embodiment, and the difference is that: the sixth lens is a meniscus lens, and the curvature radius and material selection of each lens are different.

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

TABLE 3

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

TABLE 4

Referring to fig. 6, 7 and 8, a field curvature graph, an on-axis point spherical aberration graph and a vertical axis chromatic aberration graph of the optical lens 200 are respectively shown.

The field curvature curve of fig. 6 indicates the degree of curvature of the meridional image plane and the sagittal image plane. As can be seen from fig. 6, the field curvature of the meridional image plane and the sagittal image plane is controlled within ± 0.05mm, which indicates that the field curvature correction of the optical lens 200 is good.

The on-axis point spherical aberration curve of fig. 7 represents the aberration on the optical axis at the imaging plane. As can be seen from fig. 7, the offset of the on-axis point spherical aberration is controlled within ± 0.05mm, which shows that the optical lens 200 can effectively correct the aberration of the fringe field and the secondary spectrum of the entire image plane.

The vertical axis chromatic aberration curve of fig. 8 shows chromatic aberration at different image heights on the image forming surface for the longest wavelength and the shortest wavelength. As can be seen from fig. 8, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ± 2.0um, which indicates that the vertical chromatic aberration of the optical lens 200 is well corrected.

Third embodiment

Referring to fig. 9, a schematic structural diagram of an optical lens 300 according to the present embodiment is shown, where the structure of the optical lens 300 in the present embodiment is substantially the same as that of the optical lens 100 in the first embodiment, except that: in the present embodiment, the object-side surface S7 of the fourth lens element L4 of the optical mirror 300 is convex, and the curvature radius and material selection of each lens element are different.

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

TABLE 5

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

TABLE 6

Referring to fig. 10, 11 and 12, a field curvature graph, an on-axis point spherical aberration graph and a vertical axis chromatic aberration graph of the optical lens 300 are respectively shown.

The field curvature curve of fig. 10 indicates the degree of curvature of the meridional image plane and the sagittal image plane. As can be seen from fig. 10, the field curvature of the meridional image plane and the sagittal image plane is controlled within ± 0.05mm, which indicates that the field curvature correction of the optical lens 300 is good.

The on-axis point spherical aberration curve of fig. 11 represents the aberration on the optical axis at the imaging plane. As can be seen from fig. 11, the offset of the on-axis point spherical aberration is controlled within ± 0.01mm, which shows that the optical lens 300 can effectively correct the aberration of the fringe field and the secondary spectrum of the entire image plane.

The vertical axis chromatic aberration curve of fig. 12 shows chromatic aberration at different image heights on the image forming surface for the longest wavelength and the shortest wavelength. As can be seen from fig. 12, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ± 2.0um, which indicates that the vertical chromatic aberration of the optical lens 300 is well corrected.

Fourth embodiment

Referring to fig. 13, a schematic structural diagram of an optical lens 400 provided in the present embodiment is shown, where the optical lens 400 in the present embodiment has a structure substantially the same as that of the optical lens 100 in the first embodiment, except that: the sixth lens element L6 of the optical lens assembly 400 in this embodiment is a meniscus lens element with a concave surface facing the image plane, and the curvature radius and material selection of each lens element are different.

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

TABLE 7

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

TABLE 8

Referring to fig. 14, 15 and 16, a field curvature graph, an on-axis point spherical aberration graph and a vertical axis chromatic aberration graph of the optical lens 400 are respectively shown.

The field curvature curve of fig. 14 indicates the degree of curvature of the meridional image plane and the sagittal image plane. As can be seen from fig. 14, the field curvature of the meridional image plane and the sagittal image plane is controlled within ± 0.05mm, which indicates that the field curvature correction of the optical lens 400 is good.

The on-axis point spherical aberration curve of fig. 15 represents the aberration on the optical axis at the imaging plane. As can be seen from fig. 15, the offset of the on-axis point spherical aberration is controlled within ± 0.01mm, which shows that the optical lens 400 can effectively correct the aberration of the fringe field and the secondary spectrum of the entire image plane.

The vertical axis chromatic aberration curve in fig. 16 shows chromatic aberration at different image heights on the image forming surface for the longest wavelength and the shortest wavelength. As can be seen from fig. 16, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ± 6.0um, which indicates that the vertical chromatic aberration of the optical lens 400 is well corrected.

Referring to table 9, table 9 shows the optical characteristics corresponding to the four embodiments, which mainly include the focal length F, F #, total optical length TTL, and viewing angle 2 θ, and the values corresponding to each conditional expression.

TABLE 9

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

(1) the lens adopts six lens combinations with specific refractive power and specific surface shapes and matching thereof, and has a more compact structure while meeting the requirement of wide visual angle, thereby better realizing the miniaturization of the lens and the balance of the wide visual angle.

(2) In addition, the optical lens designed by the method enhances the depth and space of an imaging picture and has better imaging quality.

Fifth embodiment

As shown in fig. 17, a schematic structural diagram of an imaging apparatus 500 is provided for a fifth embodiment of the present invention, where the imaging apparatus 500 includes 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 terminal device loaded with the optical lens, and the terminal device may be, for example, a terminal device such as a smart phone, a smart tablet, a smart reader, or the like.

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 shall 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: the optical lens comprises a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens and a sixth lens, wherein the number of the lenses with focal power in the optical lens is six;

the first lens has negative 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, and the image side surface of the second lens is a concave surface;

the third lens has positive focal power, and both the object-side surface and the image-side surface of the third lens are convex surfaces;

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

the fifth lens element has a negative optical power, the fifth lens element has a concave object-side surface and a convex image-side surface at a paraxial region;

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

the total optical length TTL of the optical lens is less than 6.0mm, and the maximum field angle FOV of the optical lens is more than or equal to 150 degrees;

the optical lens satisfies the following conditional expression: 0< R62/SAG62< 9.28;

wherein R62 denotes a radius of curvature of an image-side surface of the sixth lens, and SAG62 denotes an edge rise of the image-side surface of the sixth lens.

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

1< ET1/TC1<4.1；

wherein TC1 represents the center thickness of the first lens and ET1 represents the edge thickness of the first lens.

3. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression: 0mm < SAG12-SAG11<0.84 mm;

wherein SAG11 represents an edge rise of an object-side surface of the first lens and SAG12 represents an edge rise of an image-side surface of the first lens.

4. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression: 0.89< f3/f < 2.88;

where f3 denotes a focal length of the third lens, and f denotes a focal length of the optical lens.

5. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression: 1.1<f₁₂₃/f<1.97；

Wherein f is₁₂₃Denotes a combined focal length of the first lens, the second lens, and the third lens, and f denotes a focal length of the optical lens.

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

-0.44mm<SAG42-SAG41<-0.12mm；

wherein SAG41 represents an edge rise of an object-side surface of the fourth lens and SAG42 represents an edge rise of an image-side surface of the fourth lens.

7. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression: nd3 is more than or equal to 1.54; vd3 is more than or equal to 55.95;

wherein Vd3 denotes an abbe number of the third lens, and Nd3 denotes a material refractive index of the third lens.

8. An optical lens according to claim 1, characterized in that the optical lens satisfies the following conditional expression: 0mm < SAG11<0.477 mm;

wherein SGA11 denotes an edge rise of an object side surface of the first lens.

9. An optical lens according to claim 1, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are all plastic aspheric lenses.

10. An imaging apparatus comprising the optical lens according to any one of claims 1 to 9 and an imaging element for converting an optical image formed by the optical lens into an electric signal.