CN108663772B

CN108663772B - Optical lens and imaging apparatus

Info

Publication number: CN108663772B
Application number: CN201710207355.1A
Authority: CN
Inventors: 王东方; 姚波; 谢前森
Original assignee: Ningbo Sunny Automotive Optech Co Ltd
Current assignee: Ningbo Sunny Automotive Optech Co Ltd
Priority date: 2017-03-31
Filing date: 2017-03-31
Publication date: 2022-07-05
Anticipated expiration: 2037-03-31
Also published as: CN108663772A

Abstract

The invention provides an optical lens and an imaging apparatus. The optical lens includes, in order from an object side to an image side: the first lens is a meniscus lens with 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, and the image side surface of the second lens is a concave surface; a third lens element which is a biconvex lens element having positive refractive power, wherein the object-side surface of the third lens element is convex, the image-side surface of the third lens element is convex, and the absolute value of the ratio of the radius of the object-side surface to the radius of the image-side surface is greater than or equal to 18; a fourth lens; a fifth lens cemented with the fourth lens; and a sixth lens having a positive power. With the optical lens and the imaging apparatus according to the present invention, it is possible to obtain a high resolution while keeping the optical lens compact.

Description

Optical lens and imaging apparatus

Technical Field

The present invention relates to the field of optical lenses and imaging apparatuses, and particularly to an optical lens and an imaging apparatus capable of obtaining a high resolution while keeping the lens compact.

Background

Imaging apparatuses, such as camera-mounted mobile apparatuses and digital still cameras, using, for example, a Charge Coupled Device (CCD) and a Complementary Metal Oxide Semiconductor (CMOS) as a solid-state imaging element have been well known.

With the development of science and technology, the requirements for the resolution of optical lenses are higher and higher, and the requirements are continuously raised from the original million pixels to the direction of ten million pixels, and high-pixel lenses are more and more popular.

In addition, with the popularization of mobile devices, there is a need to apply imaging devices of increasingly small sizes, such as those applied to mobile phones, for which the demand for small sizes is very high.

In general, the resolution can be improved by increasing the number of lenses in the optical lens, but the size and weight of the optical lens are increased accordingly, which is disadvantageous to the miniaturization of the optical lens and causes an increase in cost.

At present, a wide-angle optical lens with mega pixels and more generally adopts 6 lenses, although the resolution is obviously improved compared with an optical lens with 5 lenses, the requirement for miniaturization is more prominent due to the increase of the number of the lenses.

Conventionally, in order to meet the demand for miniaturization of an optical lens, a scheme of compressing the optical total length of the lens is generally adopted, but the resolution is significantly affected. Meanwhile, the imaging quality can be improved by additionally adopting the aspheric lens, but the cost of the glass aspheric lens is higher, and the temperature performance of the lens is reduced due to excessive use of the plastic aspheric lens.

In particular, for a lens that operates in an outdoor environment, such as a monitor lens or a vehicle-mounted lens, on the one hand, the operating environment is variable, and it is necessary to maintain perfect resolution no matter in hot and high-temperature days or in cold and rainy and snowy days, and on the other hand, the installation space is limited. Therefore, how to obtain as high imaging quality as possible while ensuring miniaturization of the optical lens is a problem to be urgently solved.

Accordingly, there is a need for improved optical lenses and imaging devices.

Disclosure of Invention

An object of the present invention is to provide a novel and improved optical lens and imaging apparatus capable of achieving a high resolution while keeping the lens compact, in view of the above-mentioned drawbacks and disadvantages of the prior art.

An object of the present invention is to provide an optical lens and an imaging apparatus which contribute to obtaining a high resolving power while keeping the optical lens compact by the shape and power setting of a third lens in the optical lens.

An object of the present invention is to provide an optical lens and an imaging apparatus, which can reduce the rear port diameter/size of the optical lens by having a positive film in front and a negative film in rear of a fourth lens and a fifth lens cemented to each other, and by converging light rays by the positive film.

An object of the present invention is to provide an optical lens and an imaging apparatus, in which the third lens is a glass lens, which is beneficial to thermal compensation, and further the third lens is an aspheric glass lens, which can further improve the resolution.

An object of the present invention is to provide an optical lens and an imaging apparatus which can significantly shorten the optical length of the optical lens and improve the resolving power while ensuring the miniaturization of the optical lens by optimally setting the shapes of respective lenses and reasonably distributing the powers of the respective lenses.

An object of the present invention is to provide an optical lens and an imaging apparatus, which are advantageous to effectively converge light entering an optical system and reduce the lens aperture of the optical system by locating a diaphragm between a third lens and a fourth lens.

According to an aspect of the present invention, there is provided an optical lens including, in order from an object side to an image side: the first lens is a meniscus lens with 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, and the image side surface of the second lens is a concave surface; a third lens element which is a biconvex lens element having a positive refractive power, wherein an object-side surface of the third lens element is a convex surface, an image-side surface of the third lens element is a convex surface, and an absolute value of a ratio of a radius of the object-side surface to a radius of the image-side surface is greater than or equal to 18; a fourth lens; a fifth lens cemented with the fourth lens; and a sixth lens having a positive power.

In the above optical lens assembly, the fourth lens element is a biconvex lens element with positive refractive power, and has a convex object-side surface and a convex image-side surface; and the fifth lens is a meniscus lens with negative focal power, the object side surface of the fifth lens is a concave surface, and the image side surface of the fifth lens is a convex surface.

In the above optical lens system, the second lens element is a meniscus lens element, and the object side surface thereof is a convex surface.

In the above optical lens assembly, the second lens element is a biconcave lens element, and the object-side surface of the second lens element is a concave surface.

In the above optical lens system, an object-side surface of the sixth lens element is a convex surface, and an image-side surface of the sixth lens element is a convex surface.

In the above optical lens, four or more lenses of the first lens to the sixth lens are aspherical lenses.

In the above optical lens, the second lens, the fourth lens, the fifth lens, and the sixth lens are aspherical lenses.

In the above optical lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are aspherical lenses.

In the above optical lens, the third lens is a glass lens.

In the above optical lens, the third lens is a glass aspherical lens.

In the above optical lens, the optical lens further includes a diaphragm, the diaphragm being located between the third lens and the fourth lens.

In the above optical lens, the first lens to the sixth lens satisfy the following conditional expression (1):

F3/F≤5.5 (1)

where F3 is the focal length of the third lens, and F is the entire set of focal length values of the optical lens.

In the above optical lens, the first lens to the sixth lens satisfy the following conditional expression (2):

TTL/F≤14.5 (2)

wherein, F is the whole group focal length value of the optical lens, and TTL is the optical length of the optical lens.

According to another aspect of the present invention, there is provided an imaging apparatus including the optical lens described above and an imaging element for converting an optical image formed by the optical lens into an electrical signal.

The optical lens and the imaging apparatus provided by the present invention contribute to obtaining high resolution while keeping the optical lens miniaturized by the shape and power setting of the third lens in the optical lens.

Further, the optical lens and the imaging device provided by the invention can remarkably shorten the optical length of the optical lens by optimally setting the shape of each lens and reasonably distributing the focal power of each lens, and improve the resolution while ensuring the miniaturization of the optical lens.

Drawings

Fig. 1 illustrates a lens configuration of an optical lens according to a first embodiment of the present invention;

fig. 2 illustrates a lens configuration of an optical lens according to a second embodiment of the present invention;

fig. 3 is a schematic block diagram of an image forming apparatus according to an embodiment of the present invention.

Detailed Description

The following description is presented to disclose the invention so as to enable any person skilled in the art to practice the invention. The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art. The basic principles of the invention, as defined in the following description, may be applied to other embodiments, variations, modifications, equivalents, and other technical solutions without departing from the spirit and scope of the invention.

The terms and words used in the following specification and claims are not limited to the literal meanings, but are used only by the inventors to enable a clear and consistent understanding of the invention. Accordingly, it will be apparent to those skilled in the art that the following descriptions of the various embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

The terminology used herein is for the purpose of describing various embodiments only and is not intended to be limiting. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, numbers, steps, operations, components, elements, or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, elements, or groups thereof.

Terms used herein, including technical and scientific terms, have the same meaning as terms commonly understood by one of ordinary skill in the art, unless otherwise defined. It will be understood that terms defined in commonly used dictionaries have meanings that are consistent with their meanings in the prior art.

The invention is described in further detail below with reference to the following figures and detailed description:

[ arrangement of optical lens ]

According to the optical lens of the embodiment of the present invention, the optical lens includes, in order from an object side to an image side: the first lens is a meniscus lens with negative focal power, and 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 is a lens with negative focal power, and the image side surface of the second lens is a concave surface; the third lens is a biconvex lens with positive focal power, the object side surface of the third lens is a convex surface, the image side surface of the third lens is a convex surface, and the absolute value of the ratio of the radius of the object side surface to the radius of the image side surface is greater than or equal to 18; a fourth lens; a fifth lens cemented with the fourth lens; the sixth lens element is a biconvex lens element with positive focal power, and has a convex object-side surface and a convex image-side surface.

In the optical lens according to an embodiment of the present invention, it is helpful to obtain a high resolving power while keeping the optical lens compact by the shape and power setting of the third lens in the optical lens, which will be described in further detail later.

In the above optical lens, preferably, the fourth lens element is a biconvex lens element having a positive refractive power, and has a convex object-side surface and a convex image-side surface. In addition, the fifth lens element is a meniscus lens element with negative power, and has a concave object-side surface and a convex image-side surface. Thus, the positive film is arranged in front of the negative film when viewed from the incident direction of the light, and the negative film is arranged behind the positive film, so that the light can be converged by the positive film, and the rear port diameter/size of the optical lens is reduced.

In the above optical lens, the second lens is a meniscus lens having a negative power or a biconcave lens having a negative power. That is, the image-side surface of the second lens element is concave, and the object-side surface can be convex or concave.

In the above optical lens, preferably, four or more lenses of the first lens to the sixth lens are aspherical lenses.

In the above optical lens, preferably, the third lens is a glass lens, and more preferably, the third lens is an aspherical glass lens. When the third lens is a glass lens, thermal compensation is facilitated. In addition, when the third lens is an aspherical glass lens, the resolution can be further improved. Here, it may be understood by those skilled in the art that, in the optical lens according to the embodiment of the present invention, the third lens is not limited to only a glass lens or an aspherical glass lens. For example, the third lens may also be a plastic aspherical lens, which may achieve high resolution and low cost, but has poor temperature performance. Therefore, in practical applications, the mirror shape and material of the third lens can be determined according to specific requirements.

Preferably, in the above optical lens, the first lens to the sixth lens satisfy the following conditional expressions (1) and (2):

F3/F≤5.5 (1)

TTL/F≤14.5 (2)

where F3 is the focal length of the third lens, F is the entire group focal length value of the optical lens, and TTL is the optical length of the optical lens, i.e., the distance from the object-side outermost point of the first lens to the imaging focal plane.

In addition, in the above optical lens, the third lens satisfies the following conditional expression (3):

i R5/R6 ≧ 18 (3)

Where R5 is the radius of the object-side surface of the third lens, and R6 is the radius of the image-side surface of the third lens. R5/R6 represents the absolute value of the ratio of the radius of the object side to the radius of the image side of the third lens.

Therefore, in the optical lens according to the embodiment of the present invention, since the biconvex shape of the third lens, the ratio of the object side radius to the image side radius, and the positive power setting contribute to forming a short TTL, a miniaturized optical lens is obtained. Therefore, in the optical lens according to the embodiment of the present invention, the mirror shape and material of the third lens are not limited.

Here, it can be understood by those skilled in the art that, in the optical lens according to the embodiment of the present invention, in addition to the shape and power setting of the third lens, by optimally setting the shape of each lens and reasonably distributing the power of each lens, it is possible to significantly shorten the TTL and improve the resolution while ensuring the miniaturization of the optical lens.

In the above optical lens, a stop is further included. Preferably, the diaphragm is located between the third lens and the fourth lens, so that light rays entering the optical system are effectively converged, and the aperture of a lens of the optical system is reduced. Of course, the skilled person will understand that the diaphragm may also be located between any other discrete lenses.

In addition, in the case where the optical lens according to the embodiment of the present invention includes the diaphragm, it is preferable to dispose the fourth lens and the fifth lens cemented to each other at positions close to the diaphragm in consideration of the balance of system aberrations and the rationality of the structure.

Next, the structures and functions of the first to sixth lenses in the optical lens according to the embodiment of the present invention will be further described in detail.

In the optical lens system according to the embodiment of the invention, the first lens element has a meniscus shape convex toward the object side, and the object side surface of the first lens element is convex and the image side surface of the first lens element is concave. The convex surface of the first lens is curved toward the object side, so that the incident angle of the incident light on the attack surface is small, and more light can be collected to enter the optical system of the embodiment of the invention. In addition, when applied to an on-vehicle front view lens, the on-vehicle front view lens is used in an outdoor environment, and is subject to severe weather such as rain and snow, for example. The convexity is advantageous for accommodating outdoor use of the on-vehicle front-view lens, for example, when in an environment such as rainy weather, the convexity can facilitate the sliding off of water droplets, thereby reducing the impact on imaging.

In addition, the first lens may be a spherical glass lens or an aspherical glass lens. When the first lens is a spherical glass lens, the cost of the optical lens can be reduced. When the first lens is an aspheric glass lens, the aperture of the front end of the lens can be reduced, the whole volume of the lens can be reduced, and the resolution power can be further improved.

In the optical lens system according to the embodiment of the invention, the second lens element is a meniscus lens element or a biconcave lens element with a concave image-side surface, and the object-side surface of the second lens element may be a convex surface or a concave surface. Because the first lens of the optical lens is a divergent lens, the light rays collected by the first lens are compressed by the configuration of the second lens, so that the trend of the light rays is relatively gentle, and the light rays are smoothly transited to the rear.

In the optical lens barrel according to the embodiment of the invention, the third lens element is a biconvex lens element, and the object-side surface of the third lens element is a convex surface and the image-side surface of the third lens element is a convex surface. The third lens is a convergent lens, so that the divergent light rays can smoothly enter the rear part. In addition, the third lens can balance and compensate spherical aberration and positional chromatic aberration introduced by the first lens and the second lens. In addition, as described above, the shape and focal power of the third lens are set more reasonably, which is beneficial to shortening the total length of the optical system and maintaining the high resolution of the whole optical lens.

In the optical lens barrel according to the embodiment of the present invention, a stop is located between the third lens and the fourth and fifth lenses cemented with each other, for converging front and rear light rays, shortening the total length of the optical system, and reducing the aperture of the front and rear lens groups.

In the optical lens according to the embodiment of the present invention, the fourth lens and the fifth lens cemented to each other can correct chromatic aberration by themselves, reduce tolerance sensitivity, and also can leave a part of chromatic aberration to balance chromatic aberration of the system. In addition, when viewed from the light incidence direction, the positive film with positive focal power is in front, the negative film with negative focal power is behind, the front light can be further converged and then transited to the rear, and the rear port diameter/size of the optical lens is reduced, so that the total length of the system is further reduced.

In the optical lens barrel according to the embodiment of the invention, the sixth lens element is a biconvex lens element, and the object-side surface of the sixth lens element is a convex surface and the image-side surface of the sixth lens element is a convex surface. Thus, the sixth lens is a converging lens, so that the light rays are converged. In addition, the sixth lens is preferably an aspheric lens, which can satisfy a system with a small FNO, such as FNO ≦ 2, while reducing the optical path length of the peripheral light to the imaging surface. Moreover, by using the aspheric surface, the sixth lens can perform a good correction function on the off-axis point aberration, and optimize the optical performance such as distortion, CRA and the like.

Here, it can be understood by those skilled in the art that the optical lens according to the embodiment of the present invention can be applied to other lens applications requiring light weight, miniaturization, low cost, and high resolution in addition to the vehicle-mounted front view lens, and the embodiment of the present invention is not intended to limit it in any way.

[ numerical example of optical lens ]

Hereinafter, specific embodiments and numerical examples of an optical lens according to an embodiment of the present invention, in which specific numerical values are applied to the respective embodiments, will be described with reference to the drawings and tables.

Some of the lenses used in the embodiments have an aspherical lens surface, and the aspherical surface shape is represented by the following expression (3):

wherein, z (h) is a distance rise from the vertex of the aspherical surface when the aspherical surface is at a position of height h in the optical axis direction.

c is 1/r, r represents the curvature radius of the lens surface, k is a cone coefficient, A, B, C, D and E are high-order aspheric coefficients, and E in the coefficients represents scientific notation, such as E-05 represents 10^-5。

In addition, Nd denotes a refractive index, and Vd denotes an abbe number.

First embodiment

As shown in fig. 1, the optical lens according to the first embodiment of the present invention includes, in order from an object side to an image side: a meniscus-shaped first lens L1 having a negative power, having a convex object-side first surface S1 and a concave image-side second surface S2; a meniscus-shaped second lens L2 having a negative power, having a convex object-side first surface S3 and a concave image-side second surface S4; a biconvex third lens L3 having positive optical power and having a first surface S5 convex to the object side and a second surface S6 convex to the image side; a diaphragm STO; a fourth lens L4 and a fifth lens L5 cemented with each other, in which the fourth lens L4 is a biconvex shape having a positive power, has a first surface S8 convex to the object side and a second surface S9 convex to the image side, the fifth lens L5 is a meniscus shape having a negative power, has a first surface S9 concave to the object side and a second surface S10 convex to the image side; a biconvex sixth lens L6 having positive optical power and having a first surface S11 convex to the object side and a second surface S12 convex to the image side; a planar lens L7 having a first surface S13 facing the object side and a second surface S14 facing the image side, typically a color filter; a planar lens L8 having a first surface S15 facing the object side and a second surface S16 facing the image side, typically a protective glass, for protecting the image plane; l9 has an image plane S17, typically a chip.

The lens data of the above lenses are shown in table 1 below:

[ TABLE 1 ]

Surface of	Radius of	Thickness of	Nd	Vd
					1	10.7223	0.6791	1.77	49.61
2	2.9302	1.8176
					3	7.8394	0.6433	1.51	56.29
4	0.9525	1.0906
					5	67.1026	1.5049	1.87	21.00
6	-3.6055	0.4476
					STO	Infinite number of elements	0.1613
8	2.4079	1.6441	1.53	56.07
					9	-0.4760	0.4289	1.64	23.53
10	-23.3520	0.2262
					11	2.3746	0.9293	1.53	56.07
12	-3.5678	0.0707
					13	Infinite number of elements	0.5500	1.52	64.21
14	Infinite number of elements	0.3182
					15	Infinite number of elements	0.4000	1.52	64.21
16	Infinite number of elements	0.9748
					Image plane	Unlimited in size

The conic coefficients k and the high-order aspherical coefficients A, B, C, D and E of the surfaces S3 and S4 of the second lens, the surfaces S8, S9 and S10 of the fourth lens and the fifth lens, and the surfaces S11 and S12 of the sixth lens are shown in table 2 below.

[ TABLE 2 ]

Surface of

k

A

B

C

D

E

3

-108.0012

5.5657E-04

-2.4980E-03

4.0301E-04

-2.6131E-05

2.1896E-07

4

-1.2815

3.0237E-02

9.5489E-03

4.1107E-04

-1.1806E-03

2.5666E-03

8

-1.6342

3.0154E-02

-2.3321E-02

1.1346E-01

-1.5091E-01

7.2846E-02

9

-1.7489

-1.9480E-01

6.5092E-02

-5.9786E-01

5.9121E-01

-1.7400E-01

10

210.0008

-7.8836E-03

-1.7191E-04

7.0441E-04

-1.1806E-03

3.4906E-03

11

-10.5744

-7.0932E-03

7.6009E-03

-9.0824E-04

1.2435E-03

-1.5386E-05

12

0.3704

1.1610E-02

2.6983E-03

1.0071E-02

-3.0290E-04

8.4235E-04

In the optical lens according to the first embodiment of the present invention, the focal length F3 of the third lens, the entire group focal length value F of the optical lens, and the optical length TTL of the optical lens and the relationship therebetween, and the radius R5 of the surface S5 of the third lens, the radius R6 of the surface S6 and the relationship therebetween are as shown in table 3 below.

[ TABLE 3 ]

F3	3.933042
		F	1.1
TTL	11.8864
		R5	67.102601
R6	-3.60546
		F3/F	3.57549
TTL/F	10.805818
		I R5/R6I	18.611384

As can be seen from table 3 above, the optical lens according to the first embodiment of the present invention satisfies the aforementioned conditional expressions (1), (2), and (3), thereby obtaining a high resolving power while keeping the optical lens miniaturized.

Second embodiment

As shown in fig. 2, the optical lens according to the second embodiment of the present invention, in order from an object side to an image side, comprises: a meniscus-shaped first lens L1 having a negative power, having a first surface S1 convex toward the object side and a second surface S2 concave toward the image side; a biconcave second lens L2 having a negative power, having a concave object-side first surface S3 and a concave image-side second surface S4; a biconvex third lens L3 having positive optical power, having a first surface S5 convex to the object side and a second surface S6 convex to the image side; a diaphragm STO; a fourth lens L4 and a fifth lens L5 cemented with each other, in which the fourth lens L4 is a biconvex shape having a positive power, has a first surface S8 convex to the object side and a second surface S9 convex to the image side, the fifth lens L5 is a meniscus shape having a negative power, has a first surface S9 concave to the object side and a second surface S10 convex to the image side; a biconvex sixth lens L6 having positive optical power and having a first surface S11 convex to the object side and a second surface S12 convex to the image side; a planar lens L7 having a first surface S13 facing the object side and a second surface S14 facing the image side, typically a color filter; a planar lens L8 having a first surface S15 facing the object side and a second surface S16 facing the image side, typically a protective glass, for protecting the image plane; l9 has an image plane S17, typically a chip.

The lens data for the above lenses are shown in table 4 below:

[ TABLE 4 ]

Surface of	Radius of	Thickness of	Nd	Vd
					1	8.8170	0.8928	1.77	49.61
2	2.4919	2.1739
					3	-22.7278	0.7988	1.51	56.29
4	1.4954	0.9433
					5	87.6390	2.1670	1.85	23.79
6	-4.6134	0.2203
					STO	Infinite number of elements	0.6000
8	3.1639	1.9545	1.51	64.00
					9	-2.0488	0.5639	1.70	30.00
10	-29.5429	0.1931
					11	3.1041	1.2217	1.53	56.07
12	-4.4053	0.0930
					13	Infinite number of elements	0.5500	1.52	64.21
14	Infinite number of elements	0.4183
					15	Infinite number of elements	0.4000	1.52	64.21
16	Unlimited in size	1.4545
					Image plane	Unlimited in size

The conic coefficients k and the high-order aspherical coefficients A, B, C, D and E of the surfaces S3 and S4 of the second lens, the surfaces S8, S9 and S10 of the fourth lens and the fifth lens, and the surfaces S11 and S12 of the sixth lens are shown in table 5 below.

[ TABLE 5 ]

Surface of

k

A

B

C

D

E

3

-1378.2800

-5.4682E-04

-6.5770E-04

5.9247E-05

-1.8477E-06

1.6793E-06

4

-0.8071

2.4565E-02

2.9730E-04

-6.1831E-04

-1.3787E-03

4.5744E-04

8

-1.0325

1.1537E-02

-4.5230E-03

1.8810E-03

-1.1812E-02

2.5662E-03

9

-2.7456

-8.6273E-02

1.3290E-02

-9.2073E-02

4.7318E-02

-1.0734E-02

10

186.4813

-4.0445E-03

-5.6146E-05

1.6553E-04

-1.0591E-04

1.3281E-04

11

-11.2991

-2.3729E-03

2.0330E-03

-1.5992E-04

1.1465E-04

-3.7243E-06

12

0.3885

5.2120E-03

3.1236E-04

1.4552E-03

-2.4718E-04

4.5558E-05

In the optical lens according to the second embodiment of the present invention, the focal length F3 of the third lens, the entire group focal length value F of the optical lens, and the optical length TTL of the optical lens and the relationship therebetween, and the radius R5 of the surface S5 of the third lens, the radius R6 of the surface S6 and the relationship therebetween are as shown in table 6 below.

[ TABLE 6 ]

F3	5.187112
		F	1.09765
TTL	14.645
		R5	87.63901
R6	-4.613391
		F3/F	4.725652075
TTL/F	13.34214003
		I R5/R6I	18.99665777

As can be seen from table 6 above, the optical lens according to the second embodiment of the present invention satisfies the aforementioned conditional expressions (1), (2), and (3), thereby obtaining a high resolving power while keeping the optical lens miniaturized.

Here, it is understood by those skilled in the art that, although the third lens is a spherical lens in both the above first and second embodiments, the third lens may be an aspherical lens as described above.

In summary, in the optical lens according to the embodiment of the present invention, by the shape and power setting of the third lens in the optical lens, it is helpful to obtain a high resolving power while keeping the optical lens compact.

In the optical lens according to the embodiment of the present invention, by having the positive film in the fourth lens and the fifth lens cemented to each other in front and the negative film in back, the light can be converged by the positive film, reducing the rear port diameter/size of the optical lens.

In the optical lens according to the embodiment of the invention, the third lens is a glass lens, which is beneficial to thermal compensation, and the third lens is an aspheric glass lens, which can further improve the resolution.

In the optical lens according to the embodiment of the invention, by optimally setting the shapes of the lenses and reasonably distributing the focal powers of the lenses, the TTL can be remarkably shortened, and the resolving power is improved while the miniaturization of the optical lens is ensured.

In the optical lens according to the embodiment of the invention, the diaphragm is positioned between the third lens and the fourth lens, so that the light rays entering the optical system can be effectively converged, and the lens aperture of the optical system can be reduced.

In the optical lens according to the embodiment of the present invention, by disposing the fourth lens and the fifth lens cemented to each other at a position close to the stop, it is possible to contribute to balance of system aberrations and rationality of structure.

In addition, in the optical lens according to the embodiment of the invention, the object-side surface of the first lens is a convex surface, so that the incident angle of the incident light on the attack surface is small, which is beneficial to collecting more light. In addition, the convex surface of the object side surface of the first lens is beneficial to being suitable for outdoor use of the optical lens.

In addition, in the optical lens according to the embodiment of the invention, the first lens is a spherical glass lens, so that the cost of the optical lens can be reduced. Moreover, the first lens is an aspheric glass lens, so that the caliber of the front end of the lens can be reduced, the whole volume of the lens can be reduced, and the resolution can be further improved.

In addition, in the optical lens according to the embodiment of the invention, the second lens has negative focal power, so that the light collected by the first lens can be compressed by the configuration of the second lens, the trend of the light is relatively gentle, and the light can be smoothly transited to the rear.

In addition, in the optical lens according to the embodiment of the present invention, the third lens is a converging lens having positive refractive power, so that the divergent light rays smoothly enter the rear. And, the third lens can balance and compensate spherical aberration and positional aberration introduced by the first lens and the second lens.

In addition, in the optical lens according to the embodiment of the present invention, by the fourth lens and the fifth lens being cemented to each other, the fourth lens and the fifth lens themselves can correct chromatic aberration, reduce tolerance sensitivity, and also can leave a part of chromatic aberration to balance chromatic aberration of the system.

In addition, in the optical lens according to the embodiment of the present invention, the light rays are converged by the sixth lens being a converging lens having a positive power. Moreover, the sixth lens is an aspheric lens, so that a system with a small FNO can be met, the optical path of peripheral light reaching an imaging plane is reduced, good correction effect on axial-external point aberration can be achieved, and optical performances such as distortion and CRA (crazing-related interference) are optimized.

[ configuration of image Forming apparatus ]

According to another aspect of embodiments of the present invention, there is provided an imaging apparatus including an optical lens and an imaging element for converting an optical image formed by the optical lens into an electric signal, the optical lens including, in order from an object side to an image side: a first lens element having a negative refractive power and a meniscus shape, the first lens element having a convex object-side surface and a concave image-side surface; the second lens has negative focal power, and the image side surface of the second lens is a concave surface; a third lens element which is a biconvex lens element having a positive refractive power, wherein the object-side surface of the third lens element is convex, the image-side surface of the third lens element is convex, and the absolute value of the ratio of the radius of the object-side surface to the radius of the image-side surface is greater than or equal to 18; a fourth lens; a fifth lens cemented with the fourth lens; and a sixth lens having a positive power.

Fig. 3 is a schematic block diagram of an image forming apparatus according to an embodiment of the present invention. As shown in fig. 3, an imaging apparatus 100 according to an embodiment of the present invention includes an optical lens 101 and an imaging element 102. The optical lens 101 is used for capturing an optical image of a subject, and the imaging element 102 is used for converting the optical image captured by the optical lens 101 into an electrical signal.

In the optical lens assembly, the fourth lens element is a biconvex lens element with positive refractive power, and has a convex object-side surface and a convex image-side surface; and the fifth lens is a meniscus lens with negative power, the object side surface of the fifth lens is a concave surface, and the image side surface of the fifth lens is a convex surface.

In the above optical lens system, the second lens element is a meniscus lens element, and the object side surface thereof is convex.

In the above optical lens, the second lens is a biconcave lens whose object-side surface is concave.

In the optical lens assembly, an object-side surface of the sixth lens element is convex, and an image-side surface of the sixth lens element is convex.

In the above optical lens, the second lens, the fourth lens, the fifth lens and the sixth lens are aspheric lenses.

In the above optical lens assembly, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element are aspheric lens elements.

In the above optical lens, the third lens is a glass lens.

In the above optical lens, the third lens is a glass aspherical lens.

In the above optical lens, the optical lens further includes a diaphragm located between the third lens and the fourth lens.

F3/F≤5.5 (1)

wherein, F3 is the focal length of the third lens, and F is the whole focal length of the optical lens.

TTL/F≤14.5 (2)

Here, it can be understood by those skilled in the art that other details of the optical lens in the imaging apparatus according to the embodiment of the present invention are the same as those described above with respect to the optical lens according to the embodiment of the present invention, and the aforementioned numerical examples of the optical lens according to the first embodiment to the second embodiment of the present invention may be adopted, and thus, no trace is made to avoid redundancy.

The optical lens and the imaging apparatus according to the embodiments of the present invention contribute to obtaining a high resolving power while keeping the optical lens compact by the shape and power setting of the third lens in the optical lens.

Further, the optical lens and the imaging apparatus according to the embodiments of the present invention can significantly shorten TTL and improve resolution while ensuring miniaturization of the optical lens by optimally setting the shapes of the respective lenses and reasonably distributing the powers of the respective lenses.

According to the optical lens and the imaging device, the optical lens and the imaging device are provided with the fourth lens and the fifth lens which are glued with each other, the positive film is in front, the negative film is behind, light can be converged through the positive film, and the rear port diameter/size of the optical lens is reduced.

According to the optical lens and the imaging device provided by the embodiment of the invention, the third lens is the glass lens, so that the thermal compensation is facilitated, and the third lens is the aspheric glass lens, so that the resolution can be further improved.

According to the optical lens and the imaging device provided by the embodiment of the invention, the diaphragm is positioned between the third lens and the fourth lens, so that the light rays entering the optical system can be effectively converged, and the lens aperture of the optical system is reduced.

Further, the optical lens and the imaging apparatus according to the embodiment of the present invention contribute to balance of system aberrations and rationality of structure by disposing the fourth lens and the fifth lens cemented to each other at a position close to the diaphragm.

In the optical lens and the imaging apparatus according to the embodiments of the present invention, a lens having substantially no lens power may also be arranged. Therefore, in addition to the first to sixth lenses described above, additional lenses may be arranged. In this case, the optical lens and the imaging apparatus according to the embodiment of the present invention may be configured with six or more lenses, and these lenses include additional lenses arranged in addition to the above-described first to sixth lenses.

It will be appreciated by persons skilled in the art that the embodiments of the invention described above and shown in the drawings are given by way of example only and are not limiting of the invention. The objects of the invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.

Claims

1. An optical lens includes six lenses in order from an object side to an image side, the six lenses are respectively:

the first lens is a meniscus lens with 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, and the image side surface of the second lens is a concave surface;

the third lens is a biconvex lens with positive focal power, the object side surface of the third lens is a convex surface, the image side surface of the third lens is a convex surface, and the ratio of the radius R5 of the object side surface to the radius R6 of the image side surface satisfies: R5/R6 is less than or equal to-18;

the fourth lens is a biconvex lens with positive focal power, and the object side surface and the image side surface of the fourth lens are convex surfaces;

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

a sixth lens having a positive refractive power;

the first lens to the sixth lens satisfy the following conditional expression (1):

TTL/F≤14.5 （1）

the first lens to the sixth lens satisfy the following conditional expression (2):

4.725652075≤F3/F≤5.5 （2）

wherein F is a whole group focal length value of the optical lens, TTL is an optical length of the optical lens, and F3 is a focal length of the third lens.

2. An optical lens according to claim 1,

the second lens is a meniscus lens with a convex object-side surface.

3. An optical lens according to claim 1,

the second lens is a biconcave lens, and the object side surface of the second lens is a concave surface.

4. An optical lens according to claim 1, wherein four or more lenses of the first lens to the sixth lens are aspherical lenses.

5. An optical lens according to claim 4, characterized in that the second lens, the fourth lens, the fifth lens and the sixth lens are aspherical lenses.

6. An optical lens according to claim 4, wherein the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are aspherical lenses.

7. An optical lens according to claim 1, characterized in that the third lens is a glass lens.

8. An optical lens according to claim 1, characterized in that the third lens is a glass aspherical lens.

9. An optical lens according to any one of claims 1 to 8, characterized in that the optical lens further comprises an optical stop, which is located between the third lens and the fourth lens.

10. An imaging apparatus comprising the optical lens of claim 1 and an imaging element for converting an optical image formed by the optical lens into an electric signal.