CN110412730B - Optical lens - Google Patents

Abstract

The present application discloses an optical lens, which sequentially comprises, from an object side to an image side along an optical axis: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. The first lens can have negative focal power, and the object side surface of the first lens can be a convex surface, and the image side surface of the first lens can be a concave surface; the second lens can have negative focal power, and both the object side surface and the image side surface of the second lens can be concave; the third lens can have positive focal power, and both the object side surface and the image side surface of the third lens can be convex surfaces; and the fourth lens, the fifth lens and the sixth lens can be cemented to form a cemented triplet. According to the optical lens of the present application, at least one of advantageous effects of high pixel, miniaturization, low cost, low sensitivity, and the like can be achieved.

Description

Optical lens

Technical Field

The present application relates to an optical lens, and more particularly, to an optical lens including six lenses.

Background

With the rapid popularization of backing back views, automobile data recorders and the like in the field of automobiles, wide-angle lenses are required to have a wider field of view and clearer resolving power. The resolution of the lens can be generally improved by increasing the number of lenses, and the aberration can be corrected by using an aspherical surface. However, in order to improve the resolution, the overall length of the system is often sacrificed, which is contrary to the current miniaturization trend of the vehicle-mounted lens, and the cost is also greatly increased.

Therefore, it is necessary to design an optical lens that satisfies the performance of miniaturization, high pixel, low cost, low sensitivity, etc. so as to better meet the usage requirement of the vehicle-mounted environment.

Disclosure of Invention

The present application provides an optical lens that is adaptable for on-board installation and that overcomes, at least in part, at least one of the above-identified deficiencies in the prior art.

An aspect of the present application provides an optical lens that may include, in order from an object side to an image side along an optical axis: the lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. The first lens can have negative focal power, and the object side surface of the first lens can be a convex surface, and the image side surface of the first lens can be a concave surface; the second lens can have negative focal power, and both the object side surface and the image side surface of the second lens can be concave; the third lens can have positive focal power, and both the object side surface and the image side surface of the third lens can be convex surfaces; and the fourth lens, the fifth lens and the sixth lens can be cemented to form a cemented triplet.

In one embodiment, the fourth lens may have a positive optical power, and both the object-side surface and the image-side surface thereof may be convex.

In one embodiment, the fifth lens can have a negative power, and both the object-side surface and the image-side surface can be concave.

In one embodiment, the sixth lens element can have a positive optical power, and both the object-side surface and the image-side surface can be convex.

In one embodiment, at least three lenses in the optical lens may be aspheric lenses.

In one embodiment, the refractive index of the material of the first lens may be 1.7 or more.

In one embodiment, the conditional formula may be satisfied: TTL/h/FOV is less than or equal to 0.045, wherein TTL is the distance between the center of the object side surface of the first lens and the imaging surface of the optical lens on the optical axis; h is the image height corresponding to the maximum field angle of the optical lens; and FOV is the maximum field angle of the optical lens.

In one embodiment, the conditional formula may be satisfied: the BFL/TTL is more than or equal to 0.09, wherein the BFL is the distance from the center of the image side surface of the sixth lens to the imaging surface of the optical lens on the optical axis; and TTL is the distance from the center of the object side surface of the first lens to the imaging surface of the optical lens on the optical axis.

In one embodiment, the conditional formula may be satisfied: D/h/FOV is less than or equal to 0.035, wherein FOV is the maximum field angle of the optical lens; d is the maximum light-passing aperture of the object-side surface of the first lens corresponding to the maximum field angle of the optical lens; and h is the image height corresponding to the maximum field angle of the optical lens.

Another aspect of the present application provides an optical lens that may include, in order from an object side to an image side along an optical axis: the lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. The first lens, the second lens and the fifth lens can all have negative focal power; the third lens, the fourth lens and the sixth lens may each have positive optical power; and the fourth lens, the fifth lens and the sixth lens can be cemented to form a cemented triplet; and can satisfy the conditional expression: TTL/h/FOV is less than or equal to 0.045, wherein TTL is the distance between the center of the object side surface of the first lens and the imaging surface of the optical lens on the optical axis; h is the image height corresponding to the maximum field angle of the optical lens; and FOV is the maximum field angle of the optical lens.

In one embodiment, the object-side surface of the first lens element can be convex and the image-side surface can be concave.

In one embodiment, both the object-side surface and the image-side surface of the second lens can be concave.

In one embodiment, both the object-side surface and the image-side surface of the third lens can be convex.

In one embodiment, both the object-side surface and the image-side surface of the fourth lens can be convex.

In one embodiment, both the object-side surface and the image-side surface of the fifth lens may be concave.

In one embodiment, both the object-side surface and the image-side surface of the sixth lens element can be convex.

In one embodiment, at least three lenses in the optical lens may be aspheric lenses.

In one embodiment, the refractive index of the material of the first lens may be 1.7 or more.

In one embodiment, the conditional formula may be satisfied: the BFL/TTL is more than or equal to 0.09, wherein the BFL is the distance from the center of the image side surface of the sixth lens to the imaging surface of the optical lens on the optical axis; and TTL is the distance from the center of the object side surface of the first lens to the imaging surface of the optical lens on the optical axis.

In one embodiment, the conditional formula may be satisfied: D/h/FOV is less than or equal to 0.035, wherein FOV is the maximum field angle of the optical lens; d is the maximum light-passing aperture of the object-side surface of the first lens corresponding to the maximum field angle of the optical lens; and h is the image height corresponding to the maximum field angle of the optical lens.

The optical lens adopts six lenses, the focal power of each lens is reasonably distributed and the cemented lens is formed by optimally setting the shape of the lens, so that at least one beneficial effect of miniaturization, high pixel, low cost, low sensitivity, convenient assembly and the like of the optical lens is realized.

Drawings

Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments when taken in conjunction with the accompanying drawings. In the drawings:

fig. 1 is a schematic view showing a structure of an optical lens according to embodiment 1 of the present application;

fig. 2 is a schematic structural view showing an optical lens according to embodiment 2 of the present application;

fig. 3 is a schematic structural diagram illustrating an optical lens of a conventional 6-piece architecture;

fig. 4A is an MTF resolution curve at 60 line pairs for an optical lens of a conventional 6-piece architecture;

fig. 4B is a MTF resolution curve showing an optical lens of a conventional 6-piece architecture under the influence of tilt/decentration and the like at 60 line pairs;

FIG. 5A is a graph showing an MTF solution curve at 60 line pairs for an optical lens according to the present application; and

fig. 5B is a graph showing MTF resolution curves at 60 line pairs under the influence of tilt/decentration and the like for an optical lens according to the present application.

Detailed Description

For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of exemplary embodiments of the present application and does not limit the scope of the present application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.

It should be noted that in this specification, the expressions first, second, third, etc. are used only to distinguish one feature from another, and do not represent any limitation on the features. Thus, the first lens discussed below may also be referred to as the second lens or the third lens, and the first cemented lens may also be referred to as the second cemented lens, without departing from the teachings of the present application.

In the drawings, the thickness, size, and shape of the lens have been slightly exaggerated for convenience of explanation. In particular, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings. The figures are purely diagrammatic and not drawn to scale.

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

It will be further understood that the terms "comprises," "comprising," "has," "having," "includes" and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Moreover, when a statement such as "at least one of" appears after a list of listed features, the entirety of the listed features is modified rather than modifying individual elements in the list. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

The features, principles, and other aspects of the present application are described in detail below.

An optical lens according to an exemplary embodiment of the present application includes, for example, six lenses having optical power, i.e., a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. The six lenses are arranged in order from the object side to the image side along the optical axis.

The optical lens according to the exemplary embodiment of the present application may further include a photosensitive element disposed on the image plane. Alternatively, the photosensitive element provided to the imaging surface may be a photosensitive coupling element (CCD) or a complementary metal oxide semiconductor element (CMOS).

The first lens element can have a negative power, and can have a convex object-side surface and a concave image-side surface. The meniscus shape design of the first lens protruding towards the object side can collect large-field light as far as possible, so that the light enters the rear optical system, and the wide-angle function is realized. In practical application, the vehicle-mounted lens is installed outdoors in a use environment, and can be in severe weather such as rain, snow and the like, so that the design of the meniscus shape protruding towards the object space is favorable for the water drop to slide off, and the influence on imaging can be reduced. In addition, the first lens can adopt a high-refractive-index material, for example, the refractive index Nd1 of the material is larger than or equal to 1.7, and the arrangement is favorable for reducing the front end aperture, thereby further improving the imaging quality.

The second lens can have a negative optical power, and both the object-side surface and the image-side surface can be concave. The second lens can disperse light rays, so that the trend of the light rays is in stable transition, and meanwhile, the large-angle light rays enter the rear optical system as far as possible, and the illumination of the system can be improved.

The third lens element can have a positive optical power, and both the object-side surface and the image-side surface can be convex. The third lens can converge light, so that the diffused light can smoothly enter the rear optical system. The focal power of the third lens is positive, which is beneficial to compensating the spherical aberration introduced by the first two groups of lenses.

The fourth lens element can have a positive optical power, and can have a convex object-side surface and a convex image-side surface.

The fifth lens element can have a negative optical power, and can have a concave object-side surface and a concave image-side surface.

The sixth lens element can have a positive optical power, and can have a convex object-side surface and a convex image-side surface.

As known to those skilled in the art, cemented lenses may be used to minimize or eliminate chromatic aberration. The use of the cemented lens in the optical lens can improve the image quality and reduce the reflection loss of light energy, thereby improving the imaging definition of the lens. In addition, the use of the cemented lens can also simplify the assembly process in the lens manufacturing process.

In an exemplary embodiment, the fourth lens, the fifth lens, and the sixth lens may be combined into a triple cemented lens by cementing an image-side surface of the fourth lens with an object-side surface of the fifth lens, and cementing an image-side surface of the fifth lens with an object-side surface of the sixth lens. By introducing the tri-cemented lens, the chromatic aberration influence can be eliminated, the tolerance sensitivity of the system is reduced, and high resolution is realized; meanwhile, the cemented lens may also retain a part of chromatic aberration to balance the entire chromatic aberration of the optical system. The air space between the three lenses can be omitted by gluing the lenses, and the total length of the system is reduced, so that the whole optical system is compact, and the requirement of system miniaturization is met. In addition, the gluing of the lenses can reduce the assembly parts among the three lenses, reduce the assembly process, reduce the cost and reduce the tolerance sensitivity problems of inclination/core deviation and the like of the lens units in the assembly process. Moreover, the gluing of the lenses is beneficial to reducing the light quantity loss caused by reflection between the lenses, and the system illumination can be improved.

In an exemplary embodiment, a diaphragm for limiting the light beam may be disposed between, for example, the third lens and the fourth lens to further improve the imaging quality of the lens. The diaphragm is arranged between the third lens and the tri-cemented lens, and can collect front and rear light rays, shorten the total length of the optical system and reduce the aperture of the front and rear lens groups.

In an exemplary embodiment, TTL/h/FOV ≦ 0.045 may be satisfied between the total optical length TTL of the optical lens, the maximum field angle FOV of the optical lens, and the image height h corresponding to the maximum field angle of the optical lens, and more desirably, TTL, FOV, and h may further satisfy TTL/h/FOV ≦ 0.04. The condition TTL/h/FOV is less than or equal to 0.045, and the miniaturization characteristic of the lens can be realized.

In an exemplary embodiment, the optical back focus BFL of the optical lens and the optical total length TTL of the optical lens may satisfy that BFL/TTL is greater than or equal to 0.09, and further, the BFL and TTL may further satisfy that BFL/TTL is greater than or equal to 0.17. The integral framework of the optical lens is combined, the back focus setting with BFL/TTL more than or equal to 0.09 is met, and the assembly of the optical lens can be facilitated.

In an exemplary embodiment, the maximum field angle FOV of the optical lens, the maximum clear aperture D of the object-side surface of the first lens corresponding to the maximum field angle of the optical lens, and the image height h corresponding to the maximum field angle of the optical lens may satisfy: D/h/FOV ≦ 0.035, and more desirably D, h and FOV may further satisfy D/h/FOV ≦ 0.03. The conditional expression D/h/FOV is less than or equal to 0.035, and the small caliber of the front end of the lens can be ensured.

In an exemplary embodiment, at least three lenses of the optical lens may employ aspheric lenses, for example, the second lens, the fourth lens, the fifth lens and the sixth lens may each employ aspheric lenses. Alternatively, the fourth lens, the fifth lens and the sixth lens are all aspheric lenses. The aspheric lens has the characteristics that: the curvature varies continuously from the center of the lens to the periphery. Unlike a spherical lens having a constant curvature from the center to the periphery of the lens, an aspherical lens has better curvature radius characteristics, and has the advantages of improving distortion aberration and improving astigmatic aberration. After the aspheric lens is adopted, the aberration generated in imaging can be eliminated as much as possible, so that the imaging quality of the lens is improved.

In an exemplary embodiment, the lens used in the optical lens may be a plastic lens, or may be a glass lens. Because the thermal expansion coefficient of the lens made of plastic is large, when the ambient temperature change of the lens is large, the lens made of plastic causes the optical back focus variation of the lens to be large. And the glass lens can reduce the influence of temperature on the optical back focus of the lens. Ideally, the first lens of the optical lens according to the present application may be a glass lens, so as to enhance the performance of the lens under the conditions of high and low temperature, reduce the influence of the environment on the whole system, and improve the overall performance of the optical lens. Furthermore, the first lens can adopt a glass aspheric lens, so that the imaging quality is further improved, and the caliber of the front end is reduced.

According to the optical lens of the embodiment of the application, by reasonably matching the shape and focal power of the lens, the chromatic aberration of the system can be reduced, the TTL is shortened, and the image quality is ensured to be clear while the resolving power is improved; and the application of the aspheric surface can further improve the resolution quality. This optical lens can effectively reduce tolerance sensitivity through using three cemented lens, the equipment of being convenient for optical system overall structure is compact, shortens TTL, reduces the light reflection between lens and lens simultaneously, promotes the illuminance. The optical lens achieves the effect of reducing the cost by saving the fixing pieces among the fourth lens, the fifth lens and the sixth lens, reducing the assembly parts and the assembly processes and reducing the tolerance sensitivity of the sixth lens.

However, it will be appreciated by those skilled in the art that the number of lenses constituting the lens barrel may be varied to achieve the various results and advantages described in the present specification without departing from the claimed subject matter. For example, although six lenses are exemplified in the embodiment, the optical lens is not limited to including six lenses. The optical lens may also include other numbers of lenses, if desired.

Specific examples of an optical lens applicable to the above-described embodiments are further described below with reference to the drawings.

Example 1

An optical lens according to embodiment 1 of the present application is described below with reference to fig. 1. Fig. 1 shows a schematic structural diagram of an optical lens according to embodiment 1 of the present application.

As shown in fig. 1, the optical lens includes, in order from the object side to the image side along the optical axis, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6.

The first lens L1 is a meniscus lens with negative power, with the object side S1 being convex and the image side S2 being concave.

The second lens L2 is a biconcave lens with negative power, and has a concave object-side surface S3 and a concave image-side surface S4. The second lens element L2 is an aspherical lens, and both the object-side surface S3 and the image-side surface S4 are aspherical.

The third lens L3 is a biconvex lens with positive power, and has a convex object-side surface S5 and a convex image-side surface S6.

The fourth lens element L4 is a biconvex lens with positive power, and has a convex object-side surface S8 and a convex image-side surface S9. The fourth lens element L4 is an aspherical lens, and both the object-side surface S8 and the image-side surface S9 are aspherical.

The fifth lens L5 is a biconcave lens with negative power, and has a concave object-side surface S9 and a concave image-side surface S10. The fifth lens element L5 is an aspherical lens, and the image-side surface S10 thereof is aspherical.

The sixth lens element L6 is a biconvex lens with positive refractive power, and has a convex object-side surface S10 and a convex image-side surface S11. The sixth lens element L6 is an aspherical lens, and both the object-side surface S10 and the image-side surface S11 are aspherical.

The fourth lens L4, the fifth lens L5 and the sixth lens L6 are cemented together to form a triple cemented lens.

Optionally, the optical lens may further include a filter L7 and/or a protective lens L7' having an object side S12 and an image side S13. Filter L7 can be used to correct for color deviations. The protective lens L7' may be used to protect the image sensing chip on the imaging plane IMA. Light from the object passes through each of the surfaces S1 to S13 in sequence and is finally imaged on the imaging plane IMA.

In the optical lens of the present embodiment, a stop STO may be provided between the third lens L3 and the fourth lens L4 to improve the imaging quality.

Table 1 shows a radius of curvature R, a thickness T, a refractive index Nd, and an abbe number Vd of each lens of the optical lens of example 1, where the radius of curvature R and the thickness T are both in units of millimeters (mm).

TABLE 1

Flour mark	Radius of curvature R	Thickness T	Refractive index Nd	Abbe number Vd
					1	13.9615	1.1000	1.80	45.3
2	5.0431	2.6492
					3	-43.5200	0.9500	1.50	56.8
4	1.6853	3.7200
					5	7.0000	3.3900	1.52	64.2
6	-7.0000	0.0807
					STO	All-round	0.0268
8	5.3158	2.1201	1.53	56.1
					9	-2.4448	0.7065	1.64	23.5
10	4.4178	1.4200	1.54	56.1
					11	-2.3704	0.1487
12	All-round	0.9500	1.52	64.2
					13	All-round	2.3486
IMA	All-round

The present embodiment adopts six lenses as an example, and by reasonably distributing the focal power and the surface type of each lens, the center thickness of each lens and the air space between each lens, the lens has at least one beneficial effect of miniaturization, aberration balance, low sensitivity, high pixel, low cost and the like. Each aspherical surface type Z is defined by the following formula:

wherein Z is the distance rise from the vertex of the aspheric surface when the aspheric surface is at the position with the height of H along the optical axis direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 1 above); k is the conic coefficient conc; A. b, C, D, E are all high order term coefficients. Table 2 below shows the conic coefficients k and high-order term coefficients A, B, C, D and E of the aspherical lens surfaces S3, S4, S8, S9, S10 and S11 that can be used in example 1.

TABLE 2

Flour mark

K

A

B

C

D

E

3

60.00

3.6174E-04

-6.4552E-05

2.6299E-06

-5.0388E-08

-1.7975E-10

4

-1.21

7.2806E-03

3.5115E-06

3.7080E-05

1.9553E-06

2.0373E-06

8

14.23

-7.6842E-03

1.0249E-03

-6.7822E-03

3.4674E-03

-4.1802E-04

9

0.69

-1.0912E-01

-2.1359E-02

6.7750E-03

-5.0203E-03

5.2049E-04

10

-3.24

-1.1096E-02

-6.2650E-03

-1.7676E-04

5.0974E-04

-7.1381E-05

11

-1.99

-1.2140E-02

1.1511E-03

3.2013E-04

5.8039E-05

-6.5373E-06

Table 3 below gives an optical back focus BFL of the optical lens of embodiment 1 (i.e., an on-axis distance from the center of the image-side surface S11 of the last lens sixth lens L6 to the imaging surface S14), an optical total length TTL of the optical lens (i.e., an on-axis distance from the center of the object-side surface S1 of the first lens L1 to the imaging surface S14), a maximum field angle FOV of the optical lens, a maximum clear aperture D of the object-side surface S1 of the first lens L1 corresponding to the maximum field angle of the optical lens, an image height h corresponding to the maximum field angle of the optical lens, and a refractive index Nd1 of the material of the first lens L1.

TABLE 3

Parameter(s)	BFL(mm)	TTL(mm)	FOV(°)	D(mm)	h(mm)	Nd1
							Numerical value	3.447	19.611	192	13.701	3.958	1.80

In the present embodiment, D/h/FOV is 0.018 between the maximum field angle FOV of the optical lens, the maximum clear aperture D of the object-side surface S1 of the first lens L1 corresponding to the maximum field angle of the optical lens, and the image height h corresponding to the maximum field angle of the optical lens; the BFL/TTL between the optical back focus BFL of the optical lens and the optical total length TTL of the optical lens is 0.176; and the total optical length TTL of the optical lens, the maximum view field angle FOV of the optical lens and the image height h corresponding to the maximum view field angle of the optical lens meet the condition that TTL/h/FOV is 0.026.

Example 2

An optical lens according to embodiment 2 of the present application is described below with reference to fig. 2. In this embodiment and the following embodiments, descriptions of parts similar to those of embodiment 1 will be omitted for the sake of brevity. Fig. 2 shows a schematic structural diagram of an optical lens according to embodiment 2 of the present application.

As shown in fig. 2, the optical lens includes, in order from the object side to the image side along the optical axis, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6.

The first lens L1 is a meniscus lens with negative power, with the object side S1 being convex and the image side S2 being concave.

The second lens L2 is a biconcave lens with negative power, and has a concave object-side surface S3 and a concave image-side surface S4. The second lens element L2 is an aspherical lens, and both the object-side surface S3 and the image-side surface S4 are aspherical.

The third lens L3 is a biconvex lens with positive power, and has a convex object-side surface S5 and a convex image-side surface S6.

The fourth lens element L4 is a biconvex lens with positive power, and has a convex object-side surface S8 and a convex image-side surface S9. The fourth lens element L4 is an aspherical lens, and both the object-side surface S8 and the image-side surface S9 are aspherical.

The fifth lens L5 is a biconcave lens with negative power, and has a concave object-side surface S9 and a concave image-side surface S10. The fifth lens element L5 is an aspherical lens, and the image-side surface S10 thereof is aspherical.

The sixth lens element L6 is a biconvex lens with positive refractive power, and has a convex object-side surface S10 and a convex image-side surface S11. The sixth lens element L6 is an aspherical lens, and both the object-side surface S10 and the image-side surface S11 are aspherical.

The fourth lens L4, the fifth lens L5 and the sixth lens L6 are cemented together to form a triple cemented lens.

Optionally, the optical lens may further include a filter L7 and/or L7' having an object side S12 and an image side S13. Filter L7 can be used to correct for color deviations. The protective lens L7' may be used to protect the image sensing chip on the imaging plane IMA. Light from the object passes through each of the surfaces S1 to S13 in sequence and is finally imaged on the imaging plane IMA.

In the optical lens of the present embodiment, a stop STO may be provided between the third lens L3 and the fourth lens L4 to improve the imaging quality.

Table 4 below shows a radius of curvature R, a thickness T, a refractive index Nd, and an abbe number Vd of each lens of the optical lens of example 2, where the radius of curvature R and the thickness T are both in units of millimeters (mm). Table 5 below shows the conic coefficients k and high-order term coefficients A, B, C, D and E that can be used for the aspherical lens surfaces S3, S4, S8, S9, S10 and S11 in example 2. Table 6 below gives an optical back focus BFL of the optical lens of example 2 (i.e., an on-axis distance from the center of the image-side surface S11 of the last lens sixth lens L6 to the imaging surface S14), an optical total length TTL of the optical lens (i.e., an on-axis distance from the center of the object-side surface S1 of the first lens L1 to the imaging surface S14), a maximum field angle FOV of the optical lens, a maximum clear aperture D of the object-side surface S1 of the first lens L1 corresponding to the maximum field angle of the optical lens, an image height h corresponding to the maximum field angle of the optical lens, and a refractive index Nd1 of the material of the first lens L1.

TABLE 4

Flour mark	Radius of curvature R	Thickness T	Refractive index Nd	Abbe number Vd
					1	13.9303	1.1000	1.78	46.6
2	5.0237	2.6259
					3	-43.9992	0.9500	1.54	56.1
4	1.6846	3.6888
					5	9.8500	3.3816	1.72	23.8
6	-9.8500	0.0795
					STO	All-round	0.0268
8	5.2000	2.1208	1.51	56.8
					9	-2.4463	0.7046	1.64	23.5
10	4.2580	1.4100	1.54	56.1
					11	-2.3686	0.1487
12	All-round	0.9500	1.52	64.2
					13	All-round	3.3256
IMA	All-round

TABLE 5

Flour mark

K

A

B

C

D

E

3

75.00

3.6285E-04

-6.4563E-05

3.6261E-06

-5.0806E-08

-3.1606E-10

4

-0.72

7.2600E-03

-1.4129E-06

3.6207E-05

1.8224E-06

4.0237E-06

8

14.00

-7.6834E-03

1.0265E-03

-6.7760E-03

3.4752E-03

-2.4124E-03

9

0.75

-1.0926E-01

-2.1347E-02

6.7992E-03

-5.0151E-03

3.5173E-03

10

-3.20

-1.1044E-02

-6.2696E-03

-1.7901E-04

5.1027E-04

-7.0496E-05

11

-1.99

-1.2140E-02

1.1520E-03

3.2034E-04

5.8092E-05

-8.5180E-06

TABLE 6

Parameter(s)	BFL(mm)	TTL(mm)	FOV(°)	D(mm)	h(mm)	Nd1
							Numerical value	4.424	20.512	192	13.747	4.094	1.78

In the present embodiment, D/h/FOV is 0.017 when D/h/FOV is satisfied between the maximum field angle FOV of the optical lens, the maximum light-transmitting aperture D of the object-side surface S1 of the first lens L1 corresponding to the maximum field angle of the optical lens, and the image height h corresponding to the maximum field angle of the optical lens; the BFL/TTL between the optical back focus BFL of the optical lens and the optical total length TTL of the optical lens is 0.216; and the total optical length TTL of the optical lens, the maximum view field angle FOV of the optical lens and the image height h corresponding to the maximum view field angle of the optical lens meet the condition that TTL/h/FOV is 0.026.

In summary, examples 1 to 2 each satisfy the relationship shown in table 7 below.

TABLE 7

Conditions/examples	1	2
			D/h/FOV	0.018	0.017
BFL/TTL	0.176	0.216
			TTL/h/FOV	0.026	0.026

The optical lens according to the above-described embodiment of the present application is different in architecture from a conventional six-piece lens. According to the overall structure of the present application, tolerance sensitivity of the sixth lens is high, such as tilt/decentration, and once problems such as tilt/decentration occur, the influence on the imaging quality of the system is large. As shown in fig. 3, the gluing member of the conventional six-piece structure is separated from the sixth lens, and the deviation of the sixth lens caused by assembly during assembly is very likely to affect the imaging quality of the system. However, according to the optical lens of the present application, since the fourth lens, the fifth lens and the sixth lens are formed as an assembly, the sixth lens is not easily deviated due to assembly, and thus the imaging quality of the system is not affected.

Fig. 4A to 5B show MTF resolution curves of an optical lens of a conventional 6-piece architecture and an optical lens according to the present application at the same line pair. Referring to fig. 4A and 4B, in the optical lens of the conventional 6-piece structure, the imaging effect of the lens is greatly reduced due to the tilt/decentration of the sixth lens element in the assembling process, and under the spatial frequency of 60lp/mm resolution, the central MTF (modulation Transfer function) is kept at about 0.9 and slightly reduced, while the edge MTF is reduced from about 0.75 to about 0.55, which shows that the imaging effect of the system is greatly influenced. Referring to fig. 5A and 5B, it can be seen that the tilt/decentration of the sixth lens has little influence on the imaging effect of the optical lens according to the present application, and at a spatial frequency of a solution of 60lp/mm, the central MTF is still maintained at 0.9, while the edge MTF is also maintained at about 0.75, which is slightly decreased, and the curve is more concentrated and the solution is higher. As can be known by referring to the drawings for comparison, the optical lens can effectively reduce the influence of the problems of inclination/core deviation and the like on the imaging effect, is convenient to assemble, and has a compact integral structure and higher resolving power.

The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention as referred to in the present application is not limited to the embodiments with a specific combination of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims (18)

1. The optical lens sequentially comprises from an object side to an image side along an optical axis: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens,

it is characterized in that the preparation method is characterized in that,

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, and both the object side surface and the image side surface of the second lens are concave;

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, the fifth lens and the sixth lens are cemented to form a triple cemented lens;

the fourth lens has a positive optical power, the fifth lens has a negative optical power, and the sixth lens has a positive optical power;

the number of lenses with focal power in the optical lens is six; and

the conditional expression is satisfied: D/h/FOV multiplied by 180 degrees is less than or equal to 6.3,

wherein the FOV is the maximum field angle of the optical lens;

d is the maximum light-passing aperture of the object-side surface of the first lens corresponding to the maximum field angle of the optical lens; and

h is the image height corresponding to the maximum field angle of the optical lens.

2. An optical lens as recited in claim 1, wherein the fourth lens element has a positive optical power, and wherein both the object-side surface and the image-side surface are convex.

3. An optical lens barrel according to claim 1, wherein the fifth lens element has a negative power and both the object-side surface and the image-side surface are concave.

4. An optical lens barrel according to claim 1, wherein the sixth lens element has a positive optical power, and both the object-side surface and the image-side surface thereof are convex.

5. An optical lens according to claim 1, characterized in that at least three lenses in the optical lens are aspherical lenses.

6. An optical lens according to claim 1, characterized in that the refractive index of the material of the first lens is 1.7 or more.

7. An optical lens according to any one of claims 1 to 6, characterized in that the conditional expression is satisfied: TTL/h/FOV multiplied by 180 degrees is less than or equal to 8.1,

wherein, TTL is a distance on the optical axis from a center of an object-side surface of the first lens element to an imaging surface of the optical lens;

h is the image height corresponding to the maximum field angle of the optical lens; and

the FOV is the maximum field angle of the optical lens.

8. An optical lens according to any one of claims 1 to 6, characterized in that the conditional expression is satisfied: the BFL/TTL is more than or equal to 0.09,

the BFL is the distance from the center of the image side surface of the sixth lens to the imaging surface of the optical lens on the optical axis; and

TTL is a distance on the optical axis from the center of the object-side surface of the first lens element to the imaging surface of the optical lens.

9. The optical lens sequentially comprises from an object side to an image side along an optical axis: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens,

it is characterized in that the preparation method is characterized in that,

the first lens, the second lens and the fifth lens each have a negative optical power;

the third lens, the fourth lens and the sixth lens each have positive optical power;

the object side surface of the second lens is a concave surface;

the number of lenses with focal power in the optical lens is six;

the fourth lens, the fifth lens and the sixth lens are cemented to form a triple cemented lens; and

the conditional expression is satisfied: TTL/h/FOV multiplied by 180 degrees is less than or equal to 8.1, D/h/FOV multiplied by 180 degrees is less than or equal to 6.3,

wherein, TTL is a distance on the optical axis from a center of an object-side surface of the first lens element to an imaging surface of the optical lens;

h is the image height corresponding to the maximum field angle of the optical lens;

the FOV is the maximum field angle of the optical lens; and

and D is the maximum light-passing aperture of the object-side surface of the first lens corresponding to the maximum field angle of the optical lens.

10. An optical lens barrel according to claim 9, wherein the object side surface of the first lens element is convex and the image side surface of the first lens element is concave.

11. An optical lens barrel according to claim 9, wherein the image side surface of the second lens is concave.

12. An optical lens barrel according to claim 9, wherein the object-side surface and the image-side surface of the third lens are convex.

13. An optical lens barrel according to claim 9, wherein the object-side surface and the image-side surface of the fourth lens are convex.

14. An optical lens barrel according to claim 9, wherein the fifth lens element has both object and image side surfaces that are concave.

15. An optical lens barrel according to claim 9, wherein the object-side surface and the image-side surface of the sixth lens element are convex.

16. An optical lens according to claim 9, characterized in that the refractive index of the material of the first lens is 1.7 or more.

17. An optical lens according to any one of claims 9-16, characterized in that at least three lenses in the optical lens are aspherical lenses.

18. An optical lens according to any one of claims 9 to 16, characterized in that: the BFL/TTL is more than or equal to 0.09,

the BFL is the distance from the center of the image side surface of the sixth lens to the imaging surface of the optical lens on the optical axis; and

TTL is a distance on the optical axis from the center of the object-side surface of the first lens element to the imaging surface of the optical lens.

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