CN111221099A

CN111221099A - Optical lens and imaging apparatus

Info

Publication number: CN111221099A
Application number: CN201811414685.9A
Authority: CN
Inventors: 王东方; 赵哲; 周宝
Original assignee: Ningbo Sunny Automotive Optech Co Ltd
Current assignee: Ningbo Sunny Automotive Optech Co Ltd
Priority date: 2018-11-26
Filing date: 2018-11-26
Publication date: 2020-06-02
Anticipated expiration: 2038-11-26
Also published as: CN111221099B

Abstract

An optical lens and an imaging apparatus including the same are disclosed. The optical lens 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, the object side surface of the first lens is a concave surface, and the image side surface of the first lens is a convex surface; the second lens can have positive focal power, and 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 can have positive focal power, and both the object side surface and the image side surface of the third lens are convex surfaces; the fourth lens can have positive focal power, and both the object side surface and the image side surface of the fourth lens are convex surfaces; the fifth lens element may have a negative focal power, and both the object-side surface and the image-side surface thereof may be concave; and the sixth lens element can have a positive power, and has a convex object-side surface and a concave image-side surface. According to the optical lens, at least one of the advantages of high resolution, miniaturization, small front end aperture, large aperture, low cost and the like can be achieved.

Description

Optical lens and imaging apparatus

Technical Field

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

Background

The automatic driving and intelligent transportation is a hot topic and a key research direction in the current automobile industry, and an optical lens is an indispensable component in an automatic driving system as the eyes of an automobile and plays an important role in target recognition and data acquisition.

The performance requirements of the optical lens for general vehicle-mounted application are very high, and the requirements of the optical lens for automatic driving are more strict; the automobile driving system is small and attractive, has extremely high resolving power and can meet the application requirement of automatic driving. Generally, on the basis of the original optical lens for vehicle-mounted applications, the optical lens for automatic driving has 6, 7 or more lens structures to improve the resolution, but this seriously affects the miniaturization of the lens and increases the cost. Meanwhile, in order to better realize clear recognition of low-light environments, such optical lenses usually need a large aperture.

Therefore, there is an urgent need in the market for an optical lens with high resolution, small size, low cost, and suitability for low-light 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, the object side surface of the first lens is a concave surface, and the image side surface of the first lens is a convex surface; the second lens can have positive focal power, and 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 can have positive focal power, and both the object side surface and the image side surface of the third lens are convex surfaces; the fourth lens can have positive focal power, and both the object side surface and the image side surface of the fourth lens are convex surfaces; the fifth lens element may have a negative focal power, and both the object-side surface and the image-side surface thereof may be concave; and the sixth lens element can have a positive power, and has a convex object-side surface and a concave image-side surface.

In one embodiment, the fourth lens and the fifth lens may be cemented with each other to form a cemented lens.

In one embodiment, the first lens and the sixth lens may each be an aspheric lens.

In one embodiment, the total optical length TTL of the optical lens and the entire focal length F of the optical lens may satisfy: TTL/F is less than or equal to 3.5.

In one 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 is less than or equal to 0.065.

In one embodiment, the optical back focus BFL of the optical lens and the lens group length TL of the optical lens may satisfy: BFL/TL is more than or equal to 0.1.

In one embodiment, the focal length value F4 of the fourth lens and the focal length value F of the whole group of the optical lens satisfy: F4/F is more than or equal to 0.5 and less than or equal to 1.5.

In one embodiment, the focal length value F4 of the fourth lens and the focal length value F3 of the third lens satisfy: F4/F3 is less than or equal to 1.5.

In one embodiment, the combined focal length value F45 of the fourth lens and the fifth lens and the entire set of focal length values F of the optical lens may satisfy: F45/F is more than or equal to 0.5 and less than or equal to 2.5.

In one embodiment, a radius of curvature R7 of the image-side surface of the third lens and a radius of curvature R8 of the object-side surface of the fourth lens may satisfy: the ratio of (R7+ R8)/(R7-R8) is more than or equal to-1 and less than or equal to 1.

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. Wherein the first lens and the fifth lens can both have negative focal power; the second lens, the third lens, the fourth lens and the sixth lens can all have positive focal power; the fourth lens and the fifth lens can be mutually glued to form a cemented lens; and the total optical length TTL of the optical lens and the whole group of focal length values F of the optical lens can meet the following requirements: TTL/F is less than or equal to 3.5.

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

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

Still another aspect of the present application provides an imaging apparatus that may include the optical lens according to the above-described embodiment and an imaging element for converting an optical image formed by the optical lens into an electrical signal.

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 of the beneficial effects of high resolution, miniaturization, small front end caliber, large aperture, low cost 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; and

fig. 2 is a schematic view showing a structure of an optical lens according to embodiment 2 of 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 concave object-side surface and a convex image-side surface. The first lens is arranged in a meniscus shape with the convex surface facing the image side, so that the focal power of the optical system can be balanced, and the field curvature of the image surface can be effectively corrected.

The second lens element can have a positive power, and can have a convex object-side surface and a concave image-side surface. The second lens is designed into a meniscus shape with the convex surface facing the object side, so that light rays with a large field of view can be collected as far as possible, the light rays enter a rear optical system, and the light flux is increased.

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 is set to have positive focal power, and a third lens with positive focal power is used after the aperture stop is set, so that aberration generated by the front lens group can be further corrected, and meanwhile, light beams are converged again, so that the aperture of the lens can be enlarged, the total length of the lens can be shortened, the optical system is more compact, and the optical system has relatively shorter total length of the lens.

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 concave image-side surface. The shape design of the convex object side surface of the sixth lens can focus more light rays to enter the image surface, so that strong image surface illumination is obtained, and the total length can be reduced due to the large curvature of the object side surface of the lens.

In an exemplary embodiment, a diaphragm for limiting the light beam may be disposed between, for example, the first lens and the second lens to further improve the imaging quality of the lens. The diaphragm can effectively collect light rays entering the optical system, the aperture of the lens of the optical system is reduced, and the large aperture is realized. It should be noted, however, that the positions of the diaphragms disclosed herein are merely examples and not limitations; in alternative embodiments, the diaphragm may be disposed at other positions according to actual needs, for example, the diaphragm may also be disposed between the second lens and the third lens.

In an exemplary embodiment, the optical lens according to the present application may further include a filter disposed between the sixth lens and the imaging surface to filter light rays having different wavelengths, as necessary; and may further include a protective glass disposed between the optical filter and the imaging surface to prevent internal elements (e.g., chips) of the optical lens from being damaged.

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 and the fifth lens may be combined into a cemented lens by cementing the image-side surface of the fourth lens with the object-side surface of the fifth lens. The cemented lens consists of a positive lens (namely, a fourth lens) and a negative lens (namely, a fifth lens), so that the air interval can be effectively reduced, and the total length of the system is reduced; the assembly process can be reduced, and the cost is reduced; the tolerance sensitivity problems of inclination/core deviation and the like generated in the assembling process of the lens unit can be reduced; the light quantity loss caused by reflection between the lenses can be reduced, and the illumination intensity is improved; in addition, the cemented lens itself can be achromatic, which can further reduce curvature of field and correct the off-axis point aberration of the system. The use of the cemented lens shares the whole chromatic aberration correction of the system, can effectively correct the aberration so as to improve the resolution, and ensures that the optical system is integrally compact and meets the miniaturization requirement.

In an exemplary embodiment, an optical total length TTL of the optical lens and a whole set of focal length values F of the optical lens may satisfy: TTL/F is less than or equal to 3.5, and more ideally, TTL/F is less than or equal to 3. The condition TTL/F is less than or equal to 3.5, and the miniaturization characteristic of the system can be ensured.

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 is less than or equal to 0.065, and more preferably, D/H/FOV is less than or equal to 0.06. The requirement of the conditional expression D/H/FOV is less than or equal to 0.065, the small caliber at the front end can be ensured, and the miniaturization characteristic is realized.

In an exemplary embodiment, the optical back focus BFL of the optical lens and the lens group length TL of the optical lens may satisfy: the BFL/TL ratio is more than or equal to 0.1, and more ideally, the BFL/TL ratio is more than or equal to 0.15. By satisfying the conditional expression BFL/TL is more than or equal to 0.1, the characteristic of the back focal length can be satisfied on the basis of realizing miniaturization, and the assembly of the optical lens is facilitated. In addition, the lens group length TL is shorter, so that the system structure is compact, the sensitivity of the lens to the modulation transfer function MTF is reduced, the production yield is improved, and the production cost is reduced.

In an exemplary embodiment, a focal length value F4 of the fourth lens and a focal length value F of the entire group of the optical lens may satisfy: F4/F is 0.5. ltoreq. F4/F is 1.5, and more preferably, it further satisfies 0.8. ltoreq. F4/F. ltoreq.1.2. By reasonably distributing the focal power of the lens, the resolution quality can be improved.

In an exemplary embodiment, a focal length value F4 of the fourth lens and a focal length value F3 of the third lens may satisfy: F4/F3 is not more than 1.5, and more preferably, F4/F3 is not more than 1. The smooth transition of light can be facilitated by reasonably setting the focal lengths of the two adjacent lenses.

In an exemplary embodiment, a combined focal length value F45 of the fourth lens and the fifth lens and a full set focal length value F of the optical lens may satisfy: F45/F is 0.5. ltoreq. F45/F is 2.5, and more preferably 1. ltoreq. F45/F. ltoreq.2. By satisfying the conditional expression that F45/F is more than or equal to 0.5 and less than or equal to 2.5, the light trend can be favorably controlled, the aberration caused by the entering large-angle light can be reduced, and meanwhile, the structure of the lens is compact, and the miniaturization is favorably realized.

In an exemplary embodiment, a radius of curvature R7 of the image-side surface of the third lens and a radius of curvature R8 of the object-side surface of the fourth lens may satisfy: (R7+ R8)/(R7-R8) is not more than 1, more preferably not more than-0.5 (R7+ R8)/(R7-R8) is not more than 0.5. Satisfying the conditional expression-1 ≦ (R7+ R8)/(R7-R8) ≦ 1, correcting aberrations of the optical system, and ensuring that an incident angle is not too large when the light exiting from the third lens is incident on the first surface of the fourth lens, thereby reducing tolerance sensitivity of the optical system; if the aberration exceeds the upper limit value, the aberration of the optical system cannot be sufficiently corrected; if the light intensity is lower than the lower limit value, the incident angle of the light emitted from the third lens when entering the first surface of the fourth lens is too large, which increases the sensitivity of the optical system.

In an exemplary embodiment, the first lens and the sixth lens in the optical lens according to the present application may employ aspherical 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. For example, the first lens element may be an aspheric lens element to correct aberrations of the optical system, thereby improving the resolution of the optical system and making the overall structure relatively simple. The sixth lens can be an aspheric lens, so that various aberrations of the optical system can be fully corrected, and the resolution can be improved on the premise of compact structure. It is to be understood that the optical lens according to the present application may also increase the number of aspherical lenses in order to improve the imaging quality.

In an exemplary embodiment, the lens used in the optical lens may be a plastic lens, or may be a glass lens. The lens made of plastic has a large thermal expansion coefficient, and when the ambient temperature change of the lens is large, the lens made of plastic causes a large amount of change of the optical back focus of the lens. The glass lens can reduce the influence of temperature on the optical back focus of the lens, but has higher cost.

According to the optical lens of the above embodiment of the present application, through reasonable lens shape setting and optical power setting, high resolution can be achieved only by using 6-piece structure, and meanwhile, the low cost requirements of small lens volume, low sensitivity and high production yield can be met. The optical lens has a large aperture, is good in imaging effect, can achieve high-definition level of image quality, and can ensure the definition of images even in a low-light environment or at night. Therefore, the optical lens according to the above-described embodiment of the present application can have at least one of the advantages of high resolution, miniaturization, small aperture at the front end, large aperture, low cost, and the like, and can better meet the application requirements of, for example, an in-vehicle lens.

It will be understood by those skilled in the art that the total optical length TTL of the optical lens used above refers to the on-axis distance from the center of the object-side surface of the first lens to the center of the imaging surface; the optical back focus BFL of the optical lens refers to the axial distance from the center of the image side surface of the sixth lens of the last lens to the center of the imaging surface; and the lens group length TL of the optical lens means an on-axis distance from the center of the object side surface of the first lens to the center of the image side surface of the sixth lens of the last lens.

It will be understood by those skilled in the art that the number of lenses making up the lens barrel may be varied to achieve the various results and advantages described in this 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 concave and the image side S2 being convex.

The second lens L2 is a meniscus lens with positive power, with the object side S4 being convex and the image side S5 being concave.

The third lens L3 is a biconvex lens with positive optical power, and has both the object-side surface S6 and the image-side surface S7 being convex.

The fourth lens L4 is a biconvex lens with positive optical power, and has both the object-side surface S8 and the image-side surface S9 convex. The fifth lens L5 is a biconcave lens with negative optical power, and both the object-side surface S9 and the image-side surface S10 are concave. Wherein the fourth lens L4 and the fifth lens L5 are cemented with each other to form a cemented lens.

The sixth lens L6 is a meniscus lens with positive power, with the object side S11 being convex and the image side S12 being concave.

The first lens element L1 and the sixth lens element L6 are both aspheric lenses, and both the object-side surface and the image-side surface thereof are aspheric.

Optionally, the optical lens may further include a filter L7 and/or a protective lens L7' having an object side S13 and an image side S14. 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 S14 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 first lens L1 and the second lens L2 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	-16.4144	3.5000	1.59	61.16
2	-101.8048	0.1000
					STO	All-round	-1.3650
4	26.9824	6.0000	1.62	56.73
					5	75.3111	1.1368
6	56.8330	6.1081	1.62	63.42
					7	-25.6506	0.1000
8	13.8218	5.5000	1.62	63.42
					9	-48.6215	1.0000	1.76	27.55
10	14.6334	3.0515
					11	8.9979	7.7161	1.70	55.53
12	9.0169	1.7000
					13	All-round	0.9500	1.52	64.20
14	All-round	3.1157
					15	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 can have at least one of the advantages of high resolution, miniaturization, small front end aperture, large aperture, 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 cone coefficients k and high-order term coefficients A, B, C, D and E of aspherical lens surfaces S1 to S2 and S11 to S12 that can be used in example 1.

TABLE 2

Flour mark

K

A

B

C

D

E

1

0.0000

-1.0674E-04

9.0000E-07

-8.0000E-09

1.4331E-10

-6.8727E-13

2

0.0000

-6.8967E-05

1.0000E-06

-6.0000E-09

4.3741E-11

-1.4181E-13

11

-1.0029

-1.1250E-04

5.9499E-07

-8.7766E-09

2.2333E-10

-2.5265E-12

12

-3.0853

9.4842E-04

-2.3058E-06

3.5857E-07

-3.0521E-09

-2.1627E-12

Table 3 below gives the radius of curvature R7 of the image-side surface S7 of the third lens L3, the radius of curvature R8 of the object-side surface S8 of the fourth lens L4, the total optical length TTL of the optical lens (i.e., the on-axis distance from the center of the object-side surface S1 of the first lens L1 to the imaging surface IMA), the entire group focal length value F of the optical lens, the focal length value F45 of the cemented lens composed of the fourth lens L4 and the fifth lens L5, the focal length values F3-F4 of the third lens L3 to the fourth lens L4, 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, the image height H corresponding to the maximum field angle of the optical lens, the maximum field angle FOV of the optical lens, the optical back focus BFL of the optical lens (i.e., the on-axis distance from the imaging surface S12 of the sixth lens L6 of the last lens), and the lens group length (i.e., the on-axis distance from the center of the object-side surface S1 of the first lens L1 to the center of the image-side surface S12 of the last lens sixth lens L6).

TABLE 3

R7(mm)	-25.6506	D(mm)	15.9531
				R8(mm)	13.8218	H(mm)	9.4740
TTL(mm)	39.9781	FOV(°)	31.2000
				F(mm)	16.3227	BFL(mm)	5.7657
F45(mm)	23.5816	TL(mm)	34.2124
				F3(mm)	29.3339
F4(mm)	17.9619

In the present embodiment, TTL/F is 2.4492 between the total optical length TTL of the optical lens and the whole focal length F of the optical lens; 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 satisfy a D/H/FOV of 0.0540; the distance between the optical back focus BFL of the optical lens and the lens group length TL of the optical lens is 0.1685; F4/F1.1004 is satisfied between the focal length value F4 of the fourth lens L4 and the focal length value F of the entire group of optical lenses; F4/F3 is 0.6123 between the focal length value F4 of the fourth lens L4 and the focal length value F3 of the third lens L3; F45/F1.4447 is satisfied between the focal length value F45 of the cemented lens composed of the fourth lens L4 and the fifth lens L5 and the focal length value F of the entire group of the optical lens; a radius of curvature R7 of the image-side surface S7 of the third lens L3 and a radius of curvature R8 of the object-side surface S8 of the fourth lens L4 satisfy (R7+ R8)/(R7-R8) ═ 0.2997.

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 second lens L2 is a meniscus lens with positive power, with the object side S3 being convex and the image side S4 being concave.

The first lens element L1 and the sixth lens element L6 are both aspheric lenses, and the object-side surface and/or the image-side surface of each of the lenses are aspheric.

In the optical lens of the present embodiment, a stop STO may be provided between the second lens L2 and the third lens L3 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). The following table 5 shows the conic coefficients k and the high-order term coefficients A, B, C, D and E that can be used for the aspherical lens surfaces S1-S2 and S12 in example 2. Table 6 below gives a curvature radius R7 of the image-side surface S7 of the third lens L3, a curvature radius R8 of the object-side surface S8 of the fourth lens L4, an optical total length TTL of the optical lens, a focal length value F of the entire group of the optical lens, a focal length value F45 of a cemented lens composed of the fourth lens L4 and the fifth lens L5, focal length values F3-F4 of the third lens L3 to the fourth lens L4, a maximum clear aperture D of the object-side surface S1 of the first lens L1 corresponding to the maximum angle of view of the optical lens, an image height H corresponding to the maximum angle of view of the optical lens, a maximum angle of view FOV of the optical lens, an optical back focus BFL of the optical lens, and a lens group length TL of the optical lens in example 2.

TABLE 4

TABLE 5

Flour mark

K

A

B

C

D

E

1

0.0000

2.5418E-04

-2.4686E-06

4.6361E-08

-4.0723E-10

2.0503E-12

2

0.0000

1.9157E-04

-2.4416E-06

3.4798E-08

-2.8227E-10

1.0197E-12

12

-3.0853

9.6785E-04

-1.4621E-06

4.5314E-07

-8.8957E-09

1.9799E-10

TABLE 6

R7(mm)	-30.7679	D(mm)	16.7396
				R8(mm)	14.5613	H(mm)	9.6820
TTL(mm)	41.7186	FOV(°)	31.2000
				F(mm)	16.3564	BFL(mm)	6.4686
F45(mm)	25.4746	TL(mm)	35.2500
				F3(mm)	28.6652
F4(mm)	17.4711

In the present embodiment, TTL/F is 2.5506 between the total optical length TTL of the optical lens and the whole focal length F of the optical lens; 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 satisfy D/H/FOV of 0.0554; the distance between the optical back focus BFL of the optical lens and the lens group length TL of the optical lens is 0.1835; F4/F1.0681 is satisfied between the focal length value F4 of the fourth lens L4 and the focal length value F of the entire group of optical lenses; F4/F3 is 0.6095 between the focal length value F4 of the fourth lens L4 and the focal length value F3 of the third lens L3; F45/F1.5575 is satisfied between the focal length value F45 of the cemented lens composed of the fourth lens L4 and the fifth lens L5 and the focal length value F of the entire group of the optical lens; a radius of curvature R7 of the image-side surface S7 of the third lens L3 and a radius of curvature R8 of the object-side surface S8 of the fourth lens L4 satisfy (R7+ R8)/(R7-R8) ═ 0.3575.

In summary, example 1 and example 2 each satisfy the relationship shown in table 7 below.

TABLE 7

Conditions/examples	1	2
			TTL/F	2.4492	2.5506
D/H/FOV	0.0540	0.0554
			BFL/TL	0.1685	0.1835
F4/F	1.1004	1.0681
			F4/F3	0.6123	0.6095
F45/F	1.4447	1.5575
			(R7+R8)/(R7-R8)	0.2997	0.3575

The present application also provides an imaging apparatus that may include the optical lens according to the above-described embodiment of the present application and an imaging element for converting an optical image formed by the optical lens into an electrical signal. The imaging element may be a photo-coupled device (CCD) or a complementary metal oxide semiconductor device (CMOS). The imaging device may be a stand-alone imaging device such as a range finding camera or may be an imaging module integrated on a device such as a range finding device.

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

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 concave surface, and the image side surface of the first lens is a convex surface;

the second lens has positive 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, and both the object side surface and the image side surface of the fourth lens are convex surfaces;

the fifth lens has negative focal power, and both the object side surface and the image side surface of the fifth lens are concave; and

the sixth lens has positive focal power, and the object side surface of the sixth lens is a convex surface while the image side surface of the sixth lens is a concave surface.

2. An optical lens according to claim 1, wherein the fourth lens and the fifth lens are cemented to each other to form a cemented lens.

3. An optical lens according to claim 1, characterized in that the first lens and the sixth lens are both aspherical lenses.

4. An optical lens according to any one of claims 1 to 3, wherein an overall optical length TTL of the optical lens and a total group focal length value F of the optical lens satisfy: TTL/F is less than or equal to 3.5.

5. An optical lens according to any one of claims 1 to 3, wherein 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 satisfy: D/H/FOV is less than or equal to 0.065.

6. An optical lens according to any of claims 1-3, characterized in that between an optical back focus BFL of the optical lens and a lens group length TL of the optical lens satisfies: BFL/TL is more than or equal to 0.1.

7. An optical lens according to any one of claims 1 to 3, characterized in that the focal length value F4 of the fourth lens and the entire group of focal length values F of the optical lens satisfy: F4/F is more than or equal to 0.5 and less than or equal to 1.5.

8. An optical lens according to any one of claims 1 to 3, characterized in that a focal length value F4 of the fourth lens and a focal length value F3 of the third lens satisfy: F4/F3 is less than or equal to 1.5.

9. An optical lens according to any one of claims 1 to 3, characterized in that a combined focal length value F45 of the fourth lens and the fifth lens and a full set of focal length values F of the optical lens satisfy: F45/F is more than or equal to 0.5 and less than or equal to 2.5.

10. An optical lens barrel according to any one of claims 1 to 3, wherein a radius of curvature R7 of an image side surface of the third lens and a radius of curvature R8 of an object side surface of the fourth lens satisfy: the ratio of (R7+ R8)/(R7-R8) is more than or equal to-1 and less than or equal to 1.

11. 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 and the fifth lens each have a negative optical power;

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

the fourth lens and the fifth lens are mutually glued to form a cemented lens; and

the total optical length TTL of the optical lens and the whole group of focal length values F of the optical lens meet the following conditions: TTL/F is less than or equal to 3.5.

12. An imaging apparatus comprising the optical lens of claim 1 or 11 and an imaging element for converting an optical image formed by the optical lens into an electric signal.