CN115166950A

CN115166950A - Optical lens

Info

Publication number: CN115166950A
Application number: CN202211087463.7A
Authority: CN
Inventors: 章彬炜; 胡芬; 曾昊杰
Original assignee: Jiangxi Lianyi Optics Co Ltd
Current assignee: Jiangxi Lianyi Optics Co Ltd
Priority date: 2022-09-07
Filing date: 2022-09-07
Publication date: 2022-10-11
Anticipated expiration: 2042-09-07
Also published as: CN115166950B

Abstract

The invention discloses an optical lens, which comprises the following components in sequence from an object side to an imaging surface along an optical axis: a first lens element having a negative optical power, an object-side surface of the first lens element being concave at a paraxial region thereof and an image-side surface of the first lens element being concave; a diaphragm; a second lens having a positive refractive power, both the object-side surface and the image-side surface of the second lens being convex; a third lens element having a negative optical power, wherein the object-side surface is convex at a paraxial region and the image-side surface is concave; a fourth lens having a positive refractive power, both the object-side surface and the image-side surface of the fourth lens being convex; a fifth lens element having a negative optical power, an object-side surface being convex at a paraxial region and an image-side surface being concave at the paraxial region; a sixth lens having positive optical power, an object-side surface of which is convex at a paraxial region; the optical lens comprises at least one aspheric lens. The optical lens has the advantages of high pixel, ultra-wide angle and small volume.

Description

Optical lens

Technical Field

The invention relates to the technical field of optical lenses, in particular to an optical lens.

Background

In recent years, with the rapid development of science and technology, the demand of various industries for optical lenses is increasing, and particularly, with the rapid development of emerging optical industries such as the VR/AR industry, users have made higher requirements for imaging devices in the VR/AR field, and the requirements for the imaging quality of lenses matched with the imaging devices are also increasing.

Since VR/AR imaging devices are more frequently used in head-mounted products and portable electronic products, the lens is required to have a smaller volume and a larger field angle to capture a large range of information, and the lens is required to have less distortion in order to restore the information more accurately by the VR/AR imaging device. However, the optical lens used in the prior art generally has the defects of small field angle, low pixel, large volume and the like, and cannot simultaneously meet the requirements of large wide angle, high pixel, miniaturization and the like.

Disclosure of Invention

Therefore, an object of the present invention is to provide an optical lens having advantages of high pixel, ultra-wide angle, and small volume.

The invention provides an optical lens, which sequentially comprises the following components from an object side to an imaging surface along an optical axis: a first lens having a negative optical power, an object-side surface of the first lens being concave at a paraxial region and an image-side surface of the first lens being concave; a diaphragm; the second lens is provided with positive focal power, and the object side surface and the image side surface of the second lens are convex surfaces; a third lens having a negative optical power, an object-side surface of the third lens being convex at a paraxial region, an image-side surface of the third lens being concave; a fourth lens having positive optical power, the fourth lens having both an object-side surface and an image-side surface that are convex; a fifth lens having a negative optical power, an object-side surface of the fifth lens being convex at a paraxial region and an image-side surface of the fifth lens being concave at a paraxial region; a sixth lens having positive optical power, an object-side surface of the sixth lens being convex at a paraxial region; the optical lens comprises at least one aspheric lens.

Compared with the prior art, the optical lens provided by the invention adopts six lenses with specific focal power, and adopts specific surface shape collocation and reasonable focal power distribution, so that the lens has smaller head size and smaller volume, and meanwhile, a wider shooting range is realized; meanwhile, due to the adoption of the reasonable collocation of the aspheric lenses, the off-axis aberration can be reasonably corrected, so that the lens has good resolution.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic structural diagram of an optical lens according to a first embodiment of the present invention;

FIG. 2 is a field curvature graph of an optical lens according to a first embodiment of the present invention;

FIG. 3 is a vertical axis chromatic aberration diagram of an optical lens according to a first embodiment of the present invention;

FIG. 4 is a schematic structural diagram of an optical lens system according to a second embodiment of the present invention;

FIG. 5 is a field curvature graph of an optical lens according to a second embodiment of the present invention;

FIG. 6 is a vertical axis chromatic aberration diagram of an optical lens according to a second embodiment of the present invention;

FIG. 7 is a schematic structural diagram of an optical lens system according to a third embodiment of the present invention;

FIG. 8 is a field curvature graph of an optical lens according to a third embodiment of the present invention;

fig. 9 is a vertical axis chromatic aberration diagram of an optical lens according to a third embodiment of the invention.

Detailed Description

In order to make the objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. Several embodiments of the invention are presented in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Like reference numerals refer to like elements throughout the specification.

The invention provides an optical lens, which sequentially comprises the following components from an object side to an imaging surface along an optical axis: the lens comprises a first lens, a diaphragm, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and an optical filter.

The first lens has negative focal power, the object side surface of the first lens is a concave surface at a paraxial region, and the image side surface of the first lens is a concave surface;

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

the third lens has negative focal power, the object-side surface of the third lens is convex at a paraxial region, and the image-side surface of the third lens is concave;

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

the sixth lens has a positive optical power, and an object-side surface of the sixth lens is convex at a paraxial region;

the optical lens comprises at least one aspheric lens.

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

0<f/f6<0.2；（1）

wherein f6 denotes a focal length of the sixth lens, and f denotes an effective focal length of the optical lens. The condition formula (1) is satisfied, the focal length ratio of the sixth lens can be reasonably controlled and the sixth lens has proper positive focal power, so that the aberration of the optical lens can be corrected, the total length of the lens can be shortened, and the miniaturization of the lens can be realized.

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

-2<f1/f<-1；（2）

-15<R11/R12<-1；（3）

where f1 denotes a focal length of the first lens, f denotes an effective focal length of the optical lens, R11 denotes a radius of curvature of an object side surface of the first lens, and R12 denotes a radius of curvature of an image side surface of the first lens. The surface type and the focal length of the first lens can be reasonably controlled by satisfying the conditional expressions (2) and (3), so that the aperture of the subsequent lens is favorably reduced, and the volume miniaturization of the optical lens is realized.

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

0.3<IH/(f×tanθ)<0.4；（4）

wherein f represents an effective focal length of the optical lens, θ represents a maximum half field angle of the optical lens, and IH represents an image height corresponding to the maximum half field angle of the optical lens. And the conditional expression (4) is met, so that the optical lens is ensured to have a large field angle, and the miniaturization of the lens is realized.

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

1.1<IH/f<1.8；（5）

wherein f represents an effective focal length of the optical lens, and IH represents an image height corresponding to a maximum half field angle of the optical lens. The optical lens satisfies the conditional expression (5), and is favorable for realizing the small head characteristic while having good imaging quality.

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

0.45<DM11/IH<0.7；（6）

where DM11 denotes an effective half aperture of an object-side surface of the first lens, and IH denotes an image height corresponding to a maximum half field angle of the optical lens. The aperture size of the first lens can be reasonably controlled by satisfying the conditional expression (6), and the balance of the small head characteristic and the large wide-angle field of view of the optical lens can be favorably realized.

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

1<R41/f<6；（7）

-10<R41/R42<-1；（8）

where f denotes an effective focal length of the optical lens, R41 denotes a radius of curvature of an object-side surface of the fourth lens, and R42 denotes a radius of curvature of an image-side surface of the fourth lens. The surface type of the fourth lens can be reasonably controlled by satisfying the conditional expressions (7) and (8), the turning trend of light rays is slowed down, and the optical distortion of the optical lens is favorably corrected.

0.4<R52/DM52<0.8；（9）

wherein R52 represents a radius of curvature of an image-side surface of the fifth lens, and DM52 represents an effective half aperture of the image-side surface of the fifth lens. The formula (9) is satisfied, the surface shape of the fifth lens can be reasonably controlled, the difficulty in lens forming and lens assembly is reduced, and the production yield of the optical lens is improved.

-0.35<f5/f6<0；（10）

where f5 denotes a focal length of the fifth lens, and f6 denotes a focal length of the sixth lens. The condition formula (10) is met, the imaging quality of the lens in the on-axis field area can be effectively improved by reasonably controlling the focal length ratio of the fifth lens and the sixth lens, and the overall resolving power is improved.

0.18<CT4/TTL<0.25；（11）

wherein, CT4 represents the center thickness of the fourth lens, and TTL represents the total optical length of the optical lens. Satisfying the conditional expression (11), the fourth lens has a proper central thickness, which can slow down the turning of light and is beneficial to correcting the aberration brought by the front lens.

0.7<TTL/(f×tanθ)<0.9；（12）

wherein f represents the effective focal length of the optical lens, theta represents the maximum half field angle of the optical lens, and TTL represents the total optical length of the optical lens. Satisfying the conditional expression (12), the miniaturization and wide-angle balance of the lens can be realized better, and a wider shooting range is realized.

0.8<f12/f <3；（13）

wherein f represents an effective focal length of the optical lens, and f12 represents a combined focal length of the first lens and the second lens. The combined focal power of the first lens and the second lens can be reasonably controlled to achieve the purpose of converging light rays when the conditional expression (13) is met, so that the total length of the system is reduced, overlarge aberration is avoided, and the miniaturization of the lens and the balance of high pixels are better realized.

0.8<(SAG32-SAG31)/SAG32<2.5；（14）

SAG31 represents an on-axis distance from an intersection point of an object side surface of the third lens and an optical axis to a maximum effective semi-caliber vertex of the object side surface of the third lens, and SAG32 represents an on-axis distance from an intersection point of an image side surface of the third lens and the optical axis to the maximum effective semi-caliber vertex of the image side surface of the third lens. And the vector height can be reasonably distributed and the shape of the third lens can be controlled when the conditional expression (14) is met, so that the requirement on system manufacturability is favorably met and the production yield of the optical lens is improved.

0.02<N6/V6<0.1；（15）

where N6 denotes a refractive index of the sixth lens, and V6 denotes an abbe number of the sixth lens. And the conditional expression (15) is satisfied, so that the system chromatic aberration is favorably reduced.

As an implementation mode, a full plastic lens can be adopted, and glass and plastic can be mixed and matched, so that a good imaging effect can be achieved; in this application, for volume, weight and the reduce cost of better reduction camera lens, adopt six plastic lens combinations, through specific surface shape collocation and reasonable focal power distribution for distortion and aberration are effectively corrected when optical lens has super large visual angle, are favorable to improving the resolving power of camera lens, provide the optical property product of higher performance-price ratio, satisfied the frivolous, wide-angle user demand of portable electronic equipment simultaneously better.

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

In the embodiments of the present invention, when the lenses in the optical lens are aspheric lenses, the aspheric surface types of the lenses all satisfy the following equation:

wherein z represents the height of the distance from the aspheric surface to the aspheric surface vertex in the optical axis direction at the position of height h, c is the paraxial curvature of the surface, k is a quadric coefficient, A _2i Is the aspheric surface type coefficient of 2i order.

First embodiment

As shown in fig. 1, which is a schematic structural diagram of an optical lens 100 according to a first embodiment of the present invention, the optical lens 100 sequentially includes, from an object side to an image plane S15 along an optical axis: a first lens L1, an aperture stop ST, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a filter G1.

Wherein the first lens element L1 has a negative power, the object-side surface S1 of the first lens element is concave at the paraxial region, and the image-side surface S2 of the first lens element is concave;

the second lens L2 has positive focal power, the object side surface S3 of the second lens is a convex surface, and the image side surface S4 of the second lens is a convex surface;

the third lens element L3 has negative optical power, and has a convex object-side surface S5 at paraxial region and a concave image-side surface S6;

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

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

the sixth lens L6 has positive optical power, and an object-side surface S11 and an image-side surface S12 of the sixth lens are convex at paraxial regions.

The object-side surface of the filter G1 is S13, and the image-side surface is S14.

The first lens element L1, the second lens element L2, the third lens element L3, the fourth lens element L4, the fifth lens element L5 and the sixth lens element L6 are all plastic aspheric lenses.

Specifically, the design parameters of each lens of the optical lens 100 provided in this embodiment are shown in table 1.

TABLE 1

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

TABLE 2

In the present embodiment, graphs of curvature of field and vertical axis chromatic aberration of the optical lens 100 are shown in fig. 2 and 3, respectively.

The field curvature curve in fig. 2 indicates the degree of curvature of the meridional image plane and the sagittal image plane, and in fig. 2, the horizontal axis indicates the amount of displacement (unit: mm) and the vertical axis indicates the angle of view (unit: degree). As can be seen from fig. 2, the field curvature of the image plane in the meridional and sagittal directions is controlled within ± 0.1mm, which indicates that the field curvature correction of the optical lens 100 is good.

The vertical axis chromatic aberration curve in fig. 3 shows chromatic aberration at different image heights on the image forming plane for each wavelength with respect to the center wavelength (0.555 μm), the horizontal axis in fig. 3 shows the vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis shows the normalized angle of view. As can be seen from fig. 3, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ± 3 μm, which indicates that the optical lens 100 can effectively correct the aberration of the fringe field and the secondary spectrum of the entire image plane.

Second embodiment

As shown in fig. 4, which is a schematic structural diagram of an optical lens 200 according to the present embodiment, the structure of the optical lens 200 in the present embodiment is substantially the same as that of the optical lens 100 in the first embodiment, except that the image-side surface S12 of the sixth lens element is concave at the paraxial region, and the curvature radius, aspheric coefficient, thickness and material of each lens surface type are different.

The parameters related to each lens in the optical lens 200 provided in this embodiment are shown in table 3.

TABLE 3

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

TABLE 4

In the present embodiment, graphs of curvature of field and vertical axis chromatic aberration of the optical lens 200 are shown in fig. 5 and 6, respectively. As can be seen from fig. 5, the field curvature of the meridional image plane and the sagittal image plane is controlled within ± 0.05mm, which indicates that the field curvature correction of the optical lens 200 is good. As can be seen from fig. 6, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ± 3 μm, which indicates that the optical lens 200 can effectively correct the aberration of the fringe field and the secondary spectrum of the entire image plane.

Third embodiment

As shown in fig. 7, a schematic structural diagram of an optical lens 300 according to the present embodiment is provided, and the structure of the optical lens 300 in the present embodiment is substantially the same as that of the optical lens 100 in the first embodiment, except that the image-side surface S12 of the sixth lens element is concave at the paraxial region, and the curvature radius, aspheric coefficient, thickness and material of each lens surface type are different.

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

TABLE 5

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

TABLE 6

In the present embodiment, graphs of curvature of field and vertical axis chromatic aberration of the optical lens 300 are shown in fig. 8 and 9, respectively. As can be seen from fig. 8, the field curvature of the meridional image plane and the sagittal image plane is controlled within ± 0.05mm, which indicates that the field curvature of the optical lens 300 is well corrected. As can be seen from fig. 9, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ± 1.5 μm, which indicates that the optical lens 300 can effectively correct the aberration of the fringe field and the secondary spectrum of the entire image plane.

Table 7 shows the optical characteristics corresponding to the three embodiments, which mainly includes the maximum field angle 2 θ of the optical lens, the image height IH corresponding to the maximum half field angle, the effective focal length f, the total optical length TTL (the distance from the object-side surface of the first lens to the image plane on the optical axis), and the numerical values corresponding to each of the above conditional expressions.

TABLE 7

In summary, the optical lens provided by the embodiments of the present invention has at least the following advantages:

(1) The optical lens has a field angle of over 150 degrees, can effectively correct distortion, and can meet the requirements of large field angle and high-definition imaging.

(2) The optical lens adopts six lens structures with specific focal power, and all the lenses are matched through specific surface shapes, so that the total lens length (TTL <4.8 mm) is effectively shortened, the outer diameter of the head of the lens is reduced, the miniaturization of the lens is realized, and the use requirements of portable intelligent electronic products can be better met.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. An optical lens, comprising, in order from an object side to an image plane along an optical axis:

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

a diaphragm;

a second lens having a positive optical power, the second lens having both an object-side surface and an image-side surface that are convex;

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

a fourth lens having positive optical power, the fourth lens having both an object-side surface and an image-side surface that are convex;

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

a sixth lens having positive optical power, an object side surface of the sixth lens being convex at a paraxial region;

the optical lens comprises at least one aspheric lens.

2. An optical lens according to claim 1, wherein the optical lens satisfies the conditional expression:

0<f/f6<0.2；

wherein f6 denotes a focal length of the sixth lens, and f denotes an effective focal length of the optical lens.

3. An optical lens according to claim 1, wherein the optical lens satisfies the conditional expression:

-2<f1/f<-1；

-15<R11/R12<-1；

where f1 denotes a focal length of the first lens, f denotes an effective focal length of the optical lens, R11 denotes a radius of curvature of an object side surface of the first lens, and R12 denotes a radius of curvature of an image side surface of the first lens.

4. An optical lens according to claim 1, wherein the optical lens satisfies the conditional expression:

0.3<IH/(f×tanθ)<0.4；

wherein f represents an effective focal length of the optical lens, θ represents a maximum half field angle of the optical lens, and IH represents an image height corresponding to the maximum half field angle of the optical lens.

5. An optical lens according to claim 1, wherein the optical lens satisfies the conditional expression:

1.1<IH/f<1.8；

wherein f represents an effective focal length of the optical lens, and IH represents an image height corresponding to a maximum half field angle of the optical lens.

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

0.45<DM11/IH<0.7；

where DM11 denotes an effective half aperture of an object-side surface of the first lens, and IH denotes an image height corresponding to a maximum half field angle of the optical lens.

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

1<R41/f<6；

-10<R41/R42<-1；

where f denotes an effective focal length of the optical lens, R41 denotes a radius of curvature of an object-side surface of the fourth lens, and R42 denotes a radius of curvature of an image-side surface of the fourth lens.

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

0.4<R52/DM52<0.8；

wherein R52 represents a radius of curvature of an image-side surface of the fifth lens, and DM52 represents an effective half aperture of the image-side surface of the fifth lens.

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

-0.35<f5/f6<0；

where f5 denotes a focal length of the fifth lens, and f6 denotes a focal length of the sixth lens.

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

0.18<CT4/TTL<0.25；

wherein, CT4 represents the center thickness of the fourth lens, and TTL represents the total optical length of the optical lens.

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

0.7<TTL/(f×tanθ)<0.9；

wherein f represents the effective focal length of the optical lens, theta represents the maximum half field angle of the optical lens, and TTL represents the total optical length of the optical lens.