CN113885173A

CN113885173A - Optical imaging lens

Info

Publication number: CN113885173A
Application number: CN202111212339.4A
Authority: CN
Inventors: 龙思琛; 徐武超; 国成立; 戴付建; 赵烈烽
Original assignee: Zhejiang Sunny Optics Co Ltd
Current assignee: Zhejiang Sunny Optics Co Ltd
Priority date: 2021-10-18
Filing date: 2021-10-18
Publication date: 2022-01-04
Anticipated expiration: 2041-10-18
Also published as: CN113885173B

Abstract

The invention provides an optical imaging lens, which sequentially comprises the following components from an object side to an image side of the optical imaging lens along an optical axis of the optical imaging lens: the first lens has positive focal power, and the object side surface of the first lens is a convex surface; a diffractive optical element having a diffraction efficiency of greater than 80% for light having a wavelength in the range of 470nm to 650 nm; the second lens has negative focal power, and the image side surface of the second lens is a concave surface; a third lens having a positive focal power; the fourth lens has negative focal power, the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a concave surface; the effective focal length f of the optical imaging lens and the axial distance TTL from the object side surface of the first lens to the imaging surface of the optical imaging lens satisfy 15mm<f²/TTL<17 mm. The invention solves the problem that the optical imaging lens in the prior art cannot give consideration to high imaging quality and miniaturization.

Description

Optical imaging lens

Technical Field

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

Background

With the rapid development of portable intelligent photographing devices such as smart phones, photographing functions with high imaging quality are increasingly favored by consumers. The chromatic aberration is an important factor affecting the imaging quality, and is usually corrected by adopting a positive and negative lens combination mode. According to the method, the number of lenses of the imaging lens is increased while the chromatic aberration is optimized and the imaging quality is improved, so that the ultra-thinning of the imaging lens is limited.

That is to say, the optical imaging lens in the prior art has the problem that the high imaging quality and the miniaturization can not be compatible.

Disclosure of Invention

The invention mainly aims to provide an optical imaging lens, which solves the problem that the optical imaging lens in the prior art cannot give consideration to high imaging quality and miniaturization.

In order to achieve the above object, according to one aspect of the present invention, there is provided an optical imaging lens comprising, in order from an object side to an image side of the optical imaging lens along an optical axis of the optical imaging lens: the first lens has positive focal power, and the object side surface of the first lens is a convex surface; a diffractive optical element having a diffraction efficiency of greater than 80% for light having a wavelength in the range of 470nm to 650 nm; the second lens has negative focal power, and the image side surface of the second lens is a concave surface; a third lens having a positive focal power; the fourth lens has negative focal power, the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a concave surface; the effective focal length f of the optical imaging lens and the axial distance TTL from the object side surface of the first lens to the imaging surface of the optical imaging lens satisfy 15mm<f²/TTL<17mm。

Further, the effective focal length f1 of the first lens and the curvature radius R1 of the object side surface of the first lens satisfy: 1.4< f1/R1< 2.0.

Further, the effective focal length f4 of the fourth lens and the effective focal length f2 of the second lens satisfy: 0.8< f4/f2< 1.5.

Further, the effective focal length f3 of the third lens and the ImgH which is half the diagonal length of the effective pixel area on the imaging plane satisfy: 4.6< f3/ImgH < 5.6.

Further, a radius of curvature R7 of the object-side surface of the fourth lens and a radius of curvature R8 of the image-side surface of the fourth lens satisfy: 2.4< (R7+ R8)/(R7-R8) < 3.4.

Further, the central thickness CT1 of the first lens, the central thickness CT2 of the second lens, the central thickness CT3 of the third lens, and the central thickness CT4 of the fourth lens satisfy: 1.0< CT1/(CT2+ CT3+ CT4) < 1.8.

Further, an on-axis distance BFL from the image-side surface of the fourth lens to the imaging surface, and an air interval T23 on the optical axis between the second lens and the third lens satisfy: 1.2< BFL/T23< 1.8.

Further, the combined focal length f34 of the third lens and the fourth lens and the combined focal length f12 of the first lens and the second lens satisfy the following conditions: -2.8< f34/f12< -2.0.

Further, the edge thickness ET1 of the first lens, the edge thickness ET3 of the third lens and the edge thickness ET4 of the fourth lens satisfy: 0.4< ET1/(ET3+ ET4) < 1.3.

Further, the maximum field angle FOV of the optical imaging lens satisfies: 15 ° < FOV <25 °.

Further, diffraction optical element is double-deck diffraction optical element, and diffraction optical element is including stratum basale, first glue film and the second glue film that sets gradually, and first glue film has a plurality of concentric ring gear structures, and the center of a plurality of ring gear structures is the optical axis, and first glue film and the laminating of second glue film set up, and clearance d between first glue film and the second glue film satisfies: d is less than 1 μm.

According to another aspect of the present invention, there is provided an optical imaging lens, comprising in order from an object side to an image side of the optical imaging lens along an optical axis of the optical imaging lens: the first lens has positive focal power, and the object side surface of the first lens is a convex surface; a diffractive optical element having a diffraction efficiency of greater than 80% for light having a wavelength in the range of 470nm to 650 nm; the second lens has negative focal power, and the image side surface of the second lens is a concave surface; a third lens having a positive focal power; the fourth lens has negative focal power, the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a concave surface; the central thickness CT1 of the first lens, the central thickness CT2 of the second lens, the central thickness CT3 of the third lens and the central thickness CT4 of the fourth lens satisfy: 1.0< CT1/(CT2+ CT3+ CT4) < 1.8.

With the technical solution of the present invention, the imaging lens sequentially includes, from an object side to an image side of the imaging lens along an optical axis of the imaging lens: the optical lens comprises a first lens, a diffractive optical element, a second lens, a third lens and a fourth lens, wherein the first lens has positive focal power, and the object side surface of the first lens is a convex surface; a diffraction efficiency of the diffractive optical element for light having a wavelength in a range of 470nm to 650nm is greater than 80%; the second lens has negative focal power, and the image side surface of the second lens is a concave surface; the third lens has positive focal power; the fourth lens has negative focal power, the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a concave surface; the effective focal length f of the optical imaging lens and the axial distance TTL from the object side surface of the first lens to the imaging surface of the optical imaging lens satisfy 15mm<f²/TTL<17mm。

Through reasonable design of focal power and surface type of each lens, each aspheric surface coefficient of each lens is reasonably distributed, monochromatic aberration of an optical system is corrected, the aberration generated by each lens is favorably counteracted, and the imaging quality of the optical imaging lens is improved. The focal power of each lens is reasonably distributed, and the chromatic aberration generated by the lens group can be corrected by the diffractive optical element. The diffractive optical element can balance normal dispersion generated by the refractive lens group due to the capability of anomalous dispersion. By mixing f²the/TTL is controlled in a reasonable range, and the long-focus characteristic and the ultrathin characteristic of the optical imaging lens can be ensured.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic structural view of an optical imaging lens according to a first example of the present invention;

fig. 2 to 3 respectively show axial chromatic aberration curves and ordinary diffraction modulation transfer functions of the optical imaging lens in fig. 1;

fig. 4 is a schematic configuration diagram showing an optical imaging lens according to a second example of the present invention;

fig. 5 to 6 show axial chromatic aberration curves and ordinary diffraction modulation transfer functions of the optical imaging lens in fig. 4, respectively;

fig. 7 is a schematic configuration diagram showing an optical imaging lens according to a third example of the present invention;

fig. 8 to 9 respectively show axial chromatic aberration curves and ordinary diffraction modulation transfer functions of the optical imaging lens in fig. 7;

fig. 10 is a schematic configuration diagram showing an optical imaging lens according to example four of the present invention;

fig. 11 to 12 show axial chromatic aberration curves and ordinary diffraction modulation transfer functions of the optical imaging lens in fig. 10, respectively;

fig. 13 is a schematic configuration diagram showing an optical imaging lens according to example five of the present invention;

fig. 14 to 15 show axial chromatic aberration curves and ordinary diffraction modulation transfer functions of the optical imaging lens in fig. 13, respectively;

FIG. 16 shows a schematic structural diagram of a diffractive optical element according to an alternative embodiment of the present invention;

fig. 17 shows a schematic diagram of the relationship between the diffractive optical element and the design wavelength of the optical imaging lens.

Wherein the figures include the following reference numerals:

10. a substrate, 20 and a first adhesive layer; 30. a second adhesive layer; STO, stop; e1, first lens; s1, the object side surface of the first lens; s2, an image side surface of the first lens; e2, second lens; s3, the object side surface of the second lens; s4, an image side surface of the second lens; e3, third lens; s5, the object side surface of the third lens; s6, an image side surface of the third lens; e4, fourth lens; s7, the object side surface of the fourth lens; s8, an image side surface of the fourth lens element; e5, a filter plate; s9, the object side surface of the filter plate; s10, the image side surface of the filter plate; s11, imaging surface; DOE, diffractive optical element.

Detailed Description

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 invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

It is noted that, unless otherwise indicated, 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 application belongs.

In the present invention, unless specified to the contrary, use of the terms of orientation such as "upper, lower, top, bottom" or the like, generally refer to the orientation as shown in the drawings, or to the component itself in a vertical, perpendicular, or gravitational orientation; likewise, for ease of understanding and description, "inner and outer" refer to the inner and outer relative to the profile of the components themselves, but the above directional words are not intended to limit the invention.

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 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 close to the object side becomes the object side surface of the lens, and the surface of each lens close to the image side is called the image side surface of the lens. The determination of the surface shape in the paraxial region can be performed by determining whether or not the surface shape is concave or convex, based on the R value (R denotes the radius of curvature of the paraxial region, and usually denotes the R value in a lens database (lens data) in optical software) in accordance with the determination method of a person ordinarily skilled in the art. For the object side surface, when the R value is positive, the object side surface is judged to be convex, and when the R value is negative, the object side surface is judged to be concave; in the case of the image side surface, the image side surface is determined to be concave when the R value is positive, and is determined to be convex when the R value is negative.

The invention provides an optical imaging lens, aiming at solving the problem that the optical imaging lens in the prior art cannot give consideration to high imaging quality and miniaturization.

With the popularization and rapid development of smart phones, consumers increasingly demand miniaturization, ultra-thinness, and high imaging quality of mobile phones. Chromatic aberration, which is an important aberration affecting the imaging quality, is generally caused by different refractive indexes of optical materials for different color lights, and can be corrected by selecting a proper positive and negative lens combination. The diffractive optical element has strong anomalous dispersion characteristics, can replace a negative lens to effectively compensate chromatic aberration generated by the converging lens group, and improves the imaging quality of the lens. In order to meet the application requirement of further improving the imaging quality of the ultrathin imaging lens, the application provides a long-focus optical system comprising a double-layer diffraction optical element. Compared with a single-layer diffraction optical element, materials on two sides of a diffraction surface of the double-layer diffraction optical element are different, and the double-layer diffraction optical element is ensured to have better processing and forming characteristics and diffraction efficiency by selecting proper material matching.

Example one

As shown in fig. 1 to 17, the optical imaging lens includes, in order from an object side to an image side of the optical imaging lens, a first lens, a diffractive optical element, a second lens, a third lens and a fourth lens, the first lens having positive optical power, and an object side surface of the first lens being a convex surface; a diffraction efficiency of the diffractive optical element for light having a wavelength in a range of 470nm to 650nm is greater than 80%; the second lens has negative focal power, and the image side surface of the second lens is a concave surface; the third lens has positive focal power; the fourth lens has negative focal power, the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a concave surface; the effective focal length f of the optical imaging lens and the axial distance TTL from the object side surface of the first lens to the imaging surface of the optical imaging lens satisfy 15mm<f²/TTL<17mm。

By aiming at eachThe focal power and the surface type of each lens are reasonably designed, various aspheric coefficients of each lens are reasonably distributed, and the monochromatic aberration of an optical system is corrected, so that the aberration generated by each lens can be offset, and the imaging quality of the optical imaging lens is improved. The focal power of each lens is reasonably distributed, and the chromatic aberration generated by the lens group can be corrected by the diffractive optical element. The diffractive optical element can balance normal dispersion generated by the refractive lens group due to the capability of anomalous dispersion. By mixing f²the/TTL is controlled in a reasonable range, and the long-focus characteristic and the ultrathin characteristic of the optical imaging lens can be ensured.

Preferably, the effective focal length f of the optical imaging lens and the on-axis distance TTL from the object side surface of the first lens to the imaging surface of the optical imaging lens satisfy 16mm<f²/TTL<16.7mm。

In the present embodiment, the effective focal length f1 of the first lens and the radius of curvature R1 of the object side surface of the first lens satisfy: 1.4< f1/R1< 2.0. By limiting f1/R1 within a reasonable range, the processability of the first lens can be ensured, and the difficulty in processing and assembling the first lens can be reduced. Preferably, 1.45< f1/R1< 1.95.

In the present embodiment, the effective focal length f4 of the fourth lens and the effective focal length f2 of the second lens satisfy: 0.8< f4/f2< 1.5. By limiting f4/f2 within a reasonable range, the powers of the second lens and the fourth lens can be reasonably distributed, the contribution of the second lens and the fourth lens to chromatic aberration is controlled, and the aberration of the optical imaging lens is reduced. Preferably 0.9< f4/f2< 1.3.

In the present embodiment, the effective focal length f3 of the third lens and ImgH which is half the diagonal length of the effective pixel area on the imaging plane satisfy: 4.6< f3/ImgH < 5.6. By limiting f3/ImgH within a reasonable range, the aberration of the optical imaging lens is reduced, and the imaging quality of the optical imaging lens is ensured. Preferably 4.8< f3/ImgH < 5.4.

In the present embodiment, a radius of curvature R7 of the object-side surface of the fourth lens and a radius of curvature R8 of the image-side surface of the fourth lens satisfy: 2.4< (R7+ R8)/(R7-R8) < 3.4. By limiting (R7+ R8)/(R7-R8) to a reasonable range, the radius of curvature of the object-side surface of the fourth lens and the radius of curvature of the image-side surface of the fourth lens can be controlled to a reasonable range, the amount of contribution of astigmatism between the object-side surface of the fourth lens and the image-side surface of the fourth lens can be effectively controlled, and the image quality of the intermediate field and the aperture zone can be effectively and reasonably controlled. Preferably, 2.5< (R7+ R8)/(R7-R8) < 3.3.

In the present embodiment, the center thickness CT1 of the first lens, the center thickness CT2 of the second lens, the center thickness CT3 of the third lens, and the center thickness CT4 of the fourth lens satisfy: 1.0< CT1/(CT2+ CT3+ CT4) < 1.8. By controlling CT1/(CT2+ CT3+ CT4) within a reasonable range, the manufacturing and molding of the first lens, the second lens, the third lens and the fourth lens are facilitated, and the processing difficulty of the lenses is reduced. Preferably, 1.1< CT1/(CT2+ CT3+ CT4) < 1.7.

In this embodiment, an on-axis distance BFL from the image-side surface of the fourth lens to the imaging surface and an air interval T23 on the optical axis between the second lens and the third lens satisfy: 1.2< BFL/T23< 1.8. By controlling the BFL/T23 in a reasonable range, the layout of the whole space structure of the optical imaging lens is facilitated, and the assembly of the optical imaging lens is facilitated. Preferably, 1.3< BFL/T23< 1.7.

In the present embodiment, the combined focal length f34 of the third lens and the fourth lens and the combined focal length f12 of the first lens and the second lens satisfy: -2.8< f34/f12< -2.0. By limiting f34/f12 within a reasonable range, reasonable configuration of focal power is facilitated, aberration of the optical imaging lens is reduced, and imaging quality of the optical imaging lens is guaranteed. Preferably, -2.7< f34/f12< -2.1.

In the present embodiment, the edge thicknesses ET1, ET3 and ET4 of the first lens, the third lens and the fourth lens satisfy: 0.4< ET1/(ET3+ ET4) < 1.3. Through the edge thickness of the first lens, the third lens and the fourth lens which are reasonably controlled, the lens processability is ensured, and meanwhile, the layout of a reasonable space structure of the optical imaging lens is favorably realized. Preferably, 0.5< ET1/(ET3+ ET4) < 1.2.

In the present embodiment, the maximum field angle FOV of the optical imaging lens satisfies: 15 ° < FOV <25 °. The maximum field angle range of the optical imaging lens is reasonably controlled, so that the long-focus characteristic of the optical imaging lens is favorably ensured, and the optical imaging lens can realize long-focus shooting. Preferably 18 ° < FOV <23 °.

In this embodiment, the diffractive optical element is a double-layer diffractive optical element, the diffractive optical element includes the basal layer 10, the first glue layer 20 and the second glue layer 30 that set gradually, the first glue layer 20 has a plurality of concentric ring gear structures, the center of a plurality of ring gear structures is the optical axis, the first glue layer 20 and the second glue layer 30 are laminated and set, and the clearance d between the first glue layer 20 and the second glue layer 30 satisfies: d is less than 1 μm. The diffraction optical element has strong anomalous dispersion, can correct the normal dispersion generated by the lens group and improve the imaging quality of the optical imaging lens. The diffraction efficiency of the diffraction optical element is improved by reasonably selecting the materials of the two layers of photoresist.

Example two

As shown in fig. 1 to 17, the optical imaging lens sequentially includes, from an object side to an image side of the optical imaging lens along an optical axis of the optical imaging lens: the optical lens comprises a first lens, a diffractive optical element, a second lens, a third lens and a fourth lens, wherein the first lens has positive focal power, and the object side surface of the first lens is a convex surface; a diffraction efficiency of the diffractive optical element for light having a wavelength in a range of 470nm to 650nm is greater than 80%; the second lens has negative focal power, and the image side surface of the second lens is a concave surface; the third lens has positive focal power; the fourth lens has negative focal power, the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a concave surface; the central thickness CT1 of the first lens, the central thickness CT2 of the second lens, the central thickness CT3 of the third lens and the central thickness CT4 of the fourth lens satisfy: 1.0< CT1/(CT2+ CT3+ CT4) < 1.8.

Through reasonable design of focal power and surface type of each lens, each aspheric surface coefficient of each lens is reasonably distributed, monochromatic aberration of an optical system is corrected, the aberration generated by each lens is favorably counteracted, and the imaging quality of the optical imaging lens is improved. The focal power of each lens is reasonably distributed, and the chromatic aberration generated by the lens group can be corrected by the diffractive optical element. The diffractive optical element can balance normal dispersion generated by the refractive lens group due to the capability of anomalous dispersion. By controlling CT1/(CT2+ CT3+ CT4) within a reasonable range, the manufacturing and molding of the first lens, the second lens, the third lens and the fourth lens are facilitated, and the processing difficulty of the lenses is reduced.

Preferably, the central thickness CT1 of the first lens, the central thickness CT2 of the second lens, the central thickness CT3 of the third lens and the central thickness CT4 of the fourth lens satisfy: 1.1< CT1/(CT2+ CT3+ CT4) < 1.7.

Optionally, the optical imaging lens may further include a filter for correcting color deviation and/or a protective glass for protecting a photosensitive element on the imaging surface.

The optical imaging lens in the present application may employ a plurality of lenses, for example, four lenses as described above. By reasonably distributing the focal power, the surface shape, the central thickness of each lens, the axial distance between each lens and the like, the aperture of the optical imaging lens can be effectively increased, the sensitivity of the lens can be reduced, and the machinability of the lens can be improved, so that the optical imaging lens is more beneficial to production and processing and can be suitable for portable electronic equipment such as smart phones. The optical imaging lens also has large aperture and large field angle. The advantages of ultra-thin and good imaging quality can meet the miniaturization requirement of intelligent electronic products.

In the present application, at least one of the mirror surfaces of each lens is an aspherical mirror surface. The aspheric lens is characterized in that: the curvature varies continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has better curvature radius characteristics, and has advantages of improving distortion aberration and improving astigmatic aberration. After the aspheric lens is adopted, the aberration generated during imaging can be eliminated as much as possible, thereby improving the imaging quality.

However, it will be appreciated by those skilled in the art that the number of lenses constituting an optical imaging lens 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 four lenses are exemplified in the embodiment, the optical imaging lens is not limited to including four lenses. The optical imaging lens may also include other numbers of lenses, as desired.

Examples of specific surface types and parameters of the optical lens group applicable to the above embodiments are further described below with reference to the drawings.

It should be noted that any one of the following examples one to five is applicable to all embodiments of the present application.

Example one

As shown in fig. 1 to 3, an optical imaging lens of the first example of the present application is described. Fig. 1 shows a schematic diagram of an optical imaging lens structure of example one.

As shown in fig. 1, the optical imaging lens includes, in order from an object side to an image side: a stop STO, a first lens E1, a diffractive optical element DOE, a second lens E2, a third lens E3, a fourth lens E4, a filter E5, and an image plane S11.

The first lens element E1 has positive refractive power, and the object-side surface S1 and the image-side surface S2 of the first lens element are convex. The second lens E2 has negative power, and the object-side surface S3 of the second lens is concave, and the image-side surface S4 of the second lens is concave. The third lens element E3 has positive refractive power, and the object-side surface S5 and the image-side surface S6 of the third lens element are convex. The fourth lens element E4 has negative power, and the object-side surface S7 of the fourth lens element is convex and the image-side surface S8 of the fourth lens element is concave. Filter E5 has an object side S9 and an image side S10 of the filter. The light from the object sequentially passes through the respective surfaces S1 to S10 and is finally imaged on the imaging surface S11.

In this example, the total effective focal length f of the optical imaging lens is 14.41mm, the total length TTL of the optical imaging lens is 12.73mm, and the image height ImgH is 2.71 mm.

Table 1 shows a basic structural parameter table of the optical imaging lens of example one, in which the units of the radius of curvature, the thickness/distance, the focal length, and the effective radius are all millimeters (mm).

TABLE 1

In example one, the object-side surface and the image-side surface of any one of the first lens element E1 through the fourth lens element E4 are aspheric, and the surface shape of each aspheric lens can be defined by, but is not limited to, the following aspheric formula:

wherein x is the rise of the distance from the aspheric surface vertex to the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis direction; c is the paraxial curvature 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 a conic coefficient; ai is the correction coefficient of the i-th order of the aspherical surface. Table 2 below gives the high-order coefficient A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28, A30, which can be used for each of the aspherical mirrors S1-S10 in example one.

TABLE 2

Fig. 2 shows an on-axis chromatic aberration curve of the optical imaging lens of example one, which represents the deviation of the convergent focus of light rays of different wavelengths after passing through the optical imaging lens. Fig. 3 shows a general diffraction modulation transfer function of the optical imaging lens of example one, which represents the diffraction performance of the optical imaging lens.

As can be seen from fig. 2 and 3, the optical imaging lens according to the first example can achieve good imaging quality.

Example two

As shown in fig. 4 to 6, an optical imaging lens of example two of the present application is described. In this example and the following examples, descriptions of parts similar to example one will be omitted for the sake of brevity. Fig. 4 shows a schematic diagram of the optical imaging lens structure of example two.

As shown in fig. 4, the optical imaging lens includes, in order from an object side to an image side: a stop STO, a first lens E1, a diffractive optical element DOE, a second lens E2, a third lens E3, a fourth lens E4, a filter E5, and an image plane S11.

The first lens element E1 has positive refractive power, and the object-side surface S1 and the image-side surface S2 of the first lens element are convex. The second lens E2 has negative power, and the object-side surface S3 of the second lens is concave, and the image-side surface S4 of the second lens is concave. The third lens element E3 has positive refractive power, and the object-side surface S5 of the third lens element is convex, and the image-side surface S6 of the third lens element is concave. The fourth lens element E4 has negative power, and the object-side surface S7 of the fourth lens element is convex and the image-side surface S8 of the fourth lens element is concave. Filter E5 has an object side S9 and an image side S10 of the filter. The light from the object sequentially passes through the respective surfaces S1 to S10 and is finally imaged on the imaging surface S11.

In this example, the total effective focal length f of the optical imaging lens is 14.40mm, the total length TTL of the optical imaging lens is 12.73mm, and the image height ImgH is 2.71 mm.

Table 3 shows a basic structural parameter table of the optical imaging lens of example two, in which the units of the radius of curvature, the thickness/distance, the focal length, and the effective radius are all millimeters (mm).

TABLE 3

Table 4 shows the high-order term coefficients that can be used for each aspherical mirror surface in example two, wherein each aspherical mirror surface type can be defined by formula (1) given in example one above.

Flour mark

A4

A6

A8

A10

A12

A14

A16

S1

-4.3220E-02

-7.3985E-03

-1.5142E-03

-3.1631E-04

-2.1133E-05

3.5251E-06

-1.5779E-06

S2

2.5335E-02

-7.4257E-03

-1.6100E-03

2.9874E-05

1.4014E-04

-2.5268E-05

-5.3895E-06

S3

1.3603E-01

-1.0074E-02

-6.6370E-04

-3.5377E-05

2.1475E-04

-5.1316E-05

2.5093E-06

S4

9.6148E-02

-4.2999E-03

-1.2944E-04

-5.5680E-05

1.1855E-04

-2.2215E-05

-1.9869E-07

S5

-8.4389E-02

-5.3905E-03

-1.2069E-03

2.2771E-04

6.2735E-05

-6.8809E-06

-8.5672E-06

S6

-1.2285E-01

-2.0452E-04

-2.9535E-03

1.0821E-03

-4.0444E-05

-1.6193E-06

-1.2562E-05

S7

-3.7271E-01

4.2770E-02

-9.0294E-03

2.4543E-03

-4.1061E-04

2.5716E-05

-1.5329E-05

S8

-4.3252E-01

4.4624E-02

-9.7825E-03

2.3636E-03

-5.8666E-04

1.1279E-04

-7.3451E-06

Flour mark

A18

A20

A22

A24

A26

A28

A30

S1

-3.3623E-07

7.5643E-08

0.0000E+00

S2

2.2870E-06

-1.5913E-07

0.0000E+00

S3

2.1621E-07

1.7847E-07

0.0000E+00

S4

-3.0495E-07

2.1448E-07

8.8852E-08

0.0000E+00

S5

1.4185E-05

1.1681E-05

0.0000E+00

S6

5.1232E-05

2.0096E-05

-1.8521E-06

-1.1457E-06

-4.9918E-07

-4.9377E-07

0.0000E+00

S7

6.3992E-05

2.1126E-05

-7.4728E-07

0.0000E+00

S8

4.1063E-05

8.3431E-07

-1.5899E-06

0.0000E+00

TABLE 4

Fig. 5 shows an on-axis chromatic aberration curve of the optical imaging lens of example one, which represents the deviation of the convergent focus of light rays of different wavelengths after passing through the optical imaging lens. Fig. 6 shows a general diffraction modulation transfer function of the optical imaging lens of example one, which represents the diffraction performance of the optical imaging lens.

As can be seen from fig. 5 and 6, the optical imaging lens according to the first example can achieve good imaging quality.

Example III

As shown in fig. 7 to 9, an optical imaging lens of example three of the present application is described. Fig. 7 shows a schematic diagram of an optical imaging lens structure of example three.

As shown in fig. 7, the optical imaging lens includes, in order from an object side to an image side: a stop STO, a first lens E1, a diffractive optical element DOE, a second lens E2, a third lens E3, a fourth lens E4, a filter E5, and an image plane S11.

The first lens element E1 has positive refractive power, and the object-side surface S1 and the image-side surface S2 of the first lens element are convex. The second lens element E2 has negative power, and the object-side surface S3 of the second lens element is convex and the image-side surface S4 of the second lens element is concave. The third lens element E3 has positive refractive power, and the object-side surface S5 and the image-side surface S6 of the third lens element are convex. The fourth lens element E4 has negative power, and the object-side surface S7 of the fourth lens element is convex and the image-side surface S8 of the fourth lens element is concave. Filter E5 has an object side S9 and an image side S10 of the filter. The light from the object sequentially passes through the respective surfaces S1 to S10 and is finally imaged on the imaging surface S11.

In this example, the total effective focal length f of the optical imaging lens is 14.40mm, the total length TTL of the optical imaging lens is 12.70mm, and the image height ImgH is 2.71 mm.

Table 5 shows a basic structural parameter table of the optical imaging lens of example three, in which the units of the radius of curvature, thickness/distance, focal length, and effective radius are all millimeters (mm).

TABLE 5

Table 6 shows the high-order term coefficients that can be used for each aspherical mirror surface in example three, wherein each aspherical mirror surface type can be defined by formula (1) given in example one above.

Flour mark

A4

A6

A8

A10

A12

A14

A16

S1

-4.5781E-02

-7.0912E-03

-1.4129E-03

-3.2481E-04

-2.7858E-05

2.3898E-06

-1.1764E-06

S2

2.6543E-02

-7.6392E-03

-1.5313E-03

-3.3162E-05

1.4789E-04

-2.8478E-05

-3.0352E-06

S3

1.3316E-01

-1.0179E-02

-1.1198E-03

-8.1397E-05

2.6319E-04

-6.0015E-05

3.4697E-06

S4

9.6423E-02

-3.7121E-03

-4.6359E-04

-1.0247E-04

1.4576E-04

-2.2546E-05

-1.2630E-06

S5

-8.4919E-02

-7.9991E-03

-5.0376E-04

3.6032E-05

4.1739E-05

-4.7507E-06

1.1740E-05

S6

-1.1693E-01

-1.2972E-04

-2.1403E-03

9.0497E-04

-2.0390E-04

6.5511E-06

-1.0817E-05

S7

-3.6883E-01

4.6795E-02

-8.7685E-03

2.2778E-03

-5.0314E-04

8.3132E-06

-4.3815E-05

S8

-4.3660E-01

4.5746E-02

-9.5223E-03

2.0822E-03

-5.1734E-04

7.1435E-05

-1.2258E-05

Flour mark

A18

A20

A22

A24

A26

A28

A30

S1

-4.5205E-07

5.6587E-08

0.0000E+00

S2

1.6192E-06

-1.0634E-07

0.0000E+00

S3

-2.1204E-07

4.5849E-07

0.0000E+00

S4

-8.3731E-07

3.2996E-07

-1.5244E-07

0.0000E+00

S5

2.3424E-05

1.3899E-05

0.0000E+00

S6

6.1367E-05

1.6856E-05

-6.4723E-06

-7.1791E-07

-4.1388E-07

-7.1769E-08

0.0000E+00

S7

6.1797E-05

2.0360E-05

-7.2977E-06

0.0000E+00

S8

3.6418E-05

2.6563E-06

-5.3954E-06

0.0000E+00

TABLE 6

Fig. 8 shows a chromatic aberration curve on the axis of the optical imaging lens of example three, which represents the deviation of the convergent focus of light rays of different wavelengths after passing through the optical imaging lens. Fig. 9 shows a general diffraction modulation transfer function of the optical imaging lens of example three, which represents the diffraction performance of the optical imaging lens.

As can be seen from fig. 8 and 9, the optical imaging lens according to the third example can achieve good imaging quality.

Example four

As shown in fig. 10 to 12, an optical imaging lens of example four of the present application is described. Fig. 10 shows a schematic diagram of an optical imaging lens structure of example four.

As shown in fig. 10, the optical imaging lens includes, in order from an object side to an image side: a stop STO, a first lens E1, a diffractive optical element DOE, a second lens E2, a third lens E3, a fourth lens E4, a filter E5, and an image plane S11.

The first lens element E1 has positive refractive power, and the object-side surface S1 and the image-side surface S2 of the first lens element are convex. The second lens element E2 has negative power, and the object-side surface S3 of the second lens element is convex and the image-side surface S4 of the second lens element is concave. The third lens element E3 has positive refractive power, and the object-side surface S5 of the third lens element is concave, and the image-side surface S6 of the third lens element is convex. The fourth lens element E4 has negative power, and the object-side surface S7 of the fourth lens element is convex and the image-side surface S8 of the fourth lens element is concave. Filter E5 has an object side S9 and an image side S10 of the filter. The light from the object sequentially passes through the respective surfaces S1 to S10 and is finally imaged on the imaging surface S11.

In this example, the total effective focal length f of the optical imaging lens is 14.40mm, the total length TTL of the optical imaging lens is 12.69mm, and the image height ImgH is 2.71 mm.

Table 7 shows a basic structural parameter table of the optical imaging lens of example four, in which the units of the radius of curvature, the thickness/distance, the focal length, and the effective radius are all millimeters (mm).

TABLE 7

Table 8 shows the high-order term coefficients that can be used for each aspherical mirror surface in example four, wherein each aspherical mirror surface type can be defined by formula (1) given in example one above.

Flour mark

A4

A6

A8

A10

A12

A14

A16

S1

-4.4649E-02

-7.5950E-03

-1.5603E-03

-3.6625E-04

-3.6227E-05

1.9666E-06

-9.2682E-07

S2

2.4389E-02

-7.9166E-03

-1.2882E-03

-1.1052E-04

1.5824E-04

-2.8043E-05

-2.5048E-06

S3

1.2963E-01

-1.1386E-02

-5.3015E-04

-1.6703E-04

3.1415E-04

-7.3704E-05

6.6296E-06

S4

9.5810E-02

-4.1750E-03

-1.0668E-04

-1.4313E-04

1.6360E-04

-2.6141E-05

3.2348E-07

S5

-8.2727E-02

-7.2823E-03

-4.1404E-04

9.1669E-05

6.9076E-05

1.6935E-05

2.4793E-05

S6

-1.1224E-01

-1.4303E-04

-1.8740E-03

8.8381E-04

-1.4154E-04

2.6583E-05

1.1777E-05

S7

-3.6668E-01

4.6551E-02

-8.9070E-03

2.3120E-03

-4.5832E-04

1.8297E-05

-1.8435E-05

S8

-4.3775E-01

4.6417E-02

-9.7644E-03

2.2145E-03

-5.3012E-04

7.7962E-05

-1.2192E-05

Flour mark

A18

A20

A22

A24

A26

A28

A30

S1

-4.7267E-07

6.7527E-08

0.0000E+00

S2

1.0031E-06

3.7244E-08

0.0000E+00

S3

-1.7097E-06

7.8215E-07

0.0000E+00

S4

-1.5098E-06

2.2840E-07

-1.3292E-08

0.0000E+00

S5

2.1243E-05

1.0856E-05

0.0000E+00

S6

4.0016E-05

1.1498E-05

-3.8151E-06

-6.6869E-07

-6.8400E-09

8.6862E-08

0.0000E+00

S7

3.5004E-05

1.6125E-05

-3.4539E-06

0.0000E+00

S8

2.4272E-05

4.8101E-06

-3.4411E-06

0.0000E+00

TABLE 8

Fig. 11 shows an on-axis chromatic aberration curve of the optical imaging lens of example four, which represents the deviation of the convergence focus of light rays of different wavelengths after passing through the optical imaging lens. Fig. 12 shows a general diffraction modulation transfer function of the optical imaging lens of example four, which represents the diffraction performance of the optical imaging lens.

As can be seen from fig. 11 and 12, the optical imaging lens according to example four can achieve good imaging quality.

Example five

As shown in fig. 13 to 15, an optical imaging lens of example five of the present application is described. Fig. 13 shows a schematic diagram of an optical imaging lens structure of example five.

As shown in fig. 13, the optical imaging lens includes, in order from an object side to an image side: a stop STO, a first lens E1, a diffractive optical element DOE, a second lens E2, a third lens E3, a fourth lens E4, a filter E5, and an image plane S11.

The first lens element E1 has positive refractive power, and the object-side surface S1 of the first lens element is convex, and the image-side surface S2 of the first lens element is concave. The second lens element E2 has negative power, and the object-side surface S3 of the second lens element is convex and the image-side surface S4 of the second lens element is concave. The third lens element E3 has positive refractive power, and the object-side surface S5 of the third lens element is concave, and the image-side surface S6 of the third lens element is convex. The fourth lens element E4 has negative power, and the object-side surface S7 of the fourth lens element is convex and the image-side surface S8 of the fourth lens element is concave. Filter E5 has an object side S9 and an image side S10 of the filter. The light from the object sequentially passes through the respective surfaces S1 to S10 and is finally imaged on the imaging surface S11.

In this example, the total effective focal length f of the optical imaging lens is 14.40mm, the total length TTL of the optical imaging lens is 12.50mm, and the image height ImgH is 2.71 mm.

Table 9 shows a basic structural parameter table of the optical imaging lens of example five, in which the units of the radius of curvature, thickness/distance, focal length, and effective radius are all millimeters (mm).

TABLE 9

Table 10 shows the high-order term coefficients that can be used for each aspherical mirror surface in example five, wherein each aspherical mirror surface type can be defined by formula (1) given in example one above.

Flour mark

A4

A6

A8

A10

A12

A14

A16

S1

-3.4876E-02

-6.9922E-03

-2.1109E-03

-6.9462E-04

-1.6347E-04

-2.5658E-05

-5.4964E-06

S2

2.4227E-02

-5.8257E-03

-2.2213E-03

-3.1228E-04

1.0082E-04

1.2487E-05

-7.7705E-06

S3

1.3396E-01

-1.1102E-02

-7.3175E-04

-3.4679E-04

1.9562E-04

-4.0197E-07

-4.9206E-06

S4

1.0486E-01

-3.6370E-03

3.3450E-05

-1.8963E-04

8.6998E-05

9.5692E-06

-1.7291E-06

S5

-9.0035E-02

-7.7283E-03

-2.9015E-04

-9.5508E-05

4.5713E-05

-1.9012E-06

4.1328E-05

S6

-1.1750E-01

2.6413E-03

-2.7863E-03

8.2309E-04

-2.5340E-04

2.9387E-06

4.3048E-05

S7

-3.6183E-01

4.9269E-02

-1.0176E-02

2.4115E-03

-5.7213E-04

-1.3207E-05

2.7635E-05

S8

-4.3151E-01

4.5321E-02

-1.0111E-02

2.1893E-03

-5.3432E-04

7.7641E-05

2.9288E-05

Flour mark

A18

A20

A22

A24

A26

A28

A30

S1

-1.5980E-06

1.4256E-07

0.0000E+00

S2

1.7274E-07

4.4273E-07

0.0000E+00

S3

-7.8597E-07

1.1627E-07

0.0000E+00

S4

-1.4822E-06

-7.0466E-07

-1.6560E-07

0.0000E+00

S5

3.2437E-05

1.4504E-05

0.0000E+00

S6

5.8262E-05

9.2006E-06

-6.4339E-06

-8.9730E-07

9.7368E-08

-3.4598E-07

0.0000E+00

S7

6.0658E-05

9.8476E-06

-8.7503E-06

0.0000E+00

S8

3.3665E-05

-2.7248E-06

-6.7463E-06

0.0000E+00

Watch 10

Fig. 14 shows an on-axis chromatic aberration curve of the optical imaging lens of example five, which represents the deviation of the convergence focus of light rays of different wavelengths after passing through the optical imaging lens. Fig. 15 shows a general diffraction modulation transfer function of the optical imaging lens of example five, which represents the diffraction performance of the optical imaging lens.

As can be seen from fig. 14 and 15, the optical imaging lens according to example five can achieve good imaging quality.

In summary, the first to fifth examples respectively satisfy the relationships shown in table 11.

Conditions/examples	1	2	3	4	5
						f²/TTL(mm)	16.31	16.30	16.33	16.35	16.58
f1/R1	1.53	1.51	1.59	1.63	1.89
						f4/f2	1.14	1.18	1.21	1.19	1.24
f3/ImgH	5.09	5.33	5.29	5.26	5.32
						(R7+R8)/(R7-R8)	2.64	2.74	3.00	2.97	3.20
CT1/(CT2+CT3+CT4)	1.47	1.63	1.34	1.19	1.12
						BFL/T23	1.51	1.49	1.54	1.58	1.57
f34/f12	-2.30	-2.42	-2.43	-2.38	-2.64
						ET1/(ET3+ET4)	1.04	1.18	0.92	0.79	0.65
FOV(°)	21.12	21.08	21.08	21.08	21.08

Table 14 shows the effective focal lengths f of the optical imaging lenses of the first to fifth embodiments, and the effective focal lengths f1 to f4 of the respective lenses.

Example parameters	1	2	3	4	5
						f1(mm)	5.72	5.77	5.72	5.72	5.84
f2(mm)	-7.83	-7.85	-7.75	-7.78	-7.87
						f3(mm)	13.77	14.43	14.31	14.22	14.38
f4(mm)	-8.92	-9.24	-9.38	-9.28	-9.80
						f(mm)	14.41	14.40	14.40	14.40	14.40
TTL(mm)	12.73	12.73	12.70	12.69	12.50
						ImgH(mm)	2.71	2.71	2.71	2.71	2.71
FOV(°)	21.1	21.1	21.1	21.1	21.1

The present application also provides an imaging device whose electron photosensitive 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 digital camera, or may be an imaging module integrated on a mobile electronic device such as a mobile phone. The imaging device is equipped with the optical imaging lens described above.

It is to be understood that the above-described embodiments are only a few, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular is intended to include the plural unless the context clearly dictates otherwise, and it should be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of features, steps, operations, devices, components, and/or combinations thereof.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or described herein.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

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

a first lens having a positive focal power, an object side surface of the first lens being a convex surface;

a diffractive optical element having a diffraction efficiency greater than 80% for light having a wavelength in the range 470nm to 650 nm;

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

a third lens having a positive optical power;

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

the effective focal length f of the optical imaging lens and the axial distance TTL from the object side surface of the first lens to the imaging surface of the optical imaging lens meet the requirement of 15mm<f²/TTL<17mm。

2. The optical imaging lens of claim 1, wherein an effective focal length f1 of the first lens and a radius of curvature R1 of an object side of the first lens satisfy: 1.4< f1/R1< 2.0.

3. The optical imaging lens of claim 1, wherein an effective focal length f4 of the fourth lens and an effective focal length f2 of the second lens satisfy: 0.8< f4/f2< 1.5.

4. The optical imaging lens of claim 1, wherein the effective focal length f3 of the third lens and the ImgH of the half diagonal length of the effective pixel area on the imaging plane satisfy: 4.6< f3/ImgH < 5.6.

5. The optical imaging lens of claim 1, wherein a radius of curvature R7 of the object-side surface of the fourth lens and a radius of curvature R8 of the image-side surface of the fourth lens satisfy: 2.4< (R7+ R8)/(R7-R8) < 3.4.

6. The optical imaging lens of claim 1, wherein the central thickness CT1 of the first lens, the central thickness CT2 of the second lens, the central thickness CT3 of the third lens, and the central thickness CT4 of the fourth lens satisfy: 1.0< CT1/(CT2+ CT3+ CT4) < 1.8.

7. The optical imaging lens of claim 1, wherein an on-axis distance BFL from an image side surface of the fourth lens to the imaging surface, and an air interval T23 on the optical axis between the second lens and the third lens satisfy: 1.2< BFL/T23< 1.8.

8. The optical imaging lens of claim 1, wherein a combined focal length f34 of the third and fourth lenses and a combined focal length f12 of the first and second lenses satisfy: -2.8< f34/f12< -2.0.

9. The optical imaging lens according to claim 1, characterized in that the edge thickness ET1 of the first lens, the edge thickness ET3 of the third lens and the edge thickness ET4 of the fourth lens satisfy: 0.4< ET1/(ET3+ ET4) < 1.3.

10. An optical imaging lens, comprising, in order from an object side to an image side of the optical imaging lens along an optical axis of the optical imaging lens:

a third lens having a positive optical power;

the central thickness CT1 of the first lens, the central thickness CT2 of the second lens, the central thickness CT3 of the third lens and the central thickness CT4 of the fourth lens satisfy: 1.0< CT1/(CT2+ CT3+ CT4) < 1.8.