CN114217427A

CN114217427A - Optical lens

Info

Publication number: CN114217427A
Application number: CN202210165096.1A
Authority: CN
Inventors: 熊儒韬; 郑航鹏; 章彬炜; 曾昊杰; 张启灿
Original assignee: Jiangxi Lianyi Optics Co Ltd
Current assignee: Jiangxi Lianyi Optics Co Ltd
Priority date: 2022-02-23
Filing date: 2022-02-23
Publication date: 2022-03-22
Anticipated expiration: 2042-02-23
Also published as: CN114217427B

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 having a positive optical power, an object side surface of the first lens being concave at a paraxial region and having at least one inflection point, an image side surface of the first lens being convex at a paraxial region and having at least one inflection point; a diaphragm; a second lens having a negative optical power, the second lens having a convex object-side surface and a concave image-side surface at a paraxial region and having at least one inflection point; a third lens having a positive optical power, the third lens having a convex object-side surface and a convex image-side surface at a paraxial region. The optical lens has the advantages of accurate measurement and quick response.

Description

Optical lens

Technical Field

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

Background

At present, with the rapid development of science and technology, people also get great convenience in daily life. On AR augmented reality picture to and unmanned high accuracy high speed's information transfer, military and commercial unmanned aerial vehicle laser radar, infrared detection, all urgent needs more accurate, more efficient information transfer equipment to satisfy the requirement such as people to the performance outward appearance that equipment is more and more harsh.

Meanwhile, with the continuous updating and development of the technology of scientific and technological information transmission, the DToF (direct time of flight) technology well meets the requirements. The DToF optical lens can receive optical information carried by infrared light, transmit the optical information to a specific chip for photoelectric conversion, interpret the information transmitted in the infrared light, and realize photoelectric information conversion.

Disclosure of Invention

Therefore, the invention aims to provide an optical lens with accurate measurement and quick response.

The embodiment of the invention implements the above object by the following technical scheme.

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 positive optical power, an object side surface of the first lens being concave at a paraxial region and having at least one inflection point, an image side surface of the first lens being convex at a paraxial region and having at least one inflection point; a diaphragm; a second lens having a negative optical power, the second lens having a convex object-side surface and a concave image-side surface at a paraxial region and having at least one inflection point; a third lens having a positive optical power, the third lens having a convex object-side surface and a convex image-side surface at a paraxial region; wherein, the optical lens satisfies the following conditional expression: 0.3< (D11-D32)/f < 0.5; wherein D11 represents the optical aperture of the object side surface of the first lens, D32 represents the optical aperture of the image side surface of the third lens, and f represents the effective focal length of the optical lens.

Compared with the prior art, the optical lens provided by the invention has the advantages of accurate measurement and quick response by reasonably matching three lenses with specific focal power and shapes, and can be applied to the fields of AR, unmanned driving, laser radar and the like by realizing the photoelectric conversion effect by the chip at the rear end of the lens, thereby being greatly convenient for people to live.

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 graph showing F-Theta distortion of an optical lens according to a first embodiment of the present invention;

FIG. 4 is a graph of axial spherical aberration of an optical lens according to a first embodiment of the present invention;

FIG. 5 is a lateral chromatic aberration diagram of an optical lens according to a first embodiment of the present invention;

FIG. 6 is a schematic structural diagram of an optical lens system according to a second embodiment of the present invention;

FIG. 7 is a field curvature graph of an optical lens according to a second embodiment of the present invention;

FIG. 8 is a graph showing F-Theta distortion of an optical lens according to a second embodiment of the present invention;

FIG. 9 is a graph of on-axis spherical aberration of an optical lens according to a second embodiment of the present invention;

FIG. 10 is a lateral chromatic aberration diagram of an optical lens according to a second embodiment of the present invention;

FIG. 11 is a schematic structural diagram of an optical lens assembly according to a third embodiment of the present invention;

FIG. 12 is a field curvature graph of an optical lens according to a third embodiment of the present invention;

FIG. 13 is a graph showing F-Theta distortion of an optical lens according to a third embodiment of the present invention;

FIG. 14 is a graph of on-axis spherical aberration of an optical lens according to a third embodiment of the present invention;

FIG. 15 is a lateral chromatic aberration diagram of an optical lens according to a third embodiment of the present invention;

FIG. 16 is a schematic structural diagram of an optical lens assembly according to a fourth embodiment of the present invention;

FIG. 17 is a field curvature graph of an optical lens according to a fourth embodiment of the present invention;

FIG. 18 is a graph showing F-Theta distortion of an optical lens according to a fourth embodiment of the present invention;

FIG. 19 is a graph of on-axis spherical aberration of an optical lens according to a fourth embodiment of the present invention;

fig. 20 is a lateral chromatic aberration diagram of an optical lens according to a fourth embodiment of the present 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 present invention provides an optical lens, sequentially including, from an object side to an image plane along an optical axis: the lens comprises a first lens, a diaphragm, a second lens, a third lens and an optical filter.

Wherein the first lens element has a positive optical power, the object-side surface of the first lens element is concave at the paraxial region and has at least one inflection point, and the image-side surface of the first lens element is convex at the paraxial region and has at least one inflection point;

the second lens has negative focal power, the object side surface of the second lens is a convex surface, the image side surface of the second lens is a concave surface at a paraxial region and has at least one point of inflection;

the third lens element has a positive optical power, a convex object-side surface, and a convex image-side surface at a paraxial region.

As an embodiment, the optical lens satisfies the following conditional expression:

0.3<(D11-D32)/f<0.5；（1）

wherein D11 represents the optical aperture of the object side surface of the first lens, D32 represents the optical aperture of the image side surface of the third lens, and f represents the effective focal length of the optical lens.

When the condition formula (1) is satisfied, the corresponding chip is carried, more light rays can be received, more accurate information can be obtained, and more accurate information transmission can be realized. When the (D11-D32) <0.5, the light rays are transmitted to the chip through the third lens after entering the first lens, the concentration of the light rays is well modified, and the loss of information in the light rays is reduced; when the optical lens is 0.3< (D11-D32)/f, the optical lens can well ensure that the received light reaches the image height required by the chip, and the size of the chip is fully utilized, so that the information transmission efficiency is improved.

-23<（f-f2）/D <6；（2）

wherein f represents an effective focal length of the optical lens, f2 represents an effective focal length of the second lens, and D represents a diaphragm aperture of the optical lens.

For the conditional expression (2), when-23 < (f-f 2)/D, the large aperture characteristic of the lens can be well ensured, so that the lens can receive more light rays; when (f-f 2)/D is less than 6, the quantity of light rays can be reasonably controlled, aberration can be well modified, and the precision of information transmission is improved.

2.5<(D21+D22)/ f <3.5；（3）

wherein D21 represents the optical aperture of the object side surface of the second lens, D22 represents the optical aperture of the image side surface of the second lens, and f represents the effective focal length of the optical lens.

When the conditional expression (3) is satisfied, the aberration transmitted from the first lens to the second lens can be reasonably distributed, and the aberration can be transmitted to the third lens under the condition of smaller aberration. When the distance between the two lenses is 2.5< (D21+ D22)/f, more light rays can be transmitted from the first lens to the second lens, and the information transmission high-volume property is met; when (D21+ D22)/f < 3.5), the aberration from the first lens to the second lens can be well modified by the second lens while ensuring that the angle of the field of view is transmitted to the third lens, well modifying the aberration.

-2< f2/(D12+D31)<9；（4）

wherein f2 represents the effective focal length of the second lens, D12 represents the optical aperture of the image-side surface of the first lens, and D31 represents the optical aperture of the object-side surface of the third lens.

When satisfying conditional expression (4), the whole camera lens of control that can be reasonable has sufficient light flux, at the in-process that increases the light flux, makes the system have big light ring advantage to strengthen the imaging effect under the dark ring border when reducing the aberration of marginal field of view, make it also can obtain more light in the environment that light is not so sufficient, can receive more information on the messenger chip, thereby satisfy the demand that the user transmitted information in darker environment.

-5 mm²< TTL/(1/f1-1/f3)<-3 mm²；（5）

wherein TTL denotes an optical total length of the optical lens, f1 denotes an effective focal length of the first lens, and f3 denotes an effective focal length of the third lens.

When-5 mm is used for conditional formula (5)²<When TTL/(1/f1-1/f3), the total optical length of the lens can be reasonably controlled, so that the minimum total optical length is achieved under the condition of ensuring larger luminous flux; when TTL/(1/f1-1/f3)<-3 mm²In the process, the chromatic aberration after entering the lens is well modified by reasonably controlling the curvature of the lens.

0.2 mm^-1< CT2/(D21*f)<0.4 mm^-1；（6）

wherein CT2 represents the center thickness of the second lens, D21 represents the optical aperture of the object side of the second lens, and f represents the effective focal length of the optical lens.

For conditional formula (6), when 0.2mm^-1<When CT2/(D21 f), the aspheric eccentricity sensitivity of the second lens can be effectively controlled, so that the yield of actual production is improved; when CT2/(D21 f)<0.4 mm^-1In the process, the axial aberration of the lens can be effectively modified.

0 mm<YD-(DFOV*f/360)<0.2 mm；（7）

the DFOV represents a field angle corresponding to a diagonal line of an effective pixel area on an imaging surface of the optical lens, the YD represents an actual half-image height corresponding to the DFOV, and the f represents an effective focal length of the optical lens.

With respect to conditional expression (7), when 0mm < YD- (DFOV × f/360), distortion and field curvature can be well controlled to increase toward the positive direction; when YD- (DFOV f/360) <0.2 mm, the distortion and the field curvature can be well controlled to increase towards the negative direction, and the distortion and the field curvature are well modified.

0.3 mm^-1< FNO/(TTL-CT2)<0.4 mm^-1；（8）

wherein FNO denotes an actual working F-number of the optical lens, TTL denotes an optical total length of the optical lens, and CT2 denotes a center thickness of the second lens.

When the condition (8) is satisfied, the total optical length of the lens is ensured to be minimum while the luminous flux is improved by reasonably controlling the clear aperture of the lens, and ghost images reflected to the object side by the image side of the second lens can be effectively controlled.

-0.5<(R11+R32)(R11-R32)/(R21+R22)(R21-R22)<0；（9）

wherein R11 represents a radius of curvature of the first lens object-side surface, R32 represents a radius of curvature of the third lens image-side surface, R21 represents a radius of curvature of the second lens object-side surface, and R22 represents a radius of curvature of the second lens image-side surface.

When the condition formula (9) is satisfied, three lenses are reasonably matched, so that the special radius between the three lenses can fully play the role of light refraction, and the resolving power of the lens is effectively improved.

2<(D21+D22)/(f21+f22)<12；（10）

wherein D21 represents the optical aperture of the object-side surface of the second lens, D22 represents the optical aperture of the image-side surface of the second lens, f21 represents the effective focal length of the object-side surface of the second lens, and f22 represents the effective focal length of the image-side surface of the second lens.

For the conditional expression (10), when 2< (D21+ D22)/(f21+ f22), the aperture of the lens group can be well controlled, which is beneficial to structural design; when the (D21+ D22)/(f21+ f22) <12, the discrete size of the defocus curve of each field can be well controlled, and meanwhile, the imaging quality of the lens is modified.

In one embodiment, the first lens, the second lens and the third lens are aspheric lenses. The aspheric lens can effectively reduce the number of the lenses, correct aberration and provide better optical performance.

The invention is further illustrated below in the following examples. In various embodiments, the thickness, the curvature radius, and the material selection of each lens in the optical lens are different, and the specific differences can be referred to in 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 each embodiment of the present invention, when the lenses in the optical lens are aspherical lenses, each aspherical surface type satisfies the following equation:

wherein z is the distance rise from the aspheric surface vertex when the aspheric surface is at the position of height h along the optical axis direction, c is the paraxial curvature of the surface, k is conic coefficient, A_2iIs the aspheric surface type coefficient of 2i order.

First embodiment

Referring to fig. 1, a schematic structural diagram of an optical lens 100 according to a first embodiment of the present invention is shown, where the optical lens 100 sequentially includes, from an object side to an image plane S9 along an optical axis direction: a first lens L1, a stop ST, a second lens L2, a third lens L3, and a filter G1.

The first lens L1 is a plastic aspheric lens with positive optical power, the object-side surface S1 of the first lens has at least one inflection point being concave at the paraxial region, and the image-side surface S2 of the first lens has at least one inflection point being convex at the paraxial region;

the second lens element L2 is a plastic aspheric lens with negative power, 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 at the paraxial region and has at least one inflection point;

the third lens element L3 is a plastic aspheric lens with positive power, the object-side surface S5 of the third lens element is convex, and the image-side surface S6 of the third lens element is convex at the paraxial region.

Filter G1 has an object side S7 and an image side S8.

Specifically, the design parameters of the optical lens 100 provided in the present embodiment are shown in table 1, where R represents a radius of curvature (unit: mm), d represents an optical surface distance (unit: mm), and n represents_dD-line refractive index, V, of the material_dRepresents the abbe number of the material.

TABLE 1

The surface shape coefficients of the 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, F-Theta distortion, chromatic aberration of point-on-axis spherical aberration, and lateral chromatic aberration of the optical lens 100 are shown in fig. 2, 3, 4, and 5, respectively. As can be seen from fig. 2 to 5, the field curvature is controlled within ± 0.2mm, the distortion is controlled within 12%, the on-axis spherical aberration is controlled within ± 0.03mm, and the lateral aberration is controlled within ± 1 μm, which indicates that the field curvature, distortion and chromatic aberration of the optical lens 100 are well corrected.

Second embodiment

Referring to fig. 6, the structure of the optical lens 200 of the present embodiment is not greatly changed from that of the optical lens 100 of the first embodiment, wherein the largest change is the thickness of the second lens element.

The present embodiment provides the relevant parameters of each lens in the optical lens 200 as shown in table 3.

TABLE 3

The surface shape coefficients of the 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, F-Theta distortion, chromatic aberration of point-on-axis spherical aberration, and lateral chromatic aberration of the optical lens 200 are shown in fig. 7, 8, 9, and 10, respectively. It can be seen from fig. 7 to 10 that the field curvature is controlled within ± 0.2mm, the distortion is controlled within 15%, the on-axis spherical aberration is controlled within ± 0.03mm, and the lateral aberration is controlled within ± 1 μm, which indicates that the field curvature, distortion and chromatic aberration of the optical lens 200 are well corrected.

Third embodiment

Referring to fig. 11, a schematic structural diagram of an optical lens 300 provided in the present embodiment is shown, where a 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, and a largest difference is that an inclination angle of an object-side edge surface of the first lens element is smaller.

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, F-Theta distortion, on-axis spherical aberration, and lateral chromatic aberration of the optical lens 300 are shown in fig. 12, 13, 14, and 15, respectively. As can be seen from fig. 12 to 15, the curvature of field is controlled within ± 0.2mm, the distortion is controlled within 15%, the on-axis spherical aberration is controlled within ± 0.02mm, and the lateral aberration is controlled within ± 1.5 μm, which indicates that the curvature of field, the distortion and the chromatic aberration of the optical lens 300 are well corrected.

Fourth embodiment

Referring to fig. 16, a schematic structural diagram of an optical lens 400 provided in this embodiment is shown, and the optical lens 400 in this embodiment has a structure substantially the same as that of the optical lens 100 in the first embodiment except for a surface type coefficient.

The relevant parameters of each lens in the optical lens 400 in the present embodiment are shown in table 7.

TABLE 7

The surface shape coefficients of the aspherical surfaces of the optical lens 400 in the present embodiment are shown in table 8.

TABLE 8

In the present embodiment, graphs of curvature of field, F-Theta distortion, chromatic aberration of point-on-axis spherical aberration, and lateral chromatic aberration of the optical lens 400 are shown in fig. 17, 18, 19, and 20, respectively. It can be seen from fig. 17 to 20 that the curvature of field is controlled within ± 0.2mm, the distortion is controlled within ± 15%, the on-axis spherical aberration is controlled within ± 0.03mm, and the lateral aberration is controlled within ± 1.5 μm, which indicates that the curvature of field, distortion and chromatic aberration of the optical lens 400 are well corrected.

Table 9 shows the optical characteristics corresponding to the above four embodiments, which mainly include the effective focal length f, the total optical length TTL, and the numerical values corresponding to each conditional expression.

TABLE 9

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

(1) through the specific collocation of the first lens and the third lens and the reasonable arrangement of the shapes of the lenses, the optical lens has the characteristic of ultra-large aperture light transmission, and can better meet the development trend of the current DToF lens.

(2) The second lens with a specific surface type and the three plastic aspheric lenses with specific focal power are adopted, so that ghost images generated when light is received can be greatly reduced, and the precision of lens information transmission is improved.

(3) Compared with the infrared detection lens with high price, the invention has mature manufacturing process on the premise of ensuring high luminous flux, greatly reduces the manufacturing cost and is more beneficial to market popularization.

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 examples are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present 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 positive optical power, an object side surface of the first lens being concave at a paraxial region and having at least one inflection point, an image side surface of the first lens being convex at a paraxial region and having at least one inflection point;

a diaphragm;

a second lens having a negative optical power, the second lens having a convex object-side surface and a concave image-side surface at a paraxial region and having at least one inflection point;

a third lens having a positive optical power, the third lens having a convex object-side surface and a convex image-side surface at a paraxial region;

wherein, the optical lens satisfies the following conditional expression:

0.3<(D11-D32)/f<0.5；

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

-23<（f-f2）/D <6；

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

2.5<(D21+D22)/ f <3.5；

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

-2< f2/(D12+D31)<9；

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

-5 mm²< TTL/(1/f1-1/f3)<-3 mm²；

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

0.2 mm^-1< CT2/(D21*f)<0.4 mm^-1；

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

0 mm<YD-(DFOV*f/360)<0.2 mm；

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

0.3 mm^-1< FNO/(TTL-CT2)<0.4 mm^-1；

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

-0.5<(R11+R32)(R11-R32)/(R21+R22)(R21-R22)<0；

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

2<(D21+D22)/(f21+f22)<12；