CN112987248B

CN112987248B - Optical imaging system, image capturing module and electronic device

Info

Publication number: CN112987248B
Application number: CN202110178249.1A
Authority: CN
Inventors: 黄怀毅; 李宗政
Original assignee: Jiangxi OMS Microelectronics Co Ltd
Current assignee: Jiangxi OMS Microelectronics Co Ltd
Priority date: 2021-02-09
Filing date: 2021-02-09
Publication date: 2022-06-28
Anticipated expiration: 2041-02-09
Also published as: CN112987248A

Abstract

The application provides an optical imaging system, gets for instance module and electron device, optical imaging system includes by the thing side to the image side in proper order: an aperture; a first lens having a positive refracting power; a second lens having a positive refracting power; a third lens having a positive refracting power; a fourth lens having a negative refracting power; wherein the optical imaging system satisfies the following conditional expression: -1.5< R5/EFL < -0.3; where R5 is the radius of curvature of the object-side surface of the third lens at the optical axis and EFL is the effective focal length of the optical imaging system. The optical imaging system is arranged by mixing the lenses with positive and negative bending forces, and the lens matching of the positive and negative bending forces can mutually counteract the aberration generated by each other, so that the optical distortion of the optical imaging system is smaller, and the optical imaging system is ensured to have higher imaging quality; and the space between the effective focal length of the optical imaging system and the lens can be effectively controlled, so that the purpose of short total length is achieved, and the requirement of lightness and thinness of the optical imaging system is met.

Description

Optical imaging system, image capturing module and electronic device

Technical Field

The present disclosure relates to optical imaging technologies, and particularly to an optical imaging system, an image capturing module and an electronic device.

Background

In recent years, 3D infrared sensing lenses are widely used in mobile phones, especially front lenses, and in 3D applications, mobile phones are thinner and thinner to place the front lenses.

In the process of implementing the invention, the inventor finds that at least the following problems exist in the prior art: along with the improvement of the performance of photosensitive elements such as a Charge Coupled Device (CCD) or a Complementary Metal Oxide Semiconductor (CMOS) and the like, the number of pixels of the photosensitive elements is increased and the size of the pixels is reduced, so that the size of the image capturing module is increased; in order to ensure the imaging quality, the size of the conventional optical imaging system is large, for example, the optical lens has a large head aperture and a long overall length, which makes the size of the 3D infrared sensing lens become large as a whole, and is not favorable for the current trend of miniaturization and light weight of the 3D infrared sensing lens.

Disclosure of Invention

In view of the above, it is desirable to provide an optical imaging system, an image capturing module and an electronic device to solve the above problems.

An embodiment of the present application provides an optical imaging system, sequentially from an object side to an image side, comprising:

an aperture;

a first lens having a positive refracting power;

a second lens having a positive refracting power;

a third lens having a positive refracting power;

A fourth lens having a negative refracting power;

wherein the optical imaging system satisfies the following conditional expression:

-1.5<R5/EFL<-0.3；

wherein R5 is a radius of curvature of an object side surface of the third lens at an optical axis, and EFL is an effective focal length of the optical imaging system.

The optical imaging system is arranged by mixing the lenses with positive and negative bending forces, and the lens matching of the positive and negative bending forces can mutually counteract the aberration generated by each other, so that the optical distortion of the optical imaging system is smaller, and the optical imaging system is ensured to have higher imaging quality; furthermore, the third lens surface type can be reasonably controlled, so that the third lens surface type cannot be excessively bent, the processing difficulty of the lens is reduced, the problems of lens breakage and the like which easily occur in the surface type process forming process are avoided, in addition, the third lens surface type is not too straight, the insufficient bending force strength of the lens is avoided, and the phenomena of insufficient aberration correction and the like are avoided. Therefore, by satisfying the above formula, the distribution of the bending force between the third lens and the optical imaging system is facilitated, and the aberrations such as field curvature, distortion and the like of the marginal field can be corrected; meanwhile, due to the reasonable configuration of the surface shape and the bending force, the optical imaging system can effectively control the effective focal length of the optical imaging system and the space between the lenses on the premise of meeting the appropriate field angle, so that the purpose of short total length is achieved, and the requirement of light and thin of the optical imaging system is met.

In some embodiments, the optical imaging system satisfies the following conditional expression:

-0.2mm<SAG21<0mm；

SAG21 is the distance from the intersection point of the second lens object side surface and the optical axis to the maximum effective radius of the second lens object side surface in the direction parallel to the optical axis.

Therefore, the air space at the effective radius of the first lens and the second lens is small, the lenses do not need to be assembled by thick elements such as gaskets or gaskets, the assembling by the gaskets or the gaskets needs to be carried out die sinking or metal part assistance, the cost is high, and the lenses can be assembled by slices such as Soma and the like by meeting the relational expression, so the assembling cost is low.

-0.4<SAG21/CT2<0；

and SAG21 is the distance from the intersection point of the object side surface and the optical axis of the second lens to the maximum effective radius of the object side surface of the second lens in the direction parallel to the optical axis, and CT2 is the thickness of the second lens on the optical axis.

Therefore, the effective caliber of the second lens is reduced, and the processing and the forming of the lens are facilitated; in addition, the thickness of the second lens can be effectively controlled, so that the occupied space of the lens can be shortened, and the optical imaging system has the characteristics of short total length and small size on the basis of not influencing the imaging quality.

TTL/EFL<1.6；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an imaging surface of the optical imaging system, and EFL is an effective focal length of the optical imaging system.

Therefore, the optical imaging system can be effectively controlled to achieve the purpose of short total length under the condition of meeting the appropriate effective focal length, and the requirement of lightness and thinness of the optical imaging system is met.

-2.0<SAG31/CT3<-0.2；

wherein SAG31 is a distance in a direction parallel to the optical axis from an intersection point of the object-side surface of the third lens and the optical axis to a maximum effective radius of the object-side surface of the third lens, and CT3 is a thickness of the third lens on the optical axis.

Therefore, the effective caliber of the third lens is reduced, and the processing and the molding of the lens are facilitated; the thickness of the third lens can be effectively controlled, so that the occupied space of the lens can be shortened, and the optical imaging system has the characteristics of short total length and small size on the basis of not influencing the imaging quality.

FNO<1.4；

Wherein FNO is an f-number of the optical imaging system.

So, can make optical imaging system have great light ring, increase the light inlet quantity, help promoting the formation of image quality, make optical imaging system have the characteristics of big depth of field, be favorable to drawing near remote object, be favorable to the detail characteristic of outstanding quilt shooting subject, realize high-quality formation of image.

Vd<30；

and Vd is the d-ray Abbe number of any one of the second lens, the third lens and the fourth lens.

Therefore, the d-ray abbe numbers of the second lens to the fourth lens are proper, so that the refractive indexes of the materials are matched with each other, chromatic aberration and chromatic dispersion generated among the lenses are favorably balanced, the imaging quality of the optical imaging system is improved, the conditional expressions are met, the lenses are simple to manufacture, and the manufacturing cost of the optical imaging system is favorably reduced.

0.45<f2/f1<2.6；

wherein f1 is the effective focal length of the first lens, and f2 is the effective focal length of the second lens.

Therefore, the first lens has positive bending force, which is beneficial to converging light rays on the object side to enable the optical imaging system to have a larger visual angle, and the second lens has positive bending force which is beneficial to further collecting and refracting the light rays by the light ray imaging system to enable the light rays reaching the imaging surface of the optical imaging system to be enough, so that the imaging resolving power of the optical imaging lens is improved; meanwhile, the positive bending force lens is configured through reasonable bending force, so that the total length of the optical imaging system can be compressed, and the light and thin requirements can be met.

1.5<d23/d12<3.4；

wherein d23 is an air space on the optical axis between the image-side surface of the second lens and the object-side surface of the third lens, and d12 is an air space on the optical axis between the image-side surface of the first lens and the object-side surface of the second lens.

Therefore, the first lens, the second lens and the third lens can obtain reasonable space layout by utilizing proper air space configuration among the lenses, so that the reasonable distribution of the bending force of the optical imaging system is facilitated, the dispersion of the focal power of the system is facilitated, the molding processing of each lens is facilitated, the surface type of each lens of the optical imaging system can be reasonably adjusted, and the manufacturing sensitivity of each lens is reduced.

In some embodiments, the object-side surface and the image-side surface of the second lens each have at least one inflection point, and the object-side surface and the image-side surface of the fourth lens each have at least one inflection point.

Therefore, the second lens and the fourth lens are controlled to be in a face shape, so that the lenses are tightly arranged, the total length of the optical lens is short, and the existing requirements for miniaturization and light weight and thinness are met.

An embodiment of the present application provides an image capturing module, including:

A photosensitive element; and

in the above optical imaging system, the optical imaging system is disposed on the object side of the photosensitive element.

The optical imaging system in the image capturing module is arranged by mixing the lenses with positive and negative bending forces, and the lens matching of the positive and negative bending forces can mutually counteract the aberration generated by each other, so that the optical distortion of the optical imaging system is smaller, and the optical imaging system is ensured to have higher imaging quality; and the third lens surface type can be reasonably controlled, so that the third lens surface type cannot be excessively bent, the processing difficulty of the lens is reduced, the problems of lens breakage and the like which are easy to occur in the surface type process forming process are avoided, in addition, the third lens surface type is not too flat, the insufficient bending force strength of the lens is avoided, and the phenomena of insufficient aberration correction and the like are avoided. Therefore, by satisfying the above formula, the distribution of the bending force between the third lens and the optical imaging system is facilitated, and the aberrations such as field curvature, distortion and the like of the marginal field of view can be corrected; meanwhile, due to the reasonable configuration of the surface shape and the bending force, the optical imaging system can effectively control the effective focal length of the optical imaging system and the space between the lenses on the premise of meeting the appropriate field angle, so that the purpose of short total length is achieved, and the requirement of light and thin of the optical imaging system is met.

An embodiment of the present application provides an electronic device, including:

a body; and

as mentioned above, the image capturing module is arranged on the body.

The electronic device comprises an image capturing module, wherein the optical imaging system in the image capturing module is arranged by mixing lenses with positive and negative bending forces, and the lens matching of the positive and negative bending forces can mutually offset the aberration generated by each other, so that the optical distortion of the optical imaging system is smaller, and the higher imaging quality of the optical imaging system is ensured; and the third lens surface type can be reasonably controlled, so that the third lens surface type cannot be excessively bent, the processing difficulty of the lens is reduced, the problems of lens breakage and the like which are easy to occur in the surface type process forming process are avoided, in addition, the third lens surface type is not too flat, the insufficient bending force strength of the lens is avoided, and the phenomena of insufficient aberration correction and the like are avoided. Therefore, by satisfying the above formula, the distribution of the bending force between the third lens and the optical imaging system is facilitated, and the aberrations such as field curvature, distortion and the like of the marginal field can be corrected; meanwhile, due to the reasonable configuration of the surface shape and the bending force, the optical imaging system can effectively control the effective focal length of the optical imaging system and the space between the lenses on the premise of meeting the appropriate field angle, so that the purpose of short total length is achieved, and the requirement of light and thin of the optical imaging system is met.

Drawings

Fig. 1 is a schematic structural view of an optical imaging system according to a first embodiment of the present application.

Fig. 2 is a schematic view of spherical aberration, astigmatism and distortion of the optical imaging system according to the first embodiment of the present application.

Fig. 3 is a schematic structural diagram of an optical imaging system according to a second embodiment of the present application.

Fig. 4 is a schematic view of spherical aberration, astigmatism and distortion of an optical imaging system according to a second embodiment of the present application.

Fig. 5 is a schematic structural diagram of an optical imaging system according to a third embodiment of the present application.

Fig. 6 is a schematic view of spherical aberration, astigmatism and distortion of an optical imaging system according to a third embodiment of the present application.

Fig. 7 is a schematic structural diagram of an optical imaging system according to a fourth embodiment of the present application.

Fig. 8 is a schematic view of spherical aberration, astigmatism and distortion of an optical imaging system according to a fourth embodiment of the present application.

Fig. 9 is a schematic structural diagram of an optical imaging system according to a fifth embodiment of the present application.

Fig. 10 is a schematic view of spherical aberration, astigmatism and distortion of an optical imaging system according to a fifth embodiment of the present application.

Fig. 11 is a schematic structural diagram of an image capturing module according to an embodiment of the present application.

Fig. 12 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

Description of the main elements

Optical imaging system 10

First lens L1

Second lens L2

Third lens L3

Fourth lens L4

Optical filter L5

Object side surfaces S2, S4, S6 and S8

Image sides S3, S5, S7, S9

Imaging plane IMG

Photosensitive element 20

Image capturing module 100

Housing 200

Body 400

Electronic device 500

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. 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 application.

In the description of the present application, it is to be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the application and for simplicity in description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and thus should not be considered limiting. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

In the description of the present application, it should be noted that, unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, a fixed connection, a detachable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as the case may be.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact of the first and second features, or may comprise contact of the first and second features not directly but through another feature in between. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the application. To simplify the disclosure of the present application, specific example components and arrangements are described below. Of course, they are merely examples and are not intended to limit the present application. Moreover, the present application may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, examples of various specific processes and materials are provided herein, but one of ordinary skill in the art may recognize applications of other processes and/or use of other materials.

Referring to fig. 1, an optical imaging system 10 according to an embodiment of the present disclosure includes, in order from an object side to an image side: the stop STO, the first lens L1 having a positive bending force, the second lens L2 having a positive bending force, the third lens L3 having a positive bending force, and the fourth lens L4 having a negative bending force.

Specifically, the first lens L1 has an object-side surface S2 and an image-side surface S3, the second lens L2 has an object-side surface S4 and an image-side surface S5, the third lens L3 has an object-side surface S6 and an image-side surface S7, and the fourth lens L4 has an object-side surface S8 and an image-side surface S9. Wherein the object side surface S4 and the image side surface S5 of the second lens L2 are curved toward the image side at a principal ray of the central field of view, and are curved toward the object side at a region outside the central field of view; the object side surface S8 and the image side surface S9 of the fourth lens L4 are curved toward the image side at the principal ray of the central field of view, and are curved toward the object side at the region other than the principal ray of the peripheral field of view.

The optical imaging system 10 is formed by mixing and arranging the lenses with positive and negative bending forces, and the lens matching of the positive and negative bending forces can mutually offset the aberration generated by each other, so that the optical distortion of the optical imaging system is smaller, and the optical imaging system 10 is ensured to have higher imaging quality.

In some embodiments, the optical imaging system 10 satisfies the following conditional expression:

TTL/EFL<1.6；

wherein, TTL is an axial distance from the object side surface S2 of the first lens element L1 to the imaging plane IMG of the optical imaging system 10, and EFL is an effective focal length of the optical imaging system 10.

The optical imaging system 10 can be effectively controlled to achieve the purpose of short total length under the condition of meeting the appropriate effective focal length, and the requirements of light and thin of the optical imaging system are met. When the above formula is exceeded, the rise of the object-side surface of the first lens is larger than the effective focal length of the optical imaging system 10, and the thickness of the first lens is larger, which is not favorable for realizing the short total length effect of the optical imaging system 10.

-0.2mm<SAG21<0mm；

the SAG21 is a distance in a direction parallel to the optical axis from an intersection point of the object-side surface S4 of the second lens L2 and the optical axis to the maximum effective radius of the object-side surface S4 of the second lens L2, and the direction from the object side to the image side is negative.

Thus, the air gap between the effective radii of the first lens L1 and the second lens L2 is small, so that the lenses do not need to be assembled by thick elements such as gaskets or spacers, and the assembling by the gaskets or spacers requires die sinking or metal part assistance, which results in high cost. When the range is out of the above range, it is necessary to assemble the parts with special work such as a spacer, and the spacer is required to be opened and molded (or made of metal), which is costly.

-0.4<SAG21/CT2<0；

SAG21 is the distance from the intersection point of the object side surface S4 of the second lens L2 and the optical axis to the maximum effective radius of the object side surface S4 of the second lens L2 in the direction parallel to the optical axis, and CT2 is the thickness of the second lens L2 in the optical axis.

Thus, the effective caliber of the second lens L2 is reduced, and the processing and molding of the lens are facilitated; in addition, the thickness of the second lens L2 can be effectively controlled, which is beneficial to shortening the occupied space of the lens, so that the optical imaging system has the characteristics of short total length and small size on the basis of not affecting the imaging quality. When the range is exceeded, the rise of the object-side surface of the second lens is large relative to the focal length of the optical imaging system 10, and the thickness of the second lens is large, which is disadvantageous in achieving the short overall length effect of the optical imaging system 10.

In some embodiments, the optical imaging system 10 satisfies the following conditional expressions:

-1.5<R5/EFL<-0.3；

where R5 is a radius of curvature of the object-side surface S6 of the third lens L3 at the optical axis, and EFL is a focal length of the optical imaging system 10.

So, third lens L3 face type can obtain reasonable control, makes third lens L3 face type can not excessively bend, has reduced the processing degree of difficulty of lens to avoid the lens that easily appears to break scheduling problem in the face type technology forming process, in addition, third lens L3 face type also can not too straight, has avoided lens bending strength not enough, thereby has avoided phenomenons such as aberration correction not enough. Therefore, by satisfying the above formula, it is beneficial to the distribution of the bending force between the third lens L3 and the optical imaging system 10, and the aberrations such as curvature of field and distortion of the fringe field can be corrected; meanwhile, due to the reasonable configuration of the surface shape and the bending force, the optical imaging system 10 can effectively control the effective focal length of the optical imaging system 10 and the space between the lenses on the premise of meeting the appropriate field angle, so that the purpose of short total length is achieved, and the requirement of light weight and thinness of the optical imaging system 10 is met.

-2.0<SAG31/CT3<-0.2；

The SAG31 is a distance in a direction parallel to the optical axis from an intersection point of the object-side surface S6 of the third lens L3 and the optical axis to the maximum effective radius of the object-side surface S6 of the third lens L3, and the CT3 is a thickness of the third lens L3 on the optical axis.

Thus, the effective caliber of the third lens L3 is reduced, and the processing and molding of the lens are facilitated; the effective radius range and thickness of the third lens L3 can also be effectively controlled, which is beneficial to shortening the lens occupation space, so that the optical imaging system 10 has the characteristics of short overall length and small size on the basis of not affecting the imaging quality. When exceeding the above range, the rise of the object-side surface of the third lens is large relative to the effective focal length of the optical imaging system 10, and the thickness of the third lens L3 is large, which is disadvantageous in achieving the short overall length effect of the optical imaging system 10.

FNO<1.4；

wherein FNO is the f-number of the optical imaging system 10.

So, can make optical imaging system 10 have great light ring, increase the light inlet quantity, help promoting the formation of image quality, make optical imaging system 10 have the characteristics of big depth of field, be favorable to drawing near remote object, be favorable to the detail characteristic of outstanding quilt shooting main part, realize high-quality formation of image.

Vd<30；

Thus, the d-ray abbe numbers of the second lens L2 to the fourth lens L4 are appropriate, so that the refractive indexes of the materials are matched with each other, which is beneficial to balancing chromatic aberration and chromatic dispersion generated among the lenses, thereby improving the imaging quality of the optical imaging system 10 and satisfying the above conditional expressions, the lenses are simple to manufacture, and the manufacturing cost of the optical imaging system 10 is beneficial to being reduced. When the optical characteristics are out of the above range, the materials of the second lens L2 to the fourth lens L4 are difficult to manufacture and have high cost.

0.45<f2/f1<2.6；

wherein f1 is the effective focal length of the first lens L1, and f2 is the effective focal length of the second lens L2.

Thus, the first lens L1 has positive refractive power, which is beneficial to converging light rays on the object side, so that the optical imaging system 10 has a larger viewing angle, and the second lens L2 has positive refractive power, which is beneficial to the optical imaging system 10 to further collect and refract light rays, so that the light rays reaching the imaging surface of the optical imaging system 10 are sufficient, and the imaging resolution of the optical imaging system 10 is improved; meanwhile, the positive bending force lens is configured through reasonable bending force, so that the total length of the optical imaging system can be compressed, and the light and thin requirements can be met.

1.5<d23/d12<3.4；

wherein d23 is an air space on the optical axis between the image-side surface S5 of the second lens L2 and the object-side surface S6 of the third lens L3, and d12 is an air space on the optical axis between the image-side surface S3 of the first lens L1 and the object-side surface S5 of the second lens L2.

Thus, the proper arrangement of the air spaces among the lenses is helpful for obtaining a reasonable spatial layout of the first lens L1, the second lens L2 and the third lens L3, thereby being helpful for reasonable distribution of the bending force of the optical imaging system 10, being beneficial for dispersion of the system focal power, being beneficial for molding processing of each lens, being further beneficial for reasonable adjustment of the surface type of each lens of the optical imaging system 10, and reducing the manufacturing sensitivity of each lens. Beyond that, it is not conducive to the distribution of the bending force of the system, nor to the rational adjustment of the profile and manufacturing sensitivity of the optical imaging system 10.

In some embodiments, the object-side surface S4 and the image-side surface S5 of the second lens L2 each have at least one inflection point, and the object-side surface S8 and the image-side surface S9 of the fourth lens L4 each have at least one inflection point.

In this way, by controlling the surface shapes of the second lens L2 and the fourth lens L4, the lenses are closely arranged, so that the total length of the optical lens is short, and the requirements of miniaturization and lightness and thinness in the prior art are met.

In some embodiments, further comprising:

the filter L5 is disposed on the image side of the fourth lens element L4.

In this way, light rays in other wavelength bands, such as visible light, can be filtered out, and only light rays in a desired wavelength band can pass through, so as to ensure the imaging quality of the optical imaging system 10 in the light rays in the desired wavelength band; the light beams in the infrared band and other bands may also be filtered, and only the visible light may pass through, which is not limited herein, as the case requires.

When the optical imaging system 10 is used for imaging, light rays emitted or reflected by a subject enter the optical imaging system 10 from the object side direction, sequentially pass through the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the optical filter L5, and finally converge on the imaging plane IMG.

In some embodiments, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the filter L5 are all made of plastic, and in this case, the plastic lens can reduce the weight of the optical imaging system 10 and reduce the production cost. In some embodiments, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the filter L5 are made of glass, and in this case, the optical imaging system 10 can endure higher temperature and has better optical performance. In other embodiments, only the first lens L1 may be made of glass, and the other lenses are made of plastic, in which case, the first lens L1 closest to the object side can better withstand the influence of the ambient temperature on the object side, and the production cost of the optical imaging system 10 is kept low because the other lenses are made of plastic. In other embodiments, the material of the first lens element L1 is glass, and the materials of the other lens elements can be combined arbitrarily.

First embodiment

Referring to fig. 1, the optical imaging system 10 of the first embodiment includes, in order from an object side to an image side: the stop STO, the first lens L1 having a positive bending force, the second lens L2 having a positive bending force, the third lens L3 having a positive bending force, the fourth lens L4 having a negative bending force, and the filter L5.

The object-side surface S2 of the first lens element L1 is convex at the paraxial region, and the image-side surface S3 is concave at the paraxial region.

The object-side surface S4 of the second lens element L2 is convex at the paraxial region, and the image-side surface S5 is concave at the paraxial region.

The object-side surface S6 of the third lens element L3 is concave at the paraxial region, and the image-side surface S7 is convex at the paraxial region.

The object-side surface S8 of the fourth lens element L4 is convex at the paraxial region, and the image-side surface S9 is concave at the paraxial region.

The reference wavelength of the optical imaging system in the first embodiment is 940nm, and the optical imaging system 10 in the first embodiment has the following specific parameters, and the units of the Y radius, the thickness, and the half aperture are all millimeters (mm).

TABLE 1

It should be noted that EFL is the effective focal length of the optical imaging system 10, TTL is the total length of the optical imaging system 10, and FNO is the f-number of the optical imaging system 10.

TABLE 2

Number of noodles

S2

S3

S4

S5

S6

S7

S8

S9

R

1.7474E+00

2.6689E+00

3.1697E+00

4.7895E+00

-2.3556E+00

-9.3392E-01

1.8637E+00

7.9730E-01

K

-1.2514E+01

3.2181E+00

-6.0785E+00

-6.6765E+00

-1.0216E+00

-3.2160E+00

-2.5994E+01

-7.3615E+00

A4

2.5245E-01

-4.5349E-02

-4.8484E-02

-1.8047E-02

4.0022E-02

1.6940E-02

-1.0239E-01

-1.0709E-01

A6

-2.9225E-01

-1.0492E-02

-2.7616E-02

-5.7405E-02

-6.6289E-02

-1.6304E-01

2.5913E-02

4.4207E-02

A8

3.0042E-01

-2.1540E-02

-7.2253E-02

-1.1110E-02

-7.7315E-02

1.6449E-01

1.3713E-02

-1.1945E-02

A10

-2.1096E-01

2.2532E-02

7.5968E-02

-2.8850E-03

9.1752E-02

-9.9656E-02

-8.5542E-03

1.7493E-03

A12

9.2043E-02

-2.3495E-02

-6.4908E-02

1.6382E-03

-2.8630E-03

3.0033E-02

3.1017E-04

-3.3625E-04

A14

-2.1554E-02

6.5279E-03

2.4236E-02

6.5569E-04

-6.2268E-02

3.1857E-04

4.7325E-04

6.7626E-05

A16

1.8336E-03

0.0000E+00

6.3409E-04

6.3977E-04

2.7273E-02

-4.6501E-04

-6.5950E-05

-6.6413E-06

In the first lens L1 to the fourth lens L4, both the object-side surface and the image-side surface of each lens are aspheric. The shape of the aspheric surface can be determined by the following formula:

Wherein, Z is a distance rise from a vertex of the aspheric surface when the aspheric surface is at a position with a height h along the optical axis direction, and it should be noted that the vertex here is an intersection point of the aspheric surface and the optical axis; c is the paraxial curvature of the aspheric surface, and c is 1/R (i.e. paraxial curvature c is the reciprocal of curvature radius R in table 1); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 2 shows the coefficients R, K, A4, A6, A8, A10, A12, A14 and A16 of the high-order terms from S2 to S9 in example I.

Fig. 2 shows a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the optical imaging system 10 of the first embodiment, wherein the longitudinal spherical aberration curves represent convergent focus deviations of less than 0.03mm after light rays with wavelengths of 920nm, 940nm and 960nm pass through the lenses of the optical imaging system 10 respectively; the astigmatism reference wavelengths are 920nm, 940nm and 960nm, and the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature, wherein the maximum values of the arc loss field curvature (corresponding to X in the figure) and the meridional field curvature (corresponding to Y in the figure) are less than 0.05 mm; the reference wavelength of distortion is 940nm, and the distortion curve represents the distortion magnitude values corresponding to different field angles, wherein the maximum distortion is less than 15%. As can be seen from fig. 2, the optical imaging system 10 according to the first embodiment can achieve good imaging quality.

Second embodiment

Referring to fig. 3, the optical imaging system 10 of the second embodiment includes, in order from an object side to an image side: the stop STO, the first lens L1 having a positive bending force, the second lens L2 having a positive bending force, the third lens L3 having a positive bending force, the fourth lens L4 having a negative bending force, and the filter L5.

The reference wavelength of the optical imaging system in the second embodiment is 940nm, and the optical imaging system 10 in the second embodiment has the following specific parameters, and the units of the Y radius, the thickness, and the half aperture are all millimeters (mm).

TABLE 3

TABLE 4

Number of noodles

S2

S3

S4

S5

S6

S7

S8

S9

R

1.6666E+00

2.3238E+00

3.1682E+00

4.8495E+00

-4.5035E+00

-1.1078E+00

2.7542E+00

9.7348E-01

K

-1.0266E+01

2.7913E+00

4.9052E-01

1.5134E+01

1.1617E+01

-3.0026E+00

-5.0000E+01

-7.3999E+00

A4

2.5310E-01

-3.0871E-02

-5.9275E-02

-4.4401E-02

3.0599E-02

2.2015E-02

-1.3306E-01

-1.1114E-01

A6

-2.6954E-01

-6.8224E-03

-4.5004E-02

-5.5286E-02

-9.3255E-02

-1.1700E-01

6.7542E-02

5.9362E-02

A8

2.8580E-01

-1.0745E-02

-3.3117E-02

-2.5306E-02

6.0982E-02

1.1050E-01

-8.6784E-03

-2.1487E-02

A10

-2.0496E-01

9.5968E-03

7.3789E-02

1.5177E-02

-1.8349E-02

-6.8600E-02

-3.5702E-03

4.0822E-03

A12

9.5111E-02

-1.1991E-02

-8.8698E-02

2.7644E-04

1.9096E-03

3.2840E-02

1.5985E-03

-1.6215E-04

A14

-2.5243E-02

-2.1299E-04

1.2097E-02

-1.3890E-02

-6.6917E-03

-7.4266E-03

-2.8658E-04

-7.6855E-05

A16

3.2086E-03

0.0000E+00

1.7080E-02

8.1902E-03

4.5734E-03

2.6177E-04

2.2481E-05

9.3923E-06

Fig. 4 shows a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the optical imaging system 10 of the second embodiment, wherein the longitudinal spherical aberration curves represent convergent focus deviations of less than 0.03mm after light rays with wavelengths of 920nm, 940nm and 960nm pass through the lenses of the optical imaging system 10 respectively; the astigmatism reference wavelengths are 920nm, 940nm and 960nm, and the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature, wherein the maximum values of the arc loss field curvature (corresponding to X in the figure) and the meridional field curvature (corresponding to Y in the figure) are less than 0.05 mm; the reference wavelength of distortion is 940nm, and the distortion curve represents the distortion magnitude values corresponding to different field angles, wherein the maximum distortion is less than 15%. As can be seen from fig. 4, the optical imaging system 10 according to the second embodiment can achieve good imaging quality.

Third embodiment

Referring to fig. 5, the optical imaging system 10 of the third embodiment includes, in order from an object side to an image side: the stop STO, the first lens L1 having a positive bending force, the second lens L2 having a positive bending force, the third lens L3 having a positive bending force, the fourth lens L4 having a negative bending force, and the filter L5.

The reference wavelength of the optical imaging system in the second embodiment is 940nm, and the optical imaging system 10 in the third embodiment has the following specific parameters, and the units of the Y radius, the thickness, and the half aperture are all millimeters (mm).

TABLE 5

TABLE 6

Number of noodles

S2

S3

S4

S5

S6

S7

S8

S9

R

2.3201E+00

2.9218E+00

2.8897E+00

7.2291E+00

-3.8587E+00

-1.3404E+00

2.6998E+00

1.0861E+00

K

-1.9671E+01

1.8577E+00

-9.9143E-01

-5.0000E+01

-2.3353E+00

-1.7534E+00

-1.3772E+01

-5.0408E+00

A4

1.6246E-01

-8.3340E-02

-6.1715E-02

1.2421E-03

7.4522E-02

9.6003E-02

-6.5213E-02

-4.7901E-02

A6

-2.4517E-01

9.9223E-03

8.4474E-03

-4.0581E-02

-7.6046E-02

-1.1678E-01

1.2181E-02

1.5938E-02

A8

2.7121E-01

-2.9426E-02

-7.1874E-02

3.9399E-03

4.6728E-02

1.0780E-01

1.6047E-03

-5.0283E-03

A10

-2.0881E-01

1.5661E-02

7.3859E-02

4.9765E-04

-2.0622E-02

-7.0892E-02

-2.6780E-03

1.1401E-03

A12

9.5384E-02

-4.4487E-03

-5.4949E-02

1.0026E-03

8.0063E-03

3.1561E-02

1.3610E-03

-1.9484E-04

A14

-2.3158E-02

4.7372E-04

2.5742E-02

2.1213E-04

-1.7289E-03

-7.4362E-03

-4.2448E-04

1.6045E-05

A16

2.0563E-03

0.0000E+00

-4.6541E-03

-1.6138E-04

1.1033E-04

6.7439E-04

5.1879E-05

-1.7547E-07

Fig. 6 shows a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the optical imaging system 10 of the third embodiment, wherein the longitudinal spherical aberration curves represent convergent focus deviations of less than 0.03mm after light rays with wavelengths of 920nm, 940nm and 960nm pass through the lenses of the optical imaging system 10 respectively; the astigmatism reference wavelengths are 920nm, 940nm and 960nm, and the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature, wherein the maximum values of the arc loss field curvature (corresponding to X in the figure) and the meridional field curvature (corresponding to Y in the figure) are less than 0.05 mm; the reference wavelength of distortion is 940nm, and the distortion curve represents the distortion magnitude values corresponding to different field angles, wherein the maximum distortion is less than 15%. As can be seen from fig. 6, the optical imaging system 10 according to the third embodiment can achieve good imaging quality.

Fourth embodiment

Referring to fig. 7, the optical imaging system 10 of the fourth embodiment includes, in order from an object side to an image side: the stop STO, the first lens L1 having a positive bending force, the second lens L2 having a positive bending force, the third lens L3 having a positive bending force, the fourth lens L4 having a negative bending force, and the filter L5.

The reference wavelength of the optical imaging system in the fourth embodiment is 940nm, and the optical imaging system 10 in the fourth embodiment has the following specific parameters, and the units of the Y radius, the thickness, and the half aperture are all millimeters (mm).

TABLE 7

It should be noted that EFL is the effective focal length of the optical imaging system 10, TTL is the total length of the optical imaging system 10, and FNO is the f-number of the optical imaging system 10. It is understood that in other embodiments, the material of the filter L5 is plastic.

TABLE 8

Number of noodles

S2

S3

S4

S5

S6

S7

S8

S9

R

2.1022E+00

2.6515E+00

3.0443E+00

1.2824E+01

-2.6846E+00

-1.0632E+00

2.5312E+00

0.919284013

K

-1.5471E+01

1.6576E+00

-7.4568E-01

-3.8049E+01

-2.3788E+00

-2.8795E+00

-1.7501E+01

-6.020273903

A4

1.7016E-01

-8.5241E-02

-6.0227E-02

-9.7233E-03

6.8157E-02

6.8813E-02

-7.6212E-02

-6.4374945E-02

A6

-2.4602E-01

7.4506E-03

-1.1590E-03

-4.6064E-02

-8.2767E-02

-1.2543E-01

1.9548E-02

2.2657386E-02

A8

2.7030E-01

-3.0801E-02

-7.5713E-02

1.7862E-03

4.5409E-02

1.1222E-01

-3.6227E-03

-6.9055938E-03

A10

-2.0861E-01

1.4502E-02

7.2513E-02

4.2183E-04

-1.9582E-02

-6.9722E-02

-3.2231E-03

9.1298270E-04

A12

9.5804E-02

-4.8579E-03

-5.5268E-02

1.1842E-03

8.7594E-03

3.1220E-02

1.8495E-03

-1.1538693E-04

A14

-2.3065E-02

9.1376E-04

2.6047E-02

2.1297E-04

-1.5691E-03

-7.5743E-03

-3.3810E-04

2.8063705E-05

A16

1.8238E-03

0.0000E+00

-4.2604E-03

-9.2304E-05

-3.5227E-05

7.7736E-04

-2.2406E-05

-3.9536643E-06

Fig. 8 shows a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the optical imaging system 10 of the fourth embodiment, wherein the longitudinal spherical aberration curves represent convergent focus deviations of less than 0.025mm after light rays with wavelengths of 920nm, 940nm and 960nm pass through the lenses of the optical imaging system 10 respectively; the astigmatism reference wavelengths are 920nm, 940nm and 960nm, and the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature, wherein the maximum values of the arc loss field curvature (corresponding to X in the figure) and the meridional field curvature (corresponding to Y in the figure) are less than 0.05 mm; the reference wavelength of distortion is 940nm, and the distortion curve represents the distortion magnitude values corresponding to different field angles, wherein the maximum distortion is less than 15%. As can be seen from fig. 8, the optical imaging system 10 according to the fourth embodiment can achieve good imaging quality.

Fifth embodiment

Referring to fig. 9, the optical imaging system 10 of the fifth embodiment includes, in order from an object side to an image side: the stop STO, the first lens L1 having a positive bending force, the second lens L2 having a positive bending force, the third lens L3 having a positive bending force, the fourth lens L4 having a negative bending force, and the filter L5.

The reference wavelength of the optical imaging system in the fifth embodiment is 940nm, and the optical imaging system 10 in the fifth embodiment has the following specific parameters, and the units of the Y radius, the thickness, and the half aperture are all millimeters (mm).

TABLE 9

Watch 10

Number of noodles

S2

S3

S4

S5

S6

S7

S8

S9

R

1.7339E+00

2.6628E+00

3.1304E+00

4.5509E+00

-2.3259E+00

-9.4331E-01

1.9739E+00

8.3673E-01

K

-1.2431E+01

3.1666E+00

-6.5710E+00

-6.0990E+00

-1.1519E+00

-3.0727E+00

-2.5429E+01

-7.4533E+00

A4

2.5518E-01

-4.4146E-02

-4.9153E-02

-1.9078E-02

3.9119E-02

2.2248E-02

-1.0129E-01

-1.0600E-01

A6

-2.9315E-01

-9.5146E-03

-2.8940E-02

-5.9153E-02

-6.5291E-02

-1.6406E-01

2.4610E-02

4.3636E-02

A8

3.0059E-01

-2.1657E-02

-7.3781E-02

-1.1910E-02

-7.5710E-02

1.6215E-01

1.3728E-02

-1.2083E-02

A10

-2.1077E-01

2.2573E-02

7.5441E-02

-3.3940E-03

9.0557E-02

-9.9713E-02

-8.5134E-03

1.7952E-03

A12

9.2110E-02

-2.3449E-02

-6.4896E-02

1.4677E-03

-5.1065E-03

3.0778E-02

3.2547E-04

-3.3649E-04

A14

-2.1551E-02

6.4297E-03

2.4435E-02

7.1516E-04

-6.3014E-02

6.1830E-04

4.7411E-04

6.8206E-05

A16

1.8074E-03

0.0000E+00

7.3572E-04

8.1227E-04

2.8559E-02

-6.1340E-04

-6.6916E-05

-6.8831E-06

Fig. 6 shows a longitudinal spherical aberration curve, an astigmatism curve and a distortion curve of the optical imaging system 10 of the fifth embodiment, wherein the longitudinal spherical aberration curves represent convergent focus deviations of less than 0.03mm after light rays with wavelengths of 920nm, 940nm and 960nm pass through the lenses of the optical imaging system 10 respectively; the astigmatism reference wavelengths are 920nm, 940nm and 960nm, and the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature, wherein the maximum values of the arc loss field curvature (corresponding to X in the figure) and the meridional field curvature (corresponding to Y in the figure) are less than 0.05 mm; the reference wavelength of distortion is 940nm, and the distortion curve represents the distortion magnitude values corresponding to different field angles, wherein the maximum distortion is less than 15%. As can be seen from fig. 10, the optical imaging system 10 according to the fifth embodiment can achieve good imaging quality.

Table 11 shows values of TTL/EFL, SAG21, SAG21/CT2, R5/EFL, SAG31/CT3, FNO, Vd, f2/f1, d23/d12 in the optical imaging systems 10 of the first to fifth embodiments.

Table 11

Referring to fig. 11, an image capturing module 100 is further provided in the present embodiment, including an optical imaging system 10, a photosensitive element 20 and a power device (not shown), where the photosensitive element 20 is disposed at an image side of the optical imaging system 10, and the power device is connected to the optical imaging system 10 to drive the optical imaging system 10 to move closer to or away from the photosensitive element 20 along an optical axis.

Specifically, the photosensitive element 20 may be a Complementary Metal Oxide Semiconductor (CMOS) image sensor or a Charge-coupled Device (CCD).

The image capturing module 100 further includes a housing 200; the image capturing module 100 is disposed in the housing 200.

Referring to fig. 12, an electronic device 500 is further provided in the present embodiment, including the image capturing module 100 and the body 400; the image capturing module 100 is disposed on the main body 400.

The electronic device 500 of the embodiment of the present application includes, but is not limited to, an imaging-enabled electronic device such as a smart phone, a tablet computer, a notebook computer, an electronic book reader, a Portable Multimedia Player (PMP), a portable phone, a video phone, a digital still camera, a mobile medical device, and a wearable device.

It will be evident to those skilled in the art that the application is not limited to the details of the foregoing illustrative embodiments, and that the present application may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present application and not for limiting, and although the present application is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solutions of the present application without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. An optical imaging system is characterized in that a diaphragm, a first lens with positive bending force, a second lens with positive bending force, a third lens with positive bending force and a fourth lens with negative bending force are arranged in sequence from an object side to an image side;

-1.5<R5/EFL<-0.3，-1.132<SAG31/CT3<-0.244；

wherein R5 is the curvature radius of the object side surface of the third lens at the optical axis, EFL is the effective focal length of the optical imaging system, SAG31 is the distance from the intersection point of the object side surface of the third lens and the optical axis to the maximum effective radius of the object side surface of the third lens in the direction parallel to the optical axis, and CT3 is the thickness of the third lens on the optical axis.

2. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

-0.2mm<SAG21<0mm；

3. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

-0.276<SAG21/CT2<-0.017；

4. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

TTL/EFL<1.6；

Wherein, TTL is a distance on an optical axis from an object side surface of the first lens element to an imaging surface of the optical imaging system, and EFL is an effective focal length of the optical imaging system.

5. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

FNO<1.4；

wherein FNO is the f-number of the optical imaging system.

6. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

Vd<30；

7. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

0.45<f2/f1<2.6；

8. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

1.5<d23/d12<3.4；

9. The optical imaging system of claim 1, wherein the second lens has at least one inflection point on both an object-side surface and an image-side surface, and wherein the fourth lens has at least one inflection point on both an object-side surface and an image-side surface.

10. An image capturing module, comprising:

a photosensitive element; and

the optical imaging system of any of claims 1-9, disposed on an object side of the photosensitive element.

11. An electronic device, comprising:

a body; and

the image capturing module as claimed in claim 10, disposed on the body.