CN216411710U

CN216411710U - Imaging system

Info

Publication number: CN216411710U
Application number: CN202123023173.XU
Authority: CN
Inventors: 王彦; 徐武超; 肖海东; 戴付建; 赵烈烽
Original assignee: Zhejiang Sunny Optics Co Ltd
Current assignee: Zhejiang Sunny Optics Co Ltd
Priority date: 2021-12-03
Filing date: 2021-12-03
Publication date: 2022-04-29
Anticipated expiration: 2031-12-03

Abstract

The utility model provides an imaging system. The imaging system sequentially comprises from the object side to the imaging side along the optical axis: a first lens having a negative focal power; a second lens having a positive refractive power; a third lens having a negative focal power; a fourth lens having a positive refractive power; a fifth lens having a negative focal power; the object side surface of the first lens is a concave surface; the object side surface of the third lens is a convex surface; the object side surface of the fourth lens is a concave surface, and the imaging side surface of the fourth lens is a convex surface; the effective focal length f of the imaging system and the entrance pupil diameter EPD of the imaging system satisfy: f/EPD < 1.9; the on-axis distance SL from the diaphragm to the imaging surface, the central thickness CT1 of the first lens on the optical axis, and the air interval T12 of the first lens and the second lens on the optical axis satisfy the following conditions: 2.5< SL/(CT1+ T12) < 3.0. The utility model solves the problem that the imaging system in the prior art has large aperture, ultra-wide angle and high pixel which are difficult to realize simultaneously.

Description

Imaging system

Technical Field

The utility model relates to the technical field of optical imaging equipment, in particular to an imaging system.

Background

With the popularization of smart phones, the requirements of people on the photographing effect of an imaging system on the smart phone are gradually improved, and meanwhile the imaging system is required to meet different photographing effects. At present, mainstream manufacturers generally carry a plurality of different types of imaging systems in mobile phones to ensure high image quality and unique shooting effect. In general. In order to meet the effects of wide field of view and large depth of field in shooting, an imaging system with an ultra-wide angle characteristic is indispensable; to meet the shooting effect of clear imaging details, a large-aperture lens is required. The prior art provides an imaging system applied to a mobile phone, which has a characteristic of large aperture, but the shooting range and the imaging quality are difficult to meet the actual requirements of users.

That is, the imaging system in the prior art has a problem that large aperture, ultra wide angle and high pixel are difficult to be simultaneously realized.

SUMMERY OF THE UTILITY MODEL

The utility model mainly aims to provide an imaging system to solve the problem that the imaging system in the prior art has large aperture, ultra-wide angle and high pixel which are difficult to realize simultaneously.

In order to achieve the above object, according to one aspect of the present invention, there is provided an imaging system comprising, in order from an object side to an imaging side along an optical axis: a first lens having a negative focal power; a second lens having a positive refractive power; a third lens having a negative focal power; a fourth lens having a positive refractive power; a fifth lens having a negative focal power; the object side surface of the first lens is a concave surface; the object side surface of the third lens is a convex surface; the object side surface of the fourth lens is a concave surface, and the imaging side surface of the fourth lens is a convex surface; the effective focal length f of the imaging system and the entrance pupil diameter EPD of the imaging system satisfy: f/EPD < 1.9; the on-axis distance SL from the diaphragm to the imaging surface, the central thickness CT1 of the first lens on the optical axis, and the air interval T12 of the first lens and the second lens on the optical axis satisfy the following conditions: 2.5< SL/(CT1+ T12) < 3.0.

Further, the effective focal length f of the imaging system and the maximum field angle FOV of the imaging system satisfy: 3.5mm < f tan (FOV/2) <6 mm.

Further, the effective focal length f1 of the first lens, the effective focal length f3 of the third lens and the effective focal length f5 of the fifth lens satisfy: 1.0< (f3+ f5)/f1< 1.5.

Further, the radius of curvature R7 of the object side of the fourth lens, the radius of curvature R8 of the imaging side of the fourth lens, and the effective focal length f4 of the fourth lens satisfy: 0.8< (R8-R7)/f4< 1.3.

Further, the radius of curvature R3 of the object side of the second lens, the radius of curvature R4 of the imaging side of the second lens, and the effective focal length f2 of the second lens satisfy: 2.1< (R3-R4)/f2< 2.7.

Further, a radius of curvature R5 of the object side surface of the third lens and a radius of curvature R6 of the imaging side surface of the third lens satisfy: 1.7< R5/R6< 2.5.

Further, a radius of curvature R9 of the object side surface of the fifth lens and a radius of curvature R10 of the imaging side surface of the fifth lens satisfy: 1.8< R9/R10< 2.6.

Further, the effective half caliber DT51 of the object side surface of the fifth lens and the effective half caliber DT21 of the object side surface of the second lens satisfy: 2.4< DT51/DT21< 3.2.

Further, the effective half aperture DT52 of the imaging side surface of the fifth lens and the effective half aperture DT11 of the object side surface of the first lens satisfy: 1.0< DT52/DT11< 1.5.

Further, a combined focal length f23 of the second lens and the third lens and a combined focal length f45 of the fourth lens and the fifth lens satisfy: 1.1< f45/f23< 1.8.

Further, the central thickness CT2 of the second lens on the optical axis and the edge thickness ET2 of the second lens satisfy: 1.5< CT2/ET2< 2.0.

Further, the edge thickness ET3 of the third lens, the edge thickness ET4 of the fourth lens and the edge thickness ET5 of the fifth lens satisfy: 1.0< (ET3+ ET4)/ET5< 1.6.

According to another aspect of the present invention, there is provided an imaging system including, in order from an object side to an imaging side along an optical axis: a first lens having a negative focal power; a second lens having a positive refractive power; a third lens having a negative focal power; a fourth lens having a positive refractive power; a fifth lens having a negative focal power; the object side surface of the first lens is a concave surface; the object side surface of the third lens is a convex surface; the object side surface of the fourth lens is a concave surface, and the imaging side surface of the fourth lens is a convex surface; the on-axis distance SL from the diaphragm to the imaging surface, the central thickness CT1 of the first lens on the optical axis, and the air interval T12 of the first lens and the second lens on the optical axis satisfy the following conditions: 2.5< SL/(CT1+ T12) < 3.0; the edge thickness ET3 of the third lens, the edge thickness ET4 of the fourth lens and the edge thickness ET5 of the fifth lens satisfy that: 1.0< (ET3+ ET4)/ET5< 1.6.

Further, the effective focal length f of the imaging system and the entrance pupil diameter EPD of the imaging system satisfy: f/EPD < 1.9; the curvature radius R7 of the object side surface of the fourth lens, the curvature radius R8 of the imaging side surface of the fourth lens and the effective focal length f4 of the fourth lens satisfy that: 0.8< (R8-R7)/f4< 1.3.

By applying the technical scheme of the utility model, the imaging system sequentially comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens from the object side to the imaging side along the optical axis, wherein the first lens has negative focal power; the second lens has positive focal power; the third lens has negative focal power; the fourth lens has positive focal power; the fifth lens has negative focal power; the object side surface of the first lens is a concave surface; the object side surface of the third lens is a convex surface; the object side surface of the fourth lens is a concave surface, and the imaging side surface of the fourth lens is a convex surface; the effective focal length f of the imaging system and the entrance pupil diameter EPD of the imaging system satisfy: f/EPD < 1.9; the on-axis distance SL from the diaphragm to the imaging surface, the central thickness CT1 of the first lens on the optical axis, and the air interval T12 of the first lens and the second lens on the optical axis satisfy the following conditions: 2.5< SL/(CT1+ T12) < 3.0.

By reasonably configuring the focal power and the surface type of each lens, the imaging quality of an imaging system is improved, and the imaging effect of high pixels is ensured. By restricting the ratio of the effective focal length F of the imaging system to the entrance pupil diameter EPD of the imaging system within a reasonable range, the F number of the imaging system is smaller than 1.9, which is beneficial to realizing the characteristic of large aperture. The expression of the curvature of field of the system can be reasonably controlled by restricting the relational expression among the axial distance SL from the diaphragm to the imaging surface, the central thickness CT1 of the first lens on the optical axis and the air interval T12 of the first lens and the second lens on the optical axis within a reasonable range, so that the aberration of the imaging system in an off-axis visual field is smaller. In addition, the imaging system has the characteristics of high pixel, ultra-wide angle and large aperture, and can better meet the imaging requirement.

Drawings

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

fig. 1 shows a schematic configuration diagram of an imaging system of example one of the present invention;

FIGS. 2-5 illustrate an on-axis chromatic aberration curve, an astigmatism curve, a distortion curve, and a magnification chromatic aberration curve, respectively, of the imaging system of FIG. 1;

fig. 6 is a schematic configuration diagram showing an imaging system of example two of the present invention;

FIGS. 7-10 illustrate on-axis chromatic aberration curves, astigmatism curves, distortion curves, and magnification chromatic aberration curves, respectively, of the imaging system of FIG. 6;

fig. 11 is a schematic configuration diagram showing an imaging system of example three of the present invention;

fig. 12 to 15 show an on-axis chromatic aberration curve, an astigmatism curve, a distortion curve, and a magnification chromatic aberration curve, respectively, of the imaging system in fig. 11;

fig. 16 is a schematic configuration diagram showing an imaging system of example four of the present invention;

fig. 17 to 20 show an on-axis chromatic aberration curve, an astigmatism curve, a distortion curve, and a magnification chromatic aberration curve, respectively, of the imaging system in fig. 16;

fig. 21 is a schematic structural view showing an imaging system of example five of the present invention;

fig. 22 to 25 show an on-axis chromatic aberration curve, an astigmatism curve, a distortion curve, and a magnification chromatic aberration curve, respectively, of the imaging system in fig. 21;

fig. 26 is a schematic structural view showing an imaging system of example six of the present invention;

fig. 27 to 30 show an on-axis chromatic aberration curve, an astigmatism curve, a distortion curve, and a chromatic aberration of magnification curve, respectively, of the imaging system in fig. 26.

Wherein the figures include the following reference numerals:

e1, first lens; s1, the object side surface of the first lens; s2, the imaging side surface of the first lens; STO, stop; e2, second lens; s3, an object side surface of the second lens; s4, the imaging side surface of the second lens; e3, third lens; s5, an object side surface of the third lens; s6, the imaging side surface of the third lens; e4, fourth lens; s7, an object side surface of the fourth lens; s8, the imaging side surface of the fourth lens; e5, fifth lens; s9, an object side surface of the fifth lens; s10, the imaging side surface of the fifth lens; e6, optical filters; s11, the object side of the optical filter; s12, imaging side face of the optical filter; and S13, imaging surface.

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 utility model.

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. When the R value is positive, the object side is judged to be convex, and when the R value is negative, the object side is judged to be concave; for the imaged side, when the R value is positive, it is determined to be concave, and when the R value is negative, it is determined to be convex.

The utility model provides an imaging system, aiming at solving the problem that an imaging system in the prior art has large aperture, ultra-wide angle and high pixel which are difficult to realize simultaneously.

Example one

As shown in fig. 1 to 30, the imaging system includes, in order from an object side to an imaging side along an optical axis, a first lens, a second lens, a third lens, a fourth lens, and a fifth lens, the first lens having a negative power; the second lens has positive focal power; the third lens has negative focal power; the fourth lens has positive focal power; the fifth lens has negative focal power; the object side surface of the first lens is a concave surface; the object side surface of the third lens is a convex surface; the object side surface of the fourth lens is a concave surface, and the imaging side surface of the fourth lens is a convex surface; the effective focal length f of the imaging system and the entrance pupil diameter EPD of the imaging system satisfy: f/EPD < 1.9; the on-axis distance SL from the diaphragm to the imaging surface, the central thickness CT1 of the first lens on the optical axis, and the air interval T12 of the first lens and the second lens on the optical axis satisfy the following conditions: 2.5< SL/(CT1+ T12) < 3.0.

Preferably 2.6< SL/(CT1+ T12) < 2.8.

In the present embodiment, the effective focal length f of the imaging system and the maximum field angle FOV of the imaging system satisfy: 3.5mm < f tan (FOV/2) <6 mm. By restricting the relation between the effective focal length f of the imaging system and the maximum field angle FOV of the imaging system within a reasonable range, the imaging effect of a large image plane can be realized, so that the imaging system is ensured to have a sufficiently large shooting range. In addition, the imaging system has the characteristics of high pixel, ultra-wide angle and large aperture, and can better meet the imaging requirement. Preferably, 3.7mm < f tan (FOV/2) <4.1 mm.

In the present embodiment, the effective focal length f1 of the first lens, the effective focal length f3 of the third lens, and the effective focal length f5 of the fifth lens satisfy: 1.0< (f3+ f5)/f1< 1.5. When the conditional expression is satisfied, the focal power of the system can be reasonably distributed, so that the positive spherical aberration and the negative spherical aberration among the first lens, the third lens and the fifth lens are mutually offset. Preferably, 1.1< (f3+ f5)/f1< 1.4.

In the present embodiment, the radius of curvature R7 of the object side surface of the fourth lens, the radius of curvature R8 of the imaging side surface of the fourth lens, and the effective focal length f4 of the fourth lens satisfy: 0.8< (R8-R7)/f4< 1.3. The method meets the conditional expression, can effectively control the astigmatism of the system, and further can improve the imaging quality of the off-axis field of view. Preferably, 1.0< (R8-R7)/f4< 1.2.

In the present embodiment, the radius of curvature R3 of the object side surface of the second lens, the radius of curvature R4 of the imaging side surface of the second lens, and the effective focal length f2 of the second lens satisfy: 2.1< (R3-R4)/f2< 2.7. The conditional expression is satisfied, so that the field curvature contribution amount of the second lens is in a reasonable range to balance the field curvature amount generated by the rear lens. Preferably, 2.4< (R3-R4)/f2< 2.5.

In the present embodiment, a radius of curvature R5 of the object side surface of the third lens and a radius of curvature R6 of the imaging side surface of the third lens satisfy: 1.7< R5/R6< 2.5. The conditional expression is satisfied, the sharing of the lateral large field of view of the object can be effectively realized, the correction capability of the subsequent lens on the off-axis aberration is improved, and a better imaging effect is obtained. Preferably, 1.9< R5/R6< 2.3.

In the present embodiment, a radius of curvature R9 of the object side surface of the fifth lens and a radius of curvature R10 of the imaging side surface of the fifth lens satisfy: 1.8< R9/R10< 2.6. The conditional expression is satisfied, the deflection angle of the system edge light can be reasonably controlled, and the sensitivity of the system is effectively reduced. Preferably, 2.0< R9/R10< 2.4.

In the present embodiment, the effective half aperture DT51 of the object side surface of the fifth lens and the effective half aperture DT21 of the object side surface of the second lens satisfy: 2.4< DT51/DT21< 3.2. The size of the lens can be reasonably distributed, the reasonability of the structure of the imaging system is ensured, and the processing and the assembly are easy. Preferably 2.7< DT51/DT21< 3.0.

In the present embodiment, the effective half aperture DT52 of the imaging side surface of the fifth lens and the effective half aperture DT11 of the object side surface of the first lens satisfy: 1.0< DT52/DT11< 1.5. The condition is satisfied, the front end size of the imaging system can be effectively reduced, and the lens screen occupation ratio is reduced. Preferably, 1.2< DT52/DT11< 1.4.

In the present embodiment, a combined focal length f23 of the second lens and the third lens and a combined focal length f45 of the fourth lens and the fifth lens satisfy: 1.1< f45/f23< 1.8. Satisfying this conditional expression, the contribution of the lens aberration in the imaging system can be balanced, and the aberration is in a reasonable level state. Preferably, 1.3< f45/f23< 1.7.

In the present embodiment, the central thickness CT2 of the second lens on the optical axis and the edge thickness ET2 of the second lens satisfy: 1.5< CT2/ET2< 2.0. By restraining the ratio of the central thickness CT2 of the second lens on the optical axis to the edge thickness ET2 of the second lens within a reasonable range, the second lens can be guaranteed to have good processing characteristics, and the total system length TTL of the imaging system can be guaranteed within a certain range, so that miniaturization is guaranteed. Preferably, 1.6< CT2/ET2< 1.8.

In the present embodiment, the edge thickness ET3 of the third lens, the edge thickness ET4 of the fourth lens, and the edge thickness ET5 of the fifth lens satisfy: 1.0< (ET3+ ET4)/ET5< 1.6. By constraining the relation among the edge thickness ET3 of the third lens, the edge thickness ET4 of the fourth lens and the edge thickness ET5 of the fifth lens within a reasonable range, on one hand, the distortion of the system can be reasonably controlled, and the imaging system has good distortion performance; on the other hand, ghost images in the system can be reasonably controlled, so that the imaging system has good optical performance. Preferably, 1.1< (ET3+ ET4)/ET5< 1.5.

Example two

As shown in fig. 1 to 30, the imaging system includes, in order from an object side to an imaging side along an optical axis, a first lens, a second lens, a third lens, a fourth lens, and a fifth lens, the first lens having a negative power; the second lens has positive focal power; the third lens has negative focal power; the fourth lens has positive focal power; the fifth lens has negative focal power; the object side surface of the first lens is a concave surface; the object side surface of the third lens is a convex surface; the object side surface of the fourth lens is a concave surface, and the imaging side surface of the fourth lens is a convex surface; the on-axis distance SL from the diaphragm to the imaging surface, the central thickness CT1 of the first lens on the optical axis, and the air interval T12 of the first lens and the second lens on the optical axis satisfy the following conditions: 2.5< SL/(CT1+ T12) < 3.0; the edge thickness ET3 of the third lens, the edge thickness ET4 of the fourth lens and the edge thickness ET5 of the fifth lens satisfy that: 1.0< (ET3+ ET4)/ET5< 1.6.

Preferably, 1.1< (ET3+ ET4)/ET5< 1.5.

By reasonably configuring the focal power and the surface type of each lens, the imaging quality of an imaging system is improved, and the imaging effect of high pixels is ensured. The expression of the curvature of field of the system can be reasonably controlled by restricting the relational expression among the axial distance SL from the diaphragm to the imaging surface, the central thickness CT1 of the first lens on the optical axis and the air interval T12 of the first lens and the second lens on the optical axis within a reasonable range, so that the aberration of the imaging system in an off-axis visual field is smaller. In addition, the imaging system has the characteristics of high pixel, ultra-wide angle and large aperture, and can better meet the imaging requirement. By constraining the relation among the edge thickness ET3 of the third lens, the edge thickness ET4 of the fourth lens and the edge thickness ET5 of the fifth lens within a reasonable range, on one hand, the distortion of the system can be reasonably controlled, and the imaging system has good distortion performance; on the other hand, ghost images in the system can be reasonably controlled, so that the imaging system has good optical performance. In addition, the imaging system has the characteristics of high pixel, ultra-wide angle and large aperture, and can better meet the imaging requirement.

In the present embodiment, the effective focal length f of the imaging system and the entrance pupil diameter EPD of the imaging system satisfy: f/EPD < 1.9. By restricting the ratio of the effective focal length F of the imaging system to the entrance pupil diameter EPD of the imaging system within a reasonable range, the F number of the imaging system is smaller than 1.9, which is beneficial to realizing the characteristic of large aperture.

The above-described imaging system may optionally further include a filter for correcting color deviation or a protective glass for protecting the photosensitive element on the imaging surface.

The imaging system in the present application may employ multiple lenses, such as the five lenses described above. By reasonably distributing the focal power and the surface shape of each lens, the central thickness of each lens, the on-axis distance between each lens and the like, the aperture of the imaging system can be effectively increased, the sensitivity of the lens is reduced, and the machinability of the lens is improved, so that the imaging system is more favorable for production and processing and can be suitable for portable electronic equipment such as smart phones. The left side is the object side and the right side is the imaging side.

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 making up the imaging system can be varied to achieve the various results and advantages described in this specification without departing from the claimed subject matter. For example, although five lenses are exemplified in the embodiment, the imaging system is not limited to including five lenses. The imaging system may also include other numbers of lenses, as desired.

Examples of specific surface types, parameters applicable to the imaging system of the above embodiment are further described below with reference to the drawings.

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

Example one

As shown in fig. 1 to 5, an imaging system of example one of the present application is described. Fig. 1 shows a schematic diagram of the configuration of an imaging system of example one.

As shown in fig. 1, the imaging system includes, in order from an object side to an imaging side: a first lens E1, a stop STO, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a filter E6, and an image forming surface S13.

The first lens E1 has negative power, and the object-side surface S1 of the first lens is a concave surface, and the image-side surface S2 of the first lens is a concave surface. The second lens E2 has positive refractive power, and the object side surface S3 of the second lens is a convex surface, and the image side surface S4 of the second lens is a convex surface. The third lens E3 has negative power, and the object-side surface S5 of the third lens is a convex surface and the image-side surface S6 of the third lens is a concave surface. The fourth lens E4 has positive refractive power, and the object-side surface S7 of the fourth lens is a concave surface and the image-side surface S8 of the fourth lens is a convex surface. The fifth lens E5 has negative power, and the object-side surface S9 of the fifth lens is a convex surface, and the image-side surface S10 of the fifth lens is a concave surface. The filter E6 has a filter object side surface S11 and a filter image side surface S12. The light from the object sequentially passes through the respective surfaces S1 to S12 and is finally imaged on the imaging surface S13.

In this example, the total effective focal length f of the imaging system is 2.19mm, the total system length TTL of the imaging system is 6.50mm and the image height ImgH is 3.69 mm.

Table 1 shows a basic structural parameter table of the imaging system 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 imaging side surface of any one of the first lens E1 to the fifth lens E5 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 coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28 and A30 that can be used for each of the aspherical mirrors S1-S10 in example one.

Flour mark

A4

A6

A8

A10

A12

A14

A16

S1

9.2363E-02

-2.6455E-02

-3.6335E-02

9.7411E-02

-1.2526E-01

1.0664E-01

-6.4163E-02

S2

1.8239E-01

-4.4416E-01

3.7253E+00

-2.1144E+01

8.0604E+01

-2.1619E+02

4.1994E+02

S3

-1.0827E-02

-2.2835E-01

4.8039E+00

-8.2228E+01

8.6473E+02

-5.6811E+03

2.3474E+04

S4

1.2316E-01

-2.5147E+00

3.2376E+01

-2.6339E+02

1.4491E+03

-5.5940E+03

1.5465E+04

S5

-2.3824E-01

-1.0238E+00

1.3069E+01

-8.8948E+01

4.1533E+02

-1.3969E+03

3.4515E+03

S6

-1.9459E-01

-1.3193E-01

2.8964E+00

-1.6905E+01

6.6499E+01

-1.8851E+02

3.9047E+02

S7

1.3473E-01

-1.5336E-01

1.9173E-01

-5.1015E-01

1.7940E+00

-4.1948E+00

6.4344E+00

S8

5.9629E-01

-1.9721E+00

4.9889E+00

-9.2303E+00

1.2605E+01

-1.2914E+01

1.0081E+01

S9

2.0714E-01

-1.4402E+00

3.7028E+00

-6.4411E+00

7.8570E+00

-6.8411E+00

4.3076E+00

S10

-4.5399E-01

5.1127E-01

-6.2745E-01

6.0811E-01

-4.2633E-01

2.1463E-01

-7.8240E-02

Flour mark

A18

A20

A22

A24

A26

A28

A30

S1

2.7892E-02

-8.8000E-03

1.9961E-03

-3.1720E-04

3.3510E-05

-2.1133E-06

6.0192E-08

S2

-5.9817E+02

6.2479E+02

-4.7268E+02

2.5182E+02

-8.9495E+01

1.9026E+01

-1.8283E+00

S3

-5.8672E+04

7.1782E+04

2.8337E+04

-2.4642E+05

3.8085E+05

-2.7139E+05

7.7220E+04

S4

-3.0923E+04

4.4708E+04

-4.6192E+04

3.3178E+04

-1.5697E+04

4.3851E+03

-5.4604E+02

S5

-6.3170E+03

8.5474E+03

-8.4353E+03

5.8978E+03

-2.7652E+03

7.7909E+02

-9.9614E+01

S6

-5.9356E+02

6.6005E+02

-5.2994E+02

2.9871E+02

-1.1204E+02

2.5091E+01

-2.5370E+00

S7

-6.7429E+00

4.9278E+00

-2.5145E+00

8.7900E-01

-2.0072E-01

2.6969E-02

-1.6166E-03

S8

-6.0421E+00

2.7710E+00

-9.5496E-01

2.3841E-01

-4.0463E-02

4.1508E-03

-1.9321E-04

S9

-1.9743E+00

6.5759E-01

-1.5723E-01

2.6264E-02

-2.9068E-03

1.9140E-04

-5.6728E-06

S10

2.0776E-02

-4.0129E-03

5.5714E-04

-5.4110E-05

3.4861E-06

-1.3372E-07

2.3090E-09

TABLE 2

Fig. 2 shows an on-axis chromatic aberration curve of the imaging system of example one, which represents the deviation of the convergent focus of light rays of different wavelengths after passing through the imaging system. Fig. 3 shows astigmatism curves of the imaging system of example one, which represent meridional field curvature and sagittal field curvature. Fig. 4 shows distortion curves of the imaging system of example one, which represent distortion magnitude values corresponding to different angles of view. Fig. 5 shows a chromatic aberration of magnification curve of the imaging system of example one, which represents the deviation of different image heights on the imaging plane after the light passes through the imaging system.

As can be seen from fig. 2 to 5, the imaging system of example one can achieve good imaging quality.

Example two

As shown in fig. 6 to 10, an imaging system 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. 6 shows a schematic diagram of the configuration of the imaging system of example two.

As shown in fig. 6, the imaging system includes, in order from an object side to an imaging side: a first lens E1, a stop STO, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a filter E6, and an image forming surface S13.

In this example, the total effective focal length f of the imaging system is 2.24mm, the total system length TTL of the imaging system is 6.50mm and the image height ImgH is 3.69 mm.

Table 3 shows a basic structural parameter table of the imaging system 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

9.2690E-02

-4.5240E-02

2.2623E-02

-7.6285E-03

-1.3124E-03

4.5232E-03

-3.8411E-03

S2

1.8886E-01

-5.5446E-01

4.5954E+00

-2.5618E+01

9.6469E+01

-2.5606E+02

4.9283E+02

S3

-3.1183E-02

7.7743E-01

-2.3504E+01

3.9546E+02

-4.3956E+03

3.4400E+04

-1.9528E+05

S4

1.2220E-01

-2.5650E+00

3.2475E+01

-2.5680E+02

1.3714E+03

-5.1523E+03

1.3905E+04

S5

-2.4955E-01

-7.2298E-01

9.3879E+00

-5.8196E+01

2.4172E+02

-7.2193E+02

1.5982E+03

S6

-2.0508E-01

9.7311E-02

7.0043E-01

-3.1724E+00

8.1884E+00

-1.5614E+01

2.4188E+01

S7

1.4259E-01

-2.6065E-01

6.8712E-01

-1.7980E+00

3.8061E+00

-5.9042E+00

6.6257E+00

S8

5.1270E-01

-1.5441E+00

3.5167E+00

-5.8630E+00

7.3529E+00

-7.1604E+00

5.5593E+00

S9

1.5451E-01

-1.1422E+00

2.7112E+00

-4.3238E+00

4.8860E+00

-3.9854E+00

2.3719E+00

S10

-4.4491E-01

4.2724E-01

-4.3914E-01

3.7661E-01

-2.4404E-01

1.1655E-01

-4.0953E-02

Flour mark

A18

A20

A22

A24

A26

A28

A30

S1

2.0210E-03

-7.3250E-04

1.8645E-04

-3.2831E-05

3.8132E-06

-2.6294E-07

8.1541E-09

S2

-6.9715E+02

7.2572E+02

-5.4971E+02

2.9478E+02

-1.0606E+02

2.2964E+01

-2.2613E+00

S3

8.1028E+05

-2.4429E+06

5.2637E+06

-7.8642E+06

7.7160E+06

-4.4620E+06

1.1509E+06

S4

-2.7211E+04

3.8565E+04

-3.9090E+04

2.7544E+04

-1.2774E+04

3.4928E+03

-4.2458E+02

S5

-2.6606E+03

3.3349E+03

-3.1065E+03

2.0852E+03

-9.5168E+02

2.6366E+02

-3.3373E+01

S6

-3.1534E+01

3.3748E+01

-2.7891E+01

1.6614E+01

-6.6014E+00

1.5530E+00

-1.6292E-01

S7

-5.3867E+00

3.1623E+00

-1.3232E+00

3.8363E-01

-7.2998E-02

8.1650E-03

-4.0464E-04

S8

-3.4643E+00

1.7032E+00

-6.3668E-01

1.7178E-01

-3.1133E-02

3.3623E-03

-1.6259E-04

S9

-1.0343E+00

3.2923E-01

-7.5471E-02

1.2109E-02

-1.2887E-03

8.1617E-05

-2.3262E-06

S10

1.0590E-02

-2.0055E-03

2.7423E-04

-2.6298E-05

1.6748E-06

-6.3493E-08

1.0825E-09

TABLE 4

Fig. 7 shows an on-axis chromatic aberration curve of the imaging system of example two, which represents the deviation of the convergent focus of light rays of different wavelengths after passing through the imaging system. Fig. 8 shows astigmatism curves of the imaging system of example two, which represent meridional field curvature and sagittal field curvature. Fig. 9 shows distortion curves of the imaging system of example two, which represent distortion magnitude values corresponding to different angles of view. Fig. 10 shows a chromatic aberration of magnification curve of the imaging system of example two, which represents the deviation of different image heights on the imaging plane after the light passes through the imaging system.

As can be seen from fig. 7 to 10, the imaging system of example two can achieve good imaging quality.

Example III

As shown in fig. 11 to 15, an imaging system of example three of the present application is described. Fig. 11 shows a schematic diagram of the configuration of an imaging system of example three.

As shown in fig. 11, the imaging system includes, in order from an object side to an imaging side: a first lens E1, a stop STO, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a filter E6, and an image forming surface S13.

The first lens E1 has negative power, and the object side surface S1 of the first lens is a concave surface and the image side surface S2 of the first lens is a convex surface. The second lens E2 has positive refractive power, and the object side surface S3 of the second lens is a convex surface, and the image side surface S4 of the second lens is a convex surface. The third lens E3 has negative power, and the object-side surface S5 of the third lens is a convex surface and the image-side surface S6 of the third lens is a concave surface. The fourth lens E4 has positive refractive power, and the object-side surface S7 of the fourth lens is a concave surface and the image-side surface S8 of the fourth lens is a convex surface. The fifth lens E5 has negative power, and the object-side surface S9 of the fifth lens is a convex surface, and the image-side surface S10 of the fifth lens is a concave surface. The filter E6 has a filter object side surface S11 and a filter image side surface S12. The light from the object sequentially passes through the respective surfaces S1 to S12 and is finally imaged on the imaging surface S13.

In this example, the total effective focal length f of the imaging system is 2.20mm, the total system length TTL of the imaging system is 6.46mm and the image height ImgH is 3.69 mm.

Table 5 shows a basic structural parameter table of the imaging system 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.

TABLE 6

Fig. 12 shows an on-axis chromatic aberration curve of the imaging system of example three, which represents the convergent focus deviation of light rays of different wavelengths after passing through the imaging system. Fig. 13 shows astigmatism curves of the imaging system of example three, which represent meridional field curvature and sagittal field curvature. Fig. 14 shows distortion curves of the imaging system of example three, which represent distortion magnitude values corresponding to different angles of view. Fig. 15 shows a chromatic aberration of magnification curve of the imaging system of example three, which represents the deviation of different image heights on the imaging plane after the light passes through the imaging system.

As can be seen from fig. 12 to 15, the imaging system given in example three can achieve good imaging quality.

Example four

As shown in fig. 16 to 20, an imaging system of example four of the present application is described. Fig. 16 shows a schematic diagram of the configuration of an imaging system of example four.

As shown in fig. 16, the imaging system includes, in order from the object side to the imaging side: a first lens E1, a stop STO, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a filter E6, and an image forming surface S13.

In this example, the total effective focal length f of the imaging system is 2.08mm, the total system length TTL of the imaging system is 6.50mm and the image height ImgH is 3.69 mm.

Table 7 shows a basic structural parameter table of the imaging system 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

8.6243E-02

1.6152E-02

-1.4651E-01

2.6672E-01

-2.9651E-01

2.2573E-01

-1.2236E-01

S2

1.8249E-01

-5.7813E-01

5.3151E+00

-3.1418E+01

1.2278E+02

-3.3352E+02

6.4830E+02

S3

1.2272E-02

-1.1304E+00

2.2341E+01

-2.9966E+02

2.6497E+03

-1.5385E+04

5.6523E+04

S4

1.1952E-01

-2.4737E+00

3.0307E+01

-2.3062E+02

1.1778E+03

-4.1890E+03

1.0558E+04

S5

-2.3846E-01

-8.6184E-01

9.6160E+00

-5.6171E+01

2.2599E+02

-6.6243E+02

1.4544E+03

S6

-2.0830E-01

3.3487E-01

-2.1019E+00

1.3744E+01

-5.7344E+01

1.6075E+02

-3.1660E+02

S7

9.4036E-02

3.5977E-01

-2.5199E+00

8.3719E+00

-1.7875E+01

2.6392E+01

-2.7656E+01

S8

5.8224E-01

-1.8531E+00

4.5224E+00

-8.3008E+00

1.1677E+01

-1.2754E+01

1.0859E+01

S9

2.2749E-01

-1.3683E+00

3.2184E+00

-5.1108E+00

5.7165E+00

-4.5900E+00

2.6786E+00

S10

-4.1257E-01

4.0401E-01

-4.5185E-01

4.1579E-01

-2.8326E-01

1.4044E-01

-5.0833E-02

Flour mark

A18

A20

A22

A24

A26

A28

A30

S1

4.8020E-02

-1.3684E-02

2.8042E-03

-4.0264E-04

3.8448E-05

-2.1928E-06

5.6516E-08

S2

-9.1405E+02

9.3635E+02

-6.8964E+02

3.5570E+02

-1.2190E+02

2.4926E+01

-2.3007E+00

S3

-1.1305E+05

1.3832E+04

5.7428E+05

-1.6161E+06

2.2066E+06

-1.5766E+06

4.7206E+05

S4

-1.8956E+04

2.4049E+04

-2.1027E+04

1.2008E+04

-3.9893E+03

5.5424E+02

1.6026E+01

S5

-2.4300E+03

3.0964E+03

-2.9657E+03

2.0626E+03

-9.7851E+02

2.8173E+02

-3.6963E+01

S6

4.4743E+02

-4.5614E+02

3.3263E+02

-1.6919E+02

5.7012E+01

-1.1436E+01

1.0335E+00

S7

2.0729E+01

-1.1053E+01

4.1055E+00

-1.0153E+00

1.5263E-01

-1.1284E-02

1.7575E-04

S8

-7.1563E+00

3.5935E+00

-1.3412E+00

3.5823E-01

-6.4402E-02

6.9545E-03

-3.3984E-04

S9

-1.1422E+00

3.5487E-01

-7.9296E-02

1.2392E-02

-1.2840E-03

7.9165E-05

-2.1970E-06

S10

1.3469E-02

-2.6033E-03

3.6200E-04

-3.5184E-05

2.2628E-06

-8.6274E-08

1.4718E-09

TABLE 8

Fig. 17 shows an on-axis chromatic aberration curve of the imaging system of example four, which represents the convergent focus deviation of light rays of different wavelengths after passing through the imaging system. Fig. 18 shows astigmatism curves of the imaging system of example four, which represent meridional field curvature and sagittal field curvature. Fig. 19 shows distortion curves of the imaging system of example four, which represent distortion magnitude values corresponding to different angles of view. Fig. 20 shows a chromatic aberration of magnification curve of the imaging system of example four, which represents the deviation of different image heights on the imaging plane after the light passes through the imaging system.

As can be seen from fig. 17 to 20, the imaging system given in example four can achieve good imaging quality.

Example five

As shown in fig. 21 to 25, an imaging system of example five of the present application is described. Fig. 21 shows a schematic diagram of the imaging system configuration of example five.

As shown in fig. 21, the imaging system includes, in order from the object side to the imaging side: a first lens E1, a stop STO, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a filter E6, and an image forming surface S13.

In this example, the total effective focal length f of the imaging system is 2.20mm, the total system length TTL of the imaging system is 6.50mm and the image height ImgH is 3.69 mm.

Table 9 shows a basic structural parameter table of the imaging system 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

9.5385E-02

-4.8202E-02

2.4993E-02

-9.5516E-03

1.5019E-03

3.5114E-04

2.7557E-04

S2

2.0044E-01

-7.3137E-01

5.9204E+00

-3.1831E+01

1.1574E+02

-2.9655E+02

5.4939E+02

S3

-2.5694E-03

-5.4984E-01

1.1544E+01

-1.8393E+02

1.9668E+03

-1.3898E+04

6.4911E+04

S4

1.2406E-01

-2.5403E+00

3.2612E+01

-2.6417E+02

1.4464E+03

-5.5560E+03

1.5280E+04

S5

-2.3154E-01

-1.0880E+00

1.3689E+01

-9.3037E+01

4.3389E+02

-1.4555E+03

3.5798E+03

S6

-1.9447E-01

-8.4878E-02

2.1976E+00

-1.1534E+01

4.0524E+01

-1.0333E+02

1.9381E+02

S7

1.3499E-01

-1.5729E-01

1.2939E-01

1.0184E-01

-6.1666E-01

1.3735E+00

-2.0062E+00

S8

5.9035E-01

-1.9177E+00

4.8072E+00

-9.0181E+00

1.2891E+01

-1.4263E+01

1.2284E+01

S9

2.1473E-01

-1.4445E+00

3.6009E+00

-6.0722E+00

7.2165E+00

-6.1577E+00

3.8191E+00

S10

-4.5023E-01

4.7295E-01

-5.3335E-01

4.8224E-01

-3.1935E-01

1.5285E-01

-5.3103E-02

Flour mark

A18

A20

A22

A24

A26

A28

A30

S1

-6.2967E-04

4.1241E-04

-1.4927E-04

3.3261E-05

-4.5603E-06

3.5444E-07

-1.1987E-08

S2

-7.4452E+02

7.3789E+02

-5.2826E+02

2.6556E+02

-8.8787E+01

1.7696E+01

-1.5878E+00

S3

-1.9882E+05

3.8287E+05

-3.9683E+05

4.1926E+04

4.0663E+05

-4.4418E+05

1.5727E+05

S4

-3.0377E+04

4.3640E+04

-4.4769E+04

3.1900E+04

-1.4960E+04

4.1387E+03

-5.0985E+02

S5

-6.5069E+03

8.7240E+03

-8.5144E+03

5.8776E+03

-2.7173E+03

7.5407E+02

-9.4880E+01

S6

-2.6794E+02

2.7181E+02

-1.9957E+02

1.0311E+02

-3.5526E+01

7.3246E+00

-6.8326E-01

S7

2.0644E+00

-1.5192E+00

7.9425E-01

-2.8773E-01

6.8606E-02

-9.6772E-03

6.1149E-04

S8

-8.1768E+00

4.1333E+00

-1.5442E+00

4.0995E-01

-7.2695E-02

7.6849E-03

-3.6505E-04

S9

-1.7312E+00

5.7203E-01

-1.3601E-01

2.2630E-02

-2.4982E-03

1.6423E-04

-4.8634E-06

S10

1.3440E-02

-2.4699E-03

3.2523E-04

-2.9816E-05

1.8019E-06

-6.4300E-08

1.0218E-09

Watch 10

Fig. 22 shows an on-axis chromatic aberration curve of the imaging system of example five, which represents the convergent focus deviation of light rays of different wavelengths after passing through the imaging system. Fig. 23 shows astigmatism curves of the imaging system of example five, which represent meridional field curvature and sagittal field curvature. Fig. 24 shows distortion curves of the imaging system of example five, which represent distortion magnitude values corresponding to different angles of view. Fig. 25 shows a chromatic aberration of magnification curve of the imaging system of example five, which represents the deviation of different image heights on the imaging plane after the light passes through the imaging system.

As can be seen from fig. 22 to 25, the imaging system given in example five can achieve good imaging quality.

Example six

As shown in fig. 26 to 30, an imaging system of example six of the present application is described. Fig. 26 shows a schematic diagram of an imaging system configuration of example six.

As shown in fig. 26, the imaging system includes, in order from the object side to the imaging side: a first lens E1, a stop STO, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a filter E6, and an image forming surface S13.

Table 11 shows a basic structural parameter table of the imaging system of example six, in which the units of the radius of curvature, thickness/distance, focal length, and effective radius are all millimeters (mm).

TABLE 11

Table 12 shows the high-order term coefficients that can be used for each of the aspherical mirror surfaces in example six, wherein each aspherical mirror surface type can be defined by formula (1) given in example one above.

TABLE 12

Fig. 27 shows an on-axis chromatic aberration curve of the imaging system of example six, which represents the convergent focus deviation of light rays of different wavelengths after passing through the imaging system. Fig. 28 shows astigmatism curves representing meridional field curvature and sagittal field curvature of the imaging system of example six. Fig. 29 shows distortion curves of the imaging system of example six, which represent distortion magnitude values corresponding to different angles of view. Fig. 30 shows a chromatic aberration of magnification curve of the imaging system of example six, which represents the deviation of different image heights on the imaging plane after the light passes through the imaging system.

As can be seen from fig. 27 to 30, the imaging system given in example six can achieve good imaging quality.

To sum up, examples one to six satisfy the relationships shown in table 13, respectively.

Conditional formula/example	1	2	3	4	5	6
							f/EPD	1.84	1.89	1.85	1.83	1.86	1.88
f*tan(FOV/2)(mm)	3.90	4.03	4.02	3.73	3.96	4.06
							(f3+f5)/f1	1.23	1.25	1.14	1.31	1.22	1.13
(R8-R7)/f4	1.12	1.06	1.14	1.13	1.12	1.11
							(R3-R4)/f2	2.46	2.46	2.44	2.42	2.43	2.42
R5/R6	2.06	1.99	2.05	2.07	2.08	2.25
							R9/R10	2.31	2.24	2.32	2.09	2.34	2.29
DT51/DT21	2.77	2.83	2.80	2.93	2.79	2.88
							DT52/DT11	1.28	1.30	1.24	1.23	1.28	1.31
SL/(CT1+T12)	2.75	2.77	2.72	2.62	2.74	2.75
							f45/f23	1.55	1.65	1.61	1.35	1.55	1.55
CT2/ET2	1.68	1.69	1.71	1.70	1.69	1.71
							(ET3+ET4)/ET5	1.22	1.18	1.23	1.43	1.20	1.20

Table 13 table 14 gives effective focal lengths f of the imaging systems of example one to example six, effective focal lengths f1 to f5 of the respective lenses, and the like.

TABLE 14

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 apparatus is equipped with the imaging system 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 imaging system, comprising in order from an object side to an imaging side along an optical axis:

a first lens having a negative optical power;

a second lens having a positive optical power;

a third lens having a negative optical power;

a fourth lens having a positive optical power;

a fifth lens having a negative optical power;

the object side surface of the first lens is a concave surface; the object side surface of the third lens is a convex surface; the object side surface of the fourth lens is a concave surface, and the imaging side surface of the fourth lens is a convex surface;

the effective focal length f of the imaging system and the entrance pupil diameter EPD of the imaging system satisfy: f/EPD < 1.9; the on-axis distance SL from the diaphragm to the imaging surface, the central thickness CT1 of the first lens on the optical axis, and the air interval T12 of the first lens and the second lens on the optical axis satisfy: 2.5< SL/(CT1+ T12) < 3.0.

2. The imaging system of claim 1, wherein an effective focal length f of the imaging system and a maximum field of view FOV of the imaging system satisfy: 3.5mm < f tan (FOV/2) <6 mm.

3. The imaging system of claim 1, wherein an effective focal length f1 of the first lens, an effective focal length f3 of the third lens, and an effective focal length f5 of the fifth lens satisfy: 1.0< (f3+ f5)/f1< 1.5.

4. The imaging system of claim 1, wherein a radius of curvature of an object side of the fourth lens, R7, a radius of curvature of an imaging side of the fourth lens, R8, and an effective focal length f4 of the fourth lens, satisfy: 0.8< (R8-R7)/f4< 1.3.

5. The imaging system of claim 1, wherein the radius of curvature of the object side of the second lens, R3, the radius of curvature of the imaging side of the second lens, R4, and the effective focal length of the second lens, f2, satisfy: 2.1< (R3-R4)/f2< 2.7.

6. The imaging system of claim 1, wherein a radius of curvature R5 of the object-side surface of the third lens and a radius of curvature R6 of the imaging-side surface of the third lens satisfy: 1.7< R5/R6< 2.5.

7. The imaging system of claim 1, wherein a radius of curvature R9 of the object side of the fifth lens and a radius of curvature R10 of the imaging side of the fifth lens satisfy: 1.8< R9/R10< 2.6.

8. The imaging system of claim 1, wherein an effective half aperture ratio DT51 of the object side surface of the fifth lens and an effective half aperture ratio DT21 of the object side surface of the second lens satisfy: 2.4< DT51/DT21< 3.2.

9. The imaging system of claim 1, wherein an effective half aperture DT52 of the imaging side surface of the fifth lens and an effective half aperture DT11 of the object side surface of the first lens satisfy: 1.0< DT52/DT11< 1.5.

10. The imaging system of claim 1, wherein a combined focal length f23 of the second and third lenses and a combined focal length f45 of the fourth and fifth lenses satisfies: 1.1< f45/f23< 1.8.

11. The imaging system of claim 1, wherein a center thickness CT2 of the second lens on the optical axis and an edge thickness ET2 of the second lens satisfy: 1.5< CT2/ET2< 2.0.

12. The imaging system of claim 1, wherein an edge thickness ET3 of the third lens, an edge thickness ET4 of the fourth lens, and an edge thickness ET5 of the fifth lens satisfy: 1.0< (ET3+ ET4)/ET5< 1.6.

13. An imaging system, comprising in order from an object side to an imaging side along an optical axis:

a first lens having a negative optical power;

a second lens having a positive optical power;

a third lens having a negative optical power;

a fourth lens having a positive optical power;

a fifth lens having a negative optical power;

the on-axis distance SL from the diaphragm to the imaging surface, the central thickness CT1 of the first lens on the optical axis, and the air interval T12 of the first lens and the second lens on the optical axis satisfy: 2.5< SL/(CT1+ T12) < 3.0; the edge thickness ET3 of the third lens, the edge thickness ET4 of the fourth lens and the edge thickness ET5 of the fifth lens satisfy that: 1.0< (ET3+ ET4)/ET5< 1.6.

14. The imaging system of claim 13, wherein an effective focal length f of the imaging system and a maximum field of view FOV of the imaging system satisfy: 3.5mm < f tan (FOV/2) <6 mm.

15. The imaging system of claim 13, wherein an effective focal length f1 of the first lens, an effective focal length f3 of the third lens, and an effective focal length f5 of the fifth lens satisfy: 1.0< (f3+ f5)/f1< 1.5.

16. The imaging system of claim 13, wherein an effective focal length f of the imaging system and an entrance pupil diameter EPD of the imaging system satisfy: f/EPD < 1.9; the radius of curvature R7 of the object side of the fourth lens, the radius of curvature R8 of the imaging side of the fourth lens and the effective focal length f4 of the fourth lens satisfy: 0.8< (R8-R7)/f4< 1.3.

17. The imaging system of claim 13, wherein the radius of curvature of the object side of the second lens, R3, the radius of curvature of the imaging side of the second lens, R4, and the effective focal length of the second lens, f2, satisfy: 2.1< (R3-R4)/f2< 2.7.

18. The imaging system of claim 13, wherein a radius of curvature R5 of the object-side surface of the third lens and a radius of curvature R6 of the imaging-side surface of the third lens satisfy: 1.7< R5/R6< 2.5.

19. The imaging system of claim 13, wherein a radius of curvature R9 of the object side of the fifth lens and a radius of curvature R10 of the imaging side of the fifth lens satisfy: 1.8< R9/R10< 2.6.

20. The imaging system of claim 13, wherein an effective half aperture ratio DT51 of the object side surface of the fifth lens and an effective half aperture ratio DT21 of the object side surface of the second lens satisfy: 2.4< DT51/DT21< 3.2.

21. The imaging system of claim 13, wherein an effective half aperture DT52 of the imaging side surface of the fifth lens and an effective half aperture DT11 of the object side surface of the first lens satisfy: 1.0< DT52/DT11< 1.5.

22. The imaging system of claim 13, wherein a combined focal length f23 of the second and third lenses and a combined focal length f45 of the fourth and fifth lenses satisfies: 1.1< f45/f23< 1.8.

23. The imaging system of claim 13, wherein a center thickness CT2 of the second lens on the optical axis and an edge thickness ET2 of the second lens satisfy: 1.5< CT2/ET2< 2.0.