CN114637095A - Imaging system - Google Patents

Abstract

The invention provides an imaging system. The imaging system comprises from the light inlet side to the light outlet side: a first lens having refractive power; the surface of the second lens close to the light-in side is a convex surface, and the surface of the second lens close to the light-out side is a concave surface; a third lens having refractive power; the on-axis distance TTL from the surface of the first lens close to the light incidence side to the imaging surface of the imaging system and the half ImgH of the diagonal length of the effective pixel area on the imaging surface satisfy the following condition: TTL/ImgH < 1.6. The invention solves the problem that the lens in the prior art is difficult to miniaturize.

Description

Imaging system

Technical Field

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

Background

In recent years, with the continuous upgrading and upgrading of electronic products such as mobile terminals, users have increasingly demanded diversified functions of the products, and further, demands for lenses mounted on the mobile terminals have also increased, and not only higher performance but also miniaturization of the lenses are required.

That is, the lens in the prior art has a problem that miniaturization is difficult.

Disclosure of Invention

The invention mainly aims to provide an imaging system to solve the problem that in the prior art, a lens is difficult to miniaturize.

In order to achieve the above object, according to one aspect of the present invention, there is provided an imaging system comprising, from a light-in side to a light-out side: a first lens having refractive power; the surface of the second lens close to the light-in side is a convex surface, and the surface of the second lens close to the light-out side is a concave surface; a third lens having refractive power; the on-axis distance TTL from the surface of the first lens close to the light incidence side to the imaging surface of the imaging system and the half ImgH of the diagonal length of the effective pixel area on the imaging surface satisfy the following condition: TTL/ImgH < 1.6.

Further, the effective focal length f3 of the third lens and the curvature radius R5 of the surface of the third lens close to the light inlet side satisfy that: f3/R5< 1.0.

Further, an on-axis distance TTL from the surface of the first lens close to the light entrance side to the imaging plane and an entrance pupil diameter EPD of the imaging system satisfy: 2.5< TTL/EPD < 3.5.

Further, the height Do of the object and the minimum on-axis distance TOL of the object to the surface of the first lens close to the light incidence side satisfy: 0.6< Do/TOL < 1.2.

Further, the maximum half field angle Semi-FOV of the imaging system satisfies: Semi-FOV > 35.

Further, the effective focal length f1 of the first lens and the effective focal length f2 of the second lens satisfy: f1/f2> -0.8.

Further, the combined focal length f12 of the first lens and the second lens and the combined focal length f23 of the second lens and the third lens satisfy the following conditions: 0.4< f12/f23< 1.0.

Further, the curvature radius R1 of the surface of the first lens close to the light inlet side and the curvature radius R2 of the surface of the first lens close to the light outlet side satisfy that: R1/R2< 2.5.

Further, the curvature radius R3 of the surface of the second lens close to the light inlet side and the curvature radius R4 of the surface of the second lens close to the light outlet side satisfy that: l (R3-R4)/(R3+ R4) | < 0.8.

Further, a central thickness CT1 of the first lens on the optical axis of the imaging system and a central thickness CT3 of the third lens on the optical axis satisfy: 0.4< CT1/CT3< 1.2.

Further, the first lens and the second lens satisfy, between an air interval T12 on the optical axis of the imaging system, a sum Σ AT of air intervals on the optical axis between any adjacent two lenses having refractive power among the first lens to the third lens: 0.3< T12/∑ AT < 0.9.

Further, the center thickness CT2 of the second lens on the optical axis of the imaging system, the air interval T23 of the second lens and the third lens on the optical axis, and the effective focal length f of the imaging system satisfy: (CT2+ T23)/f < 0.5.

Further, an axial distance SAG31 between an intersection point of a surface of the third lens close to the light entrance side and the optical axis of the imaging system and an effective radius vertex of the surface of the third lens close to the light entrance side, and an axial distance SAG32 between an intersection point of the surface of the third lens close to the light exit side and the optical axis and an effective radius vertex of the surface of the third lens close to the light exit side satisfy: 0.4< (SAG31+ SAG32)/SAG32< 1.0.

Further, an on-axis distance SAG21 from the intersection point of the surface of the second lens close to the light-in side and the optical axis of the imaging system to the effective radius vertex of the surface of the second lens close to the light-in side, and an on-axis distance SAG22 from the intersection point of the surface of the second lens close to the light-out side and the optical axis to the effective radius vertex of the surface of the second lens close to the light-out side satisfy: (SAG21-SAG22)/(SAG21+ SAG22) < 0.7.

Further, the effective half aperture DT11 of the surface of the first lens close to the light inlet side, the effective half aperture DT21 of the surface of the second lens close to the light inlet side and the effective half aperture DT31 of the surface of the third lens close to the light inlet side satisfy the following conditions: 0.5< (DT11+ DT21)/DT31< 1.2.

Further, a distance BFL from the surface of the third lens close to the light-emitting side to the imaging plane on the optical axis of the imaging system and an on-axis distance SD from the aperture of the imaging system to the surface of the third lens close to the light-emitting side satisfy the following conditions: 0.4< BFL/SD < 1.0.

According to another aspect of the present invention, there is provided an imaging system comprising, from a light-in side to a light-out side: a first lens having refractive power; the surface of the second lens close to the light-in side is a convex surface, and the surface of the second lens close to the light-out side is a concave surface; a third lens having refractive power; the on-axis distance TTL from the surface of the first lens close to the light incidence side to the imaging surface and the entrance pupil diameter EPD of the imaging system satisfy the following conditions: 2.5< TTL/EPD < 3.5.

Further, the effective focal length f3 of the third lens and the curvature radius R5 of the surface of the third lens close to the light inlet side satisfy that: f3/R5< 1.0.

Further, the height Do of the object and the minimum on-axis distance TOL of the object to the surface of the first lens close to the light incidence side satisfy: 0.6< Do/TOL < 1.2.

Further, the maximum half field angle Semi-FOV of the imaging system satisfies: Semi-FOV > 35.

Further, the effective focal length f1 of the first lens and the effective focal length f2 of the second lens satisfy: f1/f2> -0.8.

Further, the combined focal length f12 of the first lens and the second lens and the combined focal length f23 of the second lens and the third lens satisfy the following conditions: 0.4< f12/f23< 1.0.

Further, the curvature radius R1 of the surface of the first lens close to the light inlet side and the curvature radius R2 of the surface of the first lens close to the light outlet side satisfy that: R1/R2< 2.5.

Further, the curvature radius R3 of the surface of the second lens close to the light inlet side and the curvature radius R4 of the surface of the second lens close to the light outlet side satisfy that: l (R3-R4)/(R3+ R4) | < 0.8.

Further, a center thickness CT1 of the first lens on an optical axis of the imaging system and a center thickness CT3 of the third lens on the optical axis satisfy: 0.4< CT1/CT3< 1.2.

Further, the first lens and the second lens satisfy, between an air interval T12 on the optical axis of the imaging system, a sum Σ AT of air intervals on the optical axis between any adjacent two lenses having refractive power among the first lens to the third lens: 0.3< T12/sigma AT < 0.9.

Further, the center thickness CT2 of the second lens on the optical axis of the imaging system, the air interval T23 of the second lens and the third lens on the optical axis, and the effective focal length f of the imaging system satisfy: (CT2+ T23)/f < 0.5.

Further, an on-axis distance SAG31 from an intersection point of a surface of the third lens close to the light-in side and the optical axis of the imaging system to an effective radius vertex of the surface of the third lens close to the light-in side, and an on-axis distance SAG32 from an intersection point of the surface of the third lens close to the light-out side and the optical axis to an effective radius vertex of the surface of the third lens close to the light-out side satisfy: 0.4< (SAG31+ SAG32)/SAG32< 1.0.

Further, an on-axis distance SAG21 from the intersection point of the surface of the second lens close to the light-in side and the optical axis of the imaging system to the effective radius vertex of the surface of the second lens close to the light-in side, and an on-axis distance SAG22 from the intersection point of the surface of the second lens close to the light-out side and the optical axis to the effective radius vertex of the surface of the second lens close to the light-out side satisfy: (SAG21-SAG22)/(SAG21+ SAG22) < 0.7.

Further, the effective half aperture DT11 of the surface of the first lens close to the light inlet side, the effective half aperture DT21 of the surface of the second lens close to the light inlet side and the effective half aperture DT31 of the surface of the third lens close to the light inlet side satisfy the following conditions: 0.5< (DT11+ DT21)/DT31< 1.2.

Further, a distance BFL from the surface of the third lens close to the light-emitting side to the imaging plane on the optical axis of the imaging system and an on-axis distance SD from the aperture of the imaging system to the surface of the third lens close to the light-emitting side satisfy the following conditions: 0.4< BFL/SD < 1.0.

By applying the technical scheme of the invention, the imaging system comprises a first lens, a second lens and a third lens from the light-in side to the light-out side. The first lens has a refractive power; the second lens has negative refractive power, the surface of the second lens close to the light-in side is a convex surface, and the surface of the second lens close to the light-out side is a concave surface; the third lens has refractive power; the on-axis distance TTL from the surface of the first lens close to the light incidence side to the imaging surface of the imaging system and the half ImgH of the diagonal length of the effective pixel area on the imaging surface satisfy the following condition: TTL/ImgH < 1.6.

By distributing the refractive power of partial lenses of the imaging system and designing the surface type of the lenses, the low-order aberration of the imaging system can be effectively balanced, meanwhile, the tolerance sensitivity of the imaging system can be reduced, and the imaging quality of the imaging system is ensured while the miniaturization of the imaging system is kept. And the refractive power and the surface type of the second lens are reasonably controlled, so that the low-order aberration of the imaging system is favorably controlled. By controlling the ratio of the total length to the image height of the imaging system, the total size of the imaging system can be effectively reduced, and the ultra-thin characteristic and the miniaturization of the imaging system are realized.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiment(s) of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 shows a schematic configuration of an imaging system of a first example 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;

7-10 show on-axis chromatic aberration curves, astigmatism curves, distortion curves, and chromatic aberration of magnification curves, respectively, for 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:

STO, stop; e1, first lens; s1, the surface of the first lens close to the light incidence side; s2, the surface of the first lens close to the light-emitting side; e2, second lens; s3, the surface of the second lens close to the light incidence side; s4, enabling the second lens to be close to the surface of the light emitting side; e3, third lens; s5, the surface of the third lens close to the light incidence side; s6, the surface of the third lens close to the light-emitting side; e4, a filter plate; s7, the surface of the filter close to the light incident side; s8, enabling the filter to be close to the surface of the light emergent side; and S9, 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 invention.

It should be noted that in this specification, the expressions first, second, third, etc. are used only to distinguish one feature from another, and do not represent any limitation on the features. Thus, the first lens discussed below may also be referred to as the second lens or the third lens without departing from the teachings of the present application.

In the drawings, the thickness, size, and shape of the lens have been slightly exaggerated for convenience of explanation. In particular, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings. The figures are purely diagrammatic and not drawn to scale.

Herein, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region. The 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. Regarding the surface close to the light incident side, when the value of R is positive, the surface is judged to be convex, and when the value of R is negative, the surface is judged to be concave; the surface closer to the light exit side is determined to be concave when the R value is positive, and is determined to be convex when the R value is negative.

The invention provides an imaging system, aiming at solving the problem that a lens in the prior art is difficult to miniaturize.

Example one

As shown in fig. 1 to 30, the imaging system includes a first lens, a second lens and a third lens from the light incident side to the light emergent side. The first lens has refractive power; the second lens has negative refractive power, the surface of the second lens close to the light-in side is a convex surface, and the surface of the second lens close to the light-out side is a concave surface; the third lens has refractive power; the on-axis distance TTL from the surface of the first lens close to the light incidence side to the imaging surface of the imaging system and the half ImgH of the diagonal length of the effective pixel area on the imaging surface satisfy the following condition: TTL/ImgH < 1.6.

By distributing the refractive power of partial lenses of the imaging system and designing the surface type of the lenses, the low-order aberration of the imaging system can be effectively balanced, meanwhile, the tolerance sensitivity of the imaging system can be reduced, and the imaging quality of the imaging system is ensured while the miniaturization of the imaging system is kept. The refractive power and the surface type of the second lens are reasonably controlled, and the low-order aberration of the imaging system is favorably controlled. By controlling the ratio of the total length to the image height of the imaging system, the total size of the imaging system can be effectively reduced, and the ultra-thin characteristic and the miniaturization of the imaging system are realized.

Preferably, an on-axis distance TTL from a surface of the first lens close to the light incident side to an imaging plane of the imaging system and a half ImgH of a diagonal length of an effective pixel area on the imaging plane satisfy: 1.0< TTL/ImgH < 1.5.

In the present embodiment, the effective focal length f3 of the third lens and the radius of curvature R5 of the surface of the third lens near the light incident side satisfy: f3/R5< 1.0. The ratio of the effective focal length of the third lens to the curvature radius of the surface of the third lens close to the light incidence side is reasonably restricted, the refractive power of the imaging system can be reasonably distributed, and the third-order astigmatism of the imaging system can be controlled within a certain range, so that the imaging system has good imaging quality. Preferably 0.2< f3/R5< 0.95.

In this embodiment, an on-axis distance TTL from a surface of the first lens near the light entrance side to the imaging plane and an entrance pupil diameter EPD of the imaging system satisfy: 2.5< TTL/EPD < 3.5. The ratio of the total optical length of the imaging system to the diameter of the entrance pupil is controlled within a reasonable numerical range, the ultrathin characteristic and miniaturization of the imaging system are facilitated, the collection capacity of the imaging system for object information is kept, and the imaging quality of the imaging system is guaranteed. Preferably, 2.7< TTL/EPD < 3.3.

In the present embodiment, the height Do of the object and the minimum on-axis distance TOL of the object to the surface of the first lens on the light incident side satisfy: 0.6< Do/TOL < 1.2. The ratio of the height of the shot object to the minimum axial distance from the shot object to the surface, close to the light incidence side, of the first lens is controlled to be within a reasonable numerical range, the collection capability of the imaging system on object information is improved, and the collection range of the imaging system on the object information is ensured. Preferably, 0.8< Do/TOL < 1.1.

In the present embodiment, the maximum half field angle Semi-FOV of the imaging system satisfies: Semi-FOV > 35. By restraining half of the maximum field angle of the imaging system, the method is beneficial to obtaining a larger field range, improves the collection capacity of the imaging system on object information, and realizes the small and wide-angle imaging effect of the imaging system. Preferably, 40 ° < Semi-FOV <50 °.

In the present embodiment, the effective focal length f1 of the first lens and the effective focal length f2 of the second lens satisfy: f1/f2> -0.8. The ratio of the effective focal length of the first lens to the effective focal length of the second lens is reasonably controlled, so that the spherical aberration contribution rate of the first lens and the second lens to the imaging system is favorably controlled, and the imaging system has good imaging quality on an on-axis view field. Preferably, -0.3< f1/f2< -0.75.

In this embodiment, the combined focal length f12 of the first and second lenses and the combined focal length f23 of the second and third lenses satisfy: 0.4< f12/f23< 1.0. The ratio of the synthetic focal length of the first lens and the second lens to the synthetic focal length of the second lens and the third lens is controlled within a reasonable numerical range, so that the reasonable distribution of the refractive power of the first lens, the second lens and the third lens on the space is facilitated, and the aberration of an imaging system is further reduced. Preferably 0.6< f12/f23< 10.95.

In the present embodiment, the radius of curvature R1 of the surface of the first lens on the light incident side and the radius of curvature R2 of the surface of the first lens on the light exit side satisfy: R1/R2< 2.5. The curvature radius of the surface of the first lens close to the light inlet side and the curvature radius of the surface of the first lens close to the light outlet side are reasonably controlled, the deflection angle of marginal light rays of the imaging system can be effectively controlled, and the sensitivity of the imaging system is effectively reduced. Preferably, 0.2< R1/R2< 2.4.

In the present embodiment, the radius of curvature R3 of the surface of the second lens on the light incident side and the radius of curvature R4 of the surface of the second lens on the light exit side satisfy: l (R3-R4)/(R3+ R4) | < 0.8. The ratio of the difference and the sum of the surface curvature radius of the second lens close to the light inlet side and the surface curvature radius of the second lens close to the light outlet side is controlled within a reasonable numerical range, so that the reasonable matching of the curvature radii of the two side surfaces of the second lens is facilitated, the shape of the second lens, the refraction angle of the light beam and the contribution of the second lens to the astigmatism of the imaging system can be effectively controlled, the second lens has better processability, and the imaging system has good imaging quality. Preferably, 0.2< | (R3-R4)/(R3+ R4) | < 0.7.

In the present embodiment, the central thickness CT1 of the first lens on the optical axis of the imaging system and the central thickness CT3 of the third lens on the optical axis satisfy: 0.4< CT1/CT3< 1.2. The ratio of the central thicknesses of the first lens and the third lens is controlled within a reasonable numerical range, so that the thicknesses of the first lens and the third lens can be effectively balanced, the product yield is prevented from being influenced due to the fact that the thickness of the first lens is too thin, meanwhile, the stability of an imaging system can be improved, and the sensitivity of the imaging system is reduced. Preferably 0.6< CT1/CT3< 1.1.

In the present embodiment, the first lens and the second lens satisfy, between an air interval T12 on the optical axis of the imaging system, and a sum Σ AT of air intervals on the optical axis between any adjacent two lenses having refractive power among the first lens to the third lens: 0.3< T12/∑ AT < 0.9. The air space on the optical axis between each lens is reasonably distributed, the processing and assembling characteristics can be ensured, and the problem of interference of the front lens and the rear lens in the assembling process caused by too small space is avoided. Meanwhile, the light deflection is favorably slowed down, the field curvature of the imaging system is adjusted, the sensitivity of the imaging system is reduced, and better imaging quality is obtained. Preferably, 0.4< T12/∑ AT < 0.8.

In the present embodiment, the center thickness CT2 of the second lens on the optical axis of the imaging system, the air interval T23 of the second lens and the third lens on the optical axis, and the effective focal length f of the imaging system satisfy: (CT2+ T23)/f < 0.5. The ratio of the distance between the surface of the second lens close to the light incidence side and the surface of the third lens close to the light incidence side on the optical axis to the effective focal length is controlled within a reasonable numerical range, so that the imaging system has higher aberration correction capability and can obtain better manufacturability. Preferably, 0.1< (CT2+ T23)/f < 0.3.

In this embodiment, the on-axis distance SAG31 from the intersection point of the surface of the third lens close to the light-in side and the optical axis of the imaging system to the effective radius vertex of the surface of the third lens close to the light-in side, and the on-axis distance SAG32 from the intersection point of the surface of the third lens close to the light-out side and the optical axis to the effective radius vertex of the surface of the third lens close to the light-out side satisfy: 0.4< (SAG31+ SAG32)/SAG32< 1.0. The ratio of the sum of the rise of the two surfaces of the third lens to the rise of the surface close to the light-emitting side is controlled within a reasonable numerical range, so that the shape of the third lens is favorably controlled, the processability of the third lens is improved, the deflection angle of light of an imaging system is favorably controlled, and the imaging system has better imaging quality. Preferably, 0.5< (SAG31+ SAG32)/SAG32< 0.9.

In this embodiment, the on-axis distance SAG21 from the intersection point of the surface of the second lens close to the light-in side and the optical axis of the imaging system to the effective radius vertex of the surface of the second lens close to the light-in side, and the on-axis distance SAG22 from the intersection point of the surface of the second lens close to the light-out side and the optical axis to the effective radius vertex of the surface of the second lens close to the light-out side satisfy: (SAG21-SAG22)/(SAG21+ SAG22) < 0.7. The rise difference and the ratio of sum of two surfaces of rational control second lens are favorable to controlling the shape of second lens to make the processing nature of second lens obtain promoting, still be favorable to controlling the deflection angle of imaging system's light simultaneously, and then make imaging system have better imaging quality. Preferably, 0< (SAG21-SAG22)/(SAG21+ SAG22) < 0.5.

In the embodiment, the effective half aperture DT11 of the surface of the first lens close to the light incident side, the effective half aperture DT21 of the surface of the second lens close to the light incident side, and the effective half aperture DT31 of the surface of the third lens close to the light incident side satisfy: 0.5< (DT11+ DT21)/DT31< 1.2. The effective half aperture ratio of the sum of the effective half apertures of the surfaces of the first lens and the second lens close to the light incident side to the surface of the third lens close to the light incident side is controlled within a reasonable numerical range, so that the deflection height of marginal light of the imaging system can be effectively controlled, and the sensitivity of the imaging system is effectively reduced. Preferably, 0.6< (DT11+ DT21)/DT31< 1.1.

In this embodiment, a distance BFL from a surface of the third lens close to the light-emitting side to the imaging plane on the optical axis of the imaging system, and an on-axis distance SD from the aperture of the imaging system to the surface of the third lens close to the light-emitting side satisfy: 0.4< BFL/SD < 1.0. The ratio of the distance from the surface of the third lens close to the light-emitting side to the imaging surface on the optical axis to the distance from the diaphragm to the surface of the third lens close to the light-emitting side on the axis is controlled within a reasonable numerical range, so that the optical back focal length and the height of the lens are favorably and reasonably distributed, and the imaging system is convenient to assemble. Preferably, 0.5< BFL/SD < 0.9.

Example two

As shown in fig. 1 to 30, the imaging system includes a first lens, a second lens and a third lens from the light incident side to the light emergent side. The first lens has refractive power; the second lens has negative refractive power, the surface of the second lens close to the light-in side is a convex surface, and the surface of the second lens close to the light-out side is a concave surface; the third lens has refractive power; the on-axis distance TTL from the surface of the first lens close to the light incidence side to the imaging surface and the entrance pupil diameter EPD of the imaging system satisfy the following conditions: 2.5< TTL/EPD < 3.5.

By distributing the refractive power of partial lenses of the imaging system and designing the surface type of the lenses, the low-order aberration of the imaging system can be effectively balanced, meanwhile, the tolerance sensitivity of the imaging system can be reduced, and the imaging quality of the imaging system is ensured while the miniaturization of the imaging system is kept. The ratio of the total optical length of the imaging system to the diameter of the entrance pupil is controlled within a reasonable numerical range, the ultrathin characteristic and miniaturization of the imaging system are facilitated, the collection capacity of the imaging system for object information is kept, and the imaging quality of the imaging system is guaranteed.

Preferably, an on-axis distance TTL from a surface of the first lens close to the light entrance side to the imaging plane and an entrance pupil diameter EPD of the imaging system satisfy: 2.7< TTL/EPD < 3.3.

In the present embodiment, the effective focal length f3 of the third lens and the radius of curvature R5 of the surface of the third lens near the light incident side satisfy: f3/R5< 1.0. The ratio of the effective focal length of the third lens to the curvature radius of the surface of the third lens close to the light incidence side is reasonably constrained, the refractive power of the imaging system can be reasonably distributed, and the third-order astigmatism of the imaging system can be controlled within a certain range, so that the imaging system has good imaging quality. Preferably 0.2< f3/R5< 0.95.

In the present embodiment, the height Do of the object and the minimum on-axis distance TOL of the object to the surface of the first lens on the light incident side satisfy: 0.6< Do/TOL < 1.2. The ratio of the height of the shot object to the minimum axial distance from the shot object to the surface, close to the light incidence side, of the first lens is controlled to be within a reasonable numerical range, the collection capability of the imaging system on object information is improved, and the collection range of the imaging system on the object information is ensured. Preferably, 0.8< Do/TOL < 1.1.

In the present embodiment, the maximum half field angle Semi-FOV of the imaging system satisfies: Semi-FOV >35 deg. By restraining half of the maximum field angle of the imaging system, a larger field range is favorably obtained, the collection capacity of the imaging system for object information is improved, and the small and wide-angle imaging effect of the imaging system is realized. Preferably, 40 ° < Semi-FOV <50 °.

In the present embodiment, the effective focal length f1 of the first lens and the effective focal length f2 of the second lens satisfy: f1/f2> -0.8. The ratio of the effective focal length of the first lens to the effective focal length of the second lens is reasonably controlled, so that the spherical aberration contribution rate of the first lens and the second lens to the imaging system is favorably controlled, and the imaging system has good imaging quality on an on-axis view field. Preferably, -0.3< f1/f2< -0.75.

In the present embodiment, the combined focal length f12 of the first lens and the second lens and the combined focal length f23 of the second lens and the third lens satisfy: 0.4< f12/f23< 1.0. The ratio of the synthetic focal length of the first lens and the second lens to the synthetic focal length of the second lens and the third lens is controlled within a reasonable numerical range, so that the reasonable distribution of the refractive power of the first lens, the second lens and the third lens in space is facilitated, and the aberration of an imaging system is further reduced. Preferably 0.6< f12/f23< 10.95.

In the present embodiment, the radius of curvature R1 of the surface of the first lens on the light incident side and the radius of curvature R2 of the surface of the first lens on the light exit side satisfy: R1/R2< 2.5. The curvature radius of the surface of the first lens close to the light inlet side and the curvature radius of the surface of the first lens close to the light outlet side are reasonably controlled, the deflection angle of marginal light rays of the imaging system can be effectively controlled, and the sensitivity of the imaging system is effectively reduced. Preferably 0.2< R1/R2< 2.4.

In the present embodiment, the radius of curvature R3 of the surface of the second lens on the light incident side and the radius of curvature R4 of the surface of the second lens on the light exit side satisfy: l (R3-R4)/(R3+ R4) | < 0.8. The ratio of the difference and the sum of the surface curvature radius of the second lens close to the light inlet side and the surface curvature radius of the second lens close to the light outlet side is controlled within a reasonable numerical range, so that the reasonable matching of the curvature radii of the two side surfaces of the second lens is facilitated, the shape of the second lens, the refraction angle of the light beam and the contribution of the second lens to the astigmatism of the imaging system can be effectively controlled, the second lens has better processability, and the imaging system has good imaging quality. Preferably, 0.2< | (R3-R4)/(R3+ R4) | < 0.7.

In the present embodiment, the central thickness CT1 of the first lens on the optical axis of the imaging system and the central thickness CT3 of the third lens on the optical axis satisfy: 0.4< CT1/CT3< 1.2. The ratio of the central thicknesses of the first lens and the third lens is controlled within a reasonable numerical range, so that the thicknesses of the first lens and the third lens can be effectively balanced, the problem that the product yield is influenced due to the fact that the thickness of the first lens is too thin is avoided, meanwhile, the stability of an imaging system can be improved, and the sensitivity of the imaging system is reduced. Preferably 0.6< CT1/CT3< 1.1.

In the present embodiment, the first lens and the second lens satisfy, between an air interval T12 on the optical axis of the imaging system, and a sum Σ AT of air intervals on the optical axis between any adjacent two lenses having refractive power among the first lens to the third lens: 0.3< T12/∑ AT < 0.9. The air space on the optical axis between each lens is reasonably distributed, the processing and assembling characteristics can be ensured, and the problem of interference of the front lens and the rear lens in the assembling process caused by too small space is avoided. Meanwhile, the light deflection is favorably slowed down, the field curvature of the imaging system is adjusted, the sensitivity of the imaging system is reduced, and better imaging quality is obtained. Preferably, 0.4< T12/∑ AT < 0.8.

In the present embodiment, the center thickness CT2 of the second lens on the optical axis of the imaging system, the air interval T23 of the second lens and the third lens on the optical axis, and the effective focal length f of the imaging system satisfy: (CT2+ T23)/f < 0.5. The ratio of the distance between the surface of the second lens close to the light incidence side and the surface of the third lens close to the light incidence side on the optical axis to the effective focal length is controlled within a reasonable numerical range, so that the imaging system has higher aberration correction capability and can obtain better manufacturability. Preferably, 0.1< (CT2+ T23)/f < 0.3.

In this embodiment, the on-axis distance SAG31 from the intersection point of the surface of the third lens close to the light-in side and the optical axis of the imaging system to the effective radius vertex of the surface of the third lens close to the light-in side, and the on-axis distance SAG32 from the intersection point of the surface of the third lens close to the light-out side and the optical axis to the effective radius vertex of the surface of the third lens close to the light-out side satisfy: 0.4< (SAG31+ SAG32)/SAG32< 1.0. The ratio of the sum of the rise of the two surfaces of the third lens to the rise of the surface close to the light-emitting side is controlled within a reasonable numerical range, so that the shape of the third lens is favorably controlled, the processability of the third lens is improved, the deflection angle of light of an imaging system is favorably controlled, and the imaging system has better imaging quality. Preferably, 0.5< (SAG31+ SAG32)/SAG32< 0.9.

In this embodiment, the on-axis distance SAG21 from the intersection point of the surface of the second lens close to the light-in side and the optical axis of the imaging system to the effective radius vertex of the surface of the second lens close to the light-in side, and the on-axis distance SAG22 from the intersection point of the surface of the second lens close to the light-out side and the optical axis to the effective radius vertex of the surface of the second lens close to the light-out side satisfy: (SAG21-SAG22)/(SAG21+ SAG22) < 0.7. The rise difference and the ratio of sum of two surfaces of rational control second lens are favorable to controlling the shape of second lens to make the processing nature of second lens obtain promoting, still be favorable to controlling the deflection angle of imaging system's light simultaneously, and then make imaging system have better imaging quality. Preferably, 0< (SAG21-SAG22)/(SAG21+ SAG22) < 0.5.

In the embodiment, the effective half aperture DT11 of the surface of the first lens close to the light incident side, the effective half aperture DT21 of the surface of the second lens close to the light incident side, and the effective half aperture DT31 of the surface of the third lens close to the light incident side satisfy: 0.5< (DT11+ DT21)/DT31< 1.2. The effective half aperture ratio of the sum of the effective half apertures of the surfaces of the first lens and the second lens close to the light incident side to the surface of the third lens close to the light incident side is controlled within a reasonable numerical range, so that the deflection height of marginal light of the imaging system can be effectively controlled, and the sensitivity of the imaging system is effectively reduced. Preferably, 0.6< (DT11+ DT21)/DT31< 1.1.

In this embodiment, a distance BFL from a surface of the third lens close to the light exit side to the imaging plane on the optical axis of the imaging system, and an on-axis distance SD from the aperture of the imaging system to the surface of the third lens close to the light exit side satisfy: 0.4< BFL/SD < 1.0. The ratio of the distance from the surface of the third lens close to the light-emitting side to the imaging surface on the optical axis to the distance from the diaphragm to the surface of the third lens close to the light-emitting side on the axis is controlled within a reasonable numerical range, so that the optical back focal length and the height of the lens are favorably and reasonably distributed, and the imaging system is convenient to assemble. Preferably, 0.5< BFL/SD < 0.9.

Optionally, the above-described imaging system may further include a filter for correcting color deviation and/or a protective glass for protecting the photosensitive element located on the imaging surface.

The imaging system in the present application may employ multiple lenses, such as the three lenses described above. By reasonably distributing the refractive power, the surface shape, the center thickness of each lens, the on-axis distance between each lens and the like, the imaging quality of the imaging system can be effectively improved, the sensitivity of the imaging system is reduced, and the machinability of the imaging system is improved, so that the imaging system is more beneficial to production and processing and is applicable to portable electronic equipment such as smart phones.

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 a better curvature radius characteristic, 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 three lenses are exemplified in the embodiment, the imaging system is not limited to including three lenses. The imaging system may also include other numbers of lenses, as desired.

Examples of specific surface types, parameters that can be applied 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 configuration diagram of an imaging system of example one.

As shown in fig. 1, the imaging system, in order from an object side to an image side, comprises: stop STO, first lens E1, second lens E2, third lens E3, filter E4, and image plane S9.

The first lens E1 has positive refractive power, and the surface S1 of the first lens close to the light-in side is convex, and the surface S2 of the first lens close to the light-out side is concave. The second lens element E2 has negative refractive power, and has a convex surface S3 on the light incident side and a concave surface S4 on the light exit side. The third lens E3 has positive refractive power, and the surface S5 of the third lens close to the light-in side is convex, and the surface S6 of the third lens close to the light-out side is concave. The filter E4 has a surface S7 close to the light entrance side and a surface S8 close to the light exit side. The light from the object passes through the respective surfaces S1 to S8 in order and is finally imaged on the imaging surface S9.

In this example, the image height ImgH of the imaging system is 1.72 mm. The total length TTL of the imaging system was 2.17 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, and the focal length are all millimeters (mm).

TABLE 1

In the first example, a surface of any one of the first lens E1 to the third lens E3 close to the light incident side and a surface close to the light emergent side are both aspheric surfaces, and the surface shape of each aspheric surface lens can be defined by, but is not limited to, the following aspheric surface formula:

wherein x is the rise of the distance from the aspheric surface vertex to the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 1 above); k is a conic coefficient; ai is the correction coefficient of the i-th order of the aspherical surface. Table 2 below gives the high-order coefficient A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28, A30 that can be used for each of the aspherical mirrors S1-S6 in example one.

Flour mark

A4

A6

A8

A10

A12

A14

A16

S1

-3.2285E+00

4.8723E+02

-4.5202E+04

2.8210E+06

-1.2331E+08

3.8599E+09

-8.7609E+10

S2

-2.2148E+00

3.0496E+02

-2.2770E+04

1.0653E+06

-3.3906E+07

7.6766E+08

-1.2648E+10

S3

-1.7828E+00

-1.0686E+02

8.6249E+03

-3.6166E+05

1.0058E+07

-1.9461E+08

2.6725E+09

S4

-5.3242E+00

8.1098E+00

1.4875E+03

-4.3009E+04

6.9662E+05

-7.5274E+06

5.7125E+07

S5

-3.4131E+00

1.4698E+01

-7.5209E+01

3.3547E+02

-1.2274E+03

3.6236E+03

-8.3828E+03

S6

-3.6143E-01

-7.8792E+00

6.8453E+01

-3.5566E+02

1.2560E+03

-3.1264E+03

5.5934E+03

Flour mark

A18

A20

A22

A24

A26

A28

A30

S1

1.4488E+12

-1.7402E+13

1.4984E+14

-8.9962E+14

3.5708E+15

-8.4123E+15

8.8986E+15

S2

1.5288E+11

-1.3509E+12

8.5965E+12

-3.8225E+13

1.1234E+14

-1.9548E+14

1.5205E+14

S3

-2.6319E+10

1.8605E+11

-9.3455E+11

3.2508E+12

-7.4336E+12

1.0038E+13

-6.0583E+12

S4

-3.1081E+08

1.2183E+09

-3.4104E+09

6.6486E+09

-8.5715E+09

6.5666E+09

-2.2627E+09

S5

1.4663E+04

-1.8800E+04

1.7198E+04

-1.0862E+04

4.4886E+03

-1.0908E+03

1.1816E+02

S6

-7.2641E+03

6.8484E+03

-4.6342E+03

2.1909E+03

-6.8623E+02

1.2781E+02

-1.0703E+01

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 an astigmatism curve for the imaging system of example one, representing meridional and sagittal image planes. 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. Fig. 6 shows a schematic configuration diagram of an imaging system of example two.

As shown in fig. 6, the imaging system comprises, in order from an object side to an image side: stop STO, first lens E1, second lens E2, third lens E3, filter E4, and image plane S9.

The first lens E1 has positive refractive power, and the surface S1 of the first lens close to the light-in side is convex, and the surface S2 of the first lens close to the light-out side is concave. The second lens element E2 has negative refractive power, and has a convex surface S3 on the light incident side and a concave surface S4 on the light exit side. The third lens E3 has positive refractive power, and the surface S5 of the third lens close to the light-in side is convex, and the surface S6 of the third lens close to the light-out side is concave. The filter E4 has a surface S7 close to the light entrance side and a surface S8 close to the light exit side. The light from the object passes through the respective surfaces S1 to S8 in order and is finally imaged on the imaging surface S9.

In this example, the image height ImgH of the imaging system is 1.72 mm. The total length of the imaging system, TTL, was 2.13 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, thickness/distance, and focal length 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

S1

-7.4746E-01

5.4483E+01

-2.1601E+03

5.0126E+04

-7.1246E+05

6.2229E+06

S2

-5.4814E-01

4.0593E+01

-1.4594E+03

2.8282E+04

-3.2081E+05

2.1254E+06

S3

-2.1938E+00

2.5295E+00

1.0057E+03

-3.2695E+04

5.5029E+05

-5.7065E+06

S4

-5.0521E+00

6.2730E+01

-6.8720E+02

5.6740E+03

-3.3190E+04

1.3354E+05

S5

-3.3022E+00

1.8886E+01

-1.1036E+02

4.4652E+02

-1.2050E+03

2.1721E+03

S6

-1.0169E+00

2.9856E+00

-1.3357E+01

4.0187E+01

-7.6453E+01

9.3348E+01

Flour mark

A16

A18

A20

A22

A24

S1

-3.2331E+07

9.0902E+07

-1.0570E+08

0.0000E+00

0.0000E+00

S2

-7.8106E+06

1.3528E+07

-6.3375E+06

0.0000E+00

0.0000E+00

S3

3.7651E+07

-1.5505E+08

3.6919E+08

-4.1357E+08

8.7458E+07

S4

-3.5981E+05

6.1916E+05

-6.1471E+05

2.6788E+05

0.0000E+00

S5

-2.6150E+03

2.0749E+03

-1.0422E+03

3.0067E+02

-3.7995E+01

S6

-7.3162E+01

3.5525E+01

-9.6912E+00

1.1306E+00

0.0000E+00

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 configuration diagram of an imaging system of example three.

As shown in fig. 11, the imaging system, in order from an object side to an image side, comprises: stop STO, first lens E1, second lens E2, third lens E3, filter E4, and image plane S9.

The first lens E1 has positive refractive power, and the surface S1 of the first lens close to the light-in side is convex, and the surface S2 of the first lens close to the light-out side is concave. The second lens element E2 has negative refractive power, and has a convex surface S3 on the light incident side and a concave surface S4 on the light exit side. The third lens E3 has positive refractive power, and the surface S5 of the third lens close to the light-in side is convex, and the surface S6 of the third lens close to the light-out side is concave. The filter E4 has a surface S7 close to the light entrance side and a surface S8 close to the light exit side. The light from the object passes through the respective surfaces S1 to S8 in order and is finally imaged on the imaging surface S9.

In this example, the image height ImgH of the imaging system is 1.72 mm. The total length TTL of the imaging system is 2.16 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, and focal length 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 configuration diagram of an imaging system of example four.

As shown in fig. 16, the imaging system, in order from an object side to an image side, comprises: stop STO, first lens E1, second lens E2, third lens E3, filter E4, and image plane S9.

The first lens E1 has positive refractive power, the surface S1 of the first lens close to the light-in side is convex, and the surface S2 of the first lens close to the light-out side is concave. The second lens element E2 has negative refractive power, and has a convex surface S3 on the light incident side and a concave surface S4 on the light emergent side. The third lens E3 has positive refractive power, the surface S5 of the third lens close to the light-in side is convex, and the surface S6 of the third lens close to the light-out side is concave. The filter E4 has a surface S7 close to the light entrance side and a surface S8 close to the light exit side. The light from the object passes through the respective surfaces S1 to S8 in order and is finally imaged on the imaging surface S9.

In this example, the image height ImgH of the imaging system is 1.72 mm. The total length TTL of the imaging system is 2.24 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, thickness/distance, and focal length 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

-9.5073E-01

6.0257E+01

-2.1220E+03

4.3422E+04

-5.4630E+05

4.2707E+06

-2.0185E+07

S2

-2.7854E-01

1.2260E+01

-4.0963E+02

6.4539E+03

-5.7724E+04

2.9192E+05

-7.7327E+05

S3

-2.4821E+00

2.5441E+01

-1.7578E+02

-8.5261E+03

4.0266E+05

-9.0582E+06

1.2922E+08

S4

-4.1572E+00

2.6883E+01

7.6680E+01

-7.1358E+03

1.3365E+05

-1.5039E+06

1.1513E+07

S5

-2.1834E+00

6.0285E+00

-2.5724E+01

1.3807E+02

-8.3954E+02

4.0014E+03

-1.3135E+04

S6

-9.8282E-02

-4.9009E+00

3.4372E+01

-1.7671E+02

6.7178E+02

-1.8716E+03

3.8195E+03

Flour mark

A18

A20

A22

A24

A26

A28

A30

S1

5.2688E+07

-5.8171E+07

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

S2

7.8156E+05

1.8475E+05

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

S3

-1.2607E+09

8.6437E+09

-4.1761E+10

1.3954E+11

-3.0744E+11

4.0226E+11

-2.3696E+11

S4

-6.2322E+07

2.4120E+08

-6.6323E+08

1.2648E+09

-1.5891E+09

1.1822E+09

-3.9424E+08

S5

2.9405E+04

-4.5222E+04

4.7762E+04

-3.4066E+04

1.5691E+04

-4.2178E+03

5.0294E+02

S6

-5.7055E+03

6.1993E+03

-4.8252E+03

2.6125E+03

-9.3175E+02

1.9634E+02

-1.8479E+01

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 configuration diagram of an imaging system of example five.

As shown in fig. 21, the imaging system, in order from an object side to an image side, comprises: stop STO, first lens E1, second lens E2, third lens E3, filter E4, and image plane S9.

The first lens E1 has positive refractive power, the surface S1 of the first lens close to the light-in side is convex, and the surface S2 of the first lens close to the light-out side is concave. The second lens element E2 has negative refractive power, and has a convex surface S3 on the light incident side and a concave surface S4 on the light exit side. The third lens E3 has positive refractive power, and the surface S5 of the third lens close to the light-in side is convex, and the surface S6 of the third lens close to the light-out side is concave. The filter E4 has a surface S7 close to the light entrance side and a surface S8 close to the light exit side. The light from the object passes through the respective surfaces S1 to S8 in order and is finally imaged on the imaging surface S9.

In this example, the image height ImgH of the imaging system is 1.72 mm. The total length TTL of the imaging system is 2.29 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, and focal length 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

-9.5251E-01

5.4273E+01

-1.7669E+03

3.3347E+04

-3.8645E+05

2.7802E+06

-1.2087E+07

S2

-2.5151E-01

6.4506E+00

-2.2168E+02

3.2323E+03

-2.6359E+04

1.2089E+05

-2.9062E+05

S3

-1.6917E+00

1.6672E+00

1.5182E+02

-2.5998E+03

2.0498E+04

-1.1006E+05

1.2117E+06

S4

-3.2265E+00

-6.6530E+00

7.5404E+02

-1.5524E+04

1.9436E+05

-1.6760E+06

1.0357E+07

S5

-1.8471E+00

-1.4113E+00

8.3747E+01

-9.0988E+02

5.8760E+03

-2.5777E+04

8.0246E+04

S6

-8.8152E-02

-2.3480E+00

-9.2702E-01

7.8361E+01

-5.1901E+02

1.9678E+03

-5.0006E+03

Flour mark

A18

A20

A22

A24

A26

A28

A30

S1

2.9020E+07

-2.9476E+07

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

S2

2.6851E+05

5.4366E+04

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

S3

-1.9152E+07

1.9375E+08

-1.2047E+09

4.7196E+09

-1.1447E+10

1.5763E+10

-9.4513E+09

S4

-4.6554E+07

1.5238E+08

-3.5904E+08

5.9245E+08

-6.4903E+08

4.2354E+08

-1.2449E+08

S5

-1.8005E+05

2.9124E+05

-3.3547E+05

2.6764E+05

-1.4026E+05

4.3366E+04

-5.9889E+03

S6

8.9432E+03

-1.1430E+04

1.0396E+04

-6.5731E+03

2.7453E+03

-6.8046E+02

7.5729E+01

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 an astigmatism curve for the imaging system of example five, representing meridional and sagittal image planes 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 configuration diagram of an imaging system of example six.

As shown in fig. 26, the imaging system, in order from an object side to an image side, comprises: stop STO, first lens E1, second lens E2, third lens E3, filter E4, and image plane S9.

The first lens E1 has positive refractive power, and the surface S1 of the first lens close to the light-in side is convex, and the surface S2 of the first lens close to the light-out side is concave. The second lens element E2 has negative refractive power, and has a convex surface S3 on the light incident side and a concave surface S4 on the light exit side. The third lens E3 has positive refractive power, and the surface S5 of the third lens close to the light-in side is convex, and the surface S6 of the third lens close to the light-out side is concave. The filter E4 has a surface S7 close to the light entrance side and a surface S8 close to the light exit side. The light from the object passes through the respective surfaces S1 to S8 in order and is finally imaged on the imaging surface S9.

In this example, the image height ImgH of the imaging system is 1.72 mm. The total length TTL of the imaging system is 2.38 mm.

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, and focal length 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 \ example	1	2	3	4	5	6
							TTL/ImgH	1.26	1.24	1.25	1.30	1.33	1.39
f/f3	0.85	0.69	0.71	0.76	0.82	0.85
							f3/R5	0.89	0.26	0.27	0.28	0.29	0.28
TTL/EPD	3.17	3.04	3.05	2.88	2.80	2.75
							Do/TOL	0.99	1.01	0.99	0.95	0.93	0.88
Semi-FOV	44.6	45.3	44.8	43.7	43.0	41.4
							f1/f2	-0.69	-0.48	-0.49	-0.54	-0.59	-0.64
f12/f23	0.79	0.65	0.67	0.76	0.88	0.84
							R1/R2	2.37	0.44	0.44	0.39	0.37	0.35
|(R3-R4)/(R3+R4)|	0.65	0.40	0.40	0.36	0.32	0.33
							CT1/CT3	0.66	0.66	0.67	0.76	0.83	0.98
T12/∑AT	0.58	0.54	0.55	0.61	0.66	0.69
							(CT2+T23)/f	0.24	0.25	0.25	0.22	0.21	0.19
(SAG31+SAG32)/SAG32	0.61	0.73	0.73	0.70	0.82	0.68
							(SAG21-SAG22)/(SAG21+SAG22)	0.06	0.43	0.43	0.25	0.40	0.28
(DT11+DT21)/DT31	0.70	0.74	0.76	0.86	0.97	1.06
							BFL/SD	0.63	0.59	0.61	0.67	0.71	0.78

Watch 13

Table 14 gives effective focal lengths f1 to f3 of the respective lenses of the imaging systems of example one to example six.

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 exemplary 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 other sequences 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 (10)

1. An imaging system, comprising from a light-in side to a light-out side:

a first lens having refractive power;

the surface of the second lens close to the light-in side is a convex surface, and the surface of the second lens close to the light-out side is a concave surface;

a third lens having refractive power;

the axial distance TTL from the surface of the first lens close to the light incidence side to the imaging surface of the imaging system and the half ImgH of the diagonal length of the effective pixel area on the imaging surface satisfy the following condition: TTL/ImgH < 1.6.

2. The imaging system of claim 1, wherein an effective focal length f3 of the third lens and a radius of curvature R5 of a surface of the third lens near the light entrance side satisfy: f3/R5< 1.0.

3. The imaging system of claim 1, wherein an on-axis distance TTL between a surface of the first lens near the light entrance side and the imaging plane and an entrance pupil diameter EPD of the imaging system satisfy: 2.5< TTL/EPD < 3.5.

4. The imaging system of claim 1, wherein a height Do of the subject and a minimum on-axis distance TOL of the subject from a surface of the first lens near the light-incident side satisfy: 0.6< Do/TOL < 1.2.

5. The imaging system of claim 1, wherein the maximum half field angle Semi-FOV of the imaging system satisfies: Semi-FOV > 35.

6. The imaging system of claim 1, wherein an effective focal length f1 of the first lens and an effective focal length f2 of the second lens satisfy: f1/f2> -0.8.

7. The imaging system of claim 1, wherein a combined focal length f12 of the first and second lenses and a combined focal length f23 of the second and third lenses satisfy: 0.4< f12/f23< 1.0.

8. The imaging system of claim 1, wherein a radius of curvature R1 of a surface of the first lens near the light-in side and a radius of curvature R2 of a surface of the first lens near the light-out side satisfy: R1/R2< 2.5.

9. The imaging system of claim 1, wherein a radius of curvature R3 of a surface of the second lens near the light-in side and a radius of curvature R4 of a surface of the second lens near the light-out side satisfy:

|(R3-R4)/(R3+R4)|<0.8。

10. an imaging system, comprising, from a light-in side to a light-out side:

a first lens having refractive power;

the surface of the second lens close to the light-in side is a convex surface, and the surface of the second lens close to the light-out side is a concave surface;

a third lens having refractive power;

the axial distance TTL from the surface of the first lens close to the light incidence side to the imaging surface of the imaging system and the entrance pupil diameter EPD of the imaging system satisfy the following conditions: 2.5< TTL/EPD < 3.5.

Images