An imaging system

Abstract

The present invention discloses an imaging system, which sequentially includes, from the object side to the image side along the optical axis: a first lens having a focal power; a second lens having a negative focal power; a third lens having a positive focal power, with its object side being convex; a fourth lens having a positive focal power, with its object side being convex and its image side being convex; a fifth lens having a negative focal power; wherein, the central thickness CT4 of the fourth lens and the effective focal length f of the imaging system satisfy: 0.5 < CT4 / f < 0.9. When the above-mentioned focal power and surface type conditions are satisfied, it is beneficial to the reasonable distribution of the focal power of the imaging system and is conducive to the imaging system to balance and correct various aberrations; when the above-mentioned lens central thickness and effective focal length conditions are satisfied, the volume ratio of the fourth lens in the optical system can be controlled, which is beneficial to the miniaturization of the volume of the imaging system.

Description

Technical Field

[0001] The invention belongs to the field of optical imaging, and in particular relates to an imaging system comprising five lenses. Background Art

[0002] In recent years, ultra-wide-angle imaging systems of various smart devices have become a new hot spot. Ultra-wide-angle imaging systems can achieve imaging effects that are close to fisheyes. General fisheye imaging systems are difficult to miniaturize, which will affect the thickness and weight of smart devices. This patent aims to overcome the pain point of the large size of the above-mentioned fisheye lenses. This application combines the characteristics of the fisheye imaging effect of the imaging system and proposes a small-volume fisheye imaging system. It has high imaging quality and a small system volume. This small-volume fisheye imaging system has a huge application space. Summary of the invention

[0003] The present invention aims to provide a small-volume imaging system, which has high imaging quality and small system volume. The small-volume fisheye imaging system has a wide range of applications.

[0004] The present application provides an imaging system, which includes, in order from the object side to the image side along the optical axis:

[0005] a first lens having optical power;

[0006] a second lens having negative optical power;

[0007] a third lens having positive refractive power and a convex object side surface;

[0008] a fourth lens element having positive refractive power, with an object side convex surface and an image side convex surface;

[0009] a fifth lens having negative optical power;

[0010] The center thickness CT4 of the fourth lens and the effective focal length f of the imaging system satisfy: 0.5 <CT4 / f<0.9。

[0011] According to one embodiment of the present application, half of the maximum field of view angle Semi-FOV of the imaging system satisfies: tan(Semi-FOV)>3.7.

[0012] According to one embodiment of the present application, the dispersion coefficient Vd2 of the second lens, the dispersion coefficient Vd3 of the third lens, and the dispersion coefficient Vd4 of the fourth lens satisfy: (Vd2-Vd3+Vd4) / 3<31.

[0013] According to one embodiment of the present application, the effective focal length f2 of the second lens, the effective focal length f5 of the fifth lens, and the effective focal length f of the imaging system satisfy: -8<(f2+f5) / f<-1.5.

[0014] According to one embodiment of the present application, the effective focal length f3 of the third lens, the effective focal length f4 of the fourth lens, and the effective focal length f of the imaging system satisfy: 2<(f3+f4) / f<4.

[0015] According to one embodiment of the present application, the maximum radius SD of the aperture stop and half the diagonal length of the effective pixel area on the imaging plane ImgH satisfy: SD / ImgH<0.25.

[0016] According to one embodiment of the present application, the effective focal length f of the imaging system and the entrance pupil diameter EPD of the imaging system satisfy: 2.1 <f / EPD<2.4。

[0017] According to one embodiment of the present application, the distance TTL from the object side of the first lens to the image plane on the optical axis, the center thickness CT3 of the third lens, the center thickness CT4 of the fourth lens, and the distance T34 from the image side of the third lens to the object side of the fourth lens on the optical axis of the imaging system satisfy: 2.3 <TTL / (CT3+T34+CT4)<3.3。

[0018] According to one embodiment of the present application, the distance TD from the object side of the first lens to the image side of the fifth lens on the optical axis and half of the diagonal length of the effective pixel area on the imaging surface ImgH satisfy: 2.0 <TD / ImgH<2.3。

[0019] According to one embodiment of the present application, the entrance pupil diameter EPD of the imaging system, half the diagonal length of the effective pixel area on the imaging surface ImgH, and the effective half-aperture DT52 of the image side of the fifth lens satisfy the following conditions: 0.15 <EPD / (ImgH+DT52)<0.3。

[0020] The present application also provides an imaging system, which includes, in order from the object side to the image side along the optical axis:

[0021] a first lens having optical power;

[0022] a second lens having negative optical power;

[0023] a third lens having positive refractive power and a convex object side surface;

[0024] a fourth lens element having positive refractive power, with an object side convex surface and an image side convex surface;

[0025] a fifth lens having negative optical power;

[0026] Among them, the effective focal length f of the imaging system and the entrance pupil diameter EPD of the imaging system satisfy: 2.1 <f / EPD<2.4。

[0027] According to one embodiment of the present application, the center thickness CT4 of the fourth lens element and the effective focal length f of the imaging system satisfy the following conditions: 0.5 <CT4 / f<0.9。

[0028] According to one embodiment of the present application, half of the maximum field of view angle Semi-FOV of the imaging system satisfies: tan(Semi-FOV)>3.7.

[0029] According to one embodiment of the present application, the dispersion coefficient Vd2 of the second lens, the dispersion coefficient Vd3 of the third lens, and the dispersion coefficient Vd4 of the fourth lens satisfy: (Vd2-Vd3+Vd4) / 3<31.

[0030] According to one embodiment of the present application, the effective focal length f2 of the second lens, the effective focal length f5 of the fifth lens, and the effective focal length f of the imaging system satisfy: -8<(f2+f5) / f<-1.5.

[0031] According to one embodiment of the present application, the effective focal length f3 of the third lens, the effective focal length f4 of the fourth lens, and the effective focal length f of the imaging system satisfy: 2<(f3+f4) / f<4.

[0032] According to one embodiment of the present application, the maximum radius SD of the aperture stop and half the diagonal length of the effective pixel area on the imaging plane ImgH satisfy: SD / ImgH<0.25.

[0033] According to one embodiment of the present application, the distance TTL from the object side of the first lens to the image plane on the optical axis, the center thickness CT3 of the third lens, the center thickness CT4 of the fourth lens, and the distance T34 from the image side of the third lens to the object side of the fourth lens on the optical axis of the imaging system satisfy: 2.3 <TTL / (CT3+T34+CT4)<3.3。

[0034] According to one embodiment of the present application, the distance TD from the object side of the first lens to the image side of the fifth lens on the optical axis and half of the diagonal length of the effective pixel area on the imaging surface ImgH satisfy: 2.0 <TD / ImgH<2.3。

[0035] According to one embodiment of the present application, the entrance pupil diameter EPD of the imaging system, half the diagonal length of the effective pixel area on the imaging surface ImgH, and the effective half-aperture DT52 of the image side of the fifth lens satisfy the following conditions: 0.15 <EPD / (ImgH+DT52)<0.3。

[0036] Beneficial effects of the present invention:

[0037] The imaging system provided by the present invention includes multiple lenses, such as the first lens to the fifth lens. When the above-mentioned optical power and surface shape conditions are met, it is conducive to the reasonable distribution of the optical power of the imaging system, and it is easy for the imaging system to balance and correct various aberrations; when the above-mentioned lens center thickness and effective focal length conditions are met, the volume proportion of the fourth lens in the optical system can be controlled, which is conducive to realizing the miniaturization of the imaging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 Schematic diagram of the lens group structure of the imaging system embodiment 1 of the present invention;

[0040] Figure 2a to Figure 2c They are respectively a distortion curve, an axial chromatic aberration curve and an astigmatism curve of the imaging system embodiment 1 of the present invention;

[0041] Figure 3 Schematic diagram of the lens group structure of the imaging system embodiment 2 of the present invention;

[0042] Figures 4a to 4c They are respectively a distortion curve, an axial chromatic aberration curve and an astigmatism curve of the imaging system embodiment 2 of the present invention;

[0043] Figure 5 Schematic diagram of the lens group structure of the imaging system embodiment 3 of the present invention;

[0044] Figures 6a to 6c They are respectively a distortion curve, an axial chromatic aberration curve and an astigmatism curve of the imaging system embodiment 3 of the present invention;

[0045] Figure 7 Schematic diagram of the lens group structure of the imaging system embodiment 4 of the present invention;

[0046] Figures 8a to 8c They are respectively a distortion curve, an axial chromatic aberration curve and an astigmatism curve of the imaging system embodiment 4 of the present invention;

[0047] Fig. 9 Schematic diagram of the lens group structure of the imaging system embodiment 5 of the present invention;

[0048] Figures 10a to 10c They are respectively a distortion curve, an axial chromatic aberration curve and an astigmatism curve of an imaging system embodiment 5 of the present invention;

[0049] Fig.11Schematic diagram of the structure of the lens group of the imaging system embodiment 6 of the present invention;

[0050] Figures 12a to 12c They are respectively the distortion curve, the axial chromatic aberration curve and the astigmatism curve of the imaging system embodiment 6 of the present invention. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0052] It should be noted that in this specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0053] It should also be understood that the terms "comprises", "including", "having", "includes" and / or "comprising", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0054] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0055] In the description of the present invention, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface 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 position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side of the lens, and the surface of each lens closest to the imaging plane is called the image side of the lens.

[0056] Unless otherwise defined, all terms (including 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. It should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and will not be interpreted in an idealized or overly formal manner unless expressly so defined herein.

[0057] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other. The features, principles and other aspects of the present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0058] Exemplary Embodiment

[0059] The imaging system of the exemplary embodiment of the present invention includes five lenses, which are sequentially arranged from the object side to the image side along the optical axis: a first lens, a second lens, a third lens, a fourth lens, and a fifth lens. Among them, each lens is independent of each other, and there is an air gap between each lens on the optical axis.

[0060] In the present exemplary embodiment, a kind of imaging system, characterized in that it sequentially includes along the optical axis from the object side to the image side: a first lens with a focal power; a second lens with a negative focal power; a third lens with a positive focal power, the object side of which is convex; a fourth lens with a positive focal power, the object side of which is convex and the image side of which is convex; a fifth lens with a negative focal power; when the above-mentioned focal power and surface type conditions are met, it is beneficial to the reasonable distribution of the focal power of the imaging system and is conducive to the imaging system to balance and correct various aberrations.

[0061] In the present exemplary embodiment, the central thickness CT4 of the fourth lens and the effective focal length f of the imaging system satisfy: 0.5 < CT4 / f < 0.9. When the above-mentioned lens central thickness and effective focal length conditions are met, the volume ratio of the fourth lens in the optical system can be controlled, which is beneficial to the miniaturization of the volume of the imaging system. More specifically, in the present exemplary embodiment, the central thickness CT4 of the fourth lens and the effective focal length f of the imaging system satisfy: 0.5 < CT4 / f < 0.87.

[0062] In the present exemplary embodiment, half of the maximum field of view angle of the imaging system Semi-FOV satisfies: tan(Semi-FOV) > 3.7. When the above-mentioned field of view angle conditions are met, it is beneficial to achieve the optical performance of a large field of view angle of the imaging system to obtain the imaging effect of a fish-eye lens. More specifically, half of the maximum field of view angle of the imaging system Semi-FOV satisfies: tan(Semi-FOV) > 3.72.

[0063] In this exemplary embodiment, the Abbe number Vd2 of the second lens, the Abbe number Vd3 of the third lens, and the Abbe number Vd4 of the fourth lens satisfy: (Vd2 - Vd3 + Vd4) / 3 < 31. When the Abbe number conditions of each lens are satisfied as above, the optical path difference of polychromatic light in each lens is reasonably allocated, which is beneficial to correcting the lateral chromatic aberration of the imaging system. More specifically, the Abbe number Vd2 of the second lens, the Abbe number Vd3 of the third lens, and the Abbe number Vd4 of the fourth lens satisfy: (Vd2 - Vd3 + Vd4) / 3 < 30.7.

[0064] In this exemplary embodiment, the effective focal length f2 of the second lens, the effective focal length f5 of the fifth lens, and the effective focal length f of the imaging system satisfy: -8 < (f2 + f5) / f < -1.5. When the above effective focal length conditions are satisfied, the effective focal lengths of the second lens and the fifth lens are restricted, which is beneficial to reducing the volumes of the second lens and the fifth lens and realizing the miniaturization of the volume of the imaging system. More specifically, the effective focal length f2 of the second lens, the effective focal length f5 of the fifth lens, and the effective focal length f of the imaging system satisfy: -7.2 < (f2 + f5) / f < -1.94.

[0065] In this exemplary embodiment, the effective focal length f3 of the third lens, the effective focal length f4 of the fourth lens, and the effective focal length f of the imaging system satisfy: 2 < (f3 + f4) / f < 4. When the above effective focal length conditions are satisfied, the effective focal lengths of the third lens and the fourth lens are restricted, which is beneficial to reducing the volumes of the third lens and the fourth lens and realizing the miniaturization of the volume of the imaging system. More specifically, the effective focal length f3 of the third lens, the effective focal length f4 of the fourth lens, and the effective focal length f of the imaging system satisfy: 2.45 < (f3 + f4) / f < 3.82.

[0066] In this exemplary embodiment, the maximum radius SD of the aperture stop and half of the diagonal length ImgH of the effective pixel region on the imaging plane satisfy: SD / ImgH < 0.25. When the above conditions are satisfied, the aperture of the stop is controlled, reducing the risk of ghost images. More specifically, the maximum radius SD of the aperture stop and half of the diagonal length ImgH of the effective pixel region on the imaging plane satisfy: SD / ImgH ≤ 0.24.

[0067] In this exemplary embodiment, the effective focal length f of the imaging system and the entrance pupil diameter EPD of the imaging system satisfy: 2.1 < f / EPD < 2.4. When the above conditions are satisfied, the aperture of the imaging system is restricted, which is beneficial to realizing the miniaturization of the aperture of the imaging system. More specifically, the effective focal length f of the imaging system and the entrance pupil diameter EPD of the imaging system satisfy: 2.15 < f / EPD < 2.38.

[0068] In the present exemplary embodiment, the distance TTL from the object side surface of the first lens to the image plane on the optical axis, the central thickness CT3 of the third lens, the central thickness CT4 of the fourth lens, and the distance T34 from the image side surface of the third lens to the object side surface of the fourth lens on the optical axis satisfy: 2.3 < TTL / (CT3 + T34 + CT4) < 3.3. When the above conditions are satisfied, the central thicknesses of the third lens and the fourth lens are reasonably allocated, which is beneficial to correcting the axial aberration of the imaging system and also meets the processing and production requirements. More specifically, the distance TTL from the object side surface of the first lens to the image plane on the optical axis, the central thickness CT3 of the third lens, the central thickness CT4 of the fourth lens, and the distance T34 from the image side surface of the third lens to the object side surface of the fourth lens on the optical axis satisfy: 2.33 < TTL / (CT3 + T34 + CT4) < 3.3.

[0069] In the present exemplary embodiment, the distance TD from the object side surface of the first lens to the image side surface of the fifth lens on the optical axis and half of the diagonal length ImgH of the effective pixel region on the imaging plane satisfy: 2.05 < TD / ImgH < 2.25.

[0070] In the present exemplary embodiment, the entrance pupil diameter EPD of the imaging system, half of the diagonal length ImgH of the effective pixel region on the imaging plane, and the effective semi-aperture DT52 of the image side surface of the fifth lens satisfy: 0.15 < EPD / (ImgH + DT52) < 0.3. When the above conditions are satisfied, the overall optical length of the imaging system is limited, which is beneficial to realizing the miniaturization of the overall length of the imaging system. More specifically, the entrance pupil diameter EPD of the imaging system, half of the diagonal length ImgH of the effective pixel region on the imaging plane, and the effective semi-aperture DT52 of the image side surface of the fifth lens satisfy: 0.17 < EPD / (ImgH + DT52) < 0.29.

[0071] In the present exemplary embodiment, the curvature radius R7 of the object side surface of the fourth lens and the curvature radius R8 of the image side surface of the fourth lens satisfy: 0.6 < (R7 + R8) / (R7 - R8) < 0.8. When the above conditions are satisfied, the shapes of the object side surface and the image side surface of the fourth lens are limited, which is beneficial to balancing the monochromatic aberration of the imaging system. More specifically, the curvature radius R7 of the object side surface of the fourth lens and the curvature radius R8 of the image side surface of the fourth lens satisfy: 0.61 < (R7 + R8) / (R7 - R8) < 0.78.

[0072] In the present exemplary embodiment, the object side surface and the image side surface of any one of the first lens E1 to the fifth lens E5 are aspherical surfaces, and the surface shape x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0073]

[0074] Wherein, x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c=1 / R (i.e., the paraxial curvature c is the reciprocal of the curvature radius R in Table 1); k is the cone coefficient; Ai is the correction coefficient of the i-th order aspheric surface.

[0075] In this exemplary embodiment, the imaging system may further include an aperture. The aperture may be disposed at an appropriate position as required, for example, the aperture may be disposed between the third lens and the fourth lens. Optionally, the imaging system may further include a filter for correcting color deviation and / or a protective glass for protecting a photosensitive element located on the imaging surface.

[0076] The imaging system according to the above embodiment of the present invention can use multiple lenses, such as the above five lenses. By reasonably allocating the focal length, surface shape, center thickness of each lens, and axial spacing between lenses, the imaging system has a larger imaging surface, a wide imaging range, and high imaging quality, and ensures that the imaging system is miniaturized.

[0077] In an exemplary embodiment, at least one of the mirror surfaces of each lens is an aspherical mirror surface, that is, at least one of the mirror surfaces from the object side of the first lens to the image side of the seventh lens is an aspherical mirror surface. The characteristics of the aspherical lens are: the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens with a constant curvature from the center of the lens to the periphery of the lens, the aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. After adopting the aspherical lens, the aberration that occurs during imaging can be eliminated as much as possible, thereby improving the imaging quality. Optionally, at least one of the object side and image side of each lens in the first lens, the second lens, the third lens, the fourth lens and the fifth lens is an aspherical mirror surface. Optionally, the object side and image side of each lens in the first lens, the second lens, the third lens, the fourth lens and the fifth lens are all aspherical mirror surfaces.

[0078] However, those skilled in the art should understand that, without departing from the technical solution claimed in the present application, the number of lenses constituting the imaging system can be changed to obtain the various results and advantages described in this specification. For example, although five lenses are described as an example in the embodiment, the imaging system is not limited to including five lenses, and the imaging system may also include other numbers of lenses if necessary.

[0079] The following further describes a specific embodiment of the imaging system applicable to the above embodiment with reference to the accompanying drawings. Specific embodiment 1

[0081] Figure 1Schematic diagram of the lens group structure of the imaging system embodiment 1 of the present invention. The imaging system includes, from the object side to the image side along the optical axis, a first lens E1, a second lens E2, a third lens E3, an aperture STO, a fourth lens E4, a fifth lens E5, a filter E6 and an imaging surface S13.

[0082] The first lens E1 has negative optical power, and its object side surface S1 is convex, and its image side surface S2 is concave. The second lens E2 has negative optical power, and its object side surface S3 is convex, and its image side surface S4 is concave. The third lens E3 has positive optical power, and its object side surface S5 is convex, and its image side surface S6 is concave. The fourth lens E4 has positive optical power, and its object side surface S7 is convex, and its image side surface S8 is convex. The fifth lens E5 has negative optical power, and its object side surface S9 is concave, and its image side surface S10 is convex. The filter E8 has an object side surface S11 and an image side surface S12. The light from the object passes through each surface of surfaces S1 to S12 in sequence and is finally imaged on the imaging surface S13.

[0083] As shown in Table 1, it is a basic parameter table of the imaging system of Example 1, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0084]

[0085] Table 1

[0086] As shown in Table 2, in Example 1, the total effective focal length of the imaging system is f=0.83 mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S13 of the imaging system is 3.20 mm, and half of the diagonal length of the effective pixel area on the imaging surface S13 is ImgH=1.18 mm. Semi-FOV, which is half of the maximum field of view of the optical imaging lens, is 75.0°.

[0087]

[0088] Table 2

[0089] The imaging system in Embodiment 1 satisfies:

[0090] CT4 / f=0.86; wherein CT4 is the center thickness of the fourth lens, and f is the effective focal length of the imaging system.

[0091] tan(Semi-FOV)=3.73; wherein Semi-FOV is half of the maximum field of view of the imaging system.

[0092] (Vd2-Vd3+Vd4) / 3=30.60; wherein Vd2, Vd3, and Vd4 are the dispersion coefficients of the second lens, the third lens, and the fourth lens, respectively.

[0093] (f2+f5) / f=-7.10; wherein f2 and f5 are the effective focal lengths of the second lens and the fifth lens respectively, and f is the effective focal length of the imaging system.

[0094] (f3+f4) / f=3.81; wherein f3 and f4 are the effective focal lengths of the third lens and the fourth lens respectively, and f is the effective focal length of the imaging system.

[0095] SD / ImgH=0.17; wherein SD is the maximum radius of the aperture stop, and ImgH is half of the diagonal length of the effective pixel area on the imaging surface.

[0096] f / EPD=2.20; wherein f is the effective focal length of the imaging system, and EPD is the entrance pupil diameter of the imaging system.

[0097] TTL / (CT3+T34+CT4)=2.35; wherein TTL is the distance from the object side of the first lens of the imaging system to the image plane on the optical axis, CT3 and CT4 are the center thicknesses of the third lens and the fourth lens respectively, and T34 is the distance from the image side of the third lens to the object side of the fourth lens on the optical axis.

[0098] TD / ImgH=2.14; wherein TD is the distance from the object side of the first lens to the image side of the fifth lens on the optical axis, and ImgH is half of the diagonal length of the effective pixel area on the imaging plane.

[0099] EPD / (ImgH+DT52)=0.19; wherein EPD is the entrance pupil diameter of the imaging system, ImgH is half the diagonal length of the effective pixel area on the imaging plane, and DT52 is the effective semi-aperture of the image side of the fifth lens.

[0100] (R7+R8) / (R7-R8)=0.75; wherein R7 and R8 are the curvature radii of the object side surface of the fourth lens and the image side surface of the fourth lens, respectively.

[0101] In Example 1, the object side surface and the image side surface of any one of the first lens E1 to the fifth lens E5 are aspherical surfaces. Table 3 shows the high-order coefficients A of the aspherical mirror surfaces S1-S14 that can be used in Example 1. 4 , A 6 , A 8 , A 10 , A 12 , A 14 , A 16 , A 18 and A 20 .

[0102] Face number A4 A6 A8 A10 A12 A14 A16 A18 A20 S1 -5.2853E-01 2.9147E+00 -9.9224E+00 1.8101E+01 -1.9056E+01 1.2115E+01 -4.6119E+00 9.6971E-01 -8.6717E-02 S2 -3.6497E+00 1.5041E+01 -2.4538E+01 -8.3639E+01 5.9134E+02 -1.5054E+03 1.9990E+03 -1.3640E+03 3.7618E+02 S3 7.4027E+00 -1.3808E+02 9.8555E+02 -3.7094E+03 8.2080E+03 -1.1046E+04 8.8720E+03 -3.8918E+03 7.1216E+02 S4 9.0347E+00 -2.7107E+02 1.6868E+03 1.3325E+04 -2.2743E+05 1.2533E+06 -3.4578E+06 4.8291E+06 -2.7225E+06 S5 2.1964E+00 -9.3122E+01 1.6863E+03 -1.7202E+04 1.1798E+05 -5.4829E+05 1.5995E+06 -2.5811E+06 1.7367E+06 S6 -6.3438E-01 1.6383E+02 -7.0264E+03 1.6550E+05 -1.9487E+06 5.8475E+06 1.0446E+08 -1.0846E+09 3.0949E+09 S7 -1.4477E+00 1.0492E+02 -4.8358E+03 1.2533E+05 -1.9190E+06 1.7683E+07 -9.5852E+07 2.8105E+08 -3.4584E+08 S8 1.0495E+01 -2.7191E+02 4.3373E+03 -4.9482E+04 3.9131E+05 -2.0677E+06 6.9392E+06 -1.3383E+07 1.1336E+07 S9 1.2666E+01 -2.1296E+02 2.5832E+03 -2.5037E+04 1.7878E+05 -8.7453E+05 2.7338E+06 -4.8857E+06 3.7705E+06 S10 6.2389E+00 -5.2531E+01 2.3621E+02 -7.1132E+02 1.4999E+03 -2.1460E+03 1.9342E+03 -9.7546E+02 2.0914E+02

[0103] Table 3

[0104] Figure 2a The distortion curve of the imaging system of Example 1 is shown, which indicates the distortion magnitude values ​​corresponding to different image heights. Figure 2b The axial chromatic aberration curve of the imaging system of Example 1 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Figure 2c FIG. 1 shows the astigmatism curve of the imaging system of Example 1, which indicates the meridional image plane curvature and the sagittal image plane curvature. Figure 2a to Figure 2c It can be seen from the figure that the imaging system provided in Example 1 can achieve good imaging quality. Specific embodiment 2

[0106] Figure 3 Schematic diagram of the lens group structure of the imaging system embodiment 2 of the present invention. The imaging system includes, from the object side to the image side along the optical axis, a first lens E1, a second lens E2, a third lens E3, an aperture STO, a fourth lens E4, a fifth lens E5, a filter E6 and an imaging surface S13.

[0107] The first lens E1 has positive focal power, and its object side surface S1 is convex, and its image side surface S2 is concave. The second lens E2 has negative focal power, and its object side surface S3 is convex, and its image side surface S4 is concave. The third lens E3 has positive focal power, and its object side surface S5 is convex, and its image side surface S6 is convex. The fourth lens E4 has positive focal power, and its object side surface S7 is convex, and its image side surface S8 is convex. The fifth lens E5 has negative focal power, and its object side surface S9 is concave, and its image side surface S10 is concave. The filter E8 has an object side surface S11 and an image side surface S12. The light from the object passes through each surface of surfaces S1 to S12 in sequence and is finally imaged on the imaging surface S13.

[0108] As shown in Table 4, it is a basic parameter table of the imaging system of Example 2, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0109]

[0110] Table 4

[0111] As shown in Table 5, in Example 2, the total effective focal length of the imaging system is f=0.83 mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S13 of the imaging system is 3.20 mm, and half of the diagonal length of the effective pixel area on the imaging surface S13 is ImgH=1.13 mm. Semi-FOV, which is half of the maximum field of view of the optical imaging lens, is 75.0°.

[0112]

[0113] Table 5

[0114] The imaging system in Embodiment 2 satisfies:

[0115] CT4 / f=0.79; wherein CT4 is the center thickness of the fourth lens, and f is the effective focal length of the imaging system.

[0116] tan(Semi-FOV)=3.74; wherein Semi-FOV is half of the maximum field of view of the imaging system.

[0117] (Vd2-Vd3+Vd4) / 3=30.60; wherein Vd2, Vd3, and Vd4 are the dispersion coefficients of the second lens, the third lens, and the fourth lens, respectively.

[0118] (f2+f5) / f=-2.34; wherein f2 and f5 are the effective focal lengths of the second lens and the fifth lens respectively, and f is the effective focal length of the imaging system.

[0119] (f3+f4) / f=2.93; wherein f3 and f4 are the effective focal lengths of the third lens and the fourth lens respectively, and f is the effective focal length of the imaging system.

[0120] SD / ImgH=0.20; wherein SD is the maximum radius of the aperture stop, and ImgH is half of the diagonal length of the effective pixel area on the imaging surface.

[0121] f / EPD=2.37; where f is the effective focal length of the imaging system, and EPD is the entrance pupil diameter of the imaging system.

[0122] TTL / (CT3+T34+CT4)=2.53; wherein TTL is the distance from the object side of the first lens of the imaging system to the image plane on the optical axis, CT3 and CT4 are the center thicknesses of the third lens and the fourth lens respectively, and T34 is the distance from the image side of the third lens to the object side of the fourth lens on the optical axis.

[0123] TD / ImgH=2.24; wherein TD is the distance from the object side of the first lens to the image side of the fifth lens on the optical axis, and ImgH is half of the diagonal length of the effective pixel area on the imaging plane.

[0124] EPD / (ImgH+DT52)=0.18; wherein EPD is the entrance pupil diameter of the imaging system, ImgH is half of the diagonal length of the effective pixel area on the imaging plane, and DT52 is the effective semi-aperture of the image side of the fifth lens.

[0125] (R7+R8) / (R7-R8)=0.67; wherein R7 and R8 are the curvature radii of the object side surface of the fourth lens and the image side surface of the fourth lens, respectively.

[0126] In Example 2, the object side surface and the image side surface of any one of the first lens E1 to the fifth lens E5 are aspherical surfaces. Table 6 shows the high-order coefficients A of the aspherical mirror surfaces S1-S14 that can be used in Example 2. 4 , A 6 , A 8 , A 10 , A 12 , A 14 , A 16 , A 18 and A 20 .

[0127] Face number A4 A6 A8 A10 A12 A14 A16 A18 A20 S1 -5.4500E-02 -1.9330E-01 4.2427E-01 -3.5213E-01 1.5710E-01 -3.7053E-02 3.5918E-03 -5.4500E-02 -1.9330E-01 S2 -3.7522E-01 1.6773E+00 -4.1639E+00 6.7405E+00 -6.5730E+00 3.5510E+00 -8.0346E-01 -3.7522E-01 1.6773E+00 S3 -4.3177E-01 3.3113E+00 -8.6462E+00 9.9169E+00 -4.6953E+00 9.3020E-02 4.1592E-01 -4.3177E-01 3.3113E+00 S4 9.3923E-01 -4.8534E+00 7.0567E+01 -5.7511E+02 1.7896E+03 -2.4551E+03 1.2650E+03 9.3923E-01 -4.8534E+00 S5 -7.4147E-02 2.9973E+00 -2.4560E+01 1.8177E+02 -9.7518E+02 2.3328E+03 -1.9473E+03 -7.4147E-02 2.9973E+00 S6 -6.4931E-02 2.9155E+01 -4.6704E+02 3.8979E+03 -1.8818E+04 5.7712E+04 -9.6951E+04 -6.4931E-02 2.9155E+01 S7 -2.6987E-01 -1.4366E+01 2.6743E+02 -2.3656E+03 1.1627E+04 -2.9797E+04 3.0575E+04 -2.6987E-01 -1.4366E+01 S8 -2.5614E+00 6.0443E+01 -8.9849E+02 6.7452E+03 -2.7196E+04 5.6320E+04 -4.6577E+04 -2.5614E+00 6.0443E+01 S9 1.2370E+00 7.0048E+00 -2.7881E+02 2.0095E+03 -6.7338E+03 1.1018E+04 -7.0973E+03 1.2370E+00 7.0048E+00 S10 -9.2904E-01 4.4511E+00 -3.3321E+01 1.2002E+02 -2.1447E+02 1.8899E+02 -6.5973E+01 -9.2904E-01 4.4511E+00

[0128] Table 6

[0129] Figure 4a The distortion curve of the imaging system of Example 2 is shown, which indicates the distortion magnitude values ​​corresponding to different image heights. Figure 4b The axial chromatic aberration curve of the imaging system of Example 2 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Figure 4c FIG. 2 shows the astigmatism curve of the imaging system of Example 2, which indicates the meridional image plane curvature and the sagittal image plane curvature. Figures 4a to 4c It can be seen from the figure that the imaging system provided in Example 2 can achieve good imaging quality. Specific embodiment 3

[0131] Figure 5 Schematic diagram of the lens group structure of the imaging system embodiment 3 of the present invention. The imaging system includes, from the object side to the image side along the optical axis, a first lens E1, a second lens E2, a third lens E3, an aperture STO, a fourth lens E4, a fifth lens E5, a filter E6 and an imaging surface S13.

[0132] The first lens E1 has positive focal power, and its object side surface S1 is convex, and its image side surface S2 is concave. The second lens E2 has negative focal power, and its object side surface S3 is convex, and its image side surface S4 is concave. The third lens E3 has positive focal power, and its object side surface S5 is convex, and its image side surface S6 is convex. The fourth lens E4 has positive focal power, and its object side surface S7 is convex, and its image side surface S8 is convex. The fifth lens E5 has negative focal power, and its object side surface S9 is concave, and its image side surface S10 is concave. The filter E8 has an object side surface S11 and an image side surface S12. The light from the object passes through each surface of surfaces S1 to S12 in sequence and is finally imaged on the imaging surface S13.

[0133] As shown in Table 7, it is a basic parameter table of the imaging system of Example 3, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0134]

[0135] Table 7

[0136] As shown in Table 8, in Example 3, the total effective focal length of the imaging system is f=0.83 mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S13 of the imaging system is 3.20 mm, and half of the diagonal length of the effective pixel area on the imaging surface S13 is ImgH=1.16 mm. Semi-FOV, which is half of the maximum field of view of the optical imaging lens, is 75.0°.

[0137]

[0138] Table 8

[0139] The imaging system in Embodiment 3 satisfies:

[0140] CT4 / f=0.80; wherein CT4 is the center thickness of the fourth lens, and f is the effective focal length of the imaging system.

[0141] tan(Semi-FOV)=3.74; wherein Semi-FOV is half of the maximum field of view of the imaging system.

[0142] (Vd2-Vd3+Vd4) / 3=30.60; wherein Vd2, Vd3, and Vd4 are the dispersion coefficients of the second lens, the third lens, and the fourth lens, respectively.

[0143] (f2+f5) / f=-2.21; wherein f2 and f5 are the effective focal lengths of the second lens and the fifth lens respectively, and f is the effective focal length of the imaging system.

[0144] (f3+f4) / f=2.82; wherein f3 and f4 are the effective focal lengths of the third lens and the fourth lens respectively, and f is the effective focal length of the imaging system.

[0145] SD / ImgH=0.19; wherein SD is the maximum radius of the aperture stop, and ImgH is half of the diagonal length of the effective pixel area on the imaging surface.

[0146] f / EPD=2.37; where f is the effective focal length of the imaging system, and EPD is the entrance pupil diameter of the imaging system.

[0147] TTL / (CT3+T34+CT4)=2.54; wherein TTL is the distance from the object side of the first lens of the imaging system to the image plane on the optical axis, CT3 and CT4 are the center thicknesses of the third lens and the fourth lens respectively, and T34 is the distance from the image side of the third lens to the object side of the fourth lens on the optical axis.

[0148] TD / ImgH=2.20; wherein TD is the distance from the object side of the first lens to the image side of the fifth lens on the optical axis, and ImgH is half of the diagonal length of the effective pixel area on the imaging plane.

[0149] EPD / (ImgH+DT52)=0.18; wherein EPD is the entrance pupil diameter of the imaging system, ImgH is half of the diagonal length of the effective pixel area on the imaging plane, and DT52 is the effective semi-aperture of the image side of the fifth lens.

[0150] (R7+R8) / (R7-R8)=0.70; wherein R7 and R8 are the curvature radii of the object side surface of the fourth lens and the image side surface of the fourth lens, respectively.

[0151] In Example 3, the object side surface and the image side surface of any one of the first lens E1 to the fifth lens E5 are aspherical surfaces. Table 9 shows the high-order coefficients A of the aspherical mirror surfaces S1-S14 that can be used in Example 3. 4 , A 6 , A 8 , A 10 , A 12 , A 14 , A 16 , A 18 and A 20 .

[0152] Face number A4 A6 A8 A10 A12 A14 A16 A18 A20 S1 -6.1284E-02 -1.7213E-01 4.0335E-01 -3.5598E-01 1.7141E-01 -4.3864E-02 4.6142E-03 -6.1284E-02 -1.7213E-01 S2 -4.1774E-01 1.9388E+00 -4.9795E+00 8.6043E+00 -9.1490E+00 5.3612E+00 -1.2936E+00 -4.1774E-01 1.9388E+00 S3 -4.4408E-01 3.0665E+00 -6.3601E+00 2.7471E+00 5.9932E+00 -7.6351E+00 2.5940E+00 -4.4408E-01 3.0665E+00 S4 1.1982E+00 -9.1929E+00 9.2849E+01 -6.1717E+02 1.7920E+03 -2.3745E+03 1.1966E+03 1.1982E+00 -9.1929E+00 S5 1.2820E-01 1.7010E+00 -3.4441E+01 4.2873E+02 -2.4652E+03 5.9729E+03 -5.1377E+03 1.2820E-01 1.7010E+00 S6 7.0153E-01 -9.7379E+00 9.8516E+02 -2.3385E+04 2.5254E+05 -1.2984E+06 2.5695E+06 7.0153E-01 -9.7379E+00 S7 -6.9072E-01 -1.5272E+00 7.8397E+01 -8.1630E+02 4.5061E+03 -1.2762E+04 1.4044E+04 -6.9072E-01 -1.5272E+00 S8 -2.1445E+00 5.1395E+01 -8.0225E+02 6.2181E+03 -2.5746E+04 5.4620E+04 -4.6146E+04 -2.1445E+00 5.1395E+01 S9 3.2615E+00 -1.9887E+01 -9.5642E+01 1.3350E+03 -5.4633E+03 1.0016E+04 -6.9894E+03 3.2615E+00 -1.9887E+01 S10 -6.0489E-01 1.2255E+00 -1.8293E+01 8.2895E+01 -1.6348E+02 1.5159E+02 -5.4376E+01 -6.0489E-01 1.2255E+00

[0153] Table 9

[0154] Figure 6a The distortion curve of the imaging system of Example 3 is shown, which indicates the distortion magnitude values ​​corresponding to different image heights. Figure 6b The axial chromatic aberration curve of the imaging system of Example 3 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Figure 6c FIG. 2 shows the astigmatism curve of the imaging system of Example 3, which indicates the meridional image plane curvature and the sagittal image plane curvature. Figures 6a to 6c It can be seen from the figure that the imaging system provided in Example 3 can achieve good imaging quality. Specific embodiment 4

[0156] Figure 7 Schematic diagram of the lens group structure of the imaging system embodiment 4 of the present invention. The imaging system includes, from the object side to the image side along the optical axis, a first lens E1, a second lens E2, a third lens E3, an aperture STO, a fourth lens E4, a fifth lens E5, a filter E6 and an imaging surface S13.

[0157] The first lens E1 has positive focal power, and its object side surface S1 is convex, and its image side surface S2 is convex. The second lens E2 has negative focal power, and its object side surface S3 is convex, and its image side surface S4 is concave. The third lens E3 has positive focal power, and its object side surface S5 is convex, and its image side surface S6 is convex. The fourth lens E4 has positive focal power, and its object side surface S7 is convex, and its image side surface S8 is convex. The fifth lens E5 has negative focal power, and its object side surface S9 is concave, and its image side surface S10 is convex. The filter E8 has an object side surface S11 and an image side surface S12. The light from the object passes through each surface of surfaces S1 to S12 in sequence and is finally imaged on the imaging surface S13.

[0158] As shown in Table 10, it is a basic parameter table of the imaging system of Example 4, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0159]

[0160] Table 10

[0161] As shown in Table 11, in Example 4, the total effective focal length of the imaging system is f=0.83 mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S13 of the imaging system is 3.20 mm, and half of the diagonal length of the effective pixel area on the imaging surface S13 is ImgH=1.13 mm. Semi-FOV, which is half of the maximum field of view of the optical imaging lens, is 75.0°.

[0162]

[0163] Table 11

[0164] The imaging system in Embodiment 4 satisfies:

[0165] CT4 / f=0.78; wherein CT4 is the center thickness of the fourth lens, and f is the effective focal length of the imaging system.

[0166] tan(Semi-FOV)=3.73; wherein Semi-FOV is half of the maximum field of view of the imaging system.

[0167] (Vd2-Vd3+Vd4) / 3=30.60; wherein Vd2, Vd3, and Vd4 are the dispersion coefficients of the second lens, the third lens, and the fourth lens, respectively.

[0168] (f2+f5) / f=-1.95; wherein f2 and f5 are the effective focal lengths of the second lens and the fifth lens respectively, and f is the effective focal length of the imaging system.

[0169] (f3+f4) / f=2.91; wherein f3 and f4 are the effective focal lengths of the third lens and the fourth lens respectively, and f is the effective focal length of the imaging system.

[0170] SD / ImgH=0.19; wherein SD is the maximum radius of the aperture stop, and ImgH is half of the diagonal length of the effective pixel area on the imaging surface.

[0171] f / EPD=2.23; wherein f is the effective focal length of the imaging system, and EPD is the entrance pupil diameter of the imaging system.

[0172] TTL / (CT3+T34+CT4)=2.53; wherein TTL is the distance from the object side of the first lens of the imaging system to the image plane on the optical axis, CT3 and CT4 are the center thicknesses of the third lens and the fourth lens respectively, and T34 is the distance from the image side of the third lens to the object side of the fourth lens on the optical axis.

[0173] TD / ImgH=2.20; wherein TD is the distance from the object side of the first lens to the image side of the fifth lens on the optical axis, and ImgH is half of the diagonal length of the effective pixel area on the imaging plane.

[0174] EPD / (ImgH+DT52)=0.20; wherein EPD is the entrance pupil diameter of the imaging system, ImgH is half of the diagonal length of the effective pixel area on the imaging plane, and DT52 is the effective semi-aperture of the image side of the fifth lens.

[0175] (R7+R8) / (R7-R8)=0.77; wherein R7 and R8 are the curvature radii of the object side surface of the fourth lens and the image side surface of the fourth lens, respectively.

[0176] In Example 4, the object side surface and the image side surface of any one of the first lens E1 to the fifth lens E5 are aspherical surfaces. Table 12 shows the high-order coefficients A of the aspherical mirror surfaces S1-S14 that can be used in Example 4. 4 , A 6 , A 8 , A 10 , A 12 , A 14 , A 16 , A 18 and A 20 .

[0177] Face number A4 A6 A8 A10 A12 A14 A16 A18 A20 S1 -6.1284E-02 -1.7213E-01 4.0335E-01 -3.5598E-01 1.7141E-01 -4.3864E-02 4.6142E-03 -6.1284E-02 -1.7213E-01 S2 -4.1774E-01 1.9388E+00 -4.9795E+00 8.6043E+00 -9.1490E+00 5.3612E+00 -1.2936E+00 -4.1774E-01 1.9388E+00 S3 -4.4408E-01 3.0665E+00 -6.3601E+00 2.7471E+00 5.9932E+00 -7.6351E+00 2.5940E+00 -4.4408E-01 3.0665E+00 S4 1.1982E+00 -9.1929E+00 9.2849E+01 -6.1717E+02 1.7920E+03 -2.3745E+03 1.1966E+03 1.1982E+00 -9.1929E+00 S5 1.2820E-01 1.7010E+00 -3.4441E+01 4.2873E+02 -2.4652E+03 5.9729E+03 -5.1377E+03 1.2820E-01 1.7010E+00 S6 7.0153E-01 -9.7379E+00 9.8516E+02 -2.3385E+04 2.5254E+05 -1.2984E+06 2.5695E+06 7.0153E-01 -9.7379E+00 S7 -6.9072E-01 -1.5272E+00 7.8397E+01 -8.1630E+02 4.5061E+03 -1.2762E+04 1.4044E+04 -6.9072E-01 -1.5272E+00 S8 -2.1445E+00 5.1395E+01 -8.0225E+02 6.2181E+03 -2.5746E+04 5.4620E+04 -4.6146E+04 -2.1445E+00 5.1395E+01 S9 3.2615E+00 -1.9887E+01 -9.5642E+01 1.3350E+03 -5.4633E+03 1.0016E+04 -6.9894E+03 3.2615E+00 -1.9887E+01 S10 -6.0489E-01 1.2255E+00 -1.8293E+01 8.2895E+01 -1.6348E+02 1.5159E+02 -5.4376E+01 -6.0489E-01 1.2255E+00

[0178] Table 12

[0179] Figure 8a The distortion curve of the imaging system of Example 4 is shown, which indicates the distortion magnitude values ​​corresponding to different image heights. Figure 8bThe axial chromatic aberration curve of the imaging system of Example 4 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Figure 8c FIG. 4 shows the astigmatism curve of the imaging system of Example 4, which indicates the meridional image plane curvature and the sagittal image plane curvature. Figures 8a to 8c It can be seen from the figure that the imaging system provided in Example 4 can achieve good imaging quality. Specific embodiment 5

[0181] Fig. 9 Schematic diagram of the lens group structure of the imaging system embodiment 5 of the present invention. The imaging system includes, from the object side to the image side along the optical axis, a first lens E1, a second lens E2, a third lens E3, an aperture STO, a fourth lens E4, a fifth lens E5, a filter E6 and an imaging surface S13.

[0182] The first lens E1 has positive focal power, and its object side surface S1 is convex, and its image side surface S2 is convex. The second lens E2 has negative focal power, and its object side surface S3 is convex, and its image side surface S4 is concave. The third lens E3 has positive focal power, and its object side surface S5 is convex, and its image side surface S6 is convex. The fourth lens E4 has positive focal power, and its object side surface S7 is convex, and its image side surface S8 is convex. The fifth lens E5 has negative focal power, and its object side surface S9 is concave, and its image side surface S10 is convex. The filter E8 has an object side surface S11 and an image side surface S12. The light from the object passes through each surface of surfaces S1 to S12 in sequence and is finally imaged on the imaging surface S13.

[0183] As shown in Table 13, it is a basic parameter table of the imaging system of Example 5, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0184]

[0185] Table 13

[0186] As shown in Table 14, in Example 5, the total effective focal length of the imaging system is f=0.83 mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S13 of the imaging system is 3.20 mm, and half of the diagonal length of the effective pixel area on the imaging surface S13 is ImgH=1.17 mm. Semi-FOV, which is half of the maximum field of view of the optical imaging lens, is 75.0°.

[0187]

[0188]

[0189] Table 14

[0190] The imaging system in Embodiment 5 satisfies:

[0191] CT4 / f=0.74; wherein CT4 is the center thickness of the fourth lens, and f is the effective focal length of the imaging system.

[0192] tan(Semi-FOV)=3.74; wherein Semi-FOV is half of the maximum field of view of the imaging system.

[0193] (Vd2-Vd3+Vd4) / 3=30.60; wherein Vd2, Vd3, and Vd4 are the dispersion coefficients of the second lens, the third lens, and the fourth lens, respectively.

[0194] (f2+f5) / f=-2.07; wherein f2 and f5 are the effective focal lengths of the second lens and the fifth lens respectively, and f is the effective focal length of the imaging system.

[0195] (f3+f4) / f=3.02; wherein f3 and f4 are the effective focal lengths of the third lens and the fourth lens respectively, and f is the effective focal length of the imaging system.

[0196] SD / ImgH=0.19; wherein SD is the maximum radius of the aperture stop, and ImgH is half of the diagonal length of the effective pixel area on the imaging surface.

[0197] f / EPD=2.17; wherein f is the effective focal length of the imaging system, and EPD is the entrance pupil diameter of the imaging system.

[0198] TTL / (CT3+T34+CT4)=2.51; wherein TTL is the distance from the object side of the first lens of the imaging system to the image plane on the optical axis, CT3 and CT4 are the center thicknesses of the third lens and the fourth lens respectively, and T34 is the distance from the image side of the third lens to the object side of the fourth lens on the optical axis.

[0199] TD / ImgH=2.11; wherein TD is the distance from the object side of the first lens to the image side of the fifth lens on the optical axis, and ImgH is half of the diagonal length of the effective pixel area on the imaging plane.

[0200] EPD / (ImgH+DT52)=0.20; wherein EPD is the entrance pupil diameter of the imaging system, ImgH is half of the diagonal length of the effective pixel area on the imaging plane, and DT52 is the effective semi-aperture of the image side of the fifth lens.

[0201] (R7+R8) / (R7-R8)=0.74; wherein R7 and R8 are the curvature radii of the object side surface of the fourth lens and the image side surface of the fourth lens, respectively.

[0202] In Example 5, the object side surface and the image side surface of any one of the first lens E1 to the fifth lens E5 are aspherical surfaces. Table 15 shows the high-order coefficients A of the aspherical mirror surfaces S1 to S14 that can be used in Example 5. 4 , A 6 , A 8 , A 10 , A 12 , A 14 , A 16 , A 18 and A 20 .

[0203] Face number A4 A6 A8 A10 A12 A14 A16 A18 A20 S1 -6.0356E-01 3.4307E+00 -1.0530E+01 1.8184E+01 -1.8932E+01 1.2219E+01 -4.7921E+00 1.0467E+00 -9.7703E-02 S2 -5.6681E-01 9.8029E+00 -7.1810E+01 3.0828E+02 -8.0970E+02 1.3310E+03 -1.3356E+03 7.4654E+02 -1.7763E+02 S3 1.4256E+00 -2.6690E+01 1.7575E+02 -5.7512E+02 1.0665E+03 -1.1731E+03 7.5330E+02 -2.5743E+02 3.5214E+01 S4 -2.9233E-01 -1.2772E+01 1.6053E+02 7.1682E+02 -1.6555E+04 8.7479E+04 -2.1669E+05 2.6399E+05 -1.2792E+05 S5 6.4419E-01 -2.2727E+01 5.2055E+02 -5.9045E+03 3.9665E+04 -1.6166E+05 3.8154E+05 -4.6386E+05 2.1200E+05 S6 -2.7784E-01 1.1785E+02 -4.2610E+03 8.7352E+04 -1.0165E+06 6.5586E+06 -2.0705E+07 1.9737E+07 1.6125E+07 S7 7.3448E-01 -4.3728E+01 1.8733E+03 -5.1560E+04 8.9024E+05 -9.6137E+06 6.2772E+07 -2.2608E+08 3.4342E+08 S8 3.6891E+00 4.5105E+01 -3.4001E+03 6.7132E+04 -7.0050E+05 4.3124E+06 -1.5735E+07 3.1524E+07 -2.6717E+07 S9 1.4906E+01 -2.7610E+02 3.3334E+03 -2.8923E+04 1.7975E+05 -7.6801E+05 2.1123E+06 -3.3403E+06 2.2946E+06 S10 3.1558E+00 -2.0601E+01 3.4340E+00 4.4215E+02 -2.1248E+03 4.9663E+03 -6.5728E+03 4.7349E+03 -1.4477E+03

[0204] Table 15

[0205] Fig.10a The distortion curve of the imaging system of Example 5 is shown, which indicates the distortion magnitude values ​​corresponding to different image heights. Fig.10b The axial chromatic aberration curve of the imaging system of Example 5 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Fig.10c FIG. 2 shows the astigmatism curve of the imaging system of Example 5, which indicates the meridional image plane curvature and the sagittal image plane curvature. Figures 10a to 10c It can be seen from the figure that the imaging system provided in Example 5 can achieve good imaging quality. Specific embodiment 6

[0207] Fig.11 Schematic diagram of the lens group structure of the imaging system embodiment 6 of the present invention. The imaging system includes, from the object side to the image side along the optical axis, a first lens E1, a second lens E2, a third lens E3, an aperture STO, a fourth lens E4, a fifth lens E5, a filter E6 and an imaging surface S13.

[0208] The first lens E1 has negative optical power, and its object side surface S1 is convex, and its image side surface S2 is concave. The second lens E2 has negative optical power, and its object side surface S3 is convex, and its image side surface S4 is concave. The third lens E3 has positive optical power, and its object side surface S5 is convex, and its image side surface S6 is convex. The fourth lens E4 has positive optical power, and its object side surface S7 is convex, and its image side surface S8 is convex. The fifth lens E5 has negative optical power, and its object side surface S9 is convex, and its image side surface S10 is convex. The filter E8 has an object side surface S11 and an image side surface S12. The light from the object passes through each surface of surfaces S1 to S12 in sequence and is finally imaged on the imaging surface S13.

[0209] As shown in Table 16, it is a basic parameter table of the imaging system of Example 6, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0210]

[0211] Table 16

[0212] As shown in Table 17, in Example 6, the total effective focal length f of the imaging system is 0.99 mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S13 of the imaging system is 2.71 mm, and half of the diagonal length of the effective pixel area on the imaging surface S13 is ImgH=0.98 mm. Semi-FOV, which is half of the maximum field of view of the optical imaging lens, is 76.7°.

[0213]

[0214]

[0215] Table 17

[0216] The imaging system in Embodiment 6 satisfies:

[0217] CT4 / f=0.51; wherein CT4 is the center thickness of the fourth lens, and f is the effective focal length of the imaging system.

[0218] tan(Semi-FOV)=4.22; wherein Semi-FOV is half of the maximum field of view of the imaging system.

[0219] (Vd2-Vd3+Vd4) / 3=6.80; wherein Vd2, Vd3, and Vd4 are the dispersion coefficients of the second lens, the third lens, and the fourth lens, respectively.

[0220] (f2+f5) / f=-3.26; wherein f2 and f5 are the effective focal lengths of the second lens and the fifth lens respectively, and f is the effective focal length of the imaging system.

[0221] (f3+f4) / f=2.49; wherein f3 and f4 are the effective focal lengths of the third lens and the fourth lens respectively, and f is the effective focal length of the imaging system.

[0222] SD / ImgH=0.22; wherein SD is the maximum radius of the aperture stop, and ImgH is half of the diagonal length of the effective pixel area on the imaging surface.

[0223] f / EPD=2.30; wherein f is the effective focal length of the imaging system, and EPD is the entrance pupil diameter of the imaging system.

[0224] TTL / (CT3+T34+CT4)=3.29; wherein TTL is the distance from the object side of the first lens of the imaging system to the image plane on the optical axis, CT3 and CT4 are the center thicknesses of the third lens and the fourth lens respectively, and T34 is the distance from the image side of the third lens to the object side of the fourth lens on the optical axis.

[0225] TD / ImgH=2.06; wherein TD is the distance from the object side of the first lens to the image side of the fifth lens on the optical axis, and ImgH is half of the diagonal length of the effective pixel area on the imaging plane.

[0226] EPD / (ImgH+DT52)=0.28; wherein EPD is the entrance pupil diameter of the imaging system, ImgH is half of the diagonal length of the effective pixel area on the imaging plane, and DT52 is the effective semi-aperture of the image side of the fifth lens.

[0227] (R7+R8) / (R7-R8)=0.62; wherein R7 and R8 are the curvature radii of the object side surface of the fourth lens and the image side surface of the fourth lens, respectively.

[0228] In Example 6, the object side surface and the image side surface of any one of the first lens E1 to the fifth lens E5 are aspherical surfaces. Table 18 shows the high-order coefficients A of the aspherical mirror surfaces S1 to S14 that can be used in Example 6. 4 , A 6 , A 8 , A 10 , A 12 , A 14 , A 16 , A 18 and A 20 .

[0229]

[0230]

[0231] Table 18

[0232] Fig.12a The distortion curve of the imaging system of Example 6 is shown, which indicates the distortion magnitude values ​​corresponding to different image heights. Figure 12b The axial chromatic aberration curve of the imaging system of Example 6 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Fig.12c FIG. 2 shows the astigmatism curve of the imaging system of Example 6, which indicates the meridional image plane curvature and the sagittal image plane curvature. Figures 12a to 12c It can be seen from the figure that the imaging system provided in Example 6 can achieve good imaging quality.

[0233] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, improvements, equivalent substitutions, etc. 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, It is characterized in that The imaging system has five lenses with optical power, and the five lenses include, in order from the object side to the image side along the optical axis: A first lens having positive or negative optical power, whose object side is convex; a second lens having negative optical power, with a convex object side surface and a concave image side surface; a third lens having positive refractive power and a convex object side surface; a fourth lens element having positive refractive power, with an object side convex surface and an image side convex surface; a fifth lens having negative optical power and a concave object side surface; The center thickness CT4 of the fourth lens and the effective focal length f of the imaging system satisfy: 0.5 <CT4 / f<0.9; Half of the maximum field of view of the imaging system Semi-FOV satisfies: 3.7<tan(Semi-FOV)≤4.22; The distance TD on the optical axis from the object side surface of the first lens to the image side surface of the fifth lens and half of the diagonal length of the effective pixel area on the imaging surface ImgH satisfy: 2.06≤TD / ImgH≤2.

24.

2. The imaging system according to claim 1, Features: The Abbe coefficient Vd2 of the second lens, the Abbe coefficient Vd3 of the third lens, and the Abbe coefficient Vd4 of the fourth lens satisfy: 6.8≤(Vd2-Vd3+Vd4) / 3≤30.

6.

3. The imaging system according to claim 1, Features: The effective focal length f2 of the second lens, the effective focal length f5 of the fifth lens and the effective focal length f of the imaging system satisfy: -7.1≤(f2+f5) / f≤-1.

95.

4. The imaging system according to claim 1, Features: The effective focal length f3 of the third lens, the effective focal length f4 of the fourth lens and the effective focal length f of the imaging system satisfy: 2.49≤(f3+f4) / f≤3.

81.

5. The imaging system according to claim 1, Features: The maximum radius SD of the aperture stop and half the diagonal length of the effective pixel area on the imaging plane ImgH satisfy: 0.17≤SD / ImgH<0.

25.

6. The imaging system according to claim 1, Features: The effective focal length f of the imaging system and the entrance pupil diameter EPD of the imaging system satisfy: 2.17≤f / EPD<2.

4.

7. The imaging system according to claim 1, Features: The distance TTL from the object side of the first lens to the image plane on the optical axis, the center thickness CT3 of the third lens, the center thickness CT4 of the fourth lens, and the distance T34 from the image side of the third lens to the object side of the fourth lens on the optical axis satisfy: 2.3 <TTL / (CT3+T34+CT4)<3.3。 8. The imaging system according to claim 1, Features: The entrance pupil diameter EPD of the imaging system, half of the diagonal length of the effective pixel area on the imaging surface ImgH and the effective half-aperture DT52 of the image side of the fifth lens meet the following requirements: 0.15 <EPD / (ImgH+DT52)<0.3。

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