An optical imaging system

Abstract

The present invention discloses an optical imaging system, which includes, in order from the object side to the image side along the optical axis: a first lens with positive optical power, whose object side is convex and image side is concave; a second lens with optical power; a third lens with positive optical power, whose object side is concave and image side is convex; and a fourth lens; wherein the on-axis distance TTL from the object side of the first lens to the imaging surface and the distance BFL from the image side of the last lens of the optical imaging system to the imaging surface on the optical axis satisfy: TTL / BFL<2.5; the value CT2 with the smallest center thickness among all lenses is the center thickness of the second lens on the optical axis. The reasonable matching of the optical power and the surface curvature between the lenses can effectively balance the various aberrations of the system and ensure the requirements of high imaging quality of the system. By controlling the ratio of the distance from the object side of the first lens to the distance from the image side of the last lens to the imaging surface on the optical axis, the system can be guaranteed to be ultra-thin.

Description

Technical Field

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

[0002] With the development of science and technology, the miniaturization trend of portable electronic products is becoming more and more obvious. The functions of mobile phones, laptops, smart wearable devices are more integrated and complete, which puts higher requirements on the imaging lenses they carry. In order to meet the needs of high imaging quality and high brightness, common imaging lenses usually increase the number of lenses and increase the total length of the system to obtain more adjustment space. It is difficult to take into account the characteristics of ultra-thin, high quality, light weight and low price at the same time.

[0003] In order to solve the above problems, the purpose of the present invention is to design an ultra-thin, small-distortion, high-definition 4-piece imaging lens. Summary of the invention

[0004] The present invention aims to provide an optical imaging system composed of four lenses, which has the characteristics of effectively balancing various aberrations of the system and ensuring the high imaging quality of the system.

[0005] The present invention provides an optical imaging system, which comprises, in order from the object side to the image side along the optical axis:

[0006] A first lens having positive refractive power, with a convex surface on the object side and a concave surface on the image side;

[0007] a second lens having optical power;

[0008] The third lens has positive refractive power, with a concave object side surface and a convex image side surface;

[0009] The fourth lens;

[0010] Among them, the on-axis distance TTL from the object side of the first lens to the imaging plane and the distance BFL from the image side of the last lens of the optical imaging system to the imaging plane on the optical axis satisfy: TTL / BFL<2.5; the value CT2 with the smallest center thickness among all lenses is the center thickness of the second lens on the optical axis.

[0011] According to an embodiment of the present invention, the maximum effective radius DT11 of the first lens objective side surface and the maximum effective radius DT21 of the second lens objective side surface satisfy: DT11 / DT21<1.0.

[0012] According to one embodiment of the present invention, the effective focal length f, relative F number Fno and half of the maximum field of view Semi-FOV of the optical imaging system satisfy: 3.3mm≦f×tan(Semi-FOV)×Fno≦4.5mm.

[0013] According to one embodiment of the present invention, a center thickness CT1 of the first lens on the optical axis, a center thickness CT2 of the second lens on the optical axis, a center thickness CT3 of the third lens on the optical axis, an air interval T12 between the first lens and the second lens on the optical axis, and an air interval T34 between the third lens and the fourth lens on the optical axis satisfy: 1.4≦(CT1+CT2+T12) / (CT3+T34)≦2.1.

[0014] According to one embodiment of the present invention, the effective focal length f of the optical imaging system, the effective focal length f1 of the first lens and the effective focal length f3 of the third lens satisfy: |(f3-f1) / f|≦3.0.

[0015] According to one embodiment of the present invention, the effective focal length f1 of the first lens and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 1.5≦f234 / f1≦3.5.

[0016] According to one embodiment of the present invention, the curvature radius R5 of the object side of the third lens, the curvature radius R6 of the image side of the third lens, the curvature radius R7 of the object side of the fourth lens, and the curvature radius R8 of the image side of the fourth lens satisfy: 1.0≦|R6×R8| / |R5×R7|≦2.0.

[0017] According to one embodiment of the present invention, the sum ∑AT of the air intervals on the optical axis between any two adjacent lenses with optical power from the first lens to the lens closest to the imaging surface and the sum ∑CT of the center thicknesses of all lenses on the optical axis satisfy: 2.0≦∑CT / ∑AT≦4.0.

[0018] According to one embodiment of the present invention, an axial distance InTL from the object side of the first lens to the image side of the penultimate lens and an axial distance TTL from the object side of the first lens to the imaging plane satisfy: 2.0≦TTL / InTL≦2.5.

[0019] According to one embodiment of the present invention, the on-axis distance SAG41 between the intersection of the object side surface of the fourth lens and the optical axis to the effective radius vertex of the object side surface of the fourth lens, and the on-axis distance SAG32 between the intersection of the image side surface of the third lens and the optical axis to the effective radius vertex of the image side surface of the third lens satisfy: 1.0≦(SAG32+SAG41) / (SAG32-SAG41)≦4.5.

[0020] According to an embodiment of the present invention, the maximum edge thickness ETmax of the first to fourth lenses and the edge thickness ET1 of the first lens satisfy: 1.0≦ETmax / ET1≦1.8.

[0021] According to one embodiment of the present invention, the effective focal length f of the optical imaging system and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 2.0≦f234 / f≦5.5.

[0022] The present invention also provides an optical imaging system, comprising:

[0023] A first lens having positive refractive power, with a convex surface on the object side and a concave surface on the image side;

[0024] a second lens having optical power;

[0025] The third lens has positive refractive power, with a concave object side surface and a convex image side surface;

[0026] a fourth lens having negative optical power;

[0027] The axial distance TTL from the object side of the first lens to the imaging plane and the half of the diagonal length of the effective pixel area on the imaging plane ImgH satisfy the following conditions: TTL / ImgH≦1.35.

[0028] According to an embodiment of the present invention, the maximum effective radius DT11 of the first lens objective side surface and the maximum effective radius DT21 of the second lens objective side surface satisfy: DT11 / DT21<1.0.

[0029] According to one embodiment of the present invention, the effective focal length f, relative F number Fno and half of the maximum field of view Semi-FOV of the optical imaging system satisfy: 3.3mm≦f×tan(Semi-FOV)×Fno≦4.5mm.

[0030] According to one embodiment of the present invention, a center thickness CT1 of the first lens on the optical axis, a center thickness CT2 of the second lens on the optical axis, a center thickness CT3 of the third lens on the optical axis, an air interval T12 between the first lens and the second lens on the optical axis, and an air interval T34 between the third lens and the fourth lens on the optical axis satisfy: 1.4≦(CT1+CT2+T12) / (CT3+T34)≦2.1.

[0031] According to one embodiment of the present invention, the effective focal length f of the optical imaging system, the effective focal length f1 of the first lens and the effective focal length f3 of the third lens satisfy: |(f3-f1) / f|≦3.0.

[0032] According to one embodiment of the present invention, the effective focal length f1 of the first lens and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 1.5≦f234 / f1≦3.5.

[0033] According to one embodiment of the present invention, the curvature radius R5 of the object side of the third lens, the curvature radius R6 of the image side of the third lens, the curvature radius R7 of the object side of the fourth lens, and the curvature radius R8 of the image side of the fourth lens satisfy: 1.0≦|R6×R8| / |R5×R7|≦2.0.

[0034] According to one embodiment of the present invention, the sum ∑AT of the air intervals on the optical axis between any two adjacent lenses with optical power from the first lens to the lens closest to the imaging surface and the sum ∑CT of the center thicknesses of all lenses on the optical axis satisfy: 2.0≦∑CT / ∑AT≦4.0.

[0035] According to one embodiment of the present invention, an axial distance InTL from the object side of the first lens to the image side of the penultimate lens and an axial distance TTL from the object side of the first lens to the imaging plane satisfy: 2.0≦TTL / InTL≦2.5.

[0036] According to one embodiment of the present invention, the on-axis distance SAG41 between the intersection of the object side surface of the fourth lens and the optical axis to the effective radius vertex of the object side surface of the fourth lens, and the on-axis distance SAG32 between the intersection of the image side surface of the third lens and the optical axis to the effective radius vertex of the image side surface of the third lens satisfy: 1.0≦(SAG32+SAG41) / (SAG32-SAG41)≦4.5.

[0037] According to an embodiment of the present invention, the maximum edge thickness ETmax of the first to fourth lenses and the edge thickness ET1 of the first lens satisfy: 1.0≦ETmax / ET1≦1.8.

[0038] According to one embodiment of the present invention, the effective focal length f of the optical imaging system and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 2.0≦f234 / f≦5.5.

[0039] Beneficial effects of the present invention:

[0040] The optical imaging system provided by the present invention includes multiple lenses, such as the first lens to the fourth lens. The reasonable matching of the focal power and the surface curvature between the lenses can effectively balance the various aberrations of the system and ensure the high imaging quality requirements of the system. By controlling the ratio of the distance from the object side of the first lens to the image side of the last lens to the imaging surface on the optical axis, the system can be ensured to have an ultra-thin feature. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] 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.

[0042] Figure 1 Schematic diagram of the lens group structure of embodiment 1 of the optical imaging system of the present invention;

[0043] Figure 2a to Figure 2d They are respectively an axial chromatic aberration curve, an astigmatism curve, a distortion curve and a magnification chromatic aberration curve of the optical imaging system embodiment 1 of the present invention;

[0044] Figure 3 Schematic diagram of the lens group structure of embodiment 2 of the optical imaging system of the present invention;

[0045] Figures 4a to 4d They are respectively an axial chromatic aberration curve, an astigmatism curve, a distortion curve and a magnification chromatic aberration curve of Embodiment 2 of the optical imaging system of the present invention;

[0046] Figure 5 Schematic diagram of the lens group structure of embodiment 3 of the optical imaging system of the present invention;

[0047] Figures 6a to 6d They are respectively an axial chromatic aberration curve, an astigmatism curve, a distortion curve and a magnification chromatic aberration curve of Embodiment 3 of the optical imaging system of the present invention;

[0048] Figure 7 Schematic diagram of the lens group structure of embodiment 4 of the optical imaging system of the present invention;

[0049] Figures 8a to 8d They are respectively an axial chromatic aberration curve, an astigmatism curve, a distortion curve and a magnification chromatic aberration curve of Embodiment 4 of the optical imaging system of the present invention;

[0050] Fig. 9 Schematic diagram of the lens group structure of embodiment 5 of the optical imaging system of the present invention;

[0051] Figures 10a to 10d They are respectively an axial chromatic aberration curve, an astigmatism curve, a distortion curve and a magnification chromatic aberration curve of Embodiment 5 of the optical imaging system of the present invention;

[0052] Fig.11 Schematic diagram of the lens group structure of embodiment 6 of the optical imaging system of the present invention;

[0053] Figures 12a to 12d They are respectively the axial chromatic aberration curve, the astigmatism curve, the distortion curve and the magnification chromatic aberration curve of the optical imaging system embodiment 6 of the present invention. DETAILED DESCRIPTION

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal way unless explicitly defined in this article.

[0060] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can 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 drawings and in combination with the embodiments.

[0061] Exemplary Embodiments

[0062] The optical imaging system of an exemplary embodiment of the present invention includes four lenses, which include: a first lens, a second lens, a third lens and a fourth lens in order from the object side to the image side along the optical axis, wherein each lens is independent of each other and has an air gap between each lens on the optical axis.

[0063] In this exemplary embodiment, along the optical axis from the object side to the image side, the following are included in order: a first lens with positive optical power, whose object side is convex and image side is concave; a second lens with optical power; a third lens with positive optical power, whose object side is concave and image side is convex; a fourth lens; wherein the on-axis distance TTL from the object side of the first lens to the imaging surface and the distance BFL from the image side of the last lens of the optical imaging system to the imaging surface on the optical axis satisfy: TTL / BFL<2.5; the value CT2 with the smallest center thickness among all lenses is the center thickness of the second lens on the optical axis. The reasonable matching of the optical power and surface curvature between the lenses can effectively balance the various aberrations of the system and ensure the high imaging quality requirements of the system. By controlling the ratio of the distance from the object side of the first lens to the image side of the last lens to the imaging surface on the optical axis, the system can be guaranteed to be ultra-thin.

[0064] According to one embodiment of the present invention, the maximum effective radius DT11 of the first lens object side and the maximum effective radius DT21 of the second lens object side satisfy: DT11 / DT21<1.0. By controlling the ratio of the maximum effective radius of the first lens object side and the second lens object side, on the one hand, the distortion and astigmatism of the system can be effectively corrected, and on the other hand, it is beneficial to the molding and assembly of each lens, so that the system has better processability. More specifically, the maximum effective radius DT11 of the first lens object side and the maximum effective radius DT21 of the second lens object side satisfy: DT11 / DT21<0.9.

[0065] According to one embodiment of the present invention, the effective focal length f, relative F number Fno and half of the maximum field of view angle Semi-FOV of the optical imaging system satisfy: 3.3mm≦f×tan(Semi-FOV)×Fno≦4.5mm. By controlling the product of the effective focal length, relative F number and half of the maximum field of view angle of the optical imaging system within a certain range, it can be ensured that the system has the characteristics of a large aperture within a certain imaging range, improve the imaging quality of the system in a dark environment, and help to compress the size of the optical imaging system. More specifically, the effective focal length f, relative F number Fno and half of the maximum field of view angle Semi-FOV of the optical imaging system satisfy: 3.2mm≦f×tan(Semi-FOV)×Fno≦4.3mm.

[0066] According to one embodiment of the present invention, the center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, the center thickness CT3 of the third lens on the optical axis, the air interval T12 between the first lens and the second lens on the optical axis, and the air interval T34 between the third lens and the fourth lens on the optical axis satisfy: 1.4≦(CT1+CT2+T12) / (CT3+T34)≦2.1. The ratio of the sum of the air intervals of the first lens, the second lens, and the first lens and the second lens on the optical axis to the center thickness of the third lens on the optical axis and the sum of the air intervals of the third lens and the fourth lens on the optical axis is conducive to correcting the primary aberration of the optical imaging lens and reducing the intensity of ghost images. In addition, it can ensure that the system has better assemblability. More specifically, the center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, the center thickness CT3 of the third lens on the optical axis, the air interval T12 between the first lens and the second lens on the optical axis, and the air interval T34 between the third lens and the fourth lens on the optical axis satisfy: 1.3≦(CT1+CT2+T12) / (CT3+T34)≦2.0.

[0067] According to one embodiment of the present invention, the effective focal length f of the optical imaging system, the effective focal length f1 of the first lens, and the effective focal length f3 of the third lens satisfy: |(f3-f1) / f|≦3.0. By controlling the ratio of the difference between the effective focal lengths of the third lens and the first lens of the optical imaging system to the effective focal length of the optical imaging system, the contribution of the first and third lenses to the optical power of the system can be effectively constrained, and it is beneficial to balance the off-axis aberrations of the optical system, so that the system obtains higher imaging quality. More specifically, the effective focal length f of the optical imaging system, the effective focal length f1 of the first lens, and the effective focal length f3 of the third lens satisfy: |(f3-f1) / f|≦2.9.

[0068] According to one embodiment of the present invention, the effective focal length f1 of the first lens and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 1.5≦f234 / f1≦3.5. By controlling the ratio of the combined focal length of the second lens, the third lens and the fourth lens to the effective focal length of the first lens within a certain range, on the one hand, the optical power of the system can be reasonably allocated and the aberration of the system can be balanced, and on the other hand, the sensitivity of the system can be effectively reduced and the production yield can be improved. More specifically, the effective focal length f1 of the first lens and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 1.4≦f234 / f1≦3.4.

[0069] According to one embodiment of the present invention, the radius of curvature R5 of the object side of the third lens, the radius of curvature R6 of the image side of the third lens, the radius of curvature R7 of the object side of the fourth lens, and the radius of curvature R8 of the image side of the fourth lens satisfy: 1.0≦|R6×R8| / |R5×R7|≦2.0. By controlling the lens curvatures of the third lens and the fourth lens, the system's chromatic aberration and distortion can be effectively corrected, and it is beneficial to control the deflection of light in the third lens and the fourth lens, thereby reducing or eliminating system ghost images. More specifically, the radius of curvature R5 of the object side of the third lens, the radius of curvature R6 of the image side of the third lens, the radius of curvature R7 of the object side of the fourth lens, and the radius of curvature R8 of the image side of the fourth lens satisfy: 0.9≦|R6×R8| / |R5×R7|≦1.9.

[0070] According to one embodiment of the present invention, the sum of the air spacings on the optical axis between any two adjacent lenses with optical power from the first lens to the lens closest to the imaging surface ∑AT and the sum of the center thicknesses of all lenses on the optical axis ∑CT satisfy: 2.0≦∑CT / ∑AT≦4.0. By controlling the ratio of the sum of the center thicknesses on the optical axis of all lenses to the sum of the air spacings on the optical axis between any two adjacent lenses with optical power from the first lens to the lens closest to the imaging surface, it is not only beneficial to the processing and assembly of each lens of the system, but also can ensure that the system has a smaller total optical length. More specifically, the sum of the air spacings on the optical axis between any two adjacent lenses with optical power from the first lens to the lens closest to the imaging surface ∑AT and the sum of the center thicknesses of all lenses on the optical axis ∑CT satisfy: 1.9≦∑CT / ∑AT≦3.9.

[0071] According to one embodiment of the present invention, the on-axis distance InTL from the object side of the first lens to the image side of the penultimate lens and the on-axis distance TTL from the object side of the first lens to the imaging plane satisfy: 2.0≦TTL / InTL≦2.5. By controlling the ratio of the on-axis distance from the object side of the first lens to the imaging plane and the on-axis distance from the object side of the first lens to the image side of the penultimate lens, the size of the system can be effectively compressed, and the last piece can be used to adjust the system's output light to better match the chip. More specifically, the on-axis distance InTL from the object side of the first lens to the image side of the penultimate lens and the on-axis distance TTL from the object side of the first lens to the imaging plane satisfy: 1.9≦TTL / InTL≦2.4.

[0072] According to one embodiment of the present invention, the on-axis distance SAG41 between the intersection of the fourth lens object side and the optical axis to the effective radius vertex of the fourth lens object side, and the on-axis distance SAG32 between the intersection of the third lens image side and the optical axis to the effective radius vertex of the third lens image side satisfy: 1.0≦(SAG32+SAG41) / (SAG32-SAG41)≦4.5. By controlling the on-axis distances of the third lens and the fourth lens, the inclination angles of the third and fourth lenses can be effectively controlled to ensure the processing and molding of the lens. In addition, it is beneficial to correct the field curvature and distortion of the system and improve the imaging quality of the system. More specifically, the on-axis distance SAG41 between the intersection of the fourth lens object side and the optical axis to the effective radius vertex of the fourth lens object side, and the on-axis distance SAG32 between the intersection of the third lens image side and the optical axis to the effective radius vertex of the third lens image side satisfy: 0.9≦(SAG32+SAG41) / (SAG32-SAG41)≦4.4.

[0073] According to one embodiment of the present invention, the maximum value ETmax of the edge thickness of the first to fourth lenses and the edge thickness ET1 of the first lens satisfy: 1.0≦ETmax / ET1≦1.8. By controlling the ratio of the maximum value of the edge thickness of the first to fourth lenses to the edge thickness of the first lens within a certain range, it is beneficial to uniformly distribute the thickness of each lens of the system, which is beneficial to the structural arrangement and later assembly. In addition, it is beneficial to reduce the optical size of the system. More specifically, the maximum value ETmax of the edge thickness of the first to fourth lenses and the edge thickness ET1 of the first lens satisfy: 0.9≦ETmax / ET1≦1.7.

[0074] According to one embodiment of the present invention, the effective focal length f of the optical imaging system and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 2.0≦f234 / f≦5.5. By controlling the ratio of the combined focal length of the second lens, the third lens and the fourth lens to the effective focal length of the optical imaging system, the spherical aberration and chromatic aberration of the system can be effectively corrected to improve the clarity of the optical imaging system. More specifically, the effective focal length f of the optical imaging system and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 1.9≦f234 / f≦5.4.

[0075] In this exemplary embodiment, the optical axis includes, in order from the object side to the image side: a first lens with positive optical power, whose object side convex surface and image side concave surface; a second lens with optical power; a third lens with positive optical power, whose object side concave surface and image side convex surface; a fourth lens with negative optical power; wherein the axial distance TTL from the object side surface of the first lens to the imaging plane and half the diagonal length of the effective pixel area on the imaging plane ImgH satisfy the following conditions: TTL / ImgH≦1.35.

[0076] According to one embodiment of the present invention, the maximum effective radius DT11 of the first lens object side and the maximum effective radius DT21 of the second lens object side satisfy: DT11 / DT21<1.0. By controlling the ratio of the maximum effective radius of the first lens object side and the second lens object side, on the one hand, the distortion and astigmatism of the system can be effectively corrected, and on the other hand, it is beneficial to the molding and assembly of each lens, so that the system has better processability. More specifically, the maximum effective radius DT11 of the first lens object side and the maximum effective radius DT21 of the second lens object side satisfy: DT11 / DT21<0.9.

[0077] According to one embodiment of the present invention, the effective focal length f, relative F number Fno and half of the maximum field of view angle Semi-FOV of the optical imaging system satisfy: 3.3mm≦f×tan(Semi-FOV)×Fno≦4.5mm. By controlling the product of the effective focal length, relative F number and half of the maximum field of view angle of the optical imaging system within a certain range, it can be ensured that the system has the characteristics of a large aperture within a certain imaging range, improve the imaging quality of the system in a dark environment, and help to compress the size of the optical imaging system. More specifically, the effective focal length f, relative F number Fno and half of the maximum field of view angle Semi-FOV of the optical imaging system satisfy: 3.2mm≦f×tan(Semi-FOV)×Fno≦4.3mm.

[0078] According to one embodiment of the present invention, the center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, the center thickness CT3 of the third lens on the optical axis, the air interval T12 between the first lens and the second lens on the optical axis, and the air interval T34 between the third lens and the fourth lens on the optical axis satisfy: 1.4≦(CT1+CT2+T12) / (CT3+T34)≦2.1. The ratio of the sum of the air intervals of the first lens, the second lens, and the first lens and the second lens on the optical axis to the center thickness of the third lens on the optical axis and the sum of the air intervals of the third lens and the fourth lens on the optical axis is conducive to correcting the primary aberration of the optical imaging lens and reducing the intensity of ghost images. In addition, it can ensure that the system has better assemblability. More specifically, the center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, the center thickness CT3 of the third lens on the optical axis, the air interval T12 between the first lens and the second lens on the optical axis, and the air interval T34 between the third lens and the fourth lens on the optical axis satisfy: 1.3≦(CT1+CT2+T12) / (CT3+T34)≦2.0.

[0079] According to one embodiment of the present invention, the effective focal length f of the optical imaging system, the effective focal length f1 of the first lens, and the effective focal length f3 of the third lens satisfy: |(f3-f1) / f|≦3.0. By controlling the ratio of the difference between the effective focal lengths of the third lens and the first lens of the optical imaging system to the effective focal length of the optical imaging system, the contribution of the first and third lenses to the optical power of the system can be effectively constrained, and it is beneficial to balance the off-axis aberrations of the optical system, so that the system obtains higher imaging quality. More specifically, the effective focal length f of the optical imaging system, the effective focal length f1 of the first lens, and the effective focal length f3 of the third lens satisfy: |(f3-f1) / f|≦2.9.

[0080] According to one embodiment of the present invention, the effective focal length f1 of the first lens and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 1.5≦f234 / f1≦3.5. By controlling the ratio of the combined focal length of the second lens, the third lens and the fourth lens to the effective focal length of the first lens within a certain range, on the one hand, the optical power of the system can be reasonably allocated and the aberration of the system can be balanced, and on the other hand, the sensitivity of the system can be effectively reduced and the production yield can be improved. More specifically, the effective focal length f1 of the first lens and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 1.4≦f234 / f1≦3.4.

[0081] According to one embodiment of the present invention, the radius of curvature R5 of the object side of the third lens, the radius of curvature R6 of the image side of the third lens, the radius of curvature R7 of the object side of the fourth lens, and the radius of curvature R8 of the image side of the fourth lens satisfy: 1.0≦|R6×R8| / |R5×R7|≦2.0. By controlling the lens curvatures of the third lens and the fourth lens, the system's chromatic aberration and distortion can be effectively corrected, and it is beneficial to control the deflection of light in the third lens and the fourth lens, thereby reducing or eliminating system ghost images. More specifically, the radius of curvature R5 of the object side of the third lens, the radius of curvature R6 of the image side of the third lens, the radius of curvature R7 of the object side of the fourth lens, and the radius of curvature R8 of the image side of the fourth lens satisfy: 0.9≦|R6×R8| / |R5×R7|≦1.9.

[0082] According to one embodiment of the present invention, the sum of the air spacings on the optical axis between any two adjacent lenses with optical power from the first lens to the lens closest to the imaging surface ∑AT and the sum of the center thicknesses of all lenses on the optical axis ∑CT satisfy: 2.0≦∑CT / ∑AT≦4.0. By controlling the ratio of the sum of the center thicknesses on the optical axis of all lenses to the sum of the air spacings on the optical axis between any two adjacent lenses with optical power from the first lens to the lens closest to the imaging surface, it is not only beneficial to the processing and assembly of each lens of the system, but also can ensure that the system has a smaller total optical length. More specifically, the sum of the air spacings on the optical axis between any two adjacent lenses with optical power from the first lens to the lens closest to the imaging surface ∑AT and the sum of the center thicknesses of all lenses on the optical axis ∑CT satisfy: 1.9≦∑CT / ∑AT≦3.9.

[0083] According to one embodiment of the present invention, the on-axis distance InTL from the object side of the first lens to the image side of the penultimate lens and the on-axis distance TTL from the object side of the first lens to the imaging plane satisfy: 2.0≦TTL / InTL≦2.5. By controlling the ratio of the on-axis distance from the object side of the first lens to the imaging plane and the on-axis distance from the object side of the first lens to the image side of the penultimate lens, the size of the system can be effectively compressed, and the last piece can be used to adjust the system's output light to better match the chip. More specifically, the on-axis distance InTL from the object side of the first lens to the image side of the penultimate lens and the on-axis distance TTL from the object side of the first lens to the imaging plane satisfy: 1.9≦TTL / InTL≦2.4.

[0084] According to one embodiment of the present invention, the on-axis distance SAG41 between the intersection of the fourth lens object side and the optical axis to the effective radius vertex of the fourth lens object side, and the on-axis distance SAG32 between the intersection of the third lens image side and the optical axis to the effective radius vertex of the third lens image side satisfy: 1.0≦(SAG32+SAG41) / (SAG32-SAG41)≦4.5. By controlling the on-axis distances of the third lens and the fourth lens, the inclination angles of the third and fourth lenses can be effectively controlled to ensure the processing and molding of the lens. In addition, it is beneficial to correct the field curvature and distortion of the system and improve the imaging quality of the system. More specifically, the on-axis distance SAG41 between the intersection of the fourth lens object side and the optical axis to the effective radius vertex of the fourth lens object side, and the on-axis distance SAG32 between the intersection of the third lens image side and the optical axis to the effective radius vertex of the third lens image side satisfy: 0.9≦(SAG32+SAG41) / (SAG32-SAG41)≦4.4.

[0085] According to one embodiment of the present invention, the maximum value ETmax of the edge thickness of the first to fourth lenses and the edge thickness ET1 of the first lens satisfy: 1.0≦ETmax / ET1≦1.8. By controlling the ratio of the maximum value of the edge thickness of the first to fourth lenses to the edge thickness of the first lens within a certain range, it is beneficial to uniformly distribute the thickness of each lens of the system, which is beneficial to the structural arrangement and later assembly. In addition, it is beneficial to reduce the optical size of the system. More specifically, the maximum value ETmax of the edge thickness of the first to fourth lenses and the edge thickness ET1 of the first lens satisfy: 0.9≦ETmax / ET1≦1.7.

[0086] According to one embodiment of the present invention, the effective focal length f of the optical imaging system and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 2.0≦f234 / f≦5.5. By controlling the ratio of the combined focal length of the second lens, the third lens and the fourth lens to the effective focal length of the optical imaging system, the spherical aberration and chromatic aberration of the system can be effectively corrected to improve the clarity of the optical imaging system. More specifically, the effective focal length f of the optical imaging system and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 1.9≦f234 / f≦5.4.

[0087] In this exemplary embodiment, the object side surface and the image side surface of any lens of the first lens E1 to the fourth lens E4 are both aspherical surfaces, and the surface shape x of each aspherical lens can be defined by, but not limited to, the following aspherical surface formula:

[0088]

[0089] 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.

[0090] In this exemplary embodiment, the optical imaging system may further include a stop. The stop may be disposed at an appropriate position as required, for example, the stop may be disposed between the object side and the first lens. Optionally, the optical 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.

[0091] The optical imaging system according to the above embodiment of the present invention can use multiple lenses, such as the above four lenses. By reasonably allocating the focal length, surface shape, center thickness of each lens, and axial spacing between lenses, the optical imaging system has a larger imaging surface, a wide imaging range, and high imaging quality, and ensures the ultra-thinness of the mobile phone.

[0092] 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 fourth lens is an aspherical mirror surface. The characteristics of an 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, an aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. After adopting an 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 and the fourth 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 and the fourth lens are all aspherical mirror surfaces.

[0093] 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 optical imaging system can be changed to obtain the various results and advantages described in this specification. For example, although four lenses are described as an example in the embodiment, the optical imaging system is not limited to including four lenses, and the optical imaging system may also include other numbers of lenses if necessary.

[0094] Specific embodiments of the optical imaging system applicable to the above embodiments are further described below with reference to the accompanying drawings. Specific embodiment 1

[0096] Figure 1Schematic diagram of the lens group structure of embodiment 1 of the optical imaging system of the present invention. The optical imaging system includes, in order from the object side to the image side along the optical axis: an aperture STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a filter E5 and an imaging surface S11.

[0097] The first lens E1 has positive power, its object side surface S1 is convex, and the image side surface S2 is concave. The second lens E2 has negative power, its object side surface S3 is concave, and the image side surface S4 is concave. The third lens E3 has positive power, its object side surface S5 is concave, and the image side surface S6 is convex. The fourth lens E4 has negative power, its object side surface S7 is convex, and the image side surface S8 is concave. The filter E5 has an object side surface S9 and an image side surface S10. The light from the object passes through each surface of surfaces S1 to S10 in sequence and is finally imaged on the imaging surface S11.

[0098] As shown in Table 1, it is a basic parameter table of the optical imaging system of Example 1, wherein the units of the radius of curvature, thickness, and focal length are all millimeters (mm).

[0099]

[0100]

[0101] Table 1

[0102] As shown in Table 2, in Example 1, the total effective focal length of the optical imaging system is f=1.82 mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S11 of the optical imaging system is 2.40 mm, and half of the diagonal length of the effective pixel area on the imaging surface S11 is ImgH=1.88 mm. Half of the maximum field of view of the optical imaging lens Semi-FOV=45.51°.

[0103]

[0104] Table 2

[0105] The optical imaging system in Example 1 satisfies:

[0106] TTL / BFL=2.46. TTL is the distance on the axis from the object side of the first lens to the imaging surface; BFL is the distance on the optical axis from the image side of the last lens of the optical imaging system to the imaging surface.

[0107] TTL / ImgH=1.28, where TTL is the axial distance from the object side of the first lens to the imaging plane, and ImgH is half of the diagonal length of the effective pixel area on the imaging plane.

[0108] DT11 / DT21=0.90, wherein DT11 is the maximum effective radius of the object side of the first lens; DT21 is the maximum effective radius of the object side of the second lens.

[0109] f×tan(Semi-FOV)×Fno=4.17, where f is the effective focal length of the optical imaging system, Fno is the relative F number, and Semi-FOV is half of the maximum field of view of the optical imaging system.

[0110] (CT1+CT2+T12) / (CT3+T34)=1.41, wherein CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, CT3 is the center thickness of the third lens on the optical axis, T12 is the air spacing between the first lens and the second lens on the optical axis, and T34 is the air spacing between the third lens and the fourth lens on the optical axis.

[0111] |(f3-f1) / f|=1.72, wherein f is the effective focal length of the optical imaging system, f1 is the effective focal length of the first lens, and f3 is the effective focal length of the third lens.

[0112] f234 / f1=3.24, wherein f1 is the effective focal length of the first lens, and f234 is the combined focal length of the second lens, the third lens, and the fourth lens.

[0113] |R6×R8| / |R5×R7|=1.46, wherein R5 is the radius of curvature of the object side of the third lens, and R6 is the radius of curvature of the image side of the third lens; R7 is the radius of curvature of the object side of the fourth lens, and R8 is the radius of curvature of the image side of the fourth lens.

[0114] ∑CT / ∑AT=2.29, wherein ∑AT is the sum of the air intervals on the optical axis between any two adjacent lenses with optical power from the first lens to the lens closest to the imaging surface; ∑CT is the sum of the center thicknesses of all lenses on the optical axis.

[0115] TTL / InTL=2.27, where InTL is the axial distance from the object side of the first lens to the image side of the penultimate lens.

[0116] (SAG32+SAG41) / (SAG32-SAG41)=4.14, wherein SAG41 is the on-axis distance between the intersection of the object side surface of the fourth lens and the optical axis to the vertex of the effective radius of the object side surface of the fourth lens, and SAG32 is the on-axis distance between the intersection of the image side surface of the third lens and the optical axis to the vertex of the effective radius of the image side surface of the third lens.

[0117] ETmax / ET1=1.38, wherein ETmax is the maximum edge thickness of the first lens to the fourth lens, and ET1 is the edge thickness of the first lens.

[0118] f234 / f=4.00, wherein f is the effective focal length of the optical imaging system, and f234 is the combined focal length of the second lens, the third lens, and the fourth lens.

[0119] In Example 1, the object side surface and the image side surface of any one of the first lens E1 to the fourth lens E4 are aspherical surfaces. Table 3 shows the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32, A33, A34, A35, A36, A37, A38, A39, A40, A41, A42, A43, A44, A45, A46, A47, A48, A49, A50, A51, A52, A53, A54, A55, A56, A57, A58, A5 10 , A 12 , A 14 , A 16 , A 18 , A 20 and A 22 .

[0120] Face number A4 A6 A8 A10 A12 S1 -3.7532E-01 2.4999E+01 -7.5999E+02 1.3258E+04 -1.3827E+05 S2 7.1255E-02 -1.3305E+01 4.3416E+02 -8.4561E+03 9.1906E+04 S3 -1.4886E+00 1.4033E+01 -3.6025E+02 4.2171E+03 -2.8681E+04 S4 -7.2276E-01 7.3283E+00 -1.0387E+02 7.5541E+02 -3.1787E+03 S5 3.6241E-01 -4.2360E-01 1.6155E+01 -5.3782E+01 2.9620E+01 S6 -2.2810E+00 1.5757E+01 -2.7598E+01 -2.8765E+02 2.3809E+03 S7 -5.2282E+00 2.0674E+01 -6.7007E+01 1.5584E+02 -2.4855E+02 S8 -4.4824E+00 1.5488E+01 -4.4131E+01 9.2627E+01 -1.3915E+02 Face number A14 A16 A18 A20 A22 S1 8.4743E+05 -2.8117E+06 3.8864E+06 0.0000E+00 0.0000E+00 S2 -5.6603E+05 1.8401E+06 -2.4590E+06 0.0000E+00 0.0000E+00 S3 1.0299E+05 -1.4824E+05 0.0000E+00 0.0000E+00 0.0000E+00 S4 7.3053E+03 -6.7064E+03 0.0000E+00 0.0000E+00 0.0000E+00 S5 1.4243E+02 -2.3836E+02 0.0000E+00 0.0000E+00 0.0000E+00 S6 -7.7233E+03 1.2837E+04 -1.0847E+04 3.7006E+03 0.0000E+00 S7 2.6382E+02 -1.7675E+02 6.7241E+01 -1.1033E+01 0.0000E+00 S8 1.4657E+02 -1.0526E+02 4.8963E+01 -1.3284E+01 1.5963E+00

[0121] Table 3

[0122] Figure 2a The axial chromatic aberration curve of the optical imaging system of Example 1 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Figure 2b An astigmatism curve of the optical imaging system of Example 1 is shown, which indicates meridional field curvature and sagittal field curvature. Figure 2c The distortion curve of the optical imaging system of Example 1 is shown, which represents the distortion magnitude values ​​corresponding to different image heights. Figure 2d The magnification chromatic aberration curve of the optical imaging system of Example 1 is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the lens. Figure 2a to Figure 2d It can be seen from the figure that the optical imaging system provided in Example 1 can achieve good imaging quality. Specific embodiment 2

[0124] Figure 3 Schematic diagram of the lens group structure of embodiment 2 of the optical imaging system of the present invention. The optical imaging system includes, in order from the object side to the image side along the optical axis: an aperture STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a filter E5 and an imaging surface S11.

[0125] The first lens E1 has positive power, its object side surface S1 is convex, and the image side surface S2 is concave. The second lens E2 has negative power, its object side surface S3 is convex, and the image side surface S4 is concave. The third lens E3 has positive power, its object side surface S5 is concave, and the image side surface S6 is convex. The fourth lens E4 has negative power, its object side surface S7 is convex, and the image side surface S8 is concave. The filter E5 has an object side surface S9 and an image side surface S10. The light from the object passes through each surface of surfaces S1 to S10 in sequence and is finally imaged on the imaging surface S11.

[0126] As shown in Table 4, it is a basic parameter table of the optical imaging system of Example 2, wherein the units of the radius of curvature, thickness, and focal length are all millimeters (mm).

[0127]

[0128] Table 4

[0129] As shown in Table 5, in Example 2, the total effective focal length of the optical imaging system is f=1.61 mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S11 of the optical imaging system is 2.25 mm, and half of the diagonal length of the effective pixel area on the imaging surface S11 is ImgH=1.75 mm. Semi-FOV, which is half of the maximum field of view of the optical imaging lens, is 46.44°.

[0130]

[0131]

[0132] Table 5

[0133] In Example 2, the object side surface and the image side surface of any one of the first lens E1 to the fourth lens E4 are aspherical surfaces. Table 6 shows the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32, A33, A34, A35, A36, A37, A38, A39, A40, A41, A42, A43, A44, A45, A46, A47, A48, A49, A50, A51, A52, A53, A54, A55, A56, A57, A58, A5 10 , A 12 , A 14 , A 16 , A 18 , A 20 and A 22 .

[0134] Face number A4 A6 A8 A10 A12 A14 S1 3.1624E+02 -2.5849E+04 1.3223E+06 -4.5217E+07 1.0778E+09 -1.8375E+10 S2 -6.9234E+01 3.8204E+03 -9.3862E+04 -8.9168E+05 1.3534E+08 -4.5648E+09 S3 3.1781E+02 -2.5626E+04 1.2820E+06 -4.3115E+07 1.0150E+09 -1.7125E+10 S4 2.2130E+01 -1.6881E+03 5.6960E+04 -1.2300E+06 1.8357E+07 -1.9595E+08 S5 -5.7695E+01 8.2449E+02 -7.5055E+03 2.7326E+04 2.0305E+05 -3.2524E+06 S6 -1.6672E+01 1.2512E+03 -2.5558E+04 3.1340E+05 -2.6069E+06 1.5423E+07 S7 4.5900E+01 -2.7861E+02 1.2555E+03 -3.8082E+03 6.7385E+03 -2.1125E+03 S8 6.9931E+00 4.9227E+01 -6.0185E+02 3.3424E+03 -1.1978E+04 2.9969E+04 Face number A16 A18 A20 A22 A24 S1 2.2694E+11 -2.0336E+12 1.3082E+13 -5.8817E+13 1.7532E+14 S2 8.8532E+10 -1.1234E+12 9.6430E+12 -5.5670E+13 2.0742E+14 S3 2.0950E+11 -1.8602E+12 1.1860E+13 -5.2883E+13 1.5647E+14 S4 1.5203E+09 -8.5994E+09 3.5117E+10 -1.0084E+11 1.9312E+11 S5 1.9148E+07 -5.6742E+07 5.6317E+07 1.5161E+08 -5.3945E+08 S6 -6.6159E+07 2.0641E+08 -4.6360E+08 7.3000E+08 -7.6451E+08 S7 -2.2979E+04 6.8231E+04 -1.0490E+05 1.0023E+05 -5.9894E+04 S8 -5.3849E+04 6.9973E+04 -6.5211E+04 4.2489E+04 -1.8371E+04

[0135] Table 6

[0136] Figure 4a The axial chromatic aberration curve of the optical imaging system of Example 2 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Figure 4bAn astigmatism curve of the optical imaging system of Example 2 is shown, which represents the meridional field curvature and the sagittal field curvature. Figure 4c The distortion curve of the optical imaging system of Example 2 is shown, which represents the distortion magnitude values ​​corresponding to different image heights. Figure 4d The magnification chromatic aberration curve of the optical imaging system of Example 2 is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the lens. Figures 4a to 4d It can be seen from the figure that the optical imaging system provided in Example 2 can achieve good imaging quality. Specific embodiment 3

[0138] Figure 5 Schematic diagram of the lens group structure of embodiment 3 of the optical imaging system of the present invention. The optical imaging system includes, in order from the object side to the image side along the optical axis: an aperture STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a filter E5 and an imaging surface S11.

[0139] The first lens E1 has positive focal power, its object side surface S1 is convex, and the image side surface S2 is concave. The second lens E2 has positive focal power, its object side surface S3 is convex, and the image side surface S4 is concave. The third lens E3 has positive focal power, its object side surface S5 is concave, and the image side surface S6 is convex. The fourth lens E4 has negative focal power, its object side surface S7 is convex, and the image side surface S8 is concave. The filter E5 has an object side surface S9 and an image side surface S10. The light from the object passes through each surface of surfaces S1 to S10 in sequence and is finally imaged on the imaging surface S11.

[0140] As shown in Table 7, it is a basic parameter table of the optical imaging system of Example 3, wherein the units of the radius of curvature, thickness, and focal length are all millimeters (mm).

[0141]

[0142] Table 7

[0143] As shown in Table 8, in Example 3, the total effective focal length f of the optical imaging system is 1.74 mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S11 of the optical imaging system is 2.46 mm, and half of the diagonal length of the effective pixel area on the imaging surface S11 is ImgH=1.83 mm. Semi-FOV, which is half of the maximum field of view of the optical imaging lens, is 45.40°.

[0144]

[0145] Table 8

[0146] In Example 3, the object side surface and the image side surface of any one of the first lens E1 to the fourth lens E4 are aspherical surfaces. Table 9 shows the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32, A33, A34, A35, A36, A37, A38, A39, A40, A41, A42, A43, A44, A45, A46, A47, A48, A49, A50, A51, A52, A53, A54, A55, A56, A57, A58, A5 10 , A 12 , A 14 , A 16 , A 18 , A 20 and A 22 .

[0147]

[0148]

[0149] Table 9

[0150] Figure 6a The axial chromatic aberration curve of the optical imaging system of Example 3 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Figure 6b An astigmatism curve of the optical imaging system of Example 3 is shown, which indicates meridional field curvature and sagittal field curvature. Figure 6c The distortion curve of the optical imaging system of Example 3 is shown, which represents the distortion magnitude values ​​corresponding to different image heights. Figure 6d The magnification chromatic aberration curve of the optical imaging system of Example 3 is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the lens. Figures 6a to 6d It can be seen from the figure that the optical imaging system provided in Example 3 can achieve good imaging quality. Specific embodiment 4

[0152] Figure 7 Schematic diagram of the lens group structure of embodiment 4 of the optical imaging system of the present invention. The optical imaging system includes, in order from the object side to the image side along the optical axis: an aperture STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a filter E5 and an imaging surface S11.

[0153] The first lens E1 has positive power, its object side surface S1 is convex, and the image side surface S2 is concave. The second lens E2 has negative power, its object side surface S3 is convex, and the image side surface S4 is concave. The third lens E3 has positive power, its object side surface S5 is concave, and the image side surface S6 is convex. The fourth lens E4 has negative power, its object side surface S7 is convex, and the image side surface S8 is concave. The filter E5 has an object side surface S9 and an image side surface S10. The light from the object passes through each surface of surfaces S1 to S10 in sequence and is finally imaged on the imaging surface S11.

[0154] As shown in Table 10, it is a basic parameter table of the optical imaging system of Example 4, wherein the units of the radius of curvature, thickness, and focal length are all millimeters (mm).

[0155]

[0156]

[0157] Table 10

[0158] As shown in Table 11, in Example 4, the total effective focal length f of the optical imaging system is 1.76 mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S11 of the optical imaging system is 2.46 mm, and half of the diagonal length of the effective pixel area on the imaging surface S11 is ImgH=1.83 mm. Half of the maximum field of view angle Semi-FOV of the optical imaging lens is 45.29°.

[0159]

[0160] Table 11

[0161] In Example 4, the object side surface and the image side surface of any one of the first lens E1 to the fourth lens E4 are aspherical surfaces. Table 12 shows the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32, A33, A34, A35, A36, A37, A38, A39, A40, A41, A42, A43, A44, A45, A46, A47, A48, A49, A50, A51, A52, A53, A54, A55, A56, A57, A58, A 10 , A 12 , A 14 , A 16 , A 18 , A 20 and A 22 .

[0162] Face number A4 A6 A8 A10 A12 S1 -1.4854E-03 2.7217E+00 -9.7057E+01 1.5020E+03 -1.2834E+04 S2 -2.1038E-01 9.0160E-01 -7.6459E+01 9.4545E+02 -6.7093E+03 S3 -4.2964E-01 -2.9929E+01 6.1390E+02 -7.9018E+03 6.1915E+04 S4 9.3597E-01 -2.7352E+01 2.5135E+02 -1.0985E+03 1.0065E+03 S5 2.8592E+00 -2.2381E+01 -1.4314E+02 3.4892E+03 -2.3971E+04 S6 3.3318E-01 -6.0829E+00 7.8135E+01 -6.1438E+02 2.8921E+03 S7 -3.8922E+00 8.5330E+00 -1.5904E+01 2.7314E+01 -3.8144E+01 S8 -4.7552E+00 1.4179E+01 -3.4818E+01 6.3523E+01 -8.2734E+01 Face number A14 A16 A18 A20 A22 S1 5.6063E+04 -9.9356E+04 0.0000E+00 0.0000E+00 0.0000E+00 S2 2.3509E+04 -2.8838E+04 -1.5517E+04 0.0000E+00 0.0000E+00 S3 -3.1008E+05 9.6769E+05 -1.6723E+06 1.1862E+06 0.0000E+00 S4 1.2330E+04 -6.0256E+04 1.1627E+05 -8.5063E+04 0.0000E+00 S5 8.5980E+04 -1.7545E+05 1.9376E+05 -9.0280E+04 0.0000E+00 S6 -7.5679E+03 1.0979E+04 -8.3339E+03 2.6008E+03 0.0000E+00 S7 3.7054E+01 -2.2475E+01 7.5745E+00 -1.0800E+00 0.0000E+00 S8 7.4996E+01 -4.5943E+01 1.8067E+01 -4.1068E+00 4.0992E-01

[0163] Table 12

[0164] Figure 8a The axial chromatic aberration curve of the optical imaging system of Example 4 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Figure 8b An astigmatism curve of the optical imaging system of Example 4 is shown, which represents the meridional field curvature and the sagittal field curvature. Figure 8c The distortion curve of the optical imaging system of Example 4 is shown, which represents the distortion magnitude values ​​corresponding to different image heights. Figure 8d The magnification chromatic aberration curve of the optical imaging system of Example 4 is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the lens. Figures 8a to 8d It can be seen from the figure that the optical imaging system provided in Example 4 can achieve good imaging quality. Specific embodiment 5

[0166] Fig. 9 Schematic diagram of the lens group structure of embodiment 5 of the optical imaging system of the present invention. The optical imaging system includes, in order from the object side to the image side along the optical axis: an aperture STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a filter E5 and an imaging surface S11.

[0167] The first lens E1 has positive power, its object side surface S1 is convex, and the image side surface S2 is concave. The second lens E2 has negative power, its object side surface S3 is concave, and the image side surface S4 is convex. The third lens E3 has positive power, its object side surface S5 is concave, and the image side surface S6 is convex. The fourth lens E4 has negative power, its object side surface S7 is convex, and the image side surface S8 is concave. The filter E5 has an object side surface S9 and an image side surface S10. The light from the object passes through each surface of surfaces S1 to S10 in sequence and is finally imaged on the imaging surface S11.

[0168] As shown in Table 13, it is a basic parameter table of the optical imaging system of Example 5, wherein the units of the radius of curvature, thickness, and focal length are all millimeters (mm).

[0169]

[0170] Table 13

[0171] As shown in Table 14, in Example 5, the total effective focal length f of the optical imaging system is 1.82 mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S11 of the optical imaging system is 2.39 mm, and half of the diagonal length of the effective pixel area on the imaging surface S11 is ImgH=1.88 mm. Half of the maximum field of view angle Semi-FOV of the optical imaging lens is 45.28°.

[0172]

[0173]

[0174] Table 14

[0175] In Example 5, the object side surface and the image side surface of any one of the first lens E1 to the fourth lens E4 are aspherical surfaces. Table 15 shows the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32, A33, A34, A35, A36, A37, A38, A39, A40, A41, A42, A43, A44, A45, A46, A47, A48, A49, A50, A51, A52, A53, A54, A55, A56, A57, A58, A 10 , A 12 , A 14 , A 16 , A 18 and A 20 .

[0176] Face number A4 A6 A8 A10 A12 S1 -1.0828E-01 1.2081E+01 -2.4792E+02 2.4197E+03 -7.2865E+03 S2 -9.2067E-02 -5.5141E-01 -2.0616E+01 3.2143E+02 -4.2326E+03 S3 -1.5671E+00 3.5553E+01 -1.4597E+03 3.0103E+04 -3.7694E+05 S4 1.2816E-01 -5.8000E+00 -8.6667E+01 2.2845E+03 -2.2648E+04 S5 7.0077E-01 7.1349E+00 -3.4199E+02 4.4844E+03 -2.8344E+04 S6 -2.1729E+00 1.5495E+01 -3.5008E+01 -2.9097E+02 2.8337E+03 S7 -5.3441E+00 2.0863E+01 -7.1646E+01 1.8877E+02 -3.4661E+02 S8 -4.5089E+00 1.4938E+01 -4.0208E+01 7.8782E+01 -1.0735E+02 Face number A14 A16 A18 A20 S1 -5.1881E+04 4.4749E+05 -9.4961E+05 0.0000E+00 S2 3.0705E+04 -1.1862E+05 1.7328E+05 0.0000E+00 S3 2.9171E+06 -1.3698E+07 3.5845E+07 -4.0120E+07 S4 1.2762E+05 -4.2742E+05 7.9026E+05 -6.1535E+05 S5 1.0143E+05 -2.1254E+05 2.4522E+05 -1.2102E+05 S6 -9.9550E+03 1.7525E+04 -1.5526E+04 5.5267E+03 S7 4.1838E+02 -3.1271E+02 1.3053E+02 -2.3224E+01 S8 9.7892E+01 -5.6637E+01 1.8702E+01 -2.6699E+00

[0177] Table 15

[0178] Fig.10a The axial chromatic aberration curve of the optical imaging system of Example 5 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Fig.10b An astigmatism curve of the optical imaging system of Example 5 is shown, which indicates meridional field curvature and sagittal field curvature. Fig.10c The distortion curve of the optical imaging system of Example 5 is shown, which represents the distortion magnitude values ​​corresponding to different image heights. Fig.10d The magnification chromatic aberration curve of the optical imaging system of Example 5 is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the lens. Figures 10a to 10d It can be seen from the figure that the optical imaging system provided in Example 5 can achieve good imaging quality. Specific embodiment 6

[0180] Fig.11 Schematic diagram of the lens group structure of embodiment 6 of the optical imaging system of the present invention. The optical imaging system includes, in order from the object side to the image side along the optical axis: an aperture STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a filter E5 and an imaging surface S11.

[0181] The first lens E1 has positive power, its object side surface S1 is convex, and the image side surface S2 is concave. The second lens E2 has negative power, its object side surface S3 is concave, and the image side surface S4 is convex. The third lens E3 has positive power, its object side surface S5 is concave, and the image side surface S6 is convex. The fourth lens E4 has negative power, its object side surface S7 is convex, and the image side surface S8 is concave. The filter E5 has an object side surface S9 and an image side surface S10. The light from the object passes through each surface of surfaces S1 to S10 in sequence and is finally imaged on the imaging surface S11.

[0182] As shown in Table 16, it is a basic parameter table of the optical imaging system of Example 6, wherein the units of the radius of curvature, thickness, and focal length are all millimeters (mm).

[0183]

[0184] Table 16

[0185] As shown in Table 17, in Example 6, the total effective focal length f of the optical imaging system is 1.81 mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S11 of the optical imaging system is 2.39 mm, and half of the diagonal length of the effective pixel area on the imaging surface S11 is ImgH=1.88 mm. Half of the maximum field of view angle Semi-FOV of the optical imaging lens is 45.30°.

[0186]

[0187] Table 17

[0188] In Example 6, the object side surface and the image side surface of any one of the first lens E1 to the fourth lens E4 are aspherical surfaces. Table 18 shows the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32, A33, A34, A35, A36, A37, A38, A39, A40, A41, A42, A43, A44, A45, A46, A47, A48, A49, A50, A51, A52, A53, A54, A55, A56, A57, A58, A 10 , A 12 , A 14 , A 16 , A 18 , A 20 , A 22 , A 24 and A 26 .

[0189]

[0190]

[0191] Table 18

[0192] Fig.12a The axial chromatic aberration curve of the optical imaging system of Example 6 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Figure 12b An astigmatism curve of the optical imaging system of Example 6 is shown, which indicates meridional field curvature and sagittal field curvature. Fig.12c The distortion curve of the optical imaging system of Example 6 is shown, which represents the distortion magnitude values ​​corresponding to different image heights. Fig.12d The magnification chromatic aberration curve of the optical imaging system of Example 6 is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the lens. Figures 12a to 12d It can be seen from the figure that the optical imaging system provided in Example 6 can achieve good imaging quality.

[0193] 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 optical imaging system, characterized in that: The optical imaging system has four lenses with optical power, and the four lenses include, in order from the object side to the image side along the optical axis: A first lens having positive refractive power, with a convex surface on the object side and a concave surface on the image side; a second lens having optical power; The third lens has positive refractive power, with a concave object side surface and a convex image side surface; The fourth lens element has a negative optical power and has a convex object side surface and a concave image side surface; The on-axis distance TTL from the object side of the first lens to the imaging plane and the distance BFL from the image side of the last lens of the optical imaging system to the imaging plane on the optical axis satisfy: 2.35≦TTL / BFL≦2.48; the minimum center thickness value CT2 of all lenses is the center thickness of the second lens on the optical axis; The curvature radius R5 of the object side surface of the third lens, the curvature radius R6 of the image side surface of the third lens, 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: 1.26≦|R6×R8| / |R5×R7|≦1.93; The effective focal length f of the optical imaging system and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 2.47≦f234 / f≦4.

45.

2. The optical imaging system according to claim 1, characterized in that: The maximum effective radius DT11 of the first lens object side surface and the maximum effective radius DT21 of the second lens object side surface satisfy: 0.86≦DT11 / DT21≦0.

95.

3. The optical imaging system according to claim 1, characterized in that: The effective focal length f, relative F number Fno and half of the maximum field of view Semi-FOV of the optical imaging system satisfy the following conditions: 3.48mm≦f×tan(Semi-FOV)×Fno≦4.17mm.

4. The optical imaging system according to claim 1, characterized in that: The center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, the center thickness CT3 of the third lens on the optical axis, the air interval T12 between the first lens and the second lens on the optical axis, and the air interval T34 between the third lens and the fourth lens on the optical axis satisfy: 1.41≦(CT1+CT2+T12) / (CT3+T34)≦2.

02.

5. The optical imaging system according to claim 1, characterized in that: The effective focal length f of the optical imaging system, the effective focal length f1 of the first lens, and the effective focal length f3 of the third lens satisfy: 0.23≦|(f3-f1) / f|≦2.

77.

6. The optical imaging system according to claim 1, characterized in that: The effective focal length f1 of the first lens and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 1.79≦f234 / f1≦3.

24.

7. The optical imaging system according to claim 1, characterized in that: The sum ΣAT of the air intervals on the optical axis between any two adjacent lenses with optical power from the first lens to the lens closest to the imaging surface and the sum ΣCT of the center thicknesses of all lenses on the optical axis satisfy: 2.2≦ΣCT / ΣAT≦3.

85.

8. The optical imaging system according to claim 1, characterized in that: An axial distance InTL from the object side of the first lens to the image side of the penultimate lens and an axial distance TTL from the object side of the first lens to the imaging plane satisfy: 2.06≦TTL / InTL≦2.

29.

9. The optical imaging system according to claim 1, characterized in that: The on-axis distance SAG41 between the intersection of the object side of the fourth lens and the optical axis to the effective radius vertex of the object side of the fourth lens, and the on-axis distance SAG32 between the intersection of the image side of the third lens and the optical axis to the effective radius vertex of the image side of the third lens satisfy: 1.11≦(SAG32+SAG41) / (SAG32-SAG41)≦4.

32.

10. The optical imaging system according to claim 1, characterized in that: The maximum value ETmax of the edge thicknesses of the first to fourth lenses and the edge thickness ET1 of the first lens satisfy the following: 1.22≦ETmax / ET1≦1.68.

Images