Optical image capturing system

Abstract

The invention provides an optical imaging system. The optical imaging system comprises a lens barrel, a lens group and a spacing element group, the lens group and the spacing element group are arranged in the lens barrel, the lens group is composed of four lenses, and the four lenses are sequentially a first lens with negative focal power, a second lens with focal power, a third lens with positive focal power and a fourth lens with positive focal power from an object side to an image side; the object side surface of the fourth lens is a convex surface; the spacing element group comprises a first spacing element, a second spacing element and a third spacing element; l / ImgH is greater than or equal to 2.21 and less than or equal to 2.90; f1 / f is greater than or equal to-2.13 and less than or equal to-1.51; (CT1 + T12) / EP01 is larger than or equal to 0.81 and smaller than or equal to 1.74. The problem that in the prior art, a four-piece optical imaging system controls the focal power of a front-end lens, the size of the front-end lens is easily designed improperly, and then the assembling stability is poor is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical imaging equipment, and in particular to an optical imaging system. Background Art

[0002] In the field of modern optical imaging technology, four-chip optical imaging systems are widely used in various imaging devices, such as mobile phone cameras, surveillance cameras, etc., due to their simple structure and low cost. However, with the development of technology and the improvement of user needs, the requirements for optical imaging systems are also increasing, especially in terms of imaging size and device miniaturization.

[0003] At present, the four-lens optical imaging system controls the focal length of the front lens on the basis of meeting the imaging size and miniaturization, thereby reasonably controlling the focusing ability of the front lens on the light, so as to control the light trend and ensure that the imaging requirements are met. However, in this case, it is easy to cause improper size design of the front lens, which makes the front lens prone to stress concentration during assembly, thereby affecting the assembly stability.

[0004] That is to say, the four-lens optical imaging system in the prior art has the problem of controlling the optical focal length of the front lens, which easily leads to improper design of the size of the front lens and thus causes poor assembly stability. Summary of the invention

[0005] The main purpose of the present invention is to provide an optical imaging system to solve the problem that the optical focal length of the front lens is controlled in the four-lens optical imaging system in the prior art, which easily causes improper design of the front lens size and leads to poor assembly stability.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present invention, an optical imaging system is provided, comprising a lens barrel, a lens group and a spacer element group arranged in the lens barrel, wherein the lens group is composed of four lenses, and the four lenses are, from the object side to the image side, a first lens with negative optical focal length, a second lens with optical focal length, a third lens with positive optical focal length and a fourth lens with positive optical focal length; the object side surface of the fourth lens is a convex surface; the spacer element group comprises a first spacer element located between the first lens and the second lens and partially supported by the image side surface of the first lens, a second spacer element located between the second lens and the third lens and partially supported by the image side surface of the second lens, a third spacer element located between the third lens and the fourth lens and partially supported by the image side surface of the third lens, and a fourth spacer element located between the third lens and the fourth lens and partially supported by the image side surface of the third lens. a third spacing element close to the lens; wherein, a spacing distance L from the object side surface of the lens barrel to the image side surface of the lens barrel on the optical axis of the optical imaging system and half of the diagonal length ImgH of the effective pixel area on the imaging plane of the optical imaging system satisfy: 2.21≤L / ImgH≤2.90; an effective focal length f1 of the first lens and an effective focal length f of the optical imaging system satisfy: -2.13≤f1 / f≤-1.51; a center thickness CT1 of the first lens on the optical axis, an air spacing T12 between the first lens and the second lens on the optical axis and a spacing distance EP01 from the object side surface of the lens barrel to the object side surface of the first spacing element on the optical axis satisfy: 0.81≤(CT1+T12) / EP01≤1.74.

[0007] According to another aspect of the present invention, an optical imaging system is also provided, comprising a lens barrel and a lens group and a spacer element group arranged in the lens barrel, wherein the lens group is composed of four lenses, and the four lenses are, from the object side to the image side, a first lens with negative optical focal length, a second lens with optical focal length, a third lens with positive optical focal length and a fourth lens with positive optical focal length; the image side surface of the first lens is a concave surface; the object side surface of the third lens is a concave surface, and the image side surface is a convex surface; the object side surface of the fourth lens is a convex surface; the spacer element group comprises a first spacer element located between the first lens and the second lens and partially supported by the image side surface of the first lens, a second spacer element located between the second lens and the third lens and partially supported by the image side surface of the second lens, and a A third spacing element is between the third lens and the fourth lens and partially supported by the image side surface of the third lens; wherein, the spacing distance L from the object side surface of the lens barrel to the image side surface of the lens barrel on the optical axis of the optical imaging system satisfies the following relationship with the effective focal length f of the optical imaging system: 1.74≤L / f≤3.15; the effective focal length f4 of the fourth lens, the curvature radius R5 of the object side surface of the third lens and the curvature radius R6 of the image side surface of the third lens satisfy the following relationship: -2.95≤f4 / (R5+R6)≤-0.60; the inner diameter d1s of the object side surface of the first spacing element, the outer diameter D0s of the object side surface of the lens barrel and the inner diameter d0s of the object side surface of the lens barrel satisfy the following relationship: 0.47≤d1s / (D0s-d0s)≤4.48.

[0008] According to another aspect of the present invention, an optical imaging system is also provided, comprising a lens barrel and a lens group and a spacer element group arranged in the lens barrel, wherein the lens group consists of four lenses, and the four lenses are, from the object side to the image side, a first lens with negative optical focal power, a second lens with optical focal power, a third lens with positive optical focal power and a fourth lens with positive optical focal power; the image side surface of the first lens is a concave surface; the object side surface of the third lens is a concave surface, and the image side surface is a convex surface; the object side surface of the fourth lens is a convex surface; the spacer element group comprises a first spacer element located between the first lens and the second lens and partially supported by the image side surface of the first lens, a second spacer element located between the second lens and the third lens and partially supported by the image side surface of the second lens, and a A third spacing element is provided between the third lens and the fourth lens and against the image side surface of the third lens; wherein, a spacing distance L from the object side surface of the lens barrel to the image side surface of the lens barrel on the optical axis of the optical imaging system satisfies the following relationship with half the diagonal length ImgH of an effective pixel area on an imaging surface of the optical imaging system: 2.21≤L / ImgH≤2.90; an effective focal length f1 of the first lens satisfies the following relationship with the effective focal length f of the optical imaging system: -2.13≤f1 / f≤-1.51; a curvature radius R1 of the object side surface of the first lens, a curvature radius R2 of the image side surface of the first lens and an inner diameter d1s of the object side surface of the first spacing element satisfy the following relationship with the following relationship: -4.91≤(R1+R2) / d1s≤1.87.

[0009] Further, the inner diameter d1s of the object side surface of the first spacing element, the outer diameter D0s of the object side surface of the lens barrel, and the inner diameter d0s of the object side surface of the lens barrel satisfy the following relationship: 0.47≤d1s / (D0s-d0s)≤4.48.

[0010] Furthermore, the object side surface of the third lens is concave, and the image side surface is convex; 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 and the inner diameter d3s of the object side surface of the third spacer element satisfy: -3.48≤(R5+R6) / d3s≤-0.87.

[0011] Further, the distance TD on the optical axis from the object side surface of the first lens to the image side surface of the fourth lens, the spacing distance EP12 on the optical axis from the image side surface of the first spacer element to the object side surface of the second spacer element, and the spacing distance EP23 on the optical axis from the image side surface of the second spacer element to the object side surface of the third spacer element satisfy: 2.35≤TD / (EP12+EP23)≤4.79.

[0012] Furthermore, the image side surface of the first lens is concave; the outer diameter D1s of the object side surface of the first spacing element, the inner diameter d1s of the object side surface of the first spacing element and the curvature radius R2 of the image side surface of the first lens satisfy: 1.45≤(D1s-d1s) / R2≤4.27.

[0013] Further, an inner diameter d3m of the image-side surface of the third spacing element and an inner diameter d2m of the image-side surface of the second spacing element satisfy the following relationship: 1.34≤d3m / d2m≤2.40.

[0014] Further, the spacing distance L from the object side surface of the lens barrel to the image side surface of the lens barrel on the optical axis, the sum ∑AT of the air gaps on the optical axis between two adjacent lenses among the first lens to the fourth lens, and the center thickness CT2 of the second lens on the optical axis satisfy: 3.55≤(L-∑AT) / CT2≤7.43.

[0015] Furthermore, an inner diameter d2s of the object-side surface of the second spacing element and an inner diameter d1m of the image-side surface of the first spacing element satisfy the following relationship: 0.49≤d2s / d1m≤1.87.

[0016] Furthermore, the spacer element group also includes a third auxiliary spacer element located between the third spacer element and the fourth lens and partially supported by the third spacer element, and the sum of the thicknesses ∑CP3 of all spacer elements between the third lens and the fourth lens, the center thickness CT3 of the third lens on the optical axis, the center thickness CT4 of the fourth lens on the optical axis and the air gap T34 between the third lens and the fourth lens on the optical axis satisfy: 0.43≤∑CP3 / (CT4+CT3+T34)≤0.91.

[0017] Furthermore, the spacer element group also includes a second auxiliary spacer element selectively arranged between the second spacer element and the third lens and partially supported by the second spacer element, and the sum of the thicknesses ∑CP2 of all spacer elements between the second lens and the third lens and the air space T23 between the second lens and the third lens on the optical axis satisfy: 0.08≤∑CP2 / T23≤1.52.

[0018] Furthermore, an outer diameter D3s of the object-side surface of the third spacing element, an inner diameter d3s of the object-side surface of the third spacing element, and an effective focal length f3 of the third lens satisfy the following relationship: 0.06≤(D3s-d3s) / f3≤1.70.

[0019] Furthermore, the spacer element group also includes a third auxiliary spacer element located between the third spacer element and the fourth lens and partially supported by the third spacer element, and the curvature radius R7 of the object side surface of the fourth lens and the inner diameter d3bm of the image side surface of the third auxiliary spacer element satisfy: 0.52≤R7 / d3bm≤2.40.

[0020] Furthermore, an inner diameter d0m of the image-side surface of the lens barrel and an effective focal length f4 of the fourth lens element satisfy: 0.58≤d0m / f4≤1.62.

[0021] Further, a center thickness CT2 of the second lens on the optical axis and a spacing distance EP12 from the image side surface of the first spacing element to the object side surface of the second spacing element on the optical axis satisfy: 0.66≤CT2 / EP12≤2.41.

[0022] Furthermore, the inner diameter d1m of the image side surface of the first spacer element, the curvature radius R3 of the object side surface of the second lens and the refractive index N2 of the second lens satisfy: -0.33≤d1m / R3 N2≤1.37.

[0023] By applying the technical solution of the present invention, the optical imaging system of the present application is composed of a lens barrel, four lenses arranged in the lens barrel, and a plurality of spacer elements. By reasonably arranging the optical focal length of each lens, the surface shape of the fourth lens, and the positions of the first spacer element to the third spacer element, and setting the optical imaging system to satisfy 2.21≤L / ImgH≤2.90 and -2.13≤f1 / f≤-1.51, it can be seen that by setting the optical focal length of the first lens to a negative value, if the thickness ratio of the first lens is improperly designed, it is easy for the first lens to experience stress concentration during assembly, resulting in greater assembly internal stress, thereby affecting the assembly stability of the optical imaging system. Therefore, the present application constrains 0.81≤(CT1+T12) / EP01≤1.74, and controls the ratio of the center thickness of the first lens on the optical axis, the sum of the air gaps between the first lens and the second lens on the optical axis, and the spacing distance from the object side of the lens barrel to the object side of the first spacing element on the optical axis within a certain range, which is conducive to reasonably controlling the center thickness and edge thickness of the first lens, facilitating the design of the structural dimensions of the first lens, reducing the assembly internal stress of the first lens and the front end of the lens barrel, avoiding the risk of deformation of the first lens during assembly, ensuring the assembly stability of the first lens, and further ensuring the assembly stability of the optical imaging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0025] Figure 1 A dimensioned diagram showing an optical imaging system according to an alternative embodiment of the present invention;

[0026] Figure 2 A schematic structural diagram of an optical imaging system according to Embodiment 1-1 of the present invention is shown;

[0027] Figure 3 A schematic structural diagram of an optical imaging system according to Embodiment 1-2 of the present invention is shown;

[0028] Figure 4A schematic diagram showing the structure of an optical imaging system according to embodiments 1 to 3 of the present invention is shown;

[0029] Figures 5 to 8 The magnification chromatic aberration curve, the axial chromatic aberration curve, the astigmatism curve and the distortion curve of the optical imaging system of the first embodiment of the present invention are respectively shown;

[0030] Fig. 9 A schematic structural diagram of an optical imaging system according to Embodiment 2-1 of the present invention is shown;

[0031] Fig.10 A schematic structural diagram of an optical imaging system according to Embodiment 2-2 of the present invention is shown;

[0032] Fig.11 A schematic structural diagram of an optical imaging system according to Embodiment 2-3 of the present invention is shown;

[0033] Figures 12 to 15 The magnification chromatic aberration curve, the axial chromatic aberration curve, the astigmatism curve and the distortion curve of the optical imaging system of the second embodiment of the present invention are respectively shown;

[0034] Fig.16 A schematic structural diagram of an optical imaging system according to Embodiment 3-1 of the present invention is shown;

[0035] Fig.17 A schematic structural diagram of an optical imaging system according to Embodiment 3-2 of the present invention is shown;

[0036] Fig.18 A schematic structural diagram of an optical imaging system according to Embodiment 3-3 of the present invention is shown;

[0037] Figures 19 to 22 The magnification chromatic aberration curve, the axial chromatic aberration curve, the astigmatism curve and the distortion curve of the optical imaging system of the third embodiment of the present invention are respectively shown;

[0038] Fig.23 An assembly stress diagram is shown when the optical imaging system of an optional example 1 of the present invention satisfies 2.21≤L / ImgH≤2.90, -2.13≤f1 / f≤-1.51 and (CT1+T12) / EP01=1.00;

[0039] Fig.24 An assembly stress diagram is shown when the optical imaging system of an optional example 2 of the present invention satisfies 2.21≤L / ImgH≤2.90, -2.13≤f1 / f≤-1.51 and (CT1+T12) / EP01=1.48;

[0040] Fig.25An assembly stress diagram is shown for the optical imaging system of Example 3 when 2.21≤L / ImgH≤2.90, -2.13≤f1 / f≤-1.51, and (CT1+T12) / EP01=1.90 is satisfied;

[0041] Fig.26 An assembly stress diagram is shown when the optical imaging system of Example 4 satisfies 2.21≤L / ImgH≤2.90, -2.13≤f1 / f≤-1.51, and (CT1+T12) / EP01=0.50.

[0042] The above drawings include the following reference numerals:

[0043] P0, lens barrel; E1, first lens; S1, object-side surface of the first lens; S2, image-side surface of the first lens; E2, second lens; S3, object-side surface of the second lens; S4, image-side surface of the second lens; E3, third lens; S5, object-side surface of the third lens; S6, image-side surface of the third lens; E4, fourth lens; S7, object-side surface of the fourth lens; S8, image-side surface of the fourth lens; P1, first spacer element; P2, second spacer element; P2b, second auxiliary spacer element; P3, third spacer element; P3b, third auxiliary spacer element. DETAILED DESCRIPTION

[0044] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0045] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0046] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity directions; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above-mentioned directional words are not used to limit the present invention.

[0047] 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 application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0048] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of illustration. 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 for illustration only and are not drawn strictly to scale.

[0049] In this article, the paraxial area refers to the area 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 area; 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 area. The judgment of the surface shape in the paraxial area can be based on the judgment method of the general knowledge in this field, and the positive and negative R value (R refers to the radius of curvature of the paraxial area, usually refers to the R value on the lens database (lens data) in the optical software) is used to judge the concave and convex. For the object side, when the R value is positive, it is judged as a convex surface, and when the R value is negative, it is judged as a concave surface; for the image side, when the R value is positive, it is judged as a concave surface, and when the R value is negative, it is judged as a convex surface. In this application, the left side is the object side and the right side is the image side.

[0050] In order to solve the problem in the prior art that the optical focal length of the front-end lens is controlled in a four-lens optical imaging system, which easily causes improper design of the size of the front-end lens and further leads to poor assembly stability, the present invention provides an optical imaging system.

[0051] like Figures 1 to 26As shown, in an optional embodiment of the present application, the optical imaging system includes a lens barrel and a lens group and a spacer element group arranged in the lens barrel, the lens group is composed of four lenses, and the four lenses are, from the object side to the image side, a first lens with negative optical focal length, a second lens with optical focal length, a third lens with positive optical focal length and a fourth lens with positive optical focal length; the object side surface of the fourth lens is a convex surface; the spacer element group includes a first spacer element located between the first lens and the second lens and partially supported by the image side surface of the first lens, a second spacer element located between the second lens and the third lens and partially supported by the image side surface of the second lens, and a third spacer element located between the third lens and the fourth lens and partially supported by the image side surface of the third lens. Three spacer elements; wherein, the spacing distance L from the object side surface of the lens barrel to the image side surface of the lens barrel on the optical axis of the optical imaging system and half of the diagonal length ImgH of the effective pixel area on the imaging surface of the optical imaging system satisfy: 2.21≤L / ImgH≤2.90; the effective focal length f1 of the first lens and the effective focal length f of the optical imaging system satisfy: -2.13≤f1 / f≤-1.51; the center thickness CT1 of the first lens on the optical axis, the air spacing T12 between the first lens and the second lens on the optical axis and the spacing distance EP01 from the object side surface of the lens barrel to the object side surface of the first spacer element on the optical axis satisfy: 0.81≤(CT1+T12) / EP01≤1.74.

[0052] The optical imaging system of the present application is composed of a lens barrel, four lenses arranged in the lens barrel, and a plurality of spacer elements. By reasonably arranging the optical focal length of each lens, the surface shape of the fourth lens, and the positions of the first spacer element to the third spacer element, and setting the optical imaging system to satisfy 2.21≤L / ImgH≤2.90 and -2.13≤f1 / f≤-1.51, it can be seen that by setting the optical focal length of the first lens to a negative value, if the thickness ratio of the first lens is improperly designed, it is easy for the first lens to experience stress concentration during assembly, resulting in greater assembly internal stress, thereby affecting the assembly stability of the optical imaging system. Therefore, the present application constrains 0.81≤(CT1+T12) / EP01≤1.74, and controls the ratio of the center thickness of the first lens on the optical axis, the sum of the air gaps between the first lens and the second lens on the optical axis, and the spacing distance from the object side of the lens barrel to the object side of the first spacing element on the optical axis within a certain range, which is conducive to reasonably controlling the center thickness and edge thickness of the first lens, facilitating the design of the structural dimensions of the first lens, reducing the assembly internal stress of the first lens and the front end of the lens barrel, avoiding the risk of deformation of the first lens during assembly, ensuring the assembly stability of the first lens, and further ensuring the assembly stability of the optical imaging system.

[0053] In addition, refer to the following table 1, Figure 23 to Figure 26As shown, under the premise that the optical imaging system satisfies 2.21≤L / ImgH≤2.90 and -2.13≤f1 / f≤-1.51, for example, L / ImgH=2.88, f1 / f=-1.98, or L / ImgH=2.32, f1 / f=-2.13. Fig.23 An assembly stress diagram is shown when the optical imaging system of optional example 1 of the present application satisfies (CT1+T12) / EP01=1.00. Fig.24 An assembly stress diagram is shown when the optical imaging system of optional example 2 of the present application satisfies (CT1+T12) / EP01=1.48. Fig.25 An assembly stress diagram is shown for the optical imaging system of Example 3 when (CT1+T12) / EP01=1.90 is satisfied. Fig.26 An assembly stress diagram is shown for the optical imaging system of Example 4 when (CT1+T12) / EP01=0.50 is satisfied. Figure 23 to Figure 26 In the figure, the upper side is the object side and the lower side is the image side.

[0054] Depend on Figure 23 to Figure 26 It can be seen that when (CT1+T12) / EP01=1.00 or (CT1+T12) / EP01=1.48 is satisfied, the assembly stress of the structure of the first lens and the object side end of the lens barrel is small. Fig.23 In the optical imaging system, the maximum and minimum values ​​of the assembly stress are 78.624MPa and 0.020097MPa respectively; Fig.24 In the figure, the maximum and minimum values ​​of the assembly stress in the optical imaging system are 66.881MPa and 0.031016MPa respectively; Fig.23 and Fig.24 It can be seen that the assembly stability of the optical imaging system is good. When (CT1+T12) / EP01=1.90 is satisfied, a large internal stress will occur at the edge flange position of the first lens, which will make the flange surface position of the first lens easily crushed by the assembly nozzle during the assembly process. At this time, the maximum and minimum values ​​of the assembly stress in the optical imaging system are 101.61MPa and 0.5656MPa, respectively, and the assembly stability is poor. When (CT1+T12) / EP01=0.50 is satisfied, the object side end structure of the lens barrel is affected by the extrusion of the first lens, and the object side end structure of the lens barrel will have a large internal stress, which is easy to cause the object side end structure of the lens barrel and the bearing surface of the first lens to deform, affecting the flatness of the bearing surface bearing on the first lens, thereby affecting the assembly stability of the first lens. At this time, the maximum and minimum values ​​of the assembly stress in the optical imaging system are 99.852MPa and 0.46327MPa, respectively, and the assembly stability is poor.

[0055] It can be seen that under the premise of satisfying 2.21≤L / ImgH≤2.90 and -2.13≤f1 / f≤-1.51 and controlling (CT1+T12) / EP01 within the range of 0.81 to 1.74, the assembly stress between the first lens and the lens barrel is the smallest, the assembly stress in the optical imaging system is the smallest, the assembly is the best, and the overall assembly stability is the best. Therefore, the present application controls the center thickness and edge thickness of the first lens reasonably by constraining 0.81≤(CT1+T12) / EP01≤1.74, by controlling the ratio of the center thickness of the first lens on the optical axis, the sum of the air spacing between the first lens and the second lens on the optical axis, and the spacing distance from the object side of the lens barrel to the object side of the first spacing element on the optical axis within a certain range, which is conducive to the reasonable design of the structure of the first lens, reduces the assembly internal stress of the first lens and the front end of the lens barrel, avoids the risk of deformation of the first lens during assembly, ensures the assembly stability of the first lens, and then ensures the assembly stability of the optical imaging system.

[0056] Table 1

[0057]

[0058] In this embodiment, the inner diameter d1s of the object side surface of the first spacing element, the outer diameter D0s of the object side surface of the lens barrel, and the inner diameter d0s of the object side surface of the lens barrel satisfy the following relationship: 0.47≤d1s / (D0s-d0s)≤4.48. This expression ensures the supporting width of the structure at the object side end of the lens barrel, prevents a large supporting misalignment between the structure at the object side end of the lens barrel and the edge flange position of the first lens during the assembly process, avoids affecting the assembly stability of the first lens, and ensures the overall assembly stability of the optical imaging system; at the same time, limiting d1s ensures that the reflected stray light of the first lens can be intercepted by the first spacing element, which is beneficial to improving the reflected stray light of the first lens.

[0059] In this embodiment, the object side surface of the third lens is concave, and the image side surface is convex; 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, and the inner diameter d3s of the object side surface of the third spacing element satisfy: -3.48≤(R5+R6) / d3s≤-0.87. By controlling the surface shape of the third lens and the expression, it is ensured that the shape of the third lens is more reasonable, the refraction effect of the third lens on the light is ensured, and the accurate transmission of the light in the third lens is ensured, and at the same time, it is ensured that the reflected stray light generated by the flange position of the object side surface of the third lens can be intercepted by the third spacing element, thereby improving the effect of stray light, and further ensuring the imaging quality of the optical imaging system.

[0060] In this embodiment, the distance TD on the optical axis from the object side of the first lens to the image side of the fourth lens, the distance EP12 on the optical axis from the image side of the first spacer element to the object side of the second spacer element, and the distance EP23 on the optical axis from the image side of the second spacer element to the object side of the third spacer element satisfy: 2.35≤TD / (EP12+EP23)≤4.79. Through this expression, the resolution performance of the optical imaging system is guaranteed by limiting TD, and the optical imaging system is guaranteed to present a clear image in each field of view. At the same time, the edge thickness of the second lens and the third lens is limited, the notch width of the second lens and the third lens is guaranteed, the molding problem of the second lens and the third lens is prevented, and the molding stability of the second lens and the third lens is guaranteed.

[0061] In this embodiment, the image side surface of the first lens is a concave surface; the outer diameter D1s of the object side surface of the first spacer element, the inner diameter d1s of the object side surface of the first spacer element, and the curvature radius R2 of the image side surface of the first lens satisfy: 1.45≤(D1s-d1s) / R2≤4.27. By controlling the difference between the outer diameter and the inner diameter of the object side surface of the first spacer element, it can be ensured that the first spacer element can effectively intercept the stray light at the edge of the effective diameter of the image side surface of the first lens; at the same time, by controlling the curvature radius of the image side surface of the first lens, the curvature degree of the image side surface of the first lens can be limited, ensuring the convergence trend of light.

[0062] In this embodiment, the inner diameter d3m of the image side surface of the third spacing element and the inner diameter d2m of the image side surface of the second spacing element satisfy: 1.34≤d3m / d2m≤2.40. Through this expression, the ratio of the inner diameter of the image side surface of the third spacing element to the inner diameter of the image side surface of the second spacing element is controlled to ensure the final imaging brightness of the optical imaging system, thereby meeting the specification requirements of the chip, thereby ensuring that a clear imaging image can be obtained in the end.

[0063] In this embodiment, the interval distance L between the object side surface of the lens barrel and the image side surface of the lens barrel on the optical axis, the sum of the air gaps ΣAT between two adjacent lenses of the first lens to the fourth lens on the optical axis, and the center thickness CT2 of the second lens on the optical axis satisfy: 3.55≤(L-ΣAT) / CT2≤7.43. By controlling the ratio of the difference between the maximum axial height of the lens barrel and the sum of the air gaps of all lenses to the center thickness of the second lens, that is, indirectly controlling the ratio of the sum of the center thicknesses of all lenses to the center thickness of the second lens, the purpose of controlling the position of the second lens in the entire optical imaging system is achieved, and the second lens can also be ensured to have good formability.

[0064] In this embodiment, the inner diameter d2s of the object side surface of the second spacer element and the inner diameter d1m of the image side surface of the first spacer element satisfy: 0.49≤d2s / d1m≤1.87. Through this expression, the inner diameter of the object side surface of the second spacer element and the inner diameter of the image side surface of the first spacer element are controlled, which is beneficial for the first spacer element and the second spacer element to intercept the stray light incident to the edge, ensure the improvement effect of the first spacer element and the second spacer element on the stray light of the optical imaging system, prevent the inner diameter surface of the spacer element from generating strong reflected stray light, and ensure the final imaging quality.

[0065] In this embodiment, the spacer element group further includes a third auxiliary spacer element located between the third spacer element and the fourth lens and partially supported by the third spacer element. The sum of the thickness of all the spacer elements between the third lens and the fourth lens ∑CP3, the center thickness CT3 of the third lens on the optical axis, the center thickness CT4 of the fourth lens on the optical axis, and the air gap T34 between the third lens and the fourth lens on the optical axis satisfy: 0.43≤∑CP3 / (CT4+CT3+T34)≤0.91. Through this expression, the sum of the thickness of all the spacer elements between the third lens and the fourth lens is controlled, the stray light improvement space between the third lens and the fourth lens is guaranteed, and at the same time, the reasonable distribution of the center thickness of the third lens and the fourth lens and the air gap is controlled, so that the change amount of the air gap of the optical imaging system during the assembly process can be limited, and the assembly yield rate can be guaranteed.

[0066] It should be noted here that ΣCP3 is the center thickness of the third spacer element on the optical axis, or is the sum of the center thickness of the third spacer element on the optical axis and the center thickness of the third auxiliary spacer element on the optical axis.

[0067] In this embodiment, the spacer element group further includes a second auxiliary spacer element selectively disposed between the second spacer element and the third lens and partially supported by the second spacer element, and the sum of the thickness of all the spacer elements between the second lens and the third lens ∑CP2 and the air interval T23 between the second lens and the third lens on the optical axis satisfy: 0.08≤∑CP2 / T23≤1.52. By controlling the ratio of the sum of the thickness of all the spacer elements between the second lens and the third lens to the air interval on the optical axis through this expression, it is possible to prevent the situation where the distance between the second lens and the third lens is too large so that the stray light between the lenses is reflected multiple times, so as to achieve the purpose of improving the stray light, thereby improving the final imaging quality.

[0068] It should be noted here that ΣCP2 is the center thickness of the second spacer element on the optical axis, or is the sum of the center thickness of the second spacer element on the optical axis and the center thickness of the second auxiliary spacer element on the optical axis.

[0069] In this embodiment, the outer diameter D3s of the object side surface of the third spacer element, the inner diameter d3s of the object side surface of the third spacer element and the effective focal length f3 of the third lens satisfy: 0.06≤(D3s-d3s) / f3≤1.70. By controlling the difference between the outer diameter and the inner diameter of the object side surface of the third spacer element, it is beneficial for the third spacer element to intercept excess stray light, thereby reducing the energy threshold of the final emitted stray light, and at the same time limiting the effective focal length of the third lens, which is beneficial to ensure the transmission path of the light.

[0070] In this embodiment, the curvature radius R7 of the object side surface of the fourth lens and the inner diameter d3bm of the image side surface of the third auxiliary spacer element satisfy: 0.52≤R7 / d3bm≤2.40. By limiting the ratio of the curvature radius of the object side surface of the fourth lens to the inner diameter of the image side surface of the third auxiliary spacer element within a certain range, it can be ensured that the third auxiliary spacer element can effectively block the stray light generated by the first three lenses, ensure the transmission stability of the imaging light entering the fourth lens, and thus ensure the final imaging quality of the lens.

[0071] In this embodiment, the inner diameter d0m of the image side surface of the lens barrel and the effective focal length f4 of the fourth lens satisfy: 0.58≤d0m / f4≤1.62. Through this expression, it is ensured that the outgoing light of the optical imaging system can converge at the imaging chip, and most of the light can be received by the imaging chip, thereby ensuring the imaging quality of the optical imaging system. At the same time, the inner diameter of the image side surface of the lens barrel is limited, ensuring that the size of the optical imaging system meets the image plane size of the imaging chip, and ensuring the adaptability of the optical imaging system.

[0072] In this embodiment, the center thickness CT2 of the second lens on the optical axis and the spacing distance EP12 from the image side surface of the first spacing element to the object side surface of the second spacing element on the optical axis satisfy: 0.66≤CT2 / EP12≤2.41. Through this expression, the center thickness and edge thickness of the second lens are limited, and the uniformity of the shape and size of the second lens is ensured, thereby ensuring the molding feasibility of the second lens.

[0073] In this embodiment, the inner diameter d1m of the image side surface of the first spacer element, the curvature radius R3 of the object side surface of the second lens and the refractive index N2 of the second lens satisfy: -0.33≤d1m / R3 N2≤1.37. By controlling the relationship between the inner diameter of the image side surface of the first spacer element, the radius of curvature of the object side surface of the second lens and the refractive index of the second lens, the curvature degree of the effective diameter of the object side surface of the second lens is guaranteed, and the mutual reflection between the effective diameter of the first spacer element and the first lens is prevented to generate optical ghost images with high energy, and at the same time, the first spacer element is guaranteed to intercept the excess stray light of the first lens.

[0074] In this embodiment, the image side surface of the first lens is concave; the object side surface of the third lens is concave, and the image side surface is convex. Reasonable planning of the lens surface shape is conducive to regulating the light trend, eliminating aberrations, and ensuring imaging quality.

[0075] Optionally, the optical imaging system in the embodiments of the present application can be simulated by software and / or tools such as ZEMAX, CODEV, etc. In the process of simulation using the above software and / or tools, the surface profile of each lens can be simulated and appropriately adjusted according to the surface profile of the software and / or tool used.

[0076] In addition, in another optional embodiment of the present application, an optical imaging system is also provided, including a lens barrel and a lens group and a spacer element group arranged in the lens barrel, the lens group is composed of four lenses, and the four lenses are, from the object side to the image side, a first lens with negative optical focal length, a second lens with optical focal length, a third lens with positive optical focal length and a fourth lens with positive optical focal length; the image side surface of the first lens is a concave surface; the object side surface of the third lens is a concave surface, and the image side surface is a convex surface; the object side surface of the fourth lens is a convex surface; the spacer element group includes a first spacer element located between the first lens and the second lens and partially supported by the image side surface of the first lens, a second spacer element located between the second lens and the third lens and partially supported by the image side surface of the second lens a third spacing element located between the third lens and the fourth lens and partially supported by the image side surface of the third lens; wherein, a spacing distance L from the object side surface of the lens barrel to the image side surface of the lens barrel on the optical axis of the optical imaging system and an effective focal length f of the optical imaging system satisfy: 1.74≤L / f≤3.15; an effective focal length f4 of the fourth lens, a curvature radius R5 of the object side surface of the third lens and a curvature radius R6 of the image side surface of the third lens satisfy: -2.95≤f4 / (R5+R6)≤-0.60; an inner diameter d1s of the object side surface of the first spacing element, an outer diameter D0s of the object side surface of the lens barrel and an inner diameter d0s of the object side surface of the lens barrel satisfy: 0.47≤d1s / (D0s-d0s)≤4.48.

[0077] The optical imaging system of the present application is composed of a lens barrel, four lenses arranged in the lens barrel, and a plurality of spacer elements. By reasonably arranging the optical focal length and surface shape of each lens, the positions of the first spacer element to the third spacer element, and setting the optical imaging system to satisfy 1.74≤L / f≤3.15 and -2.95≤f4 / (R5+R6)≤-0.60, it can be seen that under the condition of controlling the effective focal length of the fourth lens and the curvature radii of the object side and the image side of the third lens, if the first lens and the lens barrel are not supported reasonably, it is easy to cause the first lens and the lens barrel to be misaligned, thereby causing invalid light to be incident on the edge structure of the first lens and reflect to generate new stray light. Therefore, the present application ensures the supporting width of the structure at the object side end of the lens barrel by constraining 0.47≤d1s / (D0s-d0s)≤4.48, prevents a large supporting misalignment between the structure at the object side end of the lens barrel and the edge flange position of the first lens during the assembly process, limits d1s, ensures that the reflected stray light of the first lens can be intercepted by the first spacing element, and is beneficial to improving the reflected stray light of the first lens.

[0078] Of course, this embodiment may also include other parameter formulas in the above embodiment, which will not be described one by one here.

[0079] In addition, in another optional embodiment of the present application, an optical imaging system is also provided, including a lens barrel and a lens group and a spacer element group arranged in the lens barrel, the lens group is composed of four lenses, and the four lenses are, from the object side to the image side, a first lens with negative optical focal length, a second lens with optical focal length, a third lens with positive optical focal length and a fourth lens with positive optical focal length; the image side surface of the first lens is a concave surface; the object side surface of the third lens is a concave surface, and the image side surface is a convex surface; the object side surface of the fourth lens is a convex surface; the spacer element group includes a first spacer element located between the first lens and the second lens and partially supported by the image side surface of the first lens, and a second spacer element located between the second lens and the third lens and partially supported by the image side surface of the second lens , a third spacing element located between the third lens and the fourth lens and partially supported by the image side surface of the third lens; wherein, the spacing distance L from the object side surface of the lens barrel to the image side surface of the lens barrel on the optical axis of the optical imaging system and half of the diagonal length ImgH of the effective pixel area on the imaging surface of the optical imaging system satisfy: 2.21≤L / ImgH≤2.90; the effective focal length f1 of the first lens and the effective focal length f of the optical imaging system satisfy: -2.13≤f1 / f≤-1.51; the curvature radius R1 of the object side surface of the first lens, the curvature radius R2 of the image side surface of the first lens and the inner diameter d1s of the object side surface of the first spacing element satisfy: -4.91≤(R1+R2) / d1s≤1.87.

[0080] The optical imaging system of the present application is composed of a lens barrel, four lenses arranged in the lens barrel, and a plurality of spacer elements. By reasonably arranging the focal length and surface shape of each lens, the positions of the first spacer element to the third spacer element, and setting the optical imaging system to meet 2.21≤L / ImgH≤2.90 and -2.13≤f1 / f≤-1.51, it can be seen that when the focal length of the first lens is set to a negative value, if the surface shape of the first lens is unreasonable, it is difficult to control the deflection angle and divergence degree of the first lens to the incident light in front, and the large-angle light is easily reflected at the edge position of the first lens to form new stray light, affecting the clarity and contrast of the final image. Therefore, the present application, by constraining -4.91≤(R1+R2) / d1s≤1.87, on the one hand, ensures that the surface shape of the first lens is relatively reasonable, ensures the refraction effect of the first lens on the light, ensures the accurate transmission of the light in the first lens, and at the same time ensures that the stray light generated at the edge position of the first lens can be intercepted by the first spacer element, thereby ensuring the imaging quality of the optical imaging system.

[0081] Of course, this embodiment may also include other parameter formulas in the above embodiment, which will not be described one by one here.

[0082] Optionally, the optical imaging system may further include a protective glass for protecting the photosensitive element located on the imaging surface.

[0083] The optical imaging system in the present application may use multiple lenses, such as the four lenses mentioned above. In the present application, at least one of the mirror surfaces of each 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 using an aspherical lens, the aberration that occurs during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0084] 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 embodiments, the optical imaging system is not limited to including four lenses. If necessary, the optical imaging system may also include other numbers of lenses.

[0085] Figure 1 A dimension-marked schematic diagram of an optical imaging system of the present application is shown. Figure 1Parameters such as D0s, d0s, d2s, D1s, d1m, d1s, d3s, d3m, D3s, d3bm, d0m, ∑CP2, ∑CP3, L, EP01, EP12, EP23, etc. are marked in the figure to clearly and intuitively understand the meaning of the parameters. In order to facilitate the description of the optical imaging system and the surface shape of the specific lens, these parameters will no longer be reflected in the drawings when the specific embodiments are described later.

[0086] The following further describes examples of specific surface shapes and parameters of the optical imaging system applicable to the above-mentioned embodiments with reference to the accompanying drawings.

[0087] It should be noted that in the following embodiment 1, there are three examples of embodiment 1-1, embodiment 1-2, and embodiment 1-3; in embodiment 2, there are three examples of embodiment 2-1, embodiment 2-2, and embodiment 2-3; and in embodiment 3, there are three examples of embodiment 3-1, embodiment 3-2, and embodiment 3-3. In the three examples of the same embodiment, the parameters such as the radius of curvature, center thickness, and spacing distance between lenses of the optical imaging system from the first lens to the fourth lens, and the coefficients of high-order terms are the same, but the parameters such as the thickness, inner diameter, and outer diameter of the lens barrel, the first spacing element to the third spacing element are different. In other words, the main structure for imaging is the same, but the auxiliary structure for imaging is different.

[0088] It should be noted that any one of the following examples 1 to 3 is applicable to all implementation methods of the present application.

[0089] Embodiment 1

[0090] like Figures 2 to 8 As shown, the optical imaging system of embodiment 1 is described. Figure 2 shows a schematic structural diagram of the optical imaging system of Example 1-1, Figure 3 shows a schematic structural diagram of the optical imaging system of Embodiment 1-2, Figure 4 A schematic structural diagram of the optical imaging system of Embodiments 1-3 is shown.

[0091] like Figures 2 to 4 As shown, the optical imaging system includes a lens barrel P0 and a first lens E1, a first spacing element P1, a second lens E2, a second spacing element P2, a third lens E3, a third spacing element P3, a third auxiliary spacing element P3b, and a fourth lens E4, which are arranged in sequence in the lens barrel P0 from the object side to the image side along the optical axis.

[0092] like Figure 2As shown, it is a structural schematic diagram of the optical imaging system of Example 1-1. In this example, the image side of the second spacing element P2 is also provided with a second auxiliary spacing element P2b. The object side surface and image side surface of the first spacing element P1 are respectively supported by the image side surface S2 of the first lens and the object side surface S3 of the second lens. The object side surface and image side surface of the second spacing element P2 are respectively supported by the image side surface S4 of the second lens and the object side surface of the second auxiliary spacing element P2b, and the image side surface of the second auxiliary spacing element P2b is partially supported by the object side surface S5 of the third lens. The object side surface and image side surface of the third spacing element P3 are respectively supported by the image side surface S6 of the third lens and the object side surface of the third auxiliary spacing element P3b, and the image side surface of the third auxiliary spacing element P3b is partially supported by the object side surface S7 of the fourth lens.

[0093] like Figure 3 , which is a schematic diagram of the structure of the optical imaging system of Example 1-2. The difference between this example and Example 1-1 is that the second auxiliary spacer element P2b is not provided, so the object side surface and the image side surface of the second spacer element P2 are respectively supported by the image side surface S4 of the second lens and the object side surface S5 of the third lens. The supporting and abutting manner of the remaining spacer elements is the same as that of Example 1-1, and the relevant description in Example 1-1 can be referred to, and will not be repeated here.

[0094] like Figure 4 FIG. 1 is a schematic diagram of the structure of the optical imaging system of Example 1-3. In this example, the supporting and abutting manner of each spacing element is the same as that of Example 1-1, and the relevant description in Example 1-1 may be referred to, and will not be repeated here.

[0095] In summary, the structural parameters of the optical imaging system of Example 1 in Example 1-1, Example 1-2, and Example 1-3 are shown in Table 2 (unit: mm).

[0096] Table 2

[0097]

[0098] In the first embodiment, the object side surface S1 of the first lens is convex, and the image side surface S2 of the first lens is concave. The object side surface S3 of the second lens is concave, and the image side surface S4 of the second lens is convex. The object side surface S5 of the third lens is concave, and the image side surface S6 of the third lens is convex. The object side surface S7 of the fourth lens is convex, and the image side surface S8 of the fourth lens is concave.

[0099] In Example 1, half of the diagonal length ImgH of the effective pixel area on the imaging surface of the optical imaging system is 0.81 mm, the effective focal length f of the optical imaging system is 1.10 mm, the effective focal length f1 of the first lens is -2.18 mm, the effective focal length f2 of the second lens is 1.42 mm, the effective focal length f3 of the third lens is 7.04 mm, and the effective focal length f4 of the fourth lens is 3.17 mm.

[0100] Table 3 shows the basic structural parameters of the optical imaging system of Example 1, where the units of the radius of curvature and thickness / distance are all in millimeters. In the following table, OBJ (not shown in the figure) is the object distance. STO (not shown in the figure) is the aperture, which is located between the first lens E1 and the second lens E2. S9 and S10 (not shown in the figure) can be the object side and image side of the filter or the object side and image side of the protective glass. S11 (not shown in the figure) is the imaging surface.

[0101] Table 3

[0102]

[0103] In the first embodiment, the object side surface and the image side surface of the first lens E1 to the fourth lens E4 are all aspherical surfaces, and the surface shape of each aspherical lens can be defined by but not limited to the following aspherical surface formula:

[0104] Formula (1).

[0105] Wherein, x is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R, that is, the paraxial curvature c is the reciprocal of the curvature radius R in Table 3 above; k is the cone coefficient; Ai is the correction coefficient of the i-th order of the aspherical surface. Table 4 below gives the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each aspherical mirror surface S1-S8 in Example 1.

[0106] Table 4

[0107]

[0108] Figure 5 The magnification chromatic aberration curve of the optical imaging system of the first embodiment is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the optical imaging system. Figure 6 The axial chromatic aberration curve of the optical imaging system of the first embodiment is shown, which indicates the deviation of the focusing point of light rays of different wavelengths after passing through the imaging lens. Figure 7 The astigmatism curve of the optical imaging system of the first embodiment is shown, which represents the meridional image plane curvature and the sagittal image plane curvature. Figure 8The distortion curve of the optical imaging system of the first embodiment is shown, which indicates the distortion magnitude values ​​corresponding to different image heights.

[0109] according to Figures 5 to 8 It can be seen that the optical imaging system provided in the first embodiment can achieve good imaging quality.

[0110] Embodiment 2

[0111] like Figures 9 to 15 As shown, the optical imaging system of the second embodiment is described. Fig. 9 shows a schematic structural diagram of the optical imaging system of Example 2-1, Fig.10 shows a schematic structural diagram of the optical imaging system of Example 2-2, Fig.11 A schematic structural diagram of the optical imaging system of Example 2-3 is shown.

[0112] like Figures 9 to 11 As shown, the optical imaging system includes a lens barrel P0 and a first lens E1, a first spacing element P1, a second lens E2, a second spacing element P2, a third lens E3, a third spacing element P3, a third auxiliary spacing element P3b, and a fourth lens E4, which are arranged in sequence in the lens barrel P0 from the object side to the image side along the optical axis.

[0113] like Fig. 9 As shown, it is a structural schematic diagram of the optical imaging system of Example 2-1. In this example, the image side of the second spacing element P2 is also provided with a second auxiliary spacing element P2b. The object side surface and image side surface of the first spacing element P1 are respectively supported by the image side surface S2 of the first lens and the object side surface S3 of the second lens. The object side surface and image side surface of the second spacing element P2 are respectively supported by the image side surface S4 of the second lens and the object side surface of the second auxiliary spacing element P2b, and the image side surface of the second auxiliary spacing element P2b is partially supported by the object side surface S5 of the third lens. The object side surface and image side surface of the third spacing element P3 are respectively supported by the image side surface S6 of the third lens and the object side surface of the third auxiliary spacing element P3b, and the image side surface of the third auxiliary spacing element P3b is partially supported by the object side surface S7 of the fourth lens.

[0114] like Fig.10 , which is a schematic diagram of the structure of the optical imaging system of Example 2-2. The difference between this example and Example 2-1 is that the second auxiliary spacer element P2b is not provided, so the object side surface and the image side surface of the second spacer element P2 are respectively supported by the image side surface S4 of the second lens and the object side surface S5 of the third lens. The supporting and abutting manner of the remaining spacer elements is the same as that of Example 2-1, and the relevant description in Example 2-1 can be referred to, and will not be repeated here.

[0115] like Fig.11, which is a schematic diagram of the structure of the optical imaging system of Example 2-3. In this example, the supporting and abutting manner of each spacing element is the same as that of Example 2-1, and the relevant description in Example 2-1 may be referred to, and will not be repeated here.

[0116] In summary, the structural parameters of the optical imaging system of the second embodiment in Embodiment 2-1, Embodiment 2-2, and Embodiment 2-3 are shown in Table 5 (unit: mm).

[0117] Table 5

[0118]

[0119] In the second embodiment, the object side surface S1 of the first lens is a convex surface, and the image side surface S2 of the first lens is a concave surface. The object side surface S3 of the second lens is a convex surface, and the image side surface S4 of the second lens is a convex surface. The object side surface S5 of the third lens is a concave surface, and the image side surface S6 of the third lens is a convex surface. The object side surface S7 of the fourth lens is a convex surface, and the image side surface S8 of the fourth lens is a concave surface.

[0120] In Example 2, half of the diagonal length ImgH of the effective pixel area on the imaging surface of the optical imaging system is 0.81 mm, the effective focal length f of the optical imaging system is 1.13 mm, the effective focal length f1 of the first lens is -1.71 mm, the effective focal length f2 of the second lens is 1.19 mm, the effective focal length f3 of the third lens is 7.09 mm, and the effective focal length f4 of the fourth lens is 3.85 mm.

[0121] Table 6 shows the basic structural parameters of the optical imaging system of Example 2, where the units of the radius of curvature and thickness / distance are all in millimeters. In the following table, OBJ (not shown in the figure) is the object distance. STO (not shown in the figure) is the aperture, which is located between the first lens E1 and the second lens E2. S9 and S10 (not shown in the figure) can be the object side and image side of the filter or the object side and image side of the protective glass. S11 (not shown in the figure) is the imaging surface.

[0122] Table 6

[0123]

[0124] Table 7 below gives the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for the aspherical mirror surfaces S1-S8 in Example 2.

[0125] Table 7

[0126]

[0127] Fig.12The magnification chromatic aberration curve of the optical imaging system of the second embodiment is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the optical imaging system. Fig.13 The axial chromatic aberration curve of the optical imaging system of the second embodiment is shown, which indicates the deviation of the focal point of light of different wavelengths after passing through the imaging lens. Fig.14 The astigmatism curve of the optical imaging system of the second embodiment is shown, which represents the meridional image plane curvature and the sagittal image plane curvature. Fig.15 The distortion curve of the optical imaging system of the second embodiment is shown, which indicates the distortion magnitude values ​​corresponding to different image heights.

[0128] according to Figures 12 to 15 It can be seen that the optical imaging system provided in the second embodiment can achieve good imaging quality.

[0129] Embodiment 3

[0130] like Figures 16 to 22 As shown, the optical imaging system of embodiment 3 is described. Fig.16 A schematic diagram of the structure of the optical imaging system of Example 3-1 is shown, Fig.17 A schematic diagram of the structure of the optical imaging system of Example 3-2 is shown, Fig.18 A schematic structural diagram of the optical imaging system of Example 3-3 is shown.

[0131] like Figures 16 to 18 As shown, the optical imaging system includes a lens barrel P0 and a first lens E1, a first spacing element P1, a second lens E2, a second spacing element P2, a third lens E3, a third spacing element P3, a third auxiliary spacing element P3b, and a fourth lens E4, which are arranged in sequence in the lens barrel P0 from the object side to the image side along the optical axis.

[0132] like Fig.16 , which is a schematic diagram of the structure of the optical imaging system of Example 3-1. In this example, the object side surface and image side surface of the first spacing element P1 are partially supported by the image side surface S2 of the first lens and the object side surface S3 of the second lens, respectively. The object side surface and image side surface of the second spacing element P2 are partially supported by the image side surface S4 of the second lens and the object side surface S5 of the third lens, respectively. The object side surface and image side surface of the third spacing element P3 are partially supported by the image side surface S6 of the third lens and the object side surface of the third auxiliary spacing element P3b, respectively, and the image side surface of the third auxiliary spacing element P3b is partially supported by the object side surface S7 of the fourth lens.

[0133] like Fig.17 The structure diagram of the optical imaging system of Example 3-2 is shown in FIG. The supporting and abutting manner of each spacing element is the same as that of Example 3-1, and the relevant description in Example 3-1 may be referred to, and will not be repeated here.

[0134] like Fig.18 FIG. 3 is a schematic diagram of the structure of the optical imaging system of Example 3-3. In this example, the supporting and abutting manner of each spacing element is the same as that of Example 3-1, and the relevant description in Example 3-1 may be referred to, and will not be repeated here.

[0135] In summary, the structural parameters of the optical imaging system of Example 3 in Example 3-1, Example 3-2, and Example 3-3 are shown in Table 8 (unit: mm).

[0136] Table 8

[0137]

[0138] In the third embodiment, the object side surface S1 of the first lens is a concave surface, and the image side surface S2 of the first lens is a concave surface. The object side surface S3 of the second lens is a convex surface, and the image side surface S4 of the second lens is a concave surface. The object side surface S5 of the third lens is a concave surface, and the image side surface S6 of the third lens is a convex surface. The object side surface S7 of the fourth lens is a convex surface, and the image side surface S8 of the fourth lens is a convex surface.

[0139] In Example 3, half of the diagonal length ImgH of the effective pixel area on the imaging plane of the optical imaging system is 0.81 mm, the effective focal length f of the optical imaging system is 0.60 mm, the effective focal length f1 of the first lens is -1.28 mm, the effective focal length f2 of the second lens is -9.23 mm, the effective focal length f3 of the third lens is 0.96 mm, and the effective focal length f4 of the fourth lens is 1.77 mm.

[0140] Table 9 shows the basic structural parameter table of the optical imaging system of Example 3, where the units of the radius of curvature and thickness / distance are all in millimeters. In the following table, OBJ (not shown in the figure) is the object distance. STO (not shown in the figure) is the aperture, which is located between the first lens E1 and the second lens E2. S9 and S10 (not shown in the figure) can be the object side and image side of the filter or the object side and image side of the protective glass. S11 (not shown in the figure) is the imaging surface.

[0141] Table 9

[0142]

[0143] Table 10 below gives the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for the aspheric mirror surfaces S1-S8 in Example 3.

[0144] Table 10

[0145]

[0146] Fig.19The magnification chromatic aberration curve of the optical imaging system of the third embodiment is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the optical imaging system. Fig. 20 The axial chromatic aberration curve of the optical imaging system of the third embodiment is shown, which indicates the deviation of the focusing point of light of different wavelengths after passing through the imaging lens. Fig.21 The astigmatism curve of the optical imaging system of the third embodiment is shown, which represents the meridional image plane curvature and the sagittal image plane curvature. Fig. 22 The distortion curve of the optical imaging system of the third embodiment is shown, which indicates the distortion magnitude values ​​corresponding to different image heights.

[0147] according to Figures 19 to 22 It can be seen that the optical imaging system provided in the third embodiment can achieve good imaging quality.

[0148] In summary, Embodiment 1 to Embodiment 3 respectively satisfy the relationship shown in Table 11.

[0149] Table 11

[0150]

[0151] Table 12 shows half of the diagonal length ImgH of the effective pixel area on the imaging surface of the optical imaging system of Examples 1 to 3, the effective focal length f of the optical imaging system, and the effective focal length of each lens of the optical imaging system.

[0152] Table 12

[0153]

[0154] The present application also provides an imaging device, whose electronic photosensitive element can be a photosensitive coupled device (CCD) or a complementary metal oxide semiconductor element (CMOS). The imaging device can be an independent imaging device such as a digital camera, or an imaging module integrated in a mobile electronic device such as a mobile phone. The imaging device is equipped with the optical imaging system described above.

[0155] Specifically, the optical imaging system of the present application can be applied in an eye tracking system and used as an infrared lens, that is, the working band of the optical imaging system of the present application can be an infrared band. The optical imaging system of the present application has good optical performance stability, so that eye movement signals can be captured quickly.

[0156] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0157] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0158] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0159] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An optical imaging system, characterized in that: The invention comprises a lens barrel and a lens group and a spacer element group arranged in the lens barrel, The lens group is composed of four lenses, and the four lenses are, from the object side to the image side, a first lens with negative optical power, a second lens with optical power, a third lens with positive optical power, and a fourth lens with positive optical power; the object side surface of the fourth lens is a convex surface; The spacer element group includes a first spacer element located between the first lens and the second lens and partially supported by the image side surface of the first lens, a second spacer element located between the second lens and the third lens and partially supported by the image side surface of the second lens, and a third spacer element located between the third lens and the fourth lens and partially supported by the image side surface of the third lens; Wherein, the interval distance L between the object side surface of the lens barrel and the image side surface of the lens barrel on the optical axis of the optical imaging system and half of the diagonal length ImgH of the effective pixel area on the imaging surface of the optical imaging system satisfy: 2.21≤L / ImgH≤2.90; the effective focal length f1 of the first lens and the effective focal length f of the optical imaging system satisfy: -2.13≤f1 / f≤-1.51; The center thickness CT1 of the first lens on the optical axis, the air gap T12 between the first lens and the second lens on the optical axis, and the spacing distance EP01 from the object side surface of the lens barrel to the object side surface of the first spacing element on the optical axis satisfy the following: 0.81≤(CT1+T12) / EP01≤1.

74.

2. The optical imaging system according to claim 1, characterized in that: The inner diameter d1s of the object side surface of the first spacing element, the outer diameter D0s of the object side surface of the lens barrel, and the inner diameter d0s of the object side surface of the lens barrel satisfy the following relationship: 0.47≤d1s / (D0s-d0s)≤4.

48.

3. The optical imaging system according to claim 1, characterized in that: The object side surface of the third lens is concave, and the image side surface is convex; 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 and the inner diameter d3s of the object side surface of the third spacer element satisfy: -3.48≤(R5+R6) / d3s≤-0.

87.

4. The optical imaging system according to claim 1, characterized in that: The distance TD from the object side surface of the first lens to the image side surface of the fourth lens on the optical axis, the spacing distance EP12 from the image side surface of the first spacer element to the object side surface of the second spacer element on the optical axis, and the spacing distance EP23 from the image side surface of the second spacer element to the object side surface of the third spacer element on the optical axis satisfy the following: 2.35≤TD / (EP12+EP23)≤4.

79.

5. The optical imaging system according to claim 1, characterized in that: The image side surface of the first lens is a concave surface; the outer diameter D1s of the object side surface of the first spacer element, the inner diameter d1s of the object side surface of the first spacer element and the curvature radius R2 of the image side surface of the first lens satisfy: 1.45≤(D1s-d1s) / R2≤4.

27.

6. The optical imaging system according to claim 1, characterized in that: An inner diameter d3m of the image-side surface of the third spacing element and an inner diameter d2m of the image-side surface of the second spacing element satisfy the following relationship: 1.34≤d3m / d2m≤2.

40.

7. The optical imaging system according to claim 1, characterized in that: The spacing distance L from the object side surface of the lens barrel to the image side surface of the lens barrel on the optical axis, the sum ∑AT of the air gaps between two adjacent lenses of the first lens to the fourth lens on the optical axis, and the center thickness CT2 of the second lens on the optical axis satisfy the following: 3.55≤(L-∑AT) / CT2≤7.

43.

8. The optical imaging system according to claim 1, characterized in that: An inner diameter d2s of the object-side surface of the second spacing element and an inner diameter d1m of the image-side surface of the first spacing element satisfy the following relationship: 0.49≤d2s / d1m≤1.

87.

9. The optical imaging system according to claim 1, characterized in that: The spacer element group further includes a third auxiliary spacer element located between the third spacer element and the fourth lens and partially supported by the third spacer element. The sum of the thicknesses ∑CP3 of all spacing elements between the third lens and the fourth lens, the center thickness CT3 of the third lens on the optical axis, the center thickness CT4 of the fourth lens on the optical axis, and the air gap T34 between the third lens and the fourth lens on the optical axis satisfy: 0.43≤∑CP3 / (CT4+CT3+T34)≤0.

91.

10. The optical imaging system according to claim 1, characterized in that: The spacer element group further includes a second auxiliary spacer element selectively disposed between the second spacer element and the third lens and partially supported by the second spacer element. A sum ΣCP2 of thicknesses of all spacing elements between the second lens and the third lens and an air interval T23 between the second lens and the third lens on the optical axis satisfy: 0.08≤ΣCP2 / T23≤1.

52.

11. The optical imaging system according to claim 1, characterized in that: An outer diameter D3s of the object side surface of the third spacing element, an inner diameter d3s of the object side surface of the third spacing element, and an effective focal length f3 of the third lens satisfy the following: 0.06≤(D3s-d3s) / f3≤1.

70.

12. The optical imaging system according to claim 1, characterized in that: The spacer element group also includes a third auxiliary spacer element located between the third spacer element and the fourth lens and partially supported by the third spacer element. The curvature radius R7 of the object side surface of the fourth lens and the inner diameter d3bm of the image side surface of the third auxiliary spacer element satisfy the following: 0.52≤R7 / d3bm≤2.

40.

13. The optical imaging system according to claim 1, characterized in that: The inner diameter d0m of the image side surface of the lens barrel and the effective focal length f4 of the fourth lens satisfy the following: 0.58≤d0m / f4≤1.

62.

14. The optical imaging system according to claim 1, characterized in that: A center thickness CT2 of the second lens on the optical axis and a spacing distance EP12 from the image side surface of the first spacing element to the object side surface of the second spacing element on the optical axis satisfy the following: 0.66≤CT2 / EP12≤2.

41.

15. The optical imaging system according to claim 1, characterized in that: The inner diameter d1m of the image-side surface of the first spacer element, the curvature radius R3 of the object-side surface of the second lens and the refractive index N2 of the second lens satisfy: .

Images