Optical imaging system

Abstract

The application provides an optical imaging system, comprising: a first lens to a fourth lens, the first lens has positive refractive power, the second lens has negative refractive power, the third lens has positive refractive power, and the fourth lens has positive refractive power; a spacer element group, the spacer element group at least comprises a third spacer element located between the third lens and the fourth lens and at least partially abutting with an image side surface of the third lens; a lens barrel; the effective focal length f3 of the third lens, the effective focal length f of the optical imaging system satisfy: 0 < f3 / f < 1.7; the curvature radius R5 of the object side surface of the third lens, the inner diameter d3s of the object side surface of the third spacer element and the refractive index N3 of the third lens satisfy: 1 < R5 / d3s*N3 < 3.5. The application solves the problem of serious stray light in the prior art optical imaging system.

Description

Technical Field

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

[0002] With the continuous improvement of the imaging quality requirements of mobile phone cameras by users, a single imaging module can no longer meet the needs of users. Currently, smart phone devices are equipped with multiple optical imaging systems to meet different usage environments of users. Among them, the telephoto optical imaging system has a relatively large aperture. Especially at the rear end of the optical imaging system, stray light is likely to enter the imaging surface, affecting the imaging clarity. Therefore, how to control the optical parameters of the rear lens of the optical imaging system and the inner diameter size of the spacer element, while ensuring stable assembly and reducing stray light to improve image quality, is a very important issue. Summary of the Invention

[0003] The main object of the present invention is to provide an optical imaging system to solve the problem of severe stray light in the existing optical imaging system.

[0004] To achieve the above object, according to one aspect of the present invention, there is provided an optical imaging system, including: a lens group, sequentially including a first lens to a fourth lens from the object side to the image side of the optical imaging system, the first lens having a positive optical power, the object side surface of the first lens being convex, the second lens having a negative optical power, the image side surface of the second lens being concave, the third lens having a positive optical power, the object side surface of the third lens being convex, the image side surface of the third lens being concave, the fourth lens having a positive optical power, the object side surface of the fourth lens being convex, and the image side surface of the fourth lens being concave; a spacer element group, the spacer element group at least including a third spacer element located between the third lens and the fourth lens and at least partially abutted against the image side surface of the third lens; a lens barrel, the lens barrel being used to accommodate the lens group and the spacer element group; wherein, the effective focal length f3 of the third lens and the effective focal length f of the optical imaging system satisfy: 0 < f3 / f < 1.7; the radius of curvature R5 of the object side surface of the third lens, the inner diameter d3s of the object side surface of the third spacer element, and the refractive index N3 of the third lens satisfy: 1 < R5 / d3s*N3 < 3.5.

[0005] According to another aspect of the present invention, an optical imaging system is provided, comprising: a lens group, the lens group including a first lens to a fourth lens sequentially from the object side to the image side of the optical imaging system, wherein the first lens has positive optical power and the object side of the first lens is convex, the second lens has negative optical power and the image side of the second lens is concave, the third lens has positive optical power, the object side of the third lens is convex and the image side of the third lens is concave, the fourth lens has positive optical power, the object side of the fourth lens is convex and the image side of the fourth lens is concave; a spacer element group, the spacer element group including at least a second spacer element located between the second lens and the third lens and at least partially abutting against the image side of the second lens; a lens barrel for accommodating the lens group and the spacer element group; wherein the effective focal length f2 of the second lens, the outer diameter D2m of the image side of the second spacer element, and the inner diameter d2s of the object side of the second spacer element satisfy: -2.5 < f2 / (D2m-d2s) < 0. This application provides a four-lens optical imaging system. By rationally matching the optical power and surface shape of the four lenses, light is converged before entering the imaging front. However, there is a lot of stray light in the optical imaging system, which seriously affects the image cleanliness. This application can control the direction of light at the second lens by controlling the effective focal length of the second lens and the inner and outer diameters of the second spacer element. The inner diameter of the second spacer element can intercept stray light transmitted from the front and reflected back from the third lens to the maximum extent, ensuring the quality of the imaging light and improving the quality of the optical imaging system.

[0006] According to another aspect of the present invention, an optical imaging system is provided, including: a lens group, sequentially including a first lens to a fourth lens from the object side to the image side of the optical imaging system. The first lens has a positive optical power, the object side surface of the first lens is convex, the second lens has a negative optical power, the image side surface of the second lens is concave, the third lens has a positive optical power, the object side surface of the third lens is convex, the image side surface of the third lens is concave, the fourth lens has a positive optical power, the object side surface of the fourth lens is convex, and the image side surface of the fourth lens is concave; a spacer element group, the spacer element group at least includes a first spacer element located between the first lens and the second lens and at least partially abutting against the image side surface of the first lens, and a second spacer element located between the second lens and the third lens and at least partially abutting against the image side surface of the second lens; a lens barrel for accommodating the lens group and the spacer element group; wherein, the combined focal length f₁₂ of the first lens and the second lens, the inner diameter d₁ₛ of the object side surface of the first spacer element, and the inner diameter d₂ₛ of the object side surface of the second spacer element satisfy: -4 < f₁₂ / (d₁ₛ + d₂ₛ) < -1. This application provides a four-piece optical imaging system. Through the reasonable combination of the optical powers and surface types of the four lenses, the light is converged before entering the imaging surface, but there are many stray light rays in the optical imaging system, seriously affecting the imaging cleanliness. However, in this application, by controlling the combined focal length of the first lens and the second lens, and the inner diameter sizes of the first and second spacer elements, the trend of light rays at the first and second lenses can be controlled. The inner diameters of the first and second spacer elements can intercept the stray light rays transmitted forward and reflected back by the third lens to the maximum extent, ensuring the quality of the imaging light rays and improving the quality of the optical imaging system.

[0007] Further, the effective focal length f₄ of the fourth lens and the effective focal length f of the optical imaging system satisfy: 0.2 < f₄ / f < 1.6, and the outer diameter D₃ₘ of the image side surface of the third spacer element and the curvature radius R₇ of the object side surface of the fourth lens satisfy: 1.5 < D₃ₘ / R₇ < 3.5.

[0008] Further, the central thickness CT₄ of the fourth lens on the optical axis of the optical imaging system, the air gap T₃₄ between the third lens and the fourth lens on the optical axis, and the maximum thickness CP₃ of the third spacer element along the optical axis direction satisfy: 3 < CT₄ / (T₃₄ + CP₃) < 5.

[0009] Further, the spacer element group further includes a second spacer element located between the second lens and the third lens and at least partially abutting against the image side surface of the second lens. The distance EP₂₃ along the optical axis direction from the image side surface of the second spacer element to the object side surface of the third spacer element, the Abbe number V₂ of the second lens, the Abbe number V₃ of the third lens, and the effective focal length f₃ of the third lens satisfy: 2 < EP₂₃*(V₂ + V₃) / f₃ < 4.

[0010] Furthermore, the spacer element group also includes a second spacer element located between the second lens and the third lens and at least partially abutting the image-side surface of the second lens. The outer diameter D2s of the object-side surface of the second spacer element, the radius of curvature R3 of the object-side surface of the second lens, and the refractive index N2 of the second lens satisfy the following relationship: -4 <D2s / R3*N2<1。

[0011] Furthermore, the spacer element group also includes a second spacer element located between the second lens and the third lens and at least partially abutting the image side of the second lens. The effective focal length f2 of the second lens, the outer diameter D2m of the image side of the second spacer element, and the inner diameter d2s of the object side of the second spacer element satisfy the following: -2.5 < f2 / (D2m-d2s) < 0.

[0012] Furthermore, the spacer element group also includes a first spacer element located between the first lens and the second lens and at least partially abutting the image-side surface of the first lens, and a second spacer element located between the second lens and the third lens and at least partially abutting the image-side surface of the second lens. The combined focal length f12 of the first lens and the second lens, the inner diameter d1s of the object-side surface of the first spacer element, and the inner diameter d2s of the object-side surface of the second spacer element satisfy the following: -4 <f12 / (d1s+d2s)<-1。

[0013] Furthermore, the inner diameter d0s of the object-side end face of the microscope tube and the entrance pupil diameter EPD of the optical imaging system satisfy the following relationship: 0.8 <d0s / EPD<1.8。

[0014] Furthermore, the spacer element group also includes a first spacer element located between the first lens and the second lens and at least partially abutting the image-side surface of the first lens, and a second spacer element located between the second lens and the third lens and at least partially abutting the image-side surface of the second lens. The distance EP23 between the image-side surface of the second spacer element and the object-side surface of the third spacer element along the optical axis of the optical imaging system, and the distance EP12 between the image-side surface of the first spacer element and the object-side surface of the second spacer element along the optical axis, satisfy the following condition: 0.8 <EP12 / EP23<3。

[0015] Furthermore, the spacer element group also includes a first spacer element located between the first lens and the second lens and at least partially abutting the image-side surface of the first lens. The outer diameter D1m of the image-side surface of the first spacer element and the radius of curvature R1 of the object-side surface of the first lens satisfy the following: 1 <D1m / R1<2.5。

[0016] Further, the spacer element group further includes a first spacer element located between the first lens and the second lens and at least partially abutting against the image side surface of the first lens, and a second spacer element located between the second lens and the third lens and at least partially abutting against the image side surface of the second lens. The distance EP12 from the image side surface of the first spacer element to the object side surface of the second spacer element along the optical axis direction of the optical imaging system and the axial distance SAG11 between the intersection of the object side surface of the first lens and the optical axis and the vertex of the effective radius of the object side surface of the first lens satisfy: 1 < EP12 / SAG11 < 2.

[0017] Further, the spacer element group further includes a first spacer element located between the first lens and the second lens and at least partially abutting against the image side surface of the first lens, and a first auxiliary spacer element located between the first spacer element and the second lens and at least partially abutting against the image side surface of the first spacer element. The outer diameter D1bm, the inner diameter d1bm of the image side surface of the first auxiliary spacer element, and the effective focal length f2 of the second lens satisfy: -5.5 < (D1bm + d1bm) / f2 < -2.

[0018] Further, the inner diameter d0m of the image side end surface of the lens barrel and the maximum effective radius DT42 of the image side surface of the fourth lens satisfy: 0 < d0m / DT42 < 5.

[0019] Applying the technical solution of the present invention, the optical imaging system includes a lens group, a spacer element group, and a lens barrel. The lens group sequentially includes the first lens to the fourth lens from the object side to the image side of the optical imaging system. The optical power of the first lens is positive, the object side surface of the first lens is convex, the optical power of the second lens is negative, the image side surface of the second lens is concave, the optical power of the third lens is positive, the object side surface of the third lens is convex, the image side surface of the third lens is concave, the optical power of the fourth lens is positive, the object side surface of the fourth lens is convex, and the image side surface of the fourth lens is concave; the spacer element group at least includes a third spacer element located between the third lens and the fourth lens and at least partially abutting against the image side surface of the third lens; the lens barrel is used to accommodate the lens group and the spacer element group; wherein, the effective focal length f3 of the third lens and the effective focal length f of the optical imaging system satisfy: 0 < f3 / f < 1.7; the radius of curvature R5 of the object side surface of the third lens, the inner diameter d3s of the object side surface of the third spacer element, and the refractive index N3 of the third lens satisfy: 1 < R5 / d3s * N3 < 3.5.

[0020] The present application provides a four-piece optical imaging system that satisfies 0 < f3 / f < 1.7 and 1 < R5 / d3s*N3 < 3.5. Through the reasonable combination of the optical powers and surface shapes of the four lenses, the light rays are converged before entering the imaging surface. However, there are较多 stray light rays at the rear end of the optical imaging system, seriously affecting the imaging cleanliness. In this application, by controlling the effective focal length, refractive index, curvature radius of the third lens, and the inner diameter size of the third spacer element, the trend of the light rays at the third lens can be controlled, the shape of the optical effective area and the structural part of the third lens can be adjusted, the internal reflection stray light of the structural part can be reduced, and at the same time, the inner diameter of the third spacer element can intercept stray light rays to the maximum extent, ensuring the quality of the imaging light rays and improving the quality of the optical imaging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0022] Figure 1 A partial parameter schematic diagram of the optical imaging system according to an optional embodiment of the present invention is shown;

[0023] Figure 2 A structural schematic diagram of the optical imaging system according to Embodiment 1 of the present invention is shown;

[0024] Figures 3 to 6 The axial chromatic aberration curve, astigmatism curve, distortion curve, and lateral chromatic aberration curve of Embodiment 1 of the present invention are respectively shown;

[0025] Figure 7 A structural schematic diagram of the optical imaging system according to Embodiment 2 of the present invention is shown;

[0026] Figure 8 A structural schematic diagram of the optical imaging system according to Embodiment 3 of the present invention is shown;

[0027] Figure 9 A structural schematic diagram of the optical imaging system according to Embodiment 4 of the present invention is shown;

[0028] Figures 10 to 13 The axial chromatic aberration curve, astigmatism curve, distortion curve, and lateral chromatic aberration curve of Embodiment 4 of the present invention are respectively shown;

[0029] Figure 14 A structural schematic diagram of the optical imaging system according to Embodiment 5 of the present invention is shown;

[0030] Figure 15 A structural schematic diagram of the optical imaging system according to Embodiment 6 of the present invention is shown;

[0031] Figure 16A schematic diagram of the optical imaging system according to Embodiment 7 of the present invention is shown;

[0032] Figures 17 to 20 The on-axis chromatic aberration curve, astigmatism curve, distortion curve, and magnification chromatic aberration curve of Embodiment 7 of the present invention are shown respectively.

[0033] Figure 21 A schematic diagram of the optical imaging system according to Embodiment 8 of the present invention is shown;

[0034] Figure 22 A schematic diagram of the optical imaging system according to Embodiment 9 of the present invention is shown;

[0035] Figure 23 The stray light energy diagram of an optical imaging system according to an optional embodiment of this application is shown under the conditions of f3 / f = 0.834 and R5 / d3s*N3 = 2.4.

[0036] Figure 24 The stray light energy diagram of an optical imaging system according to an optional embodiment of this application is shown under the conditions of f3 / f = 0.834 and R5 / d3s*N3 = 2.802.

[0037] Figure 25 The stray light energy diagram of the prior art optical imaging system is shown under the conditions of f3 / f = 0.834 and R5 / d3s*N3 = -8;

[0038] Figure 26 The stray light energy diagram of a prior art optical imaging system is shown under the conditions of f3 / f = 0.834 and R5 / d3s*N3 = 10.

[0039] The above figures include the following reference numerals:

[0040] E1, First lens; S1, Object-side surface of the first lens; S2, Image-side surface of the first lens; P1, First spacer element; P1b, First auxiliary spacer element; P1c, First auxiliary element; E2, Second lens; S3, Object-side surface of the second lens; S4, Image-side surface of the second lens; P2, Second spacer element; E3, Third lens; S5, Object-side surface of the third lens; S6, Image-side surface of the third lens; P3, Third spacer element; E4, Fourth lens; S7, Object-side surface of the fourth lens; S8, Image-side surface of the fourth lens. Detailed Implementation

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0043] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0044] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0045] In the accompanying 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 illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not drawn strictly to scale.

[0046] In this paper, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity 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 location of the concaveness 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 side is called the object-side surface of the lens, and the surface of each lens closest to the image side is called the image-side surface of the lens. The surface shape in the paraxial region can be determined according to the judgment method commonly used by those knowledgeable in the field, using the R value (R refers to the radius of curvature of the paraxial region, usually the R value in the lens database of optical software) to determine concavity or convexity. For the object-side surface, when the R value is positive, it is determined to be convex, and when the R value is negative, it is determined to be concave; for the image-side surface, when the R value is positive, it is determined to be concave, and when the R value is negative, it is determined to be convex.

[0047] To address the problem of severe stray light in existing optical imaging systems, this invention provides an optical imaging system.

[0048] First Implementation Method

[0049] like Figures 1 to 24As shown, the optical imaging system includes a lens group, a spacer element group, and a lens barrel. The lens group sequentially includes a first lens to a fourth lens from the object side to the image side of the optical imaging system. The first lens has a positive optical power, and the object side surface of the first lens is convex. The second lens has a negative optical power, and the image side surface of the second lens is concave. The third lens has a positive optical power, and the object side surface of the third lens is convex. The image side surface of the third lens is concave. The fourth lens has a positive optical power, and the object side surface of the fourth lens is convex. The image side surface of the fourth lens is concave. The spacer element group at least includes a third spacer element located between the third lens and the fourth lens and at least partially abutting against the image side surface of the third lens. The lens barrel is used to accommodate the lens group and the spacer element group. Among them, the effective focal length f3 of the third lens and the effective focal length f of the optical imaging system satisfy: 0 < f3 / f < 1.7. The radius of curvature R5 of the object side surface of the third lens, the inner diameter d3s of the object side surface of the third spacer element, and the refractive index N3 of the third lens satisfy: 1 < R5 / d3s * N3 < 3.5.

[0050] This application provides a four-lens optical imaging system that satisfies 0 < f3 / f < 1.7 and 1 < R5 / d3s * N3 < 3.5. Through the reasonable combination of the optical powers and surface types of the four lenses, the light is converged before entering the imaging surface, but there are more stray light rays at the rear end of the optical imaging system, seriously affecting the imaging cleanliness. However, in this application, by controlling the effective focal length, refractive index, radius of curvature of the third lens, and the inner diameter size of the third spacer element, the trend of the light rays at the third lens can be controlled, the shape of the optical effective area and the structural part of the third lens can be adjusted, and the internal reflected stray light of the structural part can be reduced. At the same time, the inner diameter of the third spacer element can intercept stray light rays to the maximum extent, ensuring the quality of the imaging light rays and improving the quality of the optical imaging system.

[0051] Preferably, 0.2 < f3 / f < 1.5.

[0052] Preferably, 1.2 < R5 / d3s * N3 < 3.3. <e

[0053] The following combines Figures 23 to 26 to further illustrate the role of the technical solution of this application in improving stray light. Figure 23 The stray light energy diagram of the optical imaging system of this application under the conditions of f3 / f = 0.834 and R5 / d3s * N3 = 2.4 is shown. Figure 24 The stray light energy diagram of the optical imaging system of this application under the conditions of f3 / f = 0.834 and R5 / d3s * N3 = 2.802 is shown. From Figure 23 and Figure 24 it can be seen that the stray light energy of the optical imaging system of this application is weak or even basically no stray light is generated. Figure 25The stray light energy diagram of an optical imaging system in the prior art under the conditions of f3 / f = 0.834 and R5 / d3s*N3 = -8 is shown. Figure 26 The stray light energy diagram of an optical imaging system in the prior art under the conditions of f3 / f = 0.834 and R5 / d3s*N3 = 10 is shown. From Figure 25 and Figure 26 it can be seen that the stray light energy of the optical imaging system is relatively strong, seriously affecting the imaging quality. By comparison Figures 23 to 26 it can be known that the technical solution of the present application can achieve a good stray light elimination effect and greatly improve the imaging quality by controlling 1 < R5 / d3s*N3 < 3.5. In this embodiment, the effective focal length f4 of the fourth lens and the effective focal length f of the optical imaging system satisfy: 0.2 < f4 / f < 1.6, and the outer diameter D3m of the image side surface of the third spacer element and the curvature radius R7 of the object side surface of the fourth lens satisfy: 1.5 < D3m / R7 < 3.5. By limiting f4 / f and D3m / R7 within a reasonable range, it is beneficial to reasonably distribute the effective focal length of the fourth lens and ensure the size of the fourth lens at the same time, which is beneficial to the processing and forming of the fourth lens. Preferably, 0.2 < f4 / f < 1.6 and 1.7 < D3m / R7 < 3.3.

[0054] In this embodiment, the central thickness CT4 of the fourth lens on the optical axis of the optical imaging system, the air gap T34 between the third lens and the fourth lens on the optical axis, and the maximum thickness CP3 of the third spacer element along the optical axis direction satisfy: 3 < CT4 / (T34 + CP3) < 5. By limiting CT4 / (T34 + CP3) within a reasonable range, it is beneficial to configure the distance and size between the lenses. For the air gap between the third lens and the fourth lens on the optical axis and the thickness of the third spacer element, the thickness of the fourth lens can be reasonably distributed, so as to achieve the best assembly process and improve the assembly stability. Preferably, 3.2 < CT4 / (T34 + CP3) < 4.8.

[0055] In this embodiment, the spacer element group further includes a second spacer element located between the second lens and the third lens and at least partially abutting against the image side surface of the second lens. The distance EP23 along the optical axis direction of the optical imaging system from the image side surface of the second spacer element to the object side surface of the third spacer element, the Abbe number V2 of the second lens, the Abbe number V3 of the third lens, and the effective focal length f3 of the third lens satisfy: 2 < EP23 * (V2 + V3) / f3 < 4. By restricting EP23 * (V2 + V3) / f3 within a reasonable range, the balance of refractive index and dispersion among the second lens, the third lens, and the distance between the second and third lenses can be ensured. Furthermore, on the premise of meeting the structural stability, the imaging quality is optimal, and the overall imaging quality of the optical imaging system is improved. Preferably, 2.2 < EP23 * (V2 + V3) / f3 < 3.8.

[0056] In this embodiment, the spacer element group further includes a second spacer element located between the second lens and the third lens and at least partially abutting against the image side surface of the second lens. The outer diameter D2s of the object side surface of the second 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: -4 < D2s / R3 * N2 < 1. By restricting D2s / R3 * N2 within a reasonable range, while ensuring the refraction angle of the light passing through the second lens, the size of the second spacer element can be controlled, and the assembly stability can be optimized on the premise of ensuring the imaging performance. Preferably, -3.8 < D2s / R3 * N2 < 0.8.

[0057] In this embodiment, the spacer element group further includes a second spacer element located between the second lens and the third lens and at least partially abutting against the image side surface of the second lens. The effective focal length f2 of the second lens, the outer diameter D2m of the image side surface of the second spacer element, and the inner diameter d2s of the object side surface of the second spacer element satisfy: -2.5 < f2 / (D2m - d2s) < 0. By restricting f2 / (D2m - d2s) within a reasonable range, it can be ensured that the light rays diverged by the second lens can maximize the quality of the imaging light rays when passing through the second spacer element, reduce the generation of stray light rays, and thus improve the imaging quality of the optical imaging system. Preferably, -2.0 < f2 / (D2m - d2s) < -0.2.

[0058] In this embodiment, the spacer element group further includes a first spacer element located between the first lens and the second lens and at least partially abutting against the image side surface of the first lens, and a second spacer element located between the second lens and the third lens and at least partially abutting against the image side surface of the second lens. The combined focal length f12 of the first lens and the second lens, the inner diameter d1s of the object side surface of the first spacer element, and the inner diameter d2s of the object side surface of the second spacer element satisfy: -4 < f12 / (d1s + d2s) < -1. By restricting f12 / (d1s + d2s) within a reasonable range, it can be ensured that the light rays diverged by the first lens and the second lens can maximize the quality of the imaging light rays when passing through the first spacer element and the second spacer element, reduce the generation of stray light rays, and thus improve the imaging quality of the optical imaging system. Preferably, -3.8 < f12 / (d1s + d2s) < -1.2.

[0059] In this embodiment, the inner diameter d0s of the object side end surface of the lens barrel and the entrance pupil diameter EPD of the optical imaging system satisfy: 0.8 < d0s / EPD < 1.8. By restricting d0s / EPD within a reasonable range, the ratio of the light passing hole of the lens barrel to the entrance pupil diameter can be ensured, the light passing amount can be maximally guaranteed, and the imaging quality of the optical imaging system can be improved. Preferably, 1.0 < d0s / EPD < 1.6.

[0060] In this embodiment, the spacer element group further includes a first spacer element located between the first lens and the second lens and at least partially abutting against the image side surface of the first lens, and a second spacer element located between the second lens and the third lens and at least partially abutting against the image side surface of the second lens. The distance EP23 from the image side surface of the second spacer element to the object side surface of the third spacer element along the optical axis direction of the optical imaging system and the distance EP12 from the image side surface of the first spacer element to the object side surface of the second spacer element along the optical axis direction satisfy: 0.8 < EP12 / EP23 < 3. By restricting EP12 / EP23 within a reasonable range, the edge thickness ratio of the second lens and the third lens can be controlled, the edge thickness distribution of the lens group can be controlled, and the assembly stability can be improved. Preferably, 0.85 < EP12 / EP23 < 2.85.

[0061] In this embodiment, the spacer element group further includes a first spacer element located between the first lens and the second lens and at least partially abutting against the image side surface of the first lens. The outer diameter D1m of the image side surface of the first spacer element and the curvature radius R1 of the object side surface of the first lens satisfy: 1 < D1m / R1 < 2.5. By restricting D1m / R1 within a reasonable range, the outer diameter of the first lens can be controlled, thereby ensuring the processing performance and assembly reliability of the first lens. Preferably, 1.2 < D1m / R1 < 2.3.

[0062] In this embodiment, the spacer element group further includes a first spacer element located between the first lens and the second lens and at least partially abutting against the image side surface of the first lens, and a second spacer element located between the second lens and the third lens and at least partially abutting against the image side surface of the second lens. The distance EP12 along the optical axis direction of the optical imaging system from the image side surface of the first spacer element to the object side surface of the second spacer element, and the axial distance SAG11 between the intersection of the object side surface of the first lens and the optical axis and the vertex of the effective radius of the object side surface of the first lens satisfy: 1 < EP12 / SAG11 < 2. By restricting EP12 / SAG11 within a reasonable range, the thickening ratio of the first lens can be controlled, thereby ensuring the processability of the first lens. Preferably, 1 < EP12 / SAG11 < 1.9.

[0063] In this embodiment, the spacer element group further includes a first spacer element located between the first lens and the second lens and at least partially abutting against the image side surface of the first lens, and a first auxiliary spacer element located between the first spacer element and the second lens and at least partially abutting against the image side surface of the first spacer element. The outer diameter D1bm of the image side surface of the first auxiliary spacer element, the inner diameter d1bm of the image side surface of the first auxiliary spacer element, and the effective focal length f2 of the second lens satisfy: -5.5 < (D1bm + d1bm) / f2 < -2. By restricting (D1bm + d1bm) / f2 within a reasonable range, while ensuring the imaging quality, the annulus width of the first auxiliary spacer element can be controlled, improving the processing feasibility of the first auxiliary spacer element and the assembly stability of the optical imaging system. Preferably, -5.2 < (D1bm + d1bm) / f2 < -2.2.

[0064] In this embodiment, the inner diameter d0m of the image side end surface of the lens barrel and the maximum effective radius DT42 of the image side surface of the fourth lens satisfy: 0 < d0m / DT42 < 5. By restricting d0m / DT are within a reasonable range, it can be ensured that the light rays diverging from the fourth lens can pass through the image side end surface of the lens barrel, maximizing the quality of the imaging light rays, reducing the generation of stray light rays, and thereby improving the imaging quality of the optical imaging system. Preferably, 1.0 < d0m / DT42 < 4.8.

[0065] Second Embodiment

[0066] Such as Figures 1 to 24As shown, the optical imaging system includes a lens group, a spacer element group, and a lens barrel. The lens group, from the object side to the image side, includes a first lens to a fourth lens in sequence. The first lens has a positive optical power and a convex object side. The second lens has a negative optical power and a concave image side. The third lens has a positive optical power, a convex object side, and a concave image side. The fourth lens has a positive optical power, a convex object side, and a concave image side. The spacer element group includes at least a second spacer element located between the second and third lenses and at least partially abutting the image side of the second lens. The lens barrel is used to house the lens group and the spacer element group. The effective focal length f2 of the second lens, the outer diameter D2m of the image side of the second spacer element, and the inner diameter d2s of the object side of the second spacer element satisfy the following condition: -2.5 < f2 / (D2m-d2s) < 0.

[0067] This application provides a four-lens optical imaging system. By rationally matching the optical power and surface shape of the four lenses, light is converged before entering the imaging front. However, there is a lot of stray light in the optical imaging system, which seriously affects the image cleanliness. This application can control the direction of light at the second lens by controlling the effective focal length of the second lens and the inner and outer diameters of the second spacer element. The inner diameter of the second spacer element can intercept stray light transmitted from the front and reflected back from the third lens to the maximum extent, ensuring the quality of the imaging light and improving the quality of the optical imaging system.

[0068] Preferably, -2.0 < f2 / (D2m-d2s) < -0.2.

[0069] This embodiment may also include other conditional expressions from the first embodiment, which will not be elaborated here.

[0070] Third Implementation Method

[0071] like Figures 1 to 24As shown, the optical imaging system includes a lens group, a spacer element group, and a lens barrel. The lens group, from the object side to the image side, sequentially includes a first lens to a fourth lens. The first lens has positive optical power and a convex object side. The second lens has negative optical power and a concave image side. The third lens has positive optical power, a convex object side, and a concave image side. The fourth lens has positive optical power, a convex object side, and a concave image side. The spacer element group includes at least a first spacer element located between the first and second lenses and at least partially abutting the image side of the first lens, and a second spacer element located between the second and third lenses and at least partially abutting the image side of the second lens. The lens barrel is used to house the lens group and the spacer element group. The combined focal length f12 of the first and second lenses, the inner diameter d1s of the object side of the first spacer element, and the inner diameter d2s of the object side of the second spacer element satisfy the following condition: -4 <f12 / (d1s+d2s)<-1。

[0072] This application provides a four-lens optical imaging system. By rationally matching the optical power and surface shape of the four lenses, light is converged before entering the imaging front. However, there is a lot of stray light in the optical imaging system, which seriously affects the image cleanliness. This application can control the direction of light at the first and second lenses by controlling the combined focal length of the first and second lenses and the inner diameter of the first and second spacer elements. The inner diameter of the first and second spacer elements can intercept stray light transmitted in front and reflected back by the third lens to the maximum extent, ensuring the quality of the imaging light and improving the quality of the optical imaging system.

[0073] Preferably, -3.8 <f12 / (d1s+d2s)<-1.2。

[0074] This embodiment may also include other conditional expressions from the first embodiment, which will not be elaborated here.

[0075] Optionally, the aforementioned optical imaging system may further include a filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface. The optical imaging system in this application may employ multiple lenses, such as the four lenses described above. By rationally allocating the effective focal length, surface shape, center thickness of each lens, and on-axis distance between each lens, the aperture of the optical imaging system can be effectively increased, the sensitivity of the lens reduced, and the manufacturability of the lens improved. This makes the optical imaging system more conducive to manufacturing and suitable for portable electronic devices such as smartphones.

[0076] Figure 1 A schematic diagram of the structure of an optical imaging system of this application is shown. Figure 1The accompanying drawings also indicate parameters such as d1s, d3m, and D2m to provide a clear and intuitive understanding of their meaning. To facilitate the demonstration of the optical imaging system structure and specific surface features, these parameters will not be shown in the subsequent descriptions of specific embodiments.

[0077] Where Dis refers to the outer diameter of the object-side surface of the i-th spacer element, dis refers to the inner diameter of the object-side surface of the i-th spacer element, Dim refers to the outer diameter of the image-side surface of the i-th spacer element, dim refers to the inner diameter of the image-side surface of the i-th spacer element, CPi refers to the maximum thickness of the i-th spacer element, which is also the maximum distance along the optical axis from the object-side surface of the i-th spacer element to the image-side surface of the i-th spacer element, and EPij refers to the distance along the optical axis between the image-side surface of the i-th spacer element and the object-side surface of the j-th spacer element, where i and j are both positive integers greater than or equal to 1. d0s is the inner diameter of the object-side end face of the lens barrel, and D0m is the outer diameter of the image-side end face of the lens barrel. The maximum height L of the lens barrel P0 refers to the maximum distance along the optical axis from the object-side end face of the lens barrel P0 to the image-side end face of the lens barrel P0.

[0078] The following description, with reference to the accompanying drawings, further illustrates examples of specific surface shapes and parameters applicable to the optical imaging systems described above.

[0079] It should be noted that any one of the following embodiments, from Embodiment 1 to Embodiment 9, is applicable to all implementation methods of this application.

[0080] Example 1

[0081] like Figures 2 to 6 The optical imaging system of Embodiment 1 of this application is described in the figure.

[0082] like Figure 2 As shown, the optical imaging system includes, from the object side to the image side, a first lens E1, a first spacer element P1, a first auxiliary spacer element P1b, a first auxiliary element P1c, a second lens E2, a second spacer element P2, a third lens E3, a third spacer element P3, and a fourth lens E4. The third spacer element has the smallest inner diameter among all the spacers, which helps to intercept stray light incident on the imaging surface and improve image cleanliness. Furthermore, the image-side port diameter of the lens barrel is smaller than the object-side port diameter, allowing the lens and spacer elements to be assembled from the object side of the lens barrel.

[0083] like Figure 2 As shown, the object-side surface of the first lens is S1, the image-side surface of the first lens is S2, the object-side surface of the second lens is S3, the image-side surface of the second lens is S4, the object-side surface of the third lens is S5, the image-side surface of the third lens is S6, the object-side surface of the fourth lens is S7, and the image-side surface of the fourth lens is S8.

[0084] Table 1 shows the basic structural parameters of the optical imaging system in Embodiment 1, where the units for radius of curvature, thickness / distance, and effective focal length are all millimeters (mm).

[0085] Face number Surface type radius of curvature thickness Refractive index Abbe number Conic coefficient OBJ spherical endless endless S1(STO) aspherical 3.7417 1.0000 1.55 56.14 0.0066 S2 aspherical -12.2712 0.7686 1.7868 S3 aspherical -15.9836 0.2825 1.58 32.55 -5.5189 S4 aspherical 1.7401 0.5028 -3.1310 S5 aspherical 3.5264 0.4446 1.58 33.73 -0.5865 S6 aspherical 13.0376 0.0748 50.6063 S7 aspherical 2.9109 0.4337 1.54 56.00 0.9027 S8 aspherical 5.8459 0.5985 0.7900

[0086] Table 1

[0087] In this embodiment, the first to fourth lenses are all aspherical lenses, and the surface shape of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0088]

[0089] Where x is the distance vector from the vertex of the aspherical surface at a height 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 radius of curvature R in Table 1 above; k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 2 below gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28, A30 that can be used for each aspherical mirror in this embodiment.

[0090] Face number A4 A6 A8 A10 A12 A14 A16 S1 3.8205E-02 -2.3181E-03 2.2875E-03 4.9132E-04 -4.6746E-04 -8.4423E-04 -7.8851E-04 S2 3.2524E-01 -3.1684E-02 1.0731E-02 -1.1103E-03 3.9004E-04 -5.8134E-04 -3.0237E-04 S3 1.4756E-01 1.3488E-02 3.8121E-04 3.3912E-04 2.4037E-04 -1.9397E-04 2.6386E-04 S4 -5.5046E-03 1.2318E-02 -6.4388E-03 -7.5443E-04 -3.9865E-05 5.0205E-05 5.4510E-04 S5 3.7252E-03 1.1031E-02 -1.8122E-03 -3.0183E-03 -8.1139E-04 -6.1386E-04 5.4317E-05 S6 7.8082E-02 1.9329E-02 3.8332E-04 -1.9542E-03 -8.8651E-05 -7.6365E-04 1.3676E-04 S7 -2.0722E-01 6.0604E-03 1.0810E-03 8.0606E-04 1.1622E-03 -2.0524E-04 1.0638E-04 S8 -4.6873E-02 -2.6660E-03 1.1086E-03 3.2961E-04 4.1543E-04 5.5143E-05 -1.5252E-05 Face number A18 A20 A22 A24 A26 A28 A30 S1 -5.0449E-04 -2.6250E-04 -9.4331E-05 2.9453E-06 4.8605E-05 3.5098E-05 2.0304E-05 S2 -2.3230E-04 -7.9801E-05 -6.5951E-05 1.9172E-05 2.1160E-05 1.9228E-05 8.6772E-06 S3 -8.2913E-05 6.0359E-05 -2.1677E-04 2.9678E-05 -1.3229E-04 1.1328E-06 -3.1439E-05 S4 2.1673E-04 4.9240E-04 8.3749E-06 1.5323E-04 3.5311E-06 1.8402E-05 3.6306E-06 S5 -2.8216E-04 9.1920E-05 1.3097E-05 1.4727E-05 1.1988E-05 3.6122E-06 -3.6031E-06 S6 -2.3109E-04 4.0483E-05 8.8069E-06 3.2684E-05 -3.4076E-06 1.5905E-05 -9.9810E-06 S7 -3.1526E-05 9.3135E-06 -1.3369E-05 3.0198E-05 -1.4560E-05 1.4386E-05 -9.5345E-06 S8 3.3489E-05 -8.9256E-06 -6.4104E-06 8.0232E-06 -3.6180E-06 3.7137E-06 -1.2330E-06

[0091] Table 2

[0092] Figure 3 The on-axis chromatic aberration curve of the optical imaging system of Embodiment 1 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the optical imaging system. Figure 4 The astigmatism curves of the optical imaging system of Embodiment 1 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 5 The distortion curves of the optical imaging system of Embodiment 1 are shown, which represent the distortion magnitude values ​​corresponding to different field of view angles. Figure 6 The magnification chromatic aberration curve of the optical imaging system of Embodiment 1 is shown, which represents the deviation of light at different image heights on the imaging surface after passing through the optical imaging system.

[0093] according to Figures 3 to 6 As can be seen, the optical imaging system given in Example 1 can achieve good imaging quality.

[0094] Example 2

[0095] The difference from Embodiment 1 is that the parameters of the lens barrel P0 and the spacer element are different.

[0096] like Figure 7 The image shows an optical imaging system according to Embodiment 2 of this application. For the sake of brevity, descriptions similar to those in Embodiment 1 are omitted.

[0097] In Embodiment 2, the curvature radius, center thickness, and other parameters of the first to fourth lenses, as well as the spacing between the lenses, are the same as in Embodiment 1, as shown in Tables 1 and 2. However, at least some parameters, such as the lens barrel P0, the thickness of the spacer element, the inner diameter and outer diameter of the spacer element, and the distance between the spacer elements, are different. Therefore, the imaging quality of the optical imaging system in this embodiment is as follows: Figures 3 to 6 As shown.

[0098] like Figure 7 As shown, there are only two spacer elements between the first lens and the second lens, which reduces the difficulty of assembly while ensuring the stability of the assembly. The object-side port diameter of the lens barrel is smaller than the image-side port diameter, so that the lens and spacer elements are assembled from the image side of the lens barrel.

[0099] Example 3

[0100] The difference from Embodiment 1 is that the parameters of the lens barrel P0 and the spacer element are different.

[0101] like Figure 8 The image shows an optical imaging system according to Embodiment 3 of this application. For the sake of brevity, descriptions similar to those in Embodiment 1 are omitted.

[0102] In Embodiment 3, the curvature radius, center thickness, and other parameters of the first to fourth lenses, as well as the spacing between the lenses, are the same as in Embodiment 1, as shown in Tables 1 and 2. However, at least some parameters, such as the lens barrel P0, the thickness of the spacer element, the inner diameter and outer diameter of the spacer element, and the distance between the spacer elements, are different. Therefore, the imaging quality of the optical imaging system in this embodiment is as follows: Figures 3 to 6 As shown.

[0103] like Figure 8 As shown, there are only two spacer elements between the first lens and the second lens, which reduces the difficulty of assembly while ensuring assembly stability.

[0104] Example 4

[0105] The difference from Embodiment 1 is that the parameters of the lens barrel P0, the spacer element, and the lens are different.

[0106] like Figures 9 to 13 The optical imaging system of Embodiment 4 of this application is described in the figure.

[0107] like Figure 9As shown, the optical imaging system includes, from the object side to the image side, a first lens E1, a first spacer element P1, a first auxiliary spacer element P1b, a second lens E2, a second spacer element P2, a third lens E3, a third spacer element P3, and a fourth lens E4. The third spacer element has the smallest inner diameter among all the spacer elements, which is beneficial for intercepting stray light incident on the imaging surface and improving image cleanliness. Furthermore, the image-side port diameter of the lens barrel is smaller than the object-side port diameter, allowing the lenses and spacers to be assembled from the object side of the lens barrel.

[0108] like Figure 9 As shown, the object-side surface of the first lens is S1, the image-side surface of the first lens is S2, the object-side surface of the second lens is S3, the image-side surface of the second lens is S4, the object-side surface of the third lens is S5, the image-side surface of the third lens is S6, the object-side surface of the fourth lens is S7, and the image-side surface of the fourth lens is S8.

[0109] Table 3 shows the basic structural parameters of the optical imaging system in Embodiment 4, where the units for radius of curvature, thickness / distance, and effective focal length are all millimeters (mm).

[0110] Face number Surface type radius of curvature thickness Refractive index Abbe number Conic coefficient OBJ spherical endless endless S1(STO) aspherical 2.7462 1.1141 1.55 56.14 0.0193 S2 aspherical -180.8562 0.3933 99.0000 S3 aspherical 50.0000 0.3087 1.62 24.45 -99.0000 S4 aspherical 1.7657 0.2126 -3.4465 S5 aspherical 4.6289 0.6187 1.65 23.18 0.8133 S6 aspherical 8.8828 0.1210 36.1561 S7 aspherical 1.7805 0.5072 1.63 25.62 0.1435 S8 aspherical 2.3726 0.6281 -1.3563

[0111] Table 3

[0112] Table 3 also shows the object side surface S15, the image side surface S16, and the imaging surface S17 of the filter.

[0113] In this embodiment, the first to fourth lenses are all aspherical lenses, and the surface shape of each aspherical lens can be defined using, but is not limited to, formula (1) in Embodiment 1. Table 4 below shows the higher-order coefficients that can be used for each aspherical lens in this embodiment.

[0114] Face number A4 A6 A8 A10 A12 A14 A16 S1 2.6716E-02 -3.0561E-03 -1.3863E-03 -7.9351E-04 -1.3518E-04 -7.1486E-05 -1.3196E-05 S2 1.5549E-01 -2.2413E-02 2.7563E-03 -2.2708E-03 6.6851E-04 -3.0124E-04 9.2253E-05 S3 1.2781E-02 8.4685E-03 3.6033E-03 -2.8497E-03 1.3906E-03 -6.1365E-04 1.9720E-04 S4 -4.6191E-02 1.3433E-02 -1.3569E-03 1.3724E-03 -2.6814E-04 8.7289E-05 -7.9792E-05 S5 1.0063E-02 3.3932E-03 -1.1070E-02 4.9974E-03 -1.8446E-03 6.4437E-04 -2.2645E-04 S6 2.9872E-02 2.4720E-02 -1.9446E-02 7.2811E-03 -3.2406E-03 1.2842E-03 -4.9744E-04 S7 -2.6106E-01 2.5428E-02 -1.5087E-02 5.9883E-03 -2.9936E-03 1.3016E-03 -5.4062E-04 S8 -6.9014E-02 1.1188E-02 -1.5109E-03 6.0268E-04 -2.2474E-04 8.8448E-05 -2.6578E-05 Face number A18 A20 A22 A24 A26 A28 A30 S1 -1.2422E-06 -2.9010E-06 5.4958E-07 3.0636E-08 4.4208E-07 0.0000E+00 0.0000E+00 S2 -1.0225E-05 -7.4385E-06 7.8696E-06 -2.3144E-06 2.1865E-07 0.0000E+00 0.0000E+00 S3 -2.0350E-05 -3.5822E-05 3.7525E-05 -2.0166E-05 5.9410E-06 -7.1843E-07 0.0000E+00 S4 1.0226E-04 -9.5898E-05 4.5766E-05 -7.1194E-06 -2.7333E-06 8.7580E-07 0.0000E+00 S5 1.0197E-04 -6.7533E-05 2.2249E-05 3.8538E-06 -5.7234E-06 1.7250E-06 0.0000E+00 S6 1.7381E-04 -7.5021E-05 2.8368E-05 -6.2424E-06 0.0000E+00 0.0000E+00 0.0000E+00 S7 1.9815E-04 -7.5990E-05 2.8757E-05 -7.7970E-06 1.0017E-06 0.0000E+00 0.0000E+00 S8 1.3623E-06 4.0980E-07 -3.5107E-07 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0115] Table 4

[0116] Figure 10 The on-axis chromatic aberration curve of the optical imaging system of Embodiment 4 is shown, which represents the deflection of the focal point after light of different wavelengths passes through the optical imaging system. Figure 11 The astigmatism curves of the optical imaging system of Embodiment 4 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 12 The distortion curves of the optical imaging system of Embodiment 4 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. Figure 13 The magnification chromatic aberration curve of the optical imaging system of Embodiment 4 is shown, which represents the deviation of light at different image heights on the imaging surface after passing through the optical imaging system.

[0117] according to Figures 10 to 13As can be seen, the optical imaging system given in Example 4 can achieve good imaging quality.

[0118] Example 5

[0119] The difference from Embodiment 4 is that the parameters of the lens barrel P0 and the spacer element are different.

[0120] like Figure 14 The image shows an optical imaging system according to Embodiment 5 of this application. For the sake of brevity, descriptions similar to those in Embodiment 4 will be omitted.

[0121] In Embodiment 5 and Embodiment 4, the first to fourth lenses of the optical imaging system have the same parameters such as radius of curvature, center thickness, and spacing between them, as shown in Tables 3 and 4. However, at least some parameters differ, including the lens barrel P0, the thickness of the spacer element, the inner diameter and outer diameter of the spacer element, and the distance between the spacer elements. Therefore, the imaging quality of the optical imaging system in this embodiment is as follows: Figures 10 to 13 As shown.

[0122] like Figure 14 As shown, there is only one spacer between the first lens and the second lens, which reduces the assembly difficulty while ensuring assembly stability. The object-side port diameter of the lens barrel is smaller than the image-side port diameter, allowing the lens and spacer to be assembled from the image side of the lens barrel.

[0123] Example 6

[0124] The difference from Embodiment 4 is that the parameters of the lens barrel P0 and the spacer element are different.

[0125] like Figure 15 The image shows an optical imaging system according to Embodiment Six of this application. For the sake of brevity, descriptions similar to those in Embodiment Four will be omitted.

[0126] In Embodiment Six and Embodiment Four, the first to fourth lenses of the optical imaging system have the same parameters such as radius of curvature, center thickness, and spacing between them, as shown in Tables 3 and 4. However, at least some parameters differ, including the lens barrel P0, the thickness of the spacer element, the inner diameter and outer diameter of the spacer element, and the distance between the spacer elements. Therefore, the imaging quality of the optical imaging system in this embodiment is as follows: Figures 10 to 13 As shown.

[0127] like Figure 15 As shown, there is only one spacer between the first lens and the second lens, which reduces the difficulty of assembly while ensuring the stability of the assembly.

[0128] Example 7

[0129] The difference from Embodiment 1 is that the parameters of the lens barrel P0, the spacer element, and the lens are different.

[0130] like Figures 16 to 20 The image shows an optical imaging system according to Embodiment Seven of this application.

[0131] like Figure 16 As shown, the optical imaging system includes, from the object side to the image side, a first lens E1, a first spacer element P1, a first auxiliary spacer element P1b, a second lens E2, a second spacer element P2, a third lens E3, a third spacer element P3, and a fourth lens E4. The third spacer element has the smallest inner diameter among all the spacer elements, which is beneficial for intercepting stray light incident on the imaging surface and improving image cleanliness. Furthermore, the image-side port diameter of the lens barrel is smaller than the object-side port diameter, allowing the lenses and spacers to be assembled from the object side of the lens barrel.

[0132] like Figure 16 As shown, the object-side surface of the first lens is S1, the image-side surface of the first lens is S2, the object-side surface of the second lens is S3, the image-side surface of the second lens is S4, the object-side surface of the third lens is S5, the image-side surface of the third lens is S6, the object-side surface of the fourth lens is S7, and the image-side surface of the fourth lens is S8.

[0133] Table 5 shows the basic structural parameters of the optical imaging system of Embodiment 7, where the units for radius of curvature, thickness / distance, and effective focal length are all millimeters (mm).

[0134]

[0135]

[0136] Table 5

[0137] In this embodiment, the first to fourth lenses are all aspherical lenses, and the surface shape of each aspherical lens can be defined using, but is not limited to, formula (1) in Embodiment 1. Table 6 below gives the higher-order coefficients that can be used for each aspherical lens in this embodiment.

[0138] Face number A4 A6 A8 A10 A12 A14 A16 S1 4.8633E-02 -5.3699E-03 -3.4373E-03 -2.3189E-03 -6.7181E-04 -3.7116E-04 -1.0562E-04 S2 5.5328E-03 -5.6877E-02 1.9961E-02 -7.4721E-03 6.0614E-04 -1.1937E-03 -1.5458E-03 S3 -1.6240E-01 1.5973E-02 1.3445E-02 5.7738E-03 2.7849E-03 -2.3590E-04 -1.5907E-03 S4 -5.4152E-03 4.4529E-02 -3.1649E-03 1.2631E-03 9.8778E-04 -6.4169E-04 4.4762E-04 S5 8.4657E-03 5.6351E-03 -2.4873E-03 1.5849E-03 -1.9149E-04 9.5444E-05 4.0134E-05 S6 8.8394E-02 -3.2008E-03 -1.3059E-03 9.2843E-04 1.4334E-04 -9.6955E-05 7.7171E-05 S7 -2.5631E-01 -3.4210E-03 1.9843E-03 -8.7066E-04 9.9956E-04 -3.9945E-04 1.3588E-04 S8 -1.1019E-02 -9.0525E-03 2.6694E-03 -7.9450E-04 5.4004E-04 -1.8349E-04 5.5664E-05 Face number A18 A20 A22 A24 A26 A28 A30 S1 -2.6994E-05 -2.9714E-06 3.2109E-06 -5.1258E-06 -5.4594E-08 5.3109E-07 1.2292E-06 S2 -4.0136E-04 -1.1461E-04 -1.0700E-04 -1.2133E-04 3.5697E-05 2.8302E-05 -3.9626E-06 S3 -1.2599E-03 -6.4589E-04 -3.0840E-04 -2.4145E-04 -6.9095E-05 0.0000E+00 0.0000E+00 S4 -7.0765E-05 4.5206E-05 -3.9509E-05 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S5 1.3444E-04 -3.7843E-05 -2.4444E-05 -6.0050E-06 0.0000E+00 0.0000E+00 0.0000E+00 S6 7.0727E-05 -3.6582E-05 -1.0929E-05 -2.1122E-06 0.0000E+00 0.0000E+00 0.0000E+00 S7 1.9233E-05 -2.5379E-05 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S8 5.8033E-06 -6.3862E-06 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0139] Table 6

[0140] Figure 17 The on-axis chromatic aberration curve of the optical imaging system of Embodiment 7 is shown, which represents the deflection of the focal point after light of different wavelengths passes through the optical imaging system. Figure 18 The astigmatism curves of the optical imaging system of Embodiment 7 are shown, representing the meridional image plane curvature and the sagittal image plane curvature. Figure 19 The distortion curves of the optical imaging system of Embodiment 7 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. Figure 20 The magnification chromatic aberration curve of the optical imaging system of Embodiment 7 is shown, which represents the deviation of light at different image heights on the imaging surface after passing through the optical imaging system.

[0141] according to Figures 17 to 20 As can be seen, the optical imaging system given in Example 7 can achieve good imaging quality.

[0142] Example 8

[0143] The difference from Embodiment 7 is that the parameters of the lens barrel P0 and the spacer element are different.

[0144] like Figure 21 The image shows an optical imaging system according to Embodiment 8 of this application. For the sake of brevity, descriptions similar to those in Embodiment 7 will be omitted.

[0145] In Embodiment 8 and Embodiment 7, the first to fourth lenses of the optical imaging system have the same parameters such as radius of curvature, center thickness, and spacing between them, as shown in Tables 5 and 6. However, at least some parameters differ, including the lens barrel P0, the thickness of the spacer element, the inner diameter and outer diameter of the spacer element, and the distance between the spacer elements. Therefore, the imaging quality of the optical imaging system in this embodiment is as follows: Figures 17 to 20 As shown.

[0146] like Figure 21 As shown, there is only one spacer between the first lens and the second lens, which reduces the difficulty of assembly while ensuring the stability of the assembly.

[0147] Example 9

[0148] The difference from Embodiment 7 is that the parameters of the lens barrel P0 and the spacer element are different.

[0149] like Figure 22 The image shows an optical imaging system according to Embodiment Nine of this application. For the sake of brevity, descriptions similar to those in Embodiment Seven are omitted.

[0150] In Embodiment 9 and Embodiment 7, the first to fourth lenses of the optical imaging system have the same parameters such as radius of curvature, center thickness, and spacing between them, as shown in Tables 5 and 6. However, at least some parameters such as the lens barrel P0, the thickness of the spacer element, the inner diameter and outer diameter of the spacer element, and the distance between the spacer elements are different. Therefore, the imaging quality of the optical imaging system in this embodiment is as follows: Figures 17 to 20 As shown.

[0151] like Figure 22 As shown, the object-side port diameter of the lens barrel is smaller than the image-side port diameter, so that the lens and spacer element are assembled from the image side of the lens barrel.

[0152] In summary, Examples 1 to 9 satisfy the relationships shown in Table 7.

[0153] Conditional / Example 1 2 3 4 5 6 7 8 9 f4 / f 0.7522 0.7522 0.7522 1.1055 1.1055 1.1055 0.8350 0.8350 0.8350 D3m / R7 2.3657 2.8105 2.3657 2.5669 2.9606 2.5669 2.8025 2.0853 2.8492 f3 / f 1.2459 1.2459 1.2459 0.5531 0.5531 0.5531 0.8345 0.8345 0.8345 CT4 / (T34+CP3) 3.6485 3.5465 3.6485 3.6932 3.5326 3.6932 4.4352 4.3454 4.4352 R5 / d3s*N3 2.8317 2.8015 2.8317 1.9928 1.9928 1.9928 2.4140 2.4176 2.4001 EP23*(V2+V3) / f3 2.6345 2.7402 2.6345 3.1547 3.1407 3.1547 3.2629 3.3833 2.9524 D2s / R3*N2 0.1389 0.1587 0.1389 -0.0839 -0.0932 -0.0839 -3.3004 -3.5411 -3.2549 f2 / (D2m-d2s) -1.8913 -1.8462 -1.8913 -1.5621 -1.1929 -1.5621 -0.7757 -0.6678 -0.8008 d0s / EPD 1.3136 1.1200 1.3136 1.2959 1.1168 1.2959 1.4244 1.5273 1.2134 f12 / (d1s+d2s) -3.3747 -3.0794 -3.2850 -1.6669 -1.6664 -1.6817 -1.9617 -2.1549 -1.9870 EP12 / EP23 1.2070 1.2015 0.9094 2.2810 2.2756 2.1350 2.2524 2.3876 2.4056 EP12 / SAG11 1.3458 1.3934 1.0140 1.1615 1.1536 1.0872 1.6251 1.7862 1.5704 D1m / R1 1.5920 1.7129 1.5257 1.7613 1.8866 1.7613 1.8168 2.0117 1.7763 (D1bm+d1bm) / f2 -2.7848 -2.9119 -2.5417 -3.4672 / / -4.7121 / -4.5864 d0m / DT42 2.3945 3.9263 2.3945 2.5236 4.0316 4.3003 3.0749 2.4791 4.0281

[0154] Table 7

[0155] Table 8 provides some parameters of the optical imaging systems of Examples 1 to 9.

[0156]

[0157]

[0158] Table 8

[0159] Table 9 provides some optical parameters of the first to fourth lenses of the optical imaging systems of Embodiments 1 to 9.

[0160] Basic Data / Example 1 2 3 4 5 6 7 8 9 EPD (mm) 3.5948 3.5948 3.5948 3.8808 3.8808 3.8808 3.8866 3.8866 3.8866 f(mm) 11.2170 11.2170 11.2170 11.9938 11.9938 11.9938 11.9399 11.9399 11.9399 f1(mm) 4.9631 4.9631 4.9631 5.0261 5.0261 5.0261 2.9788 2.9788 2.9788 f2 (mm) -2.9410 -2.9410 -2.9410 -2.5946 -2.5946 -2.5946 -1.8546 -1.8546 -1.8546 f3 (mm) 13.9752 13.9752 13.9752 6.6339 6.6339 6.6339 9.9638 9.9638 9.9638 f4 (mm) 8.4376 8.4376 8.4376 13.2593 13.2593 13.2593 9.9704 9.9704 9.9704 f12 (mm) -20.2750 -20.2750 -20.2750 -10.9749 -10.9749 -10.9749 -13.7420 -13.7420 -13.7420 DT42 (mm) 1.3076 1.3076 1.3076 1.3322 1.3322 1.3322 1.3396 1.3396 1.3396 SAG11 (mm) 0.6933 0.6933 0.6933 0.8876 0.8876 0.8876 0.7138 0.7138 0.7138

[0161] Table 9

[0162] This application also provides an imaging device, whose electronic photosensitive element can be a photocoupled device (CCD) or a complementary metal oxide semiconductor device (CMOS). The imaging device can be a stand-alone imaging device such as a digital camera, or an imaging module integrated into a mobile electronic device such as a mobile phone. The imaging device is equipped with the optical imaging system described above.

[0163] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0164] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0165] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0166] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection 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 optical imaging system includes: The lens group, from the object side to the image side of the optical imaging system, sequentially includes a first lens to a fourth lens. The first lens has a positive optical power and its object side is convex. The second lens has a negative optical power and its image side is concave. The third lens has a positive optical power, its object side is convex, and its image side is concave. The fourth lens has a positive optical power, its object side is convex, and its image side is concave. A group of spacers, the group of spacers including at least a third spacer located between the third lens and the fourth lens and at least partially abutting the image side of the third lens; A lens barrel for housing the lens group and the spacer element group; Wherein, the effective focal length f3 of the third lens and the effective focal length f of the optical imaging system satisfy the following condition: 0.5531≤f3 / f≤1.2459; The radius of curvature R5 of the object side surface of the third lens, the inner diameter d3s of the object side surface of the third spacer element, and the refractive index N3 of the third lens satisfy the following condition: 1.9928≤R5 / d3s*N3≤2.8317. The central thickness CT4 of the fourth lens on the optical axis of the optical imaging system, the air gap T34 between the third and fourth lenses on the optical axis, and the maximum thickness CP3 of the third spacer element along the optical axis direction satisfy the following: 3.5326≤CT4 / (T34+CP3)≤4.4352.

2. The optical imaging system according to claim 1, characterized in that, The effective focal length f4 of the fourth lens and the effective focal length f of the optical imaging system satisfy the following condition: 0.7522≤f4 / f≤1.1055. The outer diameter D3m of the image side of the third spacer element and the radius of curvature R7 of the object side of the fourth lens satisfy the following condition: 2.0853≤D3m / R7≤2.9606.

3. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a second spacer element located between the second lens and the third lens and at least partially abutting the image side of the second lens. The distance EP23 from the image side of the second spacer element to the object side of the third spacer element along the optical axis of the optical imaging system, the Abbe number V2 of the second lens, the Abbe number V3 of the third lens, and the effective focal length f3 of the third lens satisfy the following: 2.6345≤EP23*(V2+V3) / f3≤3.3833.

4. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a second spacer element located between the second lens and the third lens and at least partially abutting the image side of the second lens. The outer diameter D2s of the object side of the second spacer element, the radius of curvature R3 of the object side of the second lens, and the refractive index N2 of the second lens satisfy the following: -3.5411≤D2s / R3*N2≤0.1587.

5. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a second spacer element located between the second lens and the third lens and at least partially abutting the image side of the second lens. The effective focal length f2 of the second lens, the outer diameter D2m of the image side of the second spacer element, and the inner diameter d2s of the object side of the second spacer element satisfy the following: -1.8913≤f2 / (D2m-d2s)≤-0.6678.

6. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a first spacer element located between the first lens and the second lens and at least partially abutting the image side of the first lens, and a second spacer element located between the second lens and the third lens and at least partially abutting the image side of the second lens. The combined focal length f12 of the first lens and the second lens, the inner diameter d1s of the object side of the first spacer element, and the inner diameter d2s of the object side of the second spacer element satisfy the following: -3.3747≤f12 / (d1s+d2s)≤-1.6664.

7. The optical imaging system according to claim 1, characterized in that, The inner diameter d0s of the object-side end face of the lens barrel and the entrance pupil diameter EPD of the optical imaging system satisfy the following condition: 1.1168≤d0s / EPD<1.

6.

8. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a first spacer element located between the first lens and the second lens and at least partially abutting the image side of the first lens, and a second spacer element located between the second lens and the third lens and at least partially abutting the image side of the second lens. The distance EP23 between the image side of the second spacer element and the object side of the third spacer element along the optical axis of the optical imaging system, and the distance EP12 between the image side of the first spacer element and the object side of the second spacer element along the optical axis satisfy the following: 0.9094≤EP12 / EP23≤2.4056.

9. The optical imaging system according to any one of claims 1 to 8, characterized in that, The spacer element group further includes a first spacer element located between the first lens and the second lens and at least partially abutting the image side of the first lens. The outer diameter D1m of the image side of the first spacer element and the radius of curvature R1 of the object side of the first lens satisfy the following: 1.5257≤D1m / R1≤2.0117.

10. The optical imaging system according to any one of claims 1 to 8, characterized in that, The spacer element group further includes a first spacer element located between the first lens and the second lens and at least partially abutting the image-side surface of the first lens, and a second spacer element located between the second lens and the third lens and at least partially abutting the image-side surface of the second lens. The distance EP12 between the image-side surface of the first spacer element and the object-side surface of the second spacer element along the optical axis of the optical imaging system, and the axial distance SAG11 between the intersection of the object-side surface of the first lens and the optical axis and the vertex of the effective radius of the object-side surface of the first lens, satisfy the following: 1 <EP12 / SAG11≤1.7862。 11. The optical imaging system according to any one of claims 1 to 8, characterized in that, The spacer element group further includes a first spacer element located between the first lens and the second lens and at least partially abutting the image side of the first lens, and a first auxiliary spacer element located between the first spacer element and the second lens and at least partially abutting the image side of the first spacer element. The outer diameter D1bm of the image side of the first auxiliary spacer element, the inner diameter d1bm of the image side of the first auxiliary spacer element, and the effective focal length f2 of the second lens satisfy the following: -4.7121≤(D1bm+d1bm) / f2≤-2.5417.

12. The optical imaging system according to any one of claims 1 to 8, characterized in that, The inner diameter d0m of the image-side end face of the lens barrel and the maximum effective radius DT42 of the image-side surface of the fourth lens satisfy the following condition: 2.3945≤d0m / DT42≤4.3003.

Images