Optical imaging system

Abstract

The application discloses an optical imaging system, which comprises a lens barrel, an eight-piece lens group and a spacer element group arranged in the lens barrel. The eight-piece lens group comprises, in order from the object side to the image side along the optical axis, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens with positive refractive power and an eighth lens with negative refractive power. The spacer element group comprises a seventh spacer element arranged on the image side of the seventh lens and in contact with the image side of the seventh lens. The radius of curvature R15 of the object side surface of the eighth lens, the radius of curvature R16 of the image side surface of the eighth lens, the inner diameter d7m of the image side surface of the seventh spacer element and the outer diameter D7m of the image side surface of the seventh spacer element satisfy the condition: 4 < D7m / R16 + d7m / R15 < 18. The effective focal length f7 of the seventh lens, the effective focal length f8 of the eighth lens, the central thickness CT8 of the eighth lens on the optical axis and the maximum thickness CP7 of the seventh spacer element satisfy the condition: -45 < f8 / (CT8-CP7)-f7(CT8+CP7) < -6.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical devices, in particular to an eight-piece optical imaging system. BACKGROUND

[0002] With the rapid development of portable electronic products such as smart phones, the imaging requirements of optical imaging systems in portable electronic products such as smart phones are becoming more and more stringent. For example, through optical design of the optical imaging system, the optical imaging system meets the requirement of large image surface.

[0003] In order to meet the requirement of large image surface, the optical imaging system is usually provided in the form of an eight-piece lens structure. In the eight-piece optical imaging system, the last two lenses have a large step difference, which will cause the assembly yield of the optical imaging system to be poor and affect the product competitiveness of the optical imaging system. SUMMARY

[0004] The present application provides an optical imaging system that can at least solve or partially solve at least one problem or other problems existing in the prior art.

[0005] An aspect of the present application provides an optical imaging system, which includes a lens barrel, an eight-piece lens group and a spacer element group disposed in the lens barrel. The eight-piece lens group includes, in order from the object side to the image side along the optical axis, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens having positive refractive power, and an eighth lens having negative refractive power. The object side surface of the eighth lens is convex at the near axis, and the image side surface of the eighth lens is concave at the near axis. The spacer element group includes a seventh spacer element disposed on and in contact with the image side surface of the seventh lens. The radius of curvature R15 of the object side surface of the eighth lens, the radius of curvature R16 of the image side surface of the eighth lens, the inner diameter d7m of the image side surface of the seventh spacer element, and the outer diameter D7m of the image side surface of the seventh spacer element satisfy: 4 < D7m / R16 + d7m / R15 < 18. The effective focal length f7 of the seventh lens, the effective focal length f8 of the eighth lens, the central thickness CT8 of the eighth lens on the optical axis, and the maximum thickness CP7 of the seventh spacer element satisfy: -45 < f8 / (CT8-CP7) - f7(CT8+CP7) < -6.

[0006] According to an exemplary embodiment of the present application, the spacer element group further includes a first spacer element disposed on and in contact with the image side surface of the first lens. The inner diameter d0s of the object side end surface of the lens barrel, the outer diameter D1s of the object side surface of the first spacer element, and the F-number FNO of the optical imaging system satisfy: 7 < d0s x D1s / FNO < 26.

[0007] According to an example embodiment of the present application, the total effective focal length f of the optical imaging system, half of the maximum field angle of the optical imaging system Semi-FOV, and the length L of the lens barrel in the direction of the optical axis satisfy: 55mm 2 < f / tan ( Semi-FOV ) × L < 95mm 2 .

[0008] According to an example embodiment of the present application, the spacer element group further comprises a first spacer element disposed on and in contact with the image side surface of the first lens, wherein the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the inner diameter d1s of the object side surface of the first spacer element, and the outer diameter D1m of the image side surface of the first spacer element satisfy: -25 < ( f2 - f1 ) / ( D1m - d1s ) < -4.

[0009] According to an example embodiment of the present application, the optical imaging system further satisfies: R2 / R1 > 1, R4 / R3 > 0, and R6 / R5 > 0, wherein R1 is the radius of curvature of the object side surface of the first lens, R2 is the radius of curvature of the image side surface of the first lens, R3 is the radius of curvature of the object side surface of the second lens, R4 is the radius of curvature of the image side surface of the second lens, R5 is the radius of curvature of the object side surface of the third lens, and R6 is the radius of curvature of the image side surface of the third lens.

[0010] According to an example embodiment of the present application, the spacer element group further comprises a first spacer element, a second spacer element, and a third spacer element, the first spacer element is disposed on and in contact with the image side surface of the first lens, the second spacer element is disposed on and in contact with the image side surface of the second lens, and the third spacer element is disposed on and in contact with the image side surface of the third lens,

[0011] wherein the radius of curvature R2 of the image side surface of the first lens, the radius of curvature R3 of the object side surface of the second lens, the radius of curvature R4 of the image side surface of the second lens, the radius of curvature R5 of the object side surface of the third lens, the interval EP12 of the first spacer element and the second spacer element along the optical axis, and the interval EP23 of the second spacer element and the third spacer element along the optical axis satisfy: 30 < ( R2 - R3 ) / EP12 + ( R5 - R4 ) / EP23 < 60.

[0012] According to an example embodiment of the present application, the spacer element group further comprises a fourth spacer element disposed on and in contact with the image side surface of the fourth lens, wherein the effective focal length f4 of the fourth lens, the effective focal length f5 of the fifth lens, the inner diameter d4s of the object side surface of the fourth spacer element, and the outer diameter D4s of the object side surface of the fourth spacer element satisfy: -28 < f4 / d4s + f5 / D4s < -1.

[0013] According to an exemplary embodiment of the present application, the spacer element group further includes a sixth spacer element disposed on the image side of the sixth lens and in contact with the image side of the sixth lens. Wherein, the radius of curvature R12 of the image side of the sixth lens, the radius of curvature R13 of the object side of the seventh lens, the inner diameter d6m of the image side of the sixth spacer element, and the outer diameter D6m of the image side of the sixth spacer element satisfy: 6mm < (R13 - R12) / d6m × D6m < 30mm.

[0014] According to an exemplary embodiment of the present application, the spacer element group further includes a fifth spacer element disposed on the image side of the fifth lens and in contact with the image side of the fifth lens. Wherein, the effective focal length f5 of the fifth lens, the effective focal length f6 of the sixth lens, the inner diameter d5m of the image side of the fifth spacer element, and the outer diameter D5m of the image side of the fifth spacer element satisfy: 26 < (f5 × f6) / (D5m × d5m) < 66.

[0015] According to an exemplary embodiment of the present application, the spacer element group further includes a third spacer element and a fourth spacer element. The third spacer element is disposed on the image side of the third lens and in contact with the image side of the third lens. The fourth spacer element is disposed on the image side of the fourth lens and in contact with the image side of the fourth lens. Wherein, the central thickness CT3 of the third lens on the optical axis, the outer diameter D3m of the image side of the third spacer element, the outer diameter D4m of the image side of the fourth spacer element, and the maximum thickness CP4 of the fourth spacer element satisfy: -17 < D4m / CP4 - D3m / CT3 < 0.

[0016] According to an exemplary embodiment of the present application, the spacer element group further includes a first spacer element and a fourth spacer element. The first spacer element is disposed on the image side of the first lens and in contact with the image side of the first lens. The fourth spacer element is disposed on the image side of the fourth lens and in contact with the image side of the fourth lens.

[0017] Wherein, the optical imaging system further satisfies: 0 < fi / dis < 7, i = 1, 4 or 7. When i takes 1, fi represents the effective focal length of the first lens, and dis represents the inner diameter of the object side of the first spacer element; when i takes 4, fi represents the effective focal length of the fourth lens, and dis represents the inner diameter of the object side of the fourth spacer element; when i takes 7, fi represents the effective focal length of the seventh lens, and dis represents the inner diameter of the object side of the seventh spacer element.

[0018] According to an exemplary embodiment of the present application, the spacer element group further includes a fourth spacer element and a fifth spacer element. The fourth spacer element is disposed on the image side surface of the fourth lens and contacts the image side surface of the fourth lens. The fifth spacer element is disposed on the image side surface of the fifth lens and contacts the image side surface of the fifth lens. Wherein, the interval EP45 between the fourth spacer element and the fifth spacer element along the optical axis, the air interval T56 between the fifth lens and the sixth lens on the optical axis, the radius of curvature R8 of the image side surface of the fourth lens and the radius of curvature R11 of the object side surface of the sixth lens satisfy: 0 < (T56 / EP45) × (R8 / R11) < 9.

[0019] According to an exemplary embodiment of the present application, the spacer element group further includes a first spacer element and a second spacer element. The first spacer element is disposed on the image side surface of the first lens and contacts the image side surface of the first lens. The second spacer element is disposed on the image side surface of the second lens and contacts the image side surface of the second lens.

[0020] Wherein, the refractive indices of the second lens and the fifth lens are greater than 1.60, and the optical imaging system further satisfies: EP12 > T12, EP45 < T45, where EP12 is the interval between the first spacer element and the second spacer element along the optical axis, T12 is the air interval between the first lens and the second lens on the optical axis, EP45 is the interval between the fourth spacer element and the fifth spacer element along the optical axis, and T45 is the air interval between the fourth lens and the fifth lens on the optical axis.

[0021] According to an exemplary embodiment of the present application, the spacer element group further includes a sixth spacer element disposed on the image side surface of the sixth lens and contacting the image side surface of the sixth lens. Wherein, the effective focal length f6 of the sixth lens, the effective focal length f7 of the seventh lens, the effective focal length f8 of the eighth lens, the maximum thickness CP6 of the sixth spacer element, the maximum thickness CP7 of the seventh spacer element, and the interval EP67 between the sixth spacer element and the seventh spacer element along the optical axis satisfy: -30 < (f6 + f7 + f8) / (CP6 + EP67 + CP7) < -6.

[0022] According to an exemplary embodiment of the present application, the outer diameter D0s of the object side end face of the lens barrel, the outer diameter D0m of the image side end face of the lens barrel, the total effective focal length f of the optical imaging system, and the effective focal length f8 of the eighth lens satisfy: -17 < (D0m - D0s) / f × f8 < -4.

[0023] This application, by limiting the curvature radius of the relevant surfaces of the seventh and eighth lenses within a certain range, also constrains the inner and outer diameters of the image side of the seventh spacer element. This ensures that the imaging element group formed by the seventh lens, the eighth lens, and the seventh spacer element has an optimal outer diameter step difference, thereby improving the assembly yield and product competitiveness of the optical imaging system. This application also constrains the dimensional relationship between the effective focal length and the relevant center thickness of the seventh and eighth lenses, ensuring that the shapes of the seventh and eighth lenses are uniform and stable, thereby improving the molding and assembly feasibility of the optical imaging system and ensuring the quality of the optical imaging system. Attached Figure Description

[0024] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0025] Figure 1 A schematic diagram of the structure of the optical imaging system according to this application is shown;

[0026] Figure 2 A schematic diagram of the structure of an optical imaging system according to Embodiment 1 of the first embodiment of this application is shown;

[0027] Figure 3 A schematic diagram of the structure of an optical imaging system according to Embodiment 2 of the first embodiment of this application is shown;

[0028] Figure 4 A schematic diagram of the structure of an optical imaging system according to Embodiment 3 of the first embodiment of this application is shown;

[0029] Figures 5A to 5D The on-axis chromatic aberration curve, astigmatism curve, distortion curve, and magnification chromatic aberration curve of the optical imaging system according to the first embodiment of this application are shown respectively.

[0030] Figure 6 A schematic diagram of the structure of an optical imaging system according to Embodiment 1 of the second embodiment of this application is shown;

[0031] Figure 7 A schematic diagram of the structure of an optical imaging system according to Embodiment 2 of the second embodiment of this application is shown;

[0032] Figure 8 A schematic diagram of the structure of an optical imaging system according to Embodiment 3 of the second embodiment of this application is shown;

[0033] Figures 9A to 9D The on-axis chromatic aberration curve, astigmatism curve, distortion curve, and magnification chromatic aberration curve of the optical imaging system according to the second embodiment of this application are shown respectively.

[0034] Figure 10 A schematic diagram of the structure of an optical imaging system according to Embodiment 1 of the third embodiment of this application is shown;

[0035] Figure 11 A schematic diagram of the structure of an optical imaging system according to Embodiment 2 of the third embodiment of this application is shown;

[0036] Figure 12 A schematic diagram of the structure of an optical imaging system according to Embodiment 3 of the third embodiment of this application is shown; and

[0037] Figures 13A to 13D The on-axis chromatic aberration curve, astigmatism curve, distortion curve, and magnification chromatic aberration curve of the optical imaging system according to the third embodiment of this application are shown respectively. Detailed Implementation

[0038] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising" as used in this specification indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0043] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized sense, unless expressly so specified herein.

[0044] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0045] Figure 1 This document illustrates a structural layout diagram and schematic diagrams of some parameters of an optical imaging system according to an exemplary embodiment of this application. Those skilled in the art will understand that some parameters frequently used in the field, such as the outer diameter D1m of the image-side surface of the first spacer element, are not shown in the diagram. Figure 1 As shown in the image. Figure 1 The following are exemplary parameters of the lens barrel and spacer elements of the optical imaging system of this application, to facilitate a better understanding of this application. Figure 1As shown, d1s represents the inner diameter of the object-side surface of the first spacer element, D1s represents the outer diameter of the object-side surface of the first spacer element, D3m represents the outer diameter of the image-side surface of the third spacer element, d4s represents the inner diameter of the object-side surface of the fourth spacer element, D4s represents the outer diameter of the object-side surface of the fourth spacer element, D4m represents the outer diameter of the image-side surface of the fourth spacer element, d5m represents the inner diameter of the image-side surface of the fifth spacer element, D5m represents the outer diameter of the image-side surface of the fifth spacer element, d6m represents the inner diameter of the image-side surface of the sixth spacer element, D6m represents the outer diameter of the image-side surface of the sixth spacer element, d7s represents the inner diameter of the object-side surface of the seventh spacer element, d7m represents the inner diameter of the image-side surface of the seventh spacer element, and D7m represents the outer diameter of the image-side surface of the seventh spacer element. d0s represents the outer diameter of the image-side face of the seventh spacer element, d0s represents the inner diameter of the object-side end face of the lens barrel, D0s represents the outer diameter of the object-side end face of the lens barrel, D0m represents the outer diameter of the image-side end face of the lens barrel, EP12 represents the spacing between the first and second spacer elements along the optical axis, EP23 represents the spacing between the second and third spacer elements along the optical axis, CP4 represents the maximum thickness of the fourth spacer element, EP45 represents the spacing between the fourth and fifth spacer elements along the optical axis, CP6 represents the maximum thickness of the sixth spacer element, EP67 represents the spacing between the sixth and seventh spacer elements along the optical axis, CP7 represents the maximum thickness of the seventh spacer element, and L represents the length of the lens barrel in the direction of the optical axis.

[0046] The features, principles and other aspects of this application are described in detail below.

[0047] like Figures 2 to 4 , Figures 6 to 8 as well as Figures 10 to 12 As shown, an optical imaging system according to an exemplary embodiment of this application may include a lens barrel and an eight-lens group disposed within the lens barrel. The eight-lens group may include a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially along the optical axis from the object side to the image side. An air gap may exist between any two adjacent lenses in the first to eighth lenses. The seventh lens has positive optical power, the eighth lens has negative optical power, and the object side of the eighth lens is convex at the paraxial position, while the image side is concave at the paraxial position.

[0048] The optical imaging system may further include a set of spacer elements disposed within the lens barrel. The set of spacer elements may include a seventh spacer element, which is disposed on the image side of the seventh lens and at least partially contacts the image side of the seventh lens. In one example, the radius of curvature R15 of the object side of the eighth lens, the radius of curvature R16 of the image side of the eighth lens, the inner diameter d7m and the outer diameter D7m of the image side of the seventh spacer element may satisfy: 4 < D7m / R16 + d7m / R15 < 18, and the effective focal length f7 of the seventh lens, the effective focal length f8 of the eighth lens, the central thickness CT8 of the eighth lens on the optical axis, and the maximum thickness CP7 of the seventh spacer element may satisfy: -45 < f8 / (CT8 - CP7) - f7 / (CT8 + CP7) < -6. By controlling the above conditional expressions, in this application, while restricting the radii of curvature of the relevant surfaces of the seventh lens and the eighth lens within a certain range, the inner and outer diameters of the image side of the seventh spacer element are constrained, ensuring that the imaging element group formed by the seventh lens, the eighth lens, and the seventh spacer element has an optimal outer diameter step difference, thereby improving the assembly yield and product competitiveness of the optical imaging system; this application also restricts the dimensional relationships of the effective focal lengths and relevant central thicknesses of the seventh lens and the eighth lens to ensure that the shapes of the seventh lens and the eighth lens are uniform and stable, thereby improving the molding and assembly feasibility of the optical imaging system and ensuring the quality of the optical imaging system.

[0049] In other examples, the set of spacer elements may further include a first spacer element, a second spacer element, a third spacer element, a fourth spacer element, a fifth spacer element, and a sixth spacer element. Among them, the first spacer element is disposed on the image side of the first lens and at least partially contacts the image side of the first lens; the second spacer element is disposed on the image side of the second lens and at least partially contacts the image side of the second lens; the third spacer element is disposed on the image side of the third lens and at least partially contacts the image side of the third lens; the fourth spacer element is disposed on the image side of the fourth lens and at least partially contacts the image side of the fourth lens; the fifth spacer element is disposed on the image side of the fifth lens and at least partially contacts the image side of the fifth lens; the sixth spacer element is disposed on the image side of the sixth lens and at least partially contacts the image side of the sixth lens. Reasonable use of spacer elements can effectively avoid the risk of stray light, reduce interference with image quality, and thereby improve the imaging quality of the optical imaging system.

[0050] In an exemplary embodiment, the lens barrel has an object-side end face close to the first lens and an image-side end face close to the eighth lens. Among them, the inner diameter d0s of the object-side end face of the lens barrel, the outer diameter D1s of the object-side face of the first spacer element, and the f-number FNO of the optical imaging system can satisfy: 7 < d0s × D1s / FNO < 26. By controlling the relationship between the ratio of the inner diameter of the object-side end face of the lens barrel and the outer diameter of the object-side face of the first spacer element and the f-number of the optical imaging system, it is possible to limit the difference in the outer diameters of the imaging elements on the object-side end face and the imaging elements on the image-side end face of the lens barrel within an optimal range while ensuring that the optical imaging system has a large f-number, thereby improving the assembly yield and product competitiveness of the optical imaging system.

[0051] In an exemplary embodiment, the total effective focal length f of the optical imaging system, half of the maximum field angle of the optical imaging system Semi-FOV, and the length L of the lens barrel in the direction of the optical axis can satisfy: 55mm 2 < f / tan(Semi-FOV) × L < 95mm 2 . In an example, 60mm 2 < f / tan(Semi-FOV) × L < 85mm 2 . By controlling the relationship between the total effective focal length of the optical imaging system, half of the maximum field angle of the optical imaging system, and the length of the lens barrel in the direction of the optical axis, it is possible to ensure that the overall optical length of the optical imaging system is in the minimum state, thereby reducing the size of the module and the whole machine.

[0052] In an exemplary embodiment, the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the inner diameter d1s of the object-side face of the first spacer element, and the outer diameter D1m of the image-side face of the first spacer element can satisfy: -25 < (f2 - f1) / (D1m - d1s) < -4. In an example, -21 < (f2 - f1) / (D1m - d1s) < -8. By controlling the relationship between the effective focal lengths of the first lens and the second lens and the inner diameter of the object-side face and the outer diameter of the image-side face of the first spacer element, it is possible to ensure that the light passing through the first lens does not generate too much stray light when passing through the first spacer element and does not affect the refraction of normal light, thereby improving the overall quality of the optical imaging system.

[0053] In an exemplary embodiment, the optical imaging system may further satisfy: R2 / R1>1, R4 / R3>0, R6 / R5>0, where R1 is the radius of curvature of the object side surface of the first lens, R2 is the radius of curvature of the image side surface of the first lens, R3 is the radius of curvature of the object side surface of the second lens, R4 is the radius of curvature of the image side surface of the second lens, R5 is the radius of curvature of the object side surface of the third lens, and R6 is the radius of curvature of the image side surface of the third lens. By controlling the radii of curvature of the object side and image side surfaces of the first lens to the third lens, it is possible to ensure that the light converges after passing through the first lens, and to ensure that the quality of the light after passing through the second lens and the third lens is relatively high, thereby improving the imaging quality of the optical imaging system.

[0054] In an exemplary embodiment, the radius of curvature R2 of the image side surface of the first lens, the radius of curvature R3 of the object side surface of the second lens, the radius of curvature R4 of the image side surface of the second lens, the radius of curvature R5 of the object side surface of the third lens, the axial spacing EP12 between the first spacer element and the second spacer element, and the axial spacing EP23 between the second spacer element and the third spacer element may satisfy: 30 < (R2 - R3) / EP12 + (R5 - R4) / EP23 < 60. In an example, 35 < (R2 - R3) / EP12 + (R5 - R4) / EP23 < 55. By controlling the sum of the ratios of the radii of curvature of the relevant surfaces of the first lens to the third lens to the on-axis distances of the adjacent spacer elements, it is effectively ensured that the light passing through the imaging element group composed of the first lens to the third lens can be transmitted within a certain radius range, reducing the generation of stray light and improving the imaging quality of the optical imaging system.

[0055] In an exemplary embodiment, the effective focal length f4 of the fourth lens, the effective focal length f5 of the fifth lens, the inner diameter d4s of the object side surface of the fourth spacer element, and the outer diameter D4s of the object side surface of the fourth spacer element may satisfy: -28 < f4 / d4s + f5 / D4s < -1. In an example, -24 < f4 / d4s + f5 / D4s < -5. By controlling the sum of the ratio of the effective focal length of the fourth lens to the inner diameter of the object side surface of the fourth spacer element and the ratio of the effective focal length of the fifth lens to the outer diameter of the object side surface of the fourth spacer element, it is possible to ensure that the light passing through the fourth lens will neither generate excessive stray light when passing through the fourth spacer element nor affect the refraction of normal light, thereby improving the overall quality of the optical imaging system.

[0056] In an exemplary embodiment, the radius of curvature R12 of the image side surface of the sixth lens, the radius of curvature R13 of the object side surface of the seventh lens, the inner diameter d6m of the image side surface of the sixth spacer element, and the outer diameter D6m of the image side surface of the sixth spacer element may satisfy: 6 mm < (R13 - R12) / d6m × D6m < 30 mm. In an example, 10 mm < (R13 - R12) / d6m × D6m < 25 mm. By controlling the relationship between the difference in the radius of curvature of the adjacent surfaces of the sixth lens and the seventh lens and the inner and outer diameters of the image side surface of the sixth spacer element, it is possible to ensure that the light is within a reasonable radius range when passing through the seventh lens, so as to meet the final imaging height and improve the specification quality of the optical imaging system.

[0057] In an exemplary embodiment, the effective focal length f5 of the fifth lens, the effective focal length f6 of the sixth lens, the inner diameter d5m of the image side surface of the fifth spacer element, and the outer diameter D5m of the image side surface of the fifth spacer element may satisfy: 26 < (f5 × f6) / (D5m × d5m) < 66. By controlling the product of the ratio of the effective focal length of the fifth lens to the inner diameter of the image side surface of the fifth spacer element and the ratio of the effective focal length of the sixth lens to the inner diameter of the image side surface of the fifth spacer element, it is possible to ensure that the light flux loss when the light passing through the fifth lens passes through the fifth spacer element is within a reasonable range, thereby ensuring the performance index of the optical imaging system.

[0058] In an exemplary embodiment, the central thickness CT3 of the third lens on the optical axis, the outer diameter D3m of the image side surface of the third spacer element, the outer diameter D4m of the image side surface of the fourth spacer element, and the maximum thickness CP4 of the fourth spacer element may satisfy: -17 < D4m / CP4 - D3m / CT3 < 0. In an example, -12 < D4m / CP4 - D3m / CT3 < -2. By controlling the difference between the ratio of the outer diameter of the image side surface of the fourth spacer element to the maximum thickness of the fourth spacer element and the ratio of the outer diameter of the image side surface of the third spacer element to the central thickness of the third lens on the optical axis, it is possible to ensure that the imaging element group formed by the third lens, the fourth lens, the third spacer element, and the fourth spacer element has the most reasonable outer diameter difference, effectively improving the assembly yield and reliability of the optical imaging system during the production process.

[0059] In an exemplary embodiment, the optical imaging system may further satisfy: 0 < fi / dis < 7, where i = 1, 4, or 7. When i = 1, fi represents the effective focal length of the first lens, and dis represents the inner diameter of the object side surface of the first spacer element; when i = 4, fi represents the effective focal length of the fourth lens, and dis represents the inner diameter of the object side surface of the fourth spacer element; when i = 7, fi represents the effective focal length of the seventh lens, and dis represents the inner diameter of the object side surface of the seventh spacer element. By controlling the ratio of the effective focal length of each lens with positive optical power to the outer diameter of the object side surface of the spacer element at its image side surface, the divergence height of the light rays after passing through each positive lens can be ensured to be within a reasonable range, thereby improving the reliability of the optical imaging system.

[0060] In an exemplary embodiment, the axial spacing EP45 between the fourth spacer element and the fifth spacer element, the air spacing T56 between the fifth lens and the sixth lens on the optical axis, the radius of curvature R8 of the image side surface of the fourth lens, and the radius of curvature R11 of the object side surface of the sixth lens may satisfy: 0 < (T56 / EP45) × (R8 / R11) < 9. By controlling the relationship between the axial distance between the fourth spacer element and the fifth spacer element and the relevant parameters of the adjacent fourth lens, fifth lens, and sixth lens, the structural uniformity of the fourth lens, fifth lens, and sixth lens can be ensured, which is beneficial to the processing and shaping of each lens, thereby improving the performance and mass production yield of the optical imaging system.

[0061] In an exemplary embodiment, the refractive indices of the second lens and the fifth lens are greater than 1.60, and the optical imaging system may further satisfy: EP12 > T12, EP45 < T45, where EP12 is the axial spacing between the first spacer element and the second spacer element, T12 is the air spacing between the first lens and the second lens on the optical axis, EP45 is the axial spacing between the fourth spacer element and the fifth spacer element, and T45 is the air spacing between the fourth lens and the fifth lens on the optical axis. By controlling the relationship between the relevant axial distances of the second lens and the fifth lens and the axial distances of the adjacent spacer elements, it can be ensured that the light rays can converge quickly when passing through the first lens and the second lens, and can diverge and refract quickly when passing through the fourth lens and the fifth lens, ensuring the imaging convergence of the light rays, thereby improving the performance of the optical imaging system.

[0062] In an exemplary embodiment, the effective focal length f6 of the sixth lens, the effective focal length f7 of the seventh lens, the effective focal length f8 of the eighth lens, the maximum thickness CP6 of the sixth spacer element, the maximum thickness CP7 of the seventh spacer element, and the spacing EP67 of the sixth and seventh spacers along the optical axis can satisfy: -30 < (f6 + f7 + f8) / (CP6 + EP67 + CP7) < -6. In the example, -25 < (f6 + f7 + f8) / (CP6 + EP67 + CP7) < -12. By controlling the relationship between the sum of the effective focal lengths of the sixth to eighth lenses and the axial dimensions of the relevant spacers, the axial and radial stability of the imaging element group formed by the sixth to eighth lenses is ensured, thereby improving the assembly yield of the optical imaging system.

[0063] In an exemplary embodiment, the outer diameter D0s of the object-side end face of the lens barrel, the outer diameter D0m of the image-side end face of the lens barrel, the total effective focal length f of the optical imaging system, and the effective focal length f8 of the eighth lens can satisfy: -17 < (D0m - D0s) / f × f8 < -4. By controlling the relationship between the difference in outer diameters of the object and image-side end faces of the lens barrel and the total effective focal length of the optical imaging system and the effective focal length of the eighth lens, the size of the image-side end face of the lens barrel can be minimized. This ensures that the volume and size of the optical imaging system are minimized while maintaining its optical performance, thereby enhancing the competitiveness of the optical imaging system.

[0064] In an exemplary embodiment, the optical imaging system further includes an aperture stop, which can be disposed between the object side and the first lens as needed.

[0065] The optical imaging system according to the above embodiments of this application can employ eight lenses and multiple spacer elements. By rationally allocating the parameters of each lens and each spacer element, the optical imaging system can have a smaller size, reduce stray light, and improve the assembly yield, reliability, and imaging quality of the optical imaging system.

[0066] In embodiments of this application, at least one of the mirror surfaces of the first to eighth lenses is an aspherical mirror surface. An aspherical lens is characterized by a continuously changing curvature from the lens center to the lens periphery. Unlike a spherical lens, which has a constant curvature from the lens center to the lens periphery, an aspherical lens has better radius of curvature characteristics, offering advantages in improving distortion aberrations and astigmatism. By using an aspherical lens, aberrations occurring during imaging can be eliminated as much as possible, thereby improving image quality. Optionally, both the object-side and image-side surfaces of the first to eighth lenses are aspherical mirror surfaces.

[0067] However, those skilled in the art should understand that, without departing from the technical solutions claimed in this application, the number of lenses and spacers constituting the optical imaging system can be changed to obtain the various results and advantages described in this specification.

[0068] Specific embodiments of the optical imaging system applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

[0069] First embodiment

[0070] The following is for reference Figures 2 to 5D An optical imaging system according to a first embodiment of this application is described. Figure 2 A schematic diagram of the structure of an optical imaging system 110 according to Embodiment 1 of the first embodiment of this application is shown; Figure 3 A schematic diagram of the structure of an optical imaging system 120 according to Embodiment 2 of the first embodiment of this application is shown; Figure 4 A schematic diagram of the structure of an optical imaging system 130 according to Embodiment 3 of the first embodiment of this application is shown.

[0071] like Figures 2 to 4 As shown, optical imaging systems 110, 120, and 130 all include a lens barrel and an eight-element lens group and a spacer element group housed within the lens barrel. The eight-element lens group, from the object side to the image side, includes, in sequence: a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, and an eighth lens E8. An aperture stop STO can be positioned between the object side and the first lens E1 as needed. The spacer element group includes: a first spacer element P1, a second spacer element P2, a third spacer element P3, a fourth spacer element P4, a fifth spacer element P5, a sixth spacer element P6, and a seventh spacer element P7. The spacers prevent excess light from entering the next lens during the imaging process, allowing for better contact between the lens and the lens barrel, thus enhancing the structural stability of the optical imaging system.

[0072] The first lens E1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens E2 has negative optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens E3 has negative optical power, with its object-side surface S5 being convex and its image-side surface S6 being concave. The fourth lens E4 has positive optical power, with its object-side surface S7 being convex and its image-side surface S8 being convex. The fifth lens E5 has negative optical power, with its object-side surface S9 being convex and its image-side surface S10 being concave. The sixth lens E6 has negative optical power, with its object-side surface S11 being concave and its image-side surface S12 being convex. The seventh lens E7 has positive optical power, with its object-side surface S13 being convex and its image-side surface S14 being concave. The eighth lens E8 has negative optical power, with its object-side surface S15 being convex and its image-side surface S16 being concave. The filter has an object-side surface S17 (not shown) and an image-side surface S18 (not shown). Light from the object passes sequentially through each surface S1 to S18 and is finally imaged on the imaging surface.

[0073] Table 1 shows the basic parameters of the optical imaging system of the first embodiment, where the units for radius of curvature, thickness / distance, and focal length are all millimeters (mm).

[0074]

[0075] Table 1

[0076] In this embodiment, the total effective focal length f of the optical imaging system is 7.5515 mm, the value of half of the maximum field of view (Semi-FOV) of the optical imaging system is 41.9883°, and the value of the aperture number (FNO) of the optical imaging system is 1.8317.

[0077] In the first embodiment, the object-side surface and image-side surface of any one of the first lens E1 to the eighth lens E8 are aspherical surfaces, and the surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0078]

[0079] Where x is the distance vector from the vertex of the aspherical surface at a height of h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., 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 gives the higher-order coefficients A4, A6, A8, A16, A26, A36, A47, A68, A166 that can be used for each aspherical mirror S1-S16 in the first embodiment. 10 A 12 A 14 A 16 A 18 and A 20 .

[0080]

[0081]

[0082] Table 2

[0083] Figure 5A The on-axis chromatic aberration curves of the optical imaging systems 110, 120 and 130 of the first embodiment are shown, which represent the deflection of the focal point after light of different wavelengths passes through the optical imaging systems 110, 120 and 130. Figure 5B Astigmatism curves of the optical imaging systems 110, 120, and 130 of the first embodiment are shown, representing the meridional and sagittal image plane curvatures corresponding to different image heights. Figure 5C The distortion curves of the optical imaging systems 110, 120 and 130 of the first embodiment are shown, which represent the distortion magnitude values ​​corresponding to different image heights. Figure 5D The magnification chromatic aberration curves of the optical imaging systems 110, 120, and 130 of the first embodiment are shown, representing the deviations in image height at different points on the imaging plane after light passes through the system. According to... Figures 5A to 5D It can be seen that the optical imaging systems 110, 120 and 130 given in the first embodiment can achieve good imaging quality.

[0084] Second embodiment

[0085] The following is for reference Figures 6 to 9D An optical imaging system according to a second embodiment of this application is described. Figure 6 A schematic diagram of the structure of an optical imaging system 210 according to Embodiment 1 of the second embodiment of this application is shown; Figure 7 A schematic diagram of the structure of an optical imaging system 220 according to Embodiment 2 of the second embodiment of this application is shown; Figure 8 A schematic diagram of the structure of an optical imaging system 230 according to Embodiment 3 of the second embodiment of this application is shown.

[0086] like Figures 6 to 8As shown, optical imaging systems 210, 220, and 230 all include a lens barrel and an eight-lens group and a spacer group housed within the lens barrel. The eight-lens group, from the object side to the image side, includes: a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, and an eighth lens E8. An aperture stop STO can be positioned between the object side and the first lens E1 as needed. The spacer group includes: a first spacer P1, a second spacer P2, a third spacer P3, a fourth spacer P4, a fifth spacer P5, a sixth spacer P6, and a seventh spacer P7. The spacers prevent excess light from entering the next lens during the imaging process, allowing for better contact between the lens and the lens barrel, thus enhancing the structural stability of the optical imaging system.

[0087] The first lens E1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens E2 has negative optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens E3 has negative optical power, with its object-side surface S5 being convex and its image-side surface S6 being concave. The fourth lens E4 has positive optical power, with its object-side surface S7 being convex and its image-side surface S8 being convex. The fifth lens E5 has negative optical power, with its object-side surface S9 being convex and its image-side surface S10 being concave. The sixth lens E6 has negative optical power, with its object-side surface S11 being concave and its image-side surface S12 being convex. The seventh lens E7 has positive optical power, with its object-side surface S13 being convex and its image-side surface S14 being convex. The eighth lens E8 has negative optical power, with its object-side surface S15 being convex and its image-side surface S16 being concave. The filter has an object-side surface S17 (not shown) and an image-side surface S18 (not shown). Light from the object passes sequentially through each surface S1 to S18 and is finally imaged on the imaging surface.

[0088] Table 3 shows the basic parameters of the optical imaging system of the second embodiment, where the units for radius of curvature, thickness / distance, and focal length are all millimeters (mm).

[0089]

[0090]

[0091] In this embodiment, the total effective focal length f of the optical imaging system is 6.8067 mm, the value of half of the maximum field of view (Semi-FOV) of the optical imaging system is 40.6815°, and the value of the aperture number (FNO) of the optical imaging system is 1.8317.

[0092] In the second embodiment, the object-side surface and image-side surface of any one of the first lens E1 to the eighth lens E8 are aspherical. Table 4 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for each aspherical mirror S1-S16 in the second embodiment. 10 A 12 A 14 A 16 A 18 and A 20 .

[0093]

[0094] Table 4

[0095] Figure 9A The on-axis chromatic aberration curves of the optical imaging systems 210, 220 and 230 of the second embodiment are shown, which represent the deflection of the focal point after light of different wavelengths passes through the optical imaging systems 210, 220 and 230. Figure 9B Astigmatism curves of optical imaging systems 210, 220, and 230 according to the second embodiment are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different image heights. Figure 9C The distortion curves of the optical imaging systems 210, 220 and 230 of the second embodiment are shown, which represent the distortion magnitude values ​​corresponding to different image heights. Figure 9D The magnification chromatic aberration curves of the optical imaging systems 210, 220, and 230 of the second embodiment are shown, representing the deviations in image height at different points on the imaging plane after light passes through the system. According to Figures 9A to 9D It can be seen that the optical imaging systems 210, 220 and 230 of the second embodiment can achieve good imaging quality.

[0096] Third embodiment

[0097] The following is for reference Figures 10 to 13D This application describes an optical imaging system according to a third embodiment. Figure 10 A schematic diagram of the structure of an optical imaging system 310 according to Embodiment 1 of the third embodiment of this application is shown; Figure 11 A schematic diagram of the structure of an optical imaging system 320 according to Embodiment 2 of the third embodiment of this application is shown; Figure 12 A schematic diagram of the structure of an optical imaging system 330 according to Embodiment 3 of the third embodiment of this application is shown.

[0098] like Figures 10 to 12As shown, optical imaging systems 310, 320, and 330 all include a lens barrel and an eight-lens group and a spacer group housed within the lens barrel. The eight-lens group, from the object side to the image side, includes, in sequence: a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, and an eighth lens E8. An aperture stop STO can be positioned between the object side and the first lens E1 as needed. The spacer group includes: a first spacer P1, a second spacer P2, a third spacer P3, a fourth spacer P4, a fifth spacer P5, a sixth spacer P6, and a seventh spacer P7. The spacers prevent excess light from entering the next lens during the imaging process, allowing for better contact between the lens and the lens barrel, thus enhancing the structural stability of the optical imaging system.

[0099] The first lens E1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens E2 has negative optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens E3 has negative optical power, with its object-side surface S5 being convex and its image-side surface S6 being concave. The fourth lens E4 has positive optical power, with its object-side surface S7 being convex and its image-side surface S8 being convex. The fifth lens E5 has negative optical power, with its object-side surface S9 being concave and its image-side surface S10 being convex. The sixth lens E6 has negative optical power, with its object-side surface S11 being concave and its image-side surface S12 being convex. The seventh lens E7 has positive optical power, with its object-side surface S13 being convex and its image-side surface S14 being concave. The eighth lens E8 has negative optical power, with its object-side surface S15 being convex and its image-side surface S16 being concave. The filter has an object-side surface S17 (not shown) and an image-side surface S18 (not shown). Light from the object passes sequentially through each surface S1 to S18 and is finally imaged on the imaging surface.

[0100] Table 5 shows the basic parameters of the optical imaging system of the third embodiment, where the units for radius of curvature, thickness / distance, and focal length are all millimeters (mm).

[0101]

[0102]

[0103] Table 5

[0104] In this embodiment, the total effective focal length f of the optical imaging system is 8.3206 mm, the value of half of the maximum field of view (Semi-FOV) of the optical imaging system is 41.6700°, and the value of the aperture number (FNO) of the optical imaging system is 1.8317.

[0105] In the third embodiment, the object-side surface and image-side surface of any one of the first lens E1 to the eighth lens E8 are aspherical. Table 6 gives the higher-order coefficients A4, A6, A8, and A6 that can be used for each aspherical mirror S1-S16 in the third embodiment. 10 A 12 A 14 A 16 A 18 and A 20 .

[0106]

[0107]

[0108] Table 6

[0109] Figure 13A The on-axis chromatic aberration curves of the optical imaging systems 310, 320 and 330 of the third embodiment are shown, which represent the deflection of the focal point after light of different wavelengths passes through the optical imaging systems 310, 320 and 330. Figure 13B Astigmatism curves of optical imaging systems 310, 320, and 330 according to the third embodiment are shown, representing the meridional and sagittal image plane curvatures corresponding to different image heights. Figure 13C The distortion curves of the optical imaging systems 310, 320 and 330 of the third embodiment are shown, which represent the distortion magnitude values ​​corresponding to different image heights. Figure 13D The magnification chromatic aberration curves of the optical imaging systems 310, 320, and 330 of the third embodiment are shown, representing the deviations in image height at different points on the imaging plane after light passes through the system. According to Figures 13A to 13D It can be seen that the optical imaging systems 310, 320 and 330 of the third embodiment can achieve good imaging quality.

[0110] Table 7 lists some basic parameters of the lens barrel and spacer element in each embodiment from the first to the third embodiment, such as d1s, D1s, D1m, D3m, d4s, D4s, D4m, d5m, D5m, d6m, D6m, d7s, d7m, D7m, d0s, D0s, D0m, EP12, EP23, CP4, EP45, CP6, EP67, CP7, and L. The basic parameters listed in Table 7 are based on... Figure 1 The measurements were obtained using the annotation method shown, and the units of the basic parameters listed in Table 7 are all millimeters (mm).

[0111]

[0112]

[0113] Table 7

[0114] In summary, the conditional expressions of each embodiment in the first to third embodiments satisfy the relationships shown in Table 8.

[0115]

[0116] Table 8

[0117] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An optical imaging system, characterized in that, include: An eight-element lens group, comprising elements arranged sequentially along the optical axis from the object side to the image side: The first lens with positive optical power has an object-side surface that is convex at the paraxial direction and an image-side surface that is concave at the paraxial direction. The second lens with negative optical power has an object-side surface that is convex near the axis and an image-side surface that is concave near the axis. A third lens with negative optical power has an object-side surface that is convex near the axis and an image-side surface that is concave near the axis. The fourth lens with positive optical power has an object-side surface that is convex at the paraxial direction and an image-side surface that is convex at the paraxial direction. A fifth lens with negative optical power; The sixth lens with negative optical power has an object-side surface that is concave near the axis and an image-side surface that is convex near the axis. A seventh lens with positive optical power, the object-side surface of which is convex near the axis; and The eighth lens with negative optical power has an object-side surface that is convex near the axis and an image-side surface that is concave near the axis. The spacer group includes a seventh spacer element that is placed on the image-side surface of the seventh lens and in contact with the image-side surface of the seventh lens; as well as The lens barrel, the eight-element lens group, and the spacer element group are placed inside the lens barrel. The optical imaging system has eight lenses with optical power. The radius of curvature R15 of the object-side surface of the eighth lens, the radius of curvature R16 of the image-side surface of the eighth lens, the inner diameter d7m of the image-side surface of the seventh spacer element, and the outer diameter D7m of the image-side surface of the seventh spacer element satisfy: 8.47≤D7m / R16+d7m / R15≤12.05, and The effective focal length f7 of the seventh lens, the effective focal length f8 of the eighth lens, the center thickness CT8 of the eighth lens on the optical axis and the maximum thickness CP7 of the seventh spacer element satisfy: -38.70≤f8 / (CT8-CP7)-f7(CT8+CP7)≤-13.

67.

2. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a first spacer element disposed on and in contact with the image-side surface of the first lens. Wherein, the inner diameter d0s of the object-side end face of the lens barrel, the outer diameter D1s of the object-side end face of the first spacer element, and the aperture number FNO of the optical imaging system satisfy: 12.65≤d0s×D1s / FNO≤20.

33.

3. The optical imaging system according to claim 1, characterized in that, The total effective focal length f of the optical imaging system, half of the maximum field of view (Semi-FOV) of the optical imaging system, and the length L of the lens barrel along the optical axis satisfy the following condition: 65.52 mm. 2 ≤f / tan(Semi-FOV)×L≤84.04mm 2 .

4. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a first spacer element disposed on and in contact with the image-side surface of the first lens. Wherein, the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the inner diameter d1s of the object side of the first spacer element and the outer diameter D1m of the image side of the first spacer element satisfy: -20.17≤(f2-f1) / (D1m-d1s)≤-9.

11.

5. The optical imaging system according to claim 1, characterized in that, The optical imaging system also satisfies: 5.12≤R2 / R1≤7.56, 0.54≤R4 / R3≤0.63, 0.83≤R6 / R5≤0.96 Wherein, R1 is the radius of curvature of the object side of the first lens, R2 is the radius of curvature of the image side of the first lens, R3 is the radius of curvature of the object side of the second lens, R4 is the radius of curvature of the image side of the second lens, R5 is the radius of curvature of the object side of the third lens, and R6 is the radius of curvature of the image side of the third lens.

6. The optical imaging system according to claim 5, characterized in that, The spacer element group further includes a first spacer element, a second spacer element, and a third spacer element. The first spacer element is positioned on and in contact with the image-side surface of the first lens. The second spacer element is positioned on and in contact with the image-side surface of the second lens. The third spacer element is positioned on and in contact with the image-side surface of the third lens. Wherein, the radius of curvature R2 of the image side of the first lens, the radius of curvature R3 of the object side of the second lens, the radius of curvature R4 of the image side of the second lens, the radius of curvature R5 of the object side of the third lens, the spacing EP12 of the first and second spacers along the optical axis and the spacing EP23 of the second and third spacers along the optical axis satisfy: 36.77≤(R2-R3) / EP12+(R5-R4) / EP23≤52.

50.

7. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a fourth spacer element disposed on and in contact with the image-side surface of the fourth lens. Wherein, the effective focal length f4 of the fourth lens, the effective focal length f5 of the fifth lens, the inner diameter d4s of the object side of the fourth spacer element and the outer diameter D4s of the object side of the fourth spacer element satisfy: -23.07≤f4 / d4s+f5 / D4s≤-5.

20.

8. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a sixth spacer element disposed on and in contact with the image-side surface of the sixth lens. The radius of curvature R12 of the image side of the sixth lens, the radius of curvature R13 of the object side of the seventh lens, the inner diameter d6m of the image side of the sixth spacer element, and the outer diameter D6m of the image side of the sixth spacer element satisfy the following: 12.86mm≤(R13-R12) / d6m×D6m≤24.04mm.

9. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a fifth spacer element disposed on and in contact with the image-side surface of the fifth lens. Wherein, the effective focal length f5 of the fifth lens, the effective focal length f6 of the sixth lens, the inner diameter d5m of the image side of the fifth spacer element and the outer diameter D5m of the image side of the fifth spacer element satisfy: 32.12≤(f5×f6) / (D5m×d5m)≤60.

32.

10. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a third spacer element and a fourth spacer element. The third spacer element is positioned on and in contact with the image-side surface of the third lens, and the fourth spacer element is positioned on and in contact with the image-side surface of the fourth lens. Wherein, the center thickness CT3 of the third lens on the optical axis, the outer diameter D3m of the image side of the third spacer element, the outer diameter D4m of the image side of the fourth spacer element, and the maximum thickness CP4 of the fourth spacer element satisfy: -11.29≤D4m / CP4-D3m / CT3≤-2.

49.

11. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a first spacer element and a fourth spacer element. The first spacer element is positioned on the image-side surface of the first lens and contacts the image-side surface of the first lens. The fourth spacer element is positioned on the image-side surface of the fourth lens and contacts the image-side surface of the fourth lens. The optical imaging system also satisfies: 0.83 ≤ fi / dis ≤ 4.35, i = 1, 4, or 7. Where i is 1, fi represents the effective focal length of the first lens, and dis represents the inner diameter of the object side of the first spacer element; when i is 4, fi represents the effective focal length of the fourth lens, and dis represents the inner diameter of the object side of the fourth spacer element; when i is 7, fi represents the effective focal length of the seventh lens, and dis represents the inner diameter of the object side of the seventh spacer element.

12. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a fourth spacer element and a fifth spacer element. The fourth spacer element is positioned on the image-side surface of the fourth lens and is in contact with the image-side surface of the fourth lens. The fifth spacer element is positioned on the image-side surface of the fifth lens and is in contact with the image-side surface of the fifth lens. Wherein, the spacing EP45 between the fourth and fifth spacers along the optical axis, the air spacing T56 between the fifth and sixth lenses on the optical axis, and the radius of curvature R8 of the image side of the fourth lens and the radius of curvature R11 of the object side of the sixth lens satisfy: 3.82≤(T56 / EP45)×(R8 / R11)≤5.

19.

13. The optical imaging system according to claim 12, characterized in that, The spacer element group further includes a first spacer element and a second spacer element. The first spacer element is positioned on the image-side surface of the first lens and contacts the image-side surface of the first lens. The second spacer element is positioned on the image-side surface of the second lens and contacts the image-side surface of the second lens. The second and fifth lenses have refractive indices greater than 1.60, and the optical imaging system also satisfies: EP12 > T12, EP45 <T45, Wherein, EP12 is the spacing between the first spacer element and the second spacer element along the optical axis, T12 is the air gap between the first lens and the second lens on the optical axis, EP45 is the spacing between the fourth spacer element and the fifth spacer element along the optical axis, and T45 is the air gap between the fourth lens and the fifth lens on the optical axis.

14. The optical imaging system according to claim 1, characterized in that, The spacer element group further includes a sixth spacer element disposed on and in contact with the image-side surface of the sixth lens. Wherein, the effective focal length f6 of the sixth lens, the effective focal length f7 of the seventh lens, the effective focal length f8 of the eighth lens, the maximum thickness CP6 of the sixth spacer element, the maximum thickness CP7 of the seventh spacer element, and the spacing EP67 of the sixth and seventh spacers along the optical axis satisfy: -23.22≤(f6+f7+f8) / (CP6+EP67+CP7)≤-12.

91.

15. The optical imaging system according to any one of claims 1 to 14, characterized in that, The outer diameter D0s of the object-side end face of the lens barrel, the outer diameter D0m of the image-side end face of the lens barrel, the total effective focal length f of the optical imaging system and the effective focal length f8 of the eighth lens satisfy: -14.42≤(D0m-D0s) / f×f8≤-7.87.

Images