Optical image capturing system

Abstract

The utility model provides an optical imaging system. The optical imaging system comprises a lens barrel, a lens group and a spacing element group, wherein the lens group and the spacing element group are arranged in the lens barrel. The lens group is composed of eight lenses. The following conditions are satisfied: 4.50 lt; t45 / CP4lt, T45 / CP4lt; 20.98, 20.98; the following conditions are satisfied: 3.21 lt; d4m / CT5lt; and 4.81. According to the utility model, the problems that the eight-piece optical imaging system in the prior art restrains the optical parameters of the middle lens to meet the requirement of high optical performance, so that the size of the middle lens is not uniform, the stress is too large after the middle lens is assembled, and the assembling reliability is influenced are solved.

Description

Technical Field

[0001] This utility model relates to the field of optical imaging equipment technology, and more specifically, to an optical imaging system. Background Technology

[0002] With advancements in optical design and manufacturing processes, manufacturers are demanding increasingly higher optical performance and reliability from optical imaging systems. Eight-element optical imaging systems, due to their balance of high optical performance and reliability, are widely used in mobile phone cameras, high-end video recording, medical imaging, and industrial inspection. However, designing eight-element optical imaging systems presents numerous challenges in achieving both high optical performance and high reliability.

[0003] Currently, eight-element optical imaging systems typically require constraints on the optical parameters of the central lens to achieve high optical performance, particularly its center thickness and optical power, in order to correct aberrations and ensure image quality. However, this can easily lead to uneven thickness of the central lens, increasing stress on it after assembly. Increased stress can cause lens deformation, reducing assembly reliability and severely impacting the overall reliability of the optical imaging system.

[0004] In other words, the existing eight-element optical imaging system has the problem of constraining the optical parameters of the central lens to meet the requirements of high optical performance, resulting in uneven size of the central lens, which in turn leads to excessive stress after the central lens is assembled, affecting the reliability of the assembly. Utility Model Content

[0005] The main objective of this invention is to provide an optical imaging system that addresses the problem in existing eight-element optical imaging systems where the optical parameters of the central lens are constrained to meet high optical performance requirements, resulting in uneven size of the central lens and excessive stress after assembly, thus affecting assembly reliability.

[0006] To achieve the above object, according to one aspect of the present invention, an optical imaging system is provided, which includes a lens barrel and a lens group and a spacer element group disposed in the lens barrel. The lens group consists of eight lenses. The eight lenses are, in order from the object side to the image side, a first lens with a positive or negative optical power, a second lens with a negative optical power, a third lens with a positive optical power, a fourth lens with a negative optical power, a fifth lens with a positive optical power, a sixth lens with a negative optical power, a seventh lens with a positive optical power, and an eighth lens with a negative optical power. Among the first lens to the eighth lens, the fifth lens has the largest central thickness on the optical axis of the optical imaging system. The spacer element group includes a first spacer element disposed between the first lens and the second lens and partially contacting the image side surface of the first lens, a second spacer element disposed between the second lens and the third lens and partially contacting the image side surface of the second lens, a third spacer element disposed between the third lens and the fourth lens and partially contacting the image side surface of the third lens, a fourth spacer element disposed between the fourth lens and the fifth lens and partially contacting the image side surface of the fourth lens, a fifth spacer element disposed between the fifth lens and the sixth lens and partially contacting the image side surface of the fifth lens, a sixth spacer element disposed between the sixth lens and the seventh lens and partially contacting the image side surface of the sixth lens, and a seventh spacer element disposed between the seventh lens and the eighth lens and partially contacting the image side surface of the seventh lens. Among them, the air gap T45 between the fourth lens and the fifth lens on the optical axis and the maximum axial thickness CP4 of the fourth spacer element satisfy: 4.50 < T45 / CP4 < 20.98; the inner diameter d4m of the image side surface of the fourth spacer element and the central thickness CT5 of the fifth lens on the optical axis satisfy: 3.21 < d4m / CT5 < 4.81.

[0007] According to another aspect of the present utility model, an optical imaging system is provided, which includes a lens barrel and a lens group and a spacer element group disposed in the lens barrel. The lens group consists of eight lenses. The eight lenses are, in order from the object side to the image side, a first lens having a positive or negative optical power, a second lens having a negative optical power, a third lens having a positive optical power, a fourth lens having a negative optical power, a fifth lens having a positive optical power, a sixth lens having a negative optical power, a seventh lens having a positive optical power, and an eighth lens having a negative optical power; among the first lens to the eighth lens, the fifth lens has the largest central thickness on the optical axis of the optical imaging system; the spacer element group includes a first spacer element disposed between the first lens and the second lens and partially contacting the image side surface of the first lens, a second spacer element disposed between the second lens and the third lens and partially contacting the image side surface of the second lens, a third spacer element disposed between the third lens and the fourth lens and partially contacting the image side surface of the third lens, a fourth spacer element disposed between the fourth lens and the fifth lens and partially contacting the image side surface of the fourth lens, a fifth spacer element disposed between the fifth lens and the sixth lens and partially contacting the image side surface of the fifth lens, a sixth spacer element disposed between the sixth lens and the seventh lens and partially contacting the image side surface of the sixth lens, and a seventh spacer element disposed between the seventh lens and the eighth lens and partially contacting the image side surface of the seventh lens; wherein, the inner diameter d 4m of the image side surface of the fourth spacer element and the central thickness CT 5 of the fifth lens on the optical axis satisfy: 3.21 < d [4m] / CT [5] < 4.81. The axial distance SAG

[42] between the intersection point of the image side surface of the fourth lens and the optical axis and the vertex of the effective radius of the image side surface of the fourth lens and the maximum axial thickness CP [4]) of the fourth spacer element satisfy: 11.71 < SAG

[42] / CP [4] < 22.19.

[0008] According to another aspect of the present utility model, an optical imaging system is provided, which includes a lens barrel and a lens group and a spacer element group disposed in the lens barrel. The lens group consists of eight lenses. The eight lenses are, in order from the object side to the image side, a first lens having a positive or negative optical power, a second lens having a negative optical power, a third lens having a positive optical power, a fourth lens having a negative optical power, a fifth lens having a positive optical power, a sixth lens having a negative optical power, a seventh lens having a positive optical power, and an eighth lens having a negative optical power; among the first lens to the eighth lens, the fifth lens has the largest central thickness on the optical axis of the optical imaging system; the spacer element group includes a first spacer element disposed between the first lens and the second lens and in partial contact with the image side surface of the first lens, a second spacer element disposed between the second lens and the third lens and in partial contact with the image side surface of the second lens, a third spacer element disposed between the third lens and the fourth lens and in partial contact with the image side surface of the third lens, a fourth spacer element disposed between the fourth lens and the fifth lens and in partial contact with the image side surface of the fourth lens, a fifth spacer element disposed between the fifth lens and the sixth lens and in partial contact with the image side surface of the fifth lens, a sixth spacer element disposed between the sixth lens and the seventh lens and in partial contact with the image side surface of the sixth lens, and a seventh spacer element disposed between the seventh lens and the eighth lens and in partial contact with the image side surface of the seventh lens; wherein, the effective focal length f4 of the fourth lens and the central thickness CT5 of the fifth lens on the optical axis satisfy: 4.90 < f4 / CT5 < 6.30; the inner diameter d4m of the image side surface of the fourth spacer element, the maximum axial thickness CP4 of the fourth spacer element, and the air gap T45 between the fourth lens and the fifth lens on the optical axis satisfy: 10.20 < d4m / (CP4 + T45) < 38.26.

[0009] Further, the effective focal length f4 of the fourth lens and the curvature radius R7 of the object side surface of the fourth lens satisfy: -4.85 < f4 / R7 < -1.62; the effective focal length f4 of the fourth lens and the inner diameter d3m of the image side surface of the third spacer element satisfy: -4.98 < f*4 / d3m < -2.27.

[0010] Further, the air gap T67 between the sixth lens and the seventh lens on the optical axis, the air gap T78 between the seventh lens and the eighth lens on the optical axis, and the interval distance EP67 on the optical axis from the image side surface of the sixth spacer element to the object side surface of the seventh spacer element satisfy: 0.44 < EP67 / (T78 - T67) < 3.11.

[0011] Further, among the adjacent two lenses of the first lens to the eighth lens, the air gap between the seventh lens and the eighth lens on the optical axis is the largest, and the inner diameter d7m of the image side surface of the seventh spacer element and the air gap T78 between the seventh lens and the eighth lens on the optical axis satisfy: 5.37 < d7m / T78 < 8.42.

[0012] Furthermore, the following relationships are satisfied between the outer diameter D1s of the object side surface of the first spacer element and the radius of curvature R2 of the image side surface of the first lens: 1.65 < D1s / R2 < 2.74; and between the radius of curvature R1 of the object side surface of the first lens and the central thickness CT1 of the first lens on the optical axis: 6.85 < R1 / CT1 < 9.49.

[0013] Furthermore, the following relationship is satisfied between the axial distance EP12 on the optical axis from the image side surface of the first spacer element to the object side surface of the second spacer element and the air gap T23 on the optical axis between the second lens and the third lens: 4.05 < EP12 / T23 < 7.21.

[0014] Furthermore, the following relationships are satisfied between the inner diameter d2m of the image side surface of the second spacer element and the central thickness CT3 of the third lens on the optical axis: 7.24 < d2m / CT3 < 9.20; and between the effective focal length f3 of the third lens and the inner diameter d2m of the image side surface of the second spacer element: 1.12 < f3 / d2m < 2.13.

[0015] Furthermore, the following relationship is satisfied between the axial distance EP56 on the optical axis from the image side surface of the fifth spacer element to the object side surface of the sixth spacer element and the central thickness CT6 of the sixth lens on the optical axis: 1.47 < EP56 / CT6 < 4.58.

[0016] Furthermore, the following relationship is satisfied among the effective focal length f5 of the fifth lens, the central thickness CT5 of the fifth lens on the optical axis, and the maximum axial thickness CP5 of the fifth spacer element: 1.82 < f5 / (CT5 + CP5) < 5.30.

[0017] Furthermore, the following relationship is satisfied between the axial distance SAG42 on the optical axis from the intersection point of the image side surface of the fourth lens and the optical axis to the vertex of the effective radius of the image side surface of the fourth lens and the maximum axial thickness CP4 of the fourth spacer element: 11.71 < SAG42 / CP4 < 22.19.

[0018] Furthermore, the following relationships are satisfied between the inner diameter d6s of the object side surface of the sixth spacer element and the central thickness CT6 of the sixth lens on the optical axis: 10.93 < d6s / CT6 < 17.99; and between the effective focal length f6 of the sixth lens and the outer diameter D6s of the object side surface of the sixth spacer element: -3.06 < f6 / D6s < -1.95.

[0019] Furthermore, the central thickness CT7 of the seventh lens on the optical axis and the distance EP67 on the optical axis from the image side of the sixth spacer element to the object side of the seventh spacer element satisfy: 0.83 < CT7 / EP67 < 1.71; the effective focal length f7 of the seventh lens and the inner diameter d6m of the image side of the sixth spacer element satisfy: 1.37 < f7 / d6m < 3.08.

[0020] Furthermore, the axial distance SAG12 between the intersection of the image side of the first lens and the optical axis and the effective radius vertex of the image side of the first lens and the maximum axial thickness CP1 of the first spacer element satisfy: 16.65 < SAG12 / CP1 < 23.19.

[0021] Furthermore, the air gap T78 between the seventh lens and the eighth lens on the optical axis and the central thickness CT8 of the eighth lens on the optical axis satisfy: 1.07 < T78 / CT8 < 3.45; the inner diameter d7m of the image side of the seventh spacer element, the air gap T78 between the seventh lens and the eighth lens on the optical axis and the central thickness CT8 of the eighth lens on the optical axis satisfy: 3.58 < d7m / (T78 + CT8) < 4.47.

[0022] Furthermore, the spacer element group further includes an eighth spacer element disposed on the image side of the eighth lens and partially contacting the image side of the eighth lens.

[0023] Furthermore, the spacer element group further includes a fifth auxiliary spacer element disposed on the image side of the fifth spacer element and partially contacting the image side of the fifth spacer element. The maximum axial thickness CP5 of the fifth spacer element, the maximum axial thickness CP5b of the fifth auxiliary spacer element and the central thickness CT6 of the sixth lens on the optical axis satisfy: 0.82 < (CP5 + CP5b) / CT6 < 3.12.

[0024] Applying the technical solution of the present utility model, the optical imaging system of the present application consists of a lens barrel and eight lenses and multiple spacer elements arranged in the lens barrel. By reasonably arranging the optical powers of the eight lenses and the positions of the first spacer element to the seventh spacer element, and setting the center thickness of the fifth lens located in the middle of the optical imaging system to be the largest on the optical axis, it is ensured that the fifth lens can provide better optical performance, thereby enhancing the ability of the fifth lens to correct aberrations such as spherical aberration and coma. Moreover, the fifth lens has a positive optical power, and its thicker central part can help better control the light path, thus optimizing the imaging quality of the optical imaging system. However, in this case, it is easy to make the thickness of the middle lenses uneven, especially the thickness uniformity of the fourth lens and the fifth lens is poor, which increases the stress on the fourth lens and the fifth lens during assembly. The increase in stress easily causes deformation of the fourth lens and the fifth lens, reducing the assembly reliability of the lenses, and进而 seriously affecting the assembly reliability of the optical imaging system. Therefore, by restricting 4.50 < T45 / CP4 < 20.98 and 3.21 < d4m / CT5 < 4.81, it can be ensured that the air gaps of the fourth lens and the fifth lens on the optical axis and the center thicknesses of the fourth lens and the fifth lens are appropriate, which helps to form a stronger structural support among the fourth lens, the fifth lens and the fourth spacer element, and avoids lens displacement or deformation of the fourth lens and the fifth lens caused by vibration or temperature change, thereby improving the assembly stability of the final optical imaging system and the structural stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings forming a part of this application are used to provide a further understanding of the present utility model. The schematic embodiments and descriptions thereof of the present utility model are used to explain the present utility model and do not constitute an improper limitation to the present utility model. In the drawings:

[0026] Figure 1 It shows a dimension marking diagram of the optical imaging system of an optional embodiment of the present utility model;

[0027] Figure 2 It shows a schematic structural diagram of the optical imaging system of Embodiment 1-1 of the present utility model;

[0028] Figure 3 It shows a schematic structural diagram of the optical imaging system of Embodiment 1-2 of the present utility model;

[0029] Figure 4 It shows a schematic structural diagram of the optical imaging system of Embodiment 1-3 of the present utility model;

[0030] Figures 5 to 7 It respectively shows the axial chromatic aberration curve, astigmatism curve and lateral chromatic aberration curve of the optical imaging system of Embodiment 1 of the present utility model;

[0031] Figure 8 A schematic diagram of the optical imaging system of Embodiment 2-1 of this utility model is shown;

[0032] Figure 9 A schematic diagram of the optical imaging system of Embodiment 2-2 of this utility model is shown;

[0033] Figure 10 A schematic diagram of the optical imaging system of embodiments 2-3 of this utility model is shown;

[0034] Figures 11 to 13 The on-axis chromatic aberration curve, astigmatism curve, and magnification chromatic aberration curve of the optical imaging system of Embodiment 2 of this utility model are shown respectively.

[0035] Figure 14 A schematic diagram of the optical imaging system of Embodiment 3-1 of this utility model is shown;

[0036] Figure 15 A schematic diagram of the optical imaging system of Embodiment 3-2 of this utility model is shown;

[0037] Figure 16 A schematic diagram of the optical imaging system of Embodiment 3-3 of this utility model is shown;

[0038] Figures 17 to 19 The on-axis chromatic aberration curve, astigmatism curve, and magnification chromatic aberration curve of the optical imaging system of Embodiment 3 of this utility model are shown respectively.

[0039] Figure 20 and Figure 21 The stress and deformation cloud diagrams of the optical imaging system of Scheme 1 of this utility model are shown respectively when the fifth lens has positive optical power and the center thickness on the optical axis is the largest, T45 / CP4=11.79 and d4m / CT5=3.89;

[0040] Figure 22 and Figure 23 The stress and deformation contour plots of the optical imaging system of Comparative Example 1 are shown respectively when the fifth lens has positive optical power and the center thickness on the optical axis is the largest, T45 / CP4 = 1.27 and d4m / CT5 = 3.14;

[0041] Figure 24 and Figure 25 The stress and deformation contour plots of the optical imaging system of Comparative Example 2 are shown respectively when the fifth lens has positive optical power and the center thickness on the optical axis is the largest, T45 / CP4 = 23.17 and d4m / CT5 = 5.47;

[0042] Figure 26A dimensioned diagram of an optical imaging system according to an alternative embodiment of the present invention is shown.

[0043] The above figures include the following reference numerals:

[0044] P0, Lens tube; E1, First lens; S1, Object-side surface of the first lens; S2, Image-side surface of the first lens; E2, Second lens; S3, Object-side surface of the second lens; S4, Image-side surface of the second lens; E3, Third lens; S5, Object-side surface of the third lens; S6, Image-side surface of the third lens; E4, Fourth lens; S7, Object-side surface of the fourth lens; S8, Image-side surface of the fourth lens; E5, Fifth lens; S9, Object-side surface of the fifth lens; S10, Image-side surface of the fifth lens; E6, Sixth lens; S11, Object-side surface of the sixth lens; S12, Image-side surface of the sixth lens; E7, Seventh lens S13, object-side surface of the seventh lens; S14, image-side surface of the seventh lens; E8, eighth lens; S15, object-side surface of the eighth lens; S16, image-side surface of the eighth lens; P1, first spacer element; P2, second spacer element; P3, third spacer element; P3b, third auxiliary spacer element; P3c, third auxiliary spacer element; P4, fourth spacer element; P5, fifth spacer element; P5b, fifth auxiliary spacer element; P5c, fifth auxiliary spacer element; P6, sixth spacer element; P7, seventh spacer element; P7b, seventh auxiliary spacer element; P8, eighth spacer element. Detailed Implementation

[0045] 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.

[0046] 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.

[0047] In this utility model, 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 used to limit this utility model.

[0048] 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.

[0049] 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.

[0050] 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 shape in the paraxial region can be determined according to the judgment method commonly known in the art, 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, 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, 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. In this application, the left side is the object side, and the right side is the image side.

[0051] To address the problem in existing eight-element optical imaging systems that constrain the optical parameters of the central lens to meet high optical performance requirements, resulting in uneven central lens size and excessive stress after assembly, thus affecting assembly reliability, this invention provides an optical imaging system.

[0052] like Figures 1 to 21 , Figure 26As shown, in an optional embodiment of the present application, an optical imaging system is provided, which includes a lens barrel and a lens group and a spacer element group disposed in the lens barrel. The lens group consists of eight lenses. The eight lenses are, in order from the object side to the image side, a first lens with a positive or negative optical power, a second lens with a negative optical power, a third lens with a positive optical power, a fourth lens with a negative optical power, a fifth lens with a positive optical power, a sixth lens with a negative optical power, a seventh lens with a positive optical power, and an eighth lens with a negative optical power. Among the first lens to the eighth lens, the fifth lens has the largest central thickness on the optical axis of the optical imaging system. The spacer element group includes a first spacer element disposed between the first lens and the second lens and in partial contact with the image side surface of the first lens, a second spacer element disposed between the second lens and the third lens and in partial contact with the image side surface of the second lens, a third spacer element disposed between the third lens and the fourth lens and in partial contact with the image side surface of the third lens, a fourth spacer element disposed between the fourth lens and the fifth lens and in partial contact with the image side surface of the fourth lens, a fifth spacer element disposed between the fifth lens and the sixth lens and in partial contact with the image side surface of the fifth lens, a sixth spacer element disposed between the sixth lens and the seventh lens and in partial contact with the image side surface of the sixth lens, and a seventh spacer element disposed between the seventh lens and the eighth lens and in partial contact with the image side surface of the seventh lens. Among them, the air gap T45 between the fourth lens and the fifth lens on the optical axis and the maximum axial thickness CP4 of the fourth spacer element satisfy: 4.50 < T45 / CP4 < 20.98; the inner diameter d4m of the image side surface of the fourth spacer element and the central thickness CT5 of the fifth lens on the optical axis satisfy: 3.21 < d4m / CT5 < 4.81.

[0053] The optical imaging system of the present application consists of a lens barrel and eight lenses and multiple spacer elements arranged in the lens barrel. By reasonably arranging the optical power of the eight lenses and the positions of the first spacer element to the seventh spacer element, and setting the central thickness of the fifth lens located in the middle of the optical imaging system to be the largest on the optical axis, it is ensured that the fifth lens can provide better optical performance, thereby enhancing the ability of the fifth lens to correct aberrations such as spherical aberration and coma. Moreover, the fifth lens has a positive optical power, and its thicker central part can help better control the light path, thus optimizing the imaging quality of the optical imaging system. However, in this case, it is easy to make the thickness of the middle lenses uneven, especially the thickness uniformity of the fourth lens and the fifth lens is poor, which increases the stress on the fourth lens and the fifth lens during assembly. The increase in stress easily causes deformation of the fourth lens and the fifth lens, reducing the assembly reliability of the lenses, and进而 seriously affecting the assembly reliability of the optical imaging system. Therefore, by constraining 4.50 < T45 / CP4 < 20.98 and 3.21 < d4m / CT5 < 4.81, it can be ensured that the air gaps of the fourth lens and the fifth lens on the optical axis and the central thicknesses of the fourth lens and the fifth lens are appropriate, which helps to form a stronger structural support among the fourth lens, the fifth lens, and the fourth spacer element, avoiding lens displacement or deformation of the fourth lens and the fifth lens caused by vibration or temperature changes, thereby improving the assembly stability of the final optical imaging system and the structural stability.

[0054] In addition, referring to Table 1 below, Figures 20 to 25 as shown, on the premise that the optical imaging system satisfies that the fifth lens has a positive optical power and the central thickness of the fifth lens on the optical axis is the largest, Figure 20 and Figure 21 respectively show the stress nephogram and deformation nephogram of the optical imaging system of Scheme 1 of the present utility model when T45 / CP4 = 11.79 and d4m / CT5 = 3.89; Figure 22 and Figure 23 respectively show the stress nephogram and deformation nephogram of the optical imaging system of Comparative Example 1 when T45 / CP4 = 1.27 and d4m / CT5 = 3.14; Figure 24 and Figure 25 respectively show the stress nephogram and deformation nephogram of the optical imaging system of Comparative Example 2 when T45 / CP4 = 23.17 and d4m / CT / CT5 = 5.47.

[0055] From Figures 20 to 25It can be seen that when the optical imaging system satisfies T45 / CP4 = 11.79 and d4m / CT5 = 3.89, under the same assembly pressure, the stress on the fourth lens and the fifth lens is relatively small, avoiding the risk of deformation or movement of the fourth lens and the fifth lens during assembly, and the overall performance is better. When the optical imaging system satisfies T45 / CP4 = 1.27 and d4m / CT5 = 3.14, the air gap on the optical axis between the fourth lens and the fifth lens is relatively small. During the assembly process, the fourth lens, the fifth lens and the sixth lens are prone to deformation, which may lead to abrasion of the lens surface, and the assembly reliability of the optical imaging system is poor. When the optical imaging system satisfies T45 / CP4 = 23.17 and d4m / CT5 = 5.47, the thickness of the fourth lens is uneven. During the assembly process, stress concentration is likely to occur between the fourth lens and the fifth lens, resulting in poor assembly reliability of the optical imaging system. Thus, it can be seen that when it is satisfied that the fifth lens has a positive optical power and the maximum central thickness on the optical axis, T45 / CP4 is within the range of 4.50 to 20.98, and d4m / CT5 is within the range of 3.21 to 4.81, during the assembly process of the optical imaging system, the assembly stress of the fourth lens and the fifth lens is the smallest, the deformation amount is the smallest, the assembly reliability is the best, and the overall performance is the best. Therefore, by restricting 4.50 < T45 / CP4 < 20.98 and 3.21 < d4m / CT5 < 4.81 in this application, it can ensure that the air gap on the optical axis between the fourth lens and the fifth lens and the central thickness of the fourth lens and the fifth lens are appropriate, which helps to form a stronger structural support between the fourth lens, the fifth lens and the fourth spacer element, avoiding lens displacement or deformation caused by vibration or temperature change of the fourth lens and the fifth lens, thereby improving the assembly stability of the final optical imaging system and the stability of the structure.

[0056] Table 1

[0057]

[0058] <--

[0059] In this embodiment, the spacer element group further includes an eighth spacer element disposed on the image side of the eighth lens and partially contacting the image side surface of the eighth lens, and a fifth auxiliary spacer element disposed on the image side of the fifth spacer element and partially contacting the image side surface of the fifth spacer element. By providing multiple spacer elements, additional fixation and support are provided for the first lens to the eighth lens, which helps to prevent the first lens to the eighth lens from shifting or loosening during assembly or use, thereby ensuring the stability and reliability of the entire optical imaging system.

[0060] In this embodiment, the relationship between the effective focal length f4 of the fourth lens and the radius of curvature R7 of the object side surface of the fourth lens satisfies: -4.85 < f4 / R7 < -1.62; the relationship between the effective focal length f4 of the fourth lens and the inner diameter d3m of the image side surface of the third spacer element satisfies: -4.98 < f4 / d3m < -2.27. By controlling these two conditional expressions, the relationship between the effective focal length of the fourth lens, the radius of curvature of the object side surface of the fourth lens, and the inner diameter of the image side surface of the third spacer element can be restricted, which helps to optimize the effective focal length of the optical imaging system and the position of the imaging surface, so as to control the light path to correct the aberration generated when light passes through the fourth lens, reduce the aberration, and improve the imaging quality of the optical imaging system.

[0061] In this embodiment, the air gap T67 between the sixth lens and the seventh lens on the optical axis, the air gap T78 between the seventh lens and the eighth lens on the optical axis, and the interval distance EP67 on the optical axis from the image side surface of the sixth spacer element to the object side surface of the seventh spacer element satisfy: 0.44 < EP67 / (T78 - T67) < 3.11. By controlling this conditional expression, the difference between the air gap between the seventh lens and the eighth lens on the optical axis and the air gap between the sixth lens and the seventh lens on the optical axis can be restricted within a reasonable range, which helps to ensure that the air gaps between adjacent two lenses among the sixth lens, the seventh lens, and the eighth lens are appropriate, avoiding the situations of too large or too small gaps, thereby enhancing the compactness and stability of the arrangement of the sixth lens, the seventh lens, and the eighth lens in the lens barrel. At the same time, it can also reduce the errors generated during the manufacturing process, achieve high-precision manufacturing and assembly of the optical imaging system, and further improve the overall performance of the optical imaging system.

[0062] In this embodiment, among adjacent two lenses of the first lens to the eighth lens, the air gap between the seventh lens and the eighth lens on the optical axis is the largest. The relationship between the inner diameter d7m of the image side surface of the seventh spacer element and the air gap T78 between the seventh lens and the eighth lens on the optical axis satisfies: 5.37 < d7m / T78 < 8.42. By reasonably controlling that the air gap between the seventh lens and the eighth lens is the largest and this conditional expression, a doublet lens with an air gap can be formed by the seventh lens and the eighth lens, and the air gap between the seventh lens and the eighth lens on the optical axis can be maintained at the largest, so that this doublet lens can minimize the light transmission wavefront error, spot size, and aberration, ensure the imaging quality of the optical imaging system, and further improve the overall performance of the optical imaging system.

[0063] In this embodiment, the following relationships are satisfied between the outer diameter D1s of the object side surface of the first spacer element and the radius of curvature R2 of the image side surface of the first lens: 1.65 < D1s / R2 < 2.74; and between the radius of curvature R1 of the object side surface of the first lens and the central thickness CT1 of the first lens on the optical axis: 6.85 < R1 / CT1 < 9.49. The radius of curvature of the lens and the central thickness on the optical axis jointly determine the effective focal length of the lens. By controlling these two conditional expressions, the radius of curvature of the two side surfaces of the first lens and the central thickness of the first lens on the optical axis can be controlled to adjust the effective focal length of the first lens to meet the application requirements of a specific scenario. At the same time, the outer diameter of the object side surface of the first spacer element can be restricted, which is beneficial to controlling the aperture of the first lens, beneficial to controlling the transmission and focusing of light, and ensuring that the light can maintain the required quality, shape, and trend when passing through the optical imaging system.

[0064] In this embodiment, the following relationship is satisfied between the axial spacing distance EP12 from the image side surface of the first spacer element to the object side surface of the second spacer element and the air spacing T23 between the second lens and the third lens on the optical axis: 4.05 < EP12 / T23 < 7.21. By controlling this conditional expression, the relationship between the axial spacing distance from the image side surface of the first spacer element to the object side surface of the second spacer element and the air spacing between the second lens and the third lens on the optical axis can be controlled, improving the processing feasibility and assembly convenience of the second lens, the third lens, the first spacer element, and the second spacer element. Furthermore, the misalignment amount during the assembly of the second lens and the third lens can be reduced, effectively improving the assembly stability of the optical imaging system, and thus being beneficial to improving the reliability and durability of the optical imaging system.

[0065] In this embodiment, the following relationships are satisfied between the inner diameter d2m of the image side surface of the second spacer element and the central thickness CT3 of the third lens on the optical axis: 7.24 < d2m / CT3 < 9.20; and between the effective focal length f3 of the third lens and the inner diameter d2m of the image side surface of the second spacer element: 1.12 < f3 / d2m < 2.13. By controlling these two conditional expressions, the relationship between the inner diameter of the image side surface of the second spacer element, the central thickness of the third lens on the optical axis, and the effective focal length of the third lens can be controlled, which helps to balance the optical performance and production cost of the optical imaging system, that is, reducing the manufacturing cost and complexity of the optical imaging system while ensuring the imaging quality.

[0066] In this embodiment, the distance EP56 on the optical axis from the image side of the fifth spacer element to the object side of the sixth spacer element and the central thickness CT6 of the sixth lens on the optical axis satisfy: 1.47 < EP56 / CT6 < 4.58. EP56 and CT6 are important parameters affecting the focusing performance and imaging quality of the optical imaging system. EP56 can adjust the path length of light in the optical imaging system, and CT6 can affect the refraction degree of the sixth lens on light. By controlling this conditional expression, key performance indicators such as the effective focal length, spot size, and light quality of the optical imaging system can be regulated, thereby ensuring the imaging quality of the optical imaging system.

[0067] In this embodiment, the effective focal length f5 of the fifth lens, the central thickness CT5 of the fifth lens on the optical axis, and the maximum axial thickness CP5 of the fifth spacer element satisfy: 1.82 < f5 / (CT5 + CP5) < 5.30. CT5 and CP5 can jointly affect the overall optical length and light trend of the optical imaging system. By controlling this conditional expression, the thickness measurement accuracy and positioning accuracy of the fifth lens can be improved, and the risk of reducing the imaging quality of the optical imaging system caused by processing errors or assembly errors of the fifth lens can be avoided.

[0068] In this embodiment, the axial distance SAG42 on the optical axis from the intersection of the image side of the fourth lens and the optical axis to the vertex of the effective radius of the image side of the fourth lens and the maximum axial thickness CP4 of the fourth spacer element satisfy: 11.71 < SAG42 / CP4 < 22.19. SAG42 affects the radius of curvature of the image side of the fourth lens, and CP4 affects the path and length of light. By controlling this conditional expression, the forming stability and assembly stability of the fourth lens can be ensured, and the light collection ability and resolution of the fourth lens can be optimized, thereby improving the light focusing ability and imaging quality of the optical imaging system.

[0069] In this embodiment, the inner diameter d6s of the object side of the sixth spacer element and the central thickness CT6 of the sixth lens on the optical axis satisfy: 10.93 < d6s / CT6 < 17.99; the effective focal length f6 of the sixth lens and the outer diameter D6s of the object side of the sixth spacer element satisfy: -3.06 < f6 / D6s < -1.95. By controlling the ratio of the inner diameter of the object side of the sixth spacer element to the central thickness of the sixth lens on the optical axis, the coma, astigmatism, and other aberrations of the sixth lens can be corrected to a certain extent, thereby improving the imaging quality. At the same time, by restricting the ratio of the effective focal length of the sixth lens to the outer diameter of the object side of the sixth spacer element, the spherical aberration and chromatic aberration generated by the sixth lens can be reduced, and the imaging quality of the optical imaging system can be optimized.

[0070] In this embodiment, the central thickness CT7 of the seventh lens on the optical axis and the axial distance EP67 on the optical axis from the image side of the sixth spacer element to the object side of the seventh spacer element satisfy: 0.83 < CT7 / EP67 < 1.71; the effective focal length f7 of the seventh lens and the inner diameter d6m of the image side of the sixth spacer element satisfy: 1.37 < f7 / d6m < 3.08. By controlling the ratio of the central thickness of the seventh lens on the optical axis to the axial distance on the optical axis from the image side of the sixth spacer element to the object side of the seventh spacer element, it helps to optimize the propagation path of light inside the optical imaging system, reduce unnecessary light loss and the generation of aberrations, and improve the imaging quality of the optical imaging system. At the same time, by restricting the ratio of the effective focal length of the seventh lens to the inner diameter of the image side of the sixth spacer element, the distribution of the effective focal length of the seventh lens in the optical imaging system can be optimized, making the optical imaging system more balanced and efficient.

[0071] In this embodiment, the axial distance SAG12 on the optical axis between the intersection point of the image side of the first lens and the optical axis and the effective radius vertex of the image side of the first lens and the maximum axial thickness CP1 of the first spacer element satisfy: 16.65 < SAG12 / CP1 < 23.19. By controlling this conditional expression, it helps to enhance the stability of the optical imaging system, enabling the optical imaging system to maintain good imaging performance even when the temperature or humidity changes, and improving the reliability of the optical imaging system.

[0072] In this embodiment, the air gap T78 between the seventh lens and the eighth lens on the optical axis and the central thickness CT8 of the eighth lens on the optical axis satisfy: 1.07 < T78 / CT8 < 3.45; the inner diameter d7m of the image side of the seventh spacer element, the air gap T78 between the seventh lens and the eighth lens on the optical axis and the central thickness CT8 of the eighth lens on the optical axis satisfy: 3.58 < d7m / (T78 + CT8) < 4.47. By controlling these two conditional expressions, the propagation path and deflection degree of light when passing through the seventh lens and the eighth lens can be adjusted, improving the imaging quality of the optical imaging system. At the same time, it is also beneficial to the molding stability of the injection molding process of the seventh lens and the eighth lens, thereby improving the processability of the optical imaging system.

[0073] In this embodiment, the maximum axial thickness CP5 of the fifth spacer element, the maximum axial thickness CP5b of the fifth auxiliary spacer element, and the center thickness CT6 of the sixth lens on the optical axis satisfy the following condition: 0.82 < (CP5 + CP5b) / CT6 < 3.12. The optical imaging system introduces a fifth auxiliary spacer element. By controlling this condition, the propagation path of light between the fifth and sixth lenses can be appropriately adjusted, reducing unnecessary light loss and avoiding aberrations caused by improper air spacing or lens thickness mismatch. This helps improve the imaging quality of the optical imaging system, making the image clearer and sharper.

[0074] In this embodiment, the object-side surface of the first lens is convex, and the image-side surface is concave; the object-side surface of the second lens is convex, and the image-side surface is concave; the object-side surface of the third lens is convex; the object-side surface of the fourth lens is convex, and the image-side surface is concave; the object-side surface of the fifth lens is convex, and the image-side surface is convex; the object-side surface of the sixth lens is convex, and the image-side surface is concave; and the object-side surface of the seventh lens is convex. By rationally planning the surface shape of each lens, it is beneficial to control the light path, eliminate aberrations, and ensure image quality.

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

[0076] In addition, in another optional embodiment of the present application, an optical imaging system is further provided, which includes a lens barrel and a lens group and a spacer element group disposed in the lens barrel. The lens group consists of eight lenses. The eight lenses are, in order from the object side to the image side, a first lens with a positive or negative optical power, a second lens with a negative optical power, a third lens with a positive optical power, a fourth lens with a negative optical power, a fifth lens with a positive optical power, a sixth lens with a negative optical power, a seventh lens with a positive optical power, and an eighth lens with a negative optical power. Among the first lens to the eighth lens, the fifth lens has the largest central thickness on the optical axis of the optical imaging system. The spacer element group includes a first spacer element disposed between the first lens and the second lens and in partial contact with the image side surface of the first lens, a second spacer element disposed between the second lens and the third lens and in partial contact with the image side surface of the second lens, a third spacer element disposed between the third lens and the fourth lens and in partial contact with the image side surface of the third lens, a fourth spacer element disposed between the fourth lens and the fifth lens and in partial contact with the image side surface of the fourth lens, a fifth spacer element disposed between the fifth lens and the sixth lens and in partial contact with the image side surface of the fifth lens, a sixth spacer element disposed between the sixth lens and the seventh lens and in partial contact with the image side surface of the sixth lens, and a seventh spacer element disposed between the seventh lens and the eighth lens and in partial contact with the image side surface of the seventh lens. Among them, the inner diameter d4m of the image side surface of the fourth spacer element and the central thickness CT5 of the fifth lens on the optical axis satisfy: 3.21 < d4m / CT5 < 4.8; the axial distance SAG42 between the intersection of the image side surface of the fourth lens and the optical axis and the vertex of the effective radius of the image side surface of the fourth lens and the maximum axial thickness CP4 of the fourth spacer element satisfy: 11.71 < SAG42 / CP4 < 22.19.

[0077] The optical imaging system of the present application consists of a lens barrel, eight lenses and multiple spacer elements arranged in the lens barrel. By reasonably arranging the optical powers of the eight lenses and the positions of the first spacer element to the seventh spacer element, and setting the central thickness of the fifth lens located in the middle of the optical imaging system to be the largest on the optical axis, it is ensured that the fifth lens can provide better optical performance, thereby enhancing the ability of the fifth lens to correct aberrations such as spherical aberration and coma. Moreover, the fifth lens has a positive optical power, and its thicker central part can help to better control the light path, thereby optimizing the imaging quality of the optical imaging system. However, in this case, it is easy to make the thickness of the middle lens uneven, especially the thickness uniformity of the fourth lens and the fifth lens is poor, which increases the stress on the fourth lens and the fifth lens during assembly. The increase in stress easily causes deformation of the fourth lens and the fifth lens, reducing the assembly reliability of the lenses, and thus seriously affecting the assembly reliability of the optical imaging system. Therefore, by restricting 3.21 < d4m / CT5 < 4.81 and 11.71 < SAG42 / CP4 < 22.19, it helps to form a stronger structural support between the fourth lens, the fifth lens and the fourth spacer element, which can ensure the forming stability and assembly stability of the fourth lens, avoid lens displacement or deformation caused by vibration or temperature change of the fourth lens and the fifth lens, thereby improving the assembly stability and structural stability of the final optical imaging system; it can also optimize the light collection ability and resolution of the fourth lens, and further improve the light focusing ability and imaging quality of the optical imaging system.

[0078] Of course, other parametric formulas in the above embodiments may also be included in this embodiment, which will not be elaborated here one by one.

[0079] In addition, in another optional embodiment of the present application, an optical imaging system is further provided, which includes a lens barrel and a lens group and a spacer element group disposed in the lens barrel. The lens group consists of eight lenses. The eight lenses are, in order from the object side to the image side, a first lens with a positive or negative optical power, a second lens with a negative optical power, a third lens with a positive optical power, a fourth lens with a negative optical power, a fifth lens with a positive optical power, a sixth lens with a negative optical power, a seventh lens with a positive optical power, and an eighth lens with a negative optical power. Among the first lens to the eighth lens, the fifth lens has the largest central thickness on the optical axis of the optical imaging system. The spacer element group includes a first spacer element disposed between the first lens and the second lens and partially contacting the image side surface of the first lens, a second spacer element disposed between the second lens and the third lens and partially contacting the image side surface of the second lens, a third spacer element disposed between the third lens and the fourth lens and partially contacting the image side surface of the third lens, a fourth spacer element disposed between the fourth lens and the fifth lens and partially contacting the image side surface of the fourth lens, a fifth spacer element disposed between the fifth lens and the sixth lens and partially contacting the image side surface of the fifth lens, a sixth spacer element disposed between the sixth lens and the seventh lens and partially contacting the image side surface of the sixth lens, and a seventh spacer element disposed between the seventh lens and the eighth lens and partially contacting the image side surface of the seventh lens. Among them, the effective focal length f4 of the fourth lens and the central thickness CT5 of the fifth lens on the optical axis satisfy: 4.90 < f4 / CT5 < 6.30; the inner diameter d4m of the image side surface of the fourth spacer element, the maximum axial thickness CP4 of the fourth spacer element, and the air gap T45 between the fourth lens and the fifth lens on the optical axis satisfy: 10.20 < d4m / (CP4 + T45) < 38.26.

[0080] The optical imaging system of the present application consists of a lens barrel, eight lenses and multiple spacer elements arranged in the lens barrel. By reasonably arranging the optical powers of the eight lenses and the positions of the first spacer element to the seventh spacer element, and setting the central thickness of the fifth lens located in the middle of the optical imaging system to be the largest on the optical axis, it is ensured that the fifth lens can provide better optical performance, thereby enhancing the ability of the fifth lens to correct aberrations such as spherical aberration and coma. Moreover, the fifth lens has a positive optical power, and its thicker central part can help to better control the light path, thus optimizing the imaging quality of the optical imaging system. However, in this case, it is easy to make the thickness of the middle lenses uneven, especially the thickness uniformity of the fourth lens and the fifth lens is poor, which increases the stress on the fourth lens and the fifth lens during assembly. The increase in stress easily causes deformation of the fourth lens and the fifth lens, reducing the assembly reliability of the lenses, and further seriously affecting the assembly reliability of the optical imaging system. Therefore, in the present application, by restricting 4.90 < f4 / CT5 < 6.30 and 10.20 < d4m / (CP4 + T45) < 38.26, the ratio of the effective focal length of the fourth lens to the central thickness of the fifth lens on the optical axis and the relationship between the inner diameter of the image side of the fourth spacer element, the maximum axial thickness of the fourth spacer element and the air gap between the fourth lens and the fifth lens on the optical axis are controlled. On the basis of ensuring the optical performance of the fourth lens and the fifth lens, it is ensured that the distance between the fourth lens and the fifth lens is appropriate, and at the same time, the rationality of the shapes and sizes of the fourth lens and the fifth lens can be restricted, which is beneficial to reducing the phenomenon of stress concentration between the fourth lens and the fifth lens after assembly, avoiding the risk of deformation of the fourth lens and the fifth lens, and thus improving the assembly stability of the final optical imaging system and the structural stability.

[0081] Of course, other parametric expressions in the above embodiments may also be included in this embodiment, which will not be elaborated here one by one.

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

[0083] In the optical imaging system of the present application, multiple lenses can be used, such as the eight lenses mentioned above. In the present application, at least one of the lens surfaces of each lens is an aspherical surface. The characteristics of an aspherical lens are that the curvature changes continuously from the center of the lens to the periphery of the lens. Different from a spherical lens with a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has better curvature radius characteristics and has the advantages of improving distortion aberration and astigmatism aberration. After using an aspherical lens, it is possible to eliminate the aberrations that occur during imaging as much as possible, thereby improving the imaging quality.

[0084] However, those skilled in the art will understand that the number of lenses constituting the optical imaging system can be changed without departing from the technical solutions claimed in this application to obtain the various results and advantages described in this specification. For example, although an embodiment is described using eight lenses as an example, the optical imaging system is not limited to including eight lenses. If necessary, the optical imaging system may also include other numbers of lenses.

[0085] Figure 1 and Figure 26 A schematic diagram showing the dimensions of an optical imaging system according to this application is provided. Figure 1 The winning bid specifies parameters such as D1s, d2m, d3m, d4m, d6s, d6m, D6s, d7m, CP1, EP12, CP4, CP5, EP56, and EP67. Figure 26 SAG12, SAG42, and CP5b are indicated to clearly and intuitively illustrate the meaning of this parameter. To facilitate the description of the optical imaging system and the specific lens profiles, these parameters will not be shown in the accompanying drawings when describing specific embodiments.

[0086] 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.

[0087] It should be noted that in the following Embodiment 1, there are three examples: Embodiment 1-1, Embodiment 1-2, and Embodiment 1-3; in Embodiment 2, there are three examples: Embodiment 2-1, Embodiment 2-2, and Embodiment 2-3; and in Embodiment 3, there are three examples: Embodiment 3-1, Embodiment 3-2, and Embodiment 3-3. In the three examples within the same embodiment, the parameters such as the radius of curvature, center thickness, and inter-lens spacing and higher-order coefficients of the optical imaging system from the first to the eighth lens are the same. However, the parameters such as the thickness, inner diameter, and outer diameter of the lens barrel, the first spacer element, and the eighth spacer element are different. In other words, the main structure used for imaging is the same, but the auxiliary structures used for imaging are different.

[0088] It should be noted that any one of the examples in Embodiments 1 to 3 described below is applicable to all implementations of this application.

[0089] Example 1

[0090] like Figures 2 to 7 As shown, the optical imaging system of Embodiment 1 is described. Figure 2 A schematic diagram of the optical imaging system of Embodiment 1-1 is shown. Figure 3 A schematic diagram of the optical imaging system of Embodiments 1-2 is shown. Figure 4 A schematic diagram of the optical imaging system of Examples 1-3 is shown.

[0091] like Figures 2 to 4 As shown, the optical imaging system includes a lens barrel P0 and a first lens E1, a first spacer P1, a second lens E2, a second spacer P2, a third lens E3, a third spacer P3, a fourth lens E4, a fourth spacer P4, a fifth lens E5, a fifth spacer P5, a sixth lens E6, a sixth spacer P6, a seventh lens E7, a seventh spacer P7, an eighth lens E8, and an eighth spacer P8 arranged sequentially along the optical axis from the object side to the image side in the lens barrel P0.

[0092] like Figure 2 The diagram shows a schematic of the optical imaging system of Embodiment 1-1. In this example, the object-side and image-side of the first spacer element P1 are in partial contact with the image-side S2 of the first lens and the object-side S3 of the second lens, respectively. The object-side and image-side of the second spacer element P2 are in partial contact with the image-side S4 of the second lens and the object-side S5 of the third lens, respectively. The object-side and image-side of the third spacer element P3 are in partial contact with the image-side S6 of the third lens and the object-side S7 of the fourth lens, respectively. The object-side and image-side of the fourth spacer element P4 are in partial contact with the image-side S8 of the fourth lens and the object-side S9 of the fifth lens, respectively. The object-side and image-side of the fifth spacer element P5 are in partial contact with the image-side S10 of the fifth lens and the object-side S11 of the sixth lens, respectively. The object-side and image-side of the sixth spacer element P6 are in partial contact with the image-side S12 of the sixth lens and the object-side S13 of the seventh lens, respectively. The object-side and image-side of the seventh spacer element P7 are in partial contact with the image-side S14 of the seventh lens and the object-side S15 of the eighth lens, respectively. The object side of the eighth spacer element P8 is in contact with the image side S16 of the eighth lens.

[0093] like Figure 3 The diagram shown is a schematic representation of the optical imaging system of Embodiment 1-2. In this example, the contact method between the spacer elements is the same as in Embodiment 1-1, and can be found in the relevant description in Embodiment 1-1, which will not be repeated here.

[0094] like Figure 4The diagram shows a schematic of the optical imaging system according to Embodiments 1-3. In this example, the image side of the fifth spacer element P5 is further provided with a fifth auxiliary spacer element P5b and a fifth secondary auxiliary spacer element P5c. At this time, the image side of the fifth spacer element P5 is in contact with the object side of the fifth auxiliary spacer element P5b, the image side of the fifth auxiliary spacer element P5b is in contact with the object side of the fifth secondary auxiliary spacer element P5c, and the image side of the fifth secondary auxiliary spacer element P5c is in contact with the object side S11 of the sixth lens. Apart from this, the contact and abutment methods of the remaining spacer elements are the same as in Embodiments 1-1, and can be referred to the relevant descriptions in Embodiments 1-1, which will not be repeated here.

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

[0096] Table 2

[0097] Parameters / Examples 1-1 1-2 1-3 D1s 4.914 5.900 5.910 d2m 4.098 4.054 4.154 d3m 4.059 4.015 4.115 d4m 4.637 4.593 4.493 d6s 5.927 5.883 6.027 d6m 5.927 5.883 5.983 D6s 8.261 8.161 8.206 d7m 6.536 6.492 6.792 CP1 0.020 0.021 0.022 EP12 0.335 0.345 0.357 CP4 0.020 0.021 0.022 CP5 1.076 1.076 0.022 EP56 0.532 0.632 1.586 EP67 0.499 0.509 0.511 CP5b 1.054

[0098] In Embodiment 1, the object-side surface S1 of the first lens is convex, and the image-side surface S2 of the first lens is concave. The object-side surface S3 of the second lens is convex, and the image-side surface S4 of the second lens is concave. The object-side surface S5 of the third lens is convex, and the image-side surface S6 of the third lens is convex. The object-side surface S7 of the fourth lens is convex, and the image-side surface S8 of the fourth lens is concave. The object-side surface S9 of the fifth lens is convex, and the image-side surface S10 of the fifth lens is convex. The object-side surface S11 of the sixth lens is convex, and the image-side surface S12 of the sixth lens is concave. The object-side surface S13 of the seventh lens is convex, and the image-side surface S14 of the seventh lens is convex. The object-side surface S15 of the eighth lens is concave, and the image-side surface S16 of the eighth lens is convex.

[0099] In Embodiment 1, the effective focal length f of the optical imaging system is 5.97 mm, the effective focal length f1 of the first lens is 52.46 mm, the effective focal length f2 of the second lens is -11.39 mm, the effective focal length f3 of the third lens is 4.86 mm, the effective focal length f4 of the fourth lens is -9.60 mm, the effective focal length f5 of the fifth lens is 5.24 mm, the effective focal length f6 of the sixth lens is -16.51 mm, the effective focal length f7 of the seventh lens is 8.46 mm, the effective focal length f8 of the eighth lens is -4.83 mm, the axial distance SAG12 between the intersection of the image-side surface of the first lens and the optical axis and the vertex of the effective radius of the image-side surface of the first lens is 0.46 mm, and the axial distance SAG42 between the intersection of the image-side surface of the fourth lens and the optical axis and the vertex of the effective radius of the image-side surface of the fourth lens is 0.44 mm.

[0100] Table 3 shows the basic structural parameters of the optical imaging system in Embodiment 1, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0101] Table 3

[0102]

[0103] In Embodiment 1, the object-side surface and image-side surface of the first lens E1 to the eighth lens E8 are both aspherical. The surface shape of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0104]

[0105] 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, i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 3 above; k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 4 below gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16 and A18 that can be used for each aspherical mirror S1-S16 in Example 1.

[0106] Table 4

[0107]

[0108]

[0109] Figure 5 The on-axis chromatic aberration curve of the optical imaging system of Embodiment 1 is shown, which represents the deflection of the focal point of light of different wavelengths after passing through the optical imaging system. Figure 6 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 7 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.

[0110] according to Figures 5 to 7 As can be seen, the optical imaging system given in Example 1 can achieve good imaging quality.

[0111] Example 2

[0112] like Figures 8 to 13 As shown, the optical imaging system of Embodiment 2 is described. Figure 8 A schematic diagram of the optical imaging system of Embodiment 2-1 is shown. Figure 9 A schematic diagram of the optical imaging system of Embodiment 2-2 is shown. Figure 10 A schematic diagram of the optical imaging system of Embodiments 2-3 is shown.

[0113] like Figures 8 to 10 As shown, the optical imaging system includes a lens barrel P0 and a first lens E1, a first spacer P1, a second lens E2, a second spacer P2, a third lens E3, a third spacer P3, a fourth lens E4, a fourth spacer P4, a fifth lens E5, a fifth spacer P5, a sixth lens E6, a sixth spacer P6, a seventh lens E7, a seventh spacer P7, an eighth lens E8, and an eighth spacer P8 arranged sequentially along the optical axis from the object side to the image side in the lens barrel P0.

[0114] like Figure 8 The diagram shows a schematic of the optical imaging system of Embodiment 2-1. In this example, the object-side and image-side of the first spacer element P1 are in partial contact with the image-side S2 of the first lens and the object-side S3 of the second lens, respectively. The object-side and image-side of the second spacer element P2 are in partial contact with the image-side S4 of the second lens and the object-side S5 of the third lens, respectively. The object-side and image-side of the third spacer element P3 are in partial contact with the image-side S6 of the third lens and the object-side S7 of the fourth lens, respectively. The object-side and image-side of the fourth spacer element P4 are in partial contact with the image-side S8 of the fourth lens and the object-side S9 of the fifth lens, respectively. The object-side and image-side of the fifth spacer element P5 are in partial contact with the image-side S10 of the fifth lens and the object-side S11 of the sixth lens, respectively. The object-side and image-side of the sixth spacer element P6 are in partial contact with the image-side S12 of the sixth lens and the object-side S13 of the seventh lens, respectively. The object-side and image-side of the seventh spacer element P7 are in partial contact with the image-side S14 of the seventh lens and the object-side S15 of the eighth lens, respectively. The object side of the eighth spacer element P8 is in contact with the image side S16 of the eighth lens.

[0115] like Figure 9 The diagram shows a schematic of the optical imaging system of Embodiment 2-2. In this example, the image side of the third spacer element P3 is further provided with a third auxiliary spacer element P3b and a third auxiliary spacer element P3c, and the image side of the fifth spacer element P5 is further provided with a fifth auxiliary spacer element P5b. The image side of the third spacer element P3 is in contact with the object side of the third auxiliary spacer element P3b, the image side of the third auxiliary spacer element P3b is in contact with the object side of the third auxiliary spacer element P3c, and the image side of the third auxiliary spacer element P3c is in contact with the object side S7 of the fourth lens. The image side of the fifth spacer element P5 is in contact with the object side of the fifth auxiliary spacer element P5b, and the image side of the fifth auxiliary spacer element P5b is in contact with the object side S11 of the sixth lens. Apart from this, the contact and abutment methods of the remaining spacer elements are the same as in Embodiment 2-1, and can be referred to the relevant description in Embodiment 2-1, which will not be repeated here.

[0116] like Figure 10 The diagram shows a schematic of the optical imaging system of Embodiment 2-3. In this example, a fifth auxiliary spacer P5c is also provided on the image side of the fifth auxiliary spacer P5b, and a seventh auxiliary spacer P7b is also provided on the image side of the seventh spacer P7. At this time, the image side of the fifth auxiliary spacer P5b is in partial contact with the object side of the fifth auxiliary spacer P5c, and the image side of the fifth auxiliary spacer P5c is in partial contact with the object side S11 of the sixth lens. The image side of the seventh spacer P7 is in partial contact with the object side of the seventh auxiliary spacer P7b, and the image side of the seventh auxiliary spacer P7b is in partial contact with the object side S15 of the eighth lens. Apart from this, the contact and abutment methods of the remaining spacers are the same as in Embodiment 2-2, and can be referred to the relevant description in Embodiment 2-2, which will not be repeated here.

[0117] In summary, the structural parameters of the optical imaging system of Embodiment 2 under Embodiments 2-1, 2-2, and 2-3 are shown in Table 5 (unit: mm).

[0118] Table 5

[0119] Parameters / Examples 2-1 2-2 2-3 D1s 4.723 4.763 4.743 d2m 4.100 4.180 4.080 d3m 4.257 3.878 3.834 d4m 4.391 4.491 4.591 d6s 6.278 6.078 6.178 d6m 6.234 6.034 6.134 D6s 7.797 7.697 7.897 d7m 7.247 7.147 6.582 CP1 0.020 0.021 0.022 EP12 0.297 0.307 0.287 CP4 0.021 0.022 0.020 CP5 0.813 0.021 0.022 EP56 0.780 1.571 1.561 EP67 0.374 0.373 0.363 CP5b 0.791 0.769

[0120] In Embodiment 2, the object-side surface S1 of the first lens is convex, and the image-side surface S2 of the first lens is concave. The object-side surface S3 of the second lens is convex, and the image-side surface S4 of the second lens is concave. The object-side surface S5 of the third lens is convex, and the image-side surface S6 of the third lens is concave. The object-side surface S7 of the fourth lens is convex, and the image-side surface S8 of the fourth lens is concave. The object-side surface S9 of the fifth lens is convex, and the image-side surface S10 of the fifth lens is convex. The object-side surface S11 of the sixth lens is convex, and the image-side surface S12 of the sixth lens is concave. The object-side surface S13 of the seventh lens is convex, and the image-side surface S14 of the seventh lens is concave. The object-side surface S15 of the eighth lens is concave, and the image-side surface S16 of the eighth lens is concave.

[0121] In Embodiment 2, the effective focal length f of the optical imaging system is 4.95 mm, the effective focal length f1 of the first lens is -34.43 mm, the effective focal length f2 of the second lens is -139.11 mm, the effective focal length f3 of the third lens is 8.48 mm, the effective focal length f4 of the fourth lens is -18.91 mm, the effective focal length f5 of the fifth lens is 4.04 mm, the effective focal length f6 of the sixth lens is -16.03 mm, the effective focal length f7 of the seventh lens is 18.26 mm, the effective focal length f8 of the eighth lens is -5.51 mm, the on-axis distance SAG12 between the intersection of the image-side surface of the first lens and the optical axis and the vertex of the effective radius of the image-side surface of the first lens is 0.37 mm, and the on-axis distance SAG42 between the intersection of the image-side surface of the fourth lens and the optical axis and the vertex of the effective radius of the image-side surface of the fourth lens is 0.26 mm.

[0122] Table 6 shows the basic structural parameters of the optical imaging system in Embodiment 2, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0123] Table 6

[0124]

[0125] Table 7 below shows the higher-order coefficients A4, A6, A8, A10, A12, A14, A16 and A18 that can be used for each aspherical lens S1-S16 in Example 2. The surface shape of each aspherical lens is defined according to formula (1) in Example 1.

[0126] Table 7

[0127]

[0128]

[0129] Figure 11 The on-axis chromatic aberration curve of the optical imaging system of Embodiment 2 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the optical imaging system. Figure 12 The astigmatism curves of the optical imaging system of Embodiment 2 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 13 The magnification chromatic aberration curve of the optical imaging system of Embodiment 2 is shown, which represents the deviation of light at different image heights on the imaging surface after passing through the optical imaging system.

[0130] according to Figures 11 to 13 It can be seen that the optical imaging system given in Example 2 can achieve good imaging quality.

[0131] Example 3

[0132] like Figures 14 to 19As shown, the optical imaging system of Embodiment 3 is described. Figure 14 A schematic diagram of the optical imaging system of Embodiment 3-1 is shown. Figure 15 A schematic diagram of the optical imaging system of Embodiment 3-2 is shown. Figure 16 A schematic diagram of the optical imaging system of Embodiment 3-3 is shown.

[0133] like Figures 14 to 16 As shown, the optical imaging system includes a lens barrel P0 and a first lens E1, a first spacer P1, a second lens E2, a second spacer P2, a third lens E3, a third spacer P3, a fourth lens E4, a fourth spacer P4, a fifth lens E5, a fifth spacer P5, a fifth auxiliary spacer P5b, a sixth lens E6, a sixth spacer P6, a seventh lens E7, a seventh spacer P7, an eighth lens E8, and an eighth spacer P8 arranged sequentially along the optical axis from the object side to the image side in the lens barrel P0.

[0134] like Figure 14 The diagram shows a schematic of the optical imaging system of Embodiment 3-1. In this example, the object-side and image-side of the first spacer element P1 are in partial contact with the image-side S2 of the first lens and the object-side S3 of the second lens, respectively. The object-side and image-side of the second spacer element P2 are in partial contact with the image-side S4 of the second lens and the object-side S5 of the third lens, respectively. The object-side and image-side of the third spacer element P3 are in partial contact with the image-side S6 of the third lens and the object-side S7 of the fourth lens, respectively. The object-side and image-side of the fourth spacer element P4 are in partial contact with the image-side S8 of the fourth lens and the object-side S9 of the fifth lens, respectively. The object-side and image-side of the fifth spacer element P5 are in partial contact with the image-side S10 of the fifth lens and the object-side of the fifth auxiliary spacer element P5b, respectively. The image-side of the fifth auxiliary spacer element P5b is in partial contact with the object-side S11 of the sixth lens. The object-side and image-side of the sixth spacer element P6 are in partial contact with the image-side S12 of the sixth lens and the object-side S13 of the seventh lens, respectively. The object-side and image-side surfaces of the seventh spacer element P7 are in partial contact with the image-side surface S14 of the seventh lens and the object-side surface S15 of the eighth lens, respectively. The object-side surface of the eighth spacer element P8 is in partial contact with the image-side surface S16 of the eighth lens.

[0135] like Figure 15 The diagram shown is a schematic representation of the optical imaging system of Embodiment 3-2. In this example, the contact method between the spacer elements is the same as in Embodiment 3-1, and can be found in the relevant description in Embodiment 3-1, which will not be repeated here.

[0136] like Figure 16The diagram shown is a schematic representation of the optical imaging system in Embodiment 3-3. In this example, a fifth auxiliary spacer element P5c is also provided on the image side of the fifth auxiliary spacer element P5b. At this time, the image side of the fifth auxiliary spacer element P5b partially contacts the object side of the fifth auxiliary spacer element P5c, and the image side of the fifth auxiliary spacer element P5c partially contacts the object side S11 of the sixth lens. Apart from this, the contact and abutment methods of the remaining spacer elements are the same as in Embodiment 3-1, and can be referred to the relevant description in Embodiment 3-1, which will not be repeated here.

[0137] In summary, the structural parameters of the optical imaging system of Embodiment 3 under Embodiments 3-1, 3-2, and 3-3 are shown in Table 8 (unit: mm).

[0138] Table 8

[0139] Parameters / Examples 3-1 3-2 3-3 D1s 5.585 6.610 6.710 d2m 4.159 3.747 3.847 d3m 3.839 3.739 3.939 d4m 4.626 4.526 4.726 d6s 6.588 6.688 6.788 d6m 6.588 6.688 6.788 D6s 9.600 9.700 9.800 d7m 6.338 6.438 6.538 CP1 0.020 0.021 0.022 EP12 0.504 0.428 0.438 CP4 0.020 0.021 0.022 CP5 0.020 0.021 0.022 EP56 1.183 1.173 1.163 EP67 0.805 0.795 0.785 CP5b 0.516 0.516 0.505

[0140] In Embodiment 3, the object-side surface S1 of the first lens is convex, and the image-side surface S2 of the first lens is concave. The object-side surface S3 of the second lens is convex, and the image-side surface S4 of the second lens is concave. The object-side surface S5 of the third lens is convex, and the image-side surface S6 of the third lens is convex. The object-side surface S7 of the fourth lens is convex, and the image-side surface S8 of the fourth lens is concave. The object-side surface S9 of the fifth lens is convex, and the image-side surface S10 of the fifth lens is convex. The object-side surface S11 of the sixth lens is convex, and the image-side surface S12 of the sixth lens is concave. The object-side surface S13 of the seventh lens is convex, and the image-side surface S14 of the seventh lens is convex. The object-side surface S15 of the eighth lens is convex, and the image-side surface S16 of the eighth lens is concave.

[0141] In Embodiment 3, the effective focal length f of the optical imaging system is 5.44 mm, the effective focal length f1 of the first lens is -102.96 mm, the effective focal length f2 of the second lens is -42.97 mm, the effective focal length f3 of the third lens is 6.31 mm, the effective focal length f4 of the fourth lens is -9.13 mm, the effective focal length f5 of the fifth lens is 5.34 mm, the effective focal length f6 of the sixth lens is -28.91 mm, the effective focal length f7 of the seventh lens is 9.68 mm, the effective focal length f8 of the eighth lens is -5.53 mm, the on-axis distance SAG12 between the intersection of the image-side surface of the first lens and the optical axis and the vertex of the effective radius of the image-side surface of the first lens is 0.42 mm, and the on-axis distance SAG42 between the intersection of the image-side surface of the fourth lens and the optical axis and the vertex of the effective radius of the image-side surface of the fourth lens is 0.36 mm.

[0142] Table 9 shows the basic structural parameters of the optical imaging system in Embodiment 3, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0143] Table 9

[0144]

[0145] Table 10 below gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16 and A18 that can be used for each aspherical lens S1-S16 in Example 3. The surface shape of each aspherical lens is defined according to formula (1) in Example 1.

[0146] Table 10

[0147]

[0148]

[0149] Figure 17 The on-axis chromatic aberration curve of the optical imaging system of Embodiment 3 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the optical imaging system. Figure 18 The astigmatism curves of the optical imaging system of Embodiment 3 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 19 The magnification chromatic aberration curve of the optical imaging system of Embodiment 3 is shown, which represents the deviation of light at different image heights on the imaging surface after passing through the optical imaging system.

[0150] according to Figures 17 to 19 As can be seen, the optical imaging system given in Example 3 can achieve good imaging quality.

[0151] In summary, Examples 1 to 3 respectively satisfy the relationships shown in Table 11.

[0152] Table 11

[0153] Conditional / Example 1-1 1-2 1-3 2-1 2-2 2-3 3-1 3-2 3-3 T45 / CP4 20.94 19.94 19.03 4.76 4.55 5.00 12.39 11.80 11.26 d4m / CT5 4.76 4.71 4.61 3.25 3.33 3.40 3.98 3.89 4.06 SAG42 / CP4 22.00 20.95 20.00 12.38 11.82 13.00 18.00 17.14 16.36 f4 / R7 -2.17 -2.17 -2.17 -4.81 -4.81 -4.81 -1.66 -1.66 -1.66 f4 / d3m -2.37 -2.39 -2.33 -4.44 -4.88 -4.93 -2.38 -2.44 -2.32 EP67 / (T78-T67) 2.44 2.48 2.49 0.51 0.51 0.49 3.06 3.02 2.98 d7m / T78 5.49 5.45 5.70 5.97 5.89 5.42 8.12 8.25 8.37 D1s / R2 1.75 2.11 2.11 1.70 1.72 1.71 2.24 2.65 2.69 R1 / CT1 7.27 7.27 7.27 9.44 9.44 9.44 6.90 6.90 6.90 SAG12 / CP1 23.00 21.90 20.91 18.50 17.62 16.82 21.00 20.00 19.09 EP12 / T23 6.70 6.90 7.14 4.24 4.39 4.10 7.17 6.09 6.23 d2m / CT3 7.60 7.52 7.70 7.33 7.47 7.29 9.15 8.24 8.46 f3 / d2m 1.19 1.20 1.17 2.07 2.03 2.08 1.52 1.68 1.64 (CP5+CP5b) / CT6 3.07 2.32 2.26 0.89 0.90 0.88 EP56 / CT6 1.52 1.81 4.53 2.23 4.49 4.46 1.97 1.96 1.94 f5 / (CT5+CP5) 2.56 2.56 5.26 1.87 2.95 2.95 4.51 4.51 4.50 d6s / CT6 16.93 16.81 17.22 17.94 17.37 17.65 10.98 11.15 11.31 f6 / D6s -2.00 -2.02 -2.01 -2.06 -2.08 -2.03 -3.01 -2.98 -2.95 CT7 / EP67 1.43 1.40 1.40 1.61 1.62 1.66 0.88 0.89 0.90 f7 / d6m 1.43 1.44 1.41 2.93 3.03 2.98 1.47 1.45 1.43 T78 / CT8 3.40 3.40 3.40 2.02 2.02 2.02 1.12 1.12 1.12 d7m / (T78+CT8) 4.24 4.21 4.41 3.99 3.94 3.63 4.28 4.35 4.42 f4 / CT5 4.99 4.99 4.99 6.29 6.29 6.29 5.42 5.42 5.42 d4m / (CP4+T45) 10.57 10.45 10.2 36.29 36.81 38.26 17.28 16.84 17.52

[0154] Table 12 shows the effective focal length, effective focal length of each lens, and SAG parameters of the optical imaging systems of Examples 1 to 3.

[0155] Table 12

[0156] Parameters / Examples one two three f(mm) 5.97 4.95 5.44 f1(mm) 52.46 -34.43 -102.96 f2 (mm) -11.39 -139.11 -42.97 f3 (mm) 4.86 8.48 6.31 f4 (mm) -9.60 -18.91 -9.13 f5 (mm) 5.24 4.04 5.34 f6 (mm) -16.51 -16.03 -28.91 f7 (mm) 8.46 18.26 9.68 f8(mm) -4.83 -5.51 -5.53 SAG12 (mm) 0.46 0.37 0.42 SAG42 (mm) 0.44 0.26 0.36

[0157] 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.

[0158] Obviously, the embodiments described above are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0159] 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.

[0160] 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.

[0161] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. An optical imaging system, characterized in that, It includes a lens barrel, a lens group and a spacer element group disposed in the lens barrel. The lens group consists of eight lenses. The eight lenses are, in order from the object side to the image side, a first lens with a positive or negative optical power, a second lens with a negative optical power, a third lens with a positive optical power, a fourth lens with a negative optical power, a fifth lens with a positive optical power, a sixth lens with a negative optical power, a seventh lens with a positive optical power, and an eighth lens with a negative optical power. Among the first lens to the eighth lens, the fifth lens has the largest central thickness on the optical axis of the optical imaging system. The spacer element group includes a first spacer element disposed between the first lens and the second lens and in partial contact with the image side surface of the first lens, a second spacer element disposed between the second lens and the third lens and in partial contact with the image side surface of the second lens, a third spacer element disposed between the third lens and the fourth lens and in partial contact with the image side surface of the third lens, a fourth spacer element disposed between the fourth lens and the fifth lens and in partial contact with the image side surface of the fourth lens, a fifth spacer element disposed between the fifth lens and the sixth lens and in partial contact with the image side surface of the fifth lens, a sixth spacer element disposed between the sixth lens and the seventh lens and in partial contact with the image side surface of the sixth lens, and a seventh spacer element disposed between the seventh lens and the eighth lens and in partial contact with the image side surface of the seventh lens. Among them, the air gap T45 between the fourth lens and the fifth lens on the optical axis and the maximum axial thickness CP4 of the fourth spacer element satisfy: 4.50 < T45 / CP4 < 20.98; the inner diameter d4m of the image side surface of the fourth spacer element and the central thickness CT5 of the fifth lens on the optical axis satisfy: 3.21 < d4m / CT5 < 4.

81.

2. The optical imaging system according to claim 1, characterized in that, The effective focal length f4 of the fourth lens and the curvature radius R7 of the object side surface of the fourth lens satisfy: -4.85 < f4 / R7 < -1.62; the effective focal length f4 of the fourth lens and the inner diameter d3m of the image side surface of the third spacer element satisfy: -4.98 < f4 / d3m < -2.

27.

3. The optical imaging system according to claim 1, characterized in that, The air gap T67 between the sixth lens and the seventh lens on the optical axis, the air gap T78 between the seventh lens and the eighth lens on the optical axis, and the spacer distance EP67 on the optical axis from the image side surface of the sixth spacer element to the object side surface of the seventh spacer element satisfy: 0.44 < EP67 / (T78 - T67) < 3.

11.

4. The optical imaging system according to claim 1, characterized in that, Among the adjacent two lenses of the first lens to the eighth lens, the air gap between the seventh lens and the eighth lens on the optical axis is the largest. The inner diameter d7m of the image side surface of the seventh spacer element and the air gap T78 between the seventh lens and the eighth lens on the optical axis satisfy: 5.37 < d7m / T78 < 8.

42.

5. The optical imaging system according to claim 1, characterized in that, The following relationships are satisfied between the outer diameter D1s of the object side surface of the first spacer element and the radius of curvature R2 of the image side surface of the first lens: 1.65 < D1s / R2 < 2.74; the following relationship is satisfied between the radius of curvature R1 of the object side surface of the first lens and the central thickness CT1 of the first lens on the optical axis: 6.85 < R1 / CT1 < 9.

49.

6. The optical imaging system according to claim 1, characterized in that, The following relationship is satisfied between the axial distance EP12 on the optical axis from the image side surface of the first spacer element to the object side surface of the second spacer element and the air gap T23 on the optical axis between the second lens and the third lens: 4.05 < EP12 / T23 < 7.

21.

7. The optical imaging system according to claim 1, characterized in that, The following relationship is satisfied between the inner diameter d2m of the image side surface of the second spacer element and the central thickness CT3 of the third lens on the optical axis: 7.24 < d2m / CT3 < 9.20; the following relationship is satisfied between the effective focal length f3 of the third lens and the inner diameter d2m of the image side surface of the second spacer element: 1.12 < f3 / d2m < 2.

13.

8. The optical imaging system according to claim 1, characterized in that, The following relationship is satisfied between the axial distance EP56 on the optical axis from the image side surface of the fifth spacer element to the object side surface of the sixth spacer element and the central thickness CT6 of the sixth lens on the optical axis: 1.47 < EP56 / CT6 < 4.

58.

9. The optical imaging system according to claim 1, characterized in that, The following relationship is satisfied among the effective focal length f5 of the fifth lens, the central thickness CT5 of the fifth lens on the optical axis, and the maximum axial thickness CP5 of the fifth spacer element: 1.82 < f5 / (CT5 + CP5) < 5.

30.

10. The optical imaging system according to claim 1, characterized in that, The following relationship is satisfied between the axial distance SAG42 on the optical axis from the intersection point of the image side surface of the fourth lens and the optical axis to the effective radius vertex of the image side surface of the fourth lens and the maximum axial thickness CP4 of the fourth spacer element: 11.71 < SAG42 / CP4 < 22.

19.

11. The optical imaging system according to claim 1, characterized in that, The following relationship is satisfied between the inner diameter d6s of the object side surface of the sixth spacer element and the central thickness CT6 of the sixth lens on the optical axis: 10.93 < d6s / CT6 < 17.99; the following relationship is satisfied between the effective focal length f6 of the sixth lens and the outer diameter D6s of the object side surface of the sixth spacer element: -3.06 < f6 / D6s < -1.

95.

12. The optical imaging system according to claim 1, characterized in that, The following relationship is satisfied between the central thickness CT7 of the seventh lens on the optical axis and the axial distance EP67 on the optical axis from the image side surface of the sixth spacer element to the object side surface of the seventh spacer element: 0.83 < CT7 / EP67 < 1.71; the following relationship is satisfied between the effective focal length f7 of the seventh lens and the inner diameter d6m of the image side surface of the sixth spacer element: 1.37 < f7 / d6m < 3.

08.

13. The optical imaging system according to claim 1, characterized in that, The following relationship is satisfied between the axial distance SAG12 on the optical axis from the intersection point of the image side surface of the first lens and the optical axis to the effective radius vertex of the image side surface of the first lens and the maximum axial thickness CP1 of the first spacer element: 16.65 < SAG12 / CP1 < 23.

19.

14. The optical imaging system according to claim 1, characterized in that, The air gap T78 between the seventh lens and the eighth lens on the optical axis and the central thickness CT8 of the eighth lens on the optical axis satisfy: 1.07 < T78 / CT8 < 3.45; the inner diameter d7m of the image side of the seventh spacer element, the air gap T78 between the seventh lens and the eighth lens on the optical axis and the central thickness CT8 of the eighth lens on the optical axis satisfy: 3.58 < d7m / (T78 + CT8) < 4.

47.

15. The optical imaging system according to any one of claims 1 to 14, characterized in that, The spacer element group further includes an eighth spacer element disposed on the image side of the eighth lens and partially contacting the image side surface of the eighth lens.

16. The optical imaging system according to any one of claims 1 to 14, characterized in that, The spacer element group further includes a fifth auxiliary spacer element disposed on the image side of the fifth spacer element and partially contacting the image side surface of the fifth spacer element. The maximum axial thickness CP5 of the fifth spacer element, the maximum axial thickness CP5b of the fifth auxiliary spacer element and the central thickness CT6 of the sixth lens on the optical axis satisfy: 0.82 < (CP5 + CP5b) / CT6 < 3.12.

Images