Optical imaging system

Abstract

The application discloses an optical imaging system, which comprises a lens barrel, an eight-piece lens group and a spacer group arranged in the lens barrel. The eight-piece lens group comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens arranged in sequence along an optical axis from an object side to an image side. The fifth lens and the eighth lens have negative refractive powers. The spacer group comprises a fifth spacer abutting against an image side surface of the fifth lens, a sixth spacer abutting against an image side surface of the sixth lens and a seventh spacer abutting against an image side surface of the seventh lens. The effective focal length f5 of the fifth lens, the interval EP56 of the fifth spacer and the sixth spacer along the optical axis and the air interval T67 of the sixth lens and the seventh lens on the optical axis satisfy the condition: -80 < f5 / (EP56+T67) < -30. The effective focal length f8 of the eighth lens, the interval EP67 of the sixth spacer and the seventh spacer along the optical axis and the air interval T78 of the seventh lens and the eighth lens on the optical axis satisfy the condition: -15 < f8 / (EP67+T78) < 0.

Description

TECHNICAL FIELD

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

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

[0003] In order to meet the requirement of a large image surface, the optical imaging system is usually provided in the form of an eight-piece lens structure. In the eight-piece optical imaging system, there is a large step difference between the lenses close to the image side, which can cause the assembly stability and assembly yield of the optical imaging system to be poor, thereby affecting the product competitiveness of the optical imaging system. SUMMARY

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

[0005] An aspect of the present application provides an optical imaging system, which includes a lens barrel, an eight-piece lens group and a spacer group arranged in the lens barrel. The eight-piece lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens arranged in order along an optical axis from an object side to an image side. The fifth lens and the eighth lens both have negative refractive power. The spacer group includes a fifth spacer abutting against an image side surface of the fifth lens, a sixth spacer abutting against an image side surface of the sixth lens, and a seventh spacer abutting against an image side surface of the seventh lens. An effective focal length f5 of the fifth lens, a spacing EP56 between the fifth spacer and the sixth spacer along the optical axis, and an air spacing T67 of the sixth lens and the seventh lens on the optical axis satisfy: -80 < f5 / (EP56+T67) < -30. An effective focal length f8 of the eighth lens, a spacing EP67 between the sixth spacer and the seventh spacer along the optical axis, and an air spacing T78 of the seventh lens and the eighth lens on the optical axis satisfy: -15 < f8 / (EP67+T78) < 0.

[0006] According to an example embodiment of the present application, the group of spacers further comprises a second spacer abutting the image side surface of the second lens, wherein the second lens and the third lens both have negative refractive powers, and the effective focal length f2 of the second lens, the inner diameter d2s of the object side surface of the second spacer, and the outer diameter D2s of the object side surface of the second spacer satisfy: -20 < f2 / (D2s-d2s) < 0, and the effective focal length f3 of the third lens, the inner diameter d2s of the object side surface of the second spacer, and the outer diameter D2s of the object side surface of the second spacer satisfy: -92 < f3 / (D2s+d2s) < -15.

[0007] According to an example embodiment of the present application, the combined focal length f78 of the seventh lens and the eighth lens, the air separation T78 of the seventh lens and the eighth lens on the optical axis, the central thickness CT8 of the eighth lens on the optical axis, and the maximum thickness CP7 of the seventh spacer satisfy: 10 < f78 / (CP7+T78+CT8) < 35.

[0008] According to an example embodiment of the present application, the group of spacers further comprises a third spacer abutting the image side surface of the third lens and a fourth spacer abutting the image side surface of the fourth lens, wherein the fourth lens has positive refractive power, and both the object side surface and the image side surface of the fourth lens are convex at the paraxial region, and the curvature radius R7 of the object side surface of the fourth lens, the curvature radius R8 of the image side surface of the fourth lens, the inner diameter d3s of the object side surface of the third spacer, and the interval EP34 of the third spacer and the fourth spacer along the optical axis satisfy: -46 < d3s / R7+R8 / EP34 < -15.

[0009] According to an example embodiment of the present application, the group of spacers further comprises a third spacer abutting the image side surface of the third lens and a fourth spacer abutting the image side surface of the fourth lens, wherein the effective focal length f4 of the fourth lens, the air separation T34 of the third lens and the fourth lens on the optical axis, the outer diameter D3m of the image side surface of the third spacer, and the inner diameter d4m of the image side surface of the fourth spacer satisfy: 85 < (f4 / d4m) x (D3m / T34) < 185.

[0010] According to an example embodiment of the present application, the effective focal length f6 of the sixth lens, the effective focal length f7 of the seventh lens, the inner diameter d6m of the image side surface of the sixth spacer, and the outer diameter D6m of the image side surface of the sixth spacer satisfy: -20 < (f6+f7) / (D6m-d6m) < 0.

[0011] According to an example embodiment of the present application, the inner diameter d0m of the image side end surface of the lens barrel, the total effective focal length f of the optical imaging system, and half of the maximum field angle Semi-FOV of the optical imaging system satisfy: 0 < d0m / (f x tan(Semi-FOV)) < 2.

[0012] According to one example embodiment of the present application, the spacer group further includes a first spacer abutting against the image side surface of the first lens, a second spacer abutting against the image side surface of the second lens, and a third spacer abutting against the image side surface of the third lens, wherein the minimum value minVa of the Abbe number of all of the first to third lenses, the interval EP12 of the first and second spacers along the optical axis, and the interval EP23 of the second and third spacers along the optical axis satisfy: 12 mm -1 <minVa / (EP12+EP23)<24mm -1 , the minimum value minVb of the Abbe number of all of the sixth to eighth lenses, the interval EP67 of the sixth and seventh spacers along the optical axis, and the air interval T78 of the seventh and eighth lenses on the optical axis satisfy: 20 mm -1 <minVb / (EP67+T78)<41mm -1 .

[0013] According to one example embodiment of the present application, the spacer group further includes a first spacer abutting against the image side surface of the first lens, a second spacer abutting against the image side surface of the second lens, and a third spacer abutting against the image side surface of the third lens, wherein the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens, the inner diameter d1s of the object side surface of the first spacer, the inner diameter d2s of the object side surface of the second spacer, and the inner diameter d3s of the object side surface of the third spacer satisfy: |f1 / d1s|<|f2 / d2s|<|f3 / d3s|.

[0014] According to one example embodiment of the present application, the radius of curvature R9 of the object side surface of the fifth lens, the radius of curvature R10 of the image side surface of the fifth lens, and the outer diameter D5s of the object side surface of the fifth spacer satisfy: 0<(R9-R10) / D5s<12, and the radius of curvature R11 of the object side surface of the sixth lens, the radius of curvature R12 of the image side surface of the sixth lens, and the inner diameter d5s of the object side surface of the fifth spacer satisfy: -3<(R11+R12) / d5s<0.

[0015] According to one example embodiment of the present application, the inner diameter d7m of the image side surface of the seventh spacer, the outer diameter D7m of the image side surface of the seventh spacer, the radius of curvature R15 of the object side surface of the eighth lens, and the radius of curvature R16 of the image side surface of the eighth lens satisfy: 10<(D7m+d7m) / (R15-R16)<25.

[0016] According to an example embodiment of the present application, the spacer set further comprises a first spacer abutting against the image side surface of the first lens, wherein the radius of curvature R1 of the object side surface of the first lens, the radius of curvature R3 of the object side surface of the second lens, the inner diameter d1m of the image side surface of the first spacer, and the outer diameter D1m of the image side surface of the first spacer satisfy: 0 < (D1m x R1) / (R3 x d1m) < 2.

[0017] According to an example embodiment of the present application, the spacer set further comprises a first spacer abutting against the image side surface of the first lens, wherein the effective focal length f1 of the first lens, the entrance pupil diameter EPD of the optical imaging system, and the interval EP01 of the object side end surface of the lens barrel and the first spacer along the optical axis satisfy: 20 mm < f1 / EP01 x EPD < 41 mm.

[0018] According to an example embodiment of the present application, the spacer set further comprises a first spacer abutting against the image side surface of the first lens and a second spacer abutting against the image side surface of the second lens, wherein the radius of curvature R2 of the image side surface of the first lens, the air interval T12 of the first lens and the second lens along the optical axis, and the maximum thickness CP1 of the first spacer satisfy: 81 < R2 / (CP1 + T12) < 110, and the radius of curvature R4 of the image side surface of the second lens, the central thickness CT2 of the second lens along the optical axis, and the interval EP12 of the first spacer and the second spacer along the optical axis satisfy: 1 < R4 / (EP12 + CT2) < 5.

[0019] The optical imaging system provided by the present application is an eight-piece large image surface optical system. When the lens and the spacer are not reasonably matched in space, problems such as poor light transmission effect, stray light, and poor assembly stability are prone to occur. By controlling the mutual relationship between the effective focal length of the fifth lens, the interval of the fifth spacer and the sixth spacer along the optical axis, and the air interval of the sixth lens and the seventh lens along the optical axis, the present application can realize large-step transition of the sixth lens and the seventh lens, so that the sixth lens and the seventh lens are stably abutted, the assembly stability and yield of the optical imaging system are improved, and by controlling the mutual relationship between the effective focal length of the eighth lens, the interval of the sixth spacer and the seventh spacer along the optical axis, and the air interval of the seventh lens and the eighth lens along the optical axis, the present application can ensure that the light is quickly turned when it is turned from the seventh lens to the eighth lens, and accurately irradiated on the specified area of the imaging surface, so as to ensure the rationality of the fluctuation of the optical parameters of the optical imaging system. BRIEF DESCRIPTION OF DRAWINGS

[0020] Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the following drawings:

[0021] Figure 1A structural diagram of an optical imaging system according to the present application is shown;

[0022] Figure 2 A structural diagram of an optical imaging system according to the first embodiment of the present application is shown;

[0023] Figure 3 A structural diagram of an optical imaging system according to the second embodiment of the present application is shown;

[0024] Figure 4 A structural diagram of an optical imaging system according to the third embodiment of the present application is shown;

[0025] Figures 5A to 5D Axial chromatic aberration curves, astigmatism curves, distortion curves and magnification chromatic aberration curves of the optical imaging system according to the first embodiment of the present application are shown, respectively;

[0026] Figure 6 A structural diagram of an optical imaging system according to the first embodiment of the present application is shown;

[0027] Figure 7 A structural diagram of an optical imaging system according to the second embodiment of the present application is shown;

[0028] Figure 8 A structural diagram of an optical imaging system according to the third embodiment of the present application is shown;

[0029] Figures 9A to 9D Axial chromatic aberration curves, astigmatism curves, distortion curves and magnification chromatic aberration curves of the optical imaging system according to the second embodiment of the present application are shown, respectively;

[0030] Figure 10 A structural diagram of an optical imaging system according to the first embodiment of the present application is shown;

[0031] Figure 11 A structural diagram of an optical imaging system according to the second embodiment of the present application is shown;

[0032] Figure 12 A structural diagram of an optical imaging system according to the third embodiment of the present application is shown; and

[0033] Figures 13A to 13D Axial chromatic aberration curves, astigmatism curves, distortion curves and magnification chromatic aberration curves of the optical imaging system according to the third embodiment of the present application are shown, respectively. DETAILED DESCRIPTION

[0034] For a better understanding of the present application, various aspects of the present application will be presented in more detail by referring to the attached drawings. It should be noted that these detailed description is merely a description of exemplary embodiments of the present application, and does not limit the scope of the present application in any way. Throughout the specification, like drawing reference numerals will be used to refer to like elements throughout the specification.

[0035] It should be noted that the terms first, second, third, etc. in the present specification are merely used to distinguish one feature from another, and do not represent any limitation on the features. Thus, the first lens discussed below can also be referred to as the second lens or the third lens without departing from the teachings of the present application.

[0036] In the drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shape of the spherical or aspherical surface shown in the drawings is shown by way of example. That is, the shape of the spherical or aspherical surface is not limited to the shape of the spherical or aspherical surface shown in the drawings. The drawings are merely examples and are not drawn strictly to scale.

[0037] In the present specification, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region. If the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object side is referred to as the object side surface of the lens, and the surface of each lens closest to the image side is referred to as the image side surface of the lens.

[0038] It should also be understood that the terms "comprise", "comprising", "have", "having", "include" and / or "including" when used in this specification, mean the presence of stated features, elements and / or components but do not preclude the presence or addition of one or more other features, elements, components and / or groups thereof. In addition, when describing the embodiments of the present application, the use of "may" means "one or more embodiments of the present application". Also, the term "exemplary" is intended to mean an example or an illustration.

[0039] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that the terms should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0040] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in more detail below with reference to the drawings and in conjunction with the embodiments.

[0041] The features, principles, and other aspects of the present application are described in detail below.

[0042] As shown in FIGS. Figures 2 to 4 , Figures 6 to 8 and Figures 10 to 12 , the optical imaging system according to the exemplary embodiments of the present application can be, for example, an eight-piece large-format optical system including a lens barrel and an eight-piece lens group disposed in the lens barrel, which can include, in order from the object side to the image side along the optical axis, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens. Among the first lens to the eighth lens, any two adjacent lenses can have an air gap therebetween. The fifth lens and the sixth lens each have a negative refractive power.

[0043] The optical imaging system can further include a spacer group disposed in the lens barrel, which can include a fifth spacer abutting against the image side surface of the fifth lens, a sixth spacer abutting against the image side surface of the sixth lens, and a seventh spacer abutting against the image side surface of the seventh lens. The lenses and the spacers in the optical imaging system are easily misaligned in space, which can cause the optical imaging system to have poor light transmission, flare, poor assembly stability, and the like. Therefore, in an example, the effective focal length f5 of the fifth lens, the interval EP56 of the fifth spacer and the sixth spacer along the optical axis, and the air gap T67 of the sixth lens and the seventh lens along the optical axis can satisfy -80 < f5 / (EP56+T67) < -30, and the effective focal length f8 of the eighth lens, the interval EP67 of the sixth spacer and the seventh spacer along the optical axis, and the air gap T78 of the seventh lens and the eighth lens along the optical axis can satisfy -15 < f8 / (EP67+T78) < 0. As an example, -11 < f8 / (EP67+T78) < -6. By controlling the mutual relationship between the effective focal length of the fifth lens, the interval of the fifth spacer and the sixth spacer along the optical axis, and the air gap of the sixth lens and the seventh lens along the optical axis, a large step transition of the sixth lens and the seventh lens can be achieved, so that the sixth lens and the seventh lens are stably abutted against each other, the assembly stability and the assembly yield of the optical imaging system are improved, and by controlling the mutual relationship between the effective focal length of the eighth lens, the interval of the sixth spacer and the seventh spacer along the optical axis, and the air gap of the seventh lens and the eighth lens along the optical axis, the light rays can be quickly turned when passing through the seventh lens to the eighth lens, and accurately irradiated on the specified region of the imaging surface, so as to ensure the rationality of the fluctuation of the optical parameters of the optical imaging system.

[0044] In other examples, the spacer set can further include one or more of a first spacer, a second spacer, a third spacer, and a fourth spacer. The first spacer abuts the image side surface of the first lens; the second spacer abuts the image side surface of the second lens; the third spacer abuts the image side surface of the third lens; and the fourth spacer abuts the image side surface of the fourth lens. Reasonable use of the spacers can effectively avoid stray light risks, reduce interference with image quality, and thus improve the imaging quality of the optical imaging system.

[0045] In example embodiments, the second lens and the third lens each have a negative optical power. The effective focal length f2 of the second lens, the inner diameter d2s of the object side surface of the second spacer, and the outer diameter D2s of the object side surface of the second spacer can satisfy -20 < f2 / (D2s-d2s) < 0, and the effective focal length f3 of the third lens, the inner diameter d2s of the object side surface of the second spacer, and the outer diameter D2s of the object side surface of the second spacer can satisfy -92 < f3 / (D2s+d2s) < -15. By making the optical powers of the second lens and the third lens negative and constraining the sizes of the inner and outer diameters of the object side surface of the second spacer, the light rays can be ensured to diverge within a reasonable range when passing through the second lens and the third lens, thereby improving the performance and imaging quality of the optical imaging system.

[0046] In example embodiments, the combined focal length f78 of the seventh lens and the eighth lens, the air separation T78 of the seventh lens and the eighth lens on the optical axis, the central thickness CT8 of the eighth lens on the optical axis, and the maximum thickness CP7 of the seventh spacer can satisfy 10 < f78 / (CP7+T78+CT8) < 35. Reasonable control of the mutual relationship between the combined focal length of the seventh lens and the eighth lens, the air separation of the seventh lens and the eighth lens on the optical axis, the central thickness of the eighth lens on the optical axis, and the maximum thickness of the seventh spacer can ensure that the light rays are quickly turned when passing through the seventh lens and turning to the eighth lens, and accurately irradiate to the specified area of the imaging surface, to ensure the reasonable fluctuation of the optical parameters of the optical imaging system, while the light rays are normally turned over between the seventh lens and the eighth lens, which can effectively improve the stability of the optical imaging system.

[0047] In an example embodiment, the fourth lens has positive refractive power, and both the object side surface and the image side surface of the fourth lens are convex at the paraxial region. Moreover, the curvature radius R7 of the object side surface of the fourth lens, the curvature radius R8 of the image side surface of the fourth lens, the inner diameter d3s of the object side surface of the third spacer, and the interval EP34 of the third spacer and the fourth spacer along the optical axis can satisfy: -46 < d3s / R7 + R8 / EP34 < -15. In an example, -40 < d3s / R7 + R8 / EP34 < -20. Reasonably controlling the mutual relationship among the curvature radius of the object side surface and the image side surface of the fourth lens, the inner diameter of the object side surface of the third spacer, and the interval of the third spacer and the fourth spacer along the optical axis can ensure that the bending angle of the light passing through the fourth lens is within a reasonable range, and reduce the stray light generated by the fourth lens due to insufficient light blocking of the spacer.

[0048] In an example embodiment, the effective focal length f4 of the fourth lens, the air interval T34 of the third lens and the fourth lens along the optical axis, the outer diameter D3m of the image side surface of the third spacer, and the inner diameter d4m of the image side surface of the fourth spacer can satisfy: 85 < (f4 / d4m) x (D3m / T34) < 185. Reasonably controlling the mutual relationship among the effective focal length of the fourth lens, the air interval of the third lens and the fourth lens along the optical axis, the outer diameter of the image side surface of the third spacer, and the inner diameter of the image side surface of the fourth spacer can effectively limit the size of the third lens, the fourth lens, the third spacer, and the fourth spacer, improve the manufacturability and processing stability of the above lenses and spacers, and thus ensure the product quality consistency of the optical imaging system.

[0049] In an example embodiment, the effective focal length f6 of the sixth lens, the effective focal length f7 of the seventh lens, the inner diameter d6m of the image side surface of the sixth spacer, and the outer diameter D6m of the image side surface of the sixth spacer can satisfy: -20 < (f6 + f7) / (D6m - d6m) < 0. In an example, -18 < (f6 + f7) / (D6m - d6m) < -5. Reasonably controlling the mutual relationship among the effective focal length of the sixth lens, the effective focal length of the seventh lens, the inner diameter of the image side surface of the sixth spacer, and the outer diameter of the image side surface of the sixth spacer can effectively constrain the size of the sixth lens, the sixth spacer, and the seventh lens, block the excess light entering the seventh lens, and reduce the risk of stray light generated by the seventh lens.

[0050] In the example embodiment, the inner diameter d0m of the image-side end surface of the lens barrel, the total effective focal length f of the optical imaging system, and the half of the maximum field angle Semi-FOV of the optical imaging system can satisfy: 0 < d0m / (f x tan(Semi-FOV)) < 2. Reasonably controlling the mutual relationship between the inner diameter of the image-side end surface of the lens barrel, the total effective focal length of the optical imaging system, and the half of the maximum field angle of the optical imaging system can constrain the inner diameter of the image-side end surface of the lens barrel within a reasonable range, avoid the image-side end surface of the lens barrel from blocking light, and thus reduce the insufficient light flux and poor performance caused by tolerance fluctuation.

[0051] In the example embodiment, the minimum value minVa of the Abbe number of all the lenses in the first lens to the third lens, the interval EP12 of the first spacer and the second spacer along the optical axis, and the interval EP23 of the second spacer and the third spacer along the optical axis can satisfy: 12mm -1 <minVa / (EP12+EP23)<24mm -1 , and the minimum value minVb of the Abbe number of all the lenses in the sixth lens to the eighth lens, the interval EP67 of the sixth spacer and the seventh spacer along the optical axis, and the air interval T78 of the seventh lens and the eighth lens along the optical axis can satisfy: 20mm -1 <minVb / (EP67+T78)<41mm -1 . As an example, in the first lens to the third lens, the Abbe number of the third lens is the smallest; in the sixth lens to the eighth lens, the Abbe number of the sixth lens is the smallest. In the example, 15mm -1 <minVa / (EP12+EP23)<20mm -1 , 23mm -1 <minVb / (EP67+T78)<37.5mm -1 . By controlling the above conditional expressions, the dispersion degree of light when passing through each lens can be controlled, the contrast and resolution of the optical imaging system are improved, and the optical imaging system has the best imaging effect.

[0052] In the example embodiments, the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens, the inner diameter d1s of the object side surface of the first spacer, the inner diameter d2s of the object side surface of the second spacer, and the inner diameter d3s of the object side surface of the third spacer can satisfy: |f1 / d1s|<|f2 / d2s|<|f3 / d3s|. By restricting the ratio of the effective focal length of each lens in the first lens to the third lens to the inner diameter of the object side surface of the corresponding spacer within a reasonable range, the light throughput of the optical imaging system can be maintained at a constant level, the energy loss of light when refracted by the lens is minimized, the exposure of the entire optical imaging system is improved, and the overall imaging of the optical imaging system is full and sufficient.

[0053] In the example embodiments, the radius of curvature R9 of the object side surface of the fifth lens, the radius of curvature R10 of the image side surface of the fifth lens, and the outer diameter D5s of the object side surface of the fifth spacer can satisfy: 0<(R9-R10) / D5s<12, and the radius of curvature R11 of the object side surface of the sixth lens, the radius of curvature R12 of the image side surface of the sixth lens, and the inner diameter d5s of the object side surface of the fifth spacer can satisfy: -3<(R11+R12) / d5s<0. In an example, 2<(R9-R10) / D5s<8.5, and -1.8<(R11+R12) / d5s<-1. By controlling the above conditions, the structural uniformity of the fifth lens and the sixth lens and the processability of the fifth spacer can be ensured, and the fifth spacer can also block the stray light generated between the fifth lens and the sixth lens, thereby improving the imaging picture quality of the optical imaging system.

[0054] In the example embodiments, the inner diameter d7m of the image side surface of the seventh spacer, the outer diameter D7m of the image side surface of the seventh spacer, the radius of curvature R15 of the object side surface of the eighth lens, and the radius of curvature R16 of the image side surface of the eighth lens can satisfy: 10<(D7m+d7m) / (R15-R16)<25. In an example, 15<(D7m+d7m) / (R15-R16)<20. By reasonably controlling the mutual relationship between the inner and outer diameters of the image side surface of the seventh spacer and the radii of curvature of the object side surface and the image side surface of the eighth lens, the relative position of the eighth lens and the seventh spacer can be effectively limited, the number of light rays that bypass the seventh spacer and irradiate to the mechanism part of the eighth lens can be reduced, and the stray light generated by the light rays irradiating to the mechanism part of the eighth lens can be reduced.

[0055] In the example embodiment, the radius of curvature R1 of the object side surface of the first lens, the radius of curvature R3 of the object side surface of the second lens, the inner diameter d1m of the image side surface of the first spacer, and the outer diameter D1m of the image side surface of the first spacer can satisfy: 0 < (D1m x R1) / (R3 x d1m) < 2. In an example, 0.6 < (D1m x R1) / (R3 x d1m) < 1. Reasonably controlling the mutual relationship between the radius of curvature of the object side surface of the first lens, the radius of curvature of the object side surface of the second lens, and the inner and outer diameters of the image side surface of the first spacer can constrain the shape of the first lens and the second lens while ensuring the processability of the first spacer, ensuring that the processability and formability of the first lens and the second lens are in the optimal state.

[0056] In the example embodiment, the effective focal length f1 of the first lens, the entrance pupil diameter EPD of the optical imaging system, and the interval EP01 of the object side end surface of the lens barrel and the first spacer along the optical axis can satisfy: 20 mm < f1 / EP01 x EPD < 41 mm. In an example, 24 mm < f1 / EP01 x EPD < 38 mm. Reasonably controlling the mutual relationship between the effective focal length of the first lens, the entrance pupil diameter of the optical imaging system, and the interval of the object side end surface of the lens barrel and the first spacer along the optical axis can make the light aperture fluctuate within a certain range when passing through the first spacer, ensuring that the luminous flux of the optical imaging system is in the optimal state to meet the imaging requirements of the optical imaging system.

[0057] In the example embodiment, the radius of curvature R2 of the image side surface of the first lens, the air interval T12 of the first lens and the second lens along the optical axis, and the maximum thickness CP1 of the first spacer can satisfy: 81 < R2 / (CP1 + T12) < 110, and the radius of curvature R4 of the image side surface of the second lens, the central thickness CT2 of the second lens along the optical axis, and the interval EP12 of the first spacer and the second spacer along the optical axis can satisfy: 1 < R4 / (EP12 + CT2) < 5. In an example, 2.8 < R4 / (EP12 + CT2) < 4. By controlling the above conditional expressions, the energy of the light passing through the first spacer and the second spacer can be limited, the deflection direction and degree of the light at the first lens and the second lens can be constrained, the light can be ensured to propagate to the imaging surface according to the designed inherent path, the stray light affecting the imaging of the optical imaging system can be avoided, the imaging state of the optical imaging system can be optimized, and the imaging quality of the optical imaging system can be improved.

[0058] In the example embodiment, the optical imaging system can further include a diaphragm arranged between the object side and the first lens.

[0059] The optical imaging system according to the above-mentioned embodiments of the present application can adopt eight lenses and multiple spacers. By reasonably allocating the parameters of each lens and each spacer, the risk of stray light of the optical imaging system can be reduced, the assembly stability and imaging quality of the optical imaging system can be improved, and the stable imaging capability of the optical imaging system can be ensured.

[0060] In the embodiments of the present application, at least one of the mirror surfaces of each lens in the first lens to the eighth lens is a non-spherical mirror surface. The non-spherical lens has the characteristic that the curvature continuously changes from the center of the lens to the periphery of the lens. Unlike the spherical lens which has a constant curvature from the center of the lens to the periphery of the lens, the non-spherical lens has better curvature radius characteristics, has the advantages of improving the distortion aberration and improving the astigmatism aberration. After using the non-spherical lens, the aberration that occurs during imaging can be eliminated as much as possible, thereby improving the imaging quality. Alternatively, the object side surface and the image side surface of each lens in the first lens to the eighth lens are non-spherical mirror surfaces.

[0061] However, those skilled in the art should understand that the number of lenses and spacers constituting the optical imaging system can be changed without departing from the technical solutions claimed by the present application, to obtain the various results and advantages described in the present specification.

[0062] The specific embodiments of the optical imaging system applicable to the above-mentioned embodiments will be further described below with reference to the accompanying drawings.

[0063] First embodiment

[0064] The following refers to Figures 2 to 5D The optical imaging system according to the first embodiment of the present application is described. Figure 2 The structural schematic diagram of the optical imaging system 110 according to the first embodiment of the present application is shown; Figure 3 The structural schematic diagram of the optical imaging system 120 according to the second embodiment of the present application is shown; Figure 4 The structural schematic diagram of the optical imaging system 130 according to the third embodiment of the present application is shown.

[0065] As Figures 2 to 4As shown, the optical imaging system 110, 120, 130 each includes a lens barrel, and an eight-piece lens group and a spacer group disposed in the lens barrel. The eight-piece lens group includes, in order from the object side to the image side, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, and an eighth lens E8. A stop STO can be disposed between the object side and the first lens E1. The spacer group includes a first spacer P1, a second spacer P2, a third spacer P3, a fourth spacer P4, a fifth spacer P5, a sixth spacer P6, and a seventh spacer P7. The spacers can block extraneous light in the imaging process from entering the next lens, so that the lens and the lens barrel are better supported, and the structural stability of the optical imaging system is enhanced.

[0066] The first lens E1 has a positive focal power, with a convex object side surface S1 and a concave image side surface S2. The second lens E2 has a negative focal power, with a convex object side surface S3 and a concave image side surface S4. The third lens E3 has a negative focal power, with a convex object side surface S5 and a concave image side surface S6. The fourth lens E4 has a positive focal power, with a convex object side surface S7 and a convex image side surface S8. The fifth lens E5 has a negative focal power, with a concave object side surface S9 and a convex image side surface S10. The sixth lens E6 has a negative focal power, with a concave object side surface S11 and a convex image side surface S12. The seventh lens E7 has a positive focal power, with a convex object side surface S13 and a concave image side surface S14. The eighth lens E8 has a negative focal power, with a convex object side surface S15 and a concave image side surface S16. The filter has an object side surface S17 (not shown) and an image side surface S18 (not shown). Light from the object passes through the surfaces S1 to S18 in order and is ultimately imaged on an imaging surface S19 (not shown).

[0067] Table 1 shows a basic parameter table of the optical imaging system of the first embodiment, where the units of the curvature radius, the thickness / distance, and the focal length are all millimeters (mm).

[0068]

[0069] Table 1

[0070] In the present embodiment, the total effective focal length f of the optical imaging system has a value of 7.10 mm, the half of the maximum field of view angle Semi-FOV of the optical imaging system has a value of 39.54°, the entrance pupil diameter EPD of the optical imaging system has a value of 4.03 mm, and the combined focal length f78 of the seventh lens and the eighth lens has a value of 23.28 mm.

[0071] In the first embodiment, the object side surface and the image side surface of any one of the first lens E1 to the eighth lens E8 are aspherical surfaces, and the surface type x of each aspherical surface can be defined by, but is not limited to, the following aspherical surface formula:

[0072]

[0073] Where x is the distance vector from the vertex of the aspherical surface at a height of h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 2 gives the higher-order coefficients A4, A6, A8, A16, A26, A36, A47, A68, A166 that can be used for each aspherical mirror S1-S16 in the first embodiment. 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 and A 30 .

[0074] Face number A4 A6 A8 A10 A12 A14 A16 S1 4.6799E-02 3.5585E-03 -1.9290E-03 -1.4773E-03 -6.9666E-04 -3.2342E-04 -1.3580E-04 S2 -1.1077E-02 3.0465E-03 -3.6985E-03 -1.3374E-04 -5.4059E-04 -6.6992E-05 -5.5306E-05 S3 -8.8002E-02 2.6654E-02 1.9719E-03 1.2481E-03 -2.3336E-04 6.2636E-05 -8.6315E-06 S4 -3.8188E-02 2.3298E-02 7.2994E-03 2.7540E-03 7.3334E-04 2.1721E-04 3.1884E-05 S5 -1.7321E-01 2.2131E-04 3.7165E-03 4.6414E-04 -5.0900E-04 -2.4179E-04 -1.1732E-04 S6 -2.0724E-01 2.1333E-02 3.7889E-03 -1.3316E-03 -1.4789E-03 -3.8415E-04 -1.9338E-04 S7 -2.3506E-01 2.0046E-02 5.5318E-03 3.9415E-03 1.8148E-03 4.9379E-04 -3.4625E-04 S8 -4.3768E-01 1.6472E-02 8.2255E-03 7.7788E-03 5.3212E-03 2.3349E-03 7.7745E-04 S9 -5.3136E-01 1.2654E-01 2.0933E-02 -5.1847E-03 -1.5244E-03 -1.1139E-03 -1.1338E-04 S10 -5.4304E-01 2.2765E-02 4.3218E-02 5.0598E-03 -1.9570E-03 -1.3916E-03 -6.9761E-04 S11 3.9077E-01 -1.4721E-01 4.1404E-02 1.4819E-02 -5.0293E-04 3.3438E-03 -3.2383E-05 S12 1.8017E-01 2.1229E-01 -3.7980E-02 7.0689E-03 -7.0131E-03 3.5256E-03 9.4992E-04 S13 -2.4871E+00 5.2994E-02 1.6144E-01 -4.0685E-02 7.2867E-03 -2.9588E-03 1.1405E-02 S14 -8.9690E-01 -1.4040E-01 2.1594E-01 -1.5837E-01 7.3018E-02 -1.2886E-02 1.6846E-02 S15 -5.5419E+00 1.6550E+00 -5.8790E-01 1.9964E-01 -5.9505E-02 6.3605E-03 2.1948E-03 S16 -9.4103E+00 2.0397E+00 -6.9057E-01 3.1186E-01 -1.5612E-01 5.0321E-02 -2.9657E-02 Face number A18 A20 A22 A24 A26 A28 A30 S1 -7.2172E-05 -2.6840E-05 -1.3874E-05 2.4735E-06 7.1204E-06 7.4034E-06 9.6591E-07 S2 -6.0309E-06 2.6323E-06 -2.9078E-06 7.9866E-06 4.6166E-06 9.9446E-06 -1.4238E-06 S3 4.0262E-05 9.0385E-06 9.8602E-06 -3.4319E-06 1.8666E-06 2.2501E-06 2.7444E-06 S4 1.0884E-06 -1.1065E-05 -6.9792E-06 -5.3210E-06 -4.3295E-06 -2.5847E-06 -1.5436E-06 S5 -5.6586E-05 -3.8752E-05 -1.7359E-05 -6.5620E-06 -1.1269E-07 1.0445E-07 2.9453E-06 S6 -1.0178E-04 -5.6587E-05 -1.1227E-05 7.2915E-07 2.5852E-06 -2.5726E-06 -1.0710E-06 S7 -4.0635E-04 -2.0689E-04 -4.4459E-05 1.7303E-05 2.1826E-05 8.7373E-06 -2.9954E-06 S8 1.1831E-04 -7.1562E-05 -8.4919E-05 -5.8135E-05 -3.2294E-05 -1.0792E-05 -3.1867E-06 S9 3.0656E-04 3.5346E-05 1.6984E-05 -4.7555E-05 -1.1913E-05 -2.7497E-06 3.4521E-06 S10 1.0241E-04 -1.8070E-04 1.3928E-04 6.7622E-07 1.1544E-05 -9.6320E-06 2.2374E-06 S11 9.8698E-04 -1.0720E-03 -1.9257E-04 -1.6989E-04 6.5239E-05 -2.1566E-05 2.5408E-05 S12 9.3094E-05 -1.0752E-03 1.3984E-04 2.2627E-04 -5.9334E-05 -9.8221E-05 4.1237E-05 S13 -4.8340E-03 -3.1560E-03 -1.2017E-03 1.6940E-03 2.3381E-04 -4.8313E-05 -6.6370E-05 S14 -1.0068E-02 2.5272E-03 -2.1914E-03 1.6965E-03 -9.5451E-04 3.7992E-04 -6.1862E-05 S15 -1.9387E-03 -2.5908E-03 1.6037E-03 1.8660E-04 -2.0744E-03 1.5669E-03 -5.9083E-04 S16 1.2638E-02 -8.3782E-03 1.1881E-03 -4.0697E-03 4.6646E-05 -5.3075E-04 1.0503E-04

[0075] Table 2

[0076] Figure 5A The on-axis chromatic aberration curves of the optical imaging systems 110, 120 and 130 of the first embodiment are shown, which represent the deflection of the focal point after light of different wavelengths passes through the optical imaging systems 110, 120 and 130. Figure 5B Astigmatism curves of the optical imaging systems 110, 120, and 130 of the first embodiment are shown, representing the meridional and sagittal image plane curvatures corresponding to different image heights. Figure 5C The distortion curves of the optical imaging systems 110, 120 and 130 of the first embodiment are shown, which represent the distortion magnitude values ​​corresponding to different image heights. Figure 5D The magnification chromatic aberration curves of the optical imaging systems 110, 120, and 130 of the first embodiment are shown, representing the deviations in image height at different points on the imaging plane after light passes through the system. According to... Figures 5A to 5D It can be seen that the optical imaging systems 110, 120 and 130 given in the first embodiment can achieve good imaging quality.

[0077] Second embodiment

[0078] The following is for reference Figures 6 to 9D An optical imaging system according to a second embodiment of this application is described. Figure 6 A schematic diagram of the structure of an optical imaging system 210 according to Embodiment 1 of the second embodiment of this application is shown; Figure 7A structural schematic diagram of the optical imaging system 220 according to the embodiment 2 of the second embodiment of the present application is shown; Figure 8 A structural schematic diagram of the optical imaging system 230 according to the embodiment 3 of the second embodiment of the present application is shown.

[0079] As shown in Figures 6 to 8 the optical imaging systems 210, 220, and 230 each include a lens barrel, and an eight-piece lens group and a spacer group disposed in the lens barrel. The eight-piece lens group includes, in order from the object side to the image side, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, and an eighth lens E8. A stop STO can be disposed between the object side and the first lens E1. The spacer group includes a first spacer P1, a second spacer P2, a third spacer P3, a fourth spacer P4, a fifth spacer P5, a sixth spacer P6, and a seventh spacer P7. The spacers can block excess light rays in the imaging process from entering the next lens, so that the lens and the lens barrel are better supported, and the structural stability of the optical imaging system is enhanced.

[0080] The first lens E1 has a positive focal power, with a convex object side surface S1 and a concave image side surface S2. The second lens E2 has a negative focal power, with a convex object side surface S3 and a concave image side surface S4. The third lens E3 has a negative focal power, with a convex object side surface S5 and a concave image side surface S6. The fourth lens E4 has a positive focal power, with a convex object side surface S7 and a convex image side surface S8. The fifth lens E5 has a negative focal power, with a concave object side surface S9 and a convex image side surface S10. The sixth lens E6 has a negative focal power, with a concave object side surface S11 and a convex image side surface S12. The seventh lens E7 has a positive focal power, with a convex object side surface S13 and a convex image side surface S14. The eighth lens E8 has a negative focal power, with a convex object side surface S15 and a concave image side surface S16. The filter has an object side surface S17 (not shown) and an image side surface S18 (not shown). Light from the object passes through the surfaces S1 to S18 in order and is finally imaged on an imaging surface S19 (not shown).

[0081] Table 3 shows a table of basic parameters of the optical imaging system of the second embodiment, where the units of the curvature radius, the thickness / distance, and the focal length are all millimeters (mm).

[0082]

[0083]

[0084] Table 3

[0085] In the embodiment, the total effective focal length f of the optical imaging system is 8.88mm, the half of the maximum field of view angle Semi-FOV of the optical imaging system is 38.46°, the entrance pupil diameter EPD of the optical imaging system is 5.04mm, and the combined focal length f78 of the seventh lens and the eighth lens is 16.80mm.

[0086] In the second embodiment, the object side and the image side of any one of the first lens E1 to the eighth lens E8 are aspherical surfaces. Table 4 shows the high order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28, A30, A32, A34, and A36 of the aspherical surfaces S1-S16 which can be used in the second embodiment. 10 12 14 16 18 20 22 24 26 28 30 .

[0087]

[0088]

[0089] Table 4

[0090] Figure 9A The on-axis chromatic aberration curves of the optical imaging systems 210, 220 and 230 of the second embodiment are shown, which represent the convergence focus deviation of light rays of different wavelengths after passing through the optical imaging systems 210, 220 and 230. Figure 9B The astigmatism curves of the optical imaging systems 210, 220 and 230 of the second embodiment are shown, which represent the meridional image surface curvature and sagittal image surface curvature corresponding to different image heights. Figure 9C The distortion curves of the optical imaging systems 210, 220 and 230 of the second embodiment are shown, which represent the distortion size values corresponding to different image heights. Figure 9D The magnification chromatic aberration curves of the optical imaging systems 210, 220 and 230 of the second embodiment are shown, which represent the deviation of different image heights on the imaging surface after the light rays pass through the system. According to the formula Figures 9A to 9D It can be seen that the optical imaging systems 210, 220 and 230 of the second embodiment can achieve good imaging quality.

[0091] Third embodiment

[0092] The optical imaging system according to the third embodiment of the present application is described below with reference to Figures 10 to 13D The optical imaging system according to the third embodiment of the present application is described below with reference to Figure 10 ​​​​​​​​​​A structural schematic diagram of the optical imaging system 310 according to Embodiment 1 of the third embodiment of the present application is shown; Figure 11 A structural schematic diagram of the optical imaging system 320 according to Embodiment 2 of the third embodiment of the present application is shown; Figure 12 A structural schematic diagram of the optical imaging system 330 according to Embodiment 3 of the third embodiment of the present application is shown.

[0093] As shown in Figures 10 to 12 The optical imaging systems 310, 320, and 330 each include a lens barrel and an eight-piece lens group and a spacer group disposed in the lens barrel. The eight-piece lens group includes, in order from the object side to the image side, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, and an eighth lens E8. A stop STO can be disposed between the object side and the first lens E1. The spacer group includes a first spacer P1, a second spacer P2, a third spacer P3, a fourth spacer P4, a fifth spacer P5, a sixth spacer P6, and a seventh spacer P7. The spacers can block extraneous light rays during imaging from entering the next lens, so that the lens and the lens barrel P0 are better supported, and the structural stability of the optical imaging system is enhanced.

[0094] The first lens E1 has positive refractive power, with a convex object side surface S1 and a concave image side surface S2. The second lens E2 has negative refractive power, with a convex object side surface S3 and a concave image side surface S4. The third lens E3 has negative refractive power, with a convex object side surface S5 and a concave image side surface S6. The fourth lens E4 has positive refractive power, with a convex object side surface S7 and a convex image side surface S8. The fifth lens E5 has negative refractive power, with a convex object side surface S9 and a concave image side surface S10. The sixth lens E6 has negative refractive power, with a concave object side surface S11 and a convex image side surface S12. The seventh lens E7 has positive refractive power, with a convex object side surface S13 and a convex image side surface S14. The eighth lens E8 has negative refractive power, with a convex object side surface S15 and a concave image side surface S16. The filter has an object side surface S17 (not shown) and an image side surface S18 (not shown). Light from the object passes through the surfaces S1 to S18 in order and is ultimately imaged on an imaging surface S19 (not shown).

[0095] Table 5 shows a table of basic parameters of the optical imaging system of the third embodiment, where the units of the radius of curvature, the thickness / distance, and the focal length are millimeters (mm).

[0096]

[0097] Table 5

[0098] In the embodiment, the total effective focal length f of the optical imaging system is 8.58 mm, the value of the half of the maximum field of view angle Semi-FOV of the optical imaging system is 36.39°, the value of the entrance pupil diameter EPD of the optical imaging system is 4.88 mm, and the value of the combined focal length f78 of the seventh lens and the eighth lens is 17.79 mm.

[0099] In the third embodiment, the object side and the image side of any one of the first lens E1 to the eighth lens E8 are aspherical surfaces. Table 6 gives the high-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28, A30, A32, A34, A36, A38, A40, A42, A44, A46, A48, A50, A52, A54, A56, A58, A60, A62, A64, A66, A68, A70, A72, A74, A76, A78, A80, A82, A84, A86, A88, A90, A92, A94, A96, A98, A100, A102, A104, A106, A108, A110, A112, A114, A116, A118, A120, A122, A124, A126, A128, A130, A132, A134, A136, A138, A140, A142, A144, A146, A148, A150, A152, A154, A156, A158, A160, A162, A164, A166, A168, A170, A172, A174, A176, A178, A180, A182, A184, A186, A188, A190, A192, A194, A196, A198, A200, A202, A204, A206, A208, A210, A212, A214, A216, A218, A220, A222, A224, A226, A228, A230, A232, A234, A236, A238, A240, A242, A244, A246, A248, A250, A252, A254, A256, A258, A260, A262, A264, A266, A268, A270, A272, A274, A276, A278, A280, A282, A284, A286, A288, A290, A292, A294, A296, A298, A300, A302, A304, A306, A308, A310, A312, A314, A316, A318, A320, A322, A324, A326, A328, A330, A332, A334, A336, A338, A340, A342, A344, A346, A348, A350, A352, A354, A356, A358, A360, A362, A364, A366, A368, A370, A372, A374, A376, A378, A380, A382, A384, A386, A388, A390, A392, A394, A396, A398, A400, A402, A404, A406, A408, A410, A412, A414, A416, A418, A420, A422, A424, A426, A428, A430, A432, A434, A436, A438, A440, A442, A444, A446, A448, A450, A452, A454, A456, A458, A460, A462, A464, A466, A468, A470, A472, A474, A476, A478, A480, A482, A484, A486, A488, A490, A492, A494, A496, A498, A500, A502, A504, A506, A508, A510, A512, A514, A516 of the aspherical surfaces S1-S16 that can be used in the third embodiment. 10 12 14 16 18 20 22 24 26 28 30 .

[0100]

[0101]

[0102] Table 6

[0103] Figure 13A The on-axis chromatic aberration curves of the optical imaging systems 310, 320 and 330 of the third embodiment are shown, which represent the convergence focus deviation of light rays of different wavelengths after passing through the optical imaging systems 310, 320 and 330. Figure 13B The astigmatism curves of the optical imaging systems 310, 320 and 330 of the third embodiment are shown, which represent the meridional image surface curvature and sagittal image surface curvature corresponding to different image heights. Figure 13C The distortion curves of the optical imaging systems 310, 320 and 330 of the third embodiment are shown, which represent the distortion size values corresponding to different image heights. Figure 13D The magnification chromatic aberration curves of the optical imaging systems 310, 320 and 330 of the third embodiment are shown, which represent the deviation of different image heights on the imaging surface after the light rays pass through the system. According to the Figures 13A to 13D It can be seen that the optical imaging systems 310, 320 and 330 of the third embodiment can achieve good imaging quality.

[0104] ​​​​​​​​​​Table 7 gives some basic parameters of the barrel, the spacer, such as dls, dlm, Dlm, d2s, D2s, d3s, D3m, d4m, d5s, D5s, d6m, D6m, d7m, D7m, d0m, EP01, CP1, EP12, EP23, EP34, EP56, EP67, and CP7, etc. of each embodiment in the first embodiment to the third embodiment. The basic parameters listed in Table 7 are measured according to the labeling method shown in Table 7, and the units of the basic parameters listed in Table 7 are all millimeters (mm). Figure 1

[0105]

[0106]

[0107] Table 7

[0108] In summary, the conditional expressions of each embodiment in the first embodiment to the third embodiment satisfy the relationships shown in Table 8.

[0109]

[0110]

[0111] Table 8

[0112] The present application also provides an imaging device, the electronic photosensitive element of which can be a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The imaging device can be a stand-alone imaging apparatus such as a digital camera, or an imaging module integrated on a mobile electronic device such as a mobile phone. The imaging device is equipped with the optical imaging system described above.

[0113] The above description is merely preferred embodiments of the present application and a description of the principles of the technology used. Those skilled in the art should understand that the scope of the application involved in the present application is not limited to the technical solutions formed by the specific combinations of the technical features described above, and should also cover other technical solutions formed by any combinations of the technical features described above or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by the mutual replacement of the above-described features and the technical features disclosed in the present application (but not limited to) having similar functions.​

Claims

1. An optical imaging system, characterized by, Comprising: an eight-piece lens group comprising, in order from an object side to an image side along an optical axis: a first lens having positive refractive power, an object side surface of which is convex, and an image side surface of which is concave; a second lens having negative refractive power, an object side surface of which is convex, and an image side surface of which is concave; a third lens having negative refractive power, an object side surface of which is convex, and an image side surface of which is concave; a fourth lens having positive refractive power, an object side surface of which is convex, and an image side surface of which is convex; a fifth lens having negative refractive power; a sixth lens having negative refractive power, an object side surface of which is concave, and an image side surface of which is convex; a seventh lens having positive refractive power, an object side surface of which is convex; an eighth lens having negative refractive power, an object side surface of which is convex, and an image side surface of which is concave; a spacer group comprising a fifth spacer abutting against an image side surface of the fifth lens, a sixth spacer abutting against an image side surface of the sixth lens, and a seventh spacer abutting against an image side surface of the seventh lens; and a lens barrel in which the eight-piece lens group and the spacer group are disposed, wherein the number of lenses having refractive power in the optical imaging system is eight; an effective focal length f5 of the fifth lens, a separation EP56 of the fifth spacer and the sixth spacer along the optical axis, and an air separation T67 of the sixth lens and the seventh lens on the optical axis satisfy: -76.19 ≤ f5 / (EP56+T67) ≤ -34.79, an effective focal length f8 of the eighth lens, a separation EP67 of the sixth spacer and the seventh spacer along the optical axis, and an air separation T78 of the seventh lens and the eighth lens on the optical axis satisfy: -10.60 ≤ f8 / (EP67+T78) ≤ -6.75, and a combined focal length f78 of the seventh lens and the eighth lens, an air separation T78 of the seventh lens and the eighth lens on the optical axis, a central thickness CT8 of the eighth lens on the optical axis, and a maximum thickness CP7 of the seventh spacer satisfy: 14.77 ≤ f78 / (CP7+T78+CT8) ≤ 31.

08.

2. The optical imaging system of claim 1, wherein, the spacer group further comprises a second spacer abutting against an image side surface of the second lens, wherein an effective focal length f2 of the second lens, an inner diameter d2s of an object side surface of the second spacer, and an outer diameter D2s of the object side surface of the second spacer satisfy: -17.28 ≤ f2 / (D2s-d2s) ≤ -4.68, and an effective focal length f3 of the third lens, the inner diameter d2s of the object side surface of the second spacer, and the outer diameter D2s of the object side surface of the second spacer satisfy: -88.58 ≤ f3 / (D2s+d2s) ≤ -18.

50.

3. The optical imaging system of claim 1 or 2, wherein the spacer group further comprises a third spacer abutting against an image side surface of the third lens, and a fourth spacer abutting against an image side surface of the fourth lens, The radius of curvature R7 of the object side surface of the fourth lens, the radius of curvature R8 of the image side surface of the fourth lens, the inner diameter d3s of the object side surface of the third spacer, and the interval EP34 of the third spacer and the fourth spacer along the optical axis satisfy: -39.26≤d3s / R7+R8 / EP34≤-20.

05.

4. The optical imaging system of claim 1 or 2, wherein, The spacer set further comprises a third spacer abutting against the image side surface of the third lens and a fourth spacer abutting against the image side surface of the fourth lens, The effective focal length f4 of the fourth lens, the air interval T34 of the third lens and the fourth lens along the optical axis, the outer diameter D3m of the image side surface of the third spacer, and the inner diameter d4m of the image side surface of the fourth spacer satisfy: 85<(f4 / d4m)×(D3m / T34)≤163.66, or (f4 / d4m)×(D3m / T34)=69.24, or (f4 / d4m)×(D3m / T34)=53.

36.

5. The optical imaging system of claim 1 or 2, wherein, The effective focal length f6 of the sixth lens, the effective focal length f7 of the seventh lens, the inner diameter d6m of the image side surface of the sixth spacer, and the outer diameter D6m of the image side surface of the sixth spacer satisfy: -18<(f6+f7) / (D6m-d6m)≤-5.

27.

6. The optical imaging system of claim 1 or 2, wherein, The inner diameter d0m of the image side end surface of the lens barrel, the total effective focal length f of the optical imaging system, and half of the maximum field angle Semi-FOV of the optical imaging system satisfy: 1.65≤d0m / (f×tan(Semi-FOV))≤1.

85.

7. The optical imaging system of claim 2, wherein, The spacer set further comprises a first spacer abutting against the image side surface of the first lens and a third spacer abutting against the image side surface of the third lens, wherein a minimum value minVa of Abbe numbers of all the lenses among the first to third lenses, a separation EP12 of the first spacer and the second spacer along the optical axis, and a separation EP23 of the second spacer and the third spacer along the optical axis satisfy: 16.93 mm < minVa / (EP12+EP23) < 19.18 mm -1 . -1 and a minimum value minVb of Abbe numbers of all the lenses in the sixth to eighth lenses, a separation EP67 of the sixth spacer and the seventh spacer along the optical axis, and an air separation T78 of the seventh lens and the eighth lens on the optical axis satisfy: 23.34 mm -1 ≤ minVb / (EP67+T78) ≤ 37.43 mm -1 .

8. The optical imaging system of claim 2, wherein, The spacer set further comprises a first spacer abutting against the image side surface of the first lens, a second spacer abutting against the image side surface of the second lens, and a third spacer abutting against the image side surface of the third lens, The effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens, the inner diameter d1s of the object side surface of the first spacer, the inner diameter d2s of the object side surface of the second spacer, and the inner diameter d3s of the object side surface of the third spacer satisfy: |f1 / d1s|<|f2 / d2s|<|f3 / d3s|.

9. The optical imaging system of claim 1 or 2, wherein, The radius of curvature R9 of the object side surface of the fifth lens, the radius of curvature R10 of the image side surface of the fifth lens, and the outer diameter D5s of the object side surface of the fifth spacer satisfy: 2<(R9-R10) / D5s≤8.40, and the radius of curvature R11 of the object side surface of the sixth lens, the radius of curvature R12 of the image side surface of the sixth lens, and the inner diameter d5s of the object side surface of the fifth spacer satisfy: -1.49≤(R11+R12) / d5s≤-1.

38.

10. The optical imaging system of claim 1 or 2, wherein, The inner diameter d7m of the image side surface of the seventh spacer, the outer diameter D7m of the image side surface of the seventh spacer, the curvature radius R15 of the object side surface of the eighth lens, and the curvature radius R16 of the image side surface of the eighth lens satisfy: 15.30≤(D7m+d7m) / (R15-R16)≤19.

95.

11. The optical imaging system of claim 1 or 2, wherein, The spacer set further includes a first spacer abutting against the image side surface of the first lens, wherein the curvature radius R1 of the object side surface of the first lens, the curvature radius R3 of the object side surface of the second lens, the inner diameter d1m of the image side surface of the first spacer, and the outer diameter D1m of the image side surface of the first spacer satisfy: 0.76≤(D1m×R1) / (R3×d1m)<1.

12. The optical imaging system of claim 1 or 2, wherein, The spacer set further includes a first spacer abutting against the image side surface of the first lens, wherein the effective focal length f1 of the first lens, the entrance pupil diameter EPD of the optical imaging system, and the interval EP01 of the object side end surface of the lens barrel and the first spacer along the optical axis satisfy: 24.60mm≤f1 / EP01×EPD<38mm.

13. The optical imaging system of claim 2, wherein, The spacer set further includes a first spacer abutting against the image side surface of the first lens, wherein the curvature radius R2 of the image side surface of the first lens, the air interval T12 of the first lens and the second lens on the optical axis, and the maximum thickness CP1 of the first spacer satisfy: 86.30≤R2 / (CP1+T12)≤105.85, and the curvature radius R4 of the image side surface of the second lens, the central thickness CT2 of the second lens on the optical axis, and the interval EP12 of the first spacer and the second spacer along the optical axis satisfy: 3.25≤R4 / (EP12+CT2)≤3.94.

Images