Imaging system

Abstract

The application discloses an imaging system, comprising a lens group and a plurality of spacer elements, the lens group is composed of 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 from the object side to the image side along the optical axis, wherein the first lens has positive refractive power, the second lens has negative refractive power, the seventh lens has positive refractive power, and the eighth lens has negative refractive power; and the imaging system satisfies: 5<(D0s-d2s) / (d0s-d2s)*(EPD / T78)<20, wherein D0s is the outer diameter of the object side end of the lens barrel, d0s is the inner diameter of the object side end of the lens barrel, d2s is the inner diameter of the object side surface of the second spacer element, EPD is the entrance pupil diameter of the lens group, and T78 is the air gap of the seventh lens and the eighth lens along the optical axis.

Description

[0001] Divisional application statement

[0002] This application is a divisional application of Chinese invention patent application filed on October 24, 2022, entitled "Imaging System" and with application number 202211307287.3. Technical Field

[0003] This application relates to the field of optical components, and more specifically, to an imaging system. Background Technology

[0004] In recent years, with the widespread use of mobile phones in daily life, people have not only demanded higher and higher image quality from mobile phone lenses, but also paid more and more attention to the appearance of the lenses. As a result, large-aperture mobile phone lenses have gradually become the development trend of the industry.

[0005] Mobile phone lenses typically include spacers for coupling adjacent lenses. For lenses with five or more elements, the large differences in lens spacing often cause assembly stability issues. For large image sensor lenses, as the imaging area increases, stray light easily appears at the lens edges. These stray light and assembly stability problems severely affect the lens's image quality. Therefore, how to rationally set the lens's optical parameters and the structure and size of the lenses and spacers to improve stray light and optimize the lens's assembly stability is a pressing problem in this field.

[0006] It should be understood that the background section is intended to provide some useful background for understanding the technology; however, this content is not necessarily what was known or understood by a person skilled in the art prior to the filing date of this application. Summary of the Invention

[0007] This application provides an imaging system comprising a lens group and a plurality of spacer elements. The lens group consists of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially along the optical axis from the object side to the image side. The first lens has positive optical power, the second lens has negative optical power, the seventh lens has positive optical power, and the eighth lens has negative optical power. The plurality of spacer elements include: a second spacer element disposed on the image side of the second lens and in contact with the image side surface of the second lens; a third spacer element disposed on the image side of the third lens and in contact with the image side surface of the third lens; a fourth spacer element disposed on the image side of the fourth lens and in contact with the image side surface of the fourth lens; a fifth spacer element disposed on the image side of the fifth lens and in contact with the image side surface of the fifth lens; a sixth spacer element disposed on the image side of the sixth lens and in contact with the image side surface of the sixth lens; and a seventh spacer element disposed on the image side of the seventh lens and in contact with the image side surface of the seventh lens. The imaging system satisfies: 3mm. 2 <f / TAN(Semi-FOV)*(d6s-D2m)<27mm 2 Where f is the total effective focal length of the lens group, Semi-FOV is half of the maximum field of view of the lens group, D2m is the outer diameter of the image side of the second spacer element, and d6s is the inner diameter of the object side of the sixth spacer element.

[0008] This application also provides an imaging system comprising a lens group, a plurality of spacers, and a lens barrel for accommodating the lens group and the plurality of spacers. The lens group consists of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially along the optical axis from the object side to the image side. The first lens has positive optical power, the second lens has negative optical power, the seventh lens has positive optical power, and the eighth lens has negative optical power. The plurality of spacers includes: a second spacer disposed on the image side of the second lens and in contact with the image side surface of the second lens; a sixth spacer disposed on the image side of the sixth lens and in contact with the image side surface of the sixth lens; and a seventh spacer disposed on the image side of the seventh lens and in contact with the image side surface of the seventh lens. The imaging system satisfies: 5 < (D0s - d2s) / (d0s - d2s) * (EPD / T78) < 20, where D0s is the outer diameter of the object-side end of the lens barrel, d0s is the inner diameter of the object-side end of the lens barrel, d2s is the inner diameter of the object-side surface of the second spacer element, EPD is the entrance pupil diameter of the lens group, and T78 is the air gap between the seventh lens and the eighth lens along the optical axis.

[0009] In an embodiment of the present application, the imaging system satisfies: R11 / R12 > 1, and -40 mm 2 <f8*(D7s - D5s) < -15 mm 2 ; where, R11 is the radius of curvature of the object side surface of the sixth lens, R12 is the radius of curvature of the image side surface of the sixth lens, f8 is the effective focal length of the eighth lens, D5s is the outer diameter of the object side surface of the fifth spacer element, and D7s is the outer diameter of the object side surface of the seventh spacer element.

[0010] In an embodiment of the present application, the imaging system satisfies: -15 mm 2 <(EP67 + EP34)*R15 < 0 mm 2 , where, EP34 is the distance along the optical axis from the image side surface of the third spacer element to the object side surface of the fourth spacer element, EP67 is the distance along the optical axis from the image side surface of the sixth spacer element to the object side surface of the seventh spacer element, and R15 is the radius of curvature of the object side surface of the eighth lens.

[0011] In an embodiment of the present application, the imaging system satisfies: 0.8 mm < D2s / (N2 - N1) / 10 < 15 mm, where, D2s is the outer diameter of the object side surface of the second spacer element, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0012] In an embodiment of the present application, the imaging system satisfies: 5 < (f*T67) / (T56*EP67) < 21, where, f is the total effective focal length of the imaging system, T56 is the air gap along the optical axis between the fifth lens and the sixth lens, T67 is the air gap along the optical axis between the sixth lens and the seventh lens, and EP67 is the distance along the optical axis from the image side surface of the sixth spacer element to the object side surface of the seventh spacer element. [[ID=set18]]

[0013] In an embodiment of the present application, the imaging system satisfies: 2 < D4s / D3s + f1 / R1 < 6, where, f1 is the effective focal length of the first lens, R1 is the radius of curvature of the object side surface of the first lens, D3s is the outer diameter of the object side surface of the third spacer element, and D4s is the outer diameter of the object side surface of the fourth spacer element.

[0014] In an embodiment of the present application, the imaging system satisfies: -4 mm 2 <CP3*f2 + CP4*f6 ≤ -0.28 mm 2Wherein, CP3 is the maximum thickness of the third spacer element, CP4 is the maximum thickness of the fourth spacer element, f2 is the effective focal length of the second lens, and f6 is the effective focal length of the sixth lens.

[0015] In one embodiment of this application, at least one of the object-side surface and the image-side surface of at least one of the first lens to the eighth lens is aspherical, and at least one of the object-side surface and the image-side surface of at least one of the first lens to the eighth lens has at least one inflection point, wherein the absolute value of the effective focal length of the eighth lens is less than the absolute value of the effective focal length of any one of the first lens to the seventh lens.

[0016] In one embodiment of this application, the imaging system satisfies: Ri / R(i+1)>0, and Ri>0, i=1, 2, 3, 4 or 5, where, when i is 1, Ri represents the radius of curvature of the object-side surface of the first lens, and R(i+1) represents the radius of curvature of the image-side surface of the first lens; when i is 2, Ri represents the radius of curvature of the image-side surface of the first lens, and R(i+1) represents the radius of curvature of the object-side surface of the second lens; when i is 3, Ri represents the radius of curvature of the object-side surface of the second lens, and R(i+1) represents the radius of curvature of the image-side surface of the second lens; when i is 4, Ri represents the radius of curvature of the image-side surface of the second lens, and R(i+1) represents the radius of curvature of the object-side surface of the third lens; when i is 5, Ri represents the radius of curvature of the object-side surface of the third lens, and R(i+1) represents the radius of curvature of the image-side surface of the third lens.

[0017] In one embodiment of this application, the imaging system satisfies: 1mm < (V1-V4)*EP56 < 28mm, where V1 is the Abbe number of the first lens, V4 is the Abbe number of the fourth lens, and EP56 is the distance along the optical axis from the image side of the fifth spacer element to the object side of the sixth spacer element.

[0018] In one embodiment of this application, the imaging system satisfies: 5mm 2 <D3m*CT1+D4m*EP23<12mm 2 Wherein, D3m is the outer diameter of the image side of the third spacer element, D4m is the outer diameter of the image side of the fourth spacer element, CT1 is the center thickness of the first lens, and EP23 is the distance along the optical axis from the image side of the second spacer element to the object side of the third spacer element.

[0019] In one embodiment of this application, the imaging system satisfies: 7mm 2 <(D6m-D5m)*d5m<29mm 2, where D5m is the outer diameter of the image side of the fifth spacer element, D6m is the outer diameter of the image side of the sixth spacer element, and d5m is the inner diameter of the image side of the fifth spacer element.

[0020] This application provides an imaging system including an eight-piece lens group. By reasonably configuring the optical powers of the first lens, the second lens, the seventh lens, and the eighth lens, a positive and a negative lens combination is provided at both the front end and the rear end of the lens group, enabling the lens to be thin and light while ensuring good processing feasibility. On this basis, stray light is eliminated as much as possible by reasonably arranging spacer elements between the lenses, so that the imaging system can have high imaging quality. Further, based on the above settings of the optical power, surface shape, and spacer elements, by reasonably controlling the relationship between the total effective focal length and the maximum field angle of the system and the outer diameter of the image side of the second spacer element and the inner diameter of the object side of the sixth spacer element, the step difference between the second lens and the fifth lens can be advantageously controlled while reasonably controlling the size of the imaging surface; with 3 < f / TAN(Semi-FOV)*(d6s - D2m) < 27, not only can the lens be made thin and light by controlling the total effective focal length f of the lens group and half of the maximum field angle of the lens group Semi-FOV, but also the problems such as poor imaging quality and failure of the lens caused by large changes in the air gap after the drop test of the large image surface lens can be effectively improved by controlling the outer diameter D2m of the image side of the second spacer element and the inner diameter d6s of the object side of the sixth spacer element, enhancing the reliability and quality of the lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features, objects, and advantages of this application will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings:

[0022] Figure 1 shows a schematic diagram of parameter markings of the imaging system according to this application;

[0023] Figure 2 shows a schematic cross-sectional view of an imaging system according to Embodiment 1 of this application;

[0024] Figure 3 shows another schematic cross-sectional view of an imaging system according to Embodiment 1 of this application;

[0025] Figure 4 shows yet another schematic cross-sectional view of an imaging system according to Embodiment 1 of this application;

[0026] <​​​Figure 6 A cross-sectional schematic diagram of an imaging system according to Embodiment 2 of this application is shown;

[0028] Figure 7 A cross-sectional schematic diagram of another imaging system according to Embodiment 2 of this application is shown;

[0029] Figure 8 A cross-sectional schematic diagram of another imaging system according to Embodiment 2 of this application is shown;

[0030] Figures 9A to 9D The on-axis chromatic aberration curve, astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging system according to Embodiment 2 of this application are shown respectively.

[0031] Figure 10 A cross-sectional schematic diagram of an imaging system according to Embodiment 3 of this application is shown;

[0032] Figure 11 A cross-sectional schematic diagram of another imaging system according to Embodiment 3 of this application is shown;

[0033] Figure 12 A cross-sectional schematic diagram of another imaging system according to Embodiment 3 of this application is shown; and

[0034] Figures 13A to 13D The on-axis chromatic aberration curve, astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging system according to Embodiment 3 of this application are shown respectively. Detailed Implementation

[0035] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0036] 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.

[0037] 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 strictly to scale.

[0038] In this article, curvature or paraxial curvature refers to the curvature of the region near the optical axis. If the curvature of a lens surface is positive and its location is not defined, it means that the curvature of the lens surface is positive at least in the paraxial region; if the curvature of a lens surface is negative and its location is not defined, it means that the curvature of the lens surface is negative at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane is called the image-side surface of the lens.

[0039] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0040] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized sense, unless expressly so specified herein.

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other. The following embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. For example, the lens groups (i.e., the first lens to the eighth lens), lens barrel structure, and spacer elements in the various embodiments of this application can be arbitrarily combined, and it is not limited to the lens group in one embodiment being only combined with the lens barrel structure, spacer elements, etc. of that embodiment.

[0042] The features, principles and other aspects of this application are described in detail below.

[0043] An imaging system according to an exemplary embodiment of this application includes a lens group, a plurality of spacer elements, and a lens barrel for accommodating the lens group and the plurality of spacer elements, wherein the lens group includes, in sequence along the optical axis from the object side to the image side, 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.

[0044] In an exemplary embodiment, the first and seventh lenses can have positive optical power, while the second and eighth lenses can have negative optical power. This optical power setting facilitates lens thinning. In some examples, the third lens can have positive optical power, the sixth lens can have negative optical power, and the signs of the optical power of the fourth and fifth lenses can differ; for example, when the fourth lens has positive optical power, the fifth lens can have negative optical power, and vice versa. By rationally allocating the optical power of each lens in the lens group, the imaging effect can be effectively improved.

[0045] In an exemplary embodiment, the plurality of spacer elements may include a second spacer element located between the second lens and the third lens and in contact with the image-side surface of the second lens, a third spacer element located between the third lens and the fourth lens and in contact with the image-side surface of the third lens, a fourth spacer element located between the fourth lens and the fifth lens and in contact with the image-side surface of the fourth lens, a fifth spacer element located between the fifth lens and the sixth lens and in contact with the image-side surface of the fifth lens, a sixth spacer element located between the sixth lens and the seventh lens and in contact with the image-side surface of the sixth lens, and a seventh spacer element located between the seventh lens and the eighth lens and in contact with the image-side surface of the seventh lens.

[0046] It should be understood that this application does not specifically limit the number of spacers; any number of spacers may be included between any two lenses, and the entire imaging system may also include any number of spacers. Spacers help the imaging system intercept excess reflective light paths, reducing stray light and ghosting. Adding auxiliary support between the spacers and the lens barrel helps improve problems such as poor assembly stability and low performance yield caused by large step differences between lenses.

[0047] In an exemplary implementation, reference Figure 1 The parameter specifications indicate that the imaging system meets the following requirements: 3mm 2 <f / TAN(Semi-FOV)*(d6s-D2m)<27mm 2 Where f is the total effective focal length of the lens group, Semi-FOV is half of the maximum field of view of the lens group, D2m is the outer diameter of the image-side surface of the second spacer element P2, and d6s is the inner diameter of the object-side surface of the sixth spacer element P6. Furthermore, the imaging system satisfies: 5mm 2<f / TAN(Semi-FOV)*(d6s - D2m)<25mm 2 Satisfying the above conditional expression, while effectively controlling the size of the imaging surface, the step difference between the second lens E2 and the fifth lens E5 can also be controlled, so that the imaging system has better assembly stability, effectively solving problems such as large changes in the air gap after the drop test of the large image surface lens, resulting in poor lens imaging quality and failure, improving the lens reliability, and enhancing the quality of the large image surface lens.

[0048] It should be understood that, in order to make the structure and markings of the attached drawings clearer, Figure 1 only the parameter markings of the structures of some lenses and some spacer elements are taken as examples. For the size limitations of the similar structures of the remaining lenses and the remaining spacer elements, reference can be made to the relevant dimension structures and markings that have been marked above, and this application will not elaborate here.

[0049] In an exemplary embodiment, referring to Figure 1 the parameter markings, the imaging system satisfies: R11 / R12 > 1, and -40mm 2 <f8*(D7s - D5s)< -15mm 2 ; where, R11 is the radius of curvature of the object side surface of the sixth lens E6, R12 is the radius of curvature of the image side surface of the sixth lens E6, f8 is the effective focal length of the eighth lens E8, D5s is the outer diameter of the object side surface of the fifth spacer element P5, and D7s is the outer diameter of the object side surface of the seventh spacer element P7. Further, the imaging system satisfies: 1 < R11 / R12 < 2, and -36mm 2 <f8*(D7s - D5s)< -18mm 2 By controlling the ratio of the radius of curvature of the object side surface and the image side surface of the sixth lens E6, it is beneficial to the diversification of the structural design of the sixth lens E6 and the reasonable selection of the sixth spacer element P6, so that the large image surface lens has a large improvement space, which plays an important role in enhancing the quality of the large image surface lens; in addition, by controlling the product of the effective focal length of the eighth lens E8 and the difference between the outer diameter of the object side surface of the seventh spacer element P7 and the outer diameter of the object side surface of the fifth spacer element P5, the step difference between the sixth lens E6 and the seventh lens E7 can be effectively controlled to be within a better range, thereby effectively enhancing the quality of the imaging system.

[0050] In an exemplary embodiment, referring to Figure 1 the parameter markings, the imaging system satisfies: -15mm 2 <(EP67 + EP34)*R15 < 0mm 2, where EP34 is the distance along the optical axis from the image side of the third spacer element P3 to the object side of the fourth spacer element P4, EP67 is the distance along the optical axis from the image side of the sixth spacer element P6 to the object side of the seventh spacer element P7, and R15 is the radius of curvature of the object side of the eighth lens E8. Further, the imaging system satisfies: -12 mm 2 <(EP67 + EP34) * R15 < -4 mm 2 . By satisfying the above conditional formula, the edge thicknesses of the fourth lens E4 and the seventh lens E7 can be effectively controlled, preventing the lens from being cracked by the assembly pressure during assembly, thereby effectively avoiding the generation of stray light caused by lens cracks and improving the imaging quality of the imaging system.

[0051] In an exemplary embodiment, referring to Figure 1 for the parameter annotation, the imaging system satisfies: 0.8 mm < D2s / (N2 - N1) / 10 < 15 mm, where D2s is the outer diameter of the object side of the second spacer element P2, N1 is the refractive index of the first lens E1, and N2 is the refractive index of the second lens E2. Further, the imaging system satisfies: 1.5 mm < D2s / (N2 - N1) / 10 < 12 mm. By satisfying the above conditional formula, the maximum field angle of the lens can be effectively guaranteed, and the non-imaging reflected light in the first lens and the second lens can be better intercepted, reducing the number and intensity of the stray light spots formed on the image plane and ensuring the quality of the large image plane lens.

[0052] In an exemplary embodiment, referring to Figure 1 for the parameter annotation, the imaging system satisfies: 5 < (f * T67) / (T56 * EP67) < 21, where f is the total effective focal length of the imaging system, T56 is the air gap along the optical axis between the fifth lens E5 and the sixth lens E6, T67 is the air gap along the optical axis between the sixth lens E6 and the seventh lens E7, and EP67 is the distance along the optical axis from the image side of the sixth spacer element P6 to the object side of the seventh spacer element P7. Further, the imaging system satisfies: 7 < (f * T67) / (T56 * EP67) < 18. By satisfying the above conditional formula, the air gap of the lens on the optical axis can be adjusted by adjusting the distance between the sixth spacer element P6 and the seventh spacer element P7, thereby effectively using the optical sensitivity to improve the offset amount and offset direction of the large image plane lens, thereby improving the performance of the imaging system; in addition, the offset amount sensitivity of the large image plane lens can be effectively reduced, and the imaging clarity and performance stability of the lens can be improved, thereby improving the product quality and performance yield.

[0053] In an exemplary embodiment, referring to Figure 1For the parameter annotation, the imaging system satisfies: 5 < (D0s - d2s) / (d0s - d2s) * (EPD / T78) < 20, where D0s is the outer diameter of the object side end of the lens barrel P0, d0s is the inner diameter of the object side end of the lens barrel P0, d2s is the inner diameter of the object side surface of the second spacer element P2, EPD is the entrance pupil diameter of the lens group, and T78 is the air gap between the seventh lens E7 and the eighth lens E8 along the optical axis. Further, the imaging system satisfies: 7 < (D0s - d2s) / (d0s - d2s) * (EPD / T78) < 18. By satisfying the above conditional formula, it is possible to effectively intercept non-imaging light from imaging on the imaging surface while ensuring the annulus width of the object side end of the large image plane lens barrel, and it is possible to improve the assembly stability of the system, reduce stray light in the system, and thus improve the imaging quality of the system on the premise of ensuring the maximum field angle of the large image plane lens.

[0054] In an exemplary embodiment, referring to Figure 1 For the parameter annotation, the imaging system satisfies: 2 < D4s / D3s + f1 / R1 < 6, where f1 is the effective focal length of the first lens E1, R1 is the curvature radius of the object side surface of the first lens E1, D3s is the outer diameter of the object side surface of the third spacer element P3, and D4s is the outer diameter of the object side surface of the fourth spacer element P4. Further, the imaging system satisfies: 2.5 < D4s / D3s + f1 / R1 < 5. By controlling this conditional formula, it is possible to ensure that the light incident angle is of a certain size, and the outer diameters of the first lens E1, the third lens E3, the fourth lens E4, and the fifth lens E5 can be maintained within a preferable range, effectively reducing the lens forming difficulty and improving the appearance quality of the system.

[0055] In an exemplary embodiment, referring to Figure 1 For the parameter annotation, the imaging system satisfies: -4mm 2 <CP3 * f2 + CP4 * f6 ≤ -0.28mm 2 , where CP3 is the maximum thickness of the third spacer element P3, CP4 is the maximum thickness of the fourth spacer element P4, f2 is the effective focal length of the second lens E2, and f6 is the effective focal length of the sixth lens E6. Further, the imaging system satisfies: -3.5mm 2 <CP3 * f2 + CP4 * f6 ≤ -0.5mm 2 . By controlling this conditional formula, it is possible to effectively control the edge thickness of the lens, making the overall lens uniformity better and reducing the lens forming difficulty; at the same time, it can effectively improve the contrast of the lens light, improve the ability of the lens to distinguish black and white lines, greatly improve the imaging clarity of the lens, and improve the imaging quality.

[0056] In an exemplary embodiment, at least one of the object-side and image-side surfaces of at least one of the first to eighth lenses is aspherical, and at least one of the object-side and image-side surfaces of at least one of the first to eighth lenses has at least one inflection point. The absolute value of the effective focal length of the eighth lens is less than the absolute value of the effective focal length of any one of the first to seventh lenses. By designing an inflection point on the object-side or image-side surface of the lens, lens performance can be improved while effectively controlling the lens edge thickness, thereby controlling the axial clearance of the inter-lens mechanism and facilitating control over the type and number of spacer elements used. Furthermore, by controlling the absolute value of the effective focal length of the eighth lens to be less than the absolute value of the effective focal length of any one of the first to seventh lenses, the imaging performance of the system can be improved, the instability during system assembly can be reduced, and the reliability of the system can be increased while controlling system cost.

[0057] In an exemplary implementation, reference Figure 1 The parameters are labeled such that the imaging system satisfies: Ri / R(i+1)>0, and Ri>0, i=1,2,3,4 or5, where i=1,R(i+1) represents the radius of curvature of the object side of the first lens and R(i+1) represents the radius of curvature of the image side of the first lens; i=2,R(i+1) represents the radius of curvature of the image side of the first lens and R(i+1) represents the radius of curvature of the object side of the second lens; i=3,R(i+1) represents the radius of curvature of the object side of the second lens and R(i+1) represents the radius of curvature of the image side of the second lens; i=4,R(i+1) represents the radius of curvature of the image side of the second lens and R(i+1) represents the radius of curvature of the object side of the third lens; i=5,R(i+1) represents the radius of curvature of the object side of the third lens and R(i+1) represents the radius of curvature of the image side of the third lens. By controlling this conditional expression, the surface shape of the object side of the first lens to the third lens can be made opposite to that of the image side, and the radius of curvature of the first lens E1 to the third lens E3 is greater than zero. This structure makes the light aperture of the first lens E1 to the third lens E3 gradually decrease, effectively reducing the energy of stray light spots generated by the reflection of light from the inner diameter surface of the second spacer element P2, and improving the imaging quality of the system.

[0058] In an exemplary implementation, reference Figure 1The imaging system is configured to satisfy the following parameters: 1mm < (V1-V4)*EP56 < 28mm, where V1 is the Abbe number of the first lens E1, V4 is the Abbe number of the fourth lens E4, and EP56 is the distance along the optical axis from the image-side surface of the fifth spacer element P5 to the object-side surface of the sixth spacer element P6. Furthermore, the imaging system satisfies: 3 < (V1-V4)*EP56 < 25. By controlling this condition, the edge thickness of the sixth lens E6 mechanism can be guaranteed, ensuring the strength and assembly stability of the sixth lens E6 as a transition lens between the first five lenses and the last two lenses. This effectively improves the Abbe numbers of the first lens E1 and the fourth lens E4, thereby enhancing the image quality of the large-image-plane lens.

[0059] In an exemplary implementation, reference Figure 1 The parameter specifications indicate that the imaging system meets the following requirements: 5mm. 2 <D3m*CT1+D4m*EP23<12mm 2 Where D3m is the outer diameter of the image-side surface of the third spacer element P3, D4m is the outer diameter of the image-side surface of the fourth spacer element P4, CT1 is the center thickness of the first lens E1, and EP23 is the distance along the optical axis from the image-side surface of the second spacer element P2 to the object-side surface of the third spacer element P3. Furthermore, the imaging system satisfies: 6mm 2 <D3m*CT1+D4m*EP23<10mm 2 Since the outer diameter of the spacer element affects the outer diameter of its adjacent lenses, the combination of its outer diameter and the center thickness of the lens affects the lens forming performance. Therefore, the outer diameter of the first lens E1 to the fifth lens E5 can be effectively controlled by controlling this conditional expression, thereby reducing the lens forming difficulty, minimizing connection line risks, and improving the system's appearance yield.

[0060] In an exemplary implementation, reference Figure 1 The parameter specifications indicate that the imaging system meets the following requirements: 7mm. 2 <(D6m-D5m)*d5m<29mm 2 Where D5m is the outer diameter of the image-side surface of the fifth spacer element P5, D6m is the outer diameter of the image-side surface of the sixth spacer element P6, and d5m is the inner diameter of the image-side surface of the fifth spacer element P5. Furthermore, the imaging system satisfies: 9 < (D6m - D5m) * d5m < 28. Since the outer diameter of the spacer element affects the outer diameter of its adjacent lens, and its inner diameter can intercept unnecessary reflected light within the system, but when the inner diameter of the spacer element is smaller than the outer diameter of the principal ray, it will affect the luminous flux. Therefore, by controlling this conditional expression, while ensuring that the main parameters of the system remain unchanged, the assembly stability of the system can be improved, the imaging of unnecessary reflected light on the imaging surface can be reduced, system stray light and performance yield can be improved, and imaging quality can be enhanced.

[0061] In exemplary embodiments, the imaging system may further include a filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface. The imaging system according to the above embodiments of this application may employ multiple lenses, such as the eight lenses mentioned above. By rationally allocating the optical power, surface shape, center thickness of each lens, and distance between each lens along the optical axis, incident light can be effectively converged, the overall optical length of the imaging system can be reduced, and the manufacturability of the imaging system can be improved, making the imaging system more conducive to manufacturing.

[0062] In embodiments of this application, at least one of the mirror surfaces of each lens is an aspherical mirror surface; that is, at least one mirror surface from the object-side surface of the first lens to the image-side surface of the sixth lens is an aspherical mirror surface. The characteristic of an aspherical lens is that its curvature changes continuously from the lens center to the lens periphery. Unlike a spherical lens, which has a constant curvature from the lens center to the lens periphery, an aspherical lens has better radius of curvature characteristics, offering advantages in improving distortion aberrations and astigmatism. Using an aspherical lens can eliminate aberrations that occur during imaging as much as possible, thereby improving image quality. Furthermore, aspherical lenses have a large effective diameter degree of freedom, allowing for arbitrary design of their surface shape to improve system performance. Optionally, the object-side surface and image-side surface of each of the first, second, third, fourth, fifth, sixth, seventh, and eighth lenses are both aspherical mirror surfaces.

[0063] Specific embodiments of the imaging system applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

[0064] Example 1

[0065] The following is for reference Figures 2 to 5D An imaging system according to Embodiment 1 of this application is described. Figures 2 to 4 Cross-sectional schematic diagrams of three imaging systems according to Embodiment 1 of this application are shown respectively.

[0066] like Figures 2 to 4 As shown, imaging systems 110, 120, and 130 each include a lens barrel P0, lens groups E1 to E8, and multiple spacer elements P2 to P7. In some cases, imaging systems 110, 120, and 130 may include the same lens groups E1 to E8. Specifically, the lens groups, from the object side to the image side, sequentially include: 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.

[0067] In some examples, the first lens E1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens E2 has negative optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens E3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being concave. The fourth lens E4 has positive optical power, with its object-side surface S7 being concave and its image-side surface S8 being convex. The fifth lens E5 has negative optical power, with its object-side surface S9 being concave and its image-side surface S10 being convex. The sixth lens E6 has negative optical power, with its object-side surface S11 being convex and its image-side surface S12 being concave. The seventh lens E7 has positive optical power, with its object-side surface S13 being convex and its image-side surface S14 being convex. The eighth lens E8 has negative optical power, with its object-side surface S15 being concave and its image-side surface S16 being concave. The filter (not shown) has an object-side surface S17 and an image-side surface S18. Light from the object passes sequentially through the surfaces S1 to S18 and is finally imaged onto the imaging surface (not shown).

[0068] Table 1 shows the basic parameters of the imaging system of Example 1, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm).

[0069]

[0070] Table 1

[0071] In this embodiment, the total effective focal length f of the lens group is 7.55 mm, half of the maximum field of view (Semi-FOV) of the lens group is 47.4°, and the entrance pupil diameter (EPD) of the lens group is 4.00 mm.

[0072] In this embodiment, the surface shape x of the aspherical surfaces included in the object-side and image-side surfaces of the lenses from the first lens E1 to the eighth lens E8 can be defined using, but is not limited to, the following aspherical formula:

[0073]

[0074] 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 below gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28 and A30 that can be used for each of the aspherical mirrors S1 to S16 in Example 1.

[0075]

[0076]

[0077] Table 2

[0078] Figure 5A The on-axis chromatic aberration curve of the imaging system of Embodiment 1 is shown, which represents the deviation of the convergence focal point of light of different wavelengths after passing through the imaging lens. Figure 5B The astigmatism curves of the imaging system of Example 1 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 5C The distortion curves of the imaging system of Example 1 are shown, which represent the distortion magnitude values ​​corresponding to different image heights. Figure 5D The magnification chromatic aberration curve of the imaging system of Embodiment 1 is shown, which represents the deviation of different image heights on the imaging plane after light passes through the system. According to Figures 5A to 5D It can be seen that the imaging system given in Example 1 can achieve good imaging quality.

[0079] like Figures 2 to 4 As shown, the imaging systems 110, 120, and 130 each include a second spacer element P2, a third spacer element P3, a fourth spacer element P4, a fifth spacer element P5, a sixth spacer element P6, and a seventh spacer element P7. Specifically, the second spacer element P2 is disposed between the second lens E2 and the third lens E3 and contacts the image-side surface of the second lens E2; the third spacer element P3 is disposed between the third lens E3 and the fourth lens E4 and contacts the image-side surface of the third lens E3; the fourth spacer element P4 is disposed between the fourth lens E4 and the fifth lens E5 and contacts the image-side surface of the fourth lens E4; the fifth spacer element P5 is disposed between the fifth lens E5 and the sixth lens E6 and contacts the image-side surface of the fifth lens E5; the sixth spacer element P6 is disposed between the sixth lens E6 and the seventh lens E7 and contacts the image-side surface of the sixth lens E6; and the seventh spacer element P7 is disposed between the seventh lens E7 and the eighth lens E8 and contacts the image-side surface of the seventh lens E7. The aforementioned multiple spacer elements can block excess external light from entering, allowing the lens to better support the lens barrel and enhancing the structural stability of imaging systems 110, 120, and 130.

[0080] Example 2

[0081] The following is for reference Figures 6 to 9D An imaging system according to Embodiment 2 of this application is described. Figures 6 to 8 Cross-sectional schematic diagrams of three imaging systems according to Embodiment 2 of this application are shown respectively.

[0082] like Figures 6 to 8As shown, imaging systems 210, 220, and 230 each include a lens barrel P0, lens groups E1 to E8, and multiple spacer elements P2 to P7. In some cases, imaging systems 210, 220, and 230 may include the same lens groups E1 to E8. Specifically, the lens groups, from the object side to the image side, sequentially include: 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.

[0083] In some examples, the first lens E1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens E2 has negative optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens E3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being concave. The fourth lens E4 has negative optical power, with its object-side surface S7 being concave and its image-side surface S8 being convex. The fifth lens E5 has positive optical power, with its object-side surface S9 being convex and its image-side surface S10 being concave. The sixth lens E6 has negative optical power, with its object-side surface S11 being convex and its image-side surface S12 being concave. The seventh lens E7 has positive optical power, with its object-side surface S13 being convex and its image-side surface S14 being convex. The eighth lens E8 has negative optical power, with its object-side surface S15 being concave and its image-side surface S16 being concave. The filter (not shown) has an object-side surface S17 and an image-side surface S18. Light from the object passes sequentially through the surfaces S1 to S18 and is finally imaged onto the imaging surface (not shown).

[0084] Table 3 shows the basic parameters of the imaging system of Example 2, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm).

[0085]

[0086] Table 3

[0087] In this embodiment, the total effective focal length f of the lens group is 7.66 mm, half of the maximum field of view (Semi-FOV) of the lens group is 47.0°, and the entrance pupil diameter (EPD) of the lens group is 4.06 mm.

[0088] Table 4 shows the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28 and A30 that can be used for each of the aspherical mirrors S1 to S16 in Example 2, wherein each aspherical surface shape can be defined by formula (1) given in Example 1 above.

[0089] Face number A4 A6 A8 A10 A12 A14 A16 S1 -2.6273E-02 -8.3333E-03 -2.4855E-03 -6.2103E-04 -1.9752E-04 1.3496E-05 2.1639E-05 S2 -8.2658E-03 9.0609E-06 8.2212E-04 2.3555E-04 5.0046E-04 3.1018E-04 1.1472E-04 S3 -2.8001E-02 5.9167E-03 1.1317E-03 1.0915E-03 7.1568E-04 3.2533E-04 8.6750E-05 S4 -9.6040E-03 8.3658E-04 -3.0696E-03 -4.5491E-04 6.4436E-05 1.4712E-04 5.1721E-05 S5 9.6950E-02 2.3751E-02 3.1466E-03 7.0730E-05 -4.2526E-05 3.5249E-05 4.2460E-05 S6 5.4212E-02 2.0612E-02 6.0245E-03 1.4462E-03 3.0743E-04 3.0064E-05 1.5037E-05 S7 -1.6966E-01 -7.5533E-03 1.1902E-03 1.5378E-04 2.5083E-04 -1.4813E-05 5.3421E-05 S8 -1.8949E-01 7.2678E-03 7.2825E-03 1.0338E-03 8.0341E-04 5.8544E-05 2.0356E-04 S9 -2.8586E-01 1.2236E-02 1.5476E-02 8.9417E-04 -1.3005E-03 -9.1621E-04 2.4054E-04 S10 -4.9666E-01 2.1746E-02 2.6044E-02 9.3426E-03 -2.1727E-03 -2.4077E-03 -1.0752E-03 S11 -1.7529E+00 9.5254E-02 -2.8502E-02 2.7358E-02 -9.4682E-04 3.4037E-03 -2.5279E-03 S12 -2.9679E+00 4.5371E-01 -1.2057E-01 1.4154E-02 -8.9470E-03 8.2597E-03 -5.8214E-03 S13 -4.4034E+00 5.0162E-01 -7.8560E-02 -8.3197E-02 8.2629E-03 -9.4252E-04 -1.1348E-02 S14 -1.9031E-01 -2.3951E-01 1.5692E-01 -6.6157E-02 2.6819E-02 -6.7956E-03 -4.6730E-03 S15 2.2924E-01 8.4872E-01 -4.7116E-01 2.0711E-01 -7.2075E-02 1.6378E-02 -4.4700E-03 S16 -7.3220E+00 7.5740E-01 -4.9087E-01 1.1267E-01 -1.1211E-01 1.4245E-02 -4.1484E-02 Face number A18 A20 A22 A24 A26 A28 A30 S1 3.0109E-05 3.9559E-06 2.3635E-06 -2.5478E-06 4.4258E-06 -8.2643E-07 -4.1014E-07 S2 3.3219E-05 1.5816E-05 7.9638E-06 1.5553E-07 -3.6445E-06 1.0108E-06 -1.8925E-07 S3 1.3665E-05 1.4416E-05 7.5626E-07 -6.9255E-07 -3.8789E-06 2.3579E-06 -2.8261E-06 S4 -2.8299E-06 -6.5181E-06 -5.1533E-06 -1.4733E-07 2.2414E-06 4.8515E-06 4.3218E-07 S5 -1.0264E-06 -5.1523E-06 -8.6846E-06 5.6208E-07 1.6720E-06 4.1908E-06 -1.3583E-06 S6 -6.4897E-07 1.8594E-06 -3.9276E-06 1.2336E-06 1.5794E-06 2.5718E-06 -2.8552E-06 S7 1.3332E-05 1.8936E-05 7.8023E-06 1.0686E-06 -5.4870E-07 -9.3902E-07 8.2920E-07 S8 5.6844E-05 6.8325E-05 1.1074E-05 1.0283E-05 -7.8309E-06 1.6793E-06 -1.7150E-06 S9 5.8638E-04 3.2049E-04 7.9172E-05 -4.2919E-05 -5.3485E-05 -2.3175E-05 -1.3314E-05 S10 6.7525E-04 7.4518E-04 4.4099E-04 5.1963E-05 -9.6507E-05 -8.4744E-05 -3.7149E-05 S11 -1.5958E-04 8.2325E-04 8.5902E-04 2.2229E-04 -1.6186E-04 -1.1026E-04 -1.1275E-04 S12 2.2095E-03 1.0086E-03 -1.4644E-04 -5.8375E-04 1.9312E-04 1.7788E-04 -9.9585E-05 S13 6.6335E-03 -3.9378E-03 -7.9071E-04 3.9317E-04 6.9884E-05 -1.7898E-04 -9.2737E-05 S14 9.1527E-04 -4.6841E-03 1.9769E-03 -1.7749E-03 -9.4689E-04 1.3169E-05 -5.1680E-04 S15 8.4995E-03 -1.4812E-02 1.2364E-02 -5.3320E-03 1.1661E-03 5.0843E-04 -1.6800E-04 S16 1.1544E-02 -2.0948E-02 4.5748E-03 -5.5016E-03 5.6739E-04 -1.9185E-03 2.2908E-04

[0090] Table 4

[0091] Figure 9A The on-axis chromatic aberration curve of the imaging system of Embodiment 2 is shown, which represents the deviation of the convergence focal point of light of different wavelengths after passing through the imaging lens. Figure 9B The astigmatism curves of the imaging system of Example 2 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 9C The distortion curves of the imaging system of Example 2 are shown, which represent the distortion magnitude values ​​corresponding to different image heights. Figure 9D The magnification chromatic aberration curve of the imaging system of Example 2 is shown, which represents the deviation of different image heights on the imaging plane after light passes through the system. According to Figures 9A to 9D It can be seen that the imaging system given in Example 2 can achieve good imaging quality.

[0092] like Figures 6 to 8 As shown, the imaging systems 210, 220, and 230 each include a second spacer element P2, a third spacer element P3, a fourth spacer element P4, a fifth spacer element P5, a sixth spacer element P6, and a seventh spacer element P7. Specifically, the second spacer element P2 is disposed between the second lens E2 and the third lens E3 and contacts the image-side surface of the second lens E2; the third spacer element P3 is disposed between the third lens E3 and the fourth lens E4 and contacts the image-side surface of the third lens E3; the fourth spacer element P4 is disposed between the fourth lens E4 and the fifth lens E5 and contacts the image-side surface of the fourth lens E4; the fifth spacer element P5 is disposed between the fifth lens E5 and the sixth lens E6 and contacts the image-side surface of the fifth lens E5; the sixth spacer element P6 is disposed between the sixth lens E6 and the seventh lens E7 and contacts the image-side surface of the sixth lens E6; and the seventh spacer element P7 is disposed between the seventh lens E7 and the eighth lens E8 and contacts the image-side surface of the seventh lens E7. The aforementioned multiple spacer elements can block excess external light from entering, allowing the lens to better support the lens barrel and enhancing the structural stability of imaging systems 210, 220, and 230.

[0093] Example 3

[0094] The following is for reference Figures 10 to 13D An imaging system according to Embodiment 3 of this application is described. Figures 10 to 12 Cross-sectional schematic diagrams of three imaging systems according to Embodiment 3 of this application are shown respectively.

[0095] like Figures 10 to 12As shown, imaging systems 310, 320, and 330 each include a lens barrel P0, lens groups E1 to E8, and multiple spacer elements P2 to P7. In some cases, imaging systems 310, 320, and 330 may include the same lens groups E1 to E8. Specifically, the lens groups, from the object side to the image side, sequentially include: 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.

[0096] In some examples, the first lens E1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens E2 has negative optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens E3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being concave. The fourth lens E4 has positive optical power, with its object-side surface S7 being concave and its image-side surface S8 being convex. The fifth lens E5 has negative optical power, with its object-side surface S9 being concave and its image-side surface S10 being concave. The sixth lens E6 has negative optical power, with its object-side surface S11 being convex and its image-side surface S12 being concave. The seventh lens E7 has positive optical power, with its object-side surface S13 being convex and its image-side surface S14 being convex. The eighth lens E8 has negative optical power, with its object-side surface S15 being concave and its image-side surface S16 being concave. The filter (not shown) has an object-side surface S17 and an image-side surface S18. Light from the object passes sequentially through the surfaces S1 to S18 and is finally imaged onto the imaging surface (not shown).

[0097] Table 5 shows the basic parameters of the imaging system of Example 3, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm).

[0098]

[0099]

[0100] Table 5

[0101] In this embodiment, the total effective focal length f of the lens group is 7.49 mm, half of the maximum field of view (Semi-FOV) of the lens group is 47.7°, and the entrance pupil diameter (EPD) of the lens group is 3.97 mm.

[0102] Table 6 shows the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28 and A30 that can be used for each of the aspherical surfaces S1 to S16 in Example 3, wherein each aspherical surface shape can be defined by formula (1) given in Example 1 above.

[0103]

[0104]

[0105] Table 6

[0106] Figure 13A The on-axis chromatic aberration curve of the imaging system of Embodiment 3 is shown, which represents the deviation of the convergence focal point of light of different wavelengths after passing through the imaging lens. Figure 13B The astigmatism curves of the imaging system of Example 3 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 13C The distortion curves of the imaging system of Example 3 are shown, which represent the distortion magnitude values ​​corresponding to different image heights. Figure 13D The magnification chromatic aberration curve of the imaging system of Example 3 is shown, which represents the deviation of different image heights on the imaging plane after light passes through the system. According to Figures 13A to 13D It can be seen that the imaging system given in Example 3 can achieve good imaging quality.

[0107] like Figures 10 to 12 As shown, the imaging systems 310, 320, and 330 each include a second spacer element P2, a third spacer element P3, a fourth spacer element P4, a fifth spacer element P5, a sixth spacer element P6, and a seventh spacer element P7. Specifically, the second spacer element P2 is disposed between the second lens E2 and the third lens E3 and contacts the image-side surface of the second lens E2; the third spacer element P3 is disposed between the third lens E3 and the fourth lens E4 and contacts the image-side surface of the third lens E3; the fourth spacer element P4 is disposed between the fourth lens E4 and the fifth lens E5 and contacts the image-side surface of the fourth lens E4; the fifth spacer element P5 is disposed between the fifth lens E5 and the sixth lens E6 and contacts the image-side surface of the fifth lens E5; the sixth spacer element P6 is disposed between the sixth lens E6 and the seventh lens E7 and contacts the image-side surface of the sixth lens E6; and the seventh spacer element P7 is disposed between the seventh lens E7 and the eighth lens E8 and contacts the image-side surface of the seventh lens E7. The aforementioned multiple spacer elements can block excess external light from entering, allowing the lens to better support the lens barrel and enhancing the structural stability of imaging systems 310, 320, and 330.

[0108] Table 7 shows the basic parameters of the spacer elements P2 to P7 and the lens barrel P0 of the three imaging systems of Examples 1 to 3. The unit of each parameter in Table 7 is millimeters (mm).

[0109]

[0110]

[0111] Table 7

[0112] In summary, Examples 1 to 3 respectively satisfy the relationships shown in Table 8.

[0113] Conditional / Example 1-1 1-2 1-3 2-1 2-2 2-3 3-1 3-2 3-3 f / TAN(Semi-FOV)*(d6s-D2m) 23.71 13.53 10.66 19.32 6.80 19.32 16.60 17.43 17.39 f8*(D7s-D5s) -34.89 -34.89 -29.60 -28.60 -28.60 -28.60 -20.90 -27.13 -26.05 (EP67+EP34)*R15 -5.88 -5.64 -7.00 -6.94 -6.86 -6.94 -7.85 -7.72 -7.72 D2s / (N2-N1) / 10 8.13 10.66 10.66 4.57 6.21 4.57 6.79 8.41 8.41 (f*T67) / (T56*EP67) 14.97 14.97 10.43 10.78 10.78 10.78 9.62 9.89 9.89 (D0s-d2s) / (d0s-d2s)*(EPD / T78) 8.83 9.11 10.00 9.25 10.57 10.55 15.17 15.71 16.68 D4s / D3s+f1 / R1 3.59 3.23 3.25 4.17 3.78 4.17 3.41 3.41 3.45 CP3*f2+CP4*f6 -1.90 -2.96 -1.84 -0.90 -1.11 -0.90 -1.06 -1.06 -1.06 (V1-V4)*EP56 4.04 4.04 4.30 13.27 13.27 13.27 7.78 15.45 15.45 D3m*CT1+D4m*EP23 7.51 9.22 9.35 7.09 8.56 7.09 7.23 7.20 7.30 (D6m-D5m)*d5m 12.46 12.46 20.20 18.62 18.62 18.62 10.49 26.19 25.27

[0114] Table 8

[0115] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An imaging system, comprising a lens group, a plurality of spacer elements, and a lens barrel for accommodating the lens group and the plurality of spacer elements, wherein, the lens group consists of 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 from the object side to the image side along the optical axis, where, the first lens has a positive optical power; the second lens has a negative optical power; the third lens has a positive optical power; the sixth lens has a negative optical power; the seventh lens has a positive optical power; and the eighth lens has a negative optical power; the plurality of spacer elements includes: a second spacer element, disposed on the image side of the second lens and in contact with the image side surface of the second lens; a sixth spacer element, disposed on the image side of the sixth lens and in contact with the image side surface of the sixth lens; and a seventh spacer element, disposed on the image side of the seventh lens and in contact with the image side surface of the seventh lens; the imaging system satisfies: 5 < (D0s - d2s) / (d0s - d2s) * (EPD / T78) < 20, where, D0s is the outer diameter of the object side end of the lens barrel, d0s is the inner diameter of the object side end of the lens barrel, d2s is the inner diameter of the object side surface of the second spacer element, EPD is the entrance pupil diameter of the lens group, and T78 is the air gap between the seventh lens and the eighth lens along the optical axis.

2. The imaging system according to claim 1, wherein, the plurality of spacer elements further includes: a fifth spacer element, disposed on the image side of the fifth lens and in contact with the image side surface of the fifth lens; the imaging system satisfies: 1 < R11 / R12 < 2, and -40mm 2 <f8*(D7s-D5s)<-15mm 2 ; where, R11 is the curvature radius of the object side surface of the sixth lens, R12 is the curvature radius of the image side surface of the sixth lens, f8 is the effective focal length of the eighth lens, D5s is the outer diameter of the object side surface of the fifth spacer element, and D7s is the outer diameter of the object side surface of the seventh spacer element.

3. The imaging system according to claim 1, wherein, the plurality of spacer elements further includes: a third spacer element, disposed on the image side of the third lens and in contact with the image side surface of the third lens; and a fourth spacer element, disposed on the image side of the fourth lens and in contact with the image side surface of the fourth lens; the imaging system satisfies: -15mm 2 <(EP67+EP34)*R15<0mm 2 , where, EP34 is the distance along the optical axis from the image side surface of the third spacer element to the object side surface of the fourth spacer element, EP67 is the distance along the optical axis from the image side surface of the sixth spacer element to the object side surface of the seventh spacer element, and R15 is the curvature radius of the object side surface of the eighth lens.

4. The imaging system according to claim 1, wherein, the plurality of spacer elements further includes: a third spacer element, disposed on the image side of the third lens and in contact with the image side surface of the third lens; and a fourth spacer element, disposed on the image side of the fourth lens and in contact with the image side surface of the fourth lens; the imaging system satisfies: 2 < D4s / D3s + f1 / R1 < 6, Wherein, f1 is the effective focal length of the first lens, R1 is the radius of curvature of the object side surface of the first lens, D3s is the outer diameter of the object side surface of the third spacer element, and D4s is the outer diameter of the object side surface of the fourth spacer element.

5. The imaging system according to claim 1, characterized in that, The plurality of spacer elements also include: A third spacer element is disposed on the image side of the third lens and contacts the image side surface of the third lens; and A fourth spacer element is disposed on the image side of the fourth lens and in contact with the image side surface of the fourth lens; The imaging system satisfies: -4mm 2 <CP3*f2+CP4*f6≤-0.28mm 2 , Wherein, CP3 is the maximum thickness of the third spacer element, CP4 is the maximum thickness of the fourth spacer element, f2 is the effective focal length of the second lens, and f6 is the effective focal length of the sixth lens.

6. The imaging system according to claim 1, characterized in that, The imaging system satisfies: The plurality of spacer elements also include: A third spacer element is disposed on the image side of the third lens and contacts the image side surface of the third lens; and A fourth spacer element is disposed on the image side of the fourth lens and in contact with the image side surface of the fourth lens; 5mm 2 <D3m*CT1+D4m*EP23<12mm 2 , Wherein, D3m is the outer diameter of the image side of the third spacer element, D4m is the outer diameter of the image side of the fourth spacer element, CT1 is the center thickness of the first lens, and EP23 is the distance along the optical axis from the image side of the second spacer element to the object side of the third spacer element.

7. The imaging system according to claim 1, characterized in that, The plurality of spacers further includes: a fifth spacer, disposed on the image side of the fifth lens and in contact with the image side surface of the fifth lens; The imaging system satisfies: 7mm 2 <(D6m-D5m)*d5m<29mm 2 , Wherein, D5m is the outer diameter of the image-side surface of the fifth spacer element, D6m is the outer diameter of the image-side surface of the sixth spacer element, and d5m is the inner diameter of the image-side surface of the fifth spacer element.

8. The imaging system according to claim 1, characterized in that, The plurality of spacers further includes: a fifth spacer, disposed on the image side of the fifth lens and in contact with the image side surface of the fifth lens; The imaging system satisfies: 1mm < (V1-V4)*EP56 < 28mm Wherein, V1 is the Abbe number of the first lens, V4 is the Abbe number of the fourth lens, and EP56 is the distance along the optical axis from the image side of the fifth spacer element to the object side of the sixth spacer element.

9. The imaging system according to any one of claims 1-8, characterized in that, The imaging system satisfies: 0.8mm <D2s / (N2-N1) / 10<15mm, Wherein, D2s is the outer diameter of the object side of the second spacer element, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

10. The imaging system according to any one of claims 1-8, characterized in that, The imaging system satisfies: 5 < (f*T67) / (T56*EP67) < 21, Where f is the total effective focal length of the imaging system, T56 is the air gap between the fifth lens and the sixth lens along the optical axis, T67 is the air gap between the sixth lens and the seventh lens along the optical axis, and EP67 is the distance from the image side of the sixth spacer element to the object side of the seventh spacer element along the optical axis.

11. The imaging system according to any one of claims 1-8, characterized in that, At least one of the object-side surface and the image-side surface of at least one of the first lens to the eighth lens is aspherical, and at least one of the object-side surface and the image-side surface of at least one of the first lens to the eighth lens has at least one inflection point, wherein the absolute value of the effective focal length of the eighth lens is less than the absolute value of the effective focal length of any one of the first lens to the seventh lens.

12. The imaging system according to any one of claims 1-8, characterized in that, The imaging system satisfies: Ri / R(i+1)>0, and Ri>0, i=1, 2, 3, 4 or 5, Wherein, when i is 1, Ri represents the radius of curvature of the object-side surface of the first lens, and R(i+1) represents the radius of curvature of the image-side surface of the first lens; when i is 2, Ri represents the radius of curvature of the image-side surface of the first lens, and R(i+1) represents the radius of curvature of the object-side surface of the second lens; when i is 3, Ri represents the radius of curvature of the object-side surface of the second lens, and R(i+1) represents the radius of curvature of the image-side surface of the second lens; when i is 4, Ri represents the radius of curvature of the image-side surface of the second lens, and R(i+1) represents the radius of curvature of the object-side surface of the third lens; when i is 5, Ri represents the radius of curvature of the object-side surface of the third lens, and R(i+1) represents the radius of curvature of the image-side surface of the third lens.

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