Imaging system

Abstract

The application discloses an imaging system, which comprises, in sequence from the object side to the image side along the optical axis, a first lens, a second lens with positive refractive power, a third lens, a fourth lens, a fifth lens with positive refractive power, a sixth lens, a seventh lens with positive refractive power, an eighth lens with positive refractive power, a ninth lens with negative refractive power, a tenth lens with negative refractive power, an eleventh lens with positive refractive power, a twelfth lens with positive refractive power and a thirteenth lens with positive refractive power. The number of lenses with refractive power in the imaging system is thirteen.

Description

Technical Field

[0001] This application relates to the field of optical components, and more specifically, to an imaging system. Background Technology

[0002] With societal development, smartphones have become increasingly portable and feature-rich, making mobile photography a popular activity. However, the size of smartphones limits the applications of their cameras. To address this issue, more and more external lenses compatible with smartphones have emerged as auxiliary lenses, catering to diverse photographic functions and application scenarios.

[0003] Currently, external detachable lenses that are installed on the built-in lens of mobile phones to improve the image quality of mobile phones still cannot meet the needs of users. In particular, for external detachable telephoto lenses, while ensuring that the mobile phone can achieve telephoto shooting after the external lens is installed, it is impossible to achieve small distortion, high illumination and high image quality, resulting in large distortion, dark image brightness and poor image quality.

[0004] Therefore, there is an urgent need for an external telephoto lens that can be used in combination with a regular mobile phone lens, so that the overall camera lens can meet the characteristics of telephoto while having low distortion, high illumination and high image quality, thereby realizing the telephoto shooting function. Summary of the Invention

[0005] This application provides an imaging system comprising, along the optical axis from the object side to the image side, the following lenses in sequence: a first lens having positive or negative optical power; a second lens having positive optical power; a third lens having positive or negative optical power; a fourth lens having positive or negative optical power; a fifth lens having positive optical power; a sixth lens having positive or negative optical power; a seventh lens having positive optical power; an eighth lens having positive optical power; a ninth lens having negative optical power; a tenth lens having negative optical power; an eleventh lens having positive optical power; a twelfth lens having positive optical power; and a thirteenth lens having positive optical power. The number of lenses with optical power in the imaging system is thirteen.

[0006] In one embodiment, the optical power of the first lens and the third lens have opposite positive and negative attributes, and the optical power of the third lens and the fourth lens have opposite positive and negative attributes.

[0007] In one embodiment, the object-side surface of the first lens is convex; the object-side surface of the second lens is convex; the object-side surface of the third lens is concave, and the image-side surface is concave; or, the object-side surface of the third lens is convex, and the image-side surface is convex; the object-side surface of the fourth lens is either convex or concave; the object-side surface of the fifth lens is either convex or concave, and the image-side surface is convex; the object-side surface of the sixth lens is convex, and the image-side surface is concave; or, the object-side surface of the sixth lens is concave, and the image-side surface is convex; the object-side surface of the seventh lens is convex; the object-side surface of the eighth lens is convex, and the image-side surface is concave; the object-side surface of the ninth lens is convex, and the image-side surface is concave; both the object-side surface and the image-side surface of the tenth lens are concave; both the object-side surface and the image-side surface of the eleventh lens are convex; the image-side surface of the twelfth lens is convex; and both the object-side surface and the image-side surface of the thirteenth lens are convex.

[0008] In one embodiment, the imaging system further includes an imaging lens located on the image side of the thirteenth lens, the imaging lens comprising a plurality of lenses.

[0009] In one embodiment, the second lens, the third lens, and the fourth lens form a cemented triplet lens group, the sixth lens and the seventh lens form a cemented doublet lens group, the eighth lens and the ninth lens form a cemented doublet lens group, and the tenth lens and the eleventh lens form a cemented doublet lens group.

[0010] In one embodiment, the first lens and the second lens form a cemented doublet lens group, the third lens and the fourth lens form a cemented doublet lens group, the eighth lens and the ninth lens form a cemented doublet lens group, and the tenth lens and the eleventh lens form a cemented doublet lens group.

[0011] In one embodiment, the imaging system satisfies: 0.08≤f9 / f≤0.24, where f9 is the effective focal length of the ninth lens and f is the effective focal length of the imaging system.

[0012] In one embodiment, the imaging system satisfies at least one of the following conditions: 0.14≤f10 / f≤0.32, -0.45≤f11 / f≤-0.32, where f10 is the effective focal length of the tenth lens, f11 is the effective focal length of the eleventh lens, and f is the effective focal length of the imaging system.

[0013] In one embodiment, the imaging system satisfies: -1.35≤f13 / f≤-0.7, where f13 is the effective focal length of the thirteenth lens and f is the effective focal length of the imaging system.

[0014] In one embodiment, the imaging system satisfies: 1.1≤fd1 / f≤1.8, where fd1 is the combined effective focal length of the eighth and ninth lenses, and f is the effective focal length of the imaging system.

[0015] In one embodiment, the imaging system satisfies: 2.15≤fa / fb≤2.5, where fa is the combined effective focal length of the first to ninth lenses, and fb is the combined effective focal length of the tenth to thirteenth lenses.

[0016] In one embodiment, the imaging system includes an aperture stop disposed between the image side of the thirteenth lens and the imaging lens.

[0017] In one embodiment, the imaging system satisfies at least one of the following conditions: 0.15≤Thb / TTa≤0.4, 0.15≤Et / TTa≤0.25, 1.9≤D1 / Ed≤2.5, where Thb is the on-axis distance from the object side of the tenth lens to the image side of the thirteenth lens, TTa is the on-axis distance from the object side of the first lens to the image side of the thirteenth lens, Et is the on-axis distance from the image side of the thirteenth lens to the aperture stop, D1 is the optical aperture of the object side of the first lens, and Ed is the light-transmitting aperture of the aperture stop.

[0018] In one embodiment, the imaging system satisfies at least one of the following conditions: -1.80≤f1 / f≤1.42, -1.40≤f2 / f≤-0.7, -1.1≤f3 / f≤0.42, -1≤f4 / f≤0.89, -3.8≤f5 / f≤-1.15, 0.4≤|f6 / f|≤9, -1.7≤f7 / f≤-0.25, -0.76≤f12 / f≤-0.38, where f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, f7 is the effective focal length of the seventh lens, f12 is the effective focal length of the twelfth lens, and f is the effective focal length of the imaging system.

[0019] In one embodiment, the imaging system satisfies at least one of the following conditions: 25≤vd3≤95.2, 18≤vd5≤95.2, 18≤vd7≤35, 55≤vd13≤95.2, where vd3 is the Abbe number of the third lens, vd5 is the Abbe number of the fifth lens, vd7 is the Abbe number of the seventh lens, and vd13 is the Abbe number of the thirteenth lens.

[0020] In one embodiment, the imaging system satisfies at least one of the following conditions: -1.68 ≤ f1 / f ≤ 1.34, -1.32 ≤ f2 / f ≤ -0.73, -1.05 ≤ f3 / f ≤ 0.4, -0.95 ≤ f4 / f ≤ 0.85, -3.57 ≤ f5 / f ≤ -1.22, 0.45 ≤ |f6 / f| ≤ 8.75, -1.63 ≤ f7 / f ≤ -0.3, 0.12 ≤ f9 / f ≤ 0.21, 0.17 ≤ f10 / f≤0.3, -0.44≤f11 / f≤-0.34, -0.7≤f12 / f≤-0.4, -1.3≤f13 / f≤-0.72, 1.13≤fd1 / f≤1.75, 2.18≤fa / fb≤2.4, 0.19≤Thb / TTa≤0.35, 29≤vd3≤82, 22≤vd5≤82, 20≤vd7≤30, 63≤vd13≤95.2, where f1 is the effective focal length of the first lens. f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, f7 is the effective focal length of the seventh lens, f9 is the effective focal length of the ninth lens, f10 is the effective focal length of the tenth lens, f11 is the effective focal length of the eleventh lens, f12 is the effective focal length of the twelfth lens, f13 is the effective focal length of the thirteenth lens, f is the effective focal length of the imaging system, fd1 is the combined effective focal length of the eighth and ninth lenses, fa is the combined effective focal length of the first to ninth lenses, fb is the combined effective focal length of the tenth to thirteenth lenses, Thb is the on-axis distance from the object side of the tenth lens to the image side of the thirteenth lens, TTa is the on-axis distance from the object side of the first lens to the image side of the thirteenth lens, vd3 is the Abbe number of the third lens, vd5 is the Abbe number of the fifth lens, vd7 is the Abbe number of the seventh lens, and vd13 is the Abbe number of the thirteenth lens.

[0021] This application provides an imaging system that employs multiple lenses (e.g., thirteen lenses). By rationally setting the optical power of each lens, the imaging system can possess telephoto characteristics, reduce optical distortion, improve relative illumination, and mitigate aberrations such as chromatic aberration and astigmatism. This enhances the imaging quality, achieving an absolute optical distortion |DIS| ≤ 2%, transverse chromatic aberration less than 3.5 μm, a center field-of-view MTF curve above 0.6 at a frequency of 230 lp / mm, an MTF curve above 0.2 across the entire field of view, and relative illumination ≥ 55%. Furthermore, when adapted to an imaging lens with a focal length of 22.48 mm, it can achieve an angular magnification of 2.35X, thus enabling the imaging system to possess superior telephoto capabilities. Attached Figure Description

[0022] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0023] Figure 1 This is a schematic diagram of the imaging system according to Embodiment 1 of this application;

[0024] Figure 2 This is a schematic diagram of the lens group included in the imaging system according to Embodiment 1 of this application;

[0025] Figure 3 The distortion curve of the imaging system according to Embodiment 1 of this application is shown.

[0026] Figure 4 This is a schematic diagram of the lens group included in the imaging system according to Embodiment 2 of this application;

[0027] Figure 5 This is a distortion curve diagram of the imaging system according to Embodiment 2 of this application;

[0028] Figure 6 This is a schematic diagram of the lens group included in the imaging system according to Embodiment 3 of this application;

[0029] Figure 7 This is a distortion curve diagram of the imaging system according to Embodiment 3 of this application;

[0030] Figure 8 This is a schematic diagram of the lens group included in the imaging system according to Embodiment 4 of this application;

[0031] Figure 9 The distortion curve of the imaging system according to Embodiment 4 of this application is shown.

[0032] Figure 10 This is a schematic diagram of the lens group included in the imaging system according to Embodiment 5 of this application;

[0033] Figure 11 This is a distortion curve diagram of the imaging system according to Embodiment 5 of this application. Detailed Implementation

[0034] To facilitate understanding of this application, a more complete description of the application will be provided below with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of the application and are not intended to limit the scope of the 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.

[0035] 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.

[0036] 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.

[0037] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging side is called the image-side surface of the lens.

[0038] 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.

[0039] 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 a 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.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The features, principles, and other aspects of this application will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] In an exemplary embodiment, the imaging system provided in this application may include a lens group and an imaging lens arranged sequentially along the optical axis from the object side to the image side, wherein each lens group and imaging lens includes multiple lenses. As an example, the lens group includes, sequentially 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, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, and a thirteenth lens, each having optical power, with the imaging lens located on the image side of the thirteenth lens. As an example, the lens group of this imaging system can be adapted to an imaging lens with a focal length of 22.48 mm.

[0042] In an exemplary embodiment, the imaging lens may be, for example, a mobile phone lens. Adapting the lens group in the imaging system enables the imaging system to have the characteristics of telephoto, high illumination, high image quality, and low distortion, thereby achieving better telephoto functionality. In some cases, the number of lenses included in the imaging lens can be arbitrarily set according to actual needs.

[0043] In an exemplary embodiment, the imaging system may further include an aperture stop for limiting the light beam, ensuring that the outgoing light rays from the lens group of the imaging system enter the imaging lens behind the aperture stop in parallel, ensuring that when the lens group of the imaging system is used as an auxiliary lens, it does not affect the use of the imaging lens as the main camera lens, thereby improving the imaging quality of the imaging system. Exemplarily, the aperture stop is disposed between the image-side surface of the thirteenth lens and the imaging lens.

[0044] In an exemplary embodiment, the first lens may have positive or negative optical power. When the optical power of the first lens is positive, both its object-side and image-side surfaces can be convex; when the optical power of the first lens is negative, its object-side surface can be convex, and its image-side surface can be concave. By setting the object-side surface of the first lens to be convex, it is beneficial to reduce the angle of incidence of field rays at the object-side surface, allowing light to enter the imaging system better, reducing the generation of aberrations and distortions, and thus achieving high image quality and reducing distortion.

[0045] In an exemplary embodiment, the second lens may have positive optical power, and its object-side surface may be convex. By setting the second lens as a positive lens and its object-side surface as convex, it is beneficial to control the trajectory of light incident on the second lens, further collect light, and allow light to enter the imaging system better, reducing spherical aberration and distortion, thus achieving high image quality and reducing distortion. As an example, the image-side surface of the second lens may be convex, concave, or flat.

[0046] In an exemplary embodiment, the third lens may have positive or negative optical power. When the optical power of the third lens is positive, both its object-side and image-side surfaces can be convex; when the optical power of the third lens is negative, both its object-side and image-side surfaces can be concave. By setting the third lens as a positive lens, with both its object-side and image-side surfaces being convex, it can better match the first and fourth lenses with negative optical power, effectively controlling the direction of light, reducing the degree of light divergence, making the outgoing light path more gradual, helping to reduce spherical aberration, and effectively correcting chromatic aberration, which is beneficial to achieving high image quality. By setting the third lens as a negative lens, with both its object-side and image-side surfaces being concave, it can better match the first and fourth lenses with positive optical power, effectively controlling the direction of light, helping to diverge the light converged by the first and second lenses, reducing spherical aberration, which is beneficial to achieving high image quality and ensuring tolerance performance.

[0047] In an exemplary embodiment, the fourth lens may have positive or negative optical power. When the optical power of the fourth lens is positive, its object-side surface may be convex; when the optical power of the fourth lens is negative, its object-side surface may be concave. By setting the fourth lens as a positive lens with a convex object-side surface, it can be better matched with the third lens with negative optical power, further focusing the light, reducing the divergence of the light, making the trajectory of the outgoing light more gradual, and introducing negative spherical aberration, which is beneficial for balancing the spherical aberration of the optical system and improving resolution. By setting the fourth lens as a negative lens with a concave object-side surface, it can be better matched with the third lens with positive optical power, causing the beam to change from a focusing tendency to a parallel light tendency, better realizing the light transition, reducing the generation of spherical aberration, and helping to achieve high image quality and ensure tolerance performance. As an example, the image-side surface of the fourth lens may be flat, concave, or convex.

[0048] In an exemplary embodiment, the second lens may have positive optical power, the third lens may have negative optical power, and the fourth lens may have positive optical power. The second lens, the third lens, and the fourth lens may constitute a cemented three-lens group.

[0049] In an exemplary embodiment, the first lens may have negative optical power, the second lens may have positive optical power, the third lens may have positive optical power, and the fourth lens may have negative optical power. The first lens and the second lens may form a cemented doublet lens group, and the third lens and the fourth lens may form a cemented doublet lens group.

[0050] In an exemplary embodiment, the fifth lens may have positive optical power, and its image-side surface may be convex. By setting the fifth lens as a positive lens with a convex image-side surface, it is beneficial to control the direction of light, converge the light, effectively limit the incident height of the light at the rear optical lens, effectively reduce the aperture size of the rear lens, facilitate the miniaturization of the lens, and effectively reduce the tolerance sensitivity of the lens. As an example, the object-side surface of the fifth lens may be concave or convex.

[0051] In an exemplary embodiment, the sixth lens may have positive or negative optical power. When the optical power of the sixth lens is positive, its object-side surface may be concave and its image-side surface may be convex; when the optical power of the sixth lens is negative, its object-side surface may be convex and its image-side surface may be concave.

[0052] In an exemplary embodiment, the seventh lens may have positive optical power, and its object-side surface may be convex. By rationally matching the optical power and lens shape of the sixth and seventh lenses, the direction of light is effectively controlled, and the light is further converged, which reduces the optical path and helps to reduce spherical aberration, thereby improving the image quality of the lens. As an example, the image-side surface of the seventh lens may be convex, concave, or flat.

[0053] In an exemplary embodiment, the sixth lens may have negative optical power and the seventh lens may have positive optical power. The sixth lens and the seventh lens may form a cemented doublet lens group, which can effectively correct the chromatic aberration generated by the first lens to the fifth lens and is conducive to achieving high image quality.

[0054] In an exemplary embodiment, the eighth lens may have positive optical power, and its object side may be convex and its image side may be concave.

[0055] In an exemplary embodiment, the ninth lens may have negative optical power, its object side may be convex, and its image side may be concave. By matching the positive and negative optical powers of the eighth and ninth lenses and their shapes, the direction of light can be effectively controlled, causing the light to converge and correct spherical aberration, astigmatism, and field curvature, thereby improving the lens's resolving power and ensuring its tolerance performance. The eighth and ninth lenses can form a cemented doublet lens group, which is beneficial for correcting chromatic aberration generated by the first to seventh lenses.

[0056] In an exemplary embodiment, the tenth lens may have negative optical power, and its object side may be concave, and its image side may be concave.

[0057] In an exemplary embodiment, the eleventh lens may have positive optical power, and its object side may be convex, and its image side may be convex.

[0058] In an exemplary embodiment, the tenth lens is a negative lens, and the eleventh lens is a positive lens. The tenth and eleventh lenses can form a cemented doublet lens group. By matching the positive and negative optical powers of the tenth and eleventh lenses and their shapes, the direction of light can be effectively controlled, causing the light to diverge. This facilitates the smooth transmission of light behind the lens and helps correct chromatic aberration. Simultaneously, by appropriately setting the optical powers of the tenth and eleventh lenses, and through their interaction with the eighth and ninth lenses, lens distortion can be effectively corrected, achieving a low-distortion effect.

[0059] In an exemplary embodiment, the twelfth lens may have positive optical power, and its image-side surface may be convex. By setting the twelfth lens as a positive lens with a convex image-side surface, it helps to control the direction of light, increases the ability to focus light, and changes the light from a divergent tendency to a parallel light tendency, which helps to reduce spherical aberration. Furthermore, it can be reasonably combined with a thirteenth lens with positive optical power to correct system distortion and achieve a low-distortion effect. As an example, the object-side surface of the twelfth lens may be concave, convex, or flat.

[0060] In an exemplary embodiment, the thirteenth lens may have positive optical power, and its object-side surface may be convex. By setting the thirteenth lens as a positive lens with a convex object-side surface, it helps to control the direction of light, further increasing the ability to focus light, and causing the light direction to change into parallel light transmission. This helps to better adapt to the mobile phone lens, allowing light to be smoothly transmitted to the optical system of the mobile phone lens, and also helps to correct aberrations in the optical system. As an example, the image-side surface of the thirteenth lens may be flat or convex.

[0061] In an exemplary embodiment, the imaging system according to this application satisfies: 0.08 ≤ f9 / f ≤ 0.24, where f9 is the effective focal length of the ninth lens and f is the effective focal length of the imaging system. Satisfying 0.08 ≤ f9 / f ≤ 0.24 allows for reasonable control of the focal length value of the ninth lens, effectively controlling the direction of light rays, causing light to converge, effectively correcting spherical aberration, astigmatism, and field curvature, thus improving the lens's resolving power and ensuring its tolerance performance. More specifically, f9 and f can further satisfy 0.12 ≤ f9 / f ≤ 0.21.

[0062] In an exemplary embodiment, the imaging system according to this application satisfies: 0.14 ≤ f10 / f ≤ 0.32, where f10 is the effective focal length of the tenth lens and f is the effective focal length of the imaging system. Satisfying 0.14 ≤ f10 / f ≤ 0.32 allows for reasonable control of the focal length value of the tenth lens. By coordinating the positive and negative focal lengths of the tenth and eleventh lenses, the direction of light can be effectively controlled, causing the light path to diverge. This facilitates the smooth transmission of light behind the lens and helps correct chromatic aberration. More specifically, f10 and f can further satisfy 0.17 ≤ f10 / f ≤ 0.3.

[0063] In an exemplary embodiment, the imaging system according to this application satisfies: -0.45 ≤ f11 / f ≤ -0.32, where f11 is the effective focal length of the eleventh lens and f is the effective focal length of the imaging system. Satisfying -0.45 ≤ f11 / f ≤ -0.32 allows for reasonable control of the focal length value of the eleventh lens. By coordinating the positive and negative focal lengths of the tenth and eleventh lenses, the direction of light can be effectively controlled, causing the light path to diverge. This facilitates the smooth transmission of light behind the lens and helps correct chromatic aberration. More specifically, f11 and f can further satisfy -0.44 ≤ f11 / f ≤ -0.34.

[0064] In an exemplary embodiment, the imaging system according to this application satisfies: -1.35 ≤ f13 / f ≤ -0.7, where f13 is the effective focal length of the thirteenth lens and f is the effective focal length of the imaging system. Satisfying -1.35 ≤ f13 / f ≤ -0.7, and reasonably controlling the ratio of the focal length of the thirteenth lens to the focal length of the imaging system, helps control the direction of light, further increases the ability to focus light, and makes the light path change to parallel light transmission. This helps to better adapt to the imaging lens, allowing light to be smoothly transmitted to the optical system of the imaging lens, helps to balance aberrations and eliminate transverse chromatic aberration, and effectively improves illumination. It also ensures that when the lens group is used as an external auxiliary lens, it does not affect the use of the imaging lens as the main camera lens, thus improving the imaging quality of the imaging system. More specifically, f13 and f can further satisfy -1.3 ≤ f13 / f ≤ -0.72.

[0065] In an exemplary embodiment, the imaging system according to this application satisfies: 1.1 ≤ fd1 / f ≤ 1.8, where fd1 is the combined effective focal length of the eighth and ninth lenses, and f is the effective focal length of the imaging system. Satisfying 1.1 ≤ fd1 / f ≤ 1.8, by reasonably setting the combined effective focal length of the eighth and ninth lenses, the trend of light can be effectively controlled, causing light to converge and effectively correct spherical aberration, astigmatism, and field curvature. This is beneficial for improving the lens's resolving power, ensuring the lens's tolerance performance, and also helps correct chromatic aberration generated by the first to seventh lenses. Furthermore, reasonably setting the combined effective focal length of the eighth and ninth lenses, so that it cooperates with the effective focal lengths of the tenth and eleventh lenses, effectively corrects lens distortion and achieves a low-distortion effect. More specifically, fd1 and f can further satisfy 1.13 ≤ fd1 / f ≤ 1.75.

[0066] In an exemplary embodiment, the imaging system according to this application satisfies the following condition: 2.15 ≤ fa / fb ≤ 2.5, where fa is the combined effective focal length of the first to ninth lenses, and fb is the combined effective focal length of the tenth to thirteenth lenses. Satisfying 2.15 ≤ fa / fb ≤ 2.5, and reasonably controlling the ratio of the combined effective focal length of the first to ninth lenses to the combined effective focal length of the tenth to thirteenth lenses, is beneficial for realizing the telephoto characteristics of the imaging system. It also improves the angular magnification of the imaging system, enabling an angular magnification of 2.35X when the lens group and imaging lens are used in combination. Furthermore, it effectively improves the illumination of the imaging system, thereby enabling the imaging system to have better telephoto capabilities. More specifically, fa and fb can further satisfy 2.18 ≤ fa / fb ≤ 2.4.

[0067] In an exemplary embodiment, the imaging system according to this application satisfies: -1.80 ≤ f1 / f ≤ 1.42, where f1 is the effective focal length of the first lens and f is the effective focal length of the imaging system. Satisfying -1.80 ≤ f1 / f ≤ 1.42, and reasonably controlling the ratio of the effective focal length of the first lens to the effective focal length of the imaging system, helps to reduce the incident angle of the field of view light on the object side, allowing light to enter the imaging system better, reducing the generation of aberrations and distortions, and contributing to high image quality and reduced distortion in the imaging system; it also facilitates cooperation with other lenses to correct chromatic aberration. More specifically, f1 and f can further satisfy -1.68 ≤ f1 / f ≤ 1.34.

[0068] In an exemplary embodiment, the imaging system according to this application satisfies: -1.40 ≤ f2 / f ≤ -0.7, where f2 is the effective focal length of the second lens and f is the effective focal length of the imaging system. Satisfying -1.40 ≤ f2 / f ≤ -0.7, and reasonably controlling the ratio of the effective focal length of the second lens to the effective focal length of the imaging system, helps to reduce spherical aberration and distortion, achieving high image quality and reducing distortion. More specifically, f2 and f can further satisfy -1.32 ≤ f2 / f ≤ -0.73.

[0069] In an exemplary embodiment, the imaging system according to this application satisfies: -1.1 ≤ f3 / f ≤ 0.42, where f3 is the effective focal length of the third lens and f is the effective focal length of the imaging system. Satisfying -1.1 ≤ f3 / f ≤ 0.42, and reasonably controlling the ratio of the effective focal length of the third lens to the effective focal length of the imaging system, helps to diverge the light rays converged by the first and second lenses, reduces spherical aberration, and allows the third lens to better cooperate with the second and fourth lenses, thereby eliminating chromatic aberration and achieving high image quality. More specifically, f3 and f can further satisfy -1.05 ≤ f3 / f ≤ 0.4.

[0070] In an exemplary embodiment, the imaging system according to this application satisfies: -1 ≤ f4 / f ≤ 0.89, where f4 is the effective focal length of the fourth lens and f is the effective focal length of the imaging system. Satisfying -1 ≤ f4 / f ≤ 0.89, and reasonably controlling the ratio of the effective focal length of the fourth lens to the effective focal length of the imaging system, allows the fourth lens to better cooperate with the third lens, thereby eliminating chromatic aberration, reducing spherical aberration, and contributing to high image quality. More specifically, f4 and f can further satisfy -0.95 ≤ f4 / f ≤ 0.85.

[0071] In an exemplary embodiment, the imaging system according to this application satisfies: -3.8 ≤ f5 / f ≤ -1.15, where f5 is the effective focal length of the fifth lens and f is the effective focal length of the imaging system. Satisfying -3.8 ≤ f5 / f ≤ -1.15, and reasonably controlling the ratio of the effective focal length of the fifth lens to the effective focal length of the imaging system, is beneficial for controlling the incident height of light, making the light transition smooth, effectively reducing the tolerance sensitivity of the lens, and improving the production yield of the lens. More specifically, f5 and f can further satisfy -3.57 ≤ f5 / f ≤ -1.22.

[0072] In an exemplary embodiment, the imaging system according to this application satisfies: 0.4 ≤ |f6 / f| ≤ 9, where f6 is the effective focal length of the sixth lens and f is the effective focal length of the imaging system. Satisfying 0.4 ≤ |f6 / f| ≤ 9, and reasonably controlling the ratio of the effective focal length of the sixth lens to the effective focal length of the imaging system, helps to reduce spherical aberration and improve lens resolution. Simultaneously, it facilitates the combination with the seventh lens to form a cemented lens group, effectively controlling the direction of light and converging the light, which helps to reduce lens tolerance sensitivity and improve lens production yield. More specifically, f6 and f can further satisfy 0.45 ≤ |f6 / f| ≤ 8.75.

[0073] In an exemplary embodiment, the imaging system according to this application satisfies: -1.7 ≤ f7 / f ≤ -0.25, where f7 is the effective focal length of the seventh lens and f is the effective focal length of the imaging system. Satisfying -1.7 ≤ f7 / f ≤ -0.25, and reasonably controlling the ratio of the effective focal length of the seventh lens to the effective focal length of the imaging system, helps to reduce spherical aberration and improve lens resolution. Simultaneously, it facilitates the combination with the sixth lens to form a cemented lens group, effectively controlling the direction of light and converging the light, which helps to reduce lens tolerance sensitivity and improve lens production yield. More specifically, f7 and f can further satisfy -1.63 ≤ f7 / f ≤ -0.3.

[0074] In an exemplary embodiment, the imaging system according to this application satisfies: -0.76 ≤ f12 / f ≤ -0.38, where f12 is the effective focal length of the thirteenth lens and f is the effective focal length of the imaging system. Satisfying -0.76 ≤ f12 / f ≤ -0.38 allows for reasonable control of the ratio of the focal length of the twelfth lens to the focal length of the imaging system, effectively controlling the light path and ensuring smooth transmission of the outgoing light. This helps eliminate chromatic aberration generated by the first to eleventh lenses, reduces spherical aberration, improves lens resolution, and further contributes to achieving low distortion, ensuring that the absolute value of optical distortion in the imaging system is ≤2%. More specifically, f12 and f can further satisfy -0.7 ≤ f12 / f ≤ -0.4.

[0075] In an exemplary embodiment, the imaging system according to this application satisfies the following condition: 0.15 ≤ Thb / TTa ≤ 0.4, where Thb is the on-axis distance from the object-side surface of the tenth lens to the image-side surface of the thirteenth lens, and TTa is the on-axis distance from the object-side surface of the first lens to the image-side surface of the thirteenth lens. Satisfying 0.15 ≤ Thb / TTa ≤ 0.4 allows for reasonable control of the ratio of the on-axis distance between the object-side surface of the tenth lens and the image-side surface of the thirteenth lens to that between the object-side surface of the first lens and the image-side surface of the thirteenth lens. This facilitates the proper arrangement of the tenth to thirteenth lenses within the lens group of the imaging system, controlling the overall length of the lens group and enabling miniaturization of the imaging system while meeting performance requirements. More specifically, Thb and TTa can further satisfy 0.19 ≤ Thb / TTa ≤ 0.35.

[0076] In an exemplary embodiment, the imaging system according to this application satisfies the following condition: 0.15 ≤ Et / TTa ≤ 0.25, where Et is the axial distance from the image side of the thirteenth lens to the aperture stop, and TTa is the axial distance from the object side of the first lens to the image side of the thirteenth lens. Satisfying 0.15 ≤ Et / TTa ≤ 0.25, and reasonably controlling the ratio of the axial distance from the image side of the thirteenth lens to the aperture stop to the axial distance from the object side of the first lens to the image side of the thirteenth lens, is beneficial for controlling the rear-end dimensions of the lens group in the imaging system, thereby achieving miniaturization and compactness of the imaging system.

[0077] In an exemplary embodiment, the imaging system according to this application satisfies: 1.9 ≤ D1 / Ed ≤ 2.5, where D1 is the full optical aperture of the object-side surface of the first lens, and Ed is the full light-transmitting aperture of the aperture stop. Satisfying 1.9 ≤ D1 / Ed ≤ 2.5, and reasonably controlling the ratio of the full optical aperture of the object-side surface of the first lens to the full light-transmitting aperture of the first aperture stop, is beneficial for lens miniaturization. Simultaneously, it increases the angular magnification of the imaging system, ensuring that the lens group, when used as an external auxiliary lens in combination with the imaging lens, can achieve an angular magnification of 2.35X, thereby enabling the imaging system to possess better telephoto capabilities.

[0078] In an exemplary embodiment, the imaging system according to this application can satisfy at least one of the following: 25≤vd3≤95.2, 18≤vd5≤95.2, 18≤vd7≤35, 55≤vd13≤95.2, where vd3 is the Abbe number of the third lens, vd5 is the Abbe number of the fifth lens, vd7 is the Abbe number of the seventh lens, and vd13 is the Abbe number of the thirteenth lens. By reasonably selecting the lens materials of the third, fifth, seventh, and thirteenth lenses, the transverse chromatic aberration of the imaging system can be effectively corrected, the generation of purple fringing in the imaging system can be avoided, and the imaging quality can be improved. More specifically, vd3, vd5, vd7, and vd13 can further satisfy at least one of the following: 29≤vd3≤82, 22≤vd5≤82, 20≤vd7≤30, 63≤vd13≤95.2.

[0079] In an exemplary embodiment, the optical distortion (DIS) of the imaging system of this application satisfies: |DIS|≤2%. The imaging system of this application has a low optical distortion value, that is, it has the characteristic of low distortion, which effectively reduces the degree of distortion at the edges of the image and better solves the problem that current external telephoto lenses cannot achieve low distortion.

[0080] In an exemplary embodiment, each of the first to thirteenth lenses in the imaging system of this application can be a spherical lens or an aspherical lens. This application does not specifically limit the number of spherical and aspherical lenses as needed. When image quality is a primary concern, the number of aspherical lenses can be increased, or even all lenses can be aspherical. An aspherical lens is characterized by a continuously changing curvature from its center to its periphery. Unlike a spherical lens, which has a constant curvature from its center to its periphery, an aspherical lens has better radius of curvature characteristics, offering advantages in improving distortion and astigmatism. Using aspherical lenses can minimize aberrations that occur during imaging, thereby improving the image quality of the lens. However, those skilled in the art should understand that, without departing from the technical solutions claimed in this application, the lens surface types constituting the lens group or imaging system can be changed to obtain the various results and advantages described in this specification. As an example, the first to thirteenth lenses in this application are all spherical lenses.

[0081] Those skilled in the art will understand that plastics have a large temperature coefficient of refractive index (dn / dt) and anomalous dispersion. A suitable amount of plastic material is beneficial for high and low temperature balance, but excessive plastic lenses are detrimental to system stability. Optical lenses made of glass can suppress the shift in back focus of the optical lens due to temperature changes, thereby improving system stability. Simultaneously, using glass avoids lens blurring caused by high and low temperature changes in the operating environment, thus preventing problems affecting the normal use of the lens. Using glass also facilitates heat-free lens operation. Furthermore, using glass can better correct system chromatic aberration, improve lens resolution, and reduce ghosting. As an example, the first to thirteenth lenses in this application are all made of glass.

[0082] This application provides an imaging system that employs multiple lenses (e.g., thirteen lenses). By rationally setting the optical power of each lens, the imaging system can possess telephoto characteristics, reduce optical distortion, improve relative illumination, and mitigate aberrations such as chromatic aberration and astigmatism. This enhances the imaging quality, achieving an absolute optical distortion |DIS| ≤ 2%, transverse chromatic aberration less than 3.5 μm, a center field-of-view MTF curve above 0.6 at a frequency of 230 lp / mm, an MTF curve above 0.2 across the entire field of view, and relative illumination ≥ 55%. Furthermore, when adapted to an imaging lens with a focal length of 22.48 mm, it can achieve an angular magnification of 2.35X, thus enabling the imaging system to possess superior telephoto capabilities.

[0083] However, those skilled in the art will understand that the number of lenses constituting the lens group or imaging system can be changed without departing from the technical solutions claimed in this application to obtain the various results and advantages described in this specification. For example, although thirteen lenses have been described as an example in the embodiments, the lens group is not limited to including thirteen lenses. If desired, the lens group may also include other numbers of lenses. Specific embodiments of the imaging system applicable to the above embodiments are further described below with reference to the accompanying drawings.

[0084] Example 1

[0085] The following is for reference Figure 1 and Figure 2 An imaging system according to Embodiment 1 of this application is described. Figure 1 A schematic diagram of the imaging system according to Embodiment 1 of this application is shown. Figure 2 A schematic diagram of the structure of the lens group 10 included in the imaging system according to Embodiment 1 of this application is shown.

[0086] like Figure 1As shown, the imaging system includes a lens group 10, an aperture stop, and an imaging lens 20 arranged sequentially along the optical axis from the object side to the image side. The lens group 10, arranged sequentially along the optical axis from the object side to the image side, includes: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a twelfth lens L12, and a thirteenth lens L13. The imaging system also includes an imaging plane IMA disposed on the image side of the imaging lens 20.

[0087] The first lens L1 has positive optical power, and its object side S1 is convex, and its image side S2 is convex.

[0088] The second lens L2 has positive optical power, and its object side S3 is convex, while its image side S4 is convex.

[0089] The third lens L3 has negative optical power, and its object side S4 is concave, as is its image side S5.

[0090] The fourth lens L4 has positive optical power, with its object side S5 being convex and its image side S6 being concave.

[0091] The fifth lens L5 has positive optical power, with its object side S7 being concave and its image side S8 being convex.

[0092] The sixth lens L6 has negative optical power, with its object side S9 being convex and its image side S10 being concave.

[0093] The seventh lens L7 has positive optical power, with its object side S10 being convex and its image side S11 being concave.

[0094] The eighth lens L8 has positive optical power, with its object side S12 being convex and its image side S13 being concave.

[0095] The ninth lens L9 has negative optical power, with its object side S13 being convex and its image side S14 being concave.

[0096] The tenth lens L10 has negative optical power, and its object side S15 is concave, as is its image side S16.

[0097] The eleventh lens L11 has positive optical power, and its object-side surface S16 is convex, as is its image-side surface S17.

[0098] The twelfth lens L12 has positive optical power, with its object side S18 being concave and its image side S19 being convex.

[0099] The thirteenth lens L13 has positive optical power, and its object side S20 is convex, while its image side S21 is convex.

[0100] The second lens L2, the third lens L3, and the fourth lens L4 form a cemented triplet lens group; the sixth lens L6 and the seventh lens L7 form a cemented doublet lens group; the eighth lens L8 and the ninth lens L9 form a cemented doublet lens group; and the tenth lens L10 and the eleventh lens L11 form a cemented doublet lens group.

[0101] The imaging system may also include an aperture stop STO, which may be positioned between the thirteenth lens L13 of the lens group 10 and the imaging lens 20. Light from the object passes sequentially through the first lens L1 to the thirteenth lens L13 of the lens group 10 and each lens of the imaging lens 20, and is finally imaged on the imaging plane IMA.

[0102] The first lens L1 to the thirteenth lens L13 of the lens group 10 are all made of glass.

[0103] Table 1 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of each lens in the lens group 10 of Embodiment 1, wherein the units of radius of curvature and thickness / distance are millimeters (mm).

[0104] Table 1

[0105]

[0106]

[0107] In this embodiment, when adapted to an imaging lens with a focal length of 22.48mm, the total effective focal length f of the imaging system is -52.80mm, the distance TTL between the object side surface S1 of the first lens L1 and the aperture stop S22 on the optical axis is 124.72mm, and the maximum semi-FOV of the imaging system is 7.00°.

[0108] In this embodiment, the MTF value is above 0.2 throughout the entire field of view. The MTF curve decreases smoothly and evenly from the center to the edge of the field of view. At a spatial frequency of 230 lp / mm, the MTF curve at the center field of view is above 0.6, indicating that the imaging system has good imaging quality and good detail resolution. Furthermore, the transaxial chromatic aberration of the longest and shortest wavelengths of the imaging system is controlled within -1.5 μm to 1.5 μm, indicating that the imaging system can effectively correct chromatic aberration at the edge of the field of view and the secondary spectrum of the entire image plane. At the same time, the relative illumination value of the imaging system is 56% at the maximum half field of view, indicating that the imaging system has good relative illumination.

[0109] Figure 3 The distortion curve of the imaging system of Embodiment 1 is shown, representing the distortion magnitude corresponding to different field of view angles. It can be seen from the figure that the absolute value of the optical distortion at the edge field of view in Embodiment 1 is 1.3%. According to... Figure 3As can be seen, the imaging system given in Example 1 has the characteristics of low distortion and can achieve good imaging quality.

[0110] Example 2

[0111] Figure 4 A schematic diagram of the structure of the lens group 10 included in the imaging system according to Embodiment 2 of this application is shown.

[0112] The following is for reference Figure 1 The imaging system includes a lens group 10, an aperture stop STO, and an imaging lens 20 arranged sequentially along the optical axis from the object side to the image side. Among them, such as... Figure 4 As shown, the lens group 10 includes, in sequence along the optical axis from the object side to the image side: first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, eighth lens L8, ninth lens L9, tenth lens L10, eleventh lens L11, twelfth lens L12, and thirteenth lens L13. The imaging system also includes an imaging plane IMA disposed on the image side of the imaging lens 20.

[0113] The first lens L1 has positive optical power, and its object side S1 is convex, and its image side S2 is convex.

[0114] The second lens L2 has positive optical power, and its object side S3 is convex, while its image side S4 is convex.

[0115] The third lens L3 has negative optical power, and its object side S4 is concave, as is its image side S5.

[0116] The fourth lens L4 has positive optical power, with its object side S5 being convex and its image side S6 being concave.

[0117] The fifth lens L5 has positive optical power, with its object side S7 being concave and its image side S8 being convex.

[0118] The sixth lens L6 has negative optical power, with its object side S9 being convex and its image side S10 being concave.

[0119] The seventh lens L7 has positive optical power, and its object side S10 is convex, and its image side S11 is convex.

[0120] The eighth lens L8 has positive optical power, with its object side S12 being convex and its image side S13 being concave.

[0121] The ninth lens L9 has negative optical power, with its object side S13 being convex and its image side S14 being concave.

[0122] The tenth lens L10 has negative optical power, and its object side S15 is concave, as is its image side S16.

[0123] The eleventh lens L11 has positive optical power, and its object-side surface S16 is convex, as is its image-side surface S17.

[0124] The twelfth lens L12 has positive optical power, with its object side S18 being concave and its image side S19 being convex.

[0125] The thirteenth lens L13 has positive optical power, and its object side S20 is convex, while its image side S21 is convex.

[0126] The second lens L2, the third lens L3, and the fourth lens L4 form a cemented triplet lens group; the sixth lens L6 and the seventh lens L7 form a cemented doublet lens group; the eighth lens L8 and the ninth lens L9 form a cemented doublet lens group; and the tenth lens L10 and the eleventh lens L11 form a cemented doublet lens group.

[0127] The imaging system may also include an aperture stop STO, which may be positioned between the thirteenth lens L13 of the lens group 10 and the imaging lens 20. Light from the object passes sequentially through the first lens L1 to the thirteenth lens L13 of the lens group 10 and each lens of the imaging lens 20, and is finally imaged on the imaging plane IMA.

[0128] The first lens L1 to the thirteenth lens L13 of the lens group 10 are all made of glass.

[0129] Table 2 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of each lens in the lens group 10 of Embodiment 2, wherein the units of radius of curvature and thickness / distance are millimeters (mm).

[0130] Table 2

[0131]

[0132] In this embodiment, when adapted to an imaging lens with a focal length of 22.48mm, the total effective focal length f of the imaging system is -52.81mm, the distance TTL between the object side surface S1 of the first lens L1 and the aperture stop S22 on the optical axis is 122.07mm, and the maximum semi-FOV of the imaging system is 7.10°.

[0133] In this embodiment 2, the MTF value is above 0.2 throughout the entire field of view. The MTF curve decreases smoothly and evenly from the center to the edge of the field of view. At a spatial frequency of 230 lp / mm, the MTF curve of the center field of view is above 0.6, indicating that the imaging system has good imaging quality and good detail resolution. Furthermore, the transaxial chromatic aberration of the longest and shortest wavelengths of the imaging system is controlled within -1 μm to 3.5 μm, indicating that the imaging system can effectively correct the chromatic aberration of the edge field of view and the secondary spectrum of the entire image plane. At the same time, the relative illumination value of the imaging system is 55% at the maximum half field of view, indicating that the imaging system has good relative illumination.

[0134] Figure 5 The distortion curve of the imaging system of Embodiment 2 is shown, representing the distortion magnitude corresponding to different field of view angles. It can be seen from the figure that the absolute value of the optical distortion at the edge field of view in Embodiment 2 is 1.1%. According to... Figure 5 As can be seen, the imaging system given in Example 2 has the characteristics of low distortion and can achieve good imaging quality.

[0135] Example 3

[0136] Figure 6 A schematic diagram of the structure of the lens group 10 included in the imaging system according to Embodiment 3 of this application is shown.

[0137] The following is for reference Figure 1 The imaging system includes a lens group 10, an aperture stop STO, and an imaging lens 20 arranged sequentially along the optical axis from the object side to the image side. Among them, such as... Figure 6 As shown, the lens group 10 includes, in sequence along the optical axis from the object side to the image side: first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, eighth lens L8, ninth lens L9, tenth lens L10, eleventh lens L11, twelfth lens L12, and thirteenth lens L13. The imaging system also includes an imaging plane IMA disposed on the image side of the imaging lens 20.

[0138] The first lens L1 has positive optical power, and its object side S1 is convex, and its image side S2 is convex.

[0139] The second lens L2 has positive optical power, and its object side S3 is convex, while its image side S4 is convex.

[0140] The third lens L3 has negative optical power, and its object side S4 is concave, as is its image side S5.

[0141] The fourth lens L4 has positive optical power, with its object side S5 being convex and its image side S6 being concave.

[0142] The fifth lens L5 has positive optical power, with its object side S7 being concave and its image side S8 being convex.

[0143] The sixth lens L6 has negative optical power, with its object side S9 being convex and its image side S10 being concave.

[0144] The seventh lens L7 has positive optical power, with its object side S10 being convex and its image side S11 being concave.

[0145] The eighth lens L8 has positive optical power, with its object side S12 being convex and its image side S13 being concave.

[0146] The ninth lens L9 has negative optical power, with its object side S13 being convex and its image side S14 being concave.

[0147] The tenth lens L10 has negative optical power, and its object side S15 is concave, as is its image side S16.

[0148] The eleventh lens L11 has positive optical power, and its object-side surface S16 is convex, as is its image-side surface S17.

[0149] The twelfth lens L12 has positive optical power, with its object side S18 being concave and its image side S19 being convex.

[0150] The thirteenth lens L13 has positive optical power, and its object side S20 is convex, while its image side S21 is convex.

[0151] The second lens L2, the third lens L3, and the fourth lens L4 form a cemented triplet lens group; the sixth lens L6 and the seventh lens L7 form a cemented doublet lens group; the eighth lens L8 and the ninth lens L9 form a cemented doublet lens group; and the tenth lens L10 and the eleventh lens L11 form a cemented doublet lens group.

[0152] The imaging system may also include an aperture stop STO, which may be positioned between the thirteenth lens L13 of the lens group 10 and the imaging lens 20. Light from the object passes sequentially through the first lens L1 to the thirteenth lens L13 of the lens group 10 and each lens of the imaging lens 20, and is finally imaged on the imaging plane IMA.

[0153] The first lens L1 to the thirteenth lens L13 of the lens group 10 are all made of glass.

[0154] Table 3 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of each lens in the lens group 10 of Embodiment 3, wherein the units of radius of curvature and thickness / distance are millimeters (mm).

[0155] Table 3

[0156]

[0157] In this embodiment, when adapted to an imaging lens with a focal length of 22.48mm, the total effective focal length f of the imaging system is -50.12mm, the distance TTL between the object side surface S1 of the first lens L1 and the aperture stop S22 on the optical axis is 130.01mm, and the maximum semi-FOV of the imaging system is 7.10°.

[0158] In this embodiment, the MTF value is above 0.2 throughout the entire field of view. The MTF curve decreases smoothly and evenly from the center to the edge of the field of view. At a spatial frequency of 230 lp / mm, the MTF curve at the center of the field of view is above 0.6, indicating that the imaging system has good imaging quality and good detail resolution. Furthermore, the transverse chromatic aberration of the longest and shortest wavelengths of the imaging system is controlled within -0.5 μm to 3 μm, indicating that the imaging system can effectively correct chromatic aberration at the edge of the field of view and the secondary spectrum of the entire image plane. At the same time, the relative illumination value of the imaging system is 71% at the maximum half-field angle, indicating that the imaging system has good relative illumination.

[0159] Figure 7 The distortion curve of the imaging system of Embodiment 3 is shown, representing the distortion magnitude corresponding to different field of view angles. It can be seen from the figure that the absolute value of the optical distortion at the edge field of view in Embodiment 3 is 0.3%. According to... Figure 7 As can be seen, the imaging system given in Example 3 has the characteristics of low distortion and can achieve good imaging quality.

[0160] Example 4

[0161] Figure 8 A schematic diagram of the structure of the lens group 10 included in the imaging system according to Embodiment 4 of this application is shown.

[0162] The following is for reference Figure 1 The imaging system includes a lens group 10, an aperture stop STO, and an imaging lens 20 arranged sequentially along the optical axis from the object side to the image side. Among them, such as... Figure 8 As shown, the lens group 10 includes, in sequence along the optical axis from the object side to the image side: first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, eighth lens L8, ninth lens L9, tenth lens L10, eleventh lens L11, twelfth lens L12, and thirteenth lens L13. The imaging system also includes an imaging plane IMA disposed on the image side of the imaging lens 20.

[0163] The first lens L1 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0164] The second lens L2 has positive optical power, and its object side S2 is convex, while its image side S3 is convex.

[0165] The third lens L3 has positive optical power, and its object side S4 is convex, while its image side S5 is convex.

[0166] The fourth lens L4 has negative optical power, with its object side S5 being concave and its image side S6 being convex.

[0167] The fifth lens L5 has positive optical power, and its object side S7 is convex, and its image side S8 is convex.

[0168] The sixth lens L6 has positive optical power, with its object side S9 being concave and its image side S10 being convex.

[0169] The seventh lens L7 has positive optical power, with its object side S11 being convex and its image side S12 being concave.

[0170] The eighth lens L8 has positive optical power, with its object side S13 being convex and its image side S14 being concave.

[0171] The ninth lens L9 has negative optical power, with its object side S14 being convex and its image side S15 being concave.

[0172] The tenth lens L10 has negative optical power, and its object side S16 is concave, as is its image side S17.

[0173] The eleventh lens L11 has positive optical power, and its object-side surface S17 is convex, as is its image-side surface S18.

[0174] The twelfth lens L12 has positive optical power, and its object side S19 is convex, and its image side S20 is convex.

[0175] The thirteenth lens L13 has positive optical power, and its object side S21 is convex, while its image side S22 is convex.

[0176] The first lens L1 and the second lens L2 form a cemented doublet lens group, the third lens L3 and the fourth lens L4 form a cemented doublet lens group, the eighth lens L8 and the ninth lens L9 form a cemented doublet lens group, and the tenth lens L10 and the eleventh lens L11 form a cemented doublet lens group.

[0177] The imaging system may also include an aperture stop STO, which may be positioned between the thirteenth lens L13 of the lens group 10 and the imaging lens 20. Light from the object passes sequentially through the first lens L1 to the thirteenth lens L13 of the lens group 10 and each lens of the imaging lens 20, and is finally imaged on the imaging plane IMA.

[0178] The first lens L1 to the thirteenth lens L13 of the lens group 10 are all made of glass.

[0179] Table 4 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of each lens in the lens group 10 of Example 4, wherein the units of radius of curvature and thickness / distance are millimeters (mm).

[0180] Table 4

[0181]

[0182]

[0183] In this embodiment, when adapted to an imaging lens with a focal length of 22.48mm, the total effective focal length f of the imaging system is -52.90mm, the distance TTL between the object side surface S1 of the first lens L1 and the aperture stop S23 on the optical axis is 141.71mm, and the maximum semi-FOV of the imaging system is 7.10°.

[0184] In this embodiment 4, the MTF value is above 0.2 throughout the entire field of view. The MTF curve decreases smoothly and evenly from the center to the edge of the field of view. At a spatial frequency of 230 lp / mm, the MTF curve of the center field of view is above 0.6, indicating that the imaging system has good imaging quality and good detail resolution. Furthermore, the transaxial chromatic aberration of the longest and shortest wavelengths of the imaging system is controlled within -2μm to 2μm, indicating that the imaging system can effectively correct the chromatic aberration of the edge field of view and the secondary spectrum of the entire image plane. At the same time, the relative illumination value of the imaging system is 55% at the maximum half field of view, indicating that the imaging system has good relative illumination.

[0185] Figure 9 The distortion curve of the imaging system of Embodiment 4 is shown, representing the distortion magnitude corresponding to different field of view angles. It can be seen from the figure that the absolute value of the optical distortion at the edge field of view in Embodiment 4 is 2%. According to... Figure 9 As can be seen, the imaging system given in Example 4 has the characteristics of low distortion and can achieve good imaging quality.

[0186] Example 5

[0187] Figure 10 A schematic diagram of the structure of the lens group 10 included in the imaging system according to Embodiment 5 of this application is shown.

[0188] The following is for reference Figure 1 The imaging system includes a lens group 10, an aperture stop STO, and an imaging lens 20 arranged sequentially along the optical axis from the object side to the image side. Among them, such as... Figure 10As shown, the lens group 10 includes, in sequence along the optical axis from the object side to the image side: first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, eighth lens L8, ninth lens L9, tenth lens L10, eleventh lens L11, twelfth lens L12, and thirteenth lens L13. The imaging system also includes an imaging plane IMA disposed on the image side of the imaging lens 20.

[0189] The first lens L1 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0190] The second lens L2 has positive optical power, with its object side S2 being convex and its image side S3 being concave.

[0191] The third lens L3 has positive optical power, and its object side S4 is convex, while its image side S5 is convex.

[0192] The fourth lens L4 has negative optical power, and its object side S5 is concave, as is its image side S6.

[0193] The fifth lens L5 has positive optical power, and its object side S7 is convex, and its image side S8 is convex.

[0194] The sixth lens L6 has positive optical power, with its object side S9 being concave and its image side S10 being convex.

[0195] The seventh lens L7 has positive optical power, with its object side S11 being convex and its image side S12 being concave.

[0196] The eighth lens L8 has positive optical power, with its object side S13 being convex and its image side S14 being concave.

[0197] The ninth lens L9 has negative optical power, with its object side S14 being convex and its image side S15 being concave.

[0198] The tenth lens L10 has negative optical power, and its object side S16 is concave, as is its image side S17.

[0199] The eleventh lens L11 has positive optical power, and its object-side surface S17 is convex, while its image-side surface S28 is convex.

[0200] The twelfth lens L12 has positive optical power, with its object side S19 being concave and its image side S20 being convex.

[0201] The thirteenth lens L13 has positive optical power, and its object side S21 is convex, while its image side S22 is convex.

[0202] The first lens L1 and the second lens L2 form a cemented doublet lens group, the third lens L3 and the fourth lens L4 form a cemented doublet lens group, the eighth lens L8 and the ninth lens L9 form a cemented doublet lens group, and the tenth lens L10 and the eleventh lens L11 form a cemented doublet lens group.

[0203] The imaging system may also include an aperture stop STO, which may be positioned between the thirteenth lens L13 of the lens group 10 and the imaging lens 20. Light from the object passes sequentially through the first lens L1 to the thirteenth lens L13 of the lens group 10 and each lens of the imaging lens 20, and is finally imaged on the imaging plane IMA.

[0204] The first lens L1 to the thirteenth lens L13 of the lens group 10 are all made of glass.

[0205] Table 5 shows the radius of curvature, thickness / distance, refractive index, and Abbe number of each lens in the lens group 10 of Embodiment 5, wherein the units of radius of curvature and thickness / distance are millimeters (mm).

[0206] Table 5

[0207]

[0208]

[0209] In this embodiment, when adapted to an imaging lens with a focal length of 22.48mm, the total effective focal length f of the imaging system is -52.92mm, the distance TTL between the object side surface S1 of the first lens L1 and the aperture stop S23 on the optical axis is 142.03mm, and the maximum semi-FOV of the imaging system is 7.10°.

[0210] In this embodiment 5, the MTF value is above 0.2 throughout the entire field of view. The MTF curve decreases smoothly and evenly from the center to the edge of the field of view. At a spatial frequency of 230 lp / mm, the MTF curve of the center field of view is above 0.6, indicating that the imaging system has good imaging quality and good detail resolution. Furthermore, the transaxial chromatic aberration of the longest and shortest wavelengths of the imaging system is controlled within -0.5 μm to 3.5 μm, indicating that the imaging system can effectively correct the chromatic aberration of the edge field of view and the secondary spectrum of the entire image plane. At the same time, the relative illumination value of the imaging system is 55% at the maximum half field of view, indicating that the imaging system has good relative illumination.

[0211] Figure 11 The distortion curve of the imaging system of Embodiment 5 is shown, representing the distortion magnitude corresponding to different field of view angles. It can be seen from the figure that the absolute value of the optical distortion at the edge field of view in Embodiment 4 is 1.7%. According to... Figure 11As can be seen, the imaging system given in Example 5 has the characteristics of low distortion and can achieve good imaging quality.

[0212] In summary, Examples 1 to 5 satisfy the relationships shown in Table 6 below.

[0213] Table 6

[0214]

[0215]

[0216] This application also provides an electronic device that may include any of the imaging systems described in the above embodiments of this application. The electronic device provided in this application may be an image acquisition device, used as an imaging element to convert an optical image formed by the imaging system into an electrical signal.

[0217] 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, characterized by, In order from the object side to the image side along the optical axis, the imaging system comprises, in sequence: a first lens having optical power, a second lens having positive optical power, a third lens having optical power, a fourth lens having optical power, a fifth lens having positive optical power, a sixth lens having optical power, a seventh lens having positive optical power, an eighth lens having positive optical power, a ninth lens having negative optical power, a tenth lens having negative optical power, an eleventh lens having positive optical power, a twelfth lens having positive optical power, and a thirteenth lens having positive optical power; wherein the first lens and the third lens have opposite signs of optical power, the third lens and the fourth lens have opposite signs of optical power, and the number of lenses having optical power in the imaging system is thirteen; and the imaging system satisfies 1.1≤fd1 / f≤1.8, where fd1 is the combined effective focal length of the eighth lens and the ninth lens, and f is the effective focal length of the imaging system.

2. The imaging system of claim 1, wherein: the object side surface of the first lens is convex; the object side surface of the second lens is convex; the object side surface of the third lens is concave, and the image side surface of the third lens is concave; or the object side surface of the third lens is convex, and the image side surface of the third lens is convex; the object side surface of the fourth lens is convex or concave; the object side surface of the fifth lens is convex or concave, and the image side surface of the fifth lens is convex; the object side surface of the sixth lens is convex, and the image side surface of the sixth lens is concave; or the object side surface of the sixth lens is concave, and the image side surface of the sixth lens is convex; the object side surface of the seventh lens is convex; the object side surface of the eighth lens is convex, and the image side surface of the eighth lens is concave; the object side surface of the ninth lens is convex, and the image side surface of the ninth lens is concave; the object side surface and the image side surface of the tenth lens are both concave; the object side surface and the image side surface of the eleventh lens are both convex; the image side surface of the twelfth lens is convex; the object side surface and the image side surface of the thirteenth lens are both convex.

3. The imaging system of any of claims 1-2, wherein, The imaging system satisfies 0.08≤f9 / f≤0.24, where f9 is the effective focal length of the ninth lens, and f is the effective focal length of the imaging system.

4. The imaging system of any of claims 1-2, wherein, The imaging system satisfies at least one of the following conditional expressions: 0.14≤f10 / f≤0.32, -0.45≤f11 / f≤-0.32, where f10 is the effective focal length of the tenth lens, f11 is the effective focal length of the eleventh lens, and f is the effective focal length of the imaging system.

5. The imaging system of any of claims 1-2, wherein, The imaging system satisfies -1.35≤f13 / f≤-0.7, where f13 is the effective focal length of the thirteenth lens, and f is the effective focal length of the imaging system.

6. The imaging system of any of claims 1-2, wherein, The imaging system satisfies 2.15≤fa / fb≤2.5, where fa is the combined effective focal length of the first lens to the ninth lens, and fb is the combined effective focal length of the tenth lens to the thirteenth lens.

7. The imaging system of any of claims 1-2, wherein, The imaging system further includes a diaphragm on the image side of the thirteenth lens, the diaphragm being disposed between the image side surface of the thirteenth lens and the imaging lens, the imaging lens including a plurality of lenses, and the imaging system satisfies at least one of the following conditional expressions: 0.15 ≤ Thb / TTa ≤ 0.4, 0.15 ≤ Et / TTa ≤ 0.25, 1.9 ≤ D1 / Ed ≤ 2.5, where Thb is the on-axis distance from the object side surface of the tenth lens to the image side surface of the thirteenth lens, TTa is the on-axis distance from the object side surface of the first lens to the image side surface of the thirteenth lens, Et is the on-axis distance from the image side surface of the thirteenth lens to the diaphragm, and D1 is the optical full aperture of the object side surface of the first lens, and Ed is the light passing full aperture of the diaphragm.

8. The imaging system of any of claims 1-2, wherein, The imaging system satisfies at least one of the following conditional expressions: -1.80 ≤ f1 / f ≤ 1.42, -1.40 ≤ f2 / f ≤ -0.7, -1.1 ≤ f3 / f ≤ 0.42, -1 ≤ f4 / f ≤ 0.89, -3.8 ≤ f5 / f ≤ -1.15, 0.4 ≤ |f6 / f| ≤ 9, -1.7 ≤ f7 / f ≤ -0.25, -0.76 ≤ f12 / f ≤ -0.38, where f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, f7 is the effective focal length of the seventh lens, f12 is the effective focal length of the twelfth lens, and f is the effective focal length of the imaging system.

9. The imaging system of any of claims 1-2, wherein, The imaging system satisfies at least one of the following conditional expressions: 25 ≤ vd3 ≤ 95.2, 18 ≤ vd5 ≤ 95.2, 18 ≤ vd7 ≤ 35, 55 ≤ vd13 ≤ 95.2, where vd3 is the Abbe number of the third lens, vd5 is the Abbe number of the fifth lens, vd7 is the Abbe number of the seventh lens, and vd13 is the Abbe number of the thirteenth lens.

10. The imaging system according to any one of claims 1 to 2, the imaging system satisfying at least one of the following conditional expressions: -1.68 ≤ f1 / f ≤ 1.34, -1.32 ≤ f2 / f ≤ -0.73, -1.05 ≤ f3 / f ≤ 0.4, -0.95 ≤ f4 / f ≤ 0.85, -3.57 ≤ f5 / f ≤ -1.22, 0.45 ≤ |f6 / f| ≤ 8.75, -1.63 ≤ f7 / f ≤ -0.3, 0.12 ≤ f9 / f ≤ 0.21, 0.17 ≤ f10 / f ≤ 0.3, -0.44 ≤ f11 / f ≤ -0.34, -0.7 ≤ f12 / f ≤ -0.4, -1.3 ≤ f13 / f ≤ -0.72, 1.13 ≤ fd1 / f ≤ 1.75, 2.18 ≤ fa / fb ≤ 2.4, 0.19 ≤ Thb / TTa ≤ 0.35, 29 ≤ vd3 ≤ 82, 22 ≤ vd5 ≤ 82, 20 ≤ vd7 ≤ 30, 63 ≤ vd13 ≤ 95.2, wherein f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, f7 is the effective focal length of the seventh lens, f9 is the effective focal length of the ninth lens, f10 is the effective focal length of the tenth lens, f11 is the effective focal length of the eleventh lens, f12 is the effective focal length of the twelfth lens, f13 is the effective focal length of the thirteenth lens, f is the effective focal length of the imaging system, fd1 is the combined effective focal length of the eighth and ninth lenses, fa is the combined effective focal length of the first through ninth lenses, fb is the combined effective focal length of the tenth through thirteenth lenses, Thb is the on-axis distance from the object side of the tenth lens to the image side of the thirteenth lens, TTa is the on-axis distance from the object side of the first lens to the image side of the thirteenth lens, vd3 is the Abbe number of the third lens, vd5 is the Abbe number of the fifth lens, vd7 is the Abbe number of the seventh lens, vd13 is the Abbe number of the thirteenth lens.

Images