Large-aperture lens

Abstract

The embodiment of the utility model discloses a large-aperture lens. The large-aperture lens comprises a first lens, a second lens, a diaphragm, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens which are sequentially arranged from an object side to an image side along an optical axis, one glass spherical lens and seven plastic aspheric lenses are adopted, the specific surface type of each lens is limited, and the matching of the focal power and the surface type is utilized, so that good aberration correction, distortion reduction and large aperture are realized, enough good image quality is ensured, a 1 / 1.8 inch chip can be matched, the requirements of large aperture, low distortion and high resolution are met, and the requirements of large aperture, low distortion and high resolution are met. According to the utility model, the large-aperture lens with the focal length of 8mm, the total length of 22.5 mm, the imaging requirement and low distortion can be realized, the cost is low, and the large-aperture lens with the focal length of 8mm and the total length of 22.5 mm can be designed.

Description

Technical Field

[0001] This utility model relates to the field of optical lens technology, and in particular to a large aperture lens. Background Technology

[0002] With the increasing prevalence of security monitoring facilities, the market demands higher and higher quality security monitoring lenses. Fixed-focus lenses, as the mainstream product in the security industry, are very popular. However, current fixed-focus lenses are too long overall and have insufficient aperture, making them unsuitable for 1 / 1.8″ sensor chips. Their overall performance cannot meet the requirements of the sensors used. Utility Model Content

[0003] This invention provides a large aperture lens to achieve a low-cost large aperture lens design that balances imaging requirements and a compact structure.

[0004] In a first aspect, this utility model embodiment provides a large aperture lens, including a first lens, a second lens, an aperture stop, 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;

[0005] The first lens is an aspherical plastic lens with negative optical power, and is a convex-concave lens with a convex surface facing the object side and a concave surface facing the image side.

[0006] The second lens is an aspherical plastic lens with negative optical power, and is a concave-convex lens with a concave surface facing the object side and a convex surface facing the image side.

[0007] The third lens is an aspherical plastic lens with positive optical power, and is a central convex-central concave lens with a convex central area on the object side and a concave central area on the image side.

[0008] The fourth lens is a glass spherical lens with positive optical power, and is a plano-convex lens with a flat surface facing the object side and a convex surface facing the image side.

[0009] The fifth lens is an aspherical plastic lens with positive optical power, and is a biconvex lens with a convex surface on the object side and a convex surface on the image side.

[0010] The sixth lens is an aspherical plastic lens with negative optical power, and is a biconcave lens with a concave surface on both the object side and the image side.

[0011] The seventh lens is an aspherical plastic lens with positive optical power, and is a concave-convex central lens with a concave central region on the object side and a concave central region on the image side.

[0012] The eighth lens is an aspherical plastic lens with negative optical power, and is a central convex-central concave lens with a convex central region on the object side and a concave central region on the image side.

[0013] Optionally, the first lens to the eighth lens satisfy the following condition:

[0014] |V3-V5|≥17.0;

[0015] V4+V5+V6+V7≤175.0;

[0016] V3+V5+V7≤135.0;

[0017] V2+V3+V4+V5≤175.0;

[0018] |V1-V8|≤36.0;

[0019] Wherein, V1-V8 are the Abbe numbers of the first lens to the eighth lens, respectively.

[0020] Optionally, the large aperture lens satisfies the following conditions:

[0021] TTL≤22.4;

[0022] AAG / BFL ≥ 0.85;

[0023] (EFL+BFL) / Fno≥10.0;

[0024] ImgH / BFL ≥ 0.9;

[0025] HFOV / TTL≤1.70;

[0026] Wherein, TTL is the distance from the object side of the first lens to the imaging plane, AAG is the total air gap between the first lens and the eighth lens, BFL is the distance from the image side of the eighth lens to the image focal point, EFL is the focal length of the large aperture lens, Fno is the aperture coefficient of the large aperture lens, ImgH is the half image height, and HFOV is the half field of view.

[0027] Optionally, the large aperture lens satisfies the following conditions:

[0028] ALT / (T2+BFL)≥2.0;

[0029] ALT / (T1+G12)≤4.5;

[0030] ALT / (G23+G78)≤145.0;

[0031] Wherein, ALT is the total center thickness of the first lens to the eighth lens, BFL is the distance from the image side of the eighth lens to the image focal point, T1 is the center thickness of the first lens, T2 is the center thickness of the second lens, G12 is the air gap between the center of the first lens and the center of the second lens, G23 is the air gap between the center of the second lens and the center of the third lens, and G78 is the air gap between the center of the seventh lens and the center of the eighth lens.

[0032] Optionally, the large aperture lens satisfies the following condition: AAG / (T3+G45)≤2.90;

[0033] Wherein, AAG is the total air gap between the first lens and the eighth lens, T3 is the center thickness of the third lens, and G45 is the air gap between the center of the fourth lens and the center of the fifth lens.

[0034] Optionally, the large aperture lens satisfies the following condition: HFOV / (T6+T7+T8)≤8.0;

[0035] Wherein, HFOV is the half field of view, T6 is the center thickness of the sixth lens, T7 is the center thickness of the seventh lens, and T8 is the center thickness of the eighth lens.

[0036] Optionally, the large aperture lens satisfies the following conditions:

[0037] (G45+G78+EFL) / (T3+T5)≥1.9;

[0038] EFL / (G12+T2+G45)≥1.8;

[0039] Wherein, EFL is the focal length of the large aperture lens, G12 is the air gap between the center of the first lens and the center of the second lens, G45 is the air gap between the center of the fourth lens and the center of the fifth lens, G78 is the air gap between the center of the seventh lens and the center of the eighth lens, T2 is the center thickness of the second lens, T3 is the center thickness of the third lens, and T5 is the center thickness of the fifth lens.

[0040] Optionally, the large aperture lens satisfies the following conditions:

[0041] TL / (G23+T3+G34+T4)≥3.5;

[0042] TL / (G23+G34+T4)≤9.0;

[0043] Where TL is the sum of AAG and ALT, AAG is the total air gap between the first lens and the eighth lens, and ALT is the total center thickness between the first lens and the eighth lens.

[0044] Optionally, the large aperture lens satisfies the following conditions:

[0045] (T1+T8) / T3≥0.8;

[0046] (T3+T6) / T8≤3.00;

[0047] Wherein, T1 is the center thickness of the first lens, T3 is the center thickness of the third lens, T6 is the center thickness of the sixth lens, and T8 is the center thickness of the third lens.

[0048] Optionally, the large aperture lens satisfies the following conditions:

[0049] (T7+G78+T8) / (G45+T5+G67)≥0.8;

[0050] (T1+G23) / (G12+G78)≥0.3;

[0051] G78 / (T2+T4)≥0.35;

[0052] (G45+T5+G67) / T8≤3.0;

[0053] Wherein, T1 is the center thickness of the first lens, T2 is the center thickness of the second lens, T4 is the center thickness of the fourth lens, T5 is the center thickness of the fifth lens, T7 is the center thickness of the seventh lens, and T8 is the center thickness of the third lens; G12 is the air gap between the center of the first lens and the center of the second lens, G23 is the air gap between the center of the second lens and the center of the third lens, G45 is the air gap between the center of the fourth lens and the center of the fifth lens, G67 is the air gap between the center of the sixth lens and the center of the seventh lens, and G78 is the air gap between the center of the seventh lens and the center of the eighth lens.

[0054] In this embodiment of the invention, a glass spherical lens and seven plastic aspherical lenses are used. Specifically, these are the first, second, third, fourth, fifth, sixth, seventh, and eighth lenses, arranged sequentially along the optical axis from the object side to the image side, with optical powers of negative negative positive positive positive positive negative positive negative and negative respectively. Each lens has its own specific surface shape. By combining optical power and surface shape, aberration correction and distortion reduction are achieved. Sufficient image quality is maintained while maintaining a large aperture. It can be paired with a 1 / 1.8-inch chip to achieve the requirements of large aperture, low distortion, and high resolution, while maintaining good image quality at the working distance. Ultimately, a low-cost, large-aperture lens design with a focal length of 8mm and a total length of 22.5mm is achieved, which takes into account imaging requirements and low distortion. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the structure of a large aperture lens provided in Embodiment 1 of this utility model;

[0056] Figure 2 yes Figure 1 The spherical aberration curve of a large aperture lens is shown.

[0057] Figure 3 yes Figure 1 The field curvature distortion diagram of the large aperture lens is shown.

[0058] Figure 4 yes Figure 1 The chromatic aberration curve of a large aperture lens is shown.

[0059] Figure 5 This is a schematic diagram of the structure of a large aperture lens provided in Embodiment 2 of this utility model;

[0060] Figure 6 yes Figure 5 The spherical aberration curve of a large aperture lens is shown.

[0061] Figure 7 yes Figure 5 The field curvature distortion diagram of the large aperture lens is shown.

[0062] Figure 8 yes Figure 5 The chromatic aberration curve of a large aperture lens is shown.

[0063] Figure 9 This is a schematic diagram of the structure of a large aperture lens provided in Embodiment 3 of this utility model;

[0064] Figure 10 yes Figure 9 The spherical aberration curve of a large aperture lens is shown.

[0065] Figure 11 yes Figure 9The field curvature distortion diagram of the large aperture lens is shown.

[0066] Figure 12 yes Figure 9 The chromatic aberration curve of the large aperture lens is shown. Detailed Implementation

[0067] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0068] Figure 1 This is a schematic diagram of the structure of a large aperture lens provided in Embodiment 1 of this utility model, for reference. Figure 1 The large-aperture lens includes a first lens 10, a second lens 20, an aperture stop STO, a third lens 30, a fourth lens 40, a fifth lens 50, a sixth lens 60, a seventh lens 70, and an eighth lens 80 arranged sequentially along the optical axis from the object side to the image side. The first lens 10 is an aspherical plastic lens with negative optical power, and is a convex-concave lens with a convex surface facing the object side and a concave surface facing the image side. The second lens 20 is an aspherical plastic lens with negative optical power, and is a concave-convex lens with a concave surface facing the object side and a convex surface facing the image side. The third lens 30 is an aspherical plastic lens with positive optical power, and is a centrally convex-centrally concave lens with a convex central area facing the object side and a concave central area facing the image side. The fourth lens 40 is a positive... The first lens is a glass spherical lens with optical power, and is a plano-convex lens with a flat surface facing the object side and a convex surface facing the image side; the second lens is a positive optical power aspherical plastic lens, and is a biconvex lens with a convex surface facing both the object and image sides; the third lens is a negative optical power aspherical plastic lens, and is a biconcave lens with a concave surface facing both the object and image sides; the fourth lens is a positive optical power aspherical plastic lens, and is a central concave-convex lens with a concave central area facing both the object and image sides; the fifth lens is a positive optical power aspherical plastic lens, and is a central convex-central concave lens with a convex central area facing both the object and image sides.

[0069] First, for optical lenses, optical power equals the difference between the image-side beam convergence and the object-side beam convergence; it characterizes the optical system's ability to deflect light. The larger the absolute value of optical power, the stronger the bending ability of light; the smaller the absolute value, the weaker the bending ability. When optical power is positive, the refraction of light is converging; when optical power is negative, the refraction of light is diverging. Optical power can be used to characterize a single refractive surface of a lens (i.e., one surface of the lens), a single lens, or a system formed by multiple lenses (i.e., a lens group).

[0070] In the large aperture lens provided in this embodiment, all lenses can be housed in a single lens barrel. Figure 1 (not shown in the image) such as Figure 1 As shown in this embodiment of the invention, a fixed-focus lens is formed by setting eight lenses. The optical power of these eight lenses works in coordination to achieve a fixed-focus lens design that meets the requirements of a large aperture, compact structure, and robust imaging. Specifically, the combination of the surface shapes of the lenses not only allows for a reasonable allocation of optical power but also effectively saves space and expands the lens's application scenarios.

[0071] The first lens 10 has a meniscus structure, meaning it is a convex-concave lens with a convex surface facing the object side and a concave surface facing the image side. The convexity on the object side helps to converge light rays, allowing light with a wider field of view to enter the imaging system, thus meeting the field of view requirements. Furthermore, the first lens 10 uses negative optical power, forming a symmetrical optical system with the eighth lens 80, which also has negative optical power, thereby shortening the overall lens length.

[0072] The first lens 10 and the second lens 20, with negative optical power, are located before the aperture stop STO, ensuring a wider field of view for light before it enters the STO. The aperture stop STO, positioned between the second lens 20 and the third lens 30, limits the propagation angle of light, adjusts the incident angle, and filters out off-axis rays, reducing chromatic aberration. The third lens 30, a centrally concave-centrally convex aspherical plastic, and the fourth lens 40, a plano-convex glass spherical lens, both with positive optical power, further converge the light passing through the aperture stop STO. Together, they allow light to propagate smoothly before and after the STO. These two lenses are positioned immediately after the aperture stop STO. The aspherical third lens 30 corrects the image quality of light after the STO, while the glass fourth lens 40 stabilizes the image quality's sensitivity to temperature, ensuring stable lens performance at high and low temperatures. Therefore, their central position, which significantly impacts image quality, ensures both image quality and stability.

[0073] Furthermore, the fifth lens 50 (positive power), the sixth lens 60 (negative power), and the seventh lens 70 (positive power) can be combined to form a positive power lens group, which is responsible for further converging the light after passing through the aperture stop (STO). The fifth lens 50 is biconvex, the sixth lens 60 is biconcave, and the seventh lens 70 is centrally concave-convex, i.e., three aspherical surfaces. Utilizing different surface structures, each can correct aberrations individually during the smoothing of the light propagation path. The eighth lens 80, with negative power, is responsible for diffusing light. Simultaneously, using an aspherical lens, it can eliminate residual higher-order aberrations of the lens, expanding the target area while improving image quality. Ultimately, through the 1G7P system (one glass lens and seven plastic lenses), excellent aberration correction and distortion reduction are achieved, ensuring sufficiently good image quality at a large aperture. It can be paired with a 1 / 1.8-inch sensor.

[0074] In an optional embodiment, the first lens 10 to the eighth lens 80 satisfy the following condition:

[0075] |V3-V5|≥17.0;

[0076] V4+V5+V6+V7≤175.0;

[0077] V3+V5+V7≤135.0;

[0078] V2+V3+V4+V5≤175.0;

[0079] |V1-V8|≤36.0;

[0080] Among them, V1-V8 are the Abbe numbers of the first lens 10 to the eighth lens 80, respectively.

[0081] Specifically, by limiting the Abbe number of each lens, especially the Abbe number of the third lens 30 and the fifth lens 50, which are located in the middle of the entire lens and immediately after the aperture stop STO, chromatic aberration can be better corrected, resulting in better image quality.

[0082] In one alternative embodiment, the large aperture lens satisfies the following condition:

[0083] TTL≤22.4;

[0084] AAG / BFL ≥ 0.85;

[0085] (EFL+BFL) / Fno≥10.0;

[0086] ImgH / BFL ≥ 0.9;

[0087] HFOV / TTL≤1.70;

[0088] Where TTL is the distance from the object side of the first lens 10 to the image plane, AAG is the total air gap between the first lens 10 and the eighth lens 80, BFL is the distance from the image side of the eighth lens 80 to the image focal point, EFL is the focal length of the large aperture lens, Fno is the aperture coefficient of the large aperture lens, ImgH is the half image height, and HFOV is the half field of view.

[0089] Specifically, the above conditions limit the size of the lens along the optical axis by restricting various dimensions or distance ranges of the lens, such as total length, air gap, and back focal length. Furthermore, while limiting the lens to have a small aperture (i.e., a small aperture coefficient), the above conditions also ensure a small size along the optical axis. Thus, while achieving a large aperture, it is possible to achieve the smallest possible aperture and length, thereby achieving a smaller lens volume and contributing to miniaturization.

[0090] In one alternative embodiment, the large aperture lens satisfies the following condition:

[0091] ALT / (T2+BFL)≥2.0;

[0092] ALT / (T1+G12)≤4.5;

[0093] ALT / (G23+G78)≤145.0;

[0094] Wherein, ALT is the total center thickness of the first lens 10 to the eighth lens 80, BFL is the distance from the image side of the eighth lens 80 to the image focal point, T1 is the center thickness of the first lens 10, T2 is the center thickness of the second lens 20, G12 is the air gap between the center of the first lens 10 and the center of the second lens 20, G23 is the air gap between the center of the second lens 20 and the center of the third lens 30, and G78 is the air gap between the center of the seventh lens 70 and the center of the eighth lens 80.

[0095] Specifically, the above conditions essentially restrict the thickness and spacing of a specific lens, such as the second lens 20, from the perspective of lens thickness. This can increase the thickness of the specific lens, avoid making the lens too thin and thus increasing the difficulty of manufacturing, and facilitate the manufacturing of the specific lens. At the same time, by adjusting the spacing between the specific lenses, different lens placement positions can be provided, thereby enabling the lenses to be directly fitted and assembled, or to form a sufficiently large spacing, ultimately achieving the effect of easy manufacturing and assembly.

[0096] In an optional embodiment, the large aperture lens satisfies the following condition: AAG / (T3+G45)≤2.90; where AAG is the sum of the air gaps between the first lens 10 and the eighth lens 80, T3 is the center thickness of the third lens 30, and G45 is the air gap between the center of the fourth lens 40 and the center of the fifth lens 50.

[0097] Specifically, the above conditions essentially limit the thickness of a specific lens, such as the third lens 30, and the spacing between the fourth lens 40 and the fifth lens 50 from the perspective of air gap. Similarly, this can increase the thickness of the third lens, avoid making the lens too thin and increasing the difficulty of manufacturing, and facilitate the manufacturing of the third lens; at the same time, increasing the spacing between the fourth lens 40 and the fifth lens 50 can provide sufficient assembly space between the lenses, making assembly convenient.

[0098] In an optional embodiment, the large aperture lens satisfies the following condition: HFOV / (T6+T7+T8)≤8.0; where HFOV is the half field of view, T6 is the center thickness of the sixth lens 60, T7 is the center thickness of the seventh lens 70, and T8 is the center thickness of the eighth lens 80.

[0099] Specifically, the above conditions are essentially the angle of image height, which limits the thickness of specific lenses, namely the sixth lens 60, the seventh lens 70, and the eighth lens 80. Similarly, this can increase the thickness of the three lenses, avoid making the lenses too thin and increasing the difficulty of manufacturing them, and facilitate the manufacturing of the three lenses.

[0100] In one alternative embodiment, the large aperture lens satisfies the following condition:

[0101] (G45+G78+EFL) / (T3+T5)≥1.9;

[0102] EFL / (G12+T2+G45)≥1.8;

[0103] Wherein, EFL is the focal length of the large aperture lens, G12 is the air gap between the center of the first lens 10 and the center of the second lens 20, G45 is the air gap between the center of the fourth lens 40 and the center of the fifth lens 50, G78 is the air gap between the center of the seventh lens 70 and the center of the eighth lens 80, T2 is the center thickness of the second lens 20, T3 is the center thickness of the third lens 30, and T5 is the center thickness of the fifth lens 50.

[0104] Specifically, the above conditions essentially restrict the thickness and spacing of a specific lens, such as the second lens 20, from the perspective of focal length. Similarly, this can increase the thickness of the specific lens, avoid making the lens too thin and increasing the difficulty of manufacturing, and facilitate the manufacturing of the specific lens. At the same time, by adjusting the spacing between the specific lenses, different lens placement positions can be provided, thereby enabling the lenses to be directly fitted and assembled, or to form a sufficiently large spacing, ultimately achieving the effect of easy manufacturing and assembly.

[0105] In one alternative embodiment, the large aperture lens satisfies the following condition:

[0106] TL / (G23+T3+G34+T4)≥3.5;

[0107] TL / (G23+G34+T4)≤9.0;

[0108] Where TL is the sum of AAG and ALT, AAG is the total air gap between the first lens 10 and the eighth lens 80, and ALT is the total center thickness of the first lens 10 to the eighth lens 80.

[0109] Specifically, the above conditions essentially restrict the thickness and spacing of specific lenses, such as the second lens 20 to the fourth lens 40, from the perspective of the total length of all lenses in the optical axis direction. Similarly, this allows for the increase of the thickness of specific lenses while ensuring a small overall volume, avoiding the increased difficulty in manufacturing excessively thin lenses and facilitating the manufacturing of specific lenses. At the same time, the relative positions of the three lenses are reasonably arranged to provide sufficient assembly space, ultimately achieving the effect of easy manufacturing and assembly.

[0110] In one alternative embodiment, the large aperture lens satisfies the following condition:

[0111] (T1+T8) / T3≥0.8;

[0112] (T3+T6) / T8≤3.00;

[0113] Wherein, T1 is the center thickness of the first lens 10, T3 is the center thickness of the third lens 30, T6 is the center thickness of the sixth lens 60, and T8 is the center thickness of the third lens 30.

[0114] Specifically, the above conditions are essentially from the perspective of the relationship between specific lenses, limiting the thickness of specific lenses, such as the third lens 30 to the eighth lens 80. Similarly, this can increase the thickness of specific lenses, avoid making the lens too thin and increasing the difficulty of manufacturing, and facilitate the manufacturing of specific lenses.

[0115] In one alternative embodiment, the large aperture lens satisfies the following condition:

[0116] (T7+G78+T8) / (G45+T5+G67)≥0.8;

[0117] (T1+G23) / (G12+G78)≥0.3;

[0118] G78 / (T2+T4)≥0.35;

[0119] (G45+T5+G67) / T8≤3.0;

[0120] Wherein, T1 is the center thickness of the first lens 10, T2 is the center thickness of the second lens 20, T4 is the center thickness of the fourth lens 40, T5 is the center thickness of the fifth lens 50, T7 is the center thickness of the seventh lens 70, and T8 is the center thickness of the third lens 30; G12 is the air gap between the center of the first lens 10 and the center of the second lens 20, G23 is the air gap between the center of the second lens 20 and the center of the third lens 30, G45 is the air gap between the center of the fourth lens 40 and the center of the fifth lens 50, G67 is the air gap between the center of the sixth lens 60 and the center of the seventh lens 70, and G78 is the air gap between the center of the seventh lens 70 and the center of the eighth lens 80.

[0121] Specifically, the above conditions essentially restrict the thickness and spacing of a specific lens from the perspective of the relationship between the thickness of each lens and the air gap. Similarly, this can increase the thickness of a specific lens, avoid making the lens too thin and increasing the difficulty of manufacturing, and facilitate the manufacturing of a specific lens. At the same time, the relative positions of the specific lenses are arranged reasonably to provide sufficient assembly space, ultimately achieving the effect of easy manufacturing and easy assembly.

[0122] In summary, this embodiment of the invention, by using a combination of 8 lenses (1G7P), can effectively correct aberrations and reduce distortion, while maintaining sufficient image quality at a large aperture. It can be paired with a 1 / 1.8-inch chip to achieve the requirements of large aperture, low distortion, and high resolution, and maintain good image quality at the working distance. Ultimately, it achieves a low-cost, large-aperture lens design with a focal length of 8mm and a total length of 22.5mm, which takes into account both imaging requirements and low distortion.

[0123] Based on the same concept, this utility model provides three different specific embodiments, and their optical power relationship and related physical optical parameter design ranges are shown in Table 1:

[0124] Table 1. Relevant physical and optical parameters in each embodiment.

[0125]

[0126]

[0127]

[0128] In Embodiment 1 of this utility model, reference is made to... Figure 1The structure, shape, and location of each component in the system are known, which is crucial for the system's performance. As shown in the figure, the optical system consists of eight optical lenses, with the aperture stop STO located between the second lens 20 and the third lens 30. A filter 90 is also positioned along the object plane to the image plane; the filter 90 is located on the image-side surface of the eighth lens 80 and protects the image sensor chip, ensuring the lens's imaging performance. This large-aperture lens has a focal length f of 7.870mm, an f / 1.08 aperture, and a total length of 20.08mm. The optimal working object distance for this system is infinity.

[0129] like Figure 1 The parameter design values ​​of each lens in the large aperture lens of Embodiment 1 are shown in Table 2:

[0130] Table 2 shows a design value for each lens in the large aperture lens of Example 1.

[0131]

[0132]

[0133] The surface numbers in Table 2 are assigned according to the surface sequence of each lens. "STO" represents the aperture stop STO of this large-aperture lens; the radius of curvature represents the curvature of the lens surface, with positive values ​​indicating that the surface bends towards the image plane and negative values ​​indicating that the surface bends towards the object plane. "Infinity" indicates that the surface is flat and has an infinite radius of curvature; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light; a blank space indicates that the current position is air and the refractive index is 1. S17 represents a filter.

[0134] The aspherical lenses in Table 2 satisfy the following formula:

[0135]

[0136] Where: z is the distance sag of the aspherical lens from the vertex of the aspherical lens at a position of height y along the optical axis, c = 1 / R, R represents the radius of curvature of the center of the aspherical lens surface, k represents the conic coefficient, and parameters A, B, C, D, E, F, and G are higher-order aspherical coefficients.

[0137] The coefficient values ​​of each aspherical surface in the above embodiment 1 are shown in Table 3:

[0138] Table 3 Aspheric coefficients of the lenses in Example 1

[0139] Face number K A B C D E F G S1 -5.15E+00 2.71E-03 -6.54E-04 3.79E-05 -6.56E-07 -2.14E-08 8.71E-10 -4.76E-12 S2 -2.48E+00 3.11E-04 -1.72E-04 -3.17E-05 5.04E-06 -2.63E-07 3.81E-09 3.12E-11 S3 -3.81E+00 4.31E-03 -5.54E-04 1.96E-05 -8.97E-08 1.23E-07 -1.71E-08 5.47E-10 S4 4.15E+00 -1.03E-03 7.25E-04 -2.15E-04 3.03E-05 -2.25E-06 8.33E-08 -1.21E-09 S5 -3.08E+01 -2.42E-03 -1.12E-04 -1.76E-06 1.85E-06 -1.72E-07 3.27E-09 6.18E-11 S6 -3.60E+00 -4.71E-03 1.59E-04 -2.23E-06 -9.01E-08 -7.18E-09 7.35E-10 -1.30E-11 S9 -7.73E+00 2.68E-03 -4.28E-04 7.77E-06 1.67E-06 -1.33E-07 3.51E-09 -1.91E-11 S10 -1.00E+02 -9.50E-04 -1.99E-05 1.09E-06 4.70E-07 -3.97E-08 9.96E-10 3.27E-12 S11 6.74E+01 1.94E-03 9.67E-05 -2.11E-05 6.49E-07 4.55E-08 -2.88E-09 4.30E-11 S12 -6.48E+00 3.43E-03 1.80E-04 -6.37E-05 4.79E-06 -1.32E-07 8.40E-10 9.16E-13 S13 -1.32E+02 -1.49E-03 4.90E-04 -3.30E-05 9.63E-07 1.54E-08 -1.00E-09 -3.45E-12 S14 -3.91E+00 -1.75E-03 2.28E-04 -1.91E-05 7.69E-07 9.66E-09 -1.97E-09 4.81E-11 S15 -1.53E+00 -4.59E-03 4.83E-04 -4.91E-05 2.20E-06 1.84E-08 -5.89E-09 1.56E-10 S16 -5.67E+00 -1.86E-03 1.14E-04 -9.88E-06 3.78E-07 -5.50E-09 -2.82E-10 1.09E-11

[0140] Where 2.71E-03 indicates that the coefficient A of surface number S1 is 2.71 * 10. -3 And so on.

[0141] Figure 2 yes Figure 1 The spherical aberration curve of the large aperture lens shown is for reference. Figure 2 In the figure, the vertical direction represents the normalized aperture, 0 indicates being on the optical axis, and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of system imaging, determined by... Figure 2 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.2mm, +0.2mm), indicating that the spherical aberration of this large aperture lens is well controlled at each wavelength, which can meet the requirements of wide spectrum applications.

[0142] Figure 3 yes Figure 1 The field curvature distortion diagram of the large aperture lens shown is for reference. Figure 3 In the coordinate system on the left side of the figure, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the arc loss; from Figure 3 As can be seen, the lens provided in this embodiment effectively controls the field curvature from light with wavelengths of 436nm to 656nm, meaning that during imaging, the difference between the image quality at the center and the image quality at the periphery is small; in the coordinate system on the right, the horizontal coordinate represents the magnitude of distortion in %; the vertical coordinate represents the normalized image height, which has no unit.

[0143] Figure 4 yes Figure 1 The chromatic aberration curve of the large aperture lens shown is for reference. Figure 4 The vertical direction represents the image height in mm; the horizontal direction represents the offset of different wavelengths from the optical axis at the image plane after passing through the system, in micrometers (μm). Different linear curves in the figure represent different wavelengths imaged by the system; the curves in the vertical direction on both sides of the figure are Airy disks.

[0144] Figure 5 This is a schematic diagram of the structure of a large aperture lens provided in Embodiment 2 of this utility model. In Embodiment 2 of this utility model, reference is made to... Figure 5The optical system consists of eight optical lenses, with the aperture stop STO located between the second lens 20 and the third lens 30. A filter 90 is also positioned along the object plane to the image plane; the filter 90 is located on the image-side surface of the eighth lens 80 and protects the image sensor chip to ensure the lens's imaging performance. This large-aperture lens has a focal length f = 7.814mm, an f / 1.08 aperture, and a total length of 19.62mm. The optimal working object distance for this system is infinity.

[0145] like Figure 5 The design parameters of each lens in the large aperture lens of Embodiment 2 are shown in Table 4:

[0146] Table 4 shows a design value for each lens in the large aperture lens of Example 2.

[0147]

[0148]

[0149] The surface numbers in Table 4 are assigned according to the surface sequence of each lens. "STO" represents the aperture stop STO of this large-aperture lens; the radius of curvature represents the curvature of the lens surface, with positive values ​​indicating that the surface bends towards the image plane and negative values ​​indicating that the surface bends towards the object plane. "Infinity" indicates that the surface is flat and has an infinite radius of curvature; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light; a blank space indicates that the current position is air and the refractive index is 1. S17 represents a filter.

[0150] The aspherical lenses in Table 4 satisfy the following formula:

[0151]

[0152] Where: z is the distance sag of the aspherical lens from the vertex of the aspherical lens at a position of height y along the optical axis, c = 1 / R, R represents the radius of curvature of the center of the aspherical lens surface, k represents the conic coefficient, and parameters A, B, C, D, E, F, and G are higher-order aspherical coefficients.

[0153] The coefficient values ​​of each aspherical surface in the above embodiment 2 are shown in Table 5:

[0154] Table 5 Aspheric coefficients of the lenses in Example 2

[0155] Face number K A B C D E F G S1 -6.70E+00 3.18E-03 -6.64E-04 3.73E-05 -6.63E-07 -2.06E-08 9.91E-10 -9.08E-12 S2 -2.61E+00 3.71E-04 -1.72E-04 -3.27E-05 5.01E-06 -2.62E-07 3.83E-09 4.54E-11 S3 -6.37E+00 3.78E-03 -5.89E-04 2.06E-05 -5.99E-08 1.21E-07 -1.70E-08 5.44E-10 S4 5.06E+00 -2.03E-03 7.18E-04 -2.14E-04 3.04E-05 -2.25E-06 8.30E-08 -1.21E-09 S5 -4.21E+01 -2.19E-03 -1.19E-04 8.72E-08 1.92E-06 -1.71E-07 3.24E-09 4.92E-11 S6 -3.00E+00 -4.49E-03 1.70E-04 -1.78E-06 -9.70E-08 -7.84E-09 6.92E-10 -1.21E-11 S9 -5.50E+00 3.13E-03 -4.34E-04 8.31E-06 1.70E-06 -1.35E-07 3.29E-09 -2.77E-11 S10 -5.28E+01 -1.08E-03 2.01E-05 8.16E-07 4.17E-07 -4.06E-08 9.80E-10 -1.15E-11 S11 1.48E+01 1.84E-03 1.16E-04 -1.98E-05 6.75E-07 4.29E-08 -3.05E-09 4.99E-11 S12 -7.21E+00 3.34E-03 1.74E-04 -6.44E-05 4.76E-06 -1.32E-07 8.82E-10 -7.46E-12 S13 -1.89E+03 -1.32E-03 4.68E-04 -3.35E-05 9.64E-07 1.48E-08 -9.54E-10 -9.28E-13 S14 -4.40E+00 -2.40E-03 2.37E-04 -1.79E-05 7.75E-07 7.05E-09 -1.96E-09 6.26E-11 S15 -2.44E+00 -4.56E-03 4.81E-04 -5.06E-05 2.17E-06 1.87E-08 -5.86E-09 1.63E-10 S16 -5.20E+00 -2.51E-03 1.04E-04 -1.06E-05 3.76E-07 -3.58E-09 -1.84E-10 7.56E-12

[0156] Where 3.18E-03 indicates that the coefficient A of surface number S1 is 3.18 * 10^3. -3 And so on.

[0157] Figure 6 yes Figure 5 The spherical aberration curve of the large aperture lens shown is for reference. Figure 6 In the figure, the vertical direction represents the normalized aperture, 0 indicates being on the optical axis, and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of system imaging, determined by... Figure 6 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.2mm, +0.2mm), indicating that the spherical aberration of this large aperture lens is well controlled at each wavelength, which can meet the requirements of wide spectrum applications.

[0158] Figure 7 yes Figure 5 The field curvature distortion diagram of the large aperture lens shown is for reference. Figure 7 In the coordinate system on the left side of the figure, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the arc loss; from Figure 7 As can be seen, the lens provided in this embodiment effectively controls the field curvature from light with wavelengths of 436nm to 656nm, meaning that during imaging, the difference between the image quality at the center and the image quality at the periphery is small; in the coordinate system on the right, the horizontal coordinate represents the magnitude of distortion in %; the vertical coordinate represents the normalized image height, which has no unit.

[0159] Figure 8 yes Figure 5 The chromatic aberration curve of the large aperture lens shown is for reference. Figure 8 The vertical direction represents the image height in mm; the horizontal direction represents the offset of different wavelengths from the optical axis at the image plane after passing through the system, in micrometers (μm). Different linear curves in the figure represent different wavelengths imaged by the system; the curves in the vertical direction on both sides of the figure are Airy disks.

[0160] Figure 9 This is a schematic diagram of the structure of a large aperture lens provided in Embodiment 3 of this utility model. In Embodiment 3 of this utility model, reference is made to... Figure 9 The optical system consists of eight optical lenses, with the aperture stop STO located between the second lens 20 and the third lens 30. A filter 90 is also positioned along the path from the object plane to the image plane; the filter 90 is located on the image-side surface of the eighth lens 80 and protects the image sensor chip to ensure image quality. The large-aperture lens has a focal length of 8.019mm, an f# of 1.08, and a total length of 21.24mm. The optimal working object distance for this system is infinity.

[0161] like Figure 9The parameter design values ​​of each lens in the large aperture lens of Embodiment 3 are shown in Table 6:

[0162] Table 6 shows a design value for each lens in the large aperture lens of Example 3.

[0163]

[0164]

[0165] The surface numbers in Table 6 are assigned according to the surface sequence of each lens. "STO" represents the aperture stop STO of this large-aperture lens; the radius of curvature represents the curvature of the lens surface, with positive values ​​indicating that the surface bends towards the image plane and negative values ​​indicating that the surface bends towards the object plane. "Infinity" indicates that the surface is flat and has an infinite radius of curvature; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light; a blank space indicates that the current position is air and the refractive index is 1. S17 represents a filter.

[0166] The aspherical lenses in Table 6 satisfy the following formula:

[0167]

[0168] Where: z is the distance sag of the aspherical lens from the vertex of the aspherical lens at a position of height y along the optical axis, c = 1 / R, R represents the radius of curvature of the center of the aspherical lens surface, k represents the conic coefficient, and parameters A, B, C, D, E, F, and G are higher-order aspherical coefficients.

[0169] The coefficient values ​​of each aspherical surface in the above embodiment three are shown in Table 7:

[0170] Table 7 Aspheric coefficients of the lenses in Example 3

[0171] Face number K A B C D E F G S1 -4.74E+00 3.47E-03 -6.60E-04 3.70E-05 -6.60E-07 -1.98E-08 1.01E-09 -1.05E-11 S2 -1.84E+00 4.03E-04 -1.37E-04 -3.04E-05 4.92E-06 -2.64E-07 4.19E-09 2.28E-11 S3 -1.94E+00 3.59E-03 -5.78E-04 1.84E-05 -1.22E-07 1.29E-07 -1.66E-08 5.10E-10 S4 7.69E+00 -1.86E-03 6.58E-04 -2.16E-04 3.04E-05 -2.24E-06 8.33E-08 -1.23E-09 S5 -3.07E+01 -2.04E-03 -1.33E-04 -1.24E-06 1.95E-06 -1.69E-07 3.01E-09 2.56E-11 S6 -9.78E+00 -4.89E-03 1.81E-04 -1.67E-06 -1.54E-07 -1.06E-08 6.72E-10 -5.60E-12 S9 -4.84E+00 2.18E-03 -4.03E-04 9.14E-06 1.68E-06 -1.36E-07 3.35E-09 -1.81E-11 S10 -4.18E+00 -1.15E-03 1.56E-05 8.38E-07 4.12E-07 -4.08E-08 1.02E-09 -2.20E-12 S11 2.28E+01 2.35E-03 1.10E-04 -2.09E-05 6.40E-07 4.30E-08 -2.97E-09 5.20E-11 S12 -4.32E+00 3.47E-03 1.80E-04 -6.43E-05 4.76E-06 -1.31E-07 9.95E-10 -2.52E-12 S13 -5.14E+01 -1.09E-03 4.63E-04 -3.32E-05 9.88E-07 1.52E-08 -1.00E-09 -6.94E-13 S14 -4.92E+00 -2.10E-03 2.41E-04 -1.84E-05 7.76E-07 8.09E-09 -1.99E-09 4.92E-11 S15 -3.78E+00 -5.20E-03 4.71E-04 -4.97E-05 2.17E-06 1.28E-08 -6.08E-09 1.83E-10 S16 -6.27E+00 -3.16E-03 9.05E-05 -1.01E-05 4.22E-07 -4.08E-09 -3.69E-10 1.32E-11

[0172] Where 3.47E-03 indicates that the coefficient A of surface number S1 is 3.47 * 10. -3 And so on.

[0173] Figure 10 yes Figure 9 The spherical aberration curve of the large aperture lens shown is for reference. Figure 10 In the figure, the vertical direction represents the normalized aperture, 0 indicates being on the optical axis, and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of system imaging, determined by... Figure 10It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.2mm, +0.2mm), indicating that the spherical aberration of this large aperture lens is well controlled at each wavelength, which can meet the requirements of wide spectrum applications.

[0174] Figure 11 yes Figure 9 The field curvature distortion diagram of the large aperture lens shown is for reference. Figure 11 In the coordinate system on the left side of the figure, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the arc loss; from Figure 11 As can be seen, the lens provided in this embodiment effectively controls the field curvature from light with wavelengths of 436nm to 656nm, meaning that during imaging, the difference between the image quality at the center and the image quality at the periphery is small; in the coordinate system on the right, the horizontal coordinate represents the magnitude of distortion in %; the vertical coordinate represents the normalized image height, which has no unit.

[0175] Figure 12 yes Figure 9 The chromatic aberration curve of the large aperture lens shown is for reference. Figure 12 The vertical direction represents the image height in mm; the horizontal direction represents the offset of different wavelengths from the optical axis at the image plane after passing through the system, in micrometers (μm). Different linear curves in the figure represent different wavelengths imaged by the system; the curves in the vertical direction on both sides of the figure are Airy disks.

[0176] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A large aperture lens, characterized in that, It includes a first lens, a second lens, an aperture stop, 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 is an aspherical plastic lens with negative optical power, and is a convex-concave lens with a convex surface facing the object side and a concave surface facing the image side. The second lens is an aspherical plastic lens with negative optical power, and is a concave-convex lens with a concave surface facing the object side and a convex surface facing the image side. The third lens is an aspherical plastic lens with positive optical power, and is a central convex-central concave lens with a convex central area on the object side and a concave central area on the image side. The fourth lens is a glass spherical lens with positive optical power, and is a plano-convex lens with a flat surface facing the object side and a convex surface facing the image side. The fifth lens is an aspherical plastic lens with positive optical power, and is a biconvex lens with a convex surface on the object side and a convex surface on the image side. The sixth lens is an aspherical plastic lens with negative optical power, and is a biconcave lens with a concave surface on both the object side and the image side. The seventh lens is an aspherical plastic lens with positive optical power, and is a concave-convex central lens with a concave central region on the object side and a concave central region on the image side. The eighth lens is an aspherical plastic lens with negative optical power, and is a central convex-central concave lens with a convex central region on the object side and a concave central region on the image side.

2. The large aperture lens according to claim 1, characterized in that, The first lens through the eighth lens satisfy the following conditions: |V3-V5|≥17.0; V4+V5+V6+V7≤175.0; V3+V5+V7≤135.0; V2+V3+V4+V5≤175.0; |V1-V8|≤36.0; Wherein, V1-V8 are the Abbe numbers of the first lens to the eighth lens, respectively.

3. The large aperture lens according to claim 1, characterized in that, The large aperture lens meets the following conditions: TTL≤22.4; AAG / BFL ≥ 0.85; (EFL+BFL) / Fno≥10.0; ImgH / BFL ≥ 0.9; HFOV / TTL≤1.70; Wherein, TTL is the distance from the object side of the first lens to the imaging plane, AAG is the total air gap between the first lens and the eighth lens, BFL is the distance from the image side of the eighth lens to the image focal point, EFL is the focal length of the large aperture lens, Fno is the aperture coefficient of the large aperture lens, ImgH is the half image height, and HFOV is the half field of view.

4. The large aperture lens according to claim 1, characterized in that, The large aperture lens meets the following conditions: ALT / (T2+BFL)≥2.0; ALT / (T1+G12)≤4.5; ALT / (G23+G78)≤145.0; Wherein, ALT is the total center thickness of the first lens to the eighth lens, BFL is the distance from the image side of the eighth lens to the image focal point, T1 is the center thickness of the first lens, T2 is the center thickness of the second lens, G12 is the air gap between the center of the first lens and the center of the second lens, G23 is the air gap between the center of the second lens and the center of the third lens, and G78 is the air gap between the center of the seventh lens and the center of the eighth lens.

5. The large aperture lens according to claim 1, characterized in that, The large aperture lens satisfies the following condition: AAG / (T3+G45)≤2.90; Wherein, AAG is the total air gap between the first lens and the eighth lens, T3 is the center thickness of the third lens, and G45 is the air gap between the center of the fourth lens and the center of the fifth lens.

6. The large aperture lens according to claim 1, characterized in that, The large aperture lens satisfies the following condition: HFOV / (T6+T7+T8)≤8.0; Wherein, HFOV is the half field of view, T6 is the center thickness of the sixth lens, T7 is the center thickness of the seventh lens, and T8 is the center thickness of the eighth lens.

7. The large aperture lens according to claim 1, characterized in that, The large aperture lens meets the following conditions: (G45+G78+EFL) / (T3+T5)≥1.9; EFL / (G12+T2+G45)≥1.8; Wherein, EFL is the focal length of the large aperture lens, G12 is the air gap between the center of the first lens and the center of the second lens, G45 is the air gap between the center of the fourth lens and the center of the fifth lens, G78 is the air gap between the center of the seventh lens and the center of the eighth lens, T2 is the center thickness of the second lens, T3 is the center thickness of the third lens, and T5 is the center thickness of the fifth lens.

8. The large aperture lens according to claim 1, characterized in that, The large aperture lens meets the following conditions: TL / (G23+T3+G34+T4)≥3.5; TL / (G23+G34+T4)≤9.0; Where TL is the sum of AAG and ALT, AAG is the total air gap between the first lens and the eighth lens, and ALT is the total center thickness between the first lens and the eighth lens.

9. The large aperture lens according to claim 1, characterized in that, The large aperture lens meets the following conditions: (T1+T8) / T3≥0.8; (T3+T6) / T8≤3.00; Wherein, T1 is the center thickness of the first lens, T3 is the center thickness of the third lens, T6 is the center thickness of the sixth lens, and T8 is the center thickness of the third lens.

10. The large aperture lens according to claim 1, characterized in that, The large aperture lens meets the following conditions: (T7+G78+T8) / (G45+T5+G67)≥0.8; (T1+G23) / (G12+G78)≥0.3; G78 / (T2+T4)≥0.35; (G45+T5+G67) / T8≤3.0; Wherein, T1 is the center thickness of the first lens, T2 is the center thickness of the second lens, T4 is the center thickness of the fourth lens, T5 is the center thickness of the fifth lens, T7 is the center thickness of the seventh lens, and T8 is the center thickness of the third lens; G12 is the air gap between the center of the first lens and the center of the second lens, G23 is the air gap between the center of the second lens and the center of the third lens, G45 is the air gap between the center of the fourth lens and the center of the fifth lens, G67 is the air gap between the center of the sixth lens and the center of the seventh lens, and G78 is the air gap between the center of the seventh lens and the center of the eighth lens.

Images