Prime lens

Abstract

The invention discloses a prime lens. The prime lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged along an optical axis from an object side to an image side, the first lens has negative focal power; the second lens has positive focal power; the third lens has positive focal power; the fourth lens has positive focal power; the fifth lens has negative focal power; the sixth lens has positive focal power; the seventh lens has positive focal power; wherein the total length TTL of an optical system of the prime lens and the entrance pupil diameter ENPD meet the condition that TTL / ENPD is smaller than or equal to 13. By adopting the technical scheme, the prime lens has the characteristics of small volume and large aperture on the premise of ensuring that the prime lens has higher imaging resolution.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of optical devices, and in particular to a fixed-focus lens. Background Art

[0002] With the advancement of science and technology, optical lenses are widely used in various fields, and the performance requirements of optical lenses in various fields are getting higher and higher. For example, when optical lenses are used in the field of assisted driving, in order to ensure the safety and stability of driving, the assisted driving system needs to be equipped with an optical lens with a higher resolution so as to be able to collect images with higher clarity as the basis for assisted driving.

[0003] However, existing optical lenses with higher resolution cannot meet the requirements of large aperture and small size, which limits the application scenarios of existing optical lenses. Therefore, how to make optical lenses meet the requirements of large aperture and miniaturization while achieving high resolution has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] The present invention provides a fixed-focus lens, which can meet the requirements of large aperture and small volume while ensuring that the fixed-focus lens has high resolution.

[0005] The present invention provides a fixed-focus lens, which comprises: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence along an optical axis from an object side to an image side;

[0006] The first lens has negative optical power; the second lens has positive optical power; the third lens has positive optical power; the fourth lens has positive optical power; the fifth lens has negative optical power; the sixth lens has positive optical power; the seventh lens has positive optical power;

[0007] The total length TTL of the optical system of the fixed-focus lens and the entrance pupil diameter EPD satisfy the following relationship: TTL / EPD≤13.

[0008] Optionally, the total optical system length TTL of the fixed-focus lens and the effective focal length f of the fixed-focus lens satisfy: 7.2<TTL / f<8.3.

[0009] Optionally, an entrance pupil diameter EPD of the fixed-focus lens and an image height IH of the fixed-focus lens at a maximum field angle satisfy: 3.5<IH / EPD<4.

[0010] Optionally, the effective focal length f of the fixed-focus lens, the maximum field of view FOV of the fixed-focus lens, and the image height IH of the fixed-focus lens at the maximum field of view satisfy: (IH / 2) / (f×tan(FOV / 2)<0.6.

[0011] Optionally, the optical power of the third lens and the fourth lens satisfies:

[0012] 0.4≤Φ3 / Φ4≤0.8;

[0013] Wherein, Φ3 is the optical focal length of the third lens, and Φ4 is the optical focal length of the fourth lens.

[0014] Optionally, the optical power of the fifth lens and the sixth lens satisfies:

[0015] -1.6≤Φ5 / Φ6≤-1;

[0016] Wherein, Φ5 is the optical power of the fifth lens, and Φ6 is the optical power of the sixth lens.

[0017] Optionally, the optical power of the first lens to the seventh lens satisfies:

[0018] -0.7≤Φ1 / Φ≤-0.3;

[0019] 0≤Φ2 / Φ≤0.2;

[0020] 0≤Φ3 / Φ≤0.4;

[0021] 0.2≤Φ4 / Φ≤0.6;

[0022] -0.9≤Φ5 / Φ≤-0.5;

[0023] 0.4≤Φ6 / Φ≤0.8;

[0024] 0≤Φ7 / Φ≤0.2;

[0025] Among them, Φ1 is the optical focal power of the first lens, Φ2 is the optical focal power of the second lens, Φ3 is the optical focal power of the third lens, Φ4 is the optical focal power of the fourth lens, Φ5 is the optical focal power of the fifth lens, Φ6 is the optical focal power of the sixth lens, Φ7 is the optical focal power of the seventh lens, and Φ is the optical focal power of the fixed-focus lens.

[0026] Optionally, the focal lengths of the first lens to the seventh lens satisfy:

[0027] -3<f1 / f<-1.5;

[0028] 40<f2 / f<60;

[0029] 3.5<f3 / f<4.85;

[0030] 2.1<f4 / f<3.1;

[0031] -1.4<f5 / f<-1.15;

[0032] 1.46<f6 / f<1.86;

[0033] f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, and f is the effective focal length of the fixed-focus lens.

[0034] Optionally, the refractive index and Abbe number of the first lens to the seventh lens satisfy:

[0035] 1.72≤n1≤1.94,21≤v1≤51;

[0036] 1.63≤n2≤1.88,45≤v2≤60;

[0037] 1.81≤n3≤2.02,19≤v3≤36;

[0038] 1.52≤n4≤1.72,55≤v4≤69;

[0039] 1.75≤n5≤1.95,18≤v5≤29;

[0040] 1.40≤n6≤1.60,80≤v6≤86;

[0041] 1.58≤n7≤1.78,26≤v7≤36;

[0042] Among them, n1 is the refractive index of the first lens, v1 is the Abbe number of the first lens, n2 is the refractive index of the second lens, v2 is the Abbe number of the second lens, n3 is the refractive index of the third lens, v3 is the Abbe number of the third lens, n4 is the refractive index of the fourth lens, v4 is the Abbe number of the fourth lens, n5 is the refractive index of the fifth lens, v5 is the Abbe number of the fifth lens, n6 is the refractive index of the sixth lens, v6 is the Abbe number of the sixth lens, n7 is the refractive index of the seventh lens, v7 is the Abbe number of the seventh lens.

[0043] Optionally, the radius of curvature and center thickness of the second lens satisfy:

[0044] 0.6≤RS3 / (RS4+d2)≤1.0;

[0045] Among them, RS3 is the curvature radius of the object side surface of the second lens, RS4 is the curvature radius of the image side surface of the second lens, and d2 is the center thickness of the second lens.

[0046] Optionally, the radius of curvature of the fifth lens satisfies:

[0047] -0.1≤RS11 / RS10≤0.2;

[0048] Among them, RS10 is the curvature radius of the object side surface of the fifth lens, and RS11 is the curvature radius of the image side surface of the fifth lens.

[0049] Optionally, the image height ImgH corresponding to the object-side optical aperture D of the first lens and the maximum field angle of the fixed-focus lens satisfies:

[0050] 1.37≤D / ImgH≤1.62.

[0051] Optionally, the optical back focus BFL of the fixed-focus lens and the lens group length TL satisfy:

[0052] 0≤BFL / TL≤0.2.

[0053] The technical solution of the present invention adopts seven lenses with optical power to form a fixed-focus lens, and reasonably distributes the optical power of each lens, and sets the total optical system length TTL and the entrance pupil diameter ENPD of the fixed-focus lens to meet TTL / ENPD≤13, so that the fixed-focus lens can have a higher imaging resolution while meeting the requirements of small size and large aperture, thereby broadening the application field of the fixed-focus lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a structural schematic diagram of a fixed-focus lens provided by the present invention;

[0055] Figure 2 yes Figure 1 Schematic diagram of field curvature distortion curve of fixed focus lens shown;

[0056] Figure 3 yes Figure 1 Schematic diagram of axial aberration curve of fixed focus lens shown;

[0057] Figure 4 yes Figure 1 Schematic diagram of the light fan of the fixed focus lens shown;

[0058] Figure 5 A schematic structural diagram of another fixed-focus lens provided by the present invention;

[0059] Figure 6 yes Figure 5 Schematic diagram of field curvature distortion curve of fixed focus lens shown;

[0060] Figure 7 yes Figure 5 Schematic diagram of axial aberration curve of fixed focus lens shown;

[0061] Figure 8 yes Figure 5 Schematic diagram of the light fan of the fixed focus lens shown;

[0062] Fig. 9 A schematic structural diagram of another fixed-focus lens provided by the present invention;

[0063] Fig.10 yes Fig. 9 Schematic diagram of field curvature distortion curve of fixed focus lens shown;

[0064] Fig.11 yes Fig. 9 Schematic diagram of axial aberration curve of fixed focus lens shown;

[0065] Fig.12 yes Fig. 9 Schematic diagram of the light fan of a fixed-focus lens shown. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be fully described below in conjunction with the drawings in the embodiments of the present invention through specific implementation methods. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Various modifications and changes can be made in the present invention without departing from the spirit or scope of the present invention, which is obvious to those skilled in the art. Therefore, the present invention is intended to cover modifications and changes of the present invention that fall within the scope of the corresponding claims (technical solutions claimed for protection) and their equivalents.

[0067] Moreover, the words "first", "second" and similar words used in the embodiments of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one", "one" or "the" do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. In addition, the descriptions of the same, equal, etc. involved in the embodiments of the present disclosure do not mean that the two objects are completely equal in size and shape, and are allowed to be roughly the same or roughly equal within a certain error range.

[0068] It should be noted that the implementation methods provided in the embodiments of the present invention can be combined with each other if there is no contradiction.

[0069] Figure 1 is a schematic diagram of the structure of a fixed-focus lens provided by an embodiment of the present invention, such as Figure 1 As shown, the fixed-focus lens comprises: a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, a fifth lens 50, a sixth lens 60 and a seventh lens 70 arranged in sequence along the optical axis from the object side to the image side; the first lens 10 has a negative optical focal power; the second lens 20 has a positive optical focal power; the third lens 30 has a positive optical focal power; the fourth lens 40 has a positive optical focal power; the fifth lens 50 has a negative optical focal power; the sixth lens 60 has a positive optical focal power; and the seventh lens 70 has a positive optical focal power.

[0070] It can be understood that the focal power is equal to the difference between the convergence of the image-side light beam and the convergence of the object-side light beam, and it characterizes the ability of the optical system to deflect light. The larger the absolute value of the focal power, the stronger the ability to bend light, and the smaller the absolute value of the focal power, the weaker the ability to bend light. When the focal power is a positive number, the refraction of light is convergent; when the focal power is a negative number, the refraction of light is divergent. The focal power can be used to characterize a certain refractive surface of a lens (i.e., a surface of a lens), can be used to characterize a certain lens, and can also be used to characterize a system formed by multiple lenses (i.e., a lens group).

[0071] In this embodiment, each lens from the first lens 10 to the seventh lens 70 can be fixed to a lens barrel ( Figure 1 In the embodiment of the present invention, by setting the first lens 10 to have a negative focal power, the fixed-focus lens has a larger field of view; the second lens 20 is set to have a positive focal power, so that the spherical aberration and coma of the light passing through the first lens can be corrected, and the clarity and resolution of the image are improved; the third lens 30 is set to have a positive focal power, which is conducive to the light passing through the system more smoothly, and is convenient for correcting field curvature and astigmatism, and improving the clarity and quality of the image; the fourth lens 40 is set to have a positive focal power, and the fifth lens 50 is set to have a negative focal power, which is conducive to the light passing through the optical system of the fixed-focus lens more smoothly, while increasing the imaging area of ​​the fixed-focus lens, and improving the clarity and quality of the image; the sixth lens 60 is set to have a positive focal power, which is conducive to balancing the various aberrations generated by the fifth lens 50 and improving the imaging quality of the optical system of the fixed-focus lens; the seventh lens 70 is set to have a positive focal power, which is conducive to collecting light, ensuring the amount of light passing, and improving the relative illumination, while further balancing the various aberrations introduced by the previous lens, and improving the optical performance of the optical system of the entire fixed-focus lens. In this way, by reasonably allocating the optical focal length of each lens, it is ensured that the fixed-focus lens can have a higher imaging resolution while having the characteristics of large aperture and small volume, and is conducive to achieving good temperature characteristics, ensuring that the fixed-focus lens can still maintain good resolution under high and low temperature conditions.

[0072] In an optional embodiment, the optical focal lengths of the first lens 10 to the seventh lens 70 satisfy the following: -0.7≤Φ1 / Φ≤-0.3; 0≤Φ2 / Φ≤0.2; 0≤Φ3 / Φ≤0.4; 0.2≤Φ4 / Φ≤0.6; -0.9≤Φ5 / Φ≤-0.5; 0.4≤Φ6 / Φ≤0.8; 0≤Φ7 / Φ≤0.2; wherein Φ1 is the optical focal length of the first lens 10, Φ2 is the optical focal length of the second lens 20, Φ3 is the optical focal length of the third lens 30, Φ4 is the optical focal length of the fourth lens 40, Φ5 is the optical focal length of the fifth lens 50, Φ6 is the optical focal length of the sixth lens 60, Φ7 is the optical focal length of the seventh lens 70, and Φ is the optical focal length of the fixed-focus lens.

[0073] Among them, by setting the value range of the focal power Φ1 of the first lens 10 to -0.7≤Φ1 / Φ≤-0.3, it is helpful to expand the field angle of the fixed-focus lens; by setting the value range of the focal power Φ2 of the second lens 20 to 0≤Φ2 / Φ≤0.2, it is helpful to correct the spherical aberration and coma introduced by the previous lens, and improve the clarity and quality of imaging; by setting the value range of the focal power Φ3 of the third lens 30 to 0≤Φ3 / Φ≤0.4, it is helpful for light to pass through the optical system of the fixed-focus lens more smoothly, which is convenient for correcting field curvature and astigmatism, and improving the clarity and quality of imaging; by setting the value range of the focal power Φ4 of the fourth lens 40 to 0.2≤Φ4 / Φ≤0.6, and coordinating with the focal power value ranges of other lenses, the fixed-focus lens can have good temperature characteristics, ensuring the fixed The fixed-focus lens can still guarantee good resolution under high and low temperature conditions; by setting the value range of the optical power Φ5 of the fifth lens 50 to -0.9≤Φ5 / Φ≤-0.5, it is conducive to smoother passage of light through the optical system of the fixed-focus lens, while increasing the imaging area of ​​the fixed-focus lens, and improving the clarity and quality of imaging; by setting the value range of the optical power Φ6 of the sixth lens 60 to 0.4≤Φ6 / Φ≤0.8, it is conducive to balancing various aberrations generated by the fifth lens 50 and improving the imaging quality of the optical system; by setting the value range of the optical power Φ7 of the seventh lens 70 to 0≤Φ7 / Φ≤0.2, it is helpful for the optical system of the fixed-focus lens to collect light, ensure the light transmittance of the fixed-focus lens, improve the relative illumination, and further balance various aberrations introduced by the previous lens, thereby improving the optical performance of the entire optical system.

[0074] In an optional embodiment of the present invention, the optical power of the third lens 30 and the fourth lens 40 may satisfy: 0.4≤Φ3 / Φ4≤0.8; wherein Φ3 is the optical power of the third lens 30 , and Φ4 is the optical power of the fourth lens 40 .

[0075] In this embodiment, by setting the ratio of the optical power Φ3 of the third lens 30 to the optical power Φ4 of the fourth lens 40 to a value range of 0.4≤Φ3 / Φ4≤0.8, the light trend between the third lens 30 and the fourth lens 40 can be adjusted, the generation of aberrations can be suppressed, the clarity and quality of imaging can be improved, and at the same time, the assembly sensitivity can be reduced.

[0076] Optionally, the optical focal lengths of the fifth lens 50 and the sixth lens 60 satisfy: −1.6≤Φ5 / Φ6≤−1; wherein Φ5 is the optical focal length of the fifth lens 50 , and Φ6 is the optical focal length of the sixth lens 60 .

[0077] In this embodiment, by setting the ratio of the optical power Φ5 of the fifth lens 50 to the optical power Φ6 of the sixth lens 60 to a value range of -1.6≤Φ5 / Φ6≤-1, the light trend between the fifth lens 50 and the sixth lens 60 can be controlled, which is beneficial to reducing the aberration caused by the large angle, and is also beneficial to reducing the overall size of the fixed-focus lens, which helps to achieve the miniaturization of the fixed-focus lens.

[0078] In another optional embodiment, the focal lengths of the first lens 10 to the seventh lens 70 satisfy: -3<f1 / f<-1.5; 40<f2 / f<60; 3.5<f3 / f<4.85; 2.1<f4 / f<3.1; -1.4<f5 / f<-1.15; 1.46<f6 / f<1.86; f1 is the focal length of the first lens 10, f2 is the focal length of the second lens 20, f3 is the focal length of the third lens 30, f4 is the focal length of the fourth lens 40, f5 is the focal length of the fifth lens 50, f6 is the focal length of the sixth lens 60, and f is the effective focal length of the fixed-focus lens.

[0079] Among them, by setting the focal length f1 of the first lens 10 to a negative value, and making the focal length f1 of the first lens 10 and the effective focal length f of the fixed-focus lens satisfy -3<f1 / f<-1.5, it is beneficial to expand the field angle of the fixed-focus lens; by setting the focal length f2 of the second lens 20 to a positive value, and making the focal length f2 of the second lens 20 and the effective focal length f of the fixed-focus lens satisfy 40<f2 / f<60, it is helpful to correct the spherical aberration and coma introduced by the previous lens, and improve the clarity and quality of imaging; by setting the focal length f3 of the third lens 30 to a positive value, and making the focal length f3 of the third lens 30 and the effective focal length f of the fixed-focus lens satisfy 3.5<f3 / f<4.85, it is beneficial for light to pass through the system more smoothly, facilitate the correction of field curvature and astigmatism, and improve the clarity and quality of imaging; by setting the focal length f5 of the fifth lens 50 to a negative value, and making the focal length f5 of the fifth lens 50 The focal length f5 of the sixth lens 60 satisfies -1.4<f5 / f<-1.15 with the effective focal length f of the fixed-focus lens, which is conducive to smoother passage of light through the system, while increasing the imaging area of ​​the optical lens and improving the clarity and quality of the imaging; by setting the focal length f6 of the sixth lens 60 to a positive value, and making the focal length f6 of the sixth lens 60 and the effective focal length f of the fixed-focus lens satisfy 1.46<f6 / f<1.86, it is conducive to balancing various aberrations generated by the fifth lens and improving the imaging quality of the optical system; in addition, by setting the focal length f4 of the fourth lens 40 to a positive value, and making the focal length f4 of the fourth lens 40 and the effective focal length f of the fixed-focus lens satisfy 2.1<f4 / f<3.1, the focal length of the entire optical system of the fixed-focus lens can be reasonably distributed, which is conducive to achieving good temperature characteristics and ensuring that the fixed-focus lens can still maintain good resolution under high and low temperature conditions.

[0080] In an optional embodiment, the fifth lens 50 and the sixth lens 60 may form a cemented lens.

[0081] Among them, by making the fifth lens 50 and the sixth lens 60 form a cemented lens, the air space between the fifth lens 50 and the sixth lens 60 can be reduced, thereby helping to reduce the total length of the fixed-focus lens; at the same time, the cemented lens can minimize or eliminate chromatic aberration, so that various aberrations of the fixed-focus lens can be fully corrected, and under the premise of compact structure, the resolution can be improved, the optical performance such as distortion can be optimized, and the light loss caused by reflection between lenses can be reduced, and the illumination can be increased, thereby improving the image quality and the clarity of the fixed-focus lens. In addition, the use of the cemented lens can also reduce the assembly parts between the two lenses, simplify the assembly procedures in the manufacturing process of the fixed-focus lens, reduce costs, and reduce the tolerance sensitivity problems such as tilt / eccentricity of the lens unit caused by the assembly process.

[0082] Optionally, the total length TTL of the optical system of the fixed-focus lens and the entrance pupil diameter EPD satisfy: TTL / EPD≤13.

[0083] In this embodiment, by setting the ratio of the total optical system length TTL of the fixed-focus lens to the entrance pupil diameter EPD to be less than 13, the fixed-focus lens can meet the characteristics of a smaller total optical system length TTL and a larger entrance pupil diameter EPD, so that the fixed-focus lens can achieve a smaller relative aperture FNO, which is beneficial for the fixed-focus lens to achieve a large aperture characteristic and provide more incident light for the fixed-focus lens.

[0084] Optionally, the object-side optical aperture D of the first lens 10 and the image height ImgH corresponding to the maximum field angle of the fixed-focus lens satisfy: 1.37≤D / ImgH≤1.62.

[0085] In this embodiment, by setting the image height ImgH corresponding to the object-side optical aperture D of the first lens 10 and the maximum field angle of the fixed-focus lens to 1.37≤D / ImgH≤1.62, it is beneficial to the miniaturization design of the fixed-focus lens optical system, and it is also beneficial for the fixed-focus lens light system to have high pixel and high resolution characteristics, so that the fixed-focus lens meets the requirements of high imaging quality.

[0086] Optionally, the optical back focus BFL of the fixed-focus lens and the lens group length TL satisfy: 0≤BFL / TL≤0.2.

[0087] In the present embodiment, by setting the ratio of the optical back focus BFL of the fixed-focus lens to the lens group length TL to a value range of 0≤BFL / TL≤0.2, it is possible to achieve a longer back focus for the fixed-focus lens on the basis of miniaturization of the fixed-focus lens, which is beneficial to the assembly of the lenses of the fixed-focus lens and the modules thereof, thereby facilitating the improvement of production efficiency and reducing the production cost of the fixed-focus lens.

[0088] Optionally, the total length TTL of the optical system of the fixed-focus lens and the effective focal length f of the fixed-focus lens satisfy: 7.2<TTL / f<8.3.

[0089] By limiting the relationship between the total optical length and the effective focal length of the fixed-focus lens, the total optical system length of the fixed-focus lens can be controlled while satisfying the field angle range of the fixed-focus lens, so that the fixed-focus lens meets the characteristics of miniaturization.

[0090] Optionally, an entrance pupil diameter EPD of the fixed-focus lens and an image height IH of the fixed-focus lens at a maximum field angle satisfy: 3.5<IH / EPD<4.

[0091] Optionally, the effective focal length f of the fixed-focus lens, the maximum field of view FOV of the fixed-focus lens, and the image height IH of the fixed-focus lens at the maximum field of view satisfy: (IH / 2) / (f×tan(FOV / 2)<0.6.

[0092] Such a setting can achieve a smaller relative aperture FNO, which is conducive to achieving large aperture characteristics and providing more incident light for the fixed-focus lens.

[0093] Optionally, the object side surface of the first lens 10 is convex, and the image side surface is concave; the object side surface of the second lens 20 is concave, and the image side surface is convex; the object side surface of the third lens 30 is convex, and the image side surface is concave or flat; the object side surface of the fourth lens 40 is convex, and the image side surface is convex; the object side surface of the fifth lens 50 is concave or convex, and the image side surface is concave; the object side surface of the sixth lens 60 is convex, and the image side surface is convex; the object side surface of the seventh lens 70 is convex, and the image side surface is concave.

[0094] The object side of the lens can be understood as the surface of the lens close to the object plane, and the image side of the lens can be understood as the surface of the lens close to the image plane. In this embodiment, by reasonably setting the shape of each lens, the fixed-focus lens can have clear imaging quality and meet the requirements of miniaturization and large aperture of the fixed-focus lens, so that the fixed-focus lens can be applied to a wider range of application scenarios.

[0095] Optionally, the refractive index and Abbe number of the first lens 10 to the seventh lens 70 satisfy: 1.72≤n1≤1.94, 21≤v1≤51; 1.63≤n2≤1.88, 45≤v2≤60; 1.81≤n3≤2.02, 19≤v3≤36; 1.52≤n4≤1.72, 55≤v4≤69; 1.75≤n5≤1.95, 18≤v5≤29; 1.40≤n6≤1.60, 80≤v6≤86; 1.58≤n7≤1.78, 26≤v7≤36; wherein n1 is the first wherein n is the refractive index of the lens 10 , v1 is the Abbe number of the first lens 10 , n2 is the refractive index of the second lens 20 , v2 is the Abbe number of the second lens 20 , n3 is the refractive index of the third lens 30 , v3 is the Abbe number of the third lens 30 , n4 is the refractive index of the fourth lens 40 , v4 is the Abbe number of the fourth lens 40 , n5 is the refractive index of the fifth lens 50 , v5 is the Abbe number of the fifth lens 50 , n6 is the refractive index of the sixth lens 60 , v6 is the Abbe number of the sixth lens 60 , n7 is the refractive index of the seventh lens 70 , v7 is the Abbe number of the seventh lens 70 .

[0096] It can be understood that the refractive index is the ratio of the speed of light in a vacuum to the speed of light in the medium. It is mainly used to describe the material's ability to refract light. Different materials have different refractive indices, and the higher the refractive index of the material, the stronger the ability to refract incident light. The Abbe number is an index used to represent the dispersion ability of a transparent medium. The more severe the dispersion of the medium, the smaller the Abbe number; conversely, the milder the dispersion of the medium, the larger the Abbe number.

[0097] In this embodiment, by setting the refractive index and Abbe number of the lens, it is helpful to correct the position chromatic aberration and magnification chromatic aberration of the optical system of the fixed-focus lens, improve the resolution of the fixed-focus lens, and at the same time reduce the sensitivity of the optical system of the fixed-focus lens, improve the yield, and thus reduce the production cost.

[0098] Optionally, the radius of curvature and the center thickness of the second lens 20 satisfy: 0.6≤RS3 / (RS4+d2)≤1.0; wherein RS3 is the radius of curvature of the object side surface of the second lens 20, RS4 is the radius of curvature of the image side surface of the second lens 20, and d2 is the center thickness of the second lens 20.

[0099] In this embodiment, by limiting the relationship between the radius of curvature and the center thickness of the second lens 20 within the above range of values, the shape of the second lens 20 can be made close to a concentric circle, so that there is an optical path difference between the peripheral light and the central light, and the central light is diverged to enter the rear optical system, which helps to reduce the front port diameter and volume of the fixed-focus lens, and is conducive to miniaturization and low cost of the fixed-focus lens.

[0100] Optionally, the radius of curvature of the fifth lens 50 satisfies: −0.1≤RS11 / RS10≤0.2; wherein RS10 is the radius of curvature of the object-side surface of the fifth lens 50 , and RS11 is the radius of curvature of the image-side surface of the fifth lens 50 .

[0101] In this embodiment, by differentially setting the curvature radii of the image side and the object side of the fifth lens 50, and making the ratio of the curvature radius RS11 of the image side and the curvature radius RS10 of the object side of the fifth lens 50 satisfy the above relationship, it is beneficial to reduce the sensitivity of optical axis eccentricity, and it is also beneficial to expand the width of the incident light beam, thereby increasing the image plane height and enabling the system to have high pixel characteristics.

[0102] Based on the above embodiment, the fixed-focus lens may further include an aperture 80 and a filter 90; the aperture 80 is arranged in the light path between the third lens 30 and the fourth lens 40; the filter 90 is arranged in the light path between the seventh lens 70 and the image plane.

[0103] Specifically, the aperture 80 can adjust the propagation direction of the light beam, which is beneficial to improving the imaging quality, and the aperture 80 in the fixed-focus lens is located in the optical path between the third lens 30 and the fourth lens 40. The aperture 80 is located in the middle of the fixed-focus lens to ensure that the front and rear apertures of the fixed-focus lens are minimized. The filter 90 is arranged in the optical path between the seventh lens 70 and the image plane to filter out stray light and improve the imaging effect. In an exemplary embodiment, the filter 90 can be an infrared filter.

[0104] In summary, the embodiments of the present invention use seven lenses with optical power to form a fixed-focus lens, and reasonably allocate the optical power of each lens, and reasonably select materials and design the shape of each lens, so that the fixed-focus lens can simultaneously meet the requirements of small size, large aperture, high resolution, and high resolution, thereby broadening the application field of the fixed-focus lens.

[0105] Specific embodiments of the fixed-focus lens applicable to the above-mentioned embodiments are further described below with reference to the accompanying drawings.

[0106] In a feasible embodiment, Table 1 describes in detail the following in a feasible implementation manner: Figure 1 Specific optical and physical parameters of the fixed-focus lens shown.

[0107] Table 1 Optical physical parameter design of a fixed focus lens

[0108] Example 1 Lower limit Upper limit Φ1 / Φ -0.533 -0.7 -0.3 Φ2 / Φ 0.015 0.0 0.2 Φ3 / Φ 0.236 0.0 0.4 Φ4 / Φ 0.372 0.2 0.6 Φ5 / Φ -0.729 -0.9 -0.5 Φ6 / Φ 0.596 0.4 0.8 Φ7 / Φ 0.012 0.0 0.2 Φ3 / Φ4 0.635 0.4 0.8 Φ5 / Φ6 -1.223 -1.6 -1.0 n1 1.800 1.72 1.94 n2 1.730 1.63 1.88 n3 1.900 1.81 2.02 n4 1.620 1.52 1.72 n5 1.850 1.75 1.95 n6 1.500 1.40 1.60 n7 1.680 1.58 1.78 v1 46.600 21 51 v2 54.700 45 60 v3 31.300 19 36 v4 63.900 55 69 v5 23.800 18 29 v6 81.600 80 86 v7 31.400 26 36 RS3 / (RS4+d2) 0.797 0.6 1.0 RS11 / RS10 0.069 -0.1 0.2 TTL / ENPD 12.520 13 D / Img 1.518 1.37 1.62 BEL / TL 0.126 0 0.2 f2 / f 65.3089 41 72 RS1 / RS2 4.1709 3.75 4.82 (f1+f2+f3) / f 67.6633 75 43 (RS6+RS8+RS9) / BFL +∞ 51 +∞

[0109] Table 2 shows the design parameters of the surface type, curvature radius, thickness and material of each lens in a fixed-focus lens corresponding to Table 1.

[0110] Table 2 Parameter design of each lens in fixed focus lens

[0111] Surface number Face Type Curvature radius / mm Thickness / mm Refractive Index Abbe number OBJ Physical surface Infinity Infinity S1 Spherical 18.3635 1.0293 1.800 46.600 S2 Spherical 4.4028 4.7991 S3 Spherical -7.5997 5.7267 1.730 54.700 S4 Spherical -9.6371 0.1000 S5 Spherical 15.2318 3.1613 1.900 31.300 S6 Spherical Infinity 0.2115 S7 Aperture Infinity 0.7812 S8 even aspherical surface 8.9342 3.9153 1.620 63.900 S9 even aspherical surface -21.4878 0.0999 S10 Spherical 63.1149 0.9521 1.850 23.800 S11 Spherical 4.3246 3.9008 1.500 81.600 S12 Spherical -10.2909 0.0994 S13 even aspherical surface 13.1060 2.4815 1.680 31.400 S14 even aspherical surface 12.8319 0.8998 S15 Spherical Infinity 0.8000 1.520 64.200 S16 Spherical Infinity 1.7325 IMA Spherical Infinity 0.0000

[0112] The fixed-focus lens of this embodiment includes a first lens 10, a second lens 20, a third lens 30, an aperture 80, a fourth lens 40, a fifth lens 50, a sixth lens 60, a seventh lens 70 and a filter glass 90, which are arranged in sequence along the optical axis from the object side to the image side. The surface numbers are numbered according to the surface sequence of each lens, wherein "S1" represents the object side of the first lens, "S2" represents the image side of the first lens, and so on; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side, wherein "Infinity" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the central axial distance from the current surface to the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light; and the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to the light.

[0113] The aspherical surface shape of the fixed-focus lens of this embodiment can be defined by the following aspherical surface formula, but is not limited to the following expression method:

[0114]

[0115] Among them, Z is the axial vector height of the aspheric surface, c is the basic curvature at the vertex of the aspheric surface, k is the conic section constant, r is the radial coordinate in the direction perpendicular to the optical axis, and A, B, C, D, E, F, and G correspond to the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, and sixteenth-order coefficients of the aspheric polynomial, respectively.

[0116] Table 3 Aspheric coefficients of a fixed-focus lens

[0117] S8 S9 S13 S14 k 7.93E-01 -4.18E+00 1.44E+00 3.25E-01 A -3.75E-04 2.44E-05 -1.42E-03 -1.62E-03 B -1.04E-05 -5.44E-05 -1.28E-05 -3.41E-05 C 1.32E-06 1.33E-05 7.40E-07 2.56E-06 D -1.96E-07 -1.62E-06 -7.41E-08 -8.21E-08 E 7.51E-09 7.02E-08 5.49E-09 6.12E-11 F 1.77E-15 -2.16E-13 -2.88E-11 1.05E-10 G 6.52E-16 -1.55E-13 -1.08E-12 -1.67E-12

[0118] Among them, -3.75E-04 means that the coefficient A of the surface number S8 is -3.75×10 -4 .

[0119] Figure 2 yes Figure 1 The schematic diagram of the field curvature distortion curve of the fixed focus lens is shown in FIG. Figure 2 As shown in the figure, the curves of different colors represent different wavelengths (656nm, 588nm, 546nm, 486nm, 436nm) of the system imaging. Figure 2 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within -0.03mm to 0.03mm, indicating that the fixed-focus lens can correct the field curvature well.

[0120] Figure 3 yes Figure 1 The schematic diagram of the axial aberration curve of the fixed focus lens is shown in FIG. Figure 3 As shown in the figure, the curves of different colors represent different wavelengths (656nm, 588nm, 546nm, 486nm, 436nm) of the system imaging. Figure 3 It can be seen that the offset of axial aberration is controlled within ±0.02mm, which means that the fixed-focus lens can correct axial aberration well.

[0121] Figure 4 yes Figure 1 The schematic diagram of the light fan of the fixed focus lens is shown in Figure 4 As shown in the figure, the schematic diagrams of the light fan at different field angles (0.00°, 10.00°, 20.00°, 30.00°, 40.00°, 50.00°, 60.00°, 70.00°) are respectively reflected. In the schematic diagram of the light fan at each field angle, curves of different colors represent different wavelengths of system imaging (656nm, 588nm, 546nm, 486nm, 436nm). Figure 4 It can be seen that the deviation of the light relative to the main light coordinate is controlled within ±25um, which means that the fixed-focus lens can better control the aberration.

[0122] In another possible embodiment, Figure 5is a schematic diagram of the structure of another fixed-focus lens provided in an embodiment of the present invention. Table 4 describes in detail another feasible implementation manner. Figure 5 Specific optical and physical parameters of the fixed-focus lens shown.

[0123] Table 4 Another optical physical parameter design of fixed focus lens

[0124] Example 2 Lower limit Upper limit Φ1 / Φ -0.551 -0.7 -0.3 Φ2 / Φ 0.017 0.0 0.2 Φ3 / Φ 0.247 0.0 0.4 Φ4 / Φ 0.378 0.2 0.6 Φ5 / Φ -0.829 -0.9 -0.5 Φ6 / Φ 0.607 0.4 0.8 Φ7 / Φ 0.062 0.0 0.2 Φ3 / Φ4 0.654 0.4 0.8 Φ5 / Φ6 -1.365 -1.6 -1.0 n1 1.835 1.72 1.94 n2 1.775 1.63 1.88 n3 1.916 1.81 2.02 n4 1.617 1.52 1.72 n5 1.856 1.75 1.95 n6 1.495 1.40 1.60 n7 1.683 1.58 1.78 v1 36.185 21 51 v2 55.101 45 60 v3 23.998 19 36 v4 63.862 55 69 v5 21.995 18 29 v6 81.381 80 86 v7 31.440 26 36 RS3 / (RS4+d2) 0.794 0.6 1.0 RS11 / RS10 -0.007 -0.1 0.2 TTL / ENPD 12.483 13 D / Img 1.468 1.37 1.62 BEL / TL 0.156 0 0.2 f2 / f 58.6357 41 72 RS1 / RS2 4.3420 3.75 4.82 (f1+f2+f3) / f 60.8669 75 43 (RS6+RS8+RS9) / BFL 83.2664 51 +∞

[0125] Table 5 shows the design parameters of the surface type, curvature radius, thickness, material, etc. of each lens in another fixed-focus lens corresponding to Table 4.

[0126] Table 5 Another parameter design of each lens in the fixed focus lens

[0127] Surface number Face Type Curvature radius / mm Thickness / mm Refractive Index Abbe number OBJ Physical surface Infinity Infinity S1 Spherical 19.9724 0.9000 1.835 36.185 S2 Spherical 4.5998 5.1959 S3 Spherical -7.4941 5.8007 1.775 55.101 S4 Spherical -9.6401 0.2014 S5 Spherical 14.4997 2.2291 1.916 23.998 S6 Spherical 358.5201 0.0800 S7 Aperture Infinity 1.1402 S8 even aspherical surface 9.1338 3.8605 1.617 63.862 S9 even aspherical surface -19.9485 0.1019 S10 Spherical -607.6665 0.9549 1.856 21.995 S11 Spherical 4.2307 3.9941 1.495 81.381 S12 Spherical -10.1463 0.0974 S13 even aspherical surface 13.8881 2.2788 1.683 31.440 S14 even aspherical surface 18.7843 0.9000 S15 Spherical Infinity 0.8000 1.517 64.199 S16 Spherical Infinity 2.4758 IMA Spherical Infinity 0.0000

[0128] The fixed-focus lens of this embodiment includes a first lens 10, a second lens 20, a third lens 30, an aperture 80, a fourth lens 40, a fifth lens 50, a sixth lens 60, a seventh lens 70 and a filter glass 90, which are arranged in sequence along the optical axis from the object side to the image side. The surface numbers are numbered according to the surface sequence of each lens, wherein "S1" represents the object side of the first lens, "S2" represents the image side of the first lens, and so on; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side, wherein "Infinity" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the central axial distance from the current surface to the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light; and the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to the light.

[0129] The aspherical surface shape of the fixed-focus lens of this embodiment can be defined by the following aspherical surface formula, but is not limited to the following expression method:

[0130]

[0131] Among them, Z is the axial vector height of the aspheric surface, c is the basic curvature at the vertex of the aspheric surface, k is the conic section constant, r is the radial coordinate in the direction perpendicular to the optical axis, and A, B, C, D, E, F, and G correspond to the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, and sixteenth-order coefficients of the aspheric polynomial, respectively.

[0132] Table 6 Aspheric coefficients of another fixed-focus lens

[0133] S8 S9 S13 S14 k 6.14E-01 5.30E+00 1.15E+00 6.97E-01 A -4.08E-04 -1.38E-04 -1.45E-03 -1.61E-03 B -1.42E-05 -5.36E-05 -1.14E-05 -2.18E-05 C 1.03E-06 1.27E-05 1.02E-06 2.96E-06 D -1.85E-07 -1.81E-06 -6.24E-08 -1.84E-07 E 9.03E-09 1.06E-07 9.73E-10 1.81E-09 F 1.78E-10 8.15E-10 3.47E-10 3.95E-10 G -2.56E-11 -2.66E-10 -1.14E-11 -1.25E-11

[0134] Among them, -4.08E-04 means that the coefficient A of the surface number S8 is -4.08×10 -4 .

[0135] Figure 6 yes Figure 5 The schematic diagram of the field curvature distortion curve of the fixed focus lens is shown in FIG. Figure 6 As shown in the figure, the curves of different colors represent different wavelengths (656nm, 588nm, 546nm, 486nm, 436nm) of the system imaging. Figure 6 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within -0.03mm~0.04mm, which means that the fixed-focus lens can correct the field curvature well.

[0136] Figure 7 yes Figure 5 The schematic diagram of the axial aberration curve of the fixed focus lens is shown in FIG. Figure 7 As shown in the figure, the curves of different colors represent different wavelengths (656nm, 588nm, 546nm, 486nm, 436nm) of the system imaging. Figure 7 It can be seen that the offset of axial aberration is controlled within ±0.02mm, which means that the fixed-focus lens can correct axial aberration well.

[0137] Figure 8 yes Figure 5 The schematic diagram of the light fan of the fixed focus lens is shown in FIG. Figure 8 As shown in the figure, the schematic diagrams of the light fan at different field angles (0.00°, 10.00°, 20.00°, 30.00°, 40.00°, 50.00°, 60.00°, 70.00°) are respectively reflected. In the schematic diagram of the light fan at each field angle, curves of different colors represent different wavelengths of system imaging (656nm, 588nm, 546nm, 486nm, 436nm). Figure 8 It can be seen that the deviation of the light relative to the main light coordinate is controlled within ±25um, which means that the fixed-focus lens can better control the aberration.

[0138] In another possible embodiment, Fig. 9 is a schematic diagram of the structure of another fixed-focus lens provided in an embodiment of the present invention. Table 7 describes in detail another feasible implementation method. Fig. 9 Specific optical and physical parameters of the fixed-focus lens shown.

[0139] Table 7 Another optical physical parameter design of fixed focus lens

[0140] Example 3 Lower limit Upper limit Φ1 / Φ -0.542 -0.7 -0.3 Φ2 / Φ 0.022 0.0 0.2 Φ3 / Φ 0.222 0.0 0.4 Φ4 / Φ 0.382 0.2 0.6 Φ5 / Φ -0.733 -0.9 -0.5 Φ6 / Φ 0.580 0.4 0.8 Φ7 / Φ 0.029 0.0 0.2 Φ3 / Φ4 0.580 0.4 0.8 Φ5 / Φ6 -1.263 -1.6 -1.0 n1 1.816 1.72 1.94 n2 1.729 1.63 1.88 n3 1.906 1.81 2.02 n4 1.616 1.52 1.72 n5 1.847 1.75 1.95 n6 1.495 1.40 1.60 n7 1.683 1.58 1.78 v1 39.373 21 51 v2 50.000 45 60 v3 26.370 19 36 v4 60.276 55 69 v5 22.344 18 29 v6 84.963 80 86 v7 31.440 26 36 RS3 / (RS4+d2) 0.802 0.6 1.0 RS11 / RS10 0.065 -0.1 0.2 TTL / ENPD 12.477 13 D / Img 1.501 1.37 1.62 BEL / TL 0.135 0 0.2 f2 / f 45.9005 41 72 RS1 / RS2 4.3226 3.75 4.82 (f1+f2+f3) / f 48.5670 75 43 (RS6+RS8+RS9) / BFL 56.6585 51 +∞

[0141] Table 8 shows the design parameters of the surface type, curvature radius, thickness, material, etc. of each lens in another fixed-focus lens corresponding to Table 7.

[0142] Table 8 Another parameter design of each lens in the fixed focus lens

[0143] Surface number Face Type Curvature radius / mm Thickness / mm Refractive Index Abbe number OBJ Physical surface Infinity Infinity S1 Spherical 19.6206 0.9638 1.816 39.373 S2 Spherical 4.5390 4.9321 S3 Spherical -7.5893 5.8715 1.729 50.000 S4 Spherical -9.5354 0.0670 S5 Spherical 15.4657 2.2000 1.906 26.370 S6 Spherical 219.3440 0.3976 S7 Aperture Infinity 1.0954 S8 even aspherical surface 8.9714 3.8913 1.616 60.276 S9 even aspherical surface -19.6043 0.0999 S10 Spherical 66.6363 0.9521 1.847 22.344 S11 Spherical 4.3504 4.2650 1.495 84.963 S12 Spherical -10.9812 0.0636 S13 even aspherical surface 13.5599 2.4273 1.683 31.440 S14 even aspherical surface 14.6344 0.7823 S15 Spherical Infinity 0.8000 1.519 64.199 S16 Spherical Infinity 2.1014 IMA Spherical Infinity 0.0000

[0144] The fixed-focus lens of this embodiment includes a first lens 10, a second lens 20, a third lens 30, an aperture 80, a fourth lens 40, a fifth lens 50, a sixth lens 60, a seventh lens 70 and a filter glass 90, which are arranged in sequence along the optical axis from the object side to the image side. The surface numbers are numbered according to the surface sequence of each lens, wherein "S1" represents the object side of the first lens, "S2" represents the image side of the first lens, and so on; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side, wherein "Infinity" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the central axial distance from the current surface to the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light; and the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to the light.

[0145] The aspherical surface shape of the fixed-focus lens of this embodiment can be defined by the following aspherical surface formula, but is not limited to the following expression method:

[0146]

[0147] Among them, Z is the axial vector height of the aspheric surface, c is the basic curvature at the vertex of the aspheric surface, k is the conic section constant, r is the radial coordinate in the direction perpendicular to the optical axis, and A, B, C, D, E, F, and G correspond to the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, and sixteenth-order coefficients of the aspheric polynomial, respectively.

[0148] Table 9 Aspheric coefficients of another fixed-focus lens

[0149] S8 S9 S13 S14 k 5.74E-01 4.21E+00 5.15E-01 -4.72E-01 A -4.15E-04 -1.12E-04 -1.47E-03 -1.69E-03 B -1.31E-05 -4.31E-05 -5.97E-06 -1.51E-05 C 1.07E-06 1.24E-05 -8.22E-07 9.44E-07 D -1.84E-07 -1.88E-06 6.98E-08 -1.74E-08 E 8.91E-09 9.12E-08 -1.69E-09 -1.02E-09 F 1.87E-10 5.32E-09 -8.98E-11 5.95E-11 G -2.58E-11 -5.17E-10 1.01E-11 4.28E-13

[0150] Among them, -4.15E-04 means that the coefficient A of the surface number S8 is -4.15×10 -4 .

[0151] Fig.10 yes Fig. 9 The schematic diagram of the field curvature distortion curve of the fixed focus lens is shown in FIG. Fig.10 As shown in the figure, the curves of different colors represent different wavelengths (656nm, 588nm, 546nm, 486nm, 436nm) of the system imaging. Fig.10It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within -0.03mm~0.04mm, which means that the fixed-focus lens can correct the field curvature well.

[0152] Fig.11 yes Fig. 9 The schematic diagram of the axial aberration curve of the fixed focus lens is shown in FIG. Fig.11 As shown in the figure, the curves of different colors represent different wavelengths (656nm, 588nm, 546nm, 486nm, 436nm) of the system imaging. Fig.11 It can be seen that the offset of axial aberration is controlled within ±0.02mm, which means that the fixed-focus lens can correct axial aberration well.

[0153] Fig.12 yes Fig. 9 The schematic diagram of the light fan of the fixed focus lens is shown in FIG. Fig.12 As shown in the figure, the schematic diagrams of the light fan at different field angles (0.00°, 10.00°, 20.00°, 30.00°, 40.00°, 50.00°, 60.00°, 70.00°) are respectively reflected. In the schematic diagram of the light fan at each field angle, curves of different colors represent different wavelengths of system imaging (656nm, 588nm, 546nm, 486nm, 436nm). Fig.12 It can be seen that the deviation of the light relative to the main light coordinate is controlled within ±25um, which means that the fixed-focus lens can better control the aberration.

[0154] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments 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 fixed-focus lens, characterized in that: include: A first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence along the optical axis from the object side to the image side; The first lens has negative optical power; the second lens has positive optical power; the third lens has positive optical power; the fourth lens has positive optical power; the fifth lens has negative optical power; the sixth lens has positive optical power; the seventh lens has positive optical power; The total length TTL of the optical system of the fixed-focus lens and the entrance pupil diameter EPD satisfy the following relationship: TTL / EPD≤13.

2. The fixed-focus lens according to claim 1, characterized in that: The total optical system length TTL of the fixed-focus lens and the effective focal length f of the fixed-focus lens satisfy the following conditions: 7.2<TTL / f<8.

3.

3. The fixed-focus lens according to claim 1, characterized in that: An entrance pupil diameter EPD of the fixed-focus lens and an image height IH of the fixed-focus lens at a maximum field angle satisfy the following conditions: 3.5<IH / EPD<4.

4. The fixed-focus lens according to claim 1, characterized in that: The effective focal length f of the fixed-focus lens, the maximum field of view FOV of the fixed-focus lens, and the image height IH of the fixed-focus lens at the maximum field of view satisfy: (IH / 2) / (f×tan(FOV / 2)<0.

6.

5. The fixed-focus lens according to claim 1, wherein: The optical power of the third lens and the fourth lens satisfies: 0.4≤Φ3 / Φ4≤0.8; Wherein, Φ3 is the optical focal length of the third lens, and Φ4 is the optical focal length of the fourth lens.

6. The fixed-focus lens according to claim 1, wherein: The optical power of the fifth lens and the sixth lens satisfies: -1.6≤Φ5 / Φ6≤-1; Wherein, Φ5 is the optical power of the fifth lens, and Φ6 is the optical power of the sixth lens.

7. The fixed-focus lens according to claim 1, wherein: The optical power of the first lens to the seventh lens satisfies: -0.7≤Φ1 / Φ≤-0.3; 0≤Φ2 / Φ≤0.2; 0≤Φ3 / Φ≤0.4; 0.2≤Φ4 / Φ≤0.6; -0.9≤Φ5 / Φ≤-0.5; 0.4≤Φ6 / Φ≤0.8; 0≤Φ7 / Φ≤0.2; Φ1 is the optical focal power of the first lens, Φ2 is the optical focal power of the second lens, Φ3 is the optical focal power of the third lens, Φ4 is the optical focal power of the fourth lens, Φ5 is the optical focal power of the fifth lens, Φ6 is the optical focal power of the sixth lens, Φ7 is the optical focal power of the seventh lens, and Φ is the optical focal power of the fixed-focus lens.

8. The fixed-focus lens according to claim 1, wherein: The focal lengths of the first lens to the seventh lens satisfy: -3<f1 / f<-1.5; 40<f2 / f<60; 3.5<f3 / f<4.85; 2.1<f4 / f<3.1; -1.4<f5 / f<-1.15; 1.46<f6 / f<1.86; f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, and f is the effective focal length of the fixed-focus lens.

9. The fixed-focus lens according to claim 1, wherein: The refractive index and Abbe number of the first to seventh lenses satisfy: 1.72≤n1≤1.94,21≤v1≤51; 1.63≤n2≤1.88,45≤v2≤60; 1.81≤n3≤2.02,19≤v3≤36; 1.52≤n4≤1.72,55≤v4≤69; 1.75≤n5≤1.95,18≤v5≤29; 1.40≤n6≤1.60,80≤v6≤86; 1.58≤n7≤1.78,26≤v7≤36; Among them, n1 is the refractive index of the first lens, v1 is the Abbe number of the first lens, n2 is the refractive index of the second lens, v2 is the Abbe number of the second lens, n3 is the refractive index of the third lens, v3 is the Abbe number of the third lens, n4 is the refractive index of the fourth lens, v4 is the Abbe number of the fourth lens, n5 is the refractive index of the fifth lens, v5 is the Abbe number of the fifth lens, n6 is the refractive index of the sixth lens, v6 is the Abbe number of the sixth lens, n7 is the refractive index of the seventh lens, v7 is the Abbe number of the seventh lens.

10. The fixed-focus lens according to claim 1, wherein: The radius of curvature and center thickness of the second lens satisfy: 0.6≤RS3 / (RS4+d2)≤1.0; Among them, RS3 is the curvature radius of the object side surface of the second lens, RS4 is the curvature radius of the image side surface of the second lens, and d2 is the center thickness of the second lens.

11. The fixed-focus lens according to claim 1, wherein: The curvature radius of the fifth lens satisfies: -0.1≤RS11 / RS10≤0.2; Among them, RS10 is the curvature radius of the object side surface of the fifth lens, and RS11 is the curvature radius of the image side surface of the fifth lens.

12. The fixed-focus lens according to claim 1, wherein: The image height ImgH corresponding to the object-side optical aperture D of the first lens and the maximum field angle of the fixed-focus lens satisfies: 1.37≤D / ImgH≤1.

62.

13. The fixed-focus lens according to claim 1, wherein: The optical back focus BFL of the fixed focus lens and the lens group length TL satisfy: 0≤BFL / TL≤0.2.

Images