prime lens

Abstract

The application discloses a fixed-focus lens, which comprises a first lens group and a second lens group in sequence from an object side to an image side along an optical axis; wherein the first lens group comprises a first lens with negative refractive power, a second lens with negative refractive power, a third lens with negative refractive power and a fourth lens with positive refractive power in sequence from the object side to the image side; the second lens group comprises a fifth lens with positive refractive power, a sixth lens with positive refractive power, a seventh lens with negative refractive power and an eighth lens with positive refractive power in sequence from the object side to the image side; and the effective focal length fa of the first lens group and the total effective focal length f of the fixed-focus lens satisfy: 2.5<=|fa / f|<=6.

Description

Technical Field

[0001] This application relates to the field of optical devices, specifically to a fixed-focus lens. Background Technology

[0002] With the development of optical imaging lenses, they are widely used in panoramic monitoring, drones, action cameras and automotive lenses. As the demand for optical imaging lenses continues to increase, higher requirements are being placed on their imaging quality.

[0003] However, existing optical imaging lenses often have some problems. For example, they may have a small field of view; or a small aperture, which may not be able to meet the requirements for a large aperture; or they may not be able to achieve high resolution while meeting the requirements for high brightness. Summary of the Invention

[0004] This application provides a fixed-focus lens comprising, along the optical axis from the object side to the image side, a first lens group and a second lens group in sequence; wherein, the first lens group comprises, from the object side to the image side, a first lens with negative optical power, a second lens with negative optical power, a third lens with negative optical power, and a fourth lens with positive optical power; the second lens group comprises, from the object side to the image side, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, and an eighth lens with positive optical power; the effective focal length fa of the first lens group and the total effective focal length f of the fixed-focus lens satisfy: 2.5≤|fa / f|≤6.

[0005] According to an exemplary embodiment of this application, the fixed-focus lens further includes a ninth lens having negative optical power, the ninth lens being located on the object side of the first lens.

[0006] According to an exemplary embodiment of this application, the object-side surface of the ninth lens is convex, and the image-side surface is concave.

[0007] According to an exemplary embodiment of this application, the object-side surface of the first lens is convex, and the image-side surface is concave. The object-side surface of the second lens is convex, and the image-side surface is concave. The object-side surface of the third lens is concave. The image-side surface of the fourth lens is convex. The object-side surface of the fifth lens is convex. The object-side surface of the sixth lens is convex, and the image-side surface is convex. The object-side surface of the seventh lens is concave. The object-side surface of the eighth lens is convex.

[0008] According to an exemplary embodiment of this application, the sixth lens and the seventh lens are cemented together to form a cemented lens.

[0009] According to an exemplary embodiment of this application, the effective focal length f9 of the ninth lens and the effective focal length f1 of the first lens satisfy: 6.5≤f9 / f1≤19.7.

[0010] According to an exemplary embodiment of this application, the effective focal length f1 of the first lens and the total effective focal length f of the fixed-focus lens satisfy: -5≤f1 / f≤-3.

[0011] According to an exemplary embodiment of this application, the combined focal length f12 of the first lens and the second lens and the total effective focal length f of the fixed-focus lens satisfy: -2.2≤f12 / f≤-1.2.

[0012] According to an exemplary embodiment of this application, the effective focal length f2 of the second lens and the radius of curvature R22 of the image side surface of the second lens satisfy: -3.3≤f2 / R22≤-1.96.

[0013] According to an exemplary embodiment of this application, the effective focal length f3 of the third lens and the effective focal length fa of the first lens group satisfy: 1≤f3 / fa≤4.

[0014] According to an exemplary embodiment of this application, the effective focal length f4 of the fourth lens and the effective focal length fa of the first lens group satisfy: 0.52≤|f4 / fa|≤1.87.

[0015] According to an exemplary embodiment of this application, the radius of curvature R42 of the image side of the fourth lens and the radius of curvature R51 of the object side of the fifth lens satisfy: |(R42+R51) / (R42-R51)|≤0.7.

[0016] According to an exemplary embodiment of this application, the effective focal length f4 of the fourth lens and the effective focal length f5 of the fifth lens satisfy: 0.4≤f4 / f5≤1.5.

[0017] According to an exemplary embodiment of this application, the combined focal length f67 of the sixth and seventh lenses and the effective focal length fb of the second lens group satisfy: 2≤|f67| / fb≤8.

[0018] According to an exemplary embodiment of this application, the effective focal length f6 of the sixth lens and the effective focal length f7 of the seventh lens satisfy: -1.86≤f6 / f7≤-0.85.

[0019] According to an exemplary embodiment of this application, the Abbe number Vd6 of the sixth lens, the Abbe number Vd7 of the seventh lens, and the combined focal length f67 of the sixth and seventh lenses satisfy: 1≤(Vd6-Vd7) / |f67|≤7.

[0020] According to an exemplary embodiment of this application, the effective focal length f8 of the eighth lens and the total effective focal length f of the fixed-focus lens satisfy: 2.6≤f8 / f≤3.8.

[0021] According to an exemplary embodiment of this application, the effective focal length f8 of the eighth lens and the radius of curvature R82 of the image side surface of the eighth lens satisfy: |f8 / R82|≤1.

[0022] According to an exemplary embodiment of this application, the effective focal length fb of the second lens group and the total effective focal length f of the fixed-focus lens satisfy: 2.7≤fb / f≤3.6.

[0023] According to an exemplary embodiment of this application, the effective focal length fa of the first lens group and the effective focal length fb of the second lens group satisfy: 0.8≤|fa / fb|≤1.8.

[0024] According to an exemplary embodiment of this application, the maximum field of view (FOV) of the fixed-focus lens, the image height (H) corresponding to the maximum field of view of the fixed-focus lens, and the maximum aperture (D) of the fixed-focus lens satisfy: 1.65° / mm 2 ≤FOV / H / D≤2.2° / mm 2 .

[0025] According to an exemplary embodiment of this application, the image height H corresponding to the maximum field of view of the fixed-focus lens and the maximum aperture D of the fixed-focus lens satisfy: 4.8≤D / H≤5.5.

[0026] According to an exemplary embodiment of this application, the total optical length TTL of a fixed-focus lens and the maximum aperture D of the fixed-focus lens satisfy the following condition: 0.9≤TTL / D≤1.

[0027] According to an exemplary embodiment of this application, the back focal length BFL of the fixed-focus lens and the total effective focal length f of the fixed-focus lens satisfy: 1.23≤BFL / f≤1.59.

[0028] According to an exemplary embodiment of this application, the total effective focal length f of the fixed-focus lens, the effective focal length f1 of the first lens, the effective focal length f4 of the fourth lens, and the combined focal length f67 of the sixth and seventh lenses satisfy: -5.9mm 2 ≤f×f1×f4 / |f67|≤-1.4mm 2 .

[0029] According to an exemplary embodiment of this application, the fixed-focus lens satisfies at least one of the following conditions: 2.5 ≤ |fa / f| ≤ 5.25; 6.85 ≤ f9 / f1 ≤ 18.40; -4.90 ≤ f1 / f ≤ -3.45; -1.8 ≤ f12 / f ≤ -1.25; -2.8 ≤ f2 / R22 ≤ -2.05; 1.1 ≤ f3 / fa ≤ 3.85; 0.65 ≤ |f4 / fa| ≤ 1.8; 0.05 ≤ |(R42+R51) / ( R42-R51)|≤0.6; 0.4≤f4 / f5≤1.3; 2≤|f67| / fb≤7.9; -1.7≤f6 / f7≤-0.85; 1.1≤(Vd6-Vd7) / |f67|≤6.95 ;2.6≤f8 / f≤3.8; 2.74≤f8 / f≤3.8; 0.35≤|f8 / R82|≤0.85; 2.7≤fb / f≤3.25; 0.8≤|fa / fb|≤1.65; 1.7° / mm 2 ≤FOV / H / D≤1.9° / mm 2 ;4.9≤D / H≤5.45; 1.25≤BFL / f≤1.45; -5.35mm 2 ≤f×f1×f4 / |f67|≤-1.75mm 2 Where fa is the effective focal length of the first lens group, f is the total effective focal length of the fixed-focus lens, f9 is the effective focal length of the ninth lens, f1 is the effective focal length of the first lens, f12 is the combined focal length of the first and second lenses, f2 is the effective focal length of the second lens, R22 is the radius of curvature of the image-side surface of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, R42 is the radius of curvature of the image-side surface of the fourth lens, R51 is the radius of curvature of the object-side surface of the fifth lens, and f67 is... The combined focal length of the sixth and seventh lenses, fb is the effective focal length of the second lens group, f6 is the effective focal length of the sixth lens, f7 is the effective focal length of the seventh lens, Vd6 is the Abbe number of the sixth lens, Vd7 is the Abbe number of the seventh lens, f8 is the effective focal length of the eighth lens, R82 is the radius of curvature of the image side of the eighth lens, FOV is the maximum field of view of the fixed focal length lens, H is the image height corresponding to the maximum field of view of the fixed focal length lens, D is the maximum aperture of the fixed focal length lens, and BFL is the back focal length of the fixed focal length lens. Attached Figure Description

[0030] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. In the drawings:

[0031] Figure 1 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 1 of this application is shown;

[0032] Figure 2 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 2 of this application is shown;

[0033] Figure 3 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 3 of this application is shown;

[0034] Figure 4 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 4 of this application is shown;

[0035] Figure 5 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 5 of this application is shown;

[0036] Figure 6 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 6 of this application is shown;

[0037] Figure 7 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 7 of this application is shown;

[0038] Figure 8 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 8 of this application is shown. Detailed Implementation

[0039] To better understand this application, various aspects of this application will be described in detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely descriptions of exemplary embodiments of this application and are not intended to limit the scope of this application in any way.

[0040] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not drawn strictly to scale.

[0041] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane is called the image-side surface of the lens.

[0042] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprises," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. It should be noted that the longitudinal direction stated herein is perpendicular to the optical axis.

[0043] Unless otherwise specified, all terms used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Terms shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly stated herein.

[0044] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0045] A fixed-focus lens according to an exemplary embodiment of this application may include a first lens group and a second lens group. The first lens group may include a first lens, a second lens, a third lens, and a fourth lens. The second lens group may include a fifth lens, a sixth lens, a seventh lens, and an eighth lens. These eight lenses are arranged sequentially along the optical axis from the object side to the image side.

[0046] In an exemplary embodiment, the fixed-focus lens may further include a ninth lens, which may be located on the object side of the first lens.

[0047] In an exemplary embodiment, the ninth lens may have negative optical power. The object-side surface of the ninth lens may be convex, and the image-side surface may be concave. The ninth lens is a negative lens, and its convex-concave shape facilitates the collection of incident light from the object side, reduces the angle of incidence of the incident light on the object-side surface of the first lens, and allows the light to smoothly enter the rear optical system, effectively correcting system aberrations. As an example, the ninth lens is made of glass, which can act as a protective cover, thereby protecting the fixed-focus lens.

[0048] In an exemplary embodiment, the first lens may have negative optical power. The object-side surface of the first lens may be convex, and the image-side surface may be concave. By setting the first lens as a negative lens and setting the first lens to be convex and concave, large-angle light can smoothly enter the rear system, and the incident angle of light on the object-side surface of the second lens is reduced, effectively avoiding aberrations caused by excessive incident angles in subsequent lenses, and improving the resolving power of the fixed-focus lens.

[0049] In an exemplary embodiment, the second lens may have a negative optical power. The object-side surface of the second lens may be convex, and the image-side surface may be concave. By setting the optical power of the second lens to be negative and setting the second lens to be convex and concave, it is beneficial to control the direction of light, so that the light smoothly transitions to the rear optical system, better corrects aberrations in the central field of view, and improves the resolving power of the fixed-focus lens. As an example, the second lens may be an aspherical lens.

[0050] In an exemplary embodiment, the third lens and the fourth lens may be cemented together to form a cemented lens.

[0051] In an exemplary embodiment, the third lens may have a negative optical power. The object-side surface of the third lens is concave. By setting the optical power of the third lens to be negative and the object-side surface to be concave, the third lens can be used in conjunction with the fourth lens, which has a positive optical power, to better correct the spherical aberration of the fixed-focus lens and improve the resolving power of the fixed-focus lens. As an example, the image-side surface of the third lens may be flat, concave, or concave.

[0052] In an exemplary embodiment, the fourth lens may have positive optical power. The image-side surface of the fourth lens may be convex. The fourth lens can be configured as a positive lens, and the image-side surface can be convex, enabling the fourth lens to cooperate with the third lens, which has negative optical power, to effectively correct spherical aberration in a fixed-focus lens; simultaneously, it can also cooperate with the fifth lens behind it to effectively correct axial chromatic aberration in a fixed-focus lens, achieving a large aperture for the fixed-focus lens. As an example, the aperture value FNO of the fixed-focus lens is ≤1.8, and further, FNO = 1.3. As an example, the object-side surface of the fourth lens may be flat, convex, or concave. As an example, the fourth lens may be a glass lens.

[0053] In an exemplary embodiment, the fifth lens may have positive optical power. The object-side surface of the fifth lens may be convex, and the image-side surface may be convex or concave. By setting the fifth lens as a positive lens and its object-side surface as convex, it is beneficial to correct the residual astigmatism and axial chromatic aberration generated by the first lens group. As an example, the fifth lens is an aspherical lens, which can effectively correct the residual astigmatism and axial chromatic aberration of the front lens. As an example, the fifth lens is a spherical lens and uses a thermally stable material, which is beneficial to achieve thermal compensation of the fixed-focus lens.

[0054] In an exemplary embodiment, the sixth lens and the seventh lens may be cemented together to form a cemented lens.

[0055] In an exemplary embodiment, the sixth lens may have positive optical power. The object-side surface of the sixth lens may be convex, and the image-side surface may also be convex. By setting the sixth lens as a biconvex positive lens, and cementing the sixth lens with the seventh lens to form a cemented doublet lens, it is beneficial to achieve smooth light transmission, reduce the tolerance sensitivity of the sixth lens, and improve the production yield of the fixed-focus lens. As an example, the sixth lens may be made of a material with low refractive index and high Abbe number, effectively correcting the transverse chromatic aberration of the fixed-focus lens and improving the image quality of the fixed-focus lens.

[0056] In an exemplary embodiment, the seventh lens may have negative optical power. The object-side surface of the seventh lens may be concave, and the image-side surface may be convex or concave. By setting the seventh lens as a negative lens concave to the object side, and cementing the seventh lens with the sixth lens to form a cemented doublet lens, it is beneficial to achieve smooth light transmission, reduce the tolerance sensitivity of the seventh lens, and improve the production yield of the fixed-focus lens; at the same time, it can also effectively correct the transverse chromatic aberration of the fixed-focus lens and improve the imaging quality of the fixed-focus lens.

[0057] In an exemplary embodiment, the eighth lens may have positive optical power. The object-side surface of the eighth lens may be convex, and the image-side surface may be convex or concave. By setting the eighth lens as a positive lens convex to the object side, the direction of light can be effectively controlled, and the exit angle of light passing through the eighth lens can be reduced, thereby reducing the chief ray angle (CRA) of the fixed-focus lens, which is beneficial for better matching the chip, for example, better matching the CRA curve of the chip.

[0058] In an exemplary embodiment, the fixed-focus lens may further include an aperture stop. The aperture stop may be located between the fourth lens and the fifth lens. By setting an aperture stop, it is beneficial to concentrate light rays, reduce the rear aperture of the fixed-focus lens, reduce the assembly stability of the fixed-focus lens, and improve the image quality of the fixed-focus lens.

[0059] In an exemplary embodiment, the fixed-focus lens may further include a filter for correcting color deviation.

[0060] In an exemplary embodiment, the image height H corresponding to the maximum field of view of the fixed-focus lens can be 4.5mm to 4.7mm, and further, H can be 4.6mm.

[0061] In an exemplary embodiment, at least one of the second, third, fourth, fifth, and eighth lenses has an aspherical surface on its object-side side and / or image-side side. Aspherical surfaces have better radius of curvature characteristics, offering advantages in improving distortion aberrations and general aberrations. Using aspherical surfaces can minimize aberrations that occur during imaging, thereby improving the resolving power of a fixed-focus lens.

[0062] In an exemplary embodiment, any one of the first to eighth lenses can be a glass lens or a plastic lens. A glass lens can effectively suppress the shift in the back focal length of a fixed-focus lens due to temperature changes, improving the stability of the fixed-focus lens. Simultaneously, a glass lens can effectively avoid image blurring caused by high or low temperature environments, ensuring the normal use of the fixed-focus lens, and better correcting system chromatic aberration, thus improving the resolving power of the fixed-focus lens. A plastic lens can effectively reduce the cost of a fixed-focus lens. As an example, if any one of the first to eighth lenses is a glass lens, it is beneficial to improve the image quality and reliability of the fixed-focus lens; for example, when all eight lenses are glass lenses, the fixed-focus lens has a wider operating temperature range and can maintain stable optical performance within the range of -40℃ to 85℃. As an example, if some of the lenses in the first to eighth lenses are glass lenses and the remaining lenses are plastic lenses, the use of a glass-plastic hybrid form for the fixed-focus lens can effectively reduce the cost of the fixed-focus lens.

[0063] In an exemplary embodiment, the effective focal length fa of the first lens group and the total effective focal length f of the fixed-focus lens satisfy the condition: 2.5 ≤ |fa / f| ≤ 6. In one example, 2.5 ≤ |fa / f| ≤ 5.25. Reasonably constraining the ratio of the effective focal length of the first lens group to the total effective focal length of the fixed-focus lens allows the image principal plane of the fixed-focus lens to be closer to the imaging plane, which is beneficial for achieving the reverse telephoto effect of the fixed-focus lens, increasing the back focal length of the fixed-focus lens, and facilitating the assembly of the fixed-focus lens module. Furthermore, increasing the back focal length of the fixed-focus lens also helps reduce the energy of ghost images caused by central reflections from the lens and color filters, thus improving the image quality of the fixed-focus lens.

[0064] In an exemplary embodiment, the effective focal length f9 of the ninth lens and the effective focal length f1 of the first lens can satisfy: 6.5 ≤ f9 / f1 ≤ 19.7. In one example, 6.85 ≤ f9 / f1 ≤ 18.4. Properly configuring the ratio of the effective focal length of the ninth lens to that of the first lens facilitates the entry of large-angle incident light into the fixed-focus lens, which is beneficial for expanding the field of view of the fixed-focus lens, for example, FOV ≥ 196°; at the same time, it can effectively avoid the generation of aberrations.

[0065] In an exemplary embodiment, the effective focal length f1 of the first lens and the total effective focal length f of the fixed-focus lens can satisfy: -5 ≤ f1 / f ≤ -3. In one example, -4.9 ≤ f1 / f ≤ -3.45. Properly configuring the ratio of the effective focal length of the first lens to the total effective focal length of the fixed-focus lens allows large-angle light rays to smoothly enter the rear optical system, reduces the incident angle of light on the object side of the second lens, effectively avoids advanced aberrations caused by excessively large incident angles in subsequent lenses, and improves the resolving performance of the fixed-focus lens.

[0066] In an exemplary embodiment, the combined focal length f12 of the first and second lenses and the total effective focal length f of the fixed-focus lens can satisfy: -2.2 ≤ f12 / f ≤ -1.2. In one example, -1.8 ≤ f12 / f ≤ -1.25. By rationally configuring the ratio of the combined focal length of the first and second lenses to the total effective focal length of the fixed-focus lens, the direction of light can be effectively controlled. Furthermore, the first and second lenses as a whole diverge the light, which is beneficial for maximizing the entry of large-angle light rays into the rear optical system, thereby improving the relative illumination of the fixed-focus lens.

[0067] In an exemplary embodiment, the effective focal length f2 of the second lens and the radius of curvature R22 of the image-side surface of the second lens can satisfy: -3.3 ≤ f2 / R22 ≤ -1.96. In one example, -2.8 ≤ f2 / R22 ≤ -2.05. Properly configuring the ratio of the effective focal length of the second lens to the radius of curvature of the image-side surface of the second lens is beneficial for controlling the light path, ensuring smooth light incidence on the object-side surface of the third lens, reducing the tolerance sensitivity of the fixed-focus lens, and simultaneously correcting aberrations in the central field of view, thereby improving the resolving power of the fixed-focus lens.

[0068] In an exemplary embodiment, the effective focal length f3 of the third lens and the effective focal length fa of the first lens group can satisfy: 1 ​​≤ f3 / fa ≤ 4. In one example, 1.1 ≤ f3 / fa ≤ 3.85. Properly configuring the ratio of the effective focal length of the third lens to the effective focal length of the first lens group is beneficial for correcting spherical aberration in fixed-focus lenses and improving their resolving power.

[0069] In an exemplary embodiment, the effective focal length f4 of the fourth lens and the effective focal length fa of the first lens group can satisfy: 0.52 ≤ |f4 / fa| ≤ 1.87. In one example, 0.65 ≤ |f4 / fa| ≤ 1.8. Properly configuring the ratio of the effective focal length of the fourth lens to the effective focal length of the first lens group is beneficial for correcting spherical aberration and on-axis chromatic aberration in fixed-focus lenses, thereby improving the resolving power of the fixed-focus lens.

[0070] In an exemplary embodiment, the radius of curvature R42 of the image-side surface of the fourth lens and the radius of curvature R51 of the object-side surface of the fifth lens can satisfy: |(R42+R51) / (R42-R51)|≤0.7. In one example, 0.05≤|(R42+R51) / (R42-R51)|≤0.6. Properly configuring the relationship between the radius of curvature of the image-side surface of the fourth lens and the radius of curvature of the object-side surface of the fifth lens is beneficial for controlling the shape of the two lenses on both sides of the aperture stop, controlling the light path, achieving a smooth transition of light, effectively reducing the tolerance sensitivity of the fixed-focus lens, and improving the production yield of the fixed-focus lens.

[0071] In an exemplary embodiment, the effective focal length f4 of the fourth lens and the effective focal length f5 of the fifth lens can satisfy: 0.4 ≤ f4 / f5 ≤ 1.5. In one example, 0.4 ≤ f4 / f5 ≤ 1.3. Reasonably allocating the effective focal lengths of the fourth and fifth lenses can effectively correct spherical aberration and on-axis chromatic aberration of the fixed-focus lens, improving its resolving power; it also facilitates achieving a large aperture for the fixed-focus lens; furthermore, it helps to eliminate temperature drift, achieving thermal compensation and ensuring good temperature performance of the fixed-focus lens. As an example, the aperture value FNO of the fixed-focus lens is ≤ 1.8, and further, FNO = 1.3.

[0072] In an exemplary embodiment, the combined focal length f67 of the sixth and seventh lenses and the effective focal length fb of the second lens group can satisfy: 2 ≤ |f67| / fb ≤ 8. In one example, 2 ≤ |f67| / fb ≤ 7.9. Properly configuring the ratio of the combined focal length of the sixth and seventh lenses to the effective focal length of the second lens group is beneficial for achieving smooth light transmission, reducing the tolerance sensitivity of the sixth and seventh lenses, and improving the production yield of fixed-focus lenses.

[0073] In an exemplary embodiment, the effective focal length f6 of the sixth lens and the effective focal length f7 of the seventh lens can satisfy: -1.86 ≤ f6 / f7 ≤ -0.85. In one example, -1.7 ≤ f6 / f7 ≤ -0.85. Properly configuring the ratio of the effective focal length of the sixth lens to the effective focal length of the seventh lens allows the two positive and negative lenses to complement each other, which helps to balance the astigmatism produced by the lens group behind the aperture stop (e.g., the second lens group) and improve the resolving performance of the fixed-focus lens.

[0074] In an exemplary embodiment, the Abbe number Vd6 of the sixth lens, the Abbe number Vd7 of the seventh lens, and the combined focal length f67 of the sixth and seventh lenses can satisfy: 1 ​​≤ (Vd6 - Vd7) / |f67| ≤ 7. In one example, 1.1 ≤ (Vd6 - Vd7) / |f67| ≤ 6.95. By appropriately selecting the lens materials of the sixth and seventh lenses and controlling the relationship between the Abbe numbers of the sixth and seventh lenses and the combined focal length of the sixth and seventh lenses, the transverse chromatic aberration of the fixed-focus lens can be effectively corrected, the purple fringing of the fixed-focus lens can be effectively avoided, and the image quality of the fixed-focus lens can be improved.

[0075] In an exemplary embodiment, the effective focal length f8 of the eighth lens and the total effective focal length f of the fixed-focus lens can satisfy: 2.6 ≤ f8 / f ≤ 6.05. In one example, 2.6 ≤ f8 / f ≤ 3.8, and further, 2.74 ≤ f8 / f ≤ 3.8. By appropriately configuring the ratio of the effective focal length of the eighth lens to the total effective focal length of the fixed-focus lens, the light trajectory can be effectively controlled, and the deflection angle of the maximum field of view light emitted from the eighth lens can be kept within an appropriate range, thereby ensuring that the fixed-focus lens can better match the chip requirements.

[0076] In an exemplary embodiment, the effective focal length f8 of the eighth lens and the radius of curvature R82 of the image-side surface of the eighth lens can satisfy: |f8 / R82|≤1. In one example, 0.35≤|f8 / R82|≤0.85. Properly configuring the ratio of the effective focal length to the radius of curvature of the image-side surface of the eighth lens can effectively reduce the exit angle of light passing through the eighth lens, thereby reducing the principal angle of the fixed-focus lens. This allows for better matching with the chip and its CRA curve requirements, improving the tolerance and manufacturability of the fixed-focus lens.

[0077] In an exemplary embodiment, the effective focal length fb of the second lens group and the total effective focal length f of the fixed-focus lens can satisfy: 2.7 ≤ fb / f ≤ 3.6. In one example, 2.7 ≤ fb / f ≤ 3.25. Properly configuring the ratio of the effective focal length of the second lens group to the total effective focal length of the fixed-focus lens is beneficial for achieving a large aperture in the fixed-focus lens. As an example, the aperture value FNO of the fixed-focus lens is ≤ 1.8, and further, FNO = 1.3.

[0078] In an exemplary embodiment, the effective focal length fa of the first lens group and the effective focal length fb of the second lens group can satisfy: 0.8 ≤ |fa / fb| ≤ 1.8. In one example, 0.8 ≤ |fa / fb| ≤ 1.65. Properly configuring the ratio of the effective focal length of the first lens group to the effective focal length of the second lens group is beneficial for controlling the overall light path of the fixed-focus lens, achieving a smooth light transition, reducing the sensitivity of the fixed-focus lens, and improving the image quality of the fixed-focus lens.

[0079] In an exemplary embodiment, the maximum field of view (FOV) of the fixed-focus lens, the image height (H) corresponding to the maximum field of view of the fixed-focus lens, and the maximum aperture (D) of the fixed-focus lens can satisfy: 1.65° / mm 2 ≤FOV / H / D≤2.2° / mm 2 In one example, 1.7° / mm 2 ≤FOV / H / D≤1.9° / mm 2By rationally configuring the relationship between the maximum field of view (FOV) of a fixed-focus lens, the image height corresponding to the maximum FOV, and the maximum aperture of the fixed-focus lens, the viewpoint position of the fixed-focus lens can be effectively controlled, ensuring that the maximum aperture meets design requirements. Furthermore, with a fixed image height, the shorter the focal length of the fixed-focus lens, the larger the maximum FOV, and vice versa. By controlling FOV / H / D, a reasonable maximum FOV can be ensured for different sensors. It should be noted that the maximum aperture of a fixed-focus lens can be considered the effective aperture of the object-side surface of the first lens at the maximum FOV.

[0080] In an exemplary embodiment, the image height H corresponding to the maximum field of view of the fixed-focus lens and the maximum aperture D of the fixed-focus lens can satisfy: 4.8 ≤ D / H ≤ 5.5. In one example, 4.9 ≤ D / H ≤ 5.45. Reasonably configuring the ratio of the image height corresponding to the maximum field of view of the fixed-focus lens to the maximum aperture of the fixed-focus lens is beneficial for reducing the front aperture of the fixed-focus lens, thereby achieving vertical miniaturization of the fixed-focus lens. It should be noted that the maximum aperture of the fixed-focus lens can be the effective aperture of the object-side surface of the first lens at the maximum field of view.

[0081] In an exemplary embodiment, the total optical length (TTL) of the fixed-focus lens and its maximum aperture (D) can satisfy the condition: 0.9 ≤ TTL / D ≤ ​​1. A reasonable configuration of the ratio of the total optical length to the maximum aperture of the fixed-focus lens is beneficial for achieving a compact design and miniaturization of the lens. It should be noted that the maximum aperture of the fixed-focus lens can be the effective aperture of the object-side surface of the first lens at its maximum field of view.

[0082] In an exemplary embodiment, the back focal length (BFL) of the fixed-focus lens and the total effective focal length (f) of the fixed-focus lens can satisfy: 1.23 ≤ BFL / f ≤ 1.59. In one example, 1.25 ≤ BFL / f ≤ 1.45. By rationally configuring the ratio of the back focal length to the total effective focal length of the fixed-focus lens while achieving miniaturization, the back focal length of the fixed-focus lens can be made longer. This allows for more space to be reserved for the installation of other optical components, facilitates the assembly of the fixed-focus lens, avoids interference between optical components, and improves the assembly yield of the fixed-focus lens.

[0083] In an exemplary embodiment, the total effective focal length f of the fixed-focus lens, the effective focal length f1 of the first lens, the effective focal length f4 of the fourth lens, and the combined focal length f67 of the sixth and seventh lenses can satisfy: -5.9 ≤ f × ​​f1 × f4 / |f67| ≤ -1.4. In one example, -5.35mm 2 ≤f×f1×f4 / |f67|≤-1.75mm 2The first, fourth, sixth, and seventh lenses are made of glass, and the relationship between the total effective focal length of the fixed-focus lens, the effective focal length of the first lens, the effective focal length of the fourth lens, and the combined focal length of the sixth and seventh lenses is rationally configured. This effectively corrects chromatic aberration produced by the fixed-focus lens, improves the resolving power of the fixed-focus lens, and also suppresses the imaging shift caused by temperature changes, thereby improving the stability and quality of the fixed-focus lens.

[0084] The fixed-focus lens according to the above embodiments of this application can employ multiple lenses. By rationally allocating the optical power, surface shape, and optical parameters of each lens, at least one of the following characteristics of the optical system can be achieved: large field of view, large aperture, high resolution, high illumination, and low cost. The fixed-focus lens provided by this application has the characteristic of a large field of view, such as FOV ≥ 196°, which can capture a wider range of targets, and also has the characteristic of high resolution, such as a fixed-focus lens with 25 million pixels.

[0085] However, those skilled in the art should understand that, without departing from the technical solutions claimed in this application, the number of lenses constituting a fixed-focus lens can be changed to obtain the various results and advantages described in this specification.

[0086] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of a fixed-focus lens applicable to the above-described embodiments.

[0087] Example 1

[0088] The following is for reference Figure 1 A fixed-focus lens according to Embodiment 1 of this application is described. Figure 1 This is a schematic diagram of the fixed-focus lens according to Embodiment 1 of this application.

[0089] like Figure 1 As shown, the fixed-focus lens includes a first lens group and a second lens group sequentially along the optical axis from the object side to the image side. The first lens group includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The second lens group includes a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. The fixed-focus lens also includes a ninth lens L9 positioned between the object side and the first lens. The aperture stop STO is positioned between the fourth lens L4 and the fifth lens L5. The sixth lens L6 and the seventh lens L7 are cemented together to form a cemented lens, such as a cemented doublet lens.

[0090] The ninth lens L9 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0091] The first lens L1 has negative optical power, its object side S3 is convex, and its image side S4 is concave.

[0092] The second lens L2 has negative optical power, with its object side S5 being convex and its image side S6 being concave.

[0093] The third lens L3 has negative optical power, and its object side S7 is concave, as is its image side S8.

[0094] The fourth lens L4 has positive optical power, and its object side S9 is convex, and its image side S10 is convex.

[0095] The fifth lens L5 has positive optical power, and its object side S12 is convex, and its image side S13 is convex.

[0096] The sixth lens L6 has positive optical power, and its object-side surface S14 is convex, as is its image-side surface.

[0097] The seventh lens L7 has negative optical power, and its object side S15 is concave, and its image side S16 is concave.

[0098] The eighth lens L8 has positive optical power, and its object side S17 is convex, and its image side S18 is convex.

[0099] A filter CG can also be disposed between the eighth lens L8 and the imaging plane IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object passes sequentially through surfaces S1-S10 and S12-S18 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S10 and S12-S20 are... Figure 1 Not shown in the image.

[0100] Table 1 shows the basic parameters of the fixed-focus lens of Example 1, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0101]

[0102]

[0103] Table 1

[0104] In this embodiment, the total effective focal length f of the fixed-focus lens is 1.42mm, and the aperture number Fno is 1.3. The relative illumination of the fixed-focus lens is 70%.

[0105] The object-side surface S5 and image-side surface S6 of the second lens L2, the object-side surface S7 and image-side surface S8 of the third lens L3, the object-side surface S12 and image-side surface S13 of the fifth lens L5, and the object-side surface S17 and image-side surface S18 of the eighth lens L8 are all aspherical. The surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formulas:

[0106]

[0107] Where x is the distance vector from the vertex of the aspherical surface at a height of h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 2 gives the conic coefficient k and the higher-order coefficients A4, A6, A8, A18 that can be used for the aspherical surfaces S5, S6, S7, S8, S12, S13, S17, and S18 in Example 1. 10 A 12 A 14 and A 16 .

[0108] Face number k A4 A6 A8 A10 A12 A14 A16 S5 3.64 8.88E-03 -2.15E-03 2.53E-04 -3.52E-05 2.69E-06 -7.51E-08 0.00E+00 S6 -0.46 2.23E-02 3.15E-03 -3.01E-03 1.31E-03 -2.07E-04 -1.60E-05 4.19E-06 S7 -1.30 2.32E-02 -2.42E-03 3.71E-04 -6.84E-05 4.30E-05 -1.25E-05 9.37E-07 S8 0.00 1.70E-02 -3.78E-03 6.19E-04 4.18E-05 -5.33E-05 8.84E-06 -4.71E-07 S12 -3.11 7.48E-03 1.54E-03 -8.43E-04 4.26E-04 -1.26E-04 2.06E-05 -1.34E-06 S13 0.00 5.02E-03 -7.40E-04 1.59E-03 -8.25E-04 2.76E-04 -5.01E-05 4.15E-06 S17 -4.42 1.10E-02 -1.93E-03 4.83E-04 -8.17E-05 8.79E-06 -4.88E-07 1.19E-08 S18 0.68 1.07E-02 -7.20E-04 3.14E-04 -6.41E-05 7.61E-06 -4.88E-07 1.78E-08

[0109] Table 2

[0110] Example 2

[0111] The following is for reference Figure 2 Describes a fixed-focus lens according to Embodiment 2 of this application. Figure 2 This is a schematic diagram of the fixed-focus lens according to Embodiment 2 of this application.

[0112] like Figure 2 As shown, the fixed-focus lens includes a first lens group and a second lens group sequentially along the optical axis from the object side to the image side. The first lens group includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The second lens group includes a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. The fixed-focus lens also includes a ninth lens L9 positioned between the object side and the first lens. The aperture stop STO is positioned between the fourth lens L4 and the fifth lens L5. The sixth lens L6 and the seventh lens L7 are cemented together to form a cemented lens, such as a cemented doublet lens.

[0113] The ninth lens L9 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0114] The first lens L1 has negative optical power, its object side S3 is convex, and its image side S4 is concave.

[0115] The second lens L2 has negative optical power, with its object side S5 being convex and its image side S6 being concave.

[0116] The third lens L3 has negative optical power, and its object side S7 is concave, as is its image side S8.

[0117] The fourth lens L4 has positive optical power, and its object side S9 is convex, and its image side S10 is convex.

[0118] The fifth lens L5 has positive optical power, with its object side S12 being convex and its image side S13 being concave.

[0119] The sixth lens L6 has positive optical power, and its object-side surface S14 is convex, as is its image-side surface.

[0120] The seventh lens L7 has negative optical power, and its object side S15 is concave, and its image side S16 is concave.

[0121] The eighth lens L8 has positive optical power, and its object side S17 is convex, and its image side S18 is convex.

[0122] A filter CG can also be disposed between the eighth lens L8 and the imaging plane IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object passes sequentially through surfaces S1-S10 and S12-S18 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S10 and S12-S20 are... Figure 2 Not shown in the image.

[0123] Table 3 shows the basic parameters of the fixed-focus lens in Example 2, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0124]

[0125] Table 3

[0126] In this embodiment, the total effective focal length f of the fixed-focus lens is 1.43mm, and the aperture number Fno is 1.3. The relative illumination of the fixed-focus lens is 70%.

[0127] The object-side surface S5 and image-side surface S6 of the second lens L2, the object-side surface S7 and image-side surface S8 of the third lens L3, the object-side surface S12 and image-side surface S13 of the fifth lens L5, and the object-side surface S17 and image-side surface S18 of the eighth lens L8 are all aspherical surfaces. Table 4 gives the conic coefficient k and higher-order coefficients A4, A6, A8, and A6 of each aspherical surface S5, S6, S7, S8, S12, S13, S17, and S18 that can be used in Example 2. 10 A 12 A 14 and A 16 .

[0128] Face number k A4 A6 A8 A10 A12 A14 A16 S5 3.62 8.83E-03 -2.15E-03 2.53E-04 -3.52E-05 2.69E-06 -7.49E-08 0.00E+00 S6 -0.46 2.25E-02 3.16E-03 -3.01E-03 1.31E-03 -2.07E-04 -1.61E-05 4.17E-06 S7 -1.38 2.34E-02 -2.37E-03 3.79E-04 -6.78E-05 4.30E-05 -1.25E-05 9.36E-07 S8 0.00 1.69E-02 -3.77E-03 6.27E-04 4.31E-05 -5.31E-05 8.83E-06 -4.85E-07 S12 -2.90 7.56E-03 1.52E-03 -8.51E-04 4.25E-04 -1.26E-04 2.06E-05 -1.34E-06 S13 0.00 5.13E-03 -7.11E-04 1.60E-03 -8.25E-04 2.75E-04 -5.02E-05 4.10E-06 S17 -4.33 1.10E-02 -1.94E-03 4.81E-04 -8.18E-05 8.82E-06 -4.87E-07 1.20E-08 S18 0.73 1.05E-02 -7.27E-04 3.13E-04 -6.42E-05 7.60E-06 -4.87E-07 1.82E-08

[0129] Table 4

[0130] Example 3

[0131] The following is for reference Figure 3 Describes a fixed-focus lens according to Embodiment 3 of this application. Figure 3 This is a schematic diagram of the fixed-focus lens according to Embodiment 3 of this application.

[0132] like Figure 3 As shown, the fixed-focus lens includes a first lens group and a second lens group sequentially along the optical axis from the object side to the image side. The first lens group includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The second lens group includes a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. The fixed-focus lens also includes a ninth lens L9 positioned between the object side and the first lens. The aperture stop STO is positioned between the fourth lens L4 and the fifth lens L5. The sixth lens L6 and the seventh lens L7 are cemented together to form a cemented lens, such as a cemented doublet lens.

[0133] The ninth lens L9 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0134] The first lens L1 has negative optical power, its object side S3 is convex, and its image side S4 is concave.

[0135] The second lens L2 has negative optical power, with its object side S5 being convex and its image side S6 being concave.

[0136] The third lens L3 has negative optical power, and its object side S7 is concave, as is its image side S8.

[0137] The fourth lens L4 has positive optical power, and its object side S9 is convex, and its image side S10 is convex.

[0138] The fifth lens L5 has positive optical power, and its object side S12 is convex, and its image side S13 is convex.

[0139] The sixth lens L6 has positive optical power, and its object-side surface S14 is convex, as is its image-side surface.

[0140] The seventh lens L7 has negative optical power, and its object side S15 is concave, and its image side S16 is concave.

[0141] The eighth lens L8 has positive optical power, and its object side S17 is convex, and its image side S18 is convex.

[0142] A filter CG can also be disposed between the eighth lens L8 and the imaging plane IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object passes sequentially through surfaces S1-S10 and S12-S18 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S10 and S12-S20 are... Figure 3 Not shown in the image.

[0143] Table 5 shows the basic parameters of the fixed-focus lens in Example 3, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0144]

[0145]

[0146] Table 5

[0147] In this embodiment, the total effective focal length f of the fixed-focus lens is 1.44mm, and the aperture number Fno is 1.6. The relative illumination of the fixed-focus lens is 73%.

[0148] The object-side surface S5 and image-side surface S6 of the second lens L2, the object-side surface S7 and image-side surface S8 of the third lens L3, the object-side surface S12 and image-side surface S13 of the fifth lens L5, and the object-side surface S17 and image-side surface S18 of the eighth lens L8 are all aspherical surfaces.

[0149] Table 6 provides the conic coefficient k and higher-order coefficients A4, A6, A8, A12, S13, S17, and S18 for each aspherical surface S5, S6, S7, S8, S12, S13, S17, and S18 in Example 3. 10 A 12 A 14 and A 16 .

[0150] Face number k A4 A6 A8 A10 A12 A14 A16 S5 3.04 8.68E-03 -2.14E-03 2.58E-04 -3.45E-05 2.73E-06 -8.02E-08 0.00E+00 S6 -0.40 2.16E-02 3.93E-03 -2.95E-03 1.26E-03 -2.26E-04 -1.85E-05 4.40E-06 S7 -2.94 2.48E-02 -3.34E-03 4.53E-04 -5.98E-05 3.59E-05 -1.46E-05 5.22E-07 S8 27.16 2.10E-02 -4.81E-03 7.35E-04 3.44E-05 -6.79E-05 5.89E-06 6.58E-07 S12 -3.18 8.66E-03 2.30E-03 -6.94E-04 4.42E-04 -1.28E-04 1.97E-05 -1.02E-06 S13 0.00 5.55E-03 4.53E-04 1.80E-03 -8.39E-04 2.71E-04 -4.77E-05 5.02E-06 S17 -4.55 1.04E-02 -2.03E-03 4.66E-04 -8.25E-05 9.32E-06 -3.90E-07 0.00E+00 S18 1.13 8.45E-03 -6.65E-04 3.09E-04 -6.63E-05 7.21E-06 -4.96E-07 4.41E-08

[0151] Table 6

[0152] Example 4

[0153] The following is for reference Figure 4 A fixed-focus lens according to Embodiment 4 of this application is described. Figure 4 This is a schematic diagram of the fixed-focus lens according to Embodiment 4 of this application.

[0154] like Figure 4 As shown, the fixed-focus lens includes a first lens group and a second lens group sequentially along the optical axis from the object side to the image side. The first lens group includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The second lens group includes a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. The fixed-focus lens also includes a ninth lens L9 positioned between the object side and the first lens. The aperture stop STO is positioned between the fourth lens L4 and the fifth lens L5. The sixth lens L6 and the seventh lens L7 are cemented together to form a cemented lens, such as a cemented doublet lens.

[0155] The ninth lens L9 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0156] The first lens L1 has negative optical power, its object side S3 is convex, and its image side S4 is concave.

[0157] The second lens L2 has negative optical power, with its object side S5 being convex and its image side S6 being concave.

[0158] The third lens L3 has negative optical power, and its object side S7 is concave, as is its image side S8.

[0159] The fourth lens L4 has positive optical power, and its object side S9 is convex, and its image side S10 is convex.

[0160] The fifth lens L5 has positive optical power, and its object side S12 is convex, and its image side S13 is convex.

[0161] The sixth lens L6 has positive optical power, and its object-side surface S14 is convex, as is its image-side surface.

[0162] The seventh lens L7 has negative optical power, and its object side S15 is concave, and its image side S16 is concave.

[0163] The eighth lens L8 has positive optical power, and its object side S17 is convex, and its image side S18 is convex.

[0164] A filter CG can also be disposed between the eighth lens L8 and the imaging plane IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object passes sequentially through surfaces S1-S10 and S12-S18 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S10 and S12-S20 are... Figure 4 Not shown in the image.

[0165] Table 7 shows the basic parameters of the fixed-focus lens in Example 4, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0166]

[0167] Table 7

[0168] In this embodiment, the total effective focal length f of the fixed-focus lens is 1.45mm, and the aperture number Fno is 1.8. The relative illumination of the fixed-focus lens is 74%.

[0169] The object-side surface S5 and image-side surface S6 of the second lens L2, the object-side surface S7 and image-side surface S8 of the third lens L3, the object-side surface S12 and image-side surface S13 of the fifth lens L5, and the object-side surface S17 and image-side surface S18 of the eighth lens L8 are all aspherical surfaces. Table 8 gives the conic coefficient k and higher-order coefficients A4, A6, A8, and A6 of each aspherical surface S5, S6, S7, S8, S12, S13, S17, and S18 that can be used in Example 4. 10 A 12 A 14 and A 16 .

[0170] Face number k A4 A6 A8 A10 A12 A14 A16 S5 -4.06 8.46E-03 -2.18E-03 2.60E-04 -3.38E-05 2.74E-06 -8.24E-08 0.00E+00 S6 -0.53 2.08E-02 2.00E-03 -2.45E-03 1.15E-03 -2.15E-04 -1.62E-05 4.85E-06 S7 -0.37 2.65E-02 -3.34E-03 5.50E-04 -6.45E-05 2.17E-05 -1.52E-05 1.63E-06 S8 18.50 2.17E-02 -4.52E-03 8.25E-04 -6.88E-06 -8.27E-05 1.62E-05 -7.78E-07 S12 -1.64 9.76E-03 2.43E-03 -5.59E-04 4.91E-04 -1.24E-04 1.68E-05 -1.83E-06 S13 0.00 7.49E-03 1.05E-03 1.78E-03 -8.32E-04 3.01E-04 -3.96E-05 1.45E-06 S17 -4.55 1.05E-02 -2.01E-03 4.71E-04 -8.16E-05 9.35E-06 -3.98E-07 0.00E+00 S18 1.47 7.97E-03 -5.54E-04 3.00E-04 -6.68E-05 7.32E-06 -4.84E-07 5.06E-08

[0171] Table 8

[0172] Example 5

[0173] The following is for reference Figure 5 A fixed-focus lens according to Embodiment 5 of this application is described. Figure 5 This is a schematic diagram of the structure of a fixed-focus lens according to Embodiment 5 of this application.

[0174] like Figure 5 As shown, the fixed-focus lens includes a first lens group and a second lens group sequentially along the optical axis from the object side to the image side. The first lens group includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The second lens group includes a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. The fixed-focus lens also includes a ninth lens L9 positioned between the object side and the first lens. The aperture stop STO is positioned between the fourth lens L4 and the fifth lens L5. The sixth lens L6 and the seventh lens L7 are cemented together to form a cemented lens, such as a cemented doublet lens.

[0175] The ninth lens L9 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0176] The first lens L1 has negative optical power, its object side S3 is convex, and its image side S4 is concave.

[0177] The second lens L2 has negative optical power, with its object side S5 being convex and its image side S6 being concave.

[0178] The third lens L3 has negative optical power, and its object side S7 is concave, as is its image side S8.

[0179] The fourth lens L4 has positive optical power, and its object side S9 is convex, and its image side S10 is convex.

[0180] The fifth lens L5 has positive optical power, with its object side S12 being convex and its image side S13 being concave.

[0181] The sixth lens L6 has positive optical power, and its object-side surface S14 is convex, as is its image-side surface.

[0182] The seventh lens L7 has negative optical power, and its object side S15 is concave, and its image side S16 is concave.

[0183] The eighth lens L8 has positive optical power, and its object side S17 is convex, and its image side S18 is convex.

[0184] A filter CG can also be disposed between the eighth lens L8 and the imaging plane IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object passes sequentially through surfaces S1-S10 and S12-S18 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S10 and S12-S20 are... Figure 5 Not shown in the image.

[0185] Table 9 shows the basic parameters of the fixed-focus lens of Example 5, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0186]

[0187]

[0188] Table 9

[0189] In this embodiment, the total effective focal length f of the fixed-focus lens is 1.44mm, and the aperture number Fno is 1.8. The relative illumination of the fixed-focus lens is 70%.

[0190] The object-side surface S5 and image-side surface S6 of the second lens L2, the object-side surface S7 and image-side surface S8 of the third lens L3, the object-side surface S12 and image-side surface S13 of the fifth lens L5, and the object-side surface S17 and image-side surface S18 of the eighth lens L8 are all aspherical surfaces. Table 10 gives the conic coefficient k and higher-order coefficients A4, A6, A8, and A6 of each aspherical surface S5, S6, S7, S8, S12, S13, S17, and S18 that can be used in Example 5. 10 A 12 A 14 and A 16 .

[0191] Face number k A4 A6 A8 A10 A12 A14 A16 S5 -4.05 8.45E-03 -2.19E-03 2.59E-04 -3.38E-05 2.75E-06 -8.24E-08 0.00E+00 S6 -0.50 2.10E-02 2.07E-03 -2.45E-03 1.13E-03 -2.15E-04 -1.73E-05 5.18E-06 S7 -1.04 2.61E-02 -3.53E-03 6.28E-04 -5.21E-05 2.27E-05 -1.51E-05 1.51E-06 S8 1.01 2.11E-02 -4.37E-03 8.52E-04 1.41E-05 -7.93E-05 1.53E-05 -9.67E-07 S12 -1.13 1.03E-02 2.19E-03 -5.47E-04 4.98E-04 -1.24E-04 1.58E-05 -2.01E-06 S13 0.00 8.83E-03 1.02E-03 1.86E-03 -7.89E-04 3.02E-04 -4.10E-05 8.37E-07 S17 -4.38 1.04E-02 -2.04E-03 4.70E-04 -8.08E-05 9.49E-06 -4.36E-07 0.00E+00 S18 1.50 7.76E-03 -5.58E-04 3.00E-04 -6.67E-05 7.32E-06 -4.88E-07 5.01E-08

[0192] Table 10

[0193] Example 6

[0194] The following is for reference Figure 6 A fixed-focus lens according to Embodiment 6 of this application is described. Figure 6 This is a schematic diagram of the fixed-focus lens according to Embodiment 6 of this application.

[0195] like Figure 6 As shown, the fixed-focus lens includes a first lens group and a second lens group sequentially along the optical axis from the object side to the image side. The first lens group includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The second lens group includes a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. The fixed-focus lens also includes a ninth lens L9 positioned between the object side and the first lens. The aperture stop STO is positioned between the fourth lens L4 and the fifth lens L5. The sixth lens L6 and the seventh lens L7 are cemented together to form a cemented lens, such as a cemented doublet lens.

[0196] The ninth lens L9 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0197] The first lens L1 has negative optical power, its object side S3 is convex, and its image side S4 is concave.

[0198] The second lens L2 has negative optical power, with its object side S5 being convex and its image side S6 being concave.

[0199] The third lens L3 has negative optical power, and its object side S7 is concave, as is its image side S8.

[0200] The fourth lens L4 has positive optical power, and its object side S9 is convex, and its image side S10 is convex.

[0201] The fifth lens L5 has positive optical power, and its object side S12 is convex, and its image side S13 is convex.

[0202] The sixth lens L6 has positive optical power, and its object-side surface S14 is convex, as is its image-side surface.

[0203] The seventh lens L7 has negative optical power, and its object side S15 is concave, and its image side S16 is concave.

[0204] The eighth lens L8 has positive optical power, and its object side S17 is convex, and its image side S18 is convex.

[0205] A filter CG can also be disposed between the eighth lens L8 and the imaging plane IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object passes sequentially through surfaces S1-S10 and S12-S18 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S10 and S12-S20 are... Figure 6 Not shown in the image.

[0206] Table 11 shows the basic parameters of the fixed-focus lens of Example 6, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0207]

[0208] Table 11

[0209] In this embodiment, the total effective focal length f of the fixed-focus lens is 1.6mm, and the aperture number Fno is 1.8. The relative illumination of the fixed-focus lens is 70%.

[0210] The object-side surface S5 and image-side surface S6 of the second lens L2, the object-side surface S7 and image-side surface S8 of the third lens L3, the object-side surface S9 and image-side surface S10 of the fourth lens L4, the object-side surface S12 and image-side surface S13 of the fifth lens L5, and the object-side surface S17 and image-side surface S18 of the eighth lens L8 are all aspherical surfaces. Table 12 gives the conic coefficient k and higher-order coefficients A4, A6, A8, and A6 of each aspherical surface S5, S6, S7, S8, S9, S10, S12, S13, S17, and S18 that can be used in Example 6. 10 A 12 A 14 and A 16 .

[0211] Face number k A4 A6 A8 A10 A12 A14 A16 S5 0.00 -1.35E-03 6.57E-05 -2.16E-06 -9.95E-07 5.82E-08 0.00E+00 0.00E+00 S6 -0.39 9.71E-03 2.61E-03 -6.48E-04 2.26E-04 2.94E-05 -1.31E-05 -6.61E-07 S7 -0.07 1.65E-04 3.88E-05 1.11E-05 1.79E-06 -9.05E-08 0.00E+00 0.00E+00 S8 0.00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S9 0.68 3.36E-03 -5.94E-05 6.24E-05 -2.02E-05 -1.22E-06 -8.96E-08 0.00E+00 S10 -26.13 9.90E-04 4.12E-04 1.53E-05 -3.75E-06 3.62E-07 -6.18E-07 0.00E+00 S12 -1.88 5.32E-03 -2.46E-04 1.28E-04 -1.45E-05 3.00E-06 -3.52E-07 0.00E+00 S13 -3.10 -3.19E-03 -2.56E-04 5.30E-04 -1.36E-04 1.76E-05 -2.58E-07 0.00E+00 S17 -1.67 -6.21E-03 -8.57E-04 3.21E-04 -8.74E-05 9.33E-07 1.01E-06 -8.31E-09 S18 11.01 -6.46E-03 5.39E-04 -3.85E-04 1.32E-04 -2.65E-05 2.11E-06 1.46E-09

[0212] Table 12

[0213] Example 7

[0214] The following is for reference Figure 7 A fixed-focus lens according to Embodiment 7 of this application is described. Figure 7 This is a schematic diagram of the structure of a fixed-focus lens according to Embodiment 7 of this application.

[0215] like Figure 7 As shown, the fixed-focus lens includes a first lens group and a second lens group sequentially along the optical axis from the object side to the image side. The first lens group includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The second lens group includes a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. The fixed-focus lens also includes a ninth lens L9 positioned between the object side and the first lens. An aperture stop STO is positioned between the fourth lens L4 and the fifth lens L5. The third lens L3 and the fourth lens L4 are cemented together to form a cemented lens, such as a first cemented doublet. The sixth lens L6 and the seventh lens L7 are cemented together to form a cemented lens, such as a second cemented doublet.

[0216] The ninth lens L9 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0217] The first lens L1 has negative optical power, its object side S3 is convex, and its image side S4 is concave.

[0218] The second lens L2 has negative optical power, with its object side S5 being convex and its image side S6 being concave.

[0219] The third lens L3 has negative optical power, its object side S7 is concave, and its image side is flat.

[0220] The fourth lens L4 has positive optical power, with its object side S8 being a plane and its image side S9 being a convex surface.

[0221] The fifth lens L5 has positive optical power, and its object side S11 is convex, and its image side S12 is convex.

[0222] The sixth lens L6 has positive optical power, and its object side S13 is convex, as is its image side.

[0223] The seventh lens L7 has negative optical power, and its object side S14 is concave, and its image side S15 is concave.

[0224] The eighth lens L8 has positive optical power, and its object side S16 is convex, and its image side S17 is convex.

[0225] A filter CG can also be disposed between the eighth lens L8 and the imaging plane IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object passes sequentially through surfaces S1-S10 and S12-S18 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S10 and S12-S20 are... Figure 7 Not shown in the image.

[0226] Table 13 shows the basic parameters of the fixed-focus lens of Example 7, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0227]

[0228]

[0229] Table 13

[0230] In this embodiment, the total effective focal length f of the fixed-focus lens is 1.52mm, and the aperture number Fno is 1.8. The relative illumination of the fixed-focus lens is 71%.

[0231] The object-side surface S5 and image-side surface S6 of the second lens L2, the object-side surface S11 and image-side surface S12 of the fifth lens L5, and the object-side surface S17 and image-side surface S18 of the eighth lens L8 are all aspherical surfaces. Table 14 gives the conic coefficient k and higher-order coefficients A4, A6, A8, and A6 of each aspherical surface S5, S6, S11, S12, S16, and S17 that can be used in Example 7. 10 A 12 A 14 and A 16 .

[0232] Face number k A4 A6 A8 A10 A12 A14 A16 S5 0.00 -6.75E-03 -1.41E-04 5.47E-05 -1.81E-06 -4.75E-08 0.00E+00 0.00E+00 S6 -0.54 7.75E-04 -6.70E-05 -2.56E-04 6.93E-05 -6.06E-06 0.00E+00 0.00E+00 S11 -1.55 3.14E-03 2.39E-04 1.15E-04 -2.78E-05 7.94E-06 8.38E-07 0.00E+00 S12 -1.19 9.88E-04 1.39E-04 2.50E-04 -5.47E-05 3.81E-06 2.89E-06 0.00E+00 S16 -1.04 -2.18E-03 5.71E-05 9.04E-05 -4.74E-05 7.81E-06 -5.82E-07 0.00E+00 S17 37.01 4.89E-03 -2.53E-04 8.79E-05 -1.12E-05 -1.62E-06 2.77E-07 0.00E+00

[0233] Table 14

[0234] Example 8

[0235] The following is for reference Figure 8 Describes a fixed-focus lens according to Embodiment 8 of this application. Figure 8 This is a schematic diagram of the fixed-focus lens according to Embodiment 8 of this application.

[0236] like Figure 8 As shown, the fixed-focus lens includes a first lens group and a second lens group sequentially along the optical axis from the object side to the image side. The first lens group includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The second lens group includes a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. The fixed-focus lens also includes a ninth lens L9 positioned between the object side and the first lens. The aperture stop STO is positioned between the fourth lens L4 and the fifth lens L5. The sixth lens L6 and the seventh lens L7 are cemented together to form a cemented lens, such as a cemented doublet lens.

[0237] The ninth lens L9 has negative optical power, with its object side S1 being convex and its image side S2 being concave.

[0238] The first lens L1 has negative optical power, its object side S3 is convex, and its image side S4 is concave.

[0239] The second lens L2 has negative optical power, with its object side S5 being convex and its image side S6 being concave.

[0240] The third lens L3 has negative optical power, and its object side S7 is concave, as is its image side S8.

[0241] The fourth lens L4 has positive optical power, and its object side S9 is convex, and its image side S10 is convex.

[0242] The fifth lens L5 has positive optical power, with its object side S12 being convex and its image side S13 being concave.

[0243] The sixth lens L6 has positive optical power, and its object-side surface S14 is convex, as is its image-side surface.

[0244] The seventh lens L7 has negative optical power, with its object side S15 being concave and its image side S16 being convex.

[0245] The eighth lens L8 has positive optical power, with its object side S17 being convex and its image side S18 being concave.

[0246] A filter CG can also be disposed between the eighth lens L8 and the imaging plane IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object passes sequentially through surfaces S1-S10 and S12-S18 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1-S10 and S12-S20 are... Figure 8 Not shown in the image.

[0247] Table 15 shows the basic parameters of the fixed-focus lens of Example 8, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0248]

[0249] Table 15

[0250] In this embodiment, the total effective focal length f of the fixed-focus lens is 1.465mm, and the aperture number Fno is 1.8. The relative illumination of the fixed-focus lens is 70%.

[0251] The object-side surface S5 and image-side surface S6 of the second lens L2, the object-side surface S7 and image-side surface S8 of the third lens L3, the object-side surface S12 and image-side surface S13 of the fifth lens L5, and the object-side surface S17 and image-side surface S18 of the eighth lens L8 are all aspherical surfaces.

[0252] Table 16 provides the conic coefficient k and higher-order coefficients A4, A6, A8, A12, S13, S17, and S18 for each aspherical surface S5, S6, S7, S8, S12, S13, S17, and S18 in Example 8. 10 A 12 A 14 and A 16 .

[0253] Face number k A4 A6 A8 A10 A12 A14 A16 S5 -2.81 8.69E-03 -2.16E-03 2.61E-04 -3.37E-05 2.73E-06 -8.44E-08 0.00E+00 S6 -0.45 2.27E-02 2.70E-03 -2.26E-03 1.20E-03 -2.04E-04 -1.55E-05 4.03E-06 S7 -6.12 2.89E-02 -3.46E-03 4.51E-04 -5.22E-05 3.11E-05 -1.07E-05 7.99E-07 S8 17.04 2.31E-02 -4.70E-03 5.51E-04 -1.76E-05 -7.19E-05 1.93E-05 -1.94E-06 S12 1.56 1.23E-02 1.93E-03 -7.76E-04 4.80E-04 -1.14E-04 2.00E-05 -2.51E-06 S13 0.00 1.25E-02 3.75E-04 1.70E-03 -8.35E-04 3.00E-04 -4.03E-05 2.53E-06 S17 -4.81 1.06E-02 -2.20E-03 3.47E-04 -1.03E-04 1.48E-05 -1.13E-06 0.00E+00 S18 0.00 9.52E-03 -7.42E-04 1.76E-04 -8.98E-05 6.55E-06 1.14E-07 -1.32E-09

[0254] Table 16

[0255] In summary, the conditional expressions in Examples 1 to 8 satisfy the relationships shown in Table 17.

[0256] Conditional / Example 1 2 3 4 5 6 7 8 f9 / f1 17.04 17.16 17.57 18.38 18.31 6.87 10.15 17.08 f1 / f -4.81 -4.74 -4.60 -4.37 -4.42 -4.89 -3.48 -4.65 f12 / f -1.69 -1.67 -1.53 -1.55 -1.54 -1.65 -1.26 -1.77 f2 / R22 -2.60 -2.61 -2.44 -2.51 -2.48 -2.20 -2.09 -2.79 f3 / fa 1.91 1.81 1.13 1.25 1.15 1.82 3.81 1.14 |f4 / fa| 1.75 1.49 0.70 0.84 0.72 1.67 1.07 0.95 |(R42+R51) / (R42-R51)| 0.55 0.53 0.17 0.15 0.28 0.38 0.07 0.32 f4 / f5 1.02 0.91 0.60 0.64 0.59 1.26 1.28 0.44 |f67| / fb 6.18 7.89 4.68 5.11 5.21 3.64 2.05 2.46 (Vd6-Vd7) / |f67| 1.45 1.12 2.08 1.91 1.84 4.23 6.90 4.42 f6 / f7 -1.36 -1.33 -1.45 -1.47 -1.42 -1.54 -1.68 -0.86 f8 / f 2.89 2.86 2.78 2.86 2.83 3.24 3.76 6.02 |f8 / R82| 0.76 0.75 0.83 0.79 0.75 0.39 0.36 0.82 |fa / f| 2.55 2.99 5.23 4.39 5.08 2.53 4.06 3.75 fb / f 3.01 3.04 3.11 3.08 3.15 2.80 3.23 2.73 |fa / fb| 0.83 0.96 1.63 1.39 1.57 0.82 1.14 1.37 f×f1×f4 / |f67| -2.32 -1.79 -2.39 -2.15 -2.05 -5.20 -5.28 -5.31 FOV / H / D 1.72 1.71 1.73 1.74 1.75 1.88 1.89 1.73 D / H 5.42 5.43 5.40 5.32 5.33 4.94 4.93 5.38 TTL / D 0.92 0.92 0.91 0.92 0.92 1.00 1.00 0.91 BFL / f 1.44 1.44 1.42 1.41 1.41 1.27 1.34 1.38

[0257] Table 17

[0258] This application also provides an imaging device, wherein the electronic photosensitive element may be a photocoupled device (CCD) or a complementary metal oxide semiconductor device (CMOS), and the imaging device is equipped with the fixed-focus lens described above.

[0259] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A fixed focus lens characterized by, In order from the object side to the image side along the optical axis, the lens includes: a ninth lens having negative refractive power; a first lens group having negative refractive power; and a second lens group having positive refractive power; The first lens group includes, in order from the object side to the image side: a first lens having negative refractive power; a second lens having negative refractive power; a third lens having negative refractive power; a fourth lens having positive refractive power; The second lens group includes, in order from the object side to the image side: a fifth lens having positive refractive power; a sixth lens having positive refractive power; a seventh lens having negative refractive power; an eighth lens having positive refractive power; The fixed focus lens has nine lenses with refractive power. The effective focal length fa of the first lens group and the total effective focal length f of the fixed focus lens satisfy: 2.5 ≤ |fa / f| ≤ 6.

2. The fixed focus lens of claim 1, wherein The object side surface of the ninth lens is a convex surface, and the image side surface is a concave surface.

3. The fixed focus lens according to claim 1, wherein the object side surface of the first lens is a convex surface, and the image side surface is a concave surface; the object side surface of the second lens is a convex surface, and the image side surface is a concave surface; the object side surface of the third lens is a concave surface; the image side surface of the fourth lens is a convex surface; the object side surface of the fifth lens is a convex surface; the object side surface of the sixth lens is a convex surface, and the image side surface is a convex surface; the object side surface of the seventh lens is a concave surface; the object side surface of the eighth lens is a convex surface.

4. The fixed focus lens according to claim 1 or 2, characterized in that, The sixth lens and the seventh lens are cemented to form a cemented lens.

5. The fixed focus lens according to claim 1 or 2, characterized in that, The effective focal length f9 of the ninth lens and the effective focal length f1 of the first lens satisfy: 6.5 ≤ f9 / f1 ≤ 19.

7.

6. The fixed focus lens according to claim 1 or 2, characterized in that, The effective focal length f1 of the first lens and the total effective focal length f of the fixed focus lens satisfy: -5 ≤ f1 / f ≤ -3.

7. The fixed focus lens according to claim 1 or 2, characterized in that, The combined focal length f12 of the first lens and the second lens and the total effective focal length f of the fixed focus lens satisfy: -2.2 ≤ f12 / f ≤ -1.

2.

8. The fixed focus lens according to claim 1 or 2, characterized in that, The effective focal length f2 of the second lens and the radius of curvature R22 of the image side surface of the second lens satisfy: -3.3 ≤ f2 / R22 ≤ -1.

96.

9. The fixed focus lens according to claim 1 or 2, characterized in that, The effective focal length f3 of the third lens and the effective focal length fa of the first lens group satisfy: 1 ≤ f3 / fa ≤ 4.

10. The fixed focus lens according to claim 1 or 2, characterized in that, The effective focal length f4 of the fourth lens and the effective focal length fa of the first lens group satisfy: 0.52 ≤ |f4 / fa| ≤ 1.

87.

11. The fixed focus lens according to claim 1 or 2, characterized in that, The radius of curvature R42 of the image side surface of the fourth lens and the radius of curvature R51 of the object side surface of the fifth lens satisfy: |(R42+R51) / (R42-R51)| ≤ 0.

7.

12. The fixed focus lens according to claim 1 or 2, characterized in that, The effective focal length f4 of the fourth lens and the effective focal length f5 of the fifth lens satisfy: 0.4 ≤ f4 / f5 ≤ 1.

5.

13. The fixed focus lens according to claim 1 or 2, characterized in that, The combined focal length f67 of the sixth lens and the seventh lens and the effective focal length fb of the second lens group satisfy: 2 ≤ |f67| / fb ≤ 8.

14. The fixed focus lens according to claim 1 or 2, characterized in that, The effective focal length f6 of the sixth lens and the effective focal length f7 of the seventh lens satisfy: -1.86 ≤ f6 / f7 ≤ -0.

85.

15. The fixed focus lens according to claim 1 or 2, wherein An Abbe number Vd6 of the sixth lens, an Abbe number Vd7 of the seventh lens and a combined focal length f67 of the sixth lens and the seventh lens satisfy: 1≤(Vd6-Vd7) / |f67|≤7.

16. The fixed focus lens according to claim 1 or 2, characterized in that, An effective focal length f8 of the eighth lens and a total effective focal length f of the fixed focus lens satisfy: 2.6≤f8 / f≤6.

05.

17. The fixed focus lens of claim 1 or 2, wherein, An effective focal length f8 of the eighth lens and a radius of curvature R82 of an image side surface of the eighth lens satisfy: |f8 / R82|≤1.

18. The fixed focus lens of claim 1 or 2, wherein, An effective focal length fb of the second lens group and a total effective focal length f of the fixed focus lens satisfy: 2.7≤fb / f≤3.

6.

19. The fixed focus lens of claim 1 or 2, wherein, An effective focal length fa of the first lens group and an effective focal length fb of the second lens group satisfy: 0.8≤|fa / fb|≤1.

8.

20. The fixed focal length lens of claim 1 or 2, wherein, The maximum field of view FOV of the fixed-focus lens, the image height H corresponding to the maximum field of view of the fixed-focus lens, and the maximum light aperture D of the fixed-focus lens satisfy: 1.65° / mm 2 ≤ FOV / H / D ≤ 2.2° / mm 2 .

21. The fixed focus lens of claim 1 or 2, wherein, A maximum field angle of the fixed focus lens corresponding to an image height H and a maximum light aperture D of the fixed focus lens satisfy: 4.8≤D / H≤5.

5.

22. The fixed focus lens of claim 1 or 2, wherein, An optical total length TTL of the fixed focus lens and a maximum light aperture D of the fixed focus lens satisfy: 0.9≤TTL / D≤1.

23. The fixed focus lens of claim 1 or 2, wherein, A back focal length BFL of the fixed focus lens and a total effective focal length f of the fixed focus lens satisfy: 1.23≤BFL / f≤1.

59.

24. The fixed focus lens of claim 1 or 2, wherein, The total effective focal length f of the fixed-focus lens, the effective focal length f1 of the first lens, the effective focal length f4 of the fourth lens, and the combined focal length f67 of the sixth lens and the seventh lens satisfy: -5.9mm 2 ≤f x f1 x f4 / |f67|≤-1.4mm 2 .

25. The fixed focus lens of claim 1 or 2, wherein, The fixed focus lens satisfies at least one of the following conditional expressions: 2.5 < |fa / f| < 5.25; 6.85 < f9 / f1 < 18.4; -4.9 < f1 / f < -3.45; -1.8 < f12 / f < -1.25; -2.8 < f2 / R22 < -2.05; 1.1 < f3 / fa < 3.85; 0.65 < |f4 / fa| < 1.8; 0.05 < |(R42+R51) / (R42-R51)| < 0.6; 0.4 < f4 / f5 < 1.3; 2 < |f67| / fb < 7.9; -1.7 < f6 / f7 < -0.85; 1.1 < (Vd6-Vd7) / |f67| < 6.95; 2.6 < f8 / f < 3.8; 2.74 < f8 / f < 3.8; 0.35 < |f8 / R82| < 0.85; 2.7 < fb / f < 3.25; 0.8 < |fa / fb| < 1.65; 1.7° / mm 2 ≤ FOV / H / D ≤ 1.9° / mm 2 ; 4.9 < D / H < 5.45; 1.25 < BFL / f < 1.45; -5.35 mm 2 ≤ f x f1 x f4 / |f67| ≤ -1.75 mm 2 ; wherein fa is an effective focal length of the first lens group, f is a total effective focal length of the fixed focus lens, f9 is an effective focal length of the ninth lens, f1 is an effective focal length of the first lens, f12 is a combined focal length of the first lens and the second lens, f2 is an effective focal length of the second lens, R22 is a radius of curvature of an image side surface of the second lens, f3 is an effective focal length of the third lens, f4 is an effective focal length of the fourth lens, R42 is a radius of curvature of an image side surface of the fourth lens, R51 is a radius of curvature of an object side surface of the fifth lens, f67 is a combined focal length of the sixth lens and the seventh lens, fb is an effective focal length of the second lens group, f6 is an effective focal length of the sixth lens, f7 is an effective focal length of the seventh lens, Vd6 is an Abbe number of the sixth lens, Vd7 is an Abbe number of the seventh lens, f8 is an effective focal length of the eighth lens, R82 is a radius of curvature of an image side surface of the eighth lens, FOV is a maximum field angle of the fixed focus lens, H is an image height corresponding to the maximum field angle of the fixed focus lens, D is a maximum light aperture of the fixed focus lens, and BFL is a back focal length of the fixed focus lens.

Images