Prime lens

Abstract

The utility model discloses a prime lens. The prime lens sequentially comprises a first lens group and a second lens group from an object side to an image side along an optical axis, the first lens group sequentially comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with negative focal power and a fourth lens with positive focal power from the object side to the image side; the second lens group sequentially comprises a fifth lens with positive focal power, a sixth lens with positive focal power, a seventh lens with negative focal power and an eighth lens with positive focal power from the object side to the image side; wherein the object side surfaces of the first lens and the second lens are convex surfaces, and the image side surfaces are concave surfaces; the prime lens satisfies the following conditions: 2.5 < = fa / f < = 6 and-5.9 < = f * f1 * f4 / f67 < =-1.4, fa is the effective focal length of the first lens group, f is the total effective focal length of the prime lens, f1 is the effective focal length of the first lens, f4 is the effective focal length of the fourth lens, and f67 is the combined focal length of the sixth lens and the seventh lens.

Description

Technical Field

[0001] The present application relates to the field of optical devices, and in particular to a fixed-focus lens. Background Art

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

[0003] However, existing optical imaging lenses often have some problems. For example, the field of view of the optical imaging lens is small; or the aperture of the optical imaging lens is small, which cannot meet the requirements of large aperture; or the optical imaging lens cannot meet the requirements of high brightness while achieving high resolution. Utility Model Content

[0004] The present application provides a fixed-focus lens that can at least solve or partially solve at least one problem or other problems existing in the prior art.

[0005] On the one hand, the present application provides a fixed-focus lens, which includes, in order from the object side to the image side along the optical axis, a first lens group and a second lens group; wherein the first lens group includes, in order 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 includes, in order 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 fixed-focus lens satisfies the following conditions: 2.5≤|fa / f|≤6 and -5.9≤f×f1×f4 / |f67|≤-1.4, wherein fa is the effective focal length of the first lens group, f is the total effective focal length of the fixed-focus lens, f1 is the effective focal length of the first lens, f4 is the effective focal length of the fourth lens, and f67 is the combined focal length of the sixth lens and the seventh lens.

[0006] According to an exemplary embodiment of the present application, the fixed-focus lens further includes a ninth lens having negative optical power, and the ninth lens is located on the object side of the first lens.

[0007] According to an exemplary embodiment of the present application, 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 and image-side surface of the sixth lens are 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 the present application, the sixth lens and the seventh lens are cemented to form a cemented lens.

[0009] According to an exemplary embodiment of the present 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 the present 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 the present 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 the following: -2.2≤f12 / f≤-1.2.

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

[0013] According to an exemplary embodiment of the present 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 the present 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 the present application, a curvature radius R42 of the image-side surface of the fourth lens and a curvature radius R51 of the object-side surface of the fifth lens satisfy: |(R42+R51) / (R42-R51)|≤0.7.

[0016] According to an exemplary embodiment of the present 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 the present application, 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.

[0018] According to an exemplary embodiment of the present 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 the present 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 the present 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≤6.05.

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

[0022] According to an exemplary embodiment of the present 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 the present 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 the present 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 clear aperture D of the fixed-focus lens satisfy the following conditions: 1.65° / mm 2 ≤FOV / H / D≤2.2° / mm 2 .

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

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

[0027] According to an exemplary embodiment of the present 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 the present application, the fixed-focus lens satisfies at least one of the following conditional expressions:

[0029] 2.5≤|fa / f|≤5.7; 6.85≤f9 / f1≤18.4; -4.9≤f1 / f≤-3.45; -1.8≤f12 / f≤-1.25; -2.8≤f2 / R2 2≤-2.05; 1.05≤f3 / fa≤3.85; 0.6≤|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; 2.7≤f8 / f≤3.8; 0.35≤|f8 / R82|≤0.85; 2.7≤fb / f≤3.25; 0.8≤|fa / fb|≤1.75; 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 ;

[0030] Among them, 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 lens and the second lens, f2 is the effective focal length of the second lens, R22 is the radius of curvature of the image side 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 of the fourth lens, R51 is the radius of curvature of the object side of the fifth lens, and f67 is where fb is the combined focal length of the sixth lens and the seventh lens, f6 is the effective focal length of the second lens group, 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-focus lens, H is the image height corresponding to the maximum field of view of the fixed-focus lens, D is the maximum clear aperture of the fixed-focus lens, and BFL is the back focal length of the fixed-focus lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other features, objects and advantages of the present application will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings, in which:

[0032] Figure 1 1 shows a schematic structural diagram of a fixed-focus lens according to Example 1 of the present application;

[0033] Figure 21 shows a schematic structural diagram of a fixed-focus lens according to Example 2 of the present application;

[0034] Figure 3 1 shows a schematic structural diagram of a fixed-focus lens according to Example 3 of the present application;

[0035] Figure 4 1 shows a schematic structural diagram of a fixed-focus lens according to Example 4 of the present application;

[0036] Figure 5 1 shows a schematic structural diagram of a fixed-focus lens according to Example 5 of the present application;

[0037] Figure 6 1 shows a schematic structural diagram of a fixed-focus lens according to Example 6 of the present application;

[0038] Figure 7 1 shows a schematic structural diagram of a fixed-focus lens according to Example 7 of the present application;

[0039] Figure 8 A schematic structural diagram of a fixed-focus lens according to Example 8 of the present application is shown. DETAILED DESCRIPTION

[0040] In order to better understand the present application, various aspects of the present application are described in detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application and are not intended to limit the scope of the present application in any way.

[0041] In the drawings, the thickness, size, and shape of the lenses are slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical and aspherical surfaces shown in the drawings are provided by way of example. That is, the shapes of the spherical and aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0042] In this article, the paraxial region refers to the area near the optical axis. If a lens surface is convex and the location of the convex surface is undefined, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the location of the concave surface is undefined, 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.

[0043] It should also be understood that the terms "comprising," "including," "having," "include," and / or "including," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not preclude 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 solely to distinguish one feature from another and do not imply any limitation of the features. It should be noted that the longitudinal direction described herein is the direction perpendicular to the optical axis.

[0044] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Terms should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0045] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0046] A fixed-focus lens according to an exemplary embodiment of the present 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 in sequence along the optical axis from the object side to the image side.

[0047] In example embodiments, the fixed focus lens may further include a ninth lens, and the ninth lens may be located on the object side of the first lens.

[0048] In an exemplary embodiment, the ninth lens element may have negative optical power. The object-side surface of the ninth lens element may be convex, and the image-side surface may be concave. The ninth lens element is a negative lens element, and its convex-concave configuration facilitates the collection of incident light from the object side, reducing the angle of incidence of the incident light on the object-side surface of the first lens element. This allows the light to smoothly enter the rear optical system, effectively correcting system aberrations. For example, the ninth lens element may be made of glass, which can act as a protective cover, thereby protecting the fixed-focus lens.

[0049] 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 configuring the first lens as a negative lens and adopting a convex-concave configuration, light rays at large angles can enter the rear system smoothly, while reducing the angle of incidence of light rays on the object-side surface of the second lens. This effectively avoids aberrations caused by excessively large angles of incidence in subsequent lenses, thereby improving the resolving power of the fixed-focus lens.

[0050] In an exemplary embodiment, the second lens element may have negative optical power. The object-side surface of the second lens element may be convex, and the image-side surface may be concave. By setting the second lens element to have negative optical power and a convex-concave configuration, the trajectory of light can be controlled, ensuring a smooth transition to the rear optical system. This improves aberration correction in the central field of view and enhances the resolving power of the fixed-focus lens. For example, the second lens element may be an aspheric lens.

[0051] In exemplary embodiments, the third lens and the fourth lens may be cemented to form a cemented lens.

[0052] In an exemplary embodiment, the third lens element may have negative optical power. The object-side surface of the third lens element is concave. By configuring the third lens element with negative optical power and a concave object-side surface, the third lens element can be combined with a fourth lens element having positive optical power, thereby improving the spherical aberration correction and resolving power of the fixed-focus lens element. By way of example, the image-side surface of the third lens element may be flat, concave, or concave.

[0053] In an exemplary embodiment, the fourth lens may have positive optical power. The image side surface of the fourth lens may be a convex surface. The fourth lens may be set as a positive lens, and the image side surface may be set as a convex surface, so that the fourth lens can be matched with the third lens having negative optical power, which is beneficial to correcting the spherical aberration of the fixed-focus lens; at the same time, the fourth lens can also cooperate with the fifth lens behind it to effectively correct the axial chromatic aberration of the fixed-focus lens and achieve a large aperture of the fixed-focus lens. As an example, the aperture value FNO of the fixed-focus lens is FNO≤1.8, and further, FNO=1.3. As an example, the object side surface of the fourth lens may be a plane, a convex surface, or a concave surface. As an example, the fourth lens may be a glass lens.

[0054] 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 setting its object-side surface as a convex surface, 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 is made of a thermal expansion-stable material. It is combined with a spherical lens (such as the fourth lens and the sixth lens) to facilitate thermal compensation of the fixed-focus lens.

[0055] In example embodiments, the sixth lens and the seventh lens may be cemented to form a cemented lens.

[0056] In an exemplary embodiment, the sixth lens element may have positive optical power. The object-side surface and image-side surface of the sixth lens element may be convex. By configuring the sixth lens element as a biconvex positive lens and cementing the sixth lens element with the seventh lens element to form a doublet, this facilitates smooth light transmission, reduces the tolerance sensitivity of the sixth lens element, and improves the production yield of fixed-focus lenses. For example, the sixth lens element may be made of a material with a low refractive index and a high Abbe number to effectively correct vertical axial chromatic aberration in fixed-focus lenses, thereby improving the imaging quality of fixed-focus lenses.

[0057] In an exemplary embodiment, the seventh lens element may have negative optical power. The object-side surface of the seventh lens element may be concave, and the image-side surface may be either convex or concave. By configuring the seventh lens element as a negative lens element with its object side concave, and cementing the seventh lens element with the sixth lens element to form a doublet, this facilitates smooth light transmission, reduces the seventh lens element's tolerance sensitivity, and improves the production yield of fixed-focus lenses. It also effectively corrects vertical chromatic aberration in fixed-focus lenses, enhancing their imaging quality.

[0058] In an exemplary embodiment, the eighth lens element may have positive optical power. The object-side surface of the eighth lens element may be convex, and the image-side surface may be convex or concave. By configuring the eighth lens element as a positive lens element convex toward the object side, the trajectory of light can be effectively controlled, lowering the angle of incidence of light passing through the eighth lens element. This reduces the chief ray angle (CRA) of the fixed-focus lens element, facilitating better matching with the chip, for example, better matching the chip's CRA curve.

[0059] In an exemplary embodiment, the fixed-focus lens may further include an aperture. The aperture may be located between the fourth lens element and the fifth lens element. Providing an aperture helps converge light, reduces the rear port diameter of the fixed-focus lens, reduces the assembly stability of the fixed-focus lens, and improves the imaging quality of the fixed-focus lens.

[0060] In an exemplary embodiment, the fixed focus lens may further include a filter for correcting color deviation.

[0061] In an exemplary embodiment, the image height H corresponding to the maximum field angle of the fixed-focus lens may be 4.5 mm to 4.7 mm. Further, H may be 4.6 mm.

[0062] In an exemplary embodiment, at least one of the second, third, fourth, fifth, and eighth lenses has an aspherical surface on its object-side and / or image-side surfaces. Aspherical surfaces have a superior curvature radius, improving distortion and aberrations. Using an aspherical surface minimizes aberrations that occur during imaging, thereby improving the resolving power of a fixed-focus lens.

[0063] In an exemplary embodiment, any one of the first to eighth lenses may be a glass lens or a plastic lens. A glass lens can effectively suppress the deviation of the back focal length of a fixed-focus lens caused by temperature changes, thereby improving the stability of the fixed-focus lens. At the same time, a glass lens can effectively avoid the problem of image blur caused by high or low temperature environments, ensuring the normal use of the fixed-focus lens, and better correcting system chromatic aberration to improve the resolution capability of the fixed-focus lens. A plastic lens can effectively reduce the cost of the fixed-focus lens. As an example, any one of the first to eighth lenses is a glass lens, which is conducive to improving the imaging quality and reliability of the fixed-focus lens. For example, when the first to eighth lenses are all glass lenses, the fixed-focus lens has a wider operating temperature range and can maintain stable optical performance within the range of -40°C to 85°C. As an example, some of the lenses from the first to eighth lenses are glass lenses, and the remaining lenses are plastic lenses. The fixed-focus lens adopts a glass-plastic hybrid form, which can effectively reduce the cost of the fixed-focus lens.

[0064] 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 following relationship: 2.5 ≤ |fa / f| ≤ 6. In one example, 2.5 ≤ |fa / f| ≤ 5.7. 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 can bring the image-side principal plane of the fixed-focus lens as a whole closer to the imaging plane, facilitating the reverse telephoto effect of the fixed-focus lens and increasing the back focal length of the fixed-focus lens, which facilitates 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 generated by reflections from the center of the lens and color filter, thereby improving the imaging quality of the fixed-focus lens.

[0065] In an exemplary embodiment, the effective focal length f9 of the ninth lens element and the effective focal length f1 of the first lens element may satisfy the following relationship: 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 element to the effective focal length of the first lens element facilitates the entry of incident light at wide angles into the fixed-focus lens, thereby expanding the fixed-focus lens's field of view (FOV), for example, to ≥ 196°. This also effectively prevents the generation of aberrations.

[0066] 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 the following relationship: -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 wide-angle light to enter the rear system smoothly, reducing the incident angle of light on the object side of the second lens. This effectively prevents higher-order aberrations in subsequent lenses caused by excessively large incident angles, thereby improving the resolution performance of the fixed-focus lens.

[0067] 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 the following: -2.2 ≤ f12 / f ≤ -1.2. In one example, -1.8 ≤ f12 / f ≤ -1.25. Properly 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 effectively controls the trajectory of light. Furthermore, the first and second lenses collectively diverge the light, facilitating the maximum possible penetration of wide-angle light into the rear optical system and improving the relative illumination of the fixed-focus lens.

[0068] 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 the following relationship: -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 helps control the trajectory of light, ensuring smooth incident light on the object-side surface of the third lens. This helps reduce the tolerance sensitivity of the fixed-focus lens, while also facilitating correction of aberrations in the central field of view, thereby improving the resolving power of the fixed-focus lens.

[0069] In an exemplary embodiment, the effective focal length f3 of the third lens and the effective focal length fa of the first lens group may satisfy the following relationship: 1 ≤ f3 / fa ≤ 4. In one example, 1.05 ≤ 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 facilitates correcting spherical aberration and improving the resolving power of a fixed-focus lens.

[0070] In an exemplary embodiment, the effective focal length f4 of the fourth lens and the effective focal length fa of the first lens group may satisfy the following relationship: 0.52 ≤ |f4 / fa| ≤ 1.87. In one example, 0.6 ≤ |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 facilitates correction of spherical aberration and axial chromatic aberration in a fixed-focus lens, thereby improving the resolving power of the fixed-focus lens.

[0071] 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 the following relationship: |(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 facilitates controlling the shape of the two lenses on either side of the aperture, controlling the direction of light, achieving a smooth transition of light, effectively reducing the tolerance sensitivity of fixed-focus lenses, and improving the production yield of fixed-focus lenses.

[0072] 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 the following relationship: 0.4 ≤ f4 / f5 ≤ 1.5. In one example, 0.4 ≤ f4 / f5 ≤ 1.3. Properly allocating the effective focal lengths of the fourth lens and the fifth lens can effectively correct spherical aberration and axial chromatic aberration of the fixed-focus lens, improving its resolution. It also facilitates achieving a large aperture for the fixed-focus lens. Furthermore, it facilitates eliminating temperature drift, enabling thermal compensation for the fixed-focus lens and ensuring good temperature performance. As an example, the aperture value FNO of the fixed-focus lens is ≤ 1.8, and further, FNO = 1.3.

[0073] 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 may satisfy the following: 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 facilitates smooth light transmission, reduces the tolerance sensitivity of the sixth and seventh lenses, and improves the production yield of fixed-focus lenses.

[0074] In an exemplary embodiment, the effective focal length f6 of the sixth lens element and the effective focal length f7 of the seventh lens element can satisfy the following relationship: -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 element to the effective focal length of the seventh lens element allows the two positive and negative lenses to be used together, balancing the astigmatism generated by the rear lens group (e.g., the second lens group) and improving the resolution of the fixed-focus lens.

[0075] In an exemplary embodiment, the Abbe number Vd6 of the sixth lens element, the Abbe number Vd7 of the seventh lens element, and the combined focal length f67 of the sixth and seventh lenses may satisfy the following: 1 ≤ (Vd6 - Vd7) / |f67| ≤ 7. In one example, 1.1 ≤ (Vd6 - Vd7) / |f67| ≤ 6.95. By properly selecting the lens materials for 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, vertical chromatic aberration of a fixed-focus lens can be effectively corrected, purple fringing can be effectively avoided, and the imaging quality of the fixed-focus lens can be improved.

[0076] 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 the following relationship: 2.6 ≤ f8 / f ≤ 6.05. In one example, 2.6 ≤ f8 / f ≤ 3.8, and further, 2.7 ≤ f8 / f ≤ 3.8. Properly configuring the ratio of the effective focal length of the eighth lens to the total effective focal length of the fixed-focus lens effectively controls light distribution and ensures that the deflection angle of the maximum field of view light emitted from the eighth lens is within an appropriate range, thereby ensuring that the fixed-focus lens better matches the chip requirements.

[0077] 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 may satisfy the following relationship: |f8 / R82|≤1. In one example, 0.35≤|f8 / R82|≤0.85. Properly configuring the ratio of the effective focal length of the eighth lens 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, thereby better matching the chip and its CRA curve requirements, and improving the tolerance and manufacturability of the fixed-focus lens.

[0078] 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 may satisfy the following: 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 facilitates achieving a large aperture for the fixed-focus lens. For example, the aperture value FNO of the fixed-focus lens may be ≤ 1.8, and further, FNO = 1.3.

[0079] 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 may satisfy the following: 0.8 ≤ |fa / fb| ≤ 1.8. In one example, 0.8 ≤ |fa / fb| ≤ 1.75. Properly configuring the ratio of the effective focal length of the first lens group to the effective focal length of the second lens group facilitates controlling the overall light distribution of the fixed-focus lens, achieving smooth light transitions, reducing sensitivity, and improving imaging quality.

[0080] 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 clear aperture D of the fixed-focus lens can satisfy the following conditions: 1.65° / mm 2 ≤FOV / H / D≤2.2° / mm 2 In one example, 1.7° / mm 2 ≤FOV / H / D≤1.9° / mm 2. Reasonable configuration of the relationship between the maximum field of view of the fixed-focus lens, the image height corresponding to the maximum field of view of the fixed-focus lens, and the maximum clear aperture of the fixed-focus lens can effectively control the viewpoint position of the fixed-focus lens and ensure that the maximum clear aperture of the fixed-focus lens meets the design requirements; at the same time, when the image height is fixed, the smaller the focal length of the fixed-focus lens, the larger the maximum field of view of the fixed-focus lens, and vice versa. By controlling FOV / H / D, it can be ensured that the fixed-focus lens has a reasonable maximum field of view when corresponding to different sensors. It should be noted that the maximum clear aperture of the fixed-focus lens can be the effective clear aperture corresponding to the object side of the first lens at the maximum field of view angle.

[0081] In an exemplary embodiment, the image height H corresponding to the maximum field of view angle of the fixed-focus lens and the maximum clear aperture D of the fixed-focus lens can satisfy the following: 4.8 ≤ D / H ≤ 5.5. In one example, 4.9 ≤ D / H ≤ 5.45. Properly configuring the ratio of the image height corresponding to the maximum field of view angle of the fixed-focus lens to the maximum clear aperture of the fixed-focus lens can help reduce the front aperture of the fixed-focus lens, thereby achieving vertical miniaturization of the fixed-focus lens. It should be noted that the maximum clear aperture of the fixed-focus lens can be the effective clear aperture corresponding to the object-side surface of the first lens at the maximum field of view angle.

[0082] In an exemplary embodiment, the total optical length (TTL) of the fixed-focus lens and its maximum optical aperture (D) may satisfy the following relationship: 0.9 ≤ TTL / D ≤ 1. Properly configuring the ratio of the total optical length of the fixed-focus lens to its maximum optical aperture facilitates compact design and miniaturization of the fixed-focus lens. It should be noted that the maximum optical aperture of the fixed-focus lens may be the effective optical aperture corresponding to the object-side surface of the first lens at the maximum field of view angle.

[0083] 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 may satisfy the following: 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 of the fixed-focus lens to the total effective focal length of the fixed-focus lens while miniaturizing the fixed-focus lens, the back focal length of the fixed-focus lens can be increased, thereby reserving space for the installation of other optical components, facilitating the assembly of the fixed-focus lens, avoiding interference between optical components, and improving the assembly yield of the fixed-focus lens.

[0084] 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 lens and the seventh lens may satisfy: -5.9≤f×f1×f4 / |f67|≤-1.4. In one example, -5.35 mm 2 ≤f×f1×f4 / |f67|≤-1.75mm 2The first, fourth, sixth, and seventh lenses are made of glass lenses, 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 can effectively correct chromatic aberration produced by the fixed-focus lens, improve the resolution of the fixed-focus lens, and suppress imaging shift caused by temperature changes in the fixed-focus lens, thereby improving the stability and quality of the fixed-focus lens.

[0085] The fixed-focus lens according to the above-described embodiment of the present application can utilize multiple lenses. By rationally allocating the optical power, surface shape, and optical parameters of each lens, it is possible to achieve at least one of the following: a large field of view, a large aperture, high resolution, high illumination, and low cost for the optical system. The fixed-focus lens provided in this application has a large field of view, for example, FOV ≥ 196°, which can capture a wider range of targets, and has high resolution, for example, a fixed-focus lens with 25 million pixels.

[0086] However, those skilled in the art will appreciate that, without departing from the technical solution claimed in the present application, the number of lenses constituting the fixed-focus lens may be changed to obtain the various results and advantages described in this specification.

[0087] Specific embodiments of fixed-focus lenses applicable to the above-mentioned embodiments will be further described below with reference to the accompanying drawings.

[0088] Example 1

[0089] The following reference Figure 1 A fixed-focus lens according to Example 1 of the present application will be described. Figure 1 Schematic diagram of the structure of a fixed-focus lens according to Example 1 of the present application.

[0090] like Figure 1 As shown, the fixed-focus lens includes, in order from the object side to the image side along the optical axis, a first lens group and a second lens group. 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 disposed 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 doublet.

[0091] The ninth lens L9 has negative refractive power, its object-side surface S1 is convex, and its image-side surface S2 is concave.

[0092] The first lens L1 has negative refractive power, an object-side surface S3 thereof is convex, and an image-side surface S4 thereof is concave.

[0093] The second lens L2 has negative refractive power, its object-side surface S5 is convex, and its image-side surface S6 is concave.

[0094] The third lens L3 has negative refractive power, and its object-side surface S7 and image-side surface S8 are concave.

[0095] The fourth lens L4 has positive refractive power, and its object-side surface S9 and image-side surface S10 are convex.

[0096] The fifth lens L5 has positive refractive power, and its object-side surface S12 and image-side surface S13 are convex.

[0097] The sixth lens L6 has positive refractive power, and its object-side surface S14 is convex and its image-side surface is convex.

[0098] The seventh lens L7 has negative refractive power, and its object-side surface S15 and image-side surface S16 are concave.

[0099] The eighth lens L8 has positive refractive power, and its object-side surface S17 and image-side surface S18 are convex.

[0100] A filter CG may also be provided between the eighth lens L8 and the imaging surface IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object sequentially passes through the surfaces S1-S10 and S12-S18 and is finally imaged on the imaging surface IMA. It should be noted that the surfaces S1-S10 and S12-S20 are Figure 1 Not shown in the figure.

[0101] Table 1 shows basic parameters of the fixed-focus lens of Example 1, wherein the units of curvature radius and thickness / distance are all millimeters (mm).

[0102]

[0103]

[0104] Table 1

[0105] In this embodiment, the total effective focal length F of the fixed-focus lens is 1.42, the aperture Fno of the fixed-focus lens is 1.3, and the relative illumination of the fixed-focus lens is 70%.

[0106] The object-side surface S5 and image-side surface S6 of the second lens element L2, the object-side surface S7 and image-side surface S8 of the third lens element L3, the object-side surface S12 and image-side surface S13 of the fifth lens element L5, and the object-side surface S17 and image-side surface S18 of the eighth lens element L8 are all aspherical surfaces. The surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical surface formula:

[0107]

[0108] Where x is the distance vector from the vertex of the aspheric surface at a height of h along the optical axis; c is the paraxial curvature of the aspheric 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 correction coefficient for the i-th order of the aspheric surface. Table 2 shows the conic coefficient k and the higher-order coefficients A4, A6, A8, A10, A12, A14, and A16 that can be used for the aspheric surfaces S5, S6, S7, S8, S12, S13, S17, and S18 in Example 1.

[0109] 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

[0110] Table 2

[0111] Example 2

[0112] The following reference Figure 2 A fixed-focus lens according to Example 2 of the present application will be described. Figure 2 Schematic diagram of the structure of a fixed-focus lens according to Example 2 of the present application.

[0113] like Figure 2 As shown, the fixed-focus lens includes, in order from the object side to the image side along the optical axis, a first lens group and a second lens group. 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 disposed 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 doublet.

[0114] The ninth lens L9 has negative refractive power, its object-side surface S1 is convex, and its image-side surface S2 is concave.

[0115] The first lens L1 has negative refractive power, an object-side surface S3 thereof is convex, and an image-side surface S4 thereof is concave.

[0116] The second lens L2 has negative refractive power, its object-side surface S5 is convex, and its image-side surface S6 is concave.

[0117] The third lens L3 has negative refractive power, and its object-side surface S7 and image-side surface S8 are concave.

[0118] The fourth lens L4 has positive refractive power, and its object-side surface S9 and image-side surface S10 are convex.

[0119] The fifth lens L5 has positive refractive power, its object-side surface S12 is convex, and its image-side surface S13 is concave.

[0120] The sixth lens L6 has positive refractive power, and its object-side surface S14 is convex and its image-side surface is convex.

[0121] The seventh lens L7 has negative refractive power, and its object-side surface S15 and image-side surface S16 are concave.

[0122] The eighth lens L8 has positive refractive power, and its object-side surface S17 and image-side surface S18 are convex.

[0123] A filter CG may also be provided between the eighth lens L8 and the imaging surface IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object sequentially passes through the surfaces S1-S10 and S12-S18 and is finally imaged on the imaging surface IMA. It should be noted that the surfaces S1-S10 and S12-S20 are Figure 2 Not shown in the figure.

[0124] Table 3 shows the basic parameters of the fixed-focus lens of Example 2, wherein the units of curvature radius and thickness / distance are all millimeters (mm).

[0125]

[0126] Table 3

[0127] In this embodiment, the total effective focal length F of the fixed-focus lens is 1.43, the aperture Fno of the fixed-focus lens is 1.3, and the relative illumination of the fixed-focus lens is 70%.

[0128] 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 shows the conic coefficient k and the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18 of the aspherical surfaces S5, S6, S7, S8, S12, S13, S17, and S18 that can be used in Example 2. 10 、A 12 、A 14 and A 16 .

[0129]

[0130]

[0131] Table 4

[0132] Example 3

[0133] The following reference Figure 3 A fixed-focus lens according to Example 3 of the present application will be described. Figure 3Schematic diagram of the structure of a fixed-focus lens according to Example 3 of the present application.

[0134] like Figure 3 As shown, the fixed-focus lens includes, in order from the object side to the image side along the optical axis, a first lens group and a second lens group. 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 disposed 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 doublet.

[0135] The ninth lens L9 has negative refractive power, its object-side surface S1 is convex, and its image-side surface S2 is concave.

[0136] The first lens L1 has negative refractive power, an object-side surface S3 thereof is convex, and an image-side surface S4 thereof is concave.

[0137] The second lens L2 has negative refractive power, its object-side surface S5 is convex, and its image-side surface S6 is concave.

[0138] The third lens L3 has negative refractive power, and its object-side surface S7 and image-side surface S8 are concave.

[0139] The fourth lens L4 has positive refractive power, and its object-side surface S9 and image-side surface S10 are convex.

[0140] The fifth lens L5 has positive refractive power, its object-side surface S12 is convex, and its image-side surface S13 is concave.

[0141] The sixth lens L6 has positive refractive power, and its object-side surface S14 is convex and its image-side surface is convex.

[0142] The seventh lens L7 has negative refractive power, and its object-side surface S15 and image-side surface S16 are concave.

[0143] The eighth lens L8 has positive refractive power, and its object-side surface S17 and image-side surface S18 are convex.

[0144] A filter CG may also be provided between the eighth lens L8 and the imaging surface IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object sequentially passes through the surfaces S1-S10 and S12-S18 and is finally imaged on the imaging surface IMA. It should be noted that the surfaces S1-S10 and S12-S20 are Figure 3 Not shown in the figure.

[0145] Table 5 shows the basic parameters of the fixed-focus lens of Example 3, wherein the units of curvature radius and thickness / distance are all millimeters (mm).

[0146]

[0147]

[0148] Table 5

[0149] In this embodiment, the total effective focal length F of the fixed-focus lens is 1.44, the aperture Fno of the fixed-focus lens is 1.6, and the relative illumination of the fixed-focus lens is 70%.

[0150] 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 6 shows the conic coefficient k and the high-order coefficients A4, A6, A8, A9, A10 of each aspherical surface S5, S6, S7, S8, S12, S13, S17, and S18 that can be used in Example 3. 10 、A 12 、A 14 and A 16 .

[0151] Face number k A4 A6 A8 A10 A12 A14 A16 S5 2.99 8.66E-03 -2.14E-03 2.58E-04 -3.45E-05 2.72E-06 -8.05E-08 0.00E+00 S6 -0.40 2.13E-02 3.99E-03 -2.89E-03 1.28E-03 -2.22E-04 -1.75E-05 4.25E-06 S7 -1.59 2.42E-02 -3.32E-03 5.86E-04 -2.84E-05 3.18E-05 -1.64E-05 1.42E-06 S8 -11.98 2.01E-02 -4.69E-03 8.42E-04 4.30E-05 -6.70E-05 6.42E-06 4.36E-07 S12 -2.65 9.06E-03 2.43E-03 -6.65E-04 4.42E-04 -1.29E-04 1.93E-05 -8.52E-07 S13 0.00 6.38E-03 6.90E-04 1.83E-03 -8.33E-04 2.73E-04 -4.69E-05 5.09E-06 S17 -4.47 1.04E-02 -2.03E-03 4.70E-04 -8.15E-05 9.41E-06 -4.13E-07 0.00E+00 S18 1.10 8.44E-03 -6.44E-04 3.13E-04 -6.59E-05 7.22E-06 -4.99E-07 4.73E-08

[0152] Table 6

[0153] Example 4

[0154] The following reference Figure 4 A fixed-focus lens according to Example 4 of the present application will be described. Figure 4 Schematic diagram of the structure of a fixed-focus lens according to Example 4 of the present application.

[0155] like Figure 4 As shown, the fixed-focus lens includes, in order from the object side to the image side along the optical axis, a first lens group and a second lens group. 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 disposed 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 doublet.

[0156] The ninth lens L9 has negative refractive power, its object-side surface S1 is convex, and its image-side surface S2 is concave.

[0157] The first lens L1 has negative refractive power, an object-side surface S3 thereof is convex, and an image-side surface S4 thereof is concave.

[0158] The second lens L2 has negative refractive power, its object-side surface S5 is convex, and its image-side surface S6 is concave.

[0159] The third lens L3 has negative refractive power, and its object-side surface S7 and image-side surface S8 are concave.

[0160] The fourth lens L4 has positive refractive power, and its object-side surface S9 and image-side surface S10 are convex.

[0161] The fifth lens L5 has positive refractive power, and its object-side surface S12 and image-side surface S13 are convex.

[0162] The sixth lens L6 has positive refractive power, and its object-side surface S14 is convex and its image-side surface is convex.

[0163] The seventh lens L7 has negative refractive power, and its object-side surface S15 and image-side surface S16 are concave.

[0164] The eighth lens L8 has positive refractive power, and its object-side surface S17 and image-side surface S18 are convex.

[0165] A filter CG may also be provided between the eighth lens L8 and the imaging surface IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object sequentially passes through the surfaces S1-S10 and S12-S18 and is finally imaged on the imaging surface IMA. It should be noted that the surfaces S1-S10 and S12-S20 are Figure 4 Not shown in the figure.

[0166] Table 7 shows the basic parameters of the fixed-focus lens of Example 4, where the units of curvature radius and thickness / distance are all millimeters (mm).

[0167]

[0168] Table 7

[0169] In this embodiment, the total effective focal length F of the fixed-focus lens is set to 1.45, the aperture Fno of the fixed-focus lens is set to 1.8, and the relative illumination of the fixed-focus lens is 74%.

[0170] 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 shows the conic coefficient k and the higher-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18 of the aspherical surfaces S5, S6, S7, S8, S12, S13, S17, and S18 that can be used in Example 4. 10 、A 12 、A 14 and A16 .

[0171]

[0172]

[0173] Table 8

[0174] Example 5

[0175] The following reference Figure 5 A fixed-focus lens according to Example 5 of the present application will be described. Figure 5 Schematic diagram of the structure of a fixed-focus lens according to Example 5 of the present application.

[0176] like Figure 5 As shown, the fixed-focus lens includes, in order from the object side to the image side along the optical axis, a first lens group and a second lens group. 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 disposed 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 doublet.

[0177] The ninth lens L9 has negative refractive power, its object-side surface S1 is convex, and its image-side surface S2 is concave.

[0178] The first lens L1 has negative refractive power, an object-side surface S3 thereof is convex, and an image-side surface S4 thereof is concave.

[0179] The second lens L2 has negative refractive power, its object-side surface S5 is convex, and its image-side surface S6 is concave.

[0180] The third lens L3 has negative refractive power, and its object-side surface S7 and image-side surface S8 are concave.

[0181] The fourth lens L4 has positive refractive power, and its object-side surface S9 and image-side surface S10 are convex.

[0182] The fifth lens L5 has positive refractive power, its object-side surface S12 is convex, and its image-side surface S13 is concave.

[0183] The sixth lens L6 has positive refractive power, and its object-side surface S14 is convex and its image-side surface is convex.

[0184] The seventh lens L7 has negative refractive power, and its object-side surface S15 and image-side surface S16 are concave.

[0185] The eighth lens L8 has positive refractive power, and its object-side surface S17 and image-side surface S18 are convex.

[0186] A filter CG may also be provided between the eighth lens L8 and the imaging surface IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object sequentially passes through the surfaces S1-S10 and S12-S18 and is finally imaged on the imaging surface IMA. It should be noted that the surfaces S1-S10 and S12-S20 are Figure 5 Not shown in the figure.

[0187] Table 9 shows the basic parameters of the fixed-focus lens of Example 5, where the units of curvature radius and thickness / distance are all millimeters (mm).

[0188]

[0189]

[0190] Table 9

[0191] In this embodiment, the total effective focal length F of the fixed-focus lens is 1.44, the aperture Fno of the fixed-focus lens is 1.8, and the relative illumination of the fixed-focus lens is 70%.

[0192] 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.

[0193] Table 10 shows the conic coefficient k and the high-order coefficients A4, A6, A8, A 10 、A 12 、A 14 and A 16 .

[0194] 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

[0195] Table 10

[0196] Example 6

[0197] The following reference Figure 6 A fixed-focus lens according to Example 6 of the present application will be described. Figure 6 Schematic diagram of the structure of a fixed-focus lens according to Example 6 of the present application.

[0198] like Figure 6As shown, the fixed-focus lens includes, in order from the object side to the image side along the optical axis, a first lens group and a second lens group. 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 disposed 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 doublet.

[0199] The ninth lens L9 has negative refractive power, its object-side surface S1 is convex, and its image-side surface S2 is concave.

[0200] The first lens L1 has negative refractive power, an object-side surface S3 thereof is convex, and an image-side surface S4 thereof is concave.

[0201] The second lens L2 has negative refractive power, its object-side surface S5 is convex, and its image-side surface S6 is concave.

[0202] The third lens L3 has negative refractive power, and its object-side surface S7 and image-side surface S8 are concave.

[0203] The fourth lens L4 has positive refractive power, and its object-side surface S9 and image-side surface S10 are convex.

[0204] The fifth lens L5 has positive refractive power, and its object-side surface S12 and image-side surface S13 are convex.

[0205] The sixth lens L6 has positive refractive power, and its object-side surface S14 is convex and its image-side surface is convex.

[0206] The seventh lens L7 has negative refractive power, and its object-side surface S15 and image-side surface S16 are concave.

[0207] The eighth lens L8 has positive refractive power, and its object-side surface S17 and image-side surface S18 are convex.

[0208] A filter CG may also be provided between the eighth lens L8 and the imaging surface IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object sequentially passes through the surfaces S1-S10 and S12-S18 and is finally imaged on the imaging surface IMA. It should be noted that the surfaces S1-S10 and S12-S20 are Figure 6 Not shown in the figure.

[0209] Table 11 shows the basic parameters of the fixed-focus lens of Example 6, where the units of curvature radius and thickness / distance are all millimeters (mm).

[0210]

[0211] Table 11

[0212] In this embodiment, the total effective focal length F of the fixed-focus lens is 1.6, the aperture Fno of the fixed-focus lens is 1.8, and the relative illumination of the fixed-focus lens is 70%.

[0213] 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 shows the conic coefficient k and the higher-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A17, and A18 of the aspherical surfaces 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 .

[0214]

[0215]

[0216] Table 12

[0217] Example 7

[0218] The following reference Figure 7 A fixed-focus lens according to Example 7 of the present application will be described. Figure 7 Schematic diagram of the structure of a fixed-focus lens according to Example 7 of the present application.

[0219] 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 disposed 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 doublet. The sixth lens L6 and the seventh lens L7 are cemented together to form a cemented lens, such as a second doublet.

[0220] The ninth lens L9 has negative refractive power, its object-side surface S1 is convex, and its image-side surface S2 is concave.

[0221] The first lens L1 has negative refractive power, an object-side surface S3 thereof is convex, and an image-side surface S4 thereof is concave.

[0222] The second lens L2 has negative refractive power, its object-side surface S5 is convex, and its image-side surface S6 is concave.

[0223] The third lens L3 has negative refractive power, its object-side surface S7 is concave, and its image-side surface is flat.

[0224] The fourth lens L4 has positive refractive power, its object-side surface S8 is flat, and its image-side surface S9 is convex.

[0225] The fifth lens L5 has positive refractive power, and its object-side surface S11 is convex, and its image-side surface S12 is convex.

[0226] The sixth lens L6 has positive refractive power, and its object-side surface S13 is convex and its image-side surface is convex.

[0227] The seventh lens L7 has negative refractive power, and its object-side surface S14 and image-side surface S15 are concave.

[0228] The eighth lens L8 has positive refractive power, and its object-side surface S16 and image-side surface S17 are convex.

[0229] A filter CG may also be provided between the eighth lens L8 and the imaging surface IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object sequentially passes through the surfaces S1-S10 and S12-S18 and is finally imaged on the imaging surface IMA. It should be noted that the surfaces S1-S10 and S12-S20 are Figure 7 Not shown in the figure.

[0230] Table 13 shows the basic parameters of the fixed-focus lens of Example 7, where the units of curvature radius and thickness / distance are all millimeters (mm).

[0231]

[0232]

[0233] Table 13

[0234] In this embodiment, the total effective focal length F of the fixed-focus lens is 1.52, the aperture Fno of the fixed-focus lens is 1.8, and the relative illumination of the fixed-focus lens is 71%.

[0235] 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 S16 and image-side surface S17 of the eighth lens L8 are all aspherical surfaces. Table 14 shows the conic coefficient k and the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17 of the aspherical surfaces S5, S6, S11, S12, S16, and S17 that can be used in Example 7. 10 、A 12 、A14 and A 16 .

[0236] 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

[0237] Table 14

[0238] Example 8

[0239] The following reference Figure 8 A fixed-focus lens according to Example 8 of the present application will be described. Figure 8 Schematic diagram of the structure of a fixed-focus lens according to Example 8 of the present application.

[0240] like Figure 8 As shown, the fixed-focus lens includes, in order from the object side to the image side along the optical axis, a first lens group and a second lens group. 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 disposed 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 doublet.

[0241] The ninth lens L9 has negative refractive power, its object-side surface S1 is convex, and its image-side surface S2 is concave.

[0242] The first lens L1 has negative refractive power, an object-side surface S3 thereof is convex, and an image-side surface S4 thereof is concave.

[0243] The second lens L2 has negative refractive power, its object-side surface S5 is convex, and its image-side surface S6 is concave.

[0244] The third lens L3 has negative refractive power, and its object-side surface S7 and image-side surface S8 are concave.

[0245] The fourth lens L4 has positive refractive power, and its object-side surface S9 and image-side surface S10 are convex.

[0246] The fifth lens L5 has positive refractive power, its object-side surface S12 is convex, and its image-side surface S13 is concave.

[0247] The sixth lens L6 has positive refractive power, and its object-side surface S14 is convex and its image-side surface is convex.

[0248] The seventh lens L7 has negative refractive power, its object-side surface S15 is concave, and its image-side surface S16 is convex.

[0249] The eighth lens L8 has positive refractive power, its object-side surface S17 is convex, and its image-side surface S18 is concave.

[0250] A filter CG may also be provided between the eighth lens L8 and the imaging surface IMA. The filter CG has an object-side surface S19 and an image-side surface S20. Light from the object sequentially passes through the surfaces S1-S10 and S12-S18 and is finally imaged on the imaging surface IMA. It should be noted that the surfaces S1-S10 and S12-S20 are Figure 8 Not shown in the figure.

[0251] Table 15 shows the basic parameters of the fixed-focus lens of Example 8, where the units of curvature radius and thickness / distance are all millimeters (mm).

[0252]

[0253] Table 15

[0254] In this embodiment, the total effective focal length F of the fixed-focus lens is set to 1.465, the aperture Fno of the fixed-focus lens is set to 1.8, and the relative illumination of the fixed-focus lens is 70%.

[0255] 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 16 shows the conic coefficient k and the higher-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18 of the aspherical surfaces S5, S6, S7, S8, S12, S13, S17, and S18 that can be used in Example 8. 10 、A 12 、A 14 and A 16 .

[0256]

[0257]

[0258] Table 16

[0259] In summary, the conditional expressions in Examples 1 to 8 satisfy the relationship shown in Table 17.

[0260] Conditional formula / Example 1 2 3 4 5 6 7 8 f9 / f1 17.04 17.16 17.91 18.38 18.31 6.87 10.15 17.08 f1 / f -4.81 -4.74 -4.51 -4.37 -4.42 -4.89 -3.48 -4.65 f12 / f -1.69 -1.67 -1.52 -1.55 -1.54 -1.65 -1.26 -1.77 f2 / R22 -2.60 -2.61 -2.45 -2.51 -2.48 -2.20 -2.09 -2.79 f3 / fa 1.91 1.81 1.07 1.25 1.15 1.82 3.81 1.14 |f4 / fa| 1.75 1.49 0.65 0.84 0.72 1.67 1.07 0.95 |(R42+R51) / (R42-R51)| 0.55 0.53 0.24 0.15 0.28 0.38 0.07 0.32 f4 / f5 1.02 0.91 0.55 0.64 0.59 1.26 1.28 0.44 |f67| / fb 6.18 7.89 5.21 5.11 5.21 3.64 2.05 2.46 (Vd6-Vd7) / |f67| 1.45 1.12 1.84 1.91 1.84 4.23 6.90 4.42 f6 / f7 -1.36 -1.33 -1.43 -1.47 -1.42 -1.54 -1.68 -0.86 f8 / f 2.89 2.86 2.74 2.86 2.83 3.24 3.76 6.02 |f8 / R82| 0.76 0.75 0.81 0.79 0.75 0.39 0.36 0.82 |fa / f| 2.55 2.99 5.66 4.39 5.08 2.53 4.06 3.75 fb / f 3.01 3.04 3.15 3.08 3.15 2.80 3.23 2.73 |fa / fb| 0.83 0.96 1.74 1.39 1.57 0.82 1.14 1.37 f×f1×f4 / |f67| -2.32 -1.79 -2.09 -2.15 -2.05 -5.20 -5.28 -5.31 FOV / H / D 1.72 1.71 1.74 1.74 1.75 1.88 1.89 1.73 D / H 5.42 5.43 5.35 5.32 5.33 4.94 4.93 5.38 TTL / D 0.92 0.92 0.92 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

[0261] Table 17

[0262] The present application also provides an imaging device, whose electronic photosensitive element may be a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) element, and the imaging device is equipped with the fixed-focus lens described above.

[0263] The above description is merely a preferred embodiment of the present application and an illustration 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 the technical solutions formed by the specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the inventive concept. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. Fixed focus lens, characterized by: The lens comprises a first lens group and a second lens group in order from the object side to the image side along the optical axis; The first lens group includes, from the object side to the image side, the following lens groups: a first lens having negative optical power, wherein the object-side surface is convex and the image-side surface is concave; a second lens having negative optical power, the object-side surface of which is convex and the image-side surface of which is concave; a third lens having negative optical power; a fourth lens element having positive optical 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 optical power; a seventh lens element having negative optical power; an eighth lens having positive optical power; The fixed focus lens satisfies: 2.5≤|fa / f|≤6 and -5.9mm 2 ≤f×f1×f4 / |f67|≤-1.4mm 2 , Wherein, fa is the effective focal length of the first lens group, f is the total effective focal length of the fixed-focus lens, f1 is the effective focal length of the first lens, f4 is the effective focal length of the fourth lens, and f67 is the combined focal length of the sixth lens and the seventh lens.

2. The fixed-focus lens according to claim 1, wherein: The fixed-focus lens further includes: A ninth lens having negative optical power, wherein the ninth lens is located on the object side of the first lens.

3. The fixed-focus lens according to claim 1, wherein: The sixth lens and the seventh lens are cemented together to form a cemented lens.

4. The fixed-focus lens according to claim 2, wherein: The effective focal length f9 of the ninth lens and the effective focal length f1 of the first lens satisfy the following conditions: 6.5≤f9 / f1≤19.7 or 6.85≤f9 / f1≤18.

4.

5. The fixed-focus lens according to any one of claims 1 to 3, wherein: 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 the following: -2.2≤f12 / f≤-1.

2.

6. The fixed-focus lens according to any one of claims 1 to 3, wherein: The effective focal length f4 of the fourth lens and the effective focal length fa of the first lens group satisfy the following: 0.52≤|f4 / fa|≤1.

87.

7. The fixed-focus lens according to any one of claims 1 to 3, wherein: The effective focal length f4 of the fourth lens and the effective focal length f5 of the fifth lens satisfy the following: 0.4≤f4 / f5≤1.

5.

8. The fixed-focus lens according to any one of claims 1 to 3, wherein: The effective focal length f6 of the sixth lens and the effective focal length f7 of the seventh lens satisfy the following: -1.86≤f6 / f7≤-0.

85.

9. The fixed-focus lens according to any one of claims 1 to 3, 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 aperture D of the fixed-focus lens meet the following requirements: 1.65° / mm 2 ≤FOV / H / D≤2.2° / mm 2 .

10. The fixed-focus lens according to any one of claims 1 to 3, wherein: The fixed-focus lens satisfies at least one of the following conditional expressions: 2.5≤|fa / f|≤5.7;-5≤f1 / f≤-3;-1.8≤f12 / f≤-1.25;-3.3≤f2 / R22≤-1.96;1≤f3 / fa≤4;0.6≤|f4 / fa|≤1.8;|(R42+R51) / (R42-R51)|≤0.7;0.4≤f4 / f5≤1.3;2≤|f67| / fb≤8;-1.7≤f6 / f7≤-0.85;1≤(Vd6-Vd7) / |f67|≤7;2.6≤f8 / f≤6.05;|f8 / R82|≤1;2.7≤fb / f≤3.6;0.8≤|fa / fb|≤1.8;1.7° / mm 2 ≤FOV / H / D≤1.9° / mm 2 ;4.8≤D / H≤5.5;1.23≤BFL / f≤1.59;-5.35mm 2 ≤f×f1×f4 / |f67|≤-1.75mm 2 ; 0.9≤TTL / D≤1; Wherein, fa is the effective focal length of the first lens group, f is the total effective focal length of the fixed focus lens, f1 is the effective focal length of the first lens, f12 is the combined focal length of the first lens and the second lens, 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 lens and the seventh lens. where fb is the effective focal length of the second lens group, f6 is the effective focal length of the sixth lens group, f7 is the effective focal length of the seventh lens group, Vd6 is the Abbe number of the sixth lens group, Vd7 is the Abbe number of the seventh lens group, f8 is the effective focal length of the eighth lens group, R82 is the radius of curvature of the image side surface of the eighth lens group, FOV is the maximum field of view of the fixed-focus lens group, H is the image height corresponding to the maximum field of view of the fixed-focus lens group, D is the maximum clear aperture of the fixed-focus lens group, BFL is the back focal length of the fixed-focus lens group, and TTL is the total optical length of the fixed-focus lens group.

11. The fixed-focus lens according to any one of claims 1 to 3, wherein: The fixed-focus lens satisfies at least one of the following conditional expressions: -4.9≤f1 / f≤-3.45; -2.8≤f2 / R22≤-2.05; 1.05≤f3 / fa≤3.85; 0.05≤|(R42+R51) / (R42-R51)|≤0.6; 2≤|f67| / fb≤7.9; 1.1≤(Vd6-V d7) / |f67|≤6.95; 2.6≤f8 / f≤3.8; 0.35≤|f8 / R82|≤0.85; 2.7≤fb / f≤3.25; 0.8≤|fa / fb|≤1.75; 4.9≤D / H≤5.45; 1.25≤BFL / f≤1.45; Wherein, f1 is the effective focal length of the first lens, f is the total effective focal length of the fixed-focus lens, 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, fa is the effective focal length of the first lens group, 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, f67 is the combined focal length of the sixth lens and the seventh lens, fb is the effective focal length of the second lens group, 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 surface of the eighth lens, D is the maximum clear aperture of the fixed-focus lens, H is the image height corresponding to the maximum field of view of the fixed-focus lens, and BFL is the back focal length of the fixed-focus lens.

Images