Prime lens

Abstract

The utility model discloses a prime lens, which sequentially comprises a first lens with negative diopter, a second lens with negative diopter, a third lens with negative diopter, a fourth lens with negative diopter, a fifth lens with negative diopter and a sixth lens with negative diopter from an object side to an image side, the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a convex surface; the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface; the fourth lens has diopter; a fifth lens having a diopter; the object side surface of the sixth lens is a convex surface, and the image side surface of the sixth lens is a concave surface; the object side surface of the seventh lens is a convex surface, and the image side surface of the seventh lens is a convex surface; an eighth lens having a diopter; a ninth lens having a diopter; the positive and negative attributes of the symbols of the diopters of the fourth lens and the fifth lens are opposite; positive and negative attributes of symbols of diopters of the eighth lens and the ninth lens are opposite; the combined focal length F67 of the sixth lens and the seventh lens and the total effective focal length F of the prime lens meet the condition that F67 / F is larger than or equal to 2.62 and smaller than or equal to 3.53.

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 increasing popularity of security monitoring equipment, higher requirements are placed on monitoring equipment. For example, monitoring equipment needs to have a larger light transmittance and good infrared imaging performance.

[0003] However, there are many deficiencies in the imaging lenses currently on the market. For example, the imaging lenses have a small relative aperture, which leads to poor light transmission performance and low relative illumination at the edge; poor infrared confocality of the imaging lenses and poor infrared imaging effect at night; low resolution and poor imaging quality of the imaging lenses; and too long optical length and large size of the imaging lenses. The above deficiencies will limit the application of imaging lenses in the field of security monitoring. 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] In one aspect of the present application, a fixed-focus lens is provided, which comprises, in order from the object side to the image side along the optical axis: a first lens having negative refractive power, whose object side surface is convex and whose image side surface is concave; a second lens having positive refractive power, whose object side surface is concave and whose image side surface is convex; a third lens having positive refractive power, whose object side surface is convex and whose image side surface is concave; a fourth lens having refractive power, whose object side surface is convex; a fifth lens having refractive power, whose image side surface is convex; a sixth lens having negative refractive power, whose object side surface is convex and whose image side surface is concave; a seventh lens having positive refractive power, whose object side surface is convex and whose image side surface is concave; a lens having an object side surface that is convex and an image side surface that is convex; an eighth lens having a refractive power, whose object side surface and image side surface are concave, or whose object side surface and image side surface are convex; a ninth lens having a refractive power, whose object side surface and image side surface are concave, or whose object side surface and image side surface are convex; wherein, the positive and negative properties of the signs of the refractive powers of the fourth lens and the fifth lens are opposite; the positive and negative properties of the signs of the refractive powers of the eighth lens and the ninth lens are opposite; and a combined focal length F67 of the sixth lens and the seventh lens and a total effective focal length F of the fixed-focus lens satisfy: 2.62≤F67 / F≤3.53.

[0006] According to an exemplary embodiment of the present application, the fourth lens has positive refractive power, and the image-side surface of the fourth lens is a convex surface.

[0007] According to an exemplary embodiment of the present application, the fourth lens has negative refractive power, and the image-side surface of the fourth lens is a concave surface.

[0008] According to an exemplary embodiment of the present application, the fifth lens has negative refractive power, and the object-side surface of the fifth lens is concave.

[0009] According to an exemplary embodiment of the present application, the fifth lens has positive refractive power, and the object-side surface of the fifth lens is a convex surface.

[0010] According to an exemplary embodiment of the present application, the eighth lens has negative refractive power, and both the object-side surface and the image-side surface of the eighth lens are concave surfaces.

[0011] According to an exemplary embodiment of the present application, the eighth lens has positive refractive power, and both the object-side surface and the image-side surface of the eighth lens are convex surfaces.

[0012] According to an exemplary embodiment of the present application, the ninth lens element has positive refractive power, and both the object-side surface and the image-side surface of the ninth lens element are convex surfaces.

[0013] According to an exemplary embodiment of the present application, the ninth lens element has negative refractive power, and both the object-side surface and the image-side surface of the ninth lens element are concave surfaces.

[0014] According to an exemplary embodiment of the present application, the fourth lens and the fifth lens are cemented to form a cemented lens.

[0015] According to an exemplary embodiment of the present application, the sixth lens and the seventh lens are cemented to form a cemented lens.

[0016] 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: -2.1≤F1 / F≤-1.62.

[0017] According to an exemplary embodiment of the present application, a curvature radius R21 of the object side surface of the second lens, a curvature radius R22 of the image side surface of the second lens, and a total effective focal length F of the fixed focus lens satisfy: -1.5≤(R21+R22) / F≤-1.25.

[0018] According to an exemplary embodiment of the present application, a curvature radius R31 of the object side surface of the third lens, a curvature radius R32 of the image side surface of the third lens, and a total effective focal length F of the fixed focus lens satisfy: 2.82≤(R31+R32) / F≤3.17.

[0019] According to an exemplary embodiment of the present application, a curvature radius R81 of the object side surface of the eighth lens, a curvature radius R82 of the image side surface of the eighth lens, and a total effective focal length F of the fixed focus lens satisfy: 0.86≤|(R81+R82) / F|≤8.73.

[0020] According to an exemplary embodiment of the present application, a curvature radius R91 of the object side surface of the ninth lens, a curvature radius R92 of the image side surface of the ninth lens, and a total effective focal length F of the fixed focus lens satisfy: -11≤(R91+R92) / F≤-1.82.

[0021] According to an exemplary embodiment of the present application, the Abbe number V4 of the fourth lens, the Abbe number V5 of the fifth lens and the total effective focal length F of the fixed-focus lens satisfy: -2.57 mm -1 ≤(V5-V4) / F≤2.63mm -1 .

[0022] According to an exemplary embodiment of the present application, the Abbe number V6 of the sixth lens, the Abbe number V7 of the seventh lens and the total effective focal length F of the fixed-focus lens satisfy: 9.66 mm -1 ≤(V7-V6) / F≤11.76mm -1 .

[0023] According to an exemplary embodiment of the present application, the combined focal length F45 of the fourth lens and the fifth lens and the total effective focal length F of the fixed focus lens satisfy: 2.75≤F45 / F≤4.11.

[0024] 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: 2.34≤|F8 / F|≤4.24.

[0025] According to an exemplary embodiment of the present application, the effective focal length F9 of the ninth lens and the effective focal length F of the fixed focus lens satisfy: 2.38≤|F9 / F|≤5.44.

[0026] According to an exemplary embodiment of the present application, the combined focal length F89 of the eighth lens and the ninth lens and the combined focal length F123 of the first lens to the third lens satisfy: -2.88≤F89 / F123≤-1.83.

[0027] According to an exemplary embodiment of the present application, the total effective focal length F of the fixed-focus lens and the entrance pupil diameter EPD of the fixed-focus lens satisfy: 1≤F / EPD≤1.10.

[0028] According to an exemplary embodiment of the present application, the total optical length TTL of the fixed-focus lens and the total effective focal length F of the fixed-focus lens satisfy: 4.98≤TTL / F≤6.13.

[0029] According to an exemplary embodiment of the present application, the total optical length TTL of the fixed-focus lens and the back focal length BFL of the fixed-focus lens satisfy: 0.19≤BFL / TTL≤0.23.

[0030] The present application adopts nine lenses, and by reasonably allocating the refractive power of each lens, the fixed-focus lens can achieve at least one of the beneficial effects of large aperture, miniaturization, low cost, high resolution, infrared confocality, and athermalization. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0032] Figure 1 A schematic structural diagram of a fixed-focus lens according to Embodiment 1 of the present application is shown;

[0033] Figure 2 A schematic structural diagram of a fixed-focus lens according to Embodiment 2 of the present application is shown;

[0034] Figure 3 A schematic structural diagram of a fixed-focus lens according to Embodiment 3 of the present application is shown; and

[0035] Figure 4 A schematic structural diagram of a fixed-focus lens according to Embodiment 4 of the present application is shown. DETAILED DESCRIPTION

[0036] 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 do not limit the scope of the present application in any way.

[0037] In the 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 shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0038] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface 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 position of the concave surface 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 object is called the object side of the lens, and the surface of each lens closest to the imaging plane is called the image side of the lens.

[0039] It should also be understood that the terms "include", "comprising", "having", "including" and / or "comprising", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. It should be noted that in this specification, the expressions first, second, third, etc. are only used to distinguish one feature from another, and do not represent any limitation on the features.

[0040] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. Terms should be interpreted as having the same meaning as they have in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present 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.

[0042] The fixed focus lens according to an exemplary embodiment of the present application may include a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens, and the nine lenses are arranged in sequence from the object side to the image plane along the optical axis.

[0043] In an exemplary embodiment, the first lens may have a negative refractive power. The object side surface of the first lens may be a convex surface, and the image side surface may be a concave surface. The first lens is designed as a meniscus-shaped negative lens with a convex surface facing the object side, which can gather as much light of a large field of view as possible into the system, which is conducive to improving the field of view angle of the fixed focus lens. The maximum field of view angle of the fixed focus lens can be greater than or equal to 102°.

[0044] In an exemplary embodiment, the second lens may have a positive refractive power. The object side surface of the second lens may be a concave surface, and the image side surface may be a convex surface. The second lens is designed as a concave-convex positive lens, which can effectively control the trend of light, reduce the aberration and spherical aberration of the fixed-focus lens, and improve the image quality of the fixed-focus lens.

[0045] In an exemplary embodiment, the third lens may have a positive refractive power. The object side surface of the third lens may be a convex surface, and the image side surface may be a concave surface. The third lens is designed as a convex-concave positive lens, which can effectively control the light to smoothly enter the rear of the optical system, reduce the spherical aberration of the fixed-focus lens, and improve the imaging quality of the fixed-focus lens.

[0046] In an exemplary embodiment, the fourth lens may have a positive refractive power. The object side surface of the fourth lens may be a convex surface, and the image side surface may be a convex surface. The fourth lens is designed as a biconvex positive lens, which is matched with the fifth lens having a negative refractive power and a concave-convex lens shape to form a double cemented lens, which is conducive to correcting chromatic aberration and improving the imaging quality of the fixed-focus lens; at the same time, it can also smoothly transmit light, reduce the tolerance sensitivity of the fixed-focus lens, and improve the assembly yield of the fixed-focus lens.

[0047] In an exemplary embodiment, the fourth lens may have a negative refractive power. The object side surface of the fourth lens may be a convex surface, and the image side surface may be a concave surface. The fourth lens is designed as a convex-concave negative lens, which is matched with the fifth lens having a positive refractive power and a convex-convex lens shape to form a double cemented lens, which is conducive to correcting chromatic aberration and improving the imaging quality of the fixed-focus lens; at the same time, it can also smoothly transmit light, reduce the tolerance sensitivity of the fixed-focus lens, and improve the assembly yield of the fixed-focus lens.

[0048] In an exemplary embodiment, the fifth lens may have a negative refractive power. The object side surface of the fifth lens may be a concave surface, and the image side surface may be a convex surface. The fifth lens is designed as a concave-convex negative lens, which is matched with the fourth lens having a positive refractive power and a convex-convex lens shape to form a double cemented lens, which can effectively control the trend of light and converge light; at the same time, it can also increase the aperture of the fixed-focus lens, shorten the total optical length of the fixed-focus lens, and make the structure of the fixed-focus lens more compact.

[0049] In an exemplary embodiment, the fifth lens may have a positive refractive power. The object side surface of the fifth lens may be a convex surface, and the image side surface may be a convex surface. The fifth lens is designed as a biconvex positive lens, which is matched with the fourth lens having a negative refractive power and a convex-concave lens shape to form a double cemented lens, which can effectively control the trend of light and converge light; at the same time, it can also increase the aperture of the fixed-focus lens, shorten the total optical length of the fixed-focus lens, and make the structure of the fixed-focus lens more compact.

[0050] In an exemplary embodiment, the sixth lens may have a negative refractive power. The object side surface of the sixth lens may be a convex surface, and the image side surface may be a concave surface. The sixth lens is designed as a convex-concave negative lens, which is matched with the seventh lens having a positive refractive power and a convex-convex lens shape to form a double cemented lens, which can effectively control the trend of light and converge light; at the same time, chromatic aberration can be corrected to improve the imaging quality of the fixed-focus lens.

[0051] In an exemplary embodiment, the seventh lens may have a positive refractive power. The object side surface of the seventh lens may be a convex surface, and the image side surface may be a convex surface. The seventh lens is designed as a biconvex positive lens, which is matched with the sixth lens having a negative refractive power and a convex-concave lens shape to form a double cemented lens, which can effectively control the trend of light and converge light; at the same time, it can also increase the aperture of the fixed-focus lens, shorten the total optical length of the fixed-focus lens, and make the structure of the fixed-focus lens more compact.

[0052] In an exemplary embodiment, the eighth lens may have a negative refractive power. The object side surface of the eighth lens may be a concave surface, and the image side surface may be a concave surface. The eighth lens is designed as a biconcave negative lens, which is matched with the ninth lens having a positive refractive power and a convex-convex lens shape, so that the light can be smoothly transitioned, while reducing various aberrations of the fixed-focus lens and reducing the tolerance sensitivity of the fixed-focus lens, thereby improving the assembly yield of the fixed-focus lens; at the same time, the light can be compressed, the light beam can be tightened, and the chief ray angle (CRA) of the fixed-focus lens can be reduced to match the CRA curve requirements of the rear chip.

[0053] In an exemplary embodiment, the eighth lens may have a positive refractive power. The object side surface of the eighth lens may be a convex surface, and the image side surface may be a convex surface. The eighth lens is designed as a biconvex positive lens, which is matched with the ninth lens having a negative refractive power and a concave lens shape, so that the light can be smoothly transitioned, while reducing various aberrations of the fixed-focus lens and reducing the tolerance sensitivity of the fixed-focus lens, thereby improving the assembly yield of the fixed-focus lens; at the same time, the light can be compressed, the light beam can be tightened, and the chief ray angle (CRA) of the fixed-focus lens can be reduced to match the CRA curve requirements of the rear chip.

[0054] In an exemplary embodiment, the ninth lens may have a negative refractive power. The object side surface of the ninth lens may be a concave surface, and the image side surface may be a concave surface. The ninth lens is designed as a double concave negative lens, which is matched with the eighth lens having a positive refractive power and a convex-convex lens shape, and can effectively compress the light, tighten the light beam, and reduce the CRA angle of the fixed focus lens to match the CRA curve requirements of the rear chip.

[0055] In an exemplary embodiment, the ninth lens may have a positive refractive power. The object side surface of the ninth lens may be a convex surface, and the image side surface may be a convex surface. The ninth lens is designed as a biconvex positive lens, which is matched with the eighth lens having a negative refractive power and a concave-concave lens shape, which can effectively compress the light, tighten the light beam, and reduce the CRA angle of the fixed focus lens to match the CRA curve requirements of the rear chip.

[0056] In an exemplary embodiment, the fourth lens, the fifth lens, the sixth lens, and the seventh lens may be glass lenses. The first lens, the second lens, the third lens, the eighth lens, and the ninth lens may be plastic lenses. The use of a mixture of glass lenses and plastic lenses can reduce the cost of fixed-focus lenses, and can balance the high and low temperature performance of fixed-focus lenses, so that the fixed-focus lenses are not out of focus in the range of -40°C to 80°C and have good imaging quality. In addition, the use of glass lenses is also beneficial for correcting the chromatic aberration of fixed-focus lenses, improving the color saturation of fixed-focus lenses, and is conducive to achieving visible light and infrared confocality.

[0057] In an exemplary embodiment, the fixed-focus lens may further include an aperture. The aperture is disposed between the second lens and the third lens, or between the third lens and the fourth lens. In other examples, the aperture may be disposed on the object side of the third lens, or on the object side of the fourth lens. By providing the aperture, the light entering the system can be effectively converged, the total optical length of the fixed-focus lens can be shortened, and the maximum aperture of the front and rear lens groups can be reduced.

[0058] 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: -2.1≤F1 / F≤-1.62. Reasonable configuration of the effective focal length of the first lens is conducive to converging large-angle light into the system and improving the field of view of the fixed-focus lens. The maximum field of view FOV of the fixed-focus lens can satisfy: FOV≥102°.

[0059] In an exemplary embodiment, the curvature radius R21 of the object side surface of the second lens, the curvature radius R22 of the image side surface of the second lens and the total effective focal length F of the fixed-focus lens can satisfy: -1.5≤(R21+R22) / F≤-1.25. Reasonable configuration of the curvature radii of the object side surface and the image side surface of the second lens is conducive to converging light from different fields of view, effectively ensuring the maximum light throughput of the fixed-focus lens, and improving the image brightness behind the fixed-focus lens; at the same time, it is also conducive to reducing the aberration of the system, balancing the spherical aberration of the system, and improving the imaging quality of the fixed-focus lens.

[0060] In an exemplary embodiment, the curvature radius R31 of the object side surface of the third lens, the curvature radius R32 of the image side surface of the third lens and the total effective focal length F of the fixed focus lens can satisfy: 2.82≤(R31+R32) / F≤3.17. Reasonable configuration of the curvature radii of the object side surface and the image side surface of the third lens can enable the third lens to well receive the light beam emitted from the second lens, and compensate for the spherical aberration generated by the first lens and the second lens, and further correct the aberration generated by the first lens and the second lens.

[0061] In an exemplary embodiment, the curvature radius R81 of the object side surface of the eighth lens, the curvature radius R82 of the image side surface of the eighth lens and the total effective focal length F of the fixed-focus lens can satisfy: 0.86≤|(R81+R82) / F|≤8.73. Reasonable configuration of the curvature radius of the object side surface and the image side surface of the eighth lens is conducive to controlling the height of the light on the object side surface of the eighth lens, and compressing and converging the light, which is conducive to reducing the aberration of the system and reducing the outer diameters of the eighth lens and the ninth lens; at the same time, the field curvature generated by the lens located between the object side and the aperture can be corrected to improve the imaging quality of the fixed-focus lens.

[0062] In an exemplary embodiment, the curvature radius R91 of the object side surface of the ninth lens, the curvature radius R92 of the image side surface of the ninth lens, and the total effective focal length F of the fixed-focus lens can satisfy: -11≤(R91+R92) / F≤-1.82. Reasonable configuration of the curvature radii of the object side surface and the image side surface of the ninth lens can better correct the aberrations generated by the first lens to the eighth lens, improve the high-order spherical aberration and coma of the fixed-focus lens, and facilitate the realization of high resolution of the fixed-focus lens, so that the overall resolution of the fixed-focus lens is uniform.

[0063] In an exemplary embodiment, the Abbe number V4 of the fourth lens, the Abbe number V5 of the fifth lens, and the total effective focal length F of the fixed-focus lens may satisfy: -2.57 mm -1 ≤(V5-V4) / F≤2.63mm -1 Reasonable configuration of the ratio of the difference between the Abbe numbers of the fifth lens and the fourth lens to the total effective focal length of the fixed-focus lens is conducive to balancing chromatic aberration, improving the imaging quality of the fixed-focus lens, and achieving infrared confocality of the fixed-focus lens.

[0064] In an exemplary embodiment, the Abbe number V6 of the sixth lens, the Abbe number V7 of the seventh lens, and the total effective focal length F of the fixed focus lens may satisfy: 9.66 mm -1 ≤(V7-V6) / F≤11.76mm -1 Reasonable configuration of the ratio of the difference between the Abbe numbers of the seventh lens and the sixth lens to the total effective focal length of the fixed-focus lens is conducive to balancing chromatic aberration, improving the imaging quality of the fixed-focus lens, and achieving infrared confocality of the fixed-focus lens.

[0065] In an exemplary embodiment, the combined focal length F45 of the fourth lens and the fifth lens and the total effective focal length F of the fixed-focus lens can satisfy: 2.75≤F45 / F≤4.11. Reasonable configuration of the combined focal length of the fourth lens and the fifth lens is conducive to balancing various aberrations generated by light passing through the aperture, improving the imaging quality of the fixed-focus lens, and achieving a large aperture of the fixed-focus lens. The minimum aperture number Fno of the fixed-focus lens can be 1.05.

[0066] In an exemplary embodiment, the combined focal length F67 of the sixth lens and the seventh lens and the total effective focal length F of the fixed-focus lens can satisfy: 2.62≤F67 / F≤3.53. Reasonable configuration of the combined focal length of the sixth lens and the seventh lens is conducive to balancing various aberrations generated by light passing through the aperture, improving the imaging quality of the fixed-focus lens, and achieving a large aperture of the fixed-focus lens. The minimum aperture number Fno of the fixed-focus lens can be 1.05.

[0067] 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 may satisfy: 2.34≤|F8 / F|≤4.24. Reasonable configuration of the effective focal length of the eighth lens is conducive to smooth transition of light, correction of chromatic aberration and various aberrations of the fixed-focus lens, and improvement of the resolution of the fixed-focus lens; it is also conducive to reducing the tolerance sensitivity of the fixed-focus lens and improving the assembly yield of the fixed-focus lens.

[0068] In an exemplary embodiment, the effective focal length F9 of the ninth lens and the effective focal length F of the fixed-focus lens may satisfy: 2.38≤|F9 / F|≤5.44. Reasonable configuration of the effective focal length of the ninth lens is conducive to smooth transition of light, correction of chromatic aberration and various aberrations of the fixed-focus lens, and improvement of the resolution of the fixed-focus lens; it is also conducive to reducing the tolerance sensitivity of the fixed-focus lens and improving the assembly yield of the fixed-focus lens.

[0069] In an exemplary embodiment, the combined focal length F89 of the eighth lens and the ninth lens and the combined focal length F123 of the first lens to the third lens may satisfy: -2.88≤F89 / F123≤-1.83. Reasonable configuration of the ratio of the combined focal length of the eighth lens and the ninth lens to the combined focal length of the first lens to the third lens is conducive to reducing the focal length variation of the fixed-focus lens at different temperatures, ensuring that the fixed-focus lens is not out of focus within a temperature range of -40°C to 80°C, and achieving athermalization of the fixed-focus lens.

[0070] In an exemplary embodiment, the total effective focal length F of the fixed-focus lens and the entrance pupil diameter EPD of the fixed-focus lens may satisfy: 1≤F / EPD≤1.10. Reasonable configuration of the ratio of the total effective focal length of the fixed-focus lens to the entrance pupil diameter is conducive to achieving a large aperture of the fixed-focus lens.

[0071] In an exemplary embodiment, the total optical length TTL of the fixed-focus lens and the total effective focal length F of the fixed-focus lens may satisfy: 4.98≤TTL / F≤6.13. By rationally configuring the ratio of the total optical length to the total effective focal length of the fixed-focus lens, the total optical length of the fixed-focus lens can be constrained within a certain range when the total effective focal length of the fixed-focus lens is constant, which is conducive to miniaturization of the fixed-focus lens. The total optical length TTL of the fixed-focus lens may satisfy: TTL≤23.06mm.

[0072] In an exemplary embodiment, the total optical length TTL of the fixed-focus lens and the back focal length BFL of the fixed-focus lens may satisfy: 0.19≤BFL / TTL≤0.23. Reasonable configuration of the ratio of the back focal length of the fixed-focus lens to the total optical length can enable the fixed-focus lens to have a long back focal length while achieving miniaturization, which is conducive to providing a larger assembly space for other optical elements, facilitating the assembly of the fixed-focus lens, avoiding interference between optical elements, and improving the assembly yield of the fixed-focus lens.

[0073] The fixed-focus lens according to the above-mentioned embodiment of the present application can use multiple lenses, such as the nine lenses mentioned above, and by reasonably allocating the optical parameters such as the refractive power, surface shape, center thickness of each lens, and the on-axis spacing between each lens, it is possible to achieve at least one of the following: large aperture, miniaturization, low cost, high resolution, infrared confocality, and athermalization of the fixed-focus lens. The fixed-focus lens provided by the present application has good infrared confocality and good infrared imaging effect at night, and is an imaging lens for both day and night use.

[0074] In an embodiment of the present application, at least one of the surfaces of each lens from the first lens to the ninth lens is an aspherical surface. The characteristic of an aspherical lens is that the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. After adopting an aspherical lens, the aberration occurring during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0075] Those skilled in the art should understand that the total optical length TTL of the fixed-focus lens used above refers to the on-axis distance from the object side of the first lens to the imaging plane; the back focal length BFL of the fixed-focus lens refers to the on-axis distance from the image side of the ninth lens to the imaging plane.

[0076] However, those skilled in the art should understand that, without departing from the technical solution claimed in the present application, the number of lenses constituting the fixed-focus lens can be changed to obtain the various results and advantages described in this specification.

[0077] Specific embodiments of the fixed-focus lens applicable to the above-mentioned embodiments are further described below with reference to the accompanying drawings.

[0078] Example 1

[0079] The following reference Figure 1 A fixed-focus lens according to Embodiment 1 of the present application is described. Figure 1 Schematic diagram of the structure of a fixed-focus lens according to Example 1 of the present application.

[0080] like Figure 1As shown, the fixed focus lens 100 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8 and a ninth lens L9 in order from the object side to the imaging surface IMAGE along the optical axis. The aperture STO can be arranged between the second lens L2 and the third lens L3, and is specifically arranged on the object side of the third lens L3. The fourth lens L4 and the fifth lens L5 are cemented to form a cemented lens. The sixth lens L6 and the seventh lens L7 are cemented to form a cemented lens.

[0081] The first lens L1 has negative refractive power, and its object-side surface S1 is convex, and its image-side surface S2 is concave.

[0082] The second lens L2 has positive refractive power, and its object-side surface S3 is concave, and its image-side surface S4 is convex.

[0083] The third lens L3 has positive refractive power, an object-side surface S5 thereof is convex, and an image-side surface S6 thereof is concave.

[0084] The fourth lens L4 has positive refractive power, and its object-side surface S7 is convex and its image-side surface is convex.

[0085] The fifth lens L5 has negative refractive power, and its object-side surface S8 is concave, and its image-side surface S9 is convex.

[0086] The sixth lens L6 has negative refractive power, and its object-side surface S10 is convex, and its image-side surface is concave.

[0087] The seventh lens L7 has positive refractive power, and its object-side surface S11 is convex, and its image-side surface S12 is convex.

[0088] The eighth lens L8 has negative refractive power, and its object-side surface S13 is concave, and its image-side surface S14 is concave.

[0089] The ninth lens L9 has positive refractive power, and its object-side surface S15 is convex, and its image-side surface S16 is convex.

[0090] A filter CG may be further included between the ninth lens L9 and the imaging surface IMAGE. The filter CG has an object side surface S17 and an image side surface S18. Light from the object passes through the surfaces S1 to S18 in sequence and is finally imaged on the imaging surface IMA. It should be noted that the surfaces S1 to S18 are Figure 1 Not shown.

[0091] Table 1 shows basic parameters of the fixed-focus lens 100 of Example 1, wherein the units of the curvature radius, thickness / distance and focal length are all millimeters (mm).

[0092]

[0093]

[0094] Table 1

[0095] In this embodiment, the object side surface and the image side surface of any lens among the first lens L1 to the third lens L3, the eighth lens L8 and the ninth lens L9 are all aspherical surfaces, and the surface shape x of each aspherical lens can be defined by but not limited to the following aspherical surface formula:

[0096]

[0097] Wherein, x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is 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 curvature radius R in Table 1 above); k is the cone coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. Table 2 shows the cone coefficient k and the high-order coefficient A of each aspheric surface S1-S6, S13-S16 that can be used in Example 1 4 , A 6 , A 8 , A 10 , A 12 , A 14 and A 16 .

[0098] Face number K A4 A6 A8 A10 A12 A14 A16 S1 -24.78 -1.46E-03 1.36E-04 -5.53E-06 8.75E-08 0.00E+00 0.00E+00 0.00E+00 S2 -1.54 -1.83E-03 1.57E-03 -2.18E-04 1.75E-05 1.01E-06 -2.61E-07 1.33E-08 S3 -0.34 1.39E-02 -1.33E-03 1.55E-04 -3.25E-06 -3.09E-07 -8.53E-09 4.52E-09 S4 -0.89 5.57E-03 -5.33E-04 2.12E-05 2.30E-07 -1.08E-07 6.50E-09 -3.53E-10 S5 -10.32 -6.66E-05 -7.40E-05 5.16E-06 -1.81E-07 5.39E-10 4.19E-10 -9.72E-12 S6 -20.51 -1.64E-03 4.99E-05 -3.02E-08 -1.82E-07 1.26E-08 -1.70E-10 -9.41E-14 S13 40.41 2.06E-03 -1.06E-04 -2.40E-06 4.91E-07 6.38E-09 1.18E-09 -4.65E-11 S14 19.33 1.02E-03 -8.98E-05 -1.54E-05 -6.44E-07 8.74E-08 9.54E-09 -6.09E-10 S15 -4.43 8.27E-05 -2.66E-05 -1.77E-05 -1.06E-07 -1.78E-08 8.37E-09 -2.61E-10 S16 -29.34 7.02E-04 -2.48E-04 2.65E-05 -1.88E-06 -9.79E-08 1.78E-08 -6.70E-10

[0099] Table 2

[0100] Example 2

[0101] The following reference Figure 2 A fixed-focus lens according to Embodiment 2 of the present application is described. Figure 2 Schematic diagram of the structure of a fixed-focus lens according to Example 2 of the present application.

[0102] like Figure 2 As shown, the fixed focus lens 200 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8 and a ninth lens L9 in order from the object side to the imaging surface IMAGE along the optical axis. The aperture STO can be arranged between the second lens L2 and the third lens L3, and is specifically arranged on the object side of the third lens L3. The fourth lens L4 and the fifth lens L5 are cemented to form a cemented lens. The sixth lens L6 and the seventh lens L7 are cemented to form a cemented lens.

[0103] The first lens L1 has negative refractive power, and its object-side surface S1 is convex, and its image-side surface S2 is concave.

[0104] The second lens L2 has positive refractive power, and its object-side surface S3 is concave, and its image-side surface S4 is convex.

[0105] The third lens L3 has positive refractive power, an object-side surface S5 thereof is convex, and an image-side surface S6 thereof is concave.

[0106] The fourth lens L4 has positive refractive power, and its object-side surface S7 is convex and its image-side surface is convex.

[0107] The fifth lens L5 has negative refractive power, and its object-side surface S8 is concave, and its image-side surface S9 is convex.

[0108] The sixth lens L6 has negative refractive power, and its object-side surface S10 is convex, and its image-side surface is concave.

[0109] The seventh lens L7 has positive refractive power, and its object-side surface S11 is convex, and its image-side surface S12 is convex.

[0110] The eighth lens L8 has positive refractive power, and its object-side surface S13 is convex, and its image-side surface S14 is convex.

[0111] The ninth lens L9 has negative refractive power, and its object-side surface S15 is concave, and its image-side surface S16 is concave.

[0112] A filter CG may be further included between the ninth lens L9 and the imaging surface IMAGE. The filter CG has an object side surface S17 and an image side surface S18. Light from the object passes through the surfaces S1 to S18 in sequence and is finally imaged on the imaging surface IMA. It should be noted that the surfaces S1 to S18 are Figure 2 Not shown.

[0113] Table 3 shows basic parameters of the fixed-focus lens 200 of Example 2, wherein the units of the curvature radius, thickness / distance and focal length are all millimeters (mm).

[0114]

[0115] Table 3

[0116] In this embodiment, the object side surface and the image side surface of any one of the first lens L1 to the third lens L3, the eighth lens L8 and the ninth lens L9 are all aspherical surfaces. Table 4 shows the cone coefficient k and the high-order coefficient A of each aspherical surface S1-S6, S13-S16 that can be used in Example 2 4 , A 6 , A 8 , A 10 , A 12 , A 14 and A 16 .

[0117] Face number K A4 A6 A8 A10 A12 A14 A16 S1 -25.81 -2.19E-03 1.49E-04 -4.84E-06 6.45E-08 0.00E+00 0.00E+00 0.00E+00 S2 -1.56 -2.79E-03 1.42E-03 -2.24E-04 1.82E-05 1.04E-06 -2.57E-07 1.19E-08 S3 -0.37 1.54E-02 -1.30E-03 1.50E-04 -3.38E-06 -3.10E-07 -1.05E-08 3.68E-09 S4 -1.00 6.23E-03 -4.71E-04 2.17E-05 1.06E-07 -1.40E-07 5.18E-09 -1.06E-10 S5 -11.90 -1.30E-04 -7.85E-05 4.70E-06 -2.18E-07 -7.94E-10 3.39E-10 -5.04E-12 S6 -18.58 -1.65E-03 4.42E-05 -3.64E-07 -1.94E-07 1.22E-08 -1.96E-10 -1.45E-12 S13 -3.32 -9.50E-05 -2.18E-06 -1.07E-05 1.57E-07 -6.22E-08 8.37E-09 -2.61E-10 S14 -56.58 7.81E-04 -2.71E-04 2.61E-05 -1.71E-06 -8.51E-08 1.78E-08 -6.70E-10 S15 27.62 2.30E-03 -3.04E-05 1.36E-06 3.85E-07 -2.01E-08 -6.04E-10 -6.78E-11 S16 22.49 1.61E-03 1.80E-05 -3.96E-06 -3.41E-07 4.45E-08 3.32E-09 -9.21E-10

[0118] Table 4

[0119] Example 3

[0120] The following reference Figure 3 A fixed-focus lens according to Example 3 of the present application is described. Figure 3 Schematic diagram of the structure of a fixed-focus lens according to Example 3 of the present application.

[0121] like Figure 3 As shown, the fixed focus lens 300 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8 and a ninth lens L9 in order from the object side to the imaging surface IMAGE along the optical axis. The aperture STO can be arranged between the third lens L3 and the fourth lens L4, and is specifically arranged on the object side of the fourth lens L4. The fourth lens L4 and the fifth lens L5 are cemented to form a cemented lens. The sixth lens L6 and the seventh lens L7 are cemented to form a cemented lens.

[0122] The first lens L1 has negative refractive power, and its object-side surface S1 is convex, and its image-side surface S2 is concave.

[0123] The second lens L2 has positive refractive power, and its object-side surface S3 is concave, and its image-side surface S4 is convex.

[0124] The third lens L3 has positive refractive power, an object-side surface S5 thereof is convex, and an image-side surface S6 thereof is concave.

[0125] The fourth lens L4 has negative refractive power, and its object-side surface S7 is convex and its image-side surface is concave.

[0126] The fifth lens L5 has positive refractive power, and its object-side surface S8 is convex, and its image-side surface S9 is convex.

[0127] The sixth lens L6 has negative refractive power, and its object-side surface S10 is convex, and its image-side surface is concave.

[0128] The seventh lens L7 has positive refractive power, and its object-side surface S11 is convex, and its image-side surface S12 is convex.

[0129] The eighth lens L8 has negative refractive power, and its object-side surface S13 is concave, and its image-side surface S14 is concave.

[0130] The ninth lens L9 has positive refractive power, and its object-side surface S15 is convex, and its image-side surface S16 is convex.

[0131] A filter CG may be further included between the ninth lens L9 and the imaging surface IMAGE. The filter CG has an object side surface S17 and an image side surface S18. Light from the object passes through the surfaces S1 to S18 in sequence and is finally imaged on the imaging surface IMA. It should be noted that the surfaces S1 to S18 are Figure 3 Not shown.

[0132] Table 5 shows basic parameters of the fixed-focus lens 300 of Example 3, wherein the units of the curvature radius, thickness / distance and focal length are all millimeters (mm).

[0133]

[0134]

[0135] Table 5

[0136] In this embodiment, the object side surface and the image side surface of any one of the first lens L1 to the third lens L3, the eighth lens L8 and the ninth lens L9 are all aspherical surfaces. Table 6 shows the cone coefficient k and the high-order coefficient A of each aspherical surface S1-S6, S13-S16 that can be used in Example 3 4 , A 6 , A 8 , A 10 , A 12 , A 14 and A 16 .

[0137] Face number K A4 A6 A8 A10 A12 A14 A16 S1 -54.00 -1.89E-03 1.38E-04 -4.98E-06 7.49E-08 0.00E+00 0.00E+00 0.00E+00 S2 -1.49 -2.14E-03 1.50E-03 -2.19E-04 1.62E-05 1.12E-06 -2.47E-07 1.21E-08 S3 -0.35 1.41E-02 -1.35E-03 1.55E-04 -3.14E-06 -3.02E-07 -1.02E-08 3.79E-09 S4 -0.90 5.68E-03 -5.26E-04 2.14E-05 2.44E-07 -1.06E-07 6.42E-09 -4.49E-10 S5 -10.19 -3.58E-05 -7.29E-05 5.15E-06 -1.87E-07 1.38E-10 4.04E-10 -1.01E-11 S6 -21.88 -1.68E-03 4.82E-05 -6.09E-08 -1.82E-07 1.26E-08 -1.82E-10 -1.14E-12 S13 39.10 2.08E-03 -1.09E-04 -2.64E-06 4.72E-07 4.54E-09 1.01E-09 -5.99E-11 S14 19.32 1.02E-03 -8.38E-05 -1.51E-05 -6.53E-07 8.48E-08 9.26E-09 -6.68E-10 S15 -5.50 -1.25E-04 -4.34E-05 -1.86E-05 -1.56E-07 -2.35E-08 7.91E-09 -2.14E-10 S16 42.10 5.72E-04 -2.60E-04 2.52E-05 -1.92E-06 -9.27E-08 1.84E-08 -6.76E-10

[0138] Table 6

[0139] Example 4

[0140] The following reference Figure 4 A fixed-focus lens according to Example 4 of the present application is described. Figure 4 Schematic diagram of the structure of a fixed-focus lens according to Example 4 of the present application.

[0141] like Figure 4 As shown, the fixed focus lens 400 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8 and a ninth lens L9 in order from the object side to the imaging surface IMAGE along the optical axis. The aperture STO can be arranged between the second lens L2 and the third lens L3, and is specifically arranged on the object side of the third lens L3. The fourth lens L4 and the fifth lens L5 are cemented to form a cemented lens. The sixth lens L6 and the seventh lens L7 are cemented to form a cemented lens.

[0142] The first lens L1 has negative refractive power, and its object-side surface S1 is convex, and its image-side surface S2 is concave.

[0143] The second lens L2 has positive refractive power, and its object-side surface S3 is concave, and its image-side surface S4 is convex.

[0144] The third lens L3 has positive refractive power, an object-side surface S5 thereof is convex, and an image-side surface S6 thereof is concave.

[0145] The fourth lens L4 has negative refractive power, and its object-side surface S7 is convex and its image-side surface is concave.

[0146] The fifth lens L5 has positive refractive power, and its object-side surface S8 is convex, and its image-side surface S9 is convex.

[0147] The sixth lens L6 has negative refractive power, and its object-side surface S10 is convex, and its image-side surface is concave.

[0148] The seventh lens L7 has positive refractive power, and its object-side surface S11 is convex, and its image-side surface S12 is convex.

[0149] The eighth lens L8 has negative refractive power, and its object-side surface S13 is concave, and its image-side surface S14 is concave.

[0150] The ninth lens L9 has positive refractive power, and its object-side surface S15 is convex, and its image-side surface S16 is convex.

[0151] A filter CG may be further included between the ninth lens L9 and the imaging surface IMAGE. The filter CG has an object side surface S17 and an image side surface S18. Light from the object passes through the surfaces S1 to S18 in sequence and is finally imaged on the imaging surface IMA. It should be noted that the surfaces S1 to S18 are Figure 4 Not shown.

[0152] Table 7 shows a basic parameter table of the fixed-focus lens 400 of Example 4, wherein the units of the curvature radius, thickness / distance and focal length are all millimeters (mm).

[0153]

[0154] Table 7

[0155] In this embodiment, the object side surface and the image side surface of any one of the first lens L1 to the third lens L3, the eighth lens L8 and the ninth lens L9 are all aspherical surfaces. Table 8 shows the cone coefficient k and the high-order coefficient A of each aspherical surface S1-S6, S13-S16 that can be used in Example 4 4 , A 6 , A 8 , A 10 , A 12 , A 14and A 16 .

[0156]

[0157]

[0158] Table 8

[0159] In summary, the conditional expressions in Examples 1 to 4 satisfy the relationship shown in Table 9.

[0160] Conditional / Example 1 2 3 4 F1 / F -1.869 -1.907 -1.698 -1.909 (R21+R22) / F -1.384 -1.359 -1.343 -1.440 (R31+R32) / F 3.001 3.121 2.993 3.110 |(R81+R82) / F| 2.003 7.615 1.990 2.079 (R91+R92) / F -8.005 -3.144 -7.368 -8.707 <![CDATA[(V5-V4) / F(mm -1 )]]> -1.821 -1.732 1.757 1.887 <![CDATA[(V7-V6) / F(mm -1 )]]> 11.062 10.522 10.678 11.467 F45 / F 3.765 3.916 3.755 3.920 F67 / F 2.934 2.922 2.751 3.010 F / EPD 1.060 1.070 1.065 1.070 |F8 / F| 3.795 2.764 3.678 3.967 |F9 / F| 2.900 3.936 2.817 2.966 F89 / F123 -2.360 -2.498 -2.725 -2.240 TTL / F 5.762 5.439 5.480 5.973 BFL / TTL 0.204 0.200 0.225 0.203

[0161] Table 9

[0162] 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), and the imaging device is equipped with the fixed-focus lens described above.

[0163] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the utility model involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) by each other.

Claims

1. A fixed-focus lens, characterized in that: Along the optical axis from the object side to the image plane, they include: The first lens has a negative refractive power, and its object side surface is convex and its image side surface is concave; The second lens has a positive refractive power, and its object side surface is concave and its image side surface is convex; The third lens element has a positive refractive power, and its object side surface is convex and its image side surface is concave; a fourth lens element having a refractive power and a convex object side surface; a fifth lens element having a refractive power and having a convex image-side surface; a sixth lens element having negative refractive power, whose object side surface is convex and image side surface is concave; A seventh lens element having positive refractive power, whose object side surface is convex and image side surface is convex; an eighth lens having a refractive power, wherein the object side surface and the image side surface are concave surfaces, or the object side surface and the image side surface are convex surfaces; A ninth lens element having a refractive power, whose object side surface and image side surface are concave surfaces, or whose object side surface and image side surface are convex surfaces; The signs of the diopter of the fourth lens and the fifth lens are opposite in positive and negative properties; the signs of the diopter of the eighth lens and the ninth lens are opposite in positive and negative properties; and The combined focal length F67 of the sixth lens and the seventh lens and the total effective focal length F of the fixed-focus lens satisfy the following: 2.62≤F67 / F≤3.

53.

2. The fixed-focus lens according to claim 1, characterized in that: The fourth lens has positive refractive power, and the image side surface of the fourth lens is a convex surface.

3. The fixed-focus lens according to claim 1, characterized in that: The fourth lens has negative refractive power, and the image side surface of the fourth lens is a concave surface.

4. The fixed-focus lens according to claim 1, characterized in that: The fifth lens element has negative refractive power, and the object side surface of the fifth lens element is a concave surface.

5. The fixed-focus lens according to claim 1, wherein: The fifth lens element has positive refractive power, and the object side surface of the fifth lens element is a convex surface.

6. The fixed-focus lens according to claim 1, wherein: The eighth lens element has negative refractive power, and both the object side surface and the image side surface of the eighth lens element are concave surfaces.

7. The fixed-focus lens according to claim 1, wherein: The eighth lens element has positive refractive power, and both the object side surface and the image side surface of the eighth lens element are convex surfaces.

8. The fixed-focus lens according to claim 1, wherein: The ninth lens element has positive refractive power, and both the object side surface and the image side surface of the ninth lens element are convex surfaces.

9. The fixed-focus lens according to claim 1, wherein: The ninth lens element has negative refractive power, and both the object side surface and the image side surface of the ninth lens element are concave surfaces.

10. The fixed-focus lens according to claim 1, wherein: The fourth lens and the fifth lens are cemented to form a cemented lens.

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

12. The fixed-focus lens according to any one of claims 1 to 11, 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: -2.1≤F1 / F≤-1.

62.

13. The fixed-focus lens according to any one of claims 1 to 11, characterized in that: A curvature radius R21 of the object side surface of the second lens, a curvature radius R22 of the image side surface of the second lens, and a total effective focal length F of the fixed-focus lens satisfy: -1.5≤(R21+R22) / F≤-1.

25.

14. The fixed-focus lens according to any one of claims 1 to 11, characterized in that: A curvature radius R31 of the object side surface of the third lens, a curvature radius R32 of the image side surface of the third lens, and a total effective focal length F of the fixed-focus lens satisfy: 2.82≤(R31+R32) / F≤3.

17.

15. The fixed-focus lens according to any one of claims 1 to 11, characterized in that: A curvature radius R81 of the object side surface of the eighth lens, a curvature radius R82 of the image side surface of the eighth lens, and a total effective focal length F of the fixed-focus lens satisfy: 0.86≤|(R81+R82) / F|≤8.

73.

16. The fixed-focus lens according to any one of claims 1 to 11, characterized in that: A curvature radius R91 of the object side surface of the ninth lens, a curvature radius R92 of the image side surface of the ninth lens, and a total effective focal length F of the fixed-focus lens satisfy: -11≤(R91+R92) / F≤-1.

82.

17. The fixed-focus lens according to any one of claims 1 to 11, characterized in that: The Abbe number V4 of the fourth lens, the Abbe number V5 of the fifth lens and the total effective focal length F of the fixed-focus lens satisfy: -2.57 mm -1 ≤(V5-V4) / F≤2.63mm -1 .

18. The fixed-focus lens according to any one of claims 1 to 11, characterized in that: The Abbe number V6 of the sixth lens, the Abbe number V7 of the seventh lens and the total effective focal length F of the fixed-focus lens satisfy: 9.66 mm -1 ≤(V7-V6) / F≤11.76mm -1 .

19. The fixed-focus lens according to any one of claims 1 to 11, characterized in that: The combined focal length F45 of the fourth lens and the fifth lens and the total effective focal length F of the fixed-focus lens satisfy the following: 2.75≤F45 / F≤4.

11.

20. The fixed-focus lens according to any one of claims 1 to 11, characterized in that: The effective focal length F8 of the eighth lens and the total effective focal length F of the fixed-focus lens satisfy: 2.34≤|F8 / F|≤4.

24.

21. The fixed-focus lens according to any one of claims 1 to 11, characterized in that: The effective focal length F9 of the ninth lens and the effective focal length F of the fixed-focus lens satisfy: 2.38≤|F9 / F|≤5.

44.

22. The fixed-focus lens according to any one of claims 1 to 11, characterized in that: A combined focal length F89 of the eighth lens and the ninth lens and a combined focal length F123 of the first lens to the third lens satisfy: -2.88≤F89 / F123≤-1.

83.

23. The fixed-focus lens according to any one of claims 1 to 11, characterized in that: The total effective focal length F of the fixed-focus lens and the entrance pupil diameter EPD of the fixed-focus lens satisfy: 1≤F / EPD≤1.

10.

24. The fixed-focus lens according to any one of claims 1 to 11, characterized in that: The total optical length TTL of the fixed-focus lens and the total effective focal length F of the fixed-focus lens satisfy the following conditions: 4.98≤TTL / F≤6.

13.

25. The fixed-focus lens according to any one of claims 1 to 11, characterized in that: The total optical length TTL of the fixed-focus lens and the back focal length BFL of the fixed-focus lens satisfy: 0.19≤BFL / TTL≤0.23.

Images