Prime lens

Abstract

The invention discloses a prime lens. The prime lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens from an object side to an image side along an optical axis, the second lens has negative focal power; the third lens has positive focal power; the fourth lens has negative focal power; the fifth lens has positive or negative focal power; the sixth lens has positive or negative focal power; a seventh lens having negative or positive focal power; the eighth lens has negative or positive focal power; the ninth lens has negative focal power; the number of lenses with focal power of the prime lens is nine; wherein the focal power of at least one of the fifth lens and the sixth lens is positive, the focal power of the sixth lens is opposite to that of the seventh lens, and the focal power of the seventh lens is the same as that of the eighth lens; the prime lens meets the condition that 0.58 < = R22 / F2 < = 7.33, R22 is the curvature radius of the image side face of the second lens, and F2 is the effective focal length of the second 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 rise of the drone market, drones are widely used in all walks of life, and the requirements for drone lenses are getting higher and higher. They need to provide all-weather monitoring images, ultra-large aperture to ensure clear imaging even in low light conditions, and no out-of-focus in high and low temperature environments to ensure that the lens still has high imaging quality under harsh weather conditions.

[0003] However, the drone lenses currently on the market still have the following shortcomings:

[0004] 1. The existing lens imaging screen is small and difficult to match with large target surface chips;

[0005] 2. Existing lenses are too long and bulky, which makes the overall cost and weight of the lens too high.

[0006] 3. Existing lenses have difficulty capturing clear images in low-light conditions;

[0007] 4. Large aperture lenses do not have night vision function.

[0008] Therefore, in summary, designing a fixed-focus lens with a large target area, low cost, small size, large aperture and infrared confocality has become a market development trend. Summary of the Invention

[0009] 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 with positive optical power; a second lens with negative optical power; a third lens with positive optical power; a fourth lens with negative optical power; a fifth lens with positive or negative optical power; a sixth lens with positive or negative optical power; a seventh lens with negative or positive optical power; an eighth lens with negative or positive optical power; and a ninth lens with negative optical power. The fixed-focus lens has nine lenses with optical powers. At least one of the fifth and sixth lenses has positive optical power, the sixth and seventh lenses have opposite optical powers, and the seventh and eighth lenses have the same optical power. The fixed-focus lens satisfies the following conditions: 0.58≤R22 / F2≤7.33, where R22 is the radius of curvature of the image-side surface of the second lens, and F2 is the effective focal length of the second lens.

[0010] According to an exemplary embodiment of the present application, the object-side surface of the first lens is convex, and the image-side surface is convex; the object-side surface of the second lens is concave, and the image-side surface is convex; the object-side surface of the third lens is convex, and the image-side surface is concave; and the object-side surface of the fourth lens is convex, and the image-side surface is concave.

[0011] According to an exemplary embodiment of the present application, the object side surface of the fifth lens is convex, and the image side surface is convex, the object side surface of the sixth lens is convex, and the image side surface is convex, the object side surface of the seventh lens is concave, and the image side surface is convex, the object side surface of the eighth lens is concave, and the image side surface is convex, and the object side surface of the ninth lens is concave, and the image side surface is concave; or the object side surface of the fifth lens is convex, and the image side surface is convex, the object side surface of the sixth lens is convex, and the image side surface is convex, the object side surface of the seventh lens is concave, and the image side surface is convex, the object side surface of the eighth lens is concave, and the image side surface is convex, and the object side surface of the ninth lens is convex, and the image side surface is concave; or the object side surface of the fifth lens is convex, and the image side surface is convex, the object side surface of the sixth lens is convex, and the image side surface is convex, The object side surface of the seventh lens is concave, and the image side surface is convex, the object side surface of the eighth lens is convex, and the image side surface is concave, and the object side surface of the ninth lens is convex, and the image side surface is concave; or the object side surface of the fifth lens is convex, and the image side surface is concave, the object side surface of the sixth lens is concave, and the image side surface is convex, the object side surface of the seventh lens is convex, and the image side surface is concave, the object side surface of the eighth lens is concave, and the image side surface is convex, and the object side surface of the ninth lens is convex, and the image side surface is concave; or the object side surface of the fifth lens is convex, and the image side surface is concave, the object side surface of the sixth lens is convex, and the image side surface is convex, the object side surface of the seventh lens is concave, and the image side surface is convex, the object side surface of the eighth lens is concave, and the image side surface is convex, and the object side surface of the ninth lens is convex, and the image side surface is concave.

[0012] According to an exemplary embodiment of the present application, the fixed-focus lens satisfies at least one of the following conditional equations: 0.22≤R32 / F3≤0.61, -15.62≤(R41+R42) / F4≤-0.08, wherein R32 is the radius of curvature of the image-side surface of the third lens element, F3 is the effective focal length of the third lens element, R41 is the radius of curvature of the object-side surface of the fourth lens element, R42 is the radius of curvature of the image-side surface of the fourth lens element, and F4 is the effective focal length of the fourth lens element.

[0013] According to an exemplary embodiment of the present application, the fixed-focus lens satisfies at least one of the following conditional expressions: 0.79≤F1 / F≤1.74, 2.34≤F3 / F≤5.04, 0.36≤F12 / F3≤1.05, -0.34≤F12 / (F3+F4)≤2.53, -10.70≤F5 / F≤1.69, -0.41≤F5 / F6≤0.80, -5.95≤F9 / F≤-0.98, -0.09≤ F5 / (F4+F7+F8+F9)≤0.84, where F1 is the effective focal length of the first lens element, F12 is the combined effective focal length of the first and second lens elements, F3 is the effective focal length of the third lens element, F4 is the effective focal length of the fourth lens element, F5 is the effective focal length of the fifth lens element, F6 is the effective focal length of the sixth lens element, F7 is the effective focal length of the seventh lens element, F8 is the effective focal length of the eighth lens element, F9 is the effective focal length of the ninth lens element, and F is the effective focal length of the fixed-focus lens element.

[0014] According to an exemplary embodiment of the present application, the fixed-focus lens satisfies at least one of the following conditional expressions: 0mm -1 ≤(Nd2-Nd1) / F12≤0.005mm -1 , 0.23mm -1 ≤(V1-V2) / F12≤0.95mm -1 ,0.92mm≤F3 / V3≤1.54mm,-0.25mm -1 ≤V6 / F6≤2.79mm -1 , where Nd1 is the refractive index of the first lens, Nd2 is the refractive index of the second lens, V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, V3 is the Abbe number of the third lens, V6 is the Abbe number of the sixth lens, F12 is the combined effective focal length of the first and second lenses, F3 is the effective focal length of the third lens, and F6 is the effective focal length of the sixth lens.

[0015] According to an exemplary embodiment of the present application, the fixed-focus lens satisfies at least one of the following conditional equations: 1.26≤TTL / F≤1.59, 0.13≤BFL / TTL≤0.20, 0.45≤D1 / TTL≤0.58, and 1.14≤TTL / H≤1.42, where TTL is the total optical length of the fixed-focus lens, BFL is the optical back focus of the fixed-focus lens, H is the full image height of the fixed-focus lens, F is the effective focal length of the fixed-focus lens, and D1 is the maximum effective clear aperture of the first lens.

[0016] According to an exemplary embodiment of the present application, the fixed-focus lens satisfies at least one of the following conditional expressions: 0.64≤R22 / F2≤6.66, 0.25≤R32 / F3≤0.58, 0.88≤F1 / F≤1.58, 2.60≤F3 / F≤4.58, -9.73≤F5 / F≤1.54, -0.37≤F5 / F6≤0.73, 0mm -1 ≤(Nd2-Nd1) / F12≤0.003mm -1 , 0.25mm -1 ≤(V1-V2) / F12≤0.86mm -1 , 1.02mm≤F3 / V3≤1.40mm, 1.40≤TTL / F≤1.44, 0.50≤D1 / TTL≤0.52, 1.27≤TTL / H≤1.29, where R22 is the radius of curvature of the image-side surface of the second lens, F2 is the effective focal length of the second lens, R32 is the radius of curvature of the image-side surface of the third lens, F3 is the effective focal length of the third lens, F1 is the effective focal length of the first lens, F is the effective focal length of the fixed-focus lens, F5 is the effective focal length of the fifth lens, F6 is the effective focal length of the sixth lens, Nd1 is the refractive index of the first lens, Nd2 is the refractive index of the second lens, F12 is the combined effective focal length of the first lens and the second lens, V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, V3 is the Abbe number of the third lens, TTL is the total optical length of the fixed-focus lens, H is the full image height of the fixed-focus lens, and D1 is the maximum effective aperture of the first lens.

[0017] According to an exemplary embodiment of the present application, the fixed-focus lens satisfies at least one of the following conditional expressions: -14.20≤(R41+R42) / F4≤-0.09, 0.40≤F12 / F3≤0.96, -0.31≤F12 / (F3+F4)≤2.30, -5.41≤F9 / F≤-1.09, -0.08≤F5 / (F4+F7+F8+F9)≤0.77, -0.23mm -1 ≤V6 / F6≤2.54mm -1 , 0.14≤BFL / TTL≤0.18, where R41 is the radius of curvature of the object side surface of the fourth lens, R42 is the radius of curvature of the image side surface of the fourth lens, F4 is the effective focal length of the fourth lens, F12 is the combined effective focal length of the first lens and the second lens, F3 is the effective focal length of the third lens, F7 is the effective focal length of the seventh lens, F8 is the effective focal length of the eighth lens, F9 is the effective focal length of the ninth lens, F is the effective focal length of the fixed-focus lens, V6 is the Abbe number of the sixth lens, F6 is the effective focal length of the sixth lens, TTL is the total optical length of the fixed-focus lens, and BFL is the optical back focal length of the fixed-focus lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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:

[0019] Figure 1 1 shows a schematic structural diagram of a fixed-focus lens according to Example 1 of the present application;

[0020] Figure 2 1 shows a schematic structural diagram of a fixed-focus lens according to Example 2 of the present application;

[0021] Figure 3 1 shows a schematic structural diagram of a fixed-focus lens according to Example 3 of the present application;

[0022] Figure 4 1 shows a schematic structural diagram of a fixed-focus lens according to Example 4 of the present application;

[0023] Figure 5 1 shows a schematic structural diagram of a fixed-focus lens according to Example 5 of the present application;

[0024] Figure 6 A structural schematic diagram of a fixed-focus lens according to Example 6 of the present application is shown. DETAILED DESCRIPTION

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] The fixed focus lens according to an exemplary embodiment of the present application may include first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth lenses arranged in order from the object side to the image side along the optical axis.

[0032] In an exemplary embodiment, the first lens may have positive optical power, and its object-side surface and image-side surface may be convex. The first lens having positive optical power, a convex object-side surface, and a convex image-side surface can converge light entering the optical system, shortening the overall optical length of the lens and making the optical system more compact.

[0033] In an exemplary embodiment, the second lens element may have negative power, with its object-side surface being concave and its image-side surface being convex. This negative-power, concave-object-side surface and convex-image-side surface, combined with the first lens element, form a doublet lens with positive power. This effectively controls the trajectory of light, converging the light entering the optical system, shortening the overall lens length and making the optical system more compact.

[0034] In an exemplary embodiment, the third lens element may have positive optical power, and its object-side surface may be convex, while its image-side surface may be concave. This positive optical power, convex object-side surface, and concave image-side surface of the third lens element can effectively reduce chromatic aberration in the optical system, thereby improving the imaging quality of the lens.

[0035] In an exemplary embodiment, the fourth lens element may have negative optical power, and its object-side surface may be convex and its image-side surface may be concave. This negative optical power, convex object-side surface, and concave image-side surface of the fourth lens element can effectively control the direction of incident light in the optical system, reduce optical system aberrations, and improve lens imaging quality.

[0036] In an exemplary embodiment, the fifth lens element may have positive optical power, and its object-side surface may be convex. This positive optical power and convex object-side surface of the fifth lens element effectively control the smooth entry of light into the rear of the optical system, reducing spherical aberration while balancing the optical system's field curvature, thereby improving lens imaging quality. In an exemplary embodiment, the image-side surface of the fifth lens element may be either convex or concave.

[0037] In an exemplary embodiment, the fifth lens element may have negative optical power, and its object-side surface may be convex and its image-side surface may be concave. This negative optical power, convex object-side surface, and concave image-side surface of the fifth lens element effectively control the smooth entry of light into the rear of the optical system, reducing spherical aberration and balancing the field curvature of the optical system, thereby improving lens imaging quality.

[0038] In an exemplary embodiment, the sixth lens element may have positive optical power, and its object-side surface and image-side surface may be convex. This positive optical power, along with both convex object-side and image-side surfaces, effectively reduces chromatic aberration in the optical system, thereby improving lens imaging quality.

[0039] In an exemplary embodiment, the sixth lens element may have negative optical power, and its object-side surface may be concave, while its image-side surface may be convex. This negative optical power, concave object-side surface, and convex image-side surface of the sixth lens element can effectively reduce chromatic aberration in the optical system, thereby improving the imaging quality of the lens.

[0040] In an exemplary embodiment, the seventh lens element may have negative power, and its object-side surface may be concave, while its image-side surface may be convex. The seventh lens element's negative power, concave object-side surface, and convex image-side surface can minimize the transition of light between the lens elements, thereby reducing optical system aberrations and balancing field curvature, thereby improving lens imaging quality.

[0041] In an exemplary embodiment, the seventh lens element may have positive refractive power, with a convex object-side surface and a concave image-side surface. This positive refractive power, convex object-side surface, and concave image-side surface of the seventh lens element can minimize the transition of light between the lens elements, thereby reducing optical system aberrations and balancing field curvature, thereby improving lens imaging quality.

[0042] In exemplary embodiments, the eighth lens element may have negative power, and its object-side surface may be concave and its image-side surface may be convex, or its object-side surface may be convex and its image-side surface may be concave. The eighth lens element having negative power, a concave object-side surface and a convex image-side surface, or both, facilitates correction of peripheral field aberrations and better meets imaging quality requirements.

[0043] In an exemplary embodiment, the eighth lens element may have positive optical power, with its object-side surface being concave and its image-side surface being convex. This positive optical power, concave object-side surface, and convex image-side surface of the eighth lens element facilitate correction of peripheral field aberrations, thereby better meeting imaging quality requirements.

[0044] In an exemplary embodiment, the ninth lens element may have negative refractive power, and its image-side surface may be concave. This negative refractive power and concave image-side surface of the ninth lens element can maximize the convergence of incident light entering the optical system, thereby increasing the principal ray angle of the optical system, improving the illumination of the optical system, and balancing field curvature, thereby enhancing lens imaging quality. In an exemplary embodiment, the object-side surface of the ninth lens element may be either convex or concave.

[0045] In an exemplary embodiment, the fixed-focus lens may further include an aperture. The aperture may be located on the object-side surface of the first lens element or between the object surface and the object-side surface of the first lens element. The aperture can effectively limit the amount of light entering the optical system, shortening the overall optical length of the fixed-focus lens element and reducing the maximum optical aperture of the fixed-focus lens element, thereby facilitating miniaturization of the fixed-focus lens element.

[0046] In an exemplary embodiment, the total optical length TTL of the fixed-focus lens may satisfy: TTL≤36 mm. Further, the TTL may satisfy: 35.0 mm≤TTL≤35.4 mm, thereby achieving the requirement of a small volume for the fixed-focus lens.

[0047] In an exemplary embodiment, the aperture FNO of the fixed-focus lens may satisfy: FNO≤1.4. Further, FNO may satisfy: 1.3≤FNO≤1.4, thereby achieving the large aperture requirement of the fixed-focus lens.

[0048] In an exemplary embodiment, the full image height of the fixed-focus lens may satisfy: H≤28 mm. Further, H may satisfy: 27 mm≤H≤28 mm, thereby achieving the large target surface requirement of the fixed-focus lens.

[0049] In an exemplary embodiment, any of the first through ninth lenses may be glass or plastic. Glass lenses can effectively suppress temperature-induced shifts in the back focal length of fixed-focus lenses, improving their stability. Furthermore, glass lenses can effectively prevent image blur caused by high or low temperature environments, ensuring the proper operation of fixed-focus lenses. This facilitates athermalization of fixed-focus lenses and effectively corrects chromatic aberration in the optical system, improving their resolution. Plastic lenses can effectively reduce the cost of fixed-focus lenses. As an example, among the first to ninth lenses, the first lens, the second lens, the third lens and the sixth lens, or the first lens, the second lens, the fourth lens and the fifth lens, or the first lens, the second lens, the third lens, the fourth lens and the fifth lens, or the first lens, the second lens, the third lens and the fifth lens are glass lenses, and the remaining lenses are plastic lenses, which is beneficial to reducing the cost of fixed-focus lenses and balancing the high and low temperature performance of fixed-focus lenses, achieving no defocus in the range of -20℃ to +70℃ while maintaining high imaging quality. At the same time, the use of glass lenses is beneficial to correcting the chromatic aberration of the optical system, improving the color saturation of the lens, and improving the imaging quality.

[0050] In an exemplary embodiment, the present application uses a combination of spherical lenses and aspherical lenses, which helps to reduce the difficulty of lens processing. The present application does not specifically limit the specific number of spherical lenses and aspherical lenses. When focusing on imaging quality, the number of aspherical lenses can be increased, and even all lenses can use aspherical lenses. The characteristic of aspherical lenses is that the curvature changes continuously from the center of the lens to the periphery. Unlike spherical lenses with constant curvature from the center of the lens to the periphery, aspherical lenses have better curvature radius characteristics, and have the advantages of improving distortion aberration and improving astigmatism aberration. As an example, among the first to ninth lenses, the first lens and the second lens, or the first lens, the second lens and the fourth lens are spherical lenses, and the remaining lenses are all aspherical lenses, which can eliminate the aberrations that occur during imaging as much as possible, thereby improving the imaging quality of the lens.

[0051] In an exemplary embodiment, the fixed-focus lens can satisfy the following equation: -5.95 ≤ F9 / F ≤ -0.98, where F9 is the effective focal length of the ninth lens element and F is the effective focal length of the fixed-focus lens. By ensuring that the fixed-focus lens satisfies this conditional equation and controlling the ratio of the effective focal length of the ninth lens element to the effective focal length of the fixed-focus lens, it is advantageous to correct for chromatic aberration in the optical system caused by the wide-band design, thereby improving lens resolution. Preferably, the fixed-focus lens can further satisfy the following equation: -5.41 ≤ F9 / F ≤ -1.09, further improving lens resolution.

[0052] In an exemplary embodiment, the fixed-focus lens can satisfy the following equation: 2.34 ≤ F3 / F ≤ 5.04, where F3 is the effective focal length of the third lens element, and F is the effective focal length of the fixed-focus lens. By ensuring that the fixed-focus lens satisfies this conditional equation and controlling the ratio of the effective focal length of the third lens element to the effective focal length of the fixed-focus lens, it is beneficial to correct field curvature and other aberrations of the optical system while also raising the optical system's light rays to achieve a higher image plane height, meeting the requirement for a large target surface. Preferably, the fixed-focus lens can further satisfy the following equation: 2.60 ≤ F3 / F ≤ 4.58, further contributing to meeting the requirement for a large target surface.

[0053] In an exemplary embodiment, the fixed-focus lens can satisfy the following condition: -10.70 ≤ F5 / F ≤ 1.69, where F5 is the effective focal length of the fifth lens element, and F is the effective focal length of the fixed-focus lens. By ensuring that the fixed-focus lens satisfies this conditional equation and controlling the ratio of the effective focal length of the fifth lens element to the effective focal length of the fixed-focus lens, the light path can be smoothed, thereby reducing optical system aberrations and improving lens resolution. This also raises the optical system light to achieve a higher image plane height, meeting the requirement for a large target surface. Preferably, the fixed-focus lens can further satisfy the following condition: -9.73 ≤ F5 / F ≤ 1.54, further improving lens resolution and meeting the requirement for a large target surface.

[0054] In an exemplary embodiment, the fixed-focus lens can satisfy: -15.62≤(R41+R42) / F4≤-0.08, wherein R41 is the radius of curvature of the object side of the fourth lens, R42 is the radius of curvature of the image side of the fourth lens, and F4 is the effective focal length of the fourth lens. By making the fixed-focus lens satisfy the above conditional formula and controlling the ratio range of the sum of the radii of curvature of the object side and the image side of the fourth lens to the effective focal length of the fourth lens, it is helpful to converge light from different fields of view, effectively ensure the maximum amount of light passing, and help improve the imaging brightness at the rear of the optical system. At the same time, it is helpful to reduce the generation of aberrations and balance the spherical aberration, which is beneficial to improve the imaging quality. Preferably, the fixed-focus lens can further satisfy: -14.20≤(R41+R42) / F4≤-0.09, which is more conducive to improving the imaging brightness at the rear of the optical system and improving the imaging quality.

[0055] In an exemplary embodiment, a fixed-focus lens can satisfy the following condition: 0.58 ≤ R22 / F2 ≤ 7.32, where R22 is the radius of curvature of the image-side surface of the second lens element, and F2 is the effective focal length of the second lens element. By ensuring that the fixed-focus lens satisfies this conditional equation and controlling the ratio of the radius of curvature of the image-side surface of the second lens element to its effective focal length, the light path can be smoothed, thereby reducing optical system aberrations and improving lens resolution. This also raises the light beam in the optical system to achieve a higher image plane height, meeting the requirement for a large target surface. Preferably, the fixed-focus lens can further satisfy the following condition: 0.64 ≤ R22 / F2 ≤ 6.66, further improving lens resolution and meeting the requirement for a large target surface.

[0056] In an exemplary embodiment, a fixed-focus lens can satisfy the following condition: 0.22 ≤ R32 / F3 ≤ 0.61, where R32 is the radius of curvature of the image-side surface of the third lens element, and F3 is the effective focal length of the third lens element. By ensuring that the fixed-focus lens satisfies this conditional equation and controlling the ratio of the radius of curvature of the image-side surface of the third lens element to the effective focal length of the third lens element, the light path can be smoothed, thereby reducing optical system aberrations and facilitating improved lens resolution. This also raises the optical system light to achieve a higher image plane height, meeting the requirement for a large target surface. Preferably, the fixed-focus lens can further satisfy the following condition: 0.25 ≤ R32 / F3 ≤ 0.58, further facilitating improved lens resolution and meeting the requirement for a large target surface.

[0057] In an exemplary embodiment, the fixed focus lens can meet the following requirements: 0.23mm -1 ≤(V1-V2) / F12≤0.95mm -1 , where V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, and F12 is the combined effective focal length of the first and second lenses. By making the fixed-focus lens meet the above conditional formula and controlling the ratio range of the difference between the Abbe numbers of the first and second lenses and the combined effective focal length of the first and second lenses, the chromatic aberration of the optical system can be effectively balanced, which is conducive to the lens meeting the requirements of large aperture and high resolution. Preferably, the fixed-focus lens can further meet the following requirements: 0.25mm -1 ≤(V1-V2) / F12≤0.86mm -1 , which is more conducive to the lens taking into account both large aperture and high resolution requirements.

[0058] In an exemplary embodiment, the fixed focus lens may satisfy: 0mm -1 ≤(Nd2-Nd1) / F12≤0.005mm -1, where Nd1 is the refractive index of the first lens, Nd2 is the refractive index of the second lens, and F12 is the combined effective focal length of the first lens and the second lens. By making the fixed-focus lens meet the above conditional formula and controlling the ratio range of the difference between the refractive index of the second lens and the first lens and the combined effective focal length of the first lens and the second lens, it is possible to effectively offset the aberration generated between the two lenses and improve the imaging quality of the lens, and also effectively correct the chromatic aberration of the optical system, which is conducive to the lens achieving infrared confocal requirements. Preferably, the fixed-focus lens can further meet: 0mm -1 ≤(Nd2-Nd1) / F12≤0.003mm -1 , which is more conducive to improving the imaging quality of the lens and achieving the infrared confocal requirements of the lens.

[0059] In an exemplary embodiment, a fixed-focus lens can satisfy the following conditions: 0.92mm ≤ F3 / V3 ≤ 1.54mm, where F3 is the effective focal length of the third lens element, and V3 is the Abbe number of the third lens element. By ensuring that the fixed-focus lens meets this conditional equation and controlling the range of the ratio of the effective focal length of the third lens element to the Abbe number of the third lens element, chromatic aberration of the optical system can be effectively reduced, thereby facilitating the lens's ability to achieve both large aperture and high resolution. Preferably, the fixed-focus lens can further satisfy the following conditions: 1.02mm ≤ F3 / V3 ≤ 1.40mm, further facilitating the lens's ability to achieve both large aperture and high resolution.

[0060] In an exemplary embodiment, a fixed-focus lens can satisfy the following conditions: 0.36 ≤ F12 / F3 ≤ 1.05, where F12 is the combined effective focal length of the first and second lenses, and F3 is the effective focal length of the third lens. By ensuring that the fixed-focus lens meets this conditional equation and controlling the ratio of the combined effective focal length of the first and second lenses to the effective focal length of the third lens, various aberrations caused by light passing through the aperture can be effectively balanced, helping the lens achieve both large aperture and high resolution. Preferably, the fixed-focus lens can further satisfy the following conditions: 0.40 ≤ F12 / F3 ≤ 0.96, further facilitating the lens's ability to achieve both large aperture and high resolution.

[0061] In an exemplary embodiment, a fixed-focus lens can satisfy the following equation: 0.79 ≤ F1 / F ≤ 1.74, where F1 is the effective focal length of the first lens element and F is the effective focal length of the fixed-focus lens. By ensuring that the fixed-focus lens satisfies this conditional equation and controlling the ratio of the effective focal length of the first lens element to the effective focal length of the fixed-focus lens element, light entering the optical system is converged, thereby reducing the maximum effective aperture of the first lens element and facilitating lens miniaturization. Preferably, the fixed-focus lens can further satisfy the following equation: 0.88 ≤ F1 / F ≤ 1.58, further facilitating lens miniaturization.

[0062] In an exemplary embodiment, a fixed-focus lens can satisfy the following equation: 1.26 ≤ TTL / F ≤ 1.59, where TTL is the total optical length of the fixed-focus lens and F is the effective focal length of the fixed-focus lens. By ensuring that the fixed-focus lens satisfies this conditional equation, the ratio of the total optical length to the effective focal length of the fixed-focus lens can be controlled, thereby facilitating lens miniaturization. Preferably, the fixed-focus lens can further satisfy the following equation: 1.40 ≤ TTL / F ≤ 1.44, further facilitating lens miniaturization.

[0063] In an exemplary embodiment, a fixed-focus lens can satisfy the following equation: 0.13 ≤ BFL / TTL ≤ 0.20, where BFL is the optical back focus of the fixed-focus lens and TTL is the total optical length of the fixed-focus lens. By ensuring that the fixed-focus lens satisfies this conditional equation and controlling the range of the ratio of the optical back focus to the total optical length of the fixed-focus lens, the lens achieves a longer optical back focus while achieving miniaturization. This helps reserve space for optical component installation, facilitates optical lens assembly, avoids interference, and improves production yield. Preferably, the fixed-focus lens can further satisfy the following equation: 0.14 ≤ BFL / TTL ≤ 0.18, further improving production yield.

[0064] In an exemplary embodiment, a fixed-focus lens can satisfy the following equation: -0.34 ≤ F12 / (F3 + F4) ≤ 2.53, where F12 is the combined effective focal length of the first and second lenses, F3 is the effective focal length of the third lens, and F4 is the effective focal length of the fourth lens. By ensuring that the fixed-focus lens satisfies this conditional equation and controlling the ratio of the combined effective focal length of the first and second lenses to the sum of the effective focal lengths of the third and fourth lenses, the trajectory of light can be effectively controlled, while also reducing the overall aperture of the optical system, facilitating the longitudinal miniaturization of the lens. Preferably, the fixed-focus lens can further satisfy the following equation: -0.31 ≤ F12 / (F3 + F4) ≤ 2.30, further facilitating the longitudinal miniaturization of the lens.

[0065] In an exemplary embodiment, a fixed-focus lens can satisfy the following equation: 0.45 ≤ D1 / TTL ≤ 0.58, where D1 is the maximum effective aperture of the first lens element, and TTL is the total optical length of the fixed-focus lens. By ensuring that the fixed-focus lens satisfies this conditional equation, the ratio of the maximum effective aperture of the first lens element to the total optical length of the fixed-focus lens can be controlled, thereby facilitating lens miniaturization. Preferably, the fixed-focus lens can further satisfy the following equation: 0.50 ≤ D1 / TTL ≤ 0.52, further facilitating lens miniaturization.

[0066] In an exemplary embodiment, a fixed-focus lens can satisfy the following equation: 1.14 ≤ TTL / H ≤ 1.42, where TTL is the total optical length of the fixed-focus lens and H is the full image height of the fixed-focus lens. By ensuring that the fixed-focus lens satisfies this conditional equation, the ratio range of the total optical length to the full image height of the fixed-focus lens can be controlled, thereby facilitating the lens's compactness while achieving a large image area. Preferably, the fixed-focus lens can further satisfy the following equation: 1.27 ≤ TTL / H ≤ 1.29, further facilitating the lens's compactness while achieving a large image area.

[0067] In an exemplary embodiment, the fixed-focus lens may satisfy the following: -0.09≤F5 / (F4+F7+F8+F9)≤0.84, where F4 is the effective focal length of the fourth lens, F5 is the effective focal length of the fifth lens, F7 is the effective focal length of the seventh lens, F8 is the effective focal length of the eighth lens, and F9 is the effective focal length of the ninth lens. By making the fixed-focus lens satisfy the above conditional formula and controlling the ratio range of the effective focal length of the fifth lens to the sum of the effective focal lengths of the fourth lens, the seventh lens, the eighth lens, and the ninth lens, the change in focal length of the lens at different temperatures can be effectively reduced, which is conducive to achieving the athermalization requirement of the lens. Preferably, the fixed-focus lens may further satisfy the following: -0.08≤F5 / (F4+F7+F8+F9)≤0.77, which is more conducive to achieving the athermalization requirement of the lens.

[0068] In an exemplary embodiment, the fixed focus lens may satisfy: -0.25mm -1 ≤V6 / F6≤2.79mm -1 , where V6 is the Abbe number of the sixth lens and F6 is the effective focal length of the sixth lens. By making the fixed-focus lens meet the above conditional formula and controlling the ratio range of the Abbe number of the sixth lens to the effective focal length of the sixth lens, the chromatic aberration of the optical system can be effectively reduced, which is conducive to the lens meeting the requirements of large aperture and high resolution. Preferably, the fixed-focus lens can further meet the following requirements: -0.23mm -1 ≤V6 / F6≤2.54mm -1 , which is more conducive to the lens taking into account both large aperture and high resolution requirements.

[0069] In an exemplary embodiment, a fixed-focus lens can satisfy the following conditions: -0.41 ≤ F5 / F6 ≤ 0.80, where F5 is the effective focal length of the fifth lens element and F6 is the effective focal length of the sixth lens element. By ensuring that the fixed-focus lens satisfies this conditional equation and controlling the ratio of the effective focal length of the fifth lens element to the effective focal length of the sixth lens element, the lens' focal length variation at different temperatures can be effectively reduced, facilitating athermalization. Preferably, the fixed-focus lens can further satisfy the following conditions: -0.37 ≤ F5 / F6 ≤ 0.73, further facilitating athermalization.

[0070] The fixed-focus lens according to the above-mentioned embodiment of the present application adopts nine lenses. By reasonably allocating the optical parameters such as the optical power and surface shape of each lens, it can achieve at least one beneficial effect such as ultra-large aperture (Fno≤1.4), high resolution, small size (TTL≤36mm), infrared confocal (the defocus of infrared light 850nm and visible light 436nm-656nm in the center field of view is ≤20um) and high and low temperature resistance (-20℃~+70℃ and +20℃ at the visible light wavelength of 436nm-656nm, the defocus of the center field of view is ≤9um), large target surface (H≤28mm), and wide operating band (435nm-950nm).

[0071] 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.

[0072] Specific embodiments of fixed-focus lenses applicable to the above-mentioned embodiments will be further described below with reference to the accompanying drawings.

[0073] Example 1

[0074] The following reference Figure 1 A fixed-focus lens according to Example 1 of the present application is described.

[0075] 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 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. A stop STO is provided on the object-side surface S1 of the first lens L1. The first lens L1 and the second lens L2 form a cemented doublet.

[0076] The first lens L1 has positive refractive power, and its object-side surface S1 (STO) is convex, and its image-side surface S2 is convex.

[0077] The second lens L2 has negative refractive power, its object-side surface S2 is concave, and its image-side surface S3 is convex.

[0078] The third lens L3 has positive refractive power, its object-side surface S4 is convex, and its image-side surface S5 is concave.

[0079] The fourth lens L4 has negative refractive power, its object-side surface S6 is convex, and its image-side surface S7 is concave.

[0080] The fifth lens L5 has positive refractive power, and its object-side surface S8 and image-side surface S9 are convex.

[0081] The sixth lens L6 has positive refractive power, and its object-side surface S10 and image-side surface S11 are convex.

[0082] The seventh lens L7 has negative refractive power, its object-side surface S12 is concave, and its image-side surface S13 is convex.

[0083] The eighth lens L8 has negative refractive power, its object-side surface S14 is concave, and its image-side surface S15 is convex.

[0084] The ninth lens L9 has negative refractive power, and its object-side surface S16 and image-side surface S17 are concave.

[0085] The fixed-focus lens further includes a filter / protective glass CG disposed on the image side of the ninth lens L9 , which has an object-side surface S18 and an image-side surface S19 .

[0086] Light from the object passes through the surfaces S1 - S19 in sequence and is finally imaged on the imaging surface IMAGE.

[0087] 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).

[0088] Table 1

[0089]

[0090] In Example 1, the object-side surface and the image-side surface of the third lens element, the fourth lens element, the fifth lens element, the sixth lens element, the seventh lens element, the eighth lens element, and the ninth lens element are all aspherical surfaces. The surface shape of the aspherical lens can be defined by, but is not limited to, the following aspherical surface formula:

[0091]

[0092] 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 below lists the conic coefficient k and the higher-order coefficients A4, A6, A8, A10, A12, A14, and A16 that can be used for each aspheric surface S4 to S17 in Example 1.

[0093] Table 2

[0094] Face number k A4 A6 A8 A10 A12 A14 A16 S4 0.000 1.34E-04 -4.67E-06 -6.58E-09 6.46E-10 -1.74E-11 2.32E-13 -1.04E-15 S5 0.000 2.98E-04 -1.13E-05 1.53E-07 -1.64E-09 5.06E-12 1.09E-13 -8.00E-16 S6 0.000 -4.88E-04 3.70E-06 -8.71E-08 3.32E-09 -7.33E-11 7.35E-13 -2.93E-15 S7 -3.026 -3.46E-05 2.52E-06 -1.96E-09 -2.58E-11 1.23E-11 -3.50E-13 2.13E-15 S8 0.000 -2.46E-05 2.46E-06 9.18E-08 -1.57E-09 -1.59E-11 6.79E-13 -5.36E-15 S9 0.000 7.52E-05 6.90E-06 -4.53E-08 -1.57E-09 1.47E-11 2.72E-13 -2.89E-15 S10 0.000 -1.68E-04 4.70E-06 -1.16E-07 8.15E-10 8.73E-12 -1.25E-13 1.33E-15 S11 0.000 3.86E-05 -4.24E-06 -6.61E-08 2.71E-09 -8.73E-12 -5.99E-13 6.50E-15 S12 -1.372 1.28E-03 -2.43E-05 2.34E-07 -2.96E-10 -2.24E-11 -8.09E-14 1.36E-15 S13 0.217 9.43E-04 -1.85E-05 2.53E-07 -3.51E-09 1.06E-11 3.51E-13 -2.87E-15 S14 0.000 -3.34E-04 4.37E-06 -2.12E-07 4.73E-09 -9.67E-11 1.62E-12 -1.06E-14 S15 0.000 -1.46E-04 5.27E-06 -6.23E-08 2.43E-10 4.05E-12 -3.32E-14 -1.12E-16 S16 0.000 -5.67E-04 -9.91E-07 7.86E-08 -9.19E-10 0.00E+00 0.00E+00 0.00E+00 S17 0.000 -5.91E-04 4.13E-06 -2.23E-08 3.07E-11 0.00E+00 0.00E+00 0.00E+00

[0095] Example 2

[0096] The following reference Figure 2 A fixed-focus lens according to Example 2 of the present application is described.

[0097] like Figure 2As shown, the fixed-focus lens includes, in order from the object side to the image side along the optical axis, 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. A stop STO is provided on the object-side surface S1 of the first lens L1. The first lens L1 and the second lens L2 form a cemented doublet.

[0098] The first lens L1 has positive refractive power, and its object-side surface S1 (STO) is convex, and its image-side surface S2 is convex.

[0099] The second lens L2 has negative refractive power, its object-side surface S2 is concave, and its image-side surface S3 is convex.

[0100] The third lens L3 has positive refractive power, its object-side surface S4 is convex, and its image-side surface S5 is concave.

[0101] The fourth lens L4 has negative refractive power, its object-side surface S6 is convex, and its image-side surface S7 is concave.

[0102] The fifth lens L5 has positive refractive power, and its object-side surface S8 and image-side surface S9 are convex.

[0103] The sixth lens L6 has positive refractive power, and its object-side surface S10 and image-side surface S11 are convex.

[0104] The seventh lens L7 has negative refractive power, its object-side surface S12 is concave, and its image-side surface S13 is convex.

[0105] The eighth lens L8 has negative refractive power, its object-side surface S14 is concave, and its image-side surface S15 is convex.

[0106] The ninth lens L9 has negative refractive power, and its object-side surface S16 is convex, and its image-side surface S17 is concave.

[0107] The fixed-focus lens further includes a filter / protective glass CG disposed on the image side of the ninth lens L9 , which has an object-side surface S18 and an image-side surface S19 .

[0108] Light from the object passes through the surfaces S1 - S19 in sequence and is finally imaged on the imaging surface IMAGE.

[0109] 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).

[0110] Table 3

[0111]

[0112] In Example 2, the object-side surface and the image-side surface of the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are all aspherical surfaces. The surface shape of the aspherical lens can be defined by, but is not limited to, the formula (1) given in Example 1 above.

[0113] Table 4 below gives the conic coefficient k and the higher-order coefficients A4, A6, A8, A10, A12, A14 and A16 that can be used for each aspheric surface S4 to S17 in Example 2.

[0114] Table 4

[0115]

[0116]

[0117] Example 3

[0118] The following reference Figure 3 A fixed-focus lens according to Example 3 of the present application is described.

[0119] 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 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. A stop STO is provided on the object-side surface S1 of the first lens L1. The first lens L1 and the second lens L2 form a cemented doublet.

[0120] The first lens L1 has positive refractive power, and its object-side surface S1 (STO) is convex, and its image-side surface S2 is convex.

[0121] The second lens L2 has negative refractive power, its object-side surface S2 is concave, and its image-side surface S3 is convex.

[0122] The third lens L3 has positive refractive power, its object-side surface S4 is convex, and its image-side surface S5 is concave.

[0123] The fourth lens L4 has negative refractive power, its object-side surface S6 is convex, and its image-side surface S7 is concave.

[0124] The fifth lens L5 has positive refractive power, and its object-side surface S8 and image-side surface S9 are convex.

[0125] The sixth lens L6 has positive refractive power, and its object-side surface S10 and image-side surface S11 are convex.

[0126] The seventh lens L7 has negative refractive power, its object-side surface S12 is concave, and its image-side surface S13 is convex.

[0127] The eighth lens L8 has negative refractive power, and its object-side surface S14 is convex, and its image-side surface S15 is concave.

[0128] The ninth lens L9 has negative refractive power, and its object-side surface S16 is convex, and its image-side surface S17 is concave.

[0129] The fixed-focus lens further includes a filter / protective glass CG disposed on the image side of the ninth lens L9 , which has an object-side surface S18 and an image-side surface S19 .

[0130] Light from the object passes through the surfaces S1 - S19 in sequence and is finally imaged on the imaging surface IMAGE.

[0131] 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).

[0132] Table 5

[0133]

[0134]

[0135] In Example 3, the object-side surface and the image-side surface of the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are all aspherical surfaces. The surface shape of the aspherical lens can be defined by, but is not limited to, the formula (1) given in Example 1 above.

[0136] Table 6 below gives the conic coefficient k and the higher-order coefficients A4, A6, A8, A10, A12, A14 and A16 that can be used for each aspheric surface S4 to S17 in Example 3.

[0137] Table 6

[0138] Face number k A4 A6 A8 A10 A12 A14 A16 S4 0.000 9.95E-05 -3.40E-06 -5.75E-09 6.50E-10 -1.77E-11 2.21E-13 -9.53E-16 S5 0.000 2.79E-04 -1.01E-05 1.48E-07 -1.75E-09 5.52E-12 1.30E-13 -1.00E-15 S6 0.000 -4.78E-04 3.23E-06 -9.47E-08 3.32E-09 -7.21E-11 7.46E-13 -3.26E-15 S7 -2.711 3.01E-05 1.58E-06 -2.26E-09 1.40E-10 1.21E-11 -3.74E-13 2.53E-15 S8 0.000 -1.59E-04 3.11E-06 6.70E-08 -1.86E-09 -1.27E-11 7.35E-13 -6.84E-15 S9 0.000 -1.77E-04 9.17E-06 -5.06E-08 -1.99E-09 9.36E-12 2.47E-13 -2.36E-15 S10 0.000 -5.45E-07 2.20E-06 -8.73E-08 1.09E-09 5.43E-12 -1.99E-13 1.64E-15 S11 0.000 2.61E-04 -6.92E-06 -7.44E-08 3.73E-09 -3.94E-12 -8.17E-13 7.52E-15 S12 -0.723 1.26E-03 -1.95E-05 2.27E-07 -1.13E-09 -1.74E-11 2.20E-13 -1.17E-15 S13 0.048 8.97E-04 -1.45E-05 2.76E-07 -3.82E-09 1.96E-12 3.24E-13 -1.72E-15 S14 0.000 -6.83E-04 4.43E-06 -1.68E-07 4.16E-09 -1.07E-10 1.52E-12 -7.75E-15 S15 0.000 -8.84E-04 1.27E-05 -2.08E-07 1.12E-09 2.30E-11 -2.96E-13 8.97E-16 S16 0.000 -7.41E-04 1.24E-06 3.04E-08 -5.34E-11 0.00E+00 0.00E+00 0.00E+00 S17 0.000 -6.22E-04 2.70E-06 -1.36E-09 -4.56E-11 0.00E+00 0.00E+00 0.00E+00

[0139] Example 4

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

[0141] 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 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. A stop STO is provided on the object-side surface S1 of the first lens L1. The first lens L1 and the second lens L2 form a cemented doublet.

[0142] The first lens L1 has positive refractive power, and its object-side surface S1 (STO) is convex, and its image-side surface S2 is convex.

[0143] The second lens L2 has negative refractive power, its object-side surface S2 is concave, and its image-side surface S3 is convex.

[0144] The third lens L3 has positive refractive power, its object-side surface S4 is convex, and its image-side surface S5 is concave.

[0145] The fourth lens L4 has negative refractive power, its object-side surface S6 is convex, and its image-side surface S7 is concave.

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

[0147] The sixth lens L6 has negative refractive power, and its object-side surface S10 is concave, and its image-side surface S11 is convex.

[0148] The seventh lens L7 has positive refractive power, its object-side surface S12 is convex, and its image-side surface S13 is concave.

[0149] The eighth lens L8 has positive refractive power, its object-side surface S14 is concave, and its image-side surface S15 is convex.

[0150] The ninth lens L9 has negative refractive power, and its object-side surface S16 is convex, and its image-side surface S17 is concave.

[0151] The fixed-focus lens further includes a filter / protective glass CG disposed on the image side of the ninth lens L9 , which has an object-side surface S18 and an image-side surface S19 .

[0152] Light from the object passes through the surfaces S1 - S19 in sequence and is finally imaged on the imaging surface IMAGE.

[0153] 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).

[0154] Table 7

[0155]

[0156] In Example 4, the object-side surface and the image-side surface of the third lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are all aspherical surfaces. The surface shape of the aspherical lens can be defined by, but is not limited to, the formula (1) given in Example 1 above.

[0157] Table 8 below gives the conic coefficient k and the higher-order coefficients A4, A6, A8, A10, A12, A14 and A16 that can be used for each aspheric surface S4 to S5, S8 to S17 in Example 4.

[0158] Table 8

[0159] Face number k A4 A6 A8 A10 A12 A14 A16 S4 0.000 -2.14E-04 -5.75E-07 -2.18E-08 -2.55E-10 1.08E-11 -6.25E-14 0.00E+00 S5 0.000 -5.12E-04 6.73E-06 -1.39E-07 2.13E-09 -1.42E-11 3.24E-14 0.00E+00 S8 0.000 -4.44E-04 5.38E-06 2.32E-08 -2.89E-09 5.00E-11 -2.81E-13 0.00E+00 S9 0.000 -7.48E-04 1.26E-05 -1.92E-07 1.57E-09 4.53E-12 -1.01E-13 0.00E+00 S10 0.000 7.79E-04 -1.24E-05 2.33E-07 -1.81E-09 8.34E-12 -5.45E-14 0.00E+00 S11 0.000 4.55E-04 -2.34E-06 -5.47E-08 4.97E-09 -4.10E-11 -5.93E-14 0.00E+00 S12 -22.306 -3.13E-04 -2.49E-05 8.26E-07 -5.24E-09 -3.71E-11 4.59E-13 0.00E+00 S13 3.162 -3.78E-04 -1.76E-05 3.35E-07 1.04E-09 -8.01E-11 5.52E-13 0.00E+00 S14 0.000 5.75E-04 -7.50E-06 -4.78E-07 1.60E-08 -2.77E-10 1.75E-12 0.00E+00 S15 3.437 8.61E-05 1.38E-05 -4.66E-07 5.84E-09 -7.07E-11 5.87E-13 0.00E+00 S16 -71.785 -1.15E-03 -1.40E-06 3.81E-07 -7.75E-09 4.54E-11 0.00E+00 0.00E+00 S17 -6.202 -7.36E-04 1.08E-05 -1.15E-07 6.69E-10 -1.72E-12 0.00E+00 0.00E+00

[0160] Example 5

[0161] The following reference Figure 5 A fixed-focus lens according to Example 5 of the present application is described.

[0162] 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 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. A stop STO is provided on the object-side surface S1 of the first lens L1. The first lens L1 and the second lens L2 form a cemented doublet.

[0163] The first lens L1 has positive refractive power, and its object-side surface S1 (STO) is convex, and its image-side surface S2 is convex.

[0164] The second lens L2 has negative refractive power, its object-side surface S2 is concave, and its image-side surface S3 is convex.

[0165] The third lens L3 has positive refractive power, its object-side surface S4 is convex, and its image-side surface S5 is concave.

[0166] The fourth lens L4 has negative refractive power, its object-side surface S6 is convex, and its image-side surface S7 is concave.

[0167] The fifth lens L5 has positive refractive power, its object-side surface S8 is convex, and its image-side surface S9 is concave.

[0168] The sixth lens L6 has negative refractive power, and its object-side surface S10 is concave, and its image-side surface S11 is convex.

[0169] The seventh lens L7 has positive refractive power, its object-side surface S12 is convex, and its image-side surface S13 is concave.

[0170] The eighth lens L8 has positive refractive power, its object-side surface S14 is concave, and its image-side surface S15 is convex.

[0171] The ninth lens L9 has negative refractive power, and its object-side surface S16 is convex, and its image-side surface S17 is concave.

[0172] The fixed-focus lens further includes a filter / protective glass CG disposed on the image side of the ninth lens L9 , which has an object-side surface S18 and an image-side surface S19 .

[0173] Light from the object passes through the surfaces S1 - S19 in sequence and is finally imaged on the imaging surface IMAGE.

[0174] 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).

[0175] Table 9

[0176]

[0177] In Example 5, the object-side surface and the image-side surface of the third lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are all aspherical surfaces. The surface shape of the aspherical lens can be defined by, but is not limited to, the formula (1) given in Example 1 above.

[0178] Table 10 below gives the conic coefficient k and the higher-order coefficients A4, A6, A8, A10, A12, A14 and A16 that can be used for each aspheric surface S4 to S5, S8 to S17 in Example 5.

[0179] Table 10

[0180]

[0181]

[0182] Example 6

[0183] The following reference Figure 6 A fixed-focus lens according to Example 6 of the present application is described.

[0184] like Figure 6 As shown, the fixed-focus lens includes, in order from the object side to the image side along the optical axis, 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. A stop STO is provided on the object-side surface S1 of the first lens L1. The first lens L1 and the second lens L2 form a cemented doublet.

[0185] The first lens L1 has positive refractive power, and its object-side surface S1 (STO) is convex, and its image-side surface S2 is convex.

[0186] The second lens L2 has negative refractive power, its object-side surface S2 is concave, and its image-side surface S3 is convex.

[0187] The third lens L3 has positive refractive power, its object-side surface S4 is convex, and its image-side surface S5 is concave.

[0188] The fourth lens L4 has negative refractive power, its object-side surface S6 is convex, and its image-side surface S7 is concave.

[0189] The fifth lens L5 has negative refractive power, its object-side surface S8 is convex, and its image-side surface S9 is concave.

[0190] The sixth lens L6 has positive refractive power, and its object-side surface S10 and image-side surface S11 are convex.

[0191] The seventh lens L7 has negative refractive power, its object-side surface S12 is concave, and its image-side surface S13 is convex.

[0192] The eighth lens L8 has negative refractive power, its object-side surface S14 is concave, and its image-side surface S15 is convex.

[0193] The ninth lens L9 has negative refractive power, and its object-side surface S16 is convex, and its image-side surface S17 is concave.

[0194] The fixed-focus lens further includes a filter / protective glass CG disposed on the image side of the ninth lens L9 , which has an object-side surface S18 and an image-side surface S19 .

[0195] Light from the object passes through the surfaces S1 - S19 in sequence and is finally imaged on the imaging surface IMAGE.

[0196] 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).

[0197] Table 11

[0198]

[0199]

[0200] In Example 6, the object-side surface and the image-side surface of the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are all aspherical surfaces. The surface shape of the aspherical lens can be defined by, but is not limited to, the formula (1) given in Example 1 above.

[0201] Table 12 below gives the conic coefficient k and the higher-order coefficients A4, A6, A8, A10, A12, A14 and A16 that can be used for each aspheric surface S4 to S17 in Example 6.

[0202] Table 12

[0203] Face number k A4 A6 A8 A10 A12 A14 A16 S4 2.935 2.70E-06 -1.14E-06 -4.57E-09 -1.71E-11 1.06E-13 4.90E-15 0.00E+00 S5 0.860 -7.47E-07 -1.79E-06 -4.85E-09 8.60E-11 1.15E-12 -4.37E-15 0.00E+00 S6 0.232 -4.88E-04 -1.85E-07 -1.10E-08 2.36E-10 -3.43E-12 2.15E-14 -2.14E-17 S7 0.196 -7.79E-04 -1.12E-06 1.49E-08 5.25E-10 -8.91E-12 4.03E-14 -4.72E-17 S8 -10.575 -1.72E-04 -1.78E-06 2.05E-08 7.49E-10 -4.73E-12 -1.54E-14 0.00E+00 S9 -20.652 -2.10E-04 4.43E-06 -3.33E-09 -3.10E-10 7.61E-12 -3.23E-14 0.00E+00 S10 -2.805 -3.56E-04 4.07E-06 -1.26E-09 -4.43E-10 1.39E-11 -1.95E-13 -2.76E-16 S11 -4.922 -9.97E-05 -6.19E-07 8.74E-10 -6.71E-11 -3.10E-12 -6.41E-15 1.05E-16 S12 -0.862 1.31E-04 7.54E-07 -5.96E-08 3.15E-11 1.60E-11 -1.22E-13 -2.37E-16 S13 -2.000 1.50E-04 3.99E-06 1.01E-09 3.33E-10 6.80E-12 -1.22E-13 -2.09E-16 S14 -6.517 1.90E-04 1.47E-06 6.98E-08 -2.99E-10 -1.29E-11 8.77E-14 -1.17E-16 S15 -13.603 -2.13E-05 3.45E-06 -1.13E-08 -1.53E-10 4.30E-12 -2.32E-14 -6.67E-17 S16 -0.227 -1.58E-03 6.31E-06 3.92E-08 -6.97E-10 -6.63E-12 1.57E-13 -4.52E-16 S17 -2.735 -6.74E-04 6.89E-06 -3.88E-08 5.44E-11 1.81E-14 2.96E-15 -1.63E-17

[0204] In summary, the conditional expressions in Examples 1 to 6 satisfy the relationships shown in Table 13. In Table 13, the parameters V1, V2, V3, V6, Nd1, and Nd2 have no units, and the units of the remaining parameters are millimeters (mm).

[0205] Table 13

[0206]

[0207]

[0208] 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.

[0209] 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: Along the optical axis from the object side to the image side, they include: a first lens having positive optical power; a second lens having negative optical power; a third lens having positive optical power; a fourth lens element having negative optical power; a fifth lens having positive or negative optical power; a sixth lens having positive or negative optical power; a seventh lens having negative or positive optical power; an eighth lens having negative or positive optical power; a ninth lens element having negative optical power; The fixed-focus lens has nine lenses with optical power; At least one of the fifth lens and the sixth lens has a positive optical power, the sixth lens and the seventh lens have opposite optical powers, and the seventh lens and the eighth lens have the same optical power; The fixed-focus lens satisfies: 0.58≤R22 / F2≤7.33, Wherein, R22 is the curvature radius of the image side surface of the second lens, and F2 is the effective focal length of the second lens.

2. The fixed-focus lens according to claim 1, wherein: The object-side surface of the first lens is convex, and the image-side surface is convex; The object side surface of the second lens is concave, and the image side surface is convex; The object-side surface of the third lens is convex, and the image-side surface is concave; and The object-side surface of the fourth lens is convex, and the image-side surface is concave.

3. The fixed-focus lens according to claim 2, wherein: The object-side surface of the fifth lens is convex, and the image-side surface is convex; the object-side surface of the sixth lens is convex, and the image-side surface is convex; the object-side surface of the seventh lens is concave, and the image-side surface is convex; the object-side surface of the eighth lens is concave, and the image-side surface is convex; and the object-side surface of the ninth lens is concave, and the image-side surface is concave; or The object-side surface of the fifth lens is convex, and the image-side surface is convex; the object-side surface of the sixth lens is convex, and the image-side surface is convex; the object-side surface of the seventh lens is concave, and the image-side surface is convex; the object-side surface of the eighth lens is concave, and the image-side surface is convex; and the object-side surface of the ninth lens is convex, and the image-side surface is concave; or The object-side surface of the fifth lens is convex, and the image-side surface is convex; the object-side surface of the sixth lens is convex, and the image-side surface is convex; the object-side surface of the seventh lens is concave, and the image-side surface is convex; the object-side surface of the eighth lens is convex, and the image-side surface is concave; and the object-side surface of the ninth lens is convex, and the image-side surface is concave; or The object-side surface of the fifth lens is convex, and the image-side surface is concave; the object-side surface of the sixth lens is concave, and the image-side surface is convex; the object-side surface of the seventh lens is convex, and the image-side surface is concave; the object-side surface of the eighth lens is concave, and the image-side surface is convex; and the object-side surface of the ninth lens is convex, and the image-side surface is concave; or The object side surface of the fifth lens is convex, and the image side surface is concave, the object side surface of the sixth lens is convex, and the image side surface is convex, the object side surface of the seventh lens is concave, and the image side surface is convex, the object side surface of the eighth lens is concave, and the image side surface is convex, and the object side surface of the ninth lens is convex, and the image side surface is concave.

4. 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: 0.22≤R32 / F3≤0.61, -15.62≤(R41+R42) / F4≤-0.08, Among them, R32 is the curvature radius of the image side of the third lens, F3 is the effective focal length of the third lens, R41 is the curvature radius of the object side of the fourth lens, R42 is the curvature radius of the image side of the fourth lens, and F4 is the effective focal length of the fourth lens.

5. 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: 0.79≤F1 / F≤1.74, 2.34≤F3 / F≤5.04, 0.36≤F12 / F3≤1.05, -0.34≤F12 / (F3+F4)≤2.53, -10. 70≤F5 / F≤1.69, -0.41≤F5 / F6≤0.80, -5.95≤F9 / F≤-0.98, -0.09≤F5 / (F4+F7+F8+F9)≤0.84, Among them, F1 is the effective focal length of the first lens, F12 is the combined effective focal length of the first lens and the second lens, F3 is the effective focal length of the third lens, F4 is the effective focal length of the fourth lens, F5 is the effective focal length of the fifth lens, F6 is the effective focal length of the sixth lens, F7 is the effective focal length of the seventh lens, F8 is the effective focal length of the eighth lens, F9 is the effective focal length of the ninth lens, and F is the effective focal length of the fixed-focus lens.

6. 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: <h2 style=";text-align:left;direction:ltr">0mm<h2 style=";text-align:left;direction:ltr"> -1 <h2 style=";text-align:left;direction:ltr"> ≤(Nd2-Nd1) / F12≤0.005mm<h2 style=";text-align:left;direction:ltr"> -1 <h2 style=";text-align:left;direction:ltr"> ,0.23mm<h2 style=";text-align:left;direction:ltr"> -1 <h2 style=";text-align:left;direction:ltr"> ≤(V1-V2) / F12≤0.95mm<h2 style=";text-align:left;direction:ltr"> -1 <h2 style=";text-align:left;direction:ltr"> ,0.92mm≤F3 / V3≤1.54mm,-0.25mm<h2 style=";text-align:left;direction:ltr"> -1 <h2 style=";text-align:left;direction:ltr"> ≤V6 / F6≤2.79mm<h2 style=";text-align:left;direction:ltr"> -1 <h2 style=";text-align:left;direction:ltr"> , Wherein, Nd1 is the refractive index of the first lens, Nd2 is the refractive index of the second lens, V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, V3 is the Abbe number of the third lens, V6 is the Abbe number of the sixth lens, F12 is the combined effective focal length of the first lens and the second lens, F3 is the effective focal length of the third lens, and F6 is the effective focal length of the sixth lens.

7. 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: 1.26≤TTL / F≤1.59, 0.13≤BFL / TTL≤0.20, 0.45≤D1 / TTL≤0.58, 1.14≤TTL / H≤1.42, Wherein, TTL is the total optical length of the fixed-focus lens, BFL is the optical back focus of the fixed-focus lens, H is the full image height of the fixed-focus lens, F is the effective focal length of the fixed-focus lens, and D1 is the maximum effective aperture of the first lens.

8. 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: <h2 style=";text-align:left;direction:ltr">0.64≤R22 / F2≤6.66,0.25≤R32 / F3≤0.58,0.88≤F1 / F≤1.58,2 .60≤F3 / F≤4.58,-9.73≤F5 / F≤1.54,-0.37≤F5 / F6≤0.73,0mm<h2 style=";text-align:left;direction:ltr"> -1 <h2 style=";text-align:left;direction:ltr"> ≤(Nd2-Nd1) / F12≤0.003mm<h2 style=";text-align:left;direction:ltr"> -1 <h2 style=";text-align:left;direction:ltr"> ,0.25mm<h2 style=";text-align:left;direction:ltr"> -1 <h2 style=";text-align:left;direction:ltr"> ≤(V1-V2) / F12≤0.86mm<h2 style=";text-align:left;direction:ltr"> -1 <h2 style=";text-align:left;direction:ltr"> ,1.02mm≤F3 / V3≤1.40mm,1.40≤TTL / F≤1.44,0.50≤D1 / TTL≤0.52,1.27≤TTL / H≤1.29, Wherein, R22 is the curvature radius of the image-side surface of the second lens, F2 is the effective focal length of the second lens, R32 is the curvature radius of the image-side surface of the third lens, F3 is the effective focal length of the third lens, F1 is the effective focal length of the first lens, F is the effective focal length of the fixed-focus lens, F5 is the effective focal length of the fifth lens, F6 is the effective focal length of the sixth lens, Nd1 is the refractive index of the first lens, Nd2 is the refractive index of the second lens, F12 is the combined effective focal length of the first lens and the second lens, V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, V3 is the Abbe number of the third lens, TTL is the total optical length of the fixed-focus lens, H is the total image height of the fixed-focus lens, and D1 is the maximum effective aperture of the first lens.

9. 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: -14.20≤(R41+R42) / F4≤-0.09,0.40≤F12 / F3≤0.96,-0.31≤F12 / (F3+F4)≤2.30,-5.41≤F9 / F≤-1.09,-0.08≤F5 / (F4+F7+F8+F9)≤0.77,-0.23mm -1 ≤V6 / F6≤2.54mm -1 ,0.14≤BFL / TTL≤0.18, Among them, R41 is the curvature radius of the object side of the fourth lens, R42 is the curvature radius of the image side of the fourth lens, F4 is the effective focal length of the fourth lens, F12 is the combined effective focal length of the first lens and the second lens, F3 is the effective focal length of the third lens, F5 is the effective focal length of the fifth lens, F7 is the effective focal length of the seventh lens, F8 is the effective focal length of the eighth lens, F9 is the effective focal length of the ninth lens, F is the effective focal length of the fixed-focus lens, V6 is the Abbe number of the sixth lens, F6 is the effective focal length of the sixth lens, TTL is the total optical length of the fixed-focus lens, and BFL is the optical back focus of the fixed-focus lens.

Images