A fixed focus lens

Abstract

This invention discloses a fixed-focus lens. The fixed-focus lens includes, arranged sequentially along the optical axis from object to image, a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, an aperture stop, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, and a ninth lens with negative optical power. The first, third, and seventh lenses are all spherical glass lenses, the sixth lens is a glass aspherical lens, and the second, fourth, fifth, eighth, and ninth lenses are all plastic aspherical lenses. This invention achieves a low-cost fixed-focus lens design that balances imaging requirements and a compact structure. This fixed-focus lens can be matched with a 1 / 2.7″ imaging chip, meeting the requirements of small size, large field of view, and good center-to-edge resolution. Its overall performance meets the requirements for use in general-purpose security monitoring chips.

Description

Technical Field

[0001] This invention relates to the field of lens technology, and more particularly to a fixed-focus lens. Background Technology

[0002] A wide-angle lens is a short focal length lens with a large field of view, capable of capturing a large area of ​​scenery at a relatively short shooting distance. Therefore, wide-angle lenses are widely used in many fields such as security, smart homes, and automotive applications. However, currently popular wide-angle fixed-focus lenses on the market have relatively small apertures, resulting in less light transmission in low-light environments, failing to provide high-resolution surveillance images, while overexposure occurs in high-light conditions. Summary of the Invention

[0003] This invention provides a fixed-focus lens that uses three glass spherical lenses, one glass aspherical lens, and five plastic aspherical lenses. By optimizing the optical power matching and relative positions of each lens element, a low-cost fixed-focus lens design that balances imaging requirements and a compact structure is achieved. This fixed-focus lens can be matched with a 1 / 2.7″ imaging chip, meeting the requirements of small size, large field of view, and good resolution from center to edge. Its overall performance meets the requirements of general-purpose security monitoring chips.

[0004] According to one aspect of the present invention, a fixed-focus lens is provided, comprising a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, an aperture stop, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, and a ninth lens with negative optical power arranged sequentially along the optical axis from the object side to the image side. The first lens, the third lens, and the seventh lens are all glass spherical lenses, the sixth lens is a glass aspherical lens, and the second lens, the fourth lens, the fifth lens, the eighth lens, and the ninth lens are all plastic aspherical lenses.

[0005] The fixed-focus lens satisfies the following condition:

[0006] 1.36≤H / f≤1.38;

[0007] Where f represents the focal length of the fixed-focus lens, and H represents the vertical height of the intersection point of the principal ray of the maximum field of view and the image plane.

[0008] Optionally, along the optical axis from the object side to the image side, the first lens is a convex-concave lens, the second lens is a convex-concave lens, the third lens is a concave-convex lens, the fourth lens is a concave-convex lens, the fifth lens is a convex-concave lens, the sixth lens is a convex-convex lens, the seventh lens is a concave-concave lens, the eighth lens is a convex-convex lens, and the ninth lens is a convex-concave lens.

[0009] Optionally, the third lens, the fifth lens, and the sixth lens satisfy the following condition:

[0010] 1.85≤Nd3≤2.00;

[0011] 23.79≤Vd3≤25.43;

[0012] 1.64≤Nd5≤1.67;

[0013] 19.28≤Vd5≤23.92;

[0014] 1.69≤Nd6≤1.81;

[0015] 40.91≤Vd6≤48.06;

[0016] Wherein, Nd3, Nd5, and Nd6 represent the refractive indices of the third lens, the fifth lens, and the sixth lens, respectively, and Vd3, Vd5, and Vd6 represent the Abbe numbers of the third lens, the fifth lens, and the sixth lens, respectively.

[0017] Optionally, the focal lengths of the first lens and the second lens satisfy the following condition:

[0018] -8.74≤(f1+f2) / f≤-7.06;

[0019] Where f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, and f represents the focal length of the fixed-focus lens.

[0020] Optionally, the lens diameter of the first lens and the total optical length of the fixed-focus lens satisfy the following condition:

[0021] 0.58≤ΦL1 / TTL≤0.71;

[0022] Wherein, ΦL1 represents the lens diameter of the first lens, and TTL represents the total optical length of the fixed-focus lens.

[0023] Optionally, the focal length of the third lens and the focal length of the fourth lens satisfy the following condition:

[0024] 10.57≤(f3+f4) / f≤12.42;

[0025] Where f3 represents the focal length of the third lens, f4 represents the focal length of the fourth lens, and f represents the focal length of the fixed-focus lens.

[0026] Optionally, the focal length of the fifth lens and the focal length of the sixth lens satisfy the following condition:

[0027] 5.1≤(f5+f6) / f≤5.82;

[0028] Where f5 represents the focal length of the fifth lens, f6 represents the focal length of the sixth lens, and f represents the focal length of the fixed-focus lens.

[0029] Optionally, the focal lengths of the seventh lens and the eighth lens satisfy the following condition:

[0030] 2.37≤(f7+f8) / f≤2.74;

[0031] Wherein, f7 represents the focal length of the seventh lens, f8 represents the focal length of the eighth lens, and f represents the focal length of the fixed-focus lens.

[0032] Optionally, the focal length of the ninth lens satisfies the following condition:

[0033] -58.59≤f9 / f≤-16.8;

[0034] Where f9 represents the focal length of the ninth lens, and f represents the focal length of the fixed-focus lens.

[0035] Optionally, the fixed-focus lens satisfies the following condition:

[0036] 1.95≤F≤2.294;

[0037] 0.11≤BFL / TTL≤0.13;

[0038] Wherein, F represents the aperture number of the fixed-focus lens, BFL represents the distance from the vertex of the last optical surface of the fixed-focus lens to the image plane, and TTL represents the total optical length of the fixed-focus lens.

[0039] The fixed-focus lens provided in this invention includes a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, an aperture stop, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, and a ninth lens with negative optical power, arranged sequentially along the optical axis from the object side to the image side. The first, third, and seventh lenses are all spherical glass lenses, the sixth lens is a glass aspherical lens, and the second, fourth, fifth, eighth, and ninth lenses are all plastic aspherical lenses. By using a hybrid combination of 3 spherical glass lenses, 1 aspherical glass lens, and 5 aspherical plastic lenses, aberrations can be effectively corrected, ensuring sufficiently good image quality. This invention offers high image quality at a low cost, and can be paired with 5MP / 4K and 1 / 2.7″ type chips, making it widely applicable. By designing a fixed-focus lens that meets the requirements of 1.36≤H / f≤1.38, and constraining the focal length of the fixed-focus lens and the vertical height of the intersection point of the principal ray of the maximum field of view with the image plane, the field of view of the fixed-focus lens can be controlled within a certain range to meet usage requirements. The technical solution of this invention, through optimizing the optical power matching and relative position of each lens element, ultimately achieves the design of a low-cost fixed-focus lens that balances imaging requirements and a compact structure. This fixed-focus lens can be matched with a 1 / 2.7″ imaging chip, meeting the requirements of small size, large field of view, and good resolution from center to edge. Its overall performance meets the usage requirements of general-purpose security monitoring chips.

[0040] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the structure of a fixed-focus lens provided in an embodiment of the present invention;

[0043] Figure 2 An axial aberration curve of a fixed-focus lens is provided for an embodiment of the present invention;

[0044] Figure 3 A fan pattern of a fixed-focus lens in a 0-degree field of view is provided as an embodiment of the present invention;

[0045] Figure 4A fan pattern of a fixed-focus lens in a 25.80-degree field of view, provided as an embodiment of the present invention;

[0046] Figure 5 A fan pattern of a fixed-focus lens in a 43.00-degree field of view, provided for an embodiment of the present invention;

[0047] Figure 6 A fan pattern of a fixed-focus lens in a 60.20-degree field of view, provided as an embodiment of the present invention;

[0048] Figure 7 A fan pattern of a fixed-focus lens in a 68.80-degree field of view, provided for an embodiment of the present invention;

[0049] Figure 8 A fan pattern of a fixed-focus lens in a 77.40-degree field of view, provided for an embodiment of the present invention;

[0050] Figure 9 A fan pattern of a fixed-focus lens in an 86.00-degree field of view, provided for an embodiment of the present invention;

[0051] Figure 10 A lateral chromatic aberration curve of a fixed-focus lens is provided as an embodiment of the present invention;

[0052] Figure 11 This is a schematic diagram of another fixed-focus lens provided in an embodiment of the present invention;

[0053] Figure 12 An axial aberration curve diagram of another fixed-focus lens provided in an embodiment of the present invention;

[0054] Figure 13 Another fixed-focus lens with a 0-degree field of view provided in this embodiment of the invention;

[0055] Figure 14 Another fixed-focus lens provided in this embodiment of the invention has a fan-shaped optical pattern in a 25.94-degree field of view;

[0056] Figure 15 Another fixed-focus lens provided in this embodiment of the invention has a field of view of 43.64 degrees.

[0057] Figure 16 Another fixed-focus lens provided in this embodiment of the invention has a fan-shaped optical pattern with a field of view of 61.45 degrees.

[0058] Figure 17 Another fixed-focus lens provided in this embodiment of the invention has a fan-shaped optical pattern at a field of view of 69.98 degrees;

[0059] Figure 18 Another fixed-focus lens provided in this embodiment of the invention has a fan-shaped optical pattern with a field of view of 78.25 degrees.

[0060] Figure 19 Another fixed-focus lens provided in this embodiment of the invention has an optical fan pattern at a field of view of 89.71 degrees;

[0061] Figure 20 A lateral chromatic aberration curve of another fixed-focus lens provided in an embodiment of the present invention;

[0062] Figure 21 This is a schematic diagram of the structure of another fixed-focus lens provided in an embodiment of the present invention;

[0063] Figure 22 An axial aberration curve diagram of another fixed-focus lens provided in an embodiment of the present invention;

[0064] Figure 23 This invention provides another fixed-focus lens with a 0-degree field of view.

[0065] Figure 24 A fan-shaped optical pattern of a fixed-focus lens with a field of view of 25.85 degrees, provided for an embodiment of the present invention;

[0066] Figure 25 A fan-shaped optical pattern of a fixed-focus lens with a field of view of 43.30 degrees, provided for an embodiment of the present invention;

[0067] Figure 26 A fan-shaped optical pattern of a fixed-focus lens in a 61.00-degree field of view, provided as an embodiment of the present invention;

[0068] Figure 27 A fan-shaped optical pattern of a fixed-focus lens with a field of view of 69.67 degrees, provided for an embodiment of the present invention;

[0069] Figure 28 A fan-shaped optical pattern of a fixed-focus lens with a field of view of 78.29 degrees, provided for an embodiment of the present invention;

[0070] Figure 29 A fan-shaped optical pattern of a fixed-focus lens with a field of view of 89.49 degrees, provided for an embodiment of the present invention;

[0071] Figure 30 This is a chromatic aberration curve of a fixed-focus lens provided in an embodiment of the present invention. Detailed Implementation

[0072] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0073] It should be noted that the terminology used in the embodiments of this invention is for the purpose of describing specific embodiments only and is not intended to limit the invention. It should be noted that directional terms such as "above," "below," "left," and "right" described in the embodiments of this invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this invention. Furthermore, in the context, it should be understood that when referring to an element being formed "above" or "below" another element, it can be formed not only directly "above" or "below" the other element, but also indirectly "above" or "below" the other element through an intermediate element. The terms "first," "second," etc., are used for descriptive purposes only and do not indicate any order, quantity, or importance, but are only used to distinguish different components. It should be understood that such terms can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0074] Figure 1 This is a schematic diagram of the structure of a fixed-focus lens provided in an embodiment of the present invention, with reference to... Figure 1 The fixed-focus lens provided in this embodiment of the invention includes a first lens 10 with negative optical power, a second lens 20 with negative optical power, a third lens 30 with positive optical power, a fourth lens 40 with positive optical power, an aperture stop 100, a fifth lens 50 with positive optical power, a sixth lens 60 with positive optical power, a seventh lens 70 with negative optical power, an eighth lens 80 with positive optical power, and a ninth lens 90 with negative optical power, arranged sequentially from the object side to the image side along the optical axis. The first lens 10, the third lens 30, and the seventh lens 70 are all glass spherical lenses, the sixth lens 60 is a glass aspherical lens, and the second lens 20, the fourth lens 40, the fifth lens 50, the eighth lens 80, and the ninth lens 90 are all plastic aspherical lenses.

[0075] Fixed-focus lenses satisfy the following condition:

[0076] 1.36≤H / f≤1.38;

[0077] Where f represents the focal length of the fixed-focus lens, and H represents the vertical height of the point where the principal ray of the maximum field of view intersects the image plane.

[0078] It is understandable that optical power, the reciprocal of focal length, characterizes the ability of an optical system to deflect light. The larger the absolute value of optical power, the stronger the ability to bend light; the smaller the absolute value, the weaker the ability to bend light. When optical power is positive, the refraction of light is converging; when optical power is negative, the refraction of light is diverging. In practical implementation, refer to... Figure 1 The fixed-focus lens also includes a flat glass plate 110, which is located on the side closest to the image plane. The flat glass plate 110 protects the photosensitive chip in the imaging sensor, which converts the light signals collected by the fixed-focus lens into electrical signals, thereby ensuring the imaging effect of the fixed-focus lens. The first lens 10, second lens 20, third lens 30, fourth lens 40, aperture 100, fifth lens 50, sixth lens 60, seventh lens 70, eighth lens 80, ninth lens 90, and flat glass plate 110 can be housed in a single lens barrel. Figure 1 (Not shown in the image) The lens employs a hybrid combination of 3 spherical glass lenses, 1 aspherical glass lens, and 5 aspherical plastic lenses. The glass and plastic materials complement each other, effectively balancing the resolution of the fixed-focus lens under high and low temperatures. Furthermore, the appropriate combination of glass lenses effectively corrects lens aberrations, ensuring good image quality at a relatively low cost. It can be paired with 5MP / 4K, 1 / 2.7″ type sensors, making it widely applicable. By designing the fixed-focus lens to meet the requirements of 1.36 ≤ H / f ≤ 1.38, and constraining the focal length and the vertical height of the intersection point of the principal ray of the maximum field of view with the image plane, the field of view of the fixed-focus lens can be controlled within a certain range to meet usage requirements. It should be noted that... Figure 1 The structural diagrams in the following embodiments are for illustrative purposes only, and shapes such as aspherical surfaces are not represented in accordance with actual conditions.

[0079] The technical solution of this invention optimizes the optical power matching and relative position of each lens element, ultimately achieving a low-cost fixed-focus lens design that balances imaging requirements and a compact structure. This fixed-focus lens can be matched with a 1 / 2.7″ imaging chip, meeting the requirements of small size, large field of view, and good resolution from center to edge. Its overall performance meets the requirements of general-purpose security monitoring chips.

[0080] Based on the above embodiments, optionally, along the optical axis from the object side to the image side, the first lens 10 is a convex-concave lens, the second lens 20 is a convex-concave lens, the third lens 30 is a concave-convex lens, the fourth lens 40 is a concave-convex lens, the fifth lens 50 is a convex-concave lens, the sixth lens 60 is a convex-convex lens, the seventh lens 70 is a concave-concave lens, the eighth lens 80 is a convex-convex lens, and the ninth lens 90 is a convex-concave lens.

[0081] By setting the shape of each lens, the optical power of each lens can be adapted.

[0082] Optionally, the third lens 30, the fifth lens 50, and the sixth lens 60 satisfy the following condition:

[0083] 1.85≤Nd3≤2.00;

[0084] 23.79≤Vd3≤25.43;

[0085] 1.64≤Nd5≤1.67;

[0086] 19.28≤Vd5≤23.92;

[0087] 1.69≤Nd6≤1.81;

[0088] 40.91≤Vd6≤48.06;

[0089] Wherein, Nd3, Nd5, and Nd6 represent the refractive indices of the third lens 30, the fifth lens 50, and the sixth lens 60, respectively, and Vd3, Vd5, and Vd6 represent the Abbe numbers of the third lens 30, the fifth lens 50, and the sixth lens 60, respectively.

[0090] The third lens 30, made of high-refractive-index, low-dispersion glass, provides powerful optical power and chromatic aberration correction capabilities, laying the foundation for aberration correction. Its stable physicochemical properties help resist environmental changes. This significantly reduces the size and weight of the fixed-focus lens. Specifically, it allows for the use of lens surfaces with smaller curvature while maintaining the same optical power. Furthermore, the fifth lens 50 and the sixth lens 60 are located behind the aperture stop 100. Introducing an aspherical lens after the aperture stop 100 effectively improves chromatic aberration in light passing through the aperture stop 100, thus significantly improving the edge image quality of the wide-angle lens. Simultaneously, the sixth lens 60, made of glass aspherical lens, combines the excellent thermal stability and dispersion characteristics of glass with the powerful aberration correction capabilities of aspherical surfaces. Positioned as the second lens after the aperture stop 100, the sixth lens 60 can simultaneously correct advanced aberrations and chromatic aberration, making it crucial for ensuring high resolution across the entire field of view.

[0091] Optionally, the focal lengths of the first lens 10 and the second lens 20 satisfy the following condition:

[0092] -8.74≤(f1+f2) / f≤-7.06;

[0093] Where f1 represents the focal length of the first lens 10, f2 represents the focal length of the second lens 20, and f represents the focal length of the fixed-focus lens.

[0094] By rationally setting the ratio between the sum of the focal lengths of the first lens 10 and the second lens 20 and the focal length of the fixed-focus lens, it is helpful to reduce the overall length of the lens. At the same time, it is also beneficial to correct aberrations at ultra-large apertures, ensuring that the fixed-focus lens has high resolving power.

[0095] Optionally, the lens diameter of the first lens 10 and the total optical length of the fixed-focus lens satisfy the following condition:

[0096] 0.58≤ΦL1 / TTL≤0.71;

[0097] Wherein, ΦL1 represents the lens diameter of the first lens 10, and TTL represents the total optical length of the fixed-focus lens.

[0098] By limiting the ratio of the diameter of the first lens 10 to the total optical length (TTL) of the fixed-focus lens, the size of the lens can be effectively controlled, making the lens smaller while maximizing the field of view and light intake to meet the needs of use under more demanding conditions.

[0099] As required, the focal lengths of the third lens 30 and the fourth lens 40 satisfy the following condition:

[0100] 10.57≤(f3+f4) / f≤12.42;

[0101] Where f3 represents the focal length of the third lens 30, f4 represents the focal length of the fourth lens 40, and f represents the focal length of the fixed-focus lens.

[0102] The third lens 30 and the fourth lens 40 play a crucial role in ensuring that light rays can pass through the aperture 100 smoothly and symmetrically, which is of great importance in controlling aberrations.

[0103] Optionally, the focal lengths of the fifth lens 50 and the sixth lens 60 satisfy the following condition:

[0104] 5.1≤(f5+f6) / f≤5.82;

[0105] Where f5 represents the focal length of the fifth lens 50, f6 represents the focal length of the sixth lens 60, and f represents the focal length of the fixed-focus lens.

[0106] When light passes through aperture 100 and enters the fifth lens 50 and the sixth lens 60, the light refraction is relatively gentle, which can effectively reduce the sensitivity of the system and improve the yield. This also makes lens production and assembly easier, and results in more stable and reliable performance during use. Furthermore, the fifth lens 50 and the sixth lens 60 can initially correct the shape of the light beam, smoothly guiding large-angle off-axis rays and preventing severe, uncorrectable aberrations caused by off-axis rays suddenly encountering strong lens elements, thus achieving initial chromatic aberration balance.

[0107] Optionally, the focal lengths of the seventh lens 70 and the eighth lens 80 satisfy the following condition:

[0108] 2.37≤(f7+f8) / f≤2.74;

[0109] Where f7 represents the focal length of the seventh lens 70, f8 represents the focal length of the eighth lens 80, and f represents the focal length of the fixed-focus lens.

[0110] The combination of the seventh lens 70 and the eighth lens 80 can eliminate advanced aberrations and residual spherical aberrations that were not eliminated at the front end.

[0111] Optionally, the focal length of the ninth lens 90 satisfies the following condition:

[0112] -58.59≤f9 / f≤-16.8;

[0113] Where f9 represents the focal length of the ninth lens 90, and f represents the focal length of the fixed-focus lens.

[0114] The ninth lens, 90, is a negative lens, which can keep the angle of the principal ray within a suitable range. It can also adjust the height of the intersection point between the principal ray and the image plane at the end of a fixed-focus lens. It is compatible with various chips and saves lens costs on the other hand.

[0115] Optionally, a fixed-focus lens satisfies the following condition:

[0116] 1.95≤F≤2.294;

[0117] 0.11≤BFL / TTL≤0.13;

[0118] Where F represents the aperture number of the fixed-focus lens, BFL represents the distance from the vertex of the last optical surface of the fixed-focus lens to the image plane, and TTL represents the total optical length of the fixed-focus lens.

[0119] A smaller F-number in an optical system results in stronger light collection, enabling clear images in low-light environments and making it suitable for special conditions such as low-light surveillance. BFL and TTL meet these requirements, effectively controlling lens size and allowing for smaller lenses while maximizing the field of view and light intake to meet the demands of more stringent conditions.

[0120] By rationally allocating parameters such as the material, optical power, center thickness of each lens, and on-axis spacing between each lens, a fixed-focus lens can achieve at least one beneficial effect, such as excellent imaging, compact structure, and low cost.

[0121] In this embodiment of the invention, the aspherical lens of the fixed-focus lens satisfies the following formula:

[0122] ;

[0123] Where Z is the axial distance from the vertex of the surface at a position perpendicular to the optical axis at a height r; c represents the curvature at the vertex of the aspherical surface; k is the fitted conic coefficient; a4, a6, a8, a 10 a 12 a 14 a 16 For the higher-order aspheric coefficients corresponding to the fourth, sixth, eighth, tenth, twelfth, fourteenth, and sixteenth orders of aspheric surfaces, a i r i These can be combined to form higher-order terms for the corresponding aspherical surfaces.

[0124] For example, Table 1 shows the relationship with Figure 1 The specific parameters of the corresponding prime lens are as follows:

[0125] Table 1 Specific parameters of fixed focal length lenses

[0126]

[0127] Table 2 shows the parameter data of each lens in Example 1. The focal length f of the fixed-focus lens in Example 1 is 2.219mm and the aperture number F is 2.238.

[0128] Table 2 Design values ​​of optical physical parameters of the fixed-focus lens in Example 1

[0129]

[0130] The surface number is assigned according to the order of the lenses' surfaces. "STO" indicates the aperture stop of a fixed-focus lens. The radius of curvature indicates the degree of curvature of the corresponding lens surface. A positive value means the surface bends towards the image plane, and a negative value means the surface bends towards the object plane. "Infinite" indicates that the surface is flat and the radius of curvature is infinite. The thickness indicates the central axial distance between the current surface and the next surface. Both the radius of curvature and the thickness are in mm. The material (Nd) indicates the refractive index, which represents the ability of the material between the current surface and the next surface to deflect light. A space indicates that the current position is air and the refractive index is 1. The material (Vd) indicates the Abbe number, which represents the dispersion characteristics of the material between the current surface and the next surface. A space indicates that the current position is air.

[0131] Table 3 shows the design values ​​of the aspherical parameters in Example 1:

[0132]

[0133] Continued from Table 3

[0134]

[0135] Where -8.890899999161E-03 indicates that the a4 coefficient of face number 3 is -8.890899999161×10 -3 .

[0136] Figure 2 The axial aberration curve of a fixed-focus lens provided in this embodiment of the invention is shown. The vertical direction represents the normalized aperture, 0 indicates that it is on the optical axis, and the vertical vertex represents the maximum pupil radius. The horizontal direction represents the offset relative to the image plane, in millimeters (mm). Figure 2 Different linear curves represent different wavelengths of system imaging, by Figure 2 It can be seen that the axial aberrations of the normalized aperture at different wavelengths (0~1.0) are all controlled within the range of (-0.04mm, +0.04mm), indicating that the spherical aberration of this fixed-focus lens is well controlled at all wavelengths, which can meet the requirements of wide-spectrum applications. In addition, at the pupil positions of 0.5~0.9, there is no obvious chromatic aberration between visible light and infrared light, which meets the basic requirement of clear imaging at night and achieves the effect of clear imaging across the entire spectral band.

[0137] Ray fan diagrams are one of the commonly used evaluation methods by optical designers. Figure 3 This invention provides a fan pattern of a fixed-focus lens in a 0-degree field of view, as provided in an embodiment of the invention. Figure 4 This invention provides an optical fan pattern for a fixed-focus lens with a 25.80-degree field of view, as provided in an embodiment of the invention. Figure 5 This invention provides a fixed-focus lens with a field of view of 43.00 degrees. Figure 6 This invention provides a fixed-focus lens with a 60.20-degree field of view, as shown in an embodiment of the invention. Figure 7 This invention provides a fixed-focus lens with a 68.80-degree field of view, as shown in an embodiment of the invention. Figure 8 This invention provides an optical fan pattern for a fixed-focus lens with a 77.40-degree field of view, as provided in an embodiment of the invention. Figure 9 An optical fan pattern of a fixed-focus lens in an 86.00-degree field of view, as provided in an embodiment of the present invention, is shown below. Figures 3-9 As shown, the horizontal axis in the figure represents the normalized beam aperture, and the vertical axis represents the transverse aberration. Ideally, each curve should perfectly coincide with the horizontal axis, at which point all rays in that field of view focus at the same point on the image plane; the vertical axis in a single image can also represent the maximum dispersion range of the beam on the ideal image plane. The fan diagram not only reflects monochromatic aberrations of different wavelengths but also indicates the magnitude of transverse chromatic aberration. Figures 3-9 It can be seen that this fixed-focus lens closely approximates the horizontal axis at all wavelengths across all fields of view, indicating that its transverse aberrations at all wavelengths are well corrected. In addition, the curves for each color do not show significant dispersion, indicating that this fixed-focus lens also has good correction for chromatic aberration, ensuring the imaging requirement of sharp images across the entire wavelength range.

[0138] Figure 10 This is a chromatic aberration curve of a fixed-focus lens provided in an embodiment of the present invention. The vertical direction represents the field of view, 0 indicates that it is on the optical axis, and the vertex in the vertical direction represents the maximum field of view; the dominant wavelength is 546.074 nm, and the horizontal direction represents the offset relative to the dominant wavelength, in micrometers (μm). Figure 10 It can be seen that the transverse chromatic aberration of different wavelengths is controlled within a reasonable range, indicating that the transverse chromatic aberration of this fixed-focus lens is well controlled and can meet the requirements of wide-spectrum applications across the entire wavelength range.

[0139] Figure 11 This is a schematic diagram of another fixed-focus lens provided in an embodiment of the present invention. Table 4 shows the structure of the lens. Figure 11 The specific parameters of the corresponding prime lens are as follows:

[0140] Table 4 Specific parameters of fixed focal length lenses

[0141]

[0142] Table 5 shows the parameter data of each lens in Example 2. The focal length f of the fixed-focus lens in Example 2 is 2.406mm and the aperture number F is 1.950.

[0143] Table 5. Design values ​​of optical physical parameters for the fixed-focus lens in Example 2.

[0144]

[0145] The surface number is assigned according to the order of the lenses' surfaces. "STO" indicates the aperture stop of a fixed-focus lens. The radius of curvature indicates the degree of curvature of the corresponding lens surface. A positive value means the surface bends towards the image plane, and a negative value means the surface bends towards the object plane. "Infinite" indicates that the surface is flat and the radius of curvature is infinite. The thickness indicates the central axial distance between the current surface and the next surface. Both the radius of curvature and the thickness are in mm. The material (Nd) indicates the refractive index, which represents the ability of the material between the current surface and the next surface to deflect light. A space indicates that the current position is air and the refractive index is 1. The material (Vd) indicates the Abbe number, which represents the dispersion characteristics of the material between the current surface and the next surface. A space indicates that the current position is air.

[0146] Table 6 shows the design values ​​of the aspherical parameters in Example 2:

[0147]

[0148] Continued from Table 6

[0149]

[0150] Where -6.079609891854E-03 indicates that the a4 coefficient of face number 3 is -6.079609891854 × 10 -3 .

[0151] Figure 12 The axial aberration curve of another fixed-focus lens provided in this embodiment of the invention is shown. The vertical direction is the normalized aperture, 0 indicates that it is on the optical axis, and the vertical vertex represents the maximum pupil radius. The horizontal direction represents the offset relative to the image plane, in millimeters (mm). Figure 12 Different linear curves represent different wavelengths of system imaging, by Figure 12 It can be seen that the axial aberrations of the normalized aperture at different wavelengths (0~1.0) are all controlled within the range of (-0.04mm, +0.04mm), indicating that the spherical aberration of this fixed-focus lens is well controlled at all wavelengths, which can meet the requirements of wide-spectrum applications. In addition, at the pupil positions of 0.5~0.9, there is no obvious chromatic aberration between visible light and infrared light, which meets the basic requirement of clear imaging at night and achieves the effect of clear imaging across the entire spectral band.

[0152] Figure 13 This is another fixed-focus lens with a 0-degree field of view, provided as an embodiment of the present invention. Figure 14 The optical fan pattern of another fixed-focus lens with a field of view of 25.94 degrees is provided for an embodiment of the present invention. Figure 15 The following is a fan-shaped pattern of a fixed-focus lens with a field of view of 43.64 degrees, provided as an embodiment of the present invention. Figure 16 The optical fan pattern of another fixed-focus lens with a 61.45-degree field of view is provided in an embodiment of the present invention. Figure 17 The optical fan pattern of another fixed-focus lens with a field of view of 69.98 degrees is provided for an embodiment of the present invention. Figure 18 The optical fan pattern of another fixed-focus lens with a field of view of 78.25 degrees is provided in an embodiment of the present invention. Figure 19 Another fixed-focus lens provided in this embodiment of the invention has an optical fan pattern at a field of view of 89.71 degrees, as shown below. Figures 13-19 As shown, the horizontal axis in the figure represents the normalized beam aperture, and the vertical axis represents the transverse aberration. Ideally, each curve should perfectly coincide with the horizontal axis, at which point all rays in that field of view focus at the same point on the image plane; the vertical axis in a single image can also represent the maximum dispersion range of the beam on the ideal image plane. The fan diagram not only reflects monochromatic aberrations of different wavelengths but also indicates the magnitude of transverse chromatic aberration. Figures 13-19 It can be seen that this fixed-focus lens closely approximates the horizontal axis at all wavelengths across all fields of view, indicating that its transverse aberrations at all wavelengths are well corrected. In addition, the curves for each color do not show significant dispersion, indicating that this fixed-focus lens also has good correction for chromatic aberration, ensuring the imaging requirement of sharp images across the entire wavelength range.

[0153] Figure 20 This is a chromatic aberration curve of a fixed-focus lens provided in an embodiment of the present invention. The vertical direction represents the field of view, 0 indicates it is on the optical axis, and the vertex in the vertical direction represents the maximum field of view. The dominant wavelength is 546.074 nm, and the horizontal direction represents the offset relative to the dominant wavelength, in micrometers (μm). Figure 20 It can be seen that the transverse chromatic aberration of different wavelengths is controlled within a reasonable range, indicating that the transverse chromatic aberration of this fixed-focus lens is well controlled and can meet the requirements of wide-spectrum applications across the entire wavelength range.

[0154] Figure 21 This is a schematic diagram of another fixed-focus lens provided in an embodiment of the present invention. Table 7 shows the structure of the lens. Figure 21 The specific parameters of the corresponding prime lens are as follows:

[0155] Table 7 Specific parameters of fixed focal length lenses

[0156]

[0157] Table 8 shows the parameter data of each lens in Example 3. The focal length f of the fixed-focus lens in Example 3 is 2.437mm and the aperture number F is 2.294.

[0158] Table 8 Design values ​​of optical physical parameters for the fixed-focus lens in Example 3

[0159]

[0160] The surface number is assigned according to the order of the lenses' surfaces. "STO" indicates the aperture stop of a fixed-focus lens. The radius of curvature indicates the degree of curvature of the corresponding lens surface. A positive value means the surface bends towards the image plane, and a negative value means the surface bends towards the object plane. "Infinite" indicates that the surface is flat and the radius of curvature is infinite. The thickness indicates the central axial distance between the current surface and the next surface. Both the radius of curvature and the thickness are in mm. The material (Nd) indicates the refractive index, which represents the ability of the material between the current surface and the next surface to deflect light. A space indicates that the current position is air and the refractive index is 1. The material (Vd) indicates the Abbe number, which represents the dispersion characteristics of the material between the current surface and the next surface. A space indicates that the current position is air.

[0161] Table 9 shows the design values ​​of the aspherical parameters in Example 3:

[0162]

[0163] Continued from Table 9

[0164]

[0165] Where -8.454162136269E-03 indicates that the a4 coefficient of face number 3 is -8.454162136269 × 10 -3 .

[0166] Figure 22 The axial aberration curve of another fixed-focus lens provided in this embodiment of the invention is shown. The vertical direction is the normalized aperture, 0 indicates that it is on the optical axis, and the vertical vertex represents the maximum pupil radius. The horizontal direction represents the offset relative to the image plane, in millimeters (mm). Figure 22 Different linear curves represent different wavelengths of system imaging, by Figure 22 It can be seen that the axial aberrations of the normalized aperture at different wavelengths (0~1.0) are all controlled within the range of (-0.02mm, +0.02mm), indicating that the spherical aberration of this fixed-focus lens is well controlled at all wavelengths, which can meet the requirements of wide-spectrum applications. In addition, at the pupil positions of 0.5~0.9, there is no obvious chromatic aberration between visible light and infrared light, which meets the basic requirement of clear imaging at night and achieves the effect of clear imaging across the entire spectral band.

[0167] Figure 23 This invention provides another fixed-focus lens with a 0-degree field of view, and its optical fan pattern. Figure 24 This is another fixed-focus lens with a field of view of 25.85 degrees, provided as an embodiment of the present invention. Figure 25 This is another example of a fixed-focus lens with a field of view of 43.30 degrees, provided in an embodiment of the present invention. Figure 26 This invention provides another fixed-focus lens with a 61.00-degree field of view, and its optical fan pattern is shown in the embodiment of the invention. Figure 27 This is another fixed-focus lens with a field of view of 69.67 degrees, provided as an embodiment of the present invention. Figure 28 This is another optical fan pattern of a fixed-focus lens with a field of view of 78.29 degrees, provided as an embodiment of the present invention. Figure 29 Another fixed-focus lens provided in this embodiment of the invention has a fan-shaped optical pattern at a field of view of 89.49 degrees, as shown below. Figures 23-29 As shown, the horizontal axis in the figure represents the normalized beam aperture, and the vertical axis represents the transverse aberration. Ideally, each curve should perfectly coincide with the horizontal axis, at which point all rays in that field of view focus at the same point on the image plane; the vertical axis in a single image can also represent the maximum dispersion range of the beam on the ideal image plane. The fan diagram not only reflects monochromatic aberrations of different wavelengths but also indicates the magnitude of transverse chromatic aberration. Figures 23-29 It can be seen that this fixed-focus lens closely approximates the horizontal axis at all wavelengths across all fields of view, indicating that its transverse aberrations at all wavelengths are well corrected. In addition, the curves for each color do not show significant dispersion, indicating that this fixed-focus lens also has good correction for chromatic aberration, ensuring the imaging requirement of sharp images across the entire wavelength range.

[0168] Figure 30 This is a chromatic aberration curve of a fixed-focus lens provided in an embodiment of the present invention. The vertical direction represents the field of view, 0 indicates it is on the optical axis, and the vertex in the vertical direction represents the maximum field of view. The dominant wavelength is 546.074 nm, and the horizontal direction represents the offset relative to the dominant wavelength, in micrometers (μm). Figure 30 It can be seen that the transverse chromatic aberration of different wavelengths is controlled within a reasonable range, indicating that the transverse chromatic aberration of this fixed-focus lens is well controlled and can meet the requirements of wide-spectrum applications across the entire wavelength range.

[0169] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A fixed focus lens characterized by, The system includes a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, an aperture stop, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, and a ninth lens with negative optical power, arranged sequentially from the object side to the image side along the optical axis. The first lens, the third lens, and the seventh lens are all glass spherical lenses, the sixth lens is a glass aspherical lens, and the second lens, the fourth lens, the fifth lens, the eighth lens, and the ninth lens are all plastic aspherical lenses. The fixed-focus lens satisfies the following condition: 1.36≤H / f≤1.38; Where f represents the focal length of the fixed-focus lens, and H represents the vertical height of the intersection point of the principal ray of the maximum field of view and the image plane; Along the optical axis from the object side to the image side, the first lens is a convex-concave lens, the second lens is a convex-concave lens, the third lens is a concave-convex lens, the fourth lens is a concave-convex lens, the fifth lens is a convex-concave lens, the sixth lens is a convex-convex lens, the seventh lens is a concave-concave lens, the eighth lens is a convex-convex lens, and the ninth lens is a convex-concave lens.

2. The fixed-focus lens according to claim 1, characterized in that, The third lens, the fifth lens, and the sixth lens satisfy the following condition: 1.85≤Nd3≤2.00; 23.79≤Vd3≤25.43; 1.64≤Nd5≤1.67; 19.28≤Vd5≤23.92; 1.69≤Nd6≤1.81; 40.91≤Vd6≤48.06; Wherein, Nd3, Nd5, and Nd6 represent the refractive indices of the third lens, the fifth lens, and the sixth lens, respectively, and Vd3, Vd5, and Vd6 represent the Abbe numbers of the third lens, the fifth lens, and the sixth lens, respectively.

3. The fixed-focus lens according to claim 1, characterized in that, The focal lengths of the first lens and the second lens satisfy the following condition: -8.74≤(f1+f2) / f≤-7.06; Where f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, and f represents the focal length of the fixed-focus lens.

4. A fixed-focus lens according to claim 1, characterized in that, The diameter of the first lens and the total optical length of the fixed-focus lens satisfy the following condition: 0.58≤ΦL1 / TTL≤0.71; Wherein, ΦL1 represents the lens diameter of the first lens, and TTL represents the total optical length of the fixed-focus lens.

5. The fixed-focus lens according to claim 1, characterized in that, The focal lengths of the third lens and the fourth lens satisfy the following condition: 10.57≤(f3+f4) / f≤12.42; Where f3 represents the focal length of the third lens, f4 represents the focal length of the fourth lens, and f represents the focal length of the fixed-focus lens.

6. The fixed-focus lens according to claim 1, characterized in that, The focal lengths of the fifth lens and the sixth lens satisfy the following condition: 5.1≤(f5+f6) / f≤5.82; Where f5 represents the focal length of the fifth lens, f6 represents the focal length of the sixth lens, and f represents the focal length of the fixed-focus lens.

7. The fixed-focus lens according to claim 1, characterized in that, The focal lengths of the seventh lens and the eighth lens satisfy the following condition: 2.37≤(f7+f8) / f≤2.74; Wherein, f7 represents the focal length of the seventh lens, f8 represents the focal length of the eighth lens, and f represents the focal length of the fixed-focus lens.

8. The fixed-focus lens according to claim 1, characterized in that, The focal length of the ninth lens satisfies the following condition: -58.59≤f9 / f≤-16.8; Where f9 represents the focal length of the ninth lens, and f represents the focal length of the fixed-focus lens.

9. The fixed-focus lens according to claim 1, characterized in that, The fixed-focus lens satisfies the following condition: 1.95≤F≤2.294； 0.11≤BFL / TTL≤0.13; Wherein, F represents the aperture number of the fixed-focus lens, BFL represents the distance from the vertex of the last optical surface of the fixed-focus lens to the image plane, and TTL represents the total optical length of the fixed-focus lens.

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