Large-aperture day and night confocal fisheye lens

Abstract

The invention relates to the technical field of optical lenses, in particular to a large-aperture day and night confocal fisheye lens. The lens is sequentially provided with a first lens, a second lens, a third lens and a fourth lens from an object side to an image side along an optical axis, the second lens has negative focal power; the third lens has negative focal power; the fourth lens has negative focal power; the fifth lens has positive focal power; the sixth lens has positive focal power; the seventh lens has negative focal power; the eighth lens has positive focal power; the ninth lens has positive focal power; the tenth lens has negative focal power; the eleventh lens has positive focal power; the twelfth lens, the seventh lens and the eighth lens which have positive focal power, and the ninth lens and the tenth lens which have positive focal power form a balsaming lens. The lens adopts 12 spherical glass lenses, system aberration is effectively corrected, the aperture F # is larger than or equal to 1.0, the focal length f is larger than or equal to 1.38 mm, the lens can be matched with a high-pixel chip, the optical performance of the system is guaranteed, and the lens can achieve large-aperture day and night confocal.

Description

Technical Field

[0001] The present invention relates to the technical field of optical lenses, in particular to a large-aperture day and night confocal fisheye lens. Background Art

[0002] A fisheye lens is a specialized lens with a short focal length and ultra-wide angle, typically ranging from 180° to 270°. Its visual effect is similar to a fish observing the surface of the water. To achieve this exceptionally wide field of view, the front lens element of a fisheye lens is short in diameter and bulges outward in a parabolic shape, resembling a fish's eye, hence the name. Due to its exceptionally wide field of view, fisheye lenses are widely used in security surveillance, sports cameras, and automotive cameras.

[0003] With the continuous development of optical technology and the security industry, surveillance equipment is increasingly being used. The market demands a wide field of view, large image area, large aperture, high-definition resolution exceeding 4K, smaller lens size, and high edge illumination. Furthermore, functional requirements include waterproofing and day / night parfocality. Existing fisheye lenses have a small aperture and low resolution, making it difficult to meet this growing demand. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a large aperture day and night confocal fisheye lens, which adopts 12 glass spherical lenses, has a total lens length of ≤30mm, and an aperture F#≥1.0, which can meet the current market demand for fisheye lenses in security monitoring and other fields.

[0005] The purpose of the present invention is achieved through the following technical solutions: A large aperture day and night confocal fisheye lens, wherein the surface of the lens adjacent to the object plane is defined as the object side surface, and the surface of the lens adjacent to the image plane is defined as the image side surface. The lens is arranged in order from the object side to the image side along the optical axis of the lens: a first lens, wherein the first lens is a spherical glass lens with negative optical power, the object-side surface of the lens being convex and the image-side surface being concave; a second lens, the second lens being a spherical glass lens with negative optical power, the object-side surface of the lens being convex and the image-side surface being concave; a third lens, the third lens being a spherical glass lens with negative optical power, the object-side surface of the third lens being convex and the image-side surface being concave; a fourth lens, the fourth lens being a spherical glass lens with negative optical power, the object-side surface of the fourth lens being concave, and the image-side surface of the fourth lens being concave; a fifth lens element, the fifth lens element being a spherical glass lens with positive optical power, having a convex object-side surface and a convex image-side surface; a sixth lens, the sixth lens being a spherical glass lens with positive refractive power, having a convex object-side surface and a convex image-side surface; a seventh lens element, the seventh lens element being a spherical glass lens with negative optical power, having a convex object-side surface and a concave image-side surface; an eighth lens element, the eighth lens element being a spherical glass lens with positive refractive power, having a convex object-side surface and a convex image-side surface; a ninth lens element, the ninth lens element being a spherical glass lens with positive refractive power, having a convex object-side surface and a convex image-side surface; a tenth lens, the tenth lens being a spherical glass lens with negative optical power, the object-side surface of the tenth lens being concave and the image-side surface being convex; an eleventh lens, the eleventh lens being a spherical glass lens with positive refractive power, the object-side surface of the lens being convex, and the image-side surface of the lens being convex; a twelfth lens, the twelfth lens being a spherical glass lens with positive refractive power, the object-side surface of the lens being convex and the image-side surface being concave; The image-side surface of the seventh lens and the object-side surface of the eighth lens are cemented together to form a first cemented lens; The image-side surface of the ninth lens and the object-side surface of the tenth lens are cemented together to form a second cemented lens.

[0006] Furthermore, the lens is further provided along the lens optical axis: an aperture stop, the aperture stop being disposed between the sixth lens and the seventh lens, or the aperture stop being disposed between the fifth lens and the sixth lens; a filter, the filter being arranged on the image side surface of the twelfth lens; A protective glass and an image acquisition element, wherein the protective glass is integrated on the image acquisition element, and the image acquisition element is arranged on the image side of the protective glass.

[0007] Furthermore, in the present invention, taking into account the aberrations of the optical system and the problems of different focusing object distances, the focal lengths, refractive indices, and curvature radii of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, and the twelfth lens respectively satisfy the following conditions:

[0008] Wherein, f1 is the focal length of the first lens, ND1 is the refractive index of the first lens, R11 is the radius of curvature of the object side surface of the first lens, and R12 is the radius of curvature of the image side surface of the first lens; f2 is the focal length of the second lens, ND2 is the refractive index of the second lens, R21 is the radius of curvature of the object side surface of the second lens, and R22 is the radius of curvature of the image side surface of the second lens; f3 is the focal length of the third lens, ND3 is the refractive index of the third lens, R31 is the radius of curvature of the object side surface of the third lens, and R32 is the radius of curvature of the image side surface of the third lens; f4 is the focal length of the fourth lens, ND4 is the refractive index of the fourth lens, R41 is the radius of curvature of the object side surface of the fourth lens, and R42 is the radius of curvature of the image side surface of the fourth lens; f5 is the focal length of the fifth lens, ND5 is the refractive index of the fifth lens, R51 is the radius of curvature of the object side surface of the fifth lens, and R52 is the radius of curvature of the image side surface of the fifth lens; f6 is the focal length of the sixth lens, ND6 is the refractive index of the sixth lens, R61 is the radius of curvature of the object side surface of the sixth lens; R62 is the radius of curvature of the object side surface of the sixth lens; f7 is the focal length of the seventh lens, ND7 is the refractive index of the seventh lens, R71 is the radius of curvature of the object side surface of the seventh lens, and R72 is the radius of curvature of the image side surface of the seventh lens; f8 is the focal length of the eighth lens, ND8 is the refractive index of the eighth lens, R81 is the radius of curvature of the object side surface of the eighth lens, and R82 is the radius of curvature of the image side surface of the eighth lens; f9 is the focal length of the ninth lens, ND9 is the refractive index of the ninth lens, R91 is the radius of curvature of the object side surface of the ninth lens, and R92 is the radius of curvature of the image side surface of the ninth lens; f10 is the focal length of the tenth lens, ND10 is the refractive index of the tenth lens, R101 is the radius of curvature of the object side surface of the tenth lens, and R102 is the radius of curvature of the image side surface of the tenth lens; f11 is the focal length of the eleventh lens, ND11 is the refractive index of the eleventh lens, R111 is the radius of curvature of the object side of the eleventh lens; R112 is the radius of curvature of the object side of the eleventh lens; f12 is the focal length of the twelfth lens, ND12 is the refractive index of the twelfth lens, R121 is the radius of curvature of the object side surface of the twelfth lens, and R122 is the radius of curvature of the image side surface of the twelfth lens; Focal length: The "+" sign indicates that the lens has positive focal power, and the "-" sign indicates that the lens has negative focal power. The unit is mm; Curvature radius: The "+" sign indicates that the surface is curved toward the image plane, and the "-" sign indicates that the surface is curved toward the object plane. The unit is mm.

[0009] Furthermore, in order to achieve better performance of the optical system, the present invention requires reasonable selection of lens materials, reasonable allocation of focal lengths of each lens, and reasonable optimization of the optical system during the design process to correct system aberrations. Ultimately, the performance of the optical system is optimized. The ratio of the focal length of each lens to the total focal length of the lens must also meet the following conditions: -11.1≤f1 / f≤-10.81; -8.36≤f2 / f≤-7.35; -8.75≤f3 / f≤-6.79; -2.40≤f4 / f≤-2.24; 3.64≤f5 / f≤4.00; 7.56≤f6 / f≤8.97; -4.61≤f7 / f≤-3.76; 3.82≤f8 / f≤4.16; 4.01≤f9 / f≤4.36; -3.68≤f10 / f≤-3.06; 5.69≤f11 / f≤6.46; 7.36≤f12 / f≤8.88; 23.55<f78 / f<36.89; -47.86<f91 / f<-22.19.

[0010] In the relationship, f is the focal length of the lens optical system, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f7 is the focal length of the seventh lens, f8 is the focal length of the eighth lens, f9 is the focal length of the ninth lens, f10 is the focal length of the tenth lens, f11 is the focal length of the eleventh lens, f12 is the focal length of the twelfth lens, f78 is the focal length of the first cemented lens, and f91 is the focal length of the second cemented lens.

[0011] Furthermore, in the present invention, The aperture of the lens is F#, which satisfies F#≥1.0; The field of view of the lens is FOV, which satisfies FOV≤200°; The total optical length of the lens is TTL, satisfying TTL≤30mm; The total focal length of the lens is f, which satisfies f≥1.38mm; The optical back focus of the lens is OBFL, which satisfies OBFL≥3mm.

[0012] Furthermore, in the present invention, the lens also satisfies the following relationship: IC / TTL ≥ 0.14; TTL / f≤20.6; OBFL / TTL ≥ 0.1; In the relationship, f is the total focal length of the lens, TTL is the total optical length of the lens, OBFL is the optical back focus of the lens, the optical back focus of the lens is the distance from the point on the image side of the twelfth lens closest to the image plane to the image plane, and IC is the total image height of the chip equipped with the lens system.

[0013] The beneficial effects of the present invention are: The present invention adopts 12 spherical glass lenses, and through the matching of different shapes of lenses and reasonable optical power distribution, the lens has good optical performance and a compact and unburdened structure.

[0014] In terms of performance, 12 spherical glass lenses can effectively correct system aberrations, ensure the system's optical performance, and enable the lens to achieve large aperture day and night focus; the entire optical system meets the aperture F#≥1.0, has a large light-transmitting aperture, a focal length f≥1.38mm, and the lens has good imaging performance in all fields of view, which can be matched with high-pixel chips.

[0015] Structurally, the lens can produce clear images at high temperatures of +85°C and low temperatures of -40°C through the coordination of different materials and lenses with reasonable optical focal length. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the optical structure of embodiment 1 of the present invention; Figure 2 This is the MTF curve of visible light 0.435-0.656 μm (200 lp / mm) in Example 1 of the present invention; Figure 3 This is the MTF curve of infrared light at 0.850 μm (200 lp / mm) in Example 1 of the present invention; Figure 4 This is a high-temperature +85°C defocus curve for visible light 0.435-0.656 μm (125 lp / mm) in Example 1 of the present invention; Figure 5 This is a low-temperature -40°C defocus curve for visible light 0.435-0.656 μm (125 lp / mm) in Example 1 of the present invention; Figure 6 This is a relative illumination diagram of visible light at 0.546 μm in Example 1 of the present invention; Figure 7 Schematic diagram of the optical structure of embodiment 2 of the present invention; Figure 8 This is the MTF curve of visible light 0.435-0.656 μm (200 lp / mm) in Example 2 of the present invention; Figure 9 This is the MTF curve of infrared light 0.850μm (200lp / mm) in Example 2 of the present invention; Figure 10This is a high-temperature +85°C defocus curve for visible light 0.435-0.656 μm (125 lp / mm) in Example 2 of the present invention; Figure 11 This is a low-temperature -40°C defocus curve for visible light 0.435-0.656 μm (125 lp / mm) in Example 2 of the present invention; Figure 12 This is the relative illumination diagram of visible light at 0.546 μm in Example 2 of the present invention; Reference numerals: 1 - first lens, 2 - second lens, 3 - third lens, 4 - fourth lens, 5 - fifth lens, 6 - sixth lens, 7 - seventh lens, 8 - eighth lens, 9 - ninth lens, 10 - tenth lens, 11 - eleventh lens, 12 - twelfth lens, 13 - aperture stop, 14 - filter, 15 - protective glass, 16 - image acquisition element. DETAILED DESCRIPTION

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. In this specification, the expressions first, second, third, etc. are only used to distinguish one feature from another and do not represent any limitation on the features. The shape of the spherical or aspherical surface is not limited to the spherical or aspherical shape shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0018] In the present invention, the paraxial region refers to the region near the optical axis. If a lens surface is convex and the position 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 position of the concave surface is undefined, it means that the lens surface is concave at least in the paraxial region; if a lens surface is not defined as convex, concave, or flat, it means that the lens surface can be convex, concave, or flat. 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.

[0019] Unless otherwise defined, all terms (including technical and scientific terms) used in the present invention have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) 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 explicitly defined in this invention.

[0020] It should be noted that the embodiments and features of the embodiments of the present invention may be combined with each other without conflict. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the scope of protection of the present invention.

[0021] The present invention provides a large-aperture day-night confocal fisheye lens. The surface of the lens adjacent to the object plane is the object-side surface, and the surface of the lens adjacent to the image plane is the image-side surface. A first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8, a ninth lens 9, a tenth lens 10, an eleventh lens 11, and a twelfth lens 12 are arranged in sequence along the lens optical axis from the object side to the image side. The lens is further provided with an aperture stop 13, a filter 14, a protective glass 15, and an image capture element 16 along the lens optical axis. The aperture stop 13 is located between the sixth lens 6 and the seventh lens 7 or between the fifth lens 5 and the sixth lens 6. The filter 14 is disposed on the image-side surface of the twelfth lens 12. The image capture element 16 is disposed on the image-side surface of the protective glass 15. The protective glass 15 is integrated with the image capture element 16.

[0022] in: The first lens 1 is a spherical glass lens with negative optical power, whose object side surface is convex and image side surface is concave; The second lens 2 is a spherical glass lens with negative optical power, whose object side surface is convex and image side surface is concave; The third lens 3 is a spherical glass lens with negative optical power, whose object side surface is convex and image side surface is concave; The fourth lens element 4 is a spherical glass lens with negative optical power, with its object-side surface being concave and its image-side surface being concave; The fifth lens 5 is a spherical glass lens with positive refractive power, with a convex object-side surface and a convex image-side surface; The sixth lens element 6 is a spherical glass lens with positive refractive power, with a convex object-side surface and a convex image-side surface; The seventh lens element 7 is a spherical glass lens with negative optical power, whose object-side surface is convex and image-side surface is concave; The eighth lens element 8 is a spherical glass lens with positive refractive power, with a convex object-side surface and a convex image-side surface. The ninth lens element 9 is a spherical glass lens with positive refractive power, with a convex object-side surface and a convex image-side surface. The tenth lens 10 is a spherical glass lens with negative optical power, whose object side surface is concave and image side surface is convex; The eleventh lens 11 is a spherical glass lens with positive refractive power, with a convex object-side surface and a convex image-side surface; The twelfth lens 12 is a spherical glass lens with positive refractive power, the object side surface of which is convex and the image side surface is concave; The image-side surface of the seventh lens element 7 and the object-side surface of the eighth lens element 8 are cemented together to form a first cemented lens. The image-side surface of the ninth lens element 9 and the object-side surface of the tenth lens element 10 are cemented together to form a second cemented lens. In the present invention, in order to make the optical system present better performance, we must reasonably select lens materials, reasonably allocate the focal lengths of each lens, and reasonably optimize the optical system during the design process to correct the aberrations of the system, and ultimately optimize the performance of the optical system. In the present invention, the focal length of the first lens 1 is f1, the focal length of the second lens 2 is f2, the focal length of the third lens 3 is f3, the focal length of the fourth lens 4 is f4, the focal length of the fifth lens 5 is f5, the focal length of the sixth lens 6 is f6, the focal length of the seventh lens 7 is f7, the focal length of the eighth lens 8 is f8, the focal length of the ninth lens 9 is f9, the focal length of the tenth lens 10 is f10, the focal length of the eleventh lens 11 is f11, the focal length of the twelfth lens 12 is f12, the focal length of the first cemented lens is f78, the focal length of the second cemented lens is f91, the total focal length of the lens is f, and the ratio of the focal length of each lens to the total focal length of the system meets the following conditions: -11.1≤f1 / f≤-10.81; -8.36≤f2 / f≤-7.35; -8.75≤f3 / f≤-6.79; -2.40≤f4 / f≤-2.24; 3.64≤f5 / f≤4.00; 7.56≤f6 / f≤8.97; -4.61≤f7 / f≤-3.76; 3.82≤f8 / f≤4.16; 4.01≤f9 / f≤4.36; -3.68≤f10 / f≤-3.06; 5.69≤f11 / f≤6.46; 7.36≤f12 / f≤8.88; 23.55<f78 / f<36.89; -47.86<f91 / f<-22.19.

[0023] In the present invention, taking into account the aberrations of the optical system and the problems of different focusing object distances, the focal lengths, refractive indices, and curvature radii of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the eighth lens 8, the ninth lens 9, the tenth lens 10, the eleventh lens 11, and the twelfth lens 12 respectively meet the following conditions:

[0024] Focal length: The "+" sign indicates that the lens has positive focal power, and the "-" sign indicates that the lens has negative focal power. The unit is mm; Curvature radius: The "+" sign indicates that the surface is curved toward the image plane, and the "-" sign indicates that the surface is curved toward the object plane. The unit is mm.

[0025] In the present invention, f is the total focal length of the lens, TTL is the total optical length of the lens, OBFL is the optical back focus of the lens, which is the distance from the point on the image side of the twelfth lens closest to the image plane to the image plane, and IC is the total image height of the chip used in the lens system, and they satisfy the following relationship: IC / TTL ≥ 0.14; TTL / f≤20.6; OBFL / TTL ≥ 0.1; In the present invention, the aperture of the lens is F#, which satisfies F#≥1.0; The field of view of the lens is FOV, which satisfies FOV≤200°; The total optical length of the lens is TTL, satisfying TTL≤30mm; The total focal length of the lens is f, which satisfies f≥1.38mm; The optical back focus of the lens is OBFL, which satisfies OBFL≥3mm.

[0026] The following describes a specific embodiment of the invention based on the above-mentioned configuration, thereby specifically illustrating the large aperture day and night confocal fisheye lens of the invention. In order to better understand and implement the invention, the invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0027] The data of the specific embodiment of the present invention are summarized in Table 1 below.

[0028] Table 1

[0029] Example 1 refer to Figure 1, which is a schematic diagram of the optical structure of Example 1. In this embodiment, the field of view angle FOV of the lens is 186°, the aperture value F# of the lens is 1.0, the total focal length f of the lens is 1.38 mm, the total optical length TTL of the lens is 30 mm, and the optical back focus OBFL of the lens is 3.7 mm.

[0030] The lenses in this embodiment are arranged in the following order from the object side to the image side along the lens optical axis: The first lens 1 is a spherical glass lens with negative optical power, the object side surface of which is convex and the image side surface is concave; The second lens 2 is a spherical glass lens with negative optical power, the object side surface of which is convex and the image side surface is concave; The third lens 3 is a spherical glass lens with negative optical power, whose object-side surface is convex and image-side surface is concave; The fourth lens 4 is a spherical glass lens with negative optical power, with a concave object-side surface and a concave image-side surface; The fifth lens 5 is a spherical glass lens with positive refractive power, with a convex object-side surface and a convex image-side surface; The sixth lens 6 is a spherical glass lens with positive refractive power, with a convex object-side surface and a convex image-side surface; an aperture stop 13, the aperture stop being located between the sixth lens element 6 and the seventh lens element 7; The seventh lens element 7 is a spherical glass lens with negative optical power, whose object-side surface is convex and image-side surface is concave; The eighth lens element 8 is a spherical glass lens with positive refractive power, with a convex object-side surface and a convex image-side surface; The ninth lens element 9 is a spherical glass lens with positive refractive power, with a convex object-side surface and a convex image-side surface; The tenth lens 10 is a spherical glass lens with negative optical power, whose object-side surface is concave and image-side surface is convex; The eleventh lens 11 is a spherical glass lens with positive refractive power, with a convex object-side surface and a convex image-side surface; The twelfth lens 12 is a spherical glass lens with positive refractive power, the object side surface of which is convex and the image side surface of which is concave; a filter 14, the filter 14 being disposed on the image side surface of the twelfth lens; The protective glass 15 and the image acquisition element 16 , the protective glass 15 is integrated on the image acquisition element 16 , and the image acquisition element 16 is arranged on the image side of the protective glass 15 .

[0031] The image-side surface of the seventh lens element 7 and the object-side surface of the eighth lens element 8 are cemented together to form a first cemented lens; the image-side surface of the ninth lens element 9 and the object-side surface of the tenth lens element 10 are cemented together to form a second cemented lens. These two sets of cemented lenses effectively control chromatic aberration and reduce sensitivity to tolerances such as tilt and deflection that can occur during lens assembly.

[0032] In this embodiment, the curvature radius (unit: mm), center thickness d (unit: mm), refractive index (ND), and Abbe constant (VD) of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the eighth lens 8, the ninth lens 9, the tenth lens 10, the eleventh lens 11, and the twelfth lens 12 are shown in Table 2.

[0033] Table 2

[0034] In Table 2, the surface numbers are numbered according to the order of the surfaces of each lens, where "S11" represents the object-side surface of the first lens, "S12" represents the image-side surface of the first lens, and so on; the radius of curvature represents the degree of curvature of the lens surface, with a positive value indicating that the surface is curved toward the image side, and a negative value indicating that the surface is curved toward the object side, where "Infinity" indicates that the surface is flat; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the light deflection ability of the current lens material, and the Abbe number represents the dispersion characteristics of the current lens material to light.

[0035] refer to Figure 2 The following graph shows the MTF curves for different fields of view of the lens of this embodiment at visible light wavelengths of 0.435-0.656μm and a spatial frequency of 200lp / mm. The horizontal axis represents spatial frequency, and the vertical axis represents MTF value. As can be seen from the graph, at a spatial frequency of 200lp / mm, the MTF values ​​are generally above 0.3 except for the maximum field of view, and the MTF value at the maximum field of view is also above 0.2, indicating that the lens has high resolving power and is compatible with chips with higher pixel counts.

[0036] refer to Figure 3 Figure 2 shows the MTF curve for the lens of this embodiment at an infrared wavelength of 0.85μm and a spatial frequency of 200lp / mm. As can be seen from the figure, at a spatial frequency of 200lp / mm, the lens's MTF values ​​for the entire field of view are 0.25 or higher, and its center field MTF value is above 0.6. This ensures clear images during nighttime shooting, enabling all-weather high-definition surveillance.

[0037] refer to Figure 4 、 Figure 5The following are MTF defocus curves for the lens of this embodiment at a visible light wavelength of 0.435-0.656μm and a spatial frequency of 125lp / mm at temperatures of +85°C and -40°C, respectively. As can be seen from the figures, the defocus is less than 2μm at both +85°C and -40°C, ensuring high resolution at both temperatures, enabling high-definition image capture.

[0038] refer to Figure 6 The figure below shows the relative illumination curve for the lens of this embodiment at 0.546μm in the visible light range. As can be seen from the figure, the relative illumination at the maximum field of view is above 40%, indicating sufficient light input, ensuring that the lens can be used even in dim environments, and that there is no vignetting at the edges of the field of view in real-life images.

[0039] Example 2 refer to Figure 7 , which is a schematic diagram of the optical structure of this embodiment 2. In this embodiment, the lens field of view FOV = 180°, the lens aperture value F# = 1.0, the total focal length f of the lens optical system = 1.45 mm, the total optical length TTL of the lens = 30 mm, and the optical back focus OBFL of the lens = 3 mm.

[0040] In the lens of this embodiment, the arrangement structure of each lens from the object side to the image side along the lens optical axis is the same as that of Example 1, except that the aperture stop is arranged between the fifth lens and the sixth lens.

[0041] In this embodiment, the curvature radius (unit: mm), center thickness d (unit: mm), refractive index (ND), and Abbe constant (VD) of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the eighth lens 8, the ninth lens 9, the tenth lens 10, the eleventh lens 11, and the twelfth lens 12 are shown in Table 3.

[0042] Table 3

[0043] In Table 3, the surface numbers are numbered according to the order of the surfaces of each lens, where "S11" represents the object-side surface of the first lens, "S12" represents the image-side surface of the first lens, and so on. The radius of curvature represents the degree of curvature of the lens surface, with a positive value indicating that the surface is curved toward the image plane, and a negative value indicating that the surface is curved toward the object plane. "Infinity" indicates that the surface is flat. The thickness represents the axial distance from the center of the current surface to the next surface. The refractive index represents the light refracting ability of the current lens material. The Abbe number represents the dispersion characteristics of the current lens material to light.

[0044] refer to Figure 8The following graph shows the MTF curves for different fields of view for the lens of this embodiment at visible light wavelengths of 0.435-0.656μm and a spatial frequency of 200lp / mm. The horizontal axis represents spatial frequency, and the vertical axis represents MTF value. As can be seen from the graph, at a spatial frequency of 200lp / mm, the MTF values ​​for the entire field of view, except for the maximum field of view, are above 0.3, and the MTF value for the maximum field of view is also above 0.2, indicating that the lens has high resolving power and is compatible with chips with higher pixel counts.

[0045] refer to Figure 9 Figure 2 shows the MTF curve for the lens of this embodiment at an infrared wavelength of 0.85μm and a spatial frequency of 200lp / mm. As can be seen from the figure, at a spatial frequency of 200lp / mm, the MTF values ​​for the entire field of view, except for the maximum field of view, are above 0.3. This ensures clear images during nighttime shooting, enabling all-weather high-definition surveillance.

[0046] refer to Figure 10 、 Figure 11 The following are MTF defocus curves for the lens of this embodiment at temperatures of +85°C and -40°C, respectively, for visible light wavelengths of 0.435-0.656μm and a spatial frequency of 125lp / mm. As can be seen from the figures, the defocus is less than or equal to 4μm at both temperatures. This ensures the lens's resolving power at both temperatures, enabling high-definition capture.

[0047] refer to Figure 12 The figure shows the relative illumination curve of visible light at 0.546μm in this embodiment. As can be seen from the figure, the relative illumination at the maximum field of view is above 40%, and sufficient light input ensures that the lens can be used even in dim environments, and there is no vignetting at the edges of the field of view in the actual image.

[0048] It can be seen from the MTF curves, defocus curves, and relative illumination curves of the above embodiments that the optical lens provided by the present invention has the advantages of large aperture, high resolution, compatibility with high-pixel chips, high relative illumination, and the ability to achieve day and night confocality in high and low temperature environments.

[0049] The above description only represents several embodiments of the present invention, and the description is relatively specific and detailed, but it should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art may make various modifications and improvements without departing from the spirit of the present invention, and the present invention is intended to include such modifications and variations.

Claims

1. A large aperture day and night confocal fisheye lens, characterized by: Set along the lens optical axis from the object side to the image side in order: a first lens, wherein the first lens is a spherical glass lens with negative optical power; a second lens, the second lens being a spherical glass lens with negative optical power; a third lens, wherein the third lens is a spherical glass lens with negative optical power; a fourth lens, wherein the fourth lens is a spherical glass lens with negative optical power; a fifth lens element, wherein the fifth lens element is a spherical glass lens with positive optical power; a sixth lens, wherein the sixth lens is a spherical glass lens with positive optical power; a seventh lens, wherein the seventh lens is a spherical glass lens with negative optical power; an eighth lens, wherein the eighth lens is a spherical glass lens with positive optical power; a ninth lens, wherein the ninth lens is a spherical glass lens having positive optical power; a tenth lens, wherein the tenth lens is a spherical glass lens with negative optical power; an eleventh lens, wherein the eleventh lens is a spherical glass lens with positive refractive power; a twelfth lens, wherein the twelfth lens is a spherical glass lens with positive refractive power; The image-side surface of the seventh lens and the object-side surface of the eighth lens are cemented together to form a first cemented lens; The image-side surface of the ninth lens and the object-side surface of the tenth lens are cemented together to form a second cemented lens; The lens satisfies the following relationship: IC / TTL ≥ 0.14; TTL / f≤20.6; OBFL / TTL ≥ 0.1; In this equation, f is the total focal length of the lens, TTL is the total optical length of the lens, OBFL is the optical back focus distance of the lens, and IC is the full image height of the chip used in the lens system.

2. The large aperture day and night confocal fisheye lens according to claim 1, characterized in that: The lens also satisfies the following relationship: -11.1≤f1 / f≤-10.81; -8.36≤f2 / f≤-7.35; -8.75≤f3 / f≤-6.79; -2.40≤f4 / f≤-2.24; 3.64≤f5 / f≤4.00; 7.56≤f6 / f≤8.97; -4.61≤f7 / f≤-3.76; 3.82≤f8 / f≤4.16; 4.01≤f9 / f≤4.36; -3.68≤f10 / f≤-3.06; 5.69≤f11 / f≤6.46; 7.36≤f12 / f≤8.88; In the relationship, f is the total focal length of the lens, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f7 is the focal length of the seventh lens, f8 is the focal length of the eighth lens, f9 is the focal length of the ninth lens, f10 is the focal length of the tenth lens, f11 is the focal length of the eleventh lens, and f12 is the focal length of the twelfth lens.

3. The large aperture day and night confocal fisheye lens according to claim 1, characterized in that: The focal length of the first cemented lens is f78, which satisfies the following condition: 23.55<f78 / f<36.

89.

4. The large aperture day and night confocal fisheye lens according to claim 1, characterized in that: The focal length of the second cemented lens is f91, which satisfies the following condition: -47.86<f91 / f<-22.

19.

5. The large aperture day and night confocal fisheye lens according to claim 1, characterized in that: The aperture of the lens is F#, which satisfies F#≥1.

0.

6. The large aperture day and night confocal fisheye lens according to claim 1, characterized in that: The total focal length of the lens is f, which satisfies f≥1.38mm.

7. The large aperture day and night confocal fisheye lens according to claim 1, characterized in that: The total optical length of the lens is TTL, satisfying TTL≤30mm.

8. The large aperture day and night confocal fisheye lens according to claim 1, characterized in that: The focal lengths of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, and twelfth lenses are in the range of -16.095 to -14.932, -12.515 to -10.143, -12.077 to -9.846, -3.312 to -3.249, and +5.275 to +5. 521, +10.959~+12.384, -6.364~-5.454, +5.539~+5.741, +5.812~+6.017, -5.078~-4.436, +8.251~8.915, +10.669~+12.254, where the "+" sign indicates that the lens has positive power, and the "-" sign indicates that the lens has negative power. The unit of focal length is mm; The refractive index ranges of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens and the twelfth lens are 1.90-1.94, 1.81-1.85, 1.75-1.79, 1.90-1.94, 1.80-1.90, 1.74-1.83, 1.51-1.57, 1.80-1.90, 1.46-1.52, 1.46-1.52, 1.81-1.85 and 1.57-1.63 respectively; The object side surface radii of curvature corresponding to the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, and twelfth lenses, respectively, range from +16.451 to +22.038, +9.271 to +10.569, +6.801 to +7.055, -4.721 to -4.481, and +13.589 to +14. 751, +10.359~+15.220, +24.112~+66.235, +4.327~+4.355, +8.058~+9.099, -4.101~-4.098, +40.607~+97.199, +5.624~+6.502, where the "+" sign indicates that the surface is curved toward the image side, and the "-" sign indicates that the surface is curved toward the object side. The unit of the curvature radius is mm; The image side surface curvature radii corresponding to the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens and the twelfth lens are in the range of +7.255~+8.487, +4.219~+5.022, +3.343~+3.776, +9.253~+9.834 and -6.717~-6.10, respectively.

6. -59.918~-28.49, +4.327~+4.355, -6.894~-6.255, -4.101~-4.098, 120.124~+44.789, -5.566~-5.467, +14.254~+17.728, where the "+" sign indicates that the surface is curved toward the image side, and the "-" sign indicates that the surface is curved toward the object side. The unit of the curvature radius is mm.

9. The large aperture day and night confocal fisheye lens according to claim 1, characterized in that: The object side surface of the first lens is convex, and the image side surface is concave; The object side surface of the second lens is convex, and the image side surface is concave; The object side surface of the third lens is convex, and the image side surface is concave; The object-side surface of the fourth lens is concave, and the image-side surface is concave; 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 convex, and the image-side surface is concave; The object-side surface of the eighth lens is convex, and the image-side surface is convex; The object-side surface of the ninth lens is convex, and the image-side surface is convex; The object-side surface of the tenth lens is concave, and the image-side surface is convex; The object-side surface of the eleventh lens is convex, and the image-side surface is convex; The object-side surface of the twelfth lens is convex, and the image-side surface may be concave.

10. The large aperture day and night confocal fisheye lens according to claim 1, characterized in that: Also set along the lens optical axis: an aperture stop, the aperture stop being disposed between the sixth lens and the seventh lens, or the aperture stop being disposed between the fifth lens and the sixth lens; a filter, the filter being disposed on the image-side surface of the twelfth lens; A protective glass and an image acquisition element, wherein the protective glass is integrated on the image acquisition element, and the image acquisition element is arranged on the image side of the protective glass.

Images