Reverse telephoto optical lens, camera device and industrial detection equipment with same

Abstract

The application discloses a kind of anti-telescopic optical lens, camera device and the industrial detection equipment with it, lens is successively arranged eight lenses with focal power of negative-negative-positive-positive-negative-positive-positive-positive from object plane to image plane direction along optical axis, the object side surface of first lens and fourth lens is convex, its image side surface is concave;The image side surface of second lens is concave;Third lens and sixth lens are both double convex mirror;Fifth lens is double concave mirror;The image side surface of seventh lens and the object side surface of eighth lens are both convex;The optical axis distance between the image side surface of second lens and the object side surface of fourth lens is between 14.2mm and 22.5mm, and the central thickness of third lens is between 2.1mm and 3.5mm;Optical lens meets the overall focal length between 10.5mm and 13mm, and the ratio between lens assembly and focal length is between 4 and 5.5.The application provides a kind of to solve the problem that aberration is difficult to correct due to limited physical space.

Description

Technical Field

[0001] This invention relates to the field of optics, and more particularly to a retro-telescopic optical lens, a camera device, and an industrial testing equipment having the same. Background Technology

[0002] In industrial automation inspection, security monitoring, and machine vision, short focal length (e.g., 12mm and below) lenses are often used to achieve a large field of view (FOV) to cover a wider inspection range or acquire more scene information. Traditional large field of view lens designs typically prioritize compactness, with a low total track length (TLT). TTL ) and the entire focal length of the lens ( f The ratio of ) TTL / f The focal length is typically small (generally between 1.0 and 2.5). This type of lens shortens its physical length by optimizing the curvature of the lens elements (such as by using a reverse telephoto structure) to place the imaging plane closer to the front element.

[0003] Although traditional short focal length, wide field-of-view lenses have advantages in physical length, they suffer from the following technical challenges in practical applications: On the one hand, due to the limited space layout of the lens assembly, especially in order to compress... TTL Sacrificing optical path length makes it difficult to perfectly correct spherical aberration, chromatic aberration, and field curvature within a limited space. In ultra-wide fields of view, the image quality (MTF) at the edges of the field of view drops sharply, and the edges of the image are prone to blurring, stretching, distortion, or color distortion.

[0004] On the other hand, the compact structure limits the use of large-diameter lenses, resulting in insufficient light intake. At the same time, the large differences in the incident angle of light within the narrow space lead to uneven illumination distribution within the field of view, with the edge brightness being significantly lower than the center, affecting the signal-to-noise ratio of image acquisition.

[0005] Thirdly, in industrial precision measurement applications, telecentric lenses are typically required to eliminate perspective errors. However, traditional short focal length designs are limited by physical length, making it difficult to construct a high-precision telecentric optical path while maintaining a large field of view, thus limiting measurement accuracy.

[0006] The disclosure of the above background technical content is only for the purpose of assisting in understanding the concept and technical solution of this application, and does not necessarily provide technical instruction. Summary of the Invention

[0007] The purpose of this invention is to provide a retro-telescopic optical lens that achieves low-distortion imaging quality on a lens with a focal length of approximately 12mm, thereby meeting the high-quality, wide-field-of-view imaging requirements of industrial inspection.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An optical lens comprising eight lenses of optical power, including a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially along the optical axis from the object plane to the image plane, wherein: The optical powers of the first to the eighth lenses are negative, negative, positive, positive, negative, positive, positive, positive, and positive, respectively. The first lens has a convex object-side surface near the optical axis and a concave image-side surface near the optical axis; the second lens has a concave image-side surface near the optical axis; the third and sixth lenses are biconvex mirrors; the fourth lens has a convex object-side surface near the optical axis and a concave image-side surface near the optical axis; the fifth lens is a biconcave mirror; the seventh lens and the eighth lens both have convex image-side and object-side surfaces near the optical axis. The optical axis distance from the image side of the second lens to the object side of the fourth lens is between 14.2 mm and 22.5 mm, and the center thickness of the third lens is between 2.1 mm and 3.5 mm. The optical lens satisfies: 10.5mm ≤ f ≤13mm, 4≤ TTL / f ≤5.5, where, f This refers to the entire focal length of the lens. TTL It is the distance on the optical axis from the vertex of the object side of the first lens to the imaging surface.

[0009] Furthermore, based on any one or a combination of the aforementioned technical solutions, the optical lens satisfies: 50mm ≤ TTL ≤58mm, 0.18≤ bfl / TTL ≤0.24, where, bfl This is the rear focal length of the lens.

[0010] Furthermore, following any one or a combination of the aforementioned technical solutions, among the lenses with positive optical power, the sixth lens has the highest optical power, with a focal length between 9.6mm and 12.5mm. The latter three lenses (the sixth, seventh, and eighth lenses) all have positive optical power, and the positive lens with the highest optical power among the eight lenses appears in this latter group of lenses. These three rear lenses are responsible for strongly converging the light, determining the relatively long effective focal length of the system.

[0011] Furthermore, following any or a combination of the aforementioned technical solutions, the optical axis distance from the object-side surface of the fifth lens to the image-side surface of the eighth lens is between 6.12 mm and 9.1 mm, and the optical axis distance from the image-side surface of the eighth lens to the imaging surface is between 10.2 mm and 14.6 mm. From these optical axis distance data, it can be seen that placing the positive lens with the highest optical power in a mid-to-rear position, and closely arranging it with the seventh and eighth lenses, forms a highly efficient rear-group convergence correction module, leaving space for filters and sensors, further contributing to miniaturization.

[0012] Furthermore, based on any or a combination of the aforementioned technical solutions, the center thickness of the seventh lens is between 1.4 mm and 2.35 mm, and the center thickness of the eighth lens is between 1.73 mm and 2.5 mm. The optical axis distance from the image side of the sixth lens to the object side of the seventh lens is between 0.02 mm and 0.25 mm, and the optical axis distance from the image side of the seventh lens to the object side of the eighth lens is between 0.05 mm and 0.25 mm.

[0013] Furthermore, based on any one or a combination of the aforementioned technical solutions, the focal length of each lens satisfies the following condition: -4 ≤ f 1 / f ≤-1.9, -4.1≤ f 2 / f ≤-1.35, 1.1≤ f 3 / f ≤2.75, 5≤ f 4 / f ≤12, -0.65≤ f 5 / f ≤-0.4, 0.7≤ f 6 / f ≤1.1, 1.6≤ f 7 / f ≤2.05, 1.6≤ f 8 / f ≤2.78, where, f 1 is the focal length of the first lens ，f 2 represents the focal length of the second lens. f 3 is the focal length of the third lens ，f 4 represents the focal length of the fourth lens. f 5 is the focal length of the fifth lens. f 6 represents the focal length of the sixth lens. f 7 is the focal length of the seventh lens. f 8 represents the focal length of the eighth lens.

[0014] Furthermore, based on any one or a combination of the aforementioned technical solutions, the radius of curvature of the fourth lens satisfies: 0.95 ≤ r 41 / r 42 ≤1.22, where, r 41 Let be the radius of curvature of the object-side surface of the fourth lens. r 42 Let be the radius of curvature of the image-side surface of the fourth lens; The radius of curvature of the eighth lens satisfies: 37 ≤ | r 82 / r 81 |≤50, where, r 81 Let be the radius of curvature of the object-side surface of the eighth lens. r 82 Let be the radius of curvature of the image-side surface of the eighth lens.

[0015] Furthermore, based on any one or a combination of the aforementioned technical solutions, the radius of curvature of the fifth lens satisfies: -7.6mm ≤ r 51 ≤-6.7mm, 16.2mm≤ r 52 ≤21mm, where, r 51 Let be the radius of curvature of the object-side surface of the fifth lens. r 52 Let be the radius of curvature of the image-side surface of the fifth lens.

[0016] Furthermore, following any one or a combination of the aforementioned technical solutions, the fifth lens and the sixth lens constitute a cemented lens, and the radius of curvature of the sixth lens satisfies: -10.8mm ≤ r 62 ≤-7.5mm, where, r 62 Let be the radius of curvature of the image-side surface of the sixth lens; And / or, the center thickness of the fifth lens is between 0.65 mm and 1.1 mm, the center thickness of the sixth lens is between 2.25 mm and 3.2 mm, and the optical axis distance from the image side of the fifth lens to the object side of the sixth lens is between 0 mm and 0.25 mm.

[0017] Furthermore, based on any one or a combination of the aforementioned technical solutions, the lens satisfies: 40°≤ Fov ≤49°, where, FovThe maximum field of view of the lens, combined with a field of view greater than 40°, defines the aforementioned short focal length lens with a retro-telephoto structure as also having a large field of view; And / or, 2≤ Fov / Y m / 2≤2.8, where, Fov The maximum field of view of the lens. Y m The image height corresponds to the maximum field of view, ensuring ideal distortion control and uniform illumination distribution; And / or, 21.5≤ Y 1×180 / pi ≤25.5, where, Y 1 represents the lens image height when the half-field of view is 1°. pi Pi; And / or, 0.04≤ Fov / (2× D 1) / TTL ≤0.055, where 2× D 1 is the effective diameter of the first lens. Fov This is the maximum field of view of the lens.

[0018] Furthermore, based on any one or a combination of the aforementioned technical solutions, the lens satisfies: 1.3≤2× D 1 / f ≤1.7, where 2× D 1 represents the effective diameter of the first lens; And / or, 0.85≤ bfl / f ≤1.3, where, bfl This is the rear focal length of the lens.

[0019] Furthermore, based on any one or a combination of the aforementioned technical solutions, the lens satisfies: 9.2mm≤ Y m ≤9.85mm, where, Y m The image height corresponding to the maximum field of view; And / or, 0.35mm≤ Y 1≤0.45mm, where, Y 1 represents the lens image height when the half-field angle is 1°; And / or, 15.5mm≤2× D 1≤18mm, where 2× D 1 represents the effective diameter of the first lens.

[0020] Furthermore, in accordance with any or a combination of the aforementioned technical solutions, the optical lens further includes an aperture stop disposed between the fourth lens and the fifth lens, wherein the optical axis distance between the aperture stop and the object side surface of the fifth lens is adjustable within the range of 2.5 mm to 4.8 mm; And / or, the optical lens further includes a filter disposed between the eighth lens and the imaging surface, wherein the optical axis distance between the image side of the eighth lens and the filter is adjustable in the range of 5.9 mm to 9.9 mm.

[0021] Furthermore, based on any one or a combination of the aforementioned technical solutions, all eight lenses with optical power are spherical mirrors.

[0022] Furthermore, based on any one or a combination of the aforementioned technical solutions, the optical lens satisfies: 12mm ≤ f ≤13mm.

[0023] According to another aspect of the present invention, a camera device is provided, including an electronic photosensitive element and an optical lens as described above.

[0024] According to another aspect of the present invention, an industrial inspection device is provided, including an image processor and a camera device as described above, wherein the camera device may be a line scan camera or an area scan camera.

[0025] The beneficial effects of the technical solution provided by this invention are as follows: it achieves a total length TTL of 50mm to 58mm for a lens with a focal length of about 12mm, balances physical length and distortion control, and meets the high-precision measurement needs of the industrial field. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the lens arrangement of the lens provided in the first embodiment of the present invention; Figure 2 The image shows the MTF frequency curve of the lens in the first embodiment of the present invention under infinite object distance. The horizontal axis represents the spatial frequency (in LP / mm), and the vertical axis represents the OTF modulus (dimensionless). Figure 3The image shows the MTF frequency curve of the lens in the first embodiment of the present invention at an object distance of 300mm. The horizontal axis represents the spatial frequency (in LP / mm), and the vertical axis represents the OTF modulus (dimensionless). Figure 4 The image shows the MTF frequency curve of the lens in the first embodiment of the present invention at an object distance of 100mm. The horizontal axis represents the spatial frequency (in LP / mm), and the vertical axis represents the OTF modulus (dimensionless). Figure 5 The image shows the relative illumination curve of the lens in the first embodiment of the present invention under infinite object distance. The horizontal axis represents the Y field of view (in mm), and the vertical axis represents the relative illumination (dimensionless). Figure 6 The image shows the relative illumination curve of the lens in the first embodiment of the present invention at an object distance of 300mm. The horizontal axis represents the Y field of view (in mm), and the vertical axis represents the relative illumination (dimensionless). Figure 7 The image shows the relative illumination curve of the lens in the first embodiment of the present invention at an object distance of 100mm. The horizontal axis represents the Y field of view (in mm), and the vertical axis represents the relative illumination (dimensionless). Figure 8 The distortion curve of the lens in the first embodiment of the present invention is shown when the object distance is infinite. The horizontal axis is the distortion percentage (in %), and the vertical axis is the normalized image height (dimensionless). Figure 9 The distortion curve of the lens in the first embodiment of the present invention is shown at an object distance of 300mm. The horizontal axis is the distortion percentage (in %), and the vertical axis is the normalized image height (dimensionless). Figure 10 The distortion curve of the lens in the first embodiment of the present invention is shown at an object distance of 100mm. The horizontal axis is the distortion percentage (in %), and the vertical axis is the normalized image height (dimensionless). Figure 11 This is a schematic diagram of the lens arrangement of a lens provided in the second embodiment of the present invention; Figure 12 The image shows the MTF frequency curve of the lens in the second embodiment of the present invention under infinite object distance. The horizontal axis represents the spatial frequency (in LP / mm), and the vertical axis represents the OTF modulus (dimensionless). Figure 13 The image shows the MTF frequency curve of the lens in the second embodiment of the present invention at an object distance of 300mm. The horizontal axis represents the spatial frequency (in LP / mm), and the vertical axis represents the OTF modulus (dimensionless). Figure 14The image shows the MTF frequency curve of the lens in the second embodiment of the present invention at an object distance of 100mm. The horizontal axis represents the spatial frequency (in LP / mm), and the vertical axis represents the OTF modulus (dimensionless). Figure 15 The image shows the relative illumination curve of the lens in the second embodiment of the present invention under infinite object distance. The horizontal axis represents the Y field of view (in mm), and the vertical axis represents the relative illumination (dimensionless). Figure 16 The image shows the relative illumination curve of the lens in the second embodiment of the present invention at an object distance of 300mm. The horizontal axis represents the Y field of view (in mm), and the vertical axis represents the relative illumination (dimensionless). Figure 17 The image shows the relative illumination curve of the lens in the second embodiment of the present invention at an object distance of 100mm. The horizontal axis represents the Y field of view (in mm), and the vertical axis represents the relative illumination (dimensionless). Figure 18 The distortion curve of the lens in the second embodiment of the present invention is shown when the object distance is infinite. The horizontal axis is the distortion percentage (in %), and the vertical axis is the normalized image height (dimensionless). Figure 19 The distortion curve of the lens in the second embodiment of the present invention is shown at an object distance of 300mm. The horizontal axis is the distortion percentage (in %), and the vertical axis is the normalized image height (dimensionless). Figure 20 The distortion curve of the lens in the second embodiment of the present invention is shown at an object distance of 100mm. The horizontal axis is the distortion percentage (in %), and the vertical axis is the normalized image height (dimensionless). Figure 21 This is a schematic diagram of the lens arrangement of a lens provided in the third embodiment of the present invention; Figure 22 The image shows the MTF frequency curve of the lens in the third embodiment of the present invention under infinite object distance. The horizontal axis represents the spatial frequency (in LP / mm), and the vertical axis represents the OTF modulus (dimensionless). Figure 23 The image shows the MTF frequency curve of the lens in the third embodiment of the present invention at an object distance of 300mm. The horizontal axis represents the spatial frequency (in LP / mm), and the vertical axis represents the OTF modulus (dimensionless). Figure 24 The image shows the MTF frequency curve of the lens in the third embodiment of the present invention at an object distance of 100mm. The horizontal axis represents the spatial frequency (in LP / mm), and the vertical axis represents the OTF modulus (dimensionless). Figure 25The image shows the relative illumination curve of the lens in the third embodiment of the present invention under infinite object distance. The horizontal axis represents the Y field of view (in mm), and the vertical axis represents the relative illumination (dimensionless). Figure 26 The image shows the relative illumination curve of the lens in the third embodiment of the present invention at an object distance of 300mm. The horizontal axis represents the Y field of view (in mm), and the vertical axis represents the relative illumination (dimensionless). Figure 27 The image shows the relative illumination curve of the lens in the third embodiment of the present invention at an object distance of 100mm. The horizontal axis represents the Y field of view (in mm), and the vertical axis represents the relative illumination (dimensionless). Figure 28 The distortion curve of the lens in the third embodiment of the present invention is shown when the object distance is infinite. The horizontal axis is the distortion percentage (in %), and the vertical axis is the normalized image height (dimensionless). Figure 29 The distortion curve of the lens in the third embodiment of the present invention is shown at an object distance of 300mm. The horizontal axis is the distortion percentage (in %), and the vertical axis is the normalized image height (dimensionless). Figure 30 The distortion curve of the lens in the third embodiment of the present invention is shown at an object distance of 100mm. The horizontal axis is the distortion percentage (in %), and the vertical axis is the normalized image height (dimensionless). Detailed Implementation

[0028] 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.

[0029] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data 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 a non-exclusive inclusion; for example, a process, method, apparatus, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0030] Lenses with a focal length of around 12mm produce small images of distant objects. Conventional designs typically use a telephoto structure with the positive group (positive optical power) lens elements in front, resulting in a relatively long overall length, which is not suitable for miniaturized devices. The present invention aims to provide an optical lens with a physically compressed focal length of around 12mm. It utilizes a specific anti-telephoto structure to achieve a short focal length and a large field of view. By using an anti-telephoto structure with the negative group (negative optical power) lens elements in front, combined with a tightly arranged rear group of lens elements, it can both strongly converge light and control the overall length of the lens.

[0031] See Figure 1 This is the lens arrangement of the first embodiment, where L1 represents the first lens, L2 represents the second lens, L3 represents the third lens, L4 represents the fourth lens, L5 represents the aperture stop, L6 represents the fifth lens, L7 represents the sixth lens, L8 represents the seventh lens, L9 represents the eighth lens, L10 represents the filter, and L11 represents the imaging surface. Lenses L1 to L9 are arranged sequentially from the object side to the image side. The aperture stop L5 is located on the image side of the fourth lens L4 and the object side of the fifth lens L6. The IR filter L10 is located between the eighth lens L9 and the imaging surface L11.

[0032] Figure 1 In the diagram, S1 represents the object-side surface of the first lens L1, S2 represents the image-side surface of the first lens L1; S3 represents the object-side surface of the second lens L2, S4 represents the image-side surface of the second lens L2; ​​S5 represents the object-side surface of the third lens L3, S6 represents the image-side surface of the third lens L3; S7 represents the object-side surface of the fourth lens L4, S8 represents the image-side surface of the fourth lens L4; S9 represents the surface of the aperture stop L5; S10 represents the object-side surface of the fifth lens L6, and S11 represents the image-side surface of the fifth lens L6. The side surface also refers to the object side surface of the sixth lens L7, which is cemented with the fifth lens L6; S12 refers to the image side surface of the sixth lens L7; S13 refers to the object side surface of the seventh lens L8; S14 refers to the image side surface of the seventh lens L8; S15 refers to the object side surface of the eighth lens L9; S16 refers to the image side surface of the eighth lens L9; S17 refers to the object side surface of the filter L10 (such as an IR filter); S18 refers to the image side surface of the filter L10; S19 refers to the surface where the imaging surface L11 is located.

[0033] The optical parameters in the following embodiments of the present invention include: Fov Indicates the maximum field of view of the lens. Y m Indicates correspondence Fov The image is tall, Y 1 indicates the image height of the lens when the half-field angle is 1°. TTL This indicates the total length of the lens, which in this embodiment is the distance along the optical axis from the vertex of the object-side surface of the first lens to the imaging surface L11, 2× D1 represents the effective diameter of the first lens. f 1 represents the focal length of the first lens. f 2 represents the focal length of the second lens. f 3 indicates the focal length of the third lens. f 4 represents the focal length of the fourth lens. f 5 indicates the focal length of the fifth lens. f 6 represents the focal length of the sixth lens. f 7 indicates the focal length of the seventh lens. f 8 represents the focal length of the eighth lens. f Indicates the entire focal length of the lens. bfl Indicates the rear focal length of the lens. pi Represents pi (π). r i1 Let represent the radius of curvature of the object-side surface of the i-th lens. r i2 Let be the radius of curvature of the image-side surface of the i-th lens. d Sm-Sn The distance between the optical axes of the surface with surface number Sm and the surface with surface number Sn (i, m, n are integers).

[0034] The lens in this embodiment is designed to achieve a maximum field of view of 46° or more, a total focal length of 12mm or more, and have qualified OTF modulus and relative illumination, while also exhibiting low distortion and low image distortion.

[0035] From an economic and cost perspective, all lenses from the first lens L1 to the eighth lens L9 can be made of spherical lenses, significantly reducing mold costs and manufacturing complexity. The curvature radius and center thickness of key lenses can be precisely defined to optimize aberration contributions. This invention does not limit each lens to using only spherical lenses.

[0036] First embodiment: Tables 1, 2, 3, and 4 show a first numerical embodiment of the optical lens according to the present invention, in conjunction with... Figures 1 to 10 To understand the first embodiment, Figure 1 The lens arrangement of the lens is shown in the following figure: From the object side to the image side, the following lenses are sequentially arranged: first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L6, sixth lens L7, seventh lens L8, and eighth lens L9. The concave / convex surface characteristics and optical power characteristics of each lens are as follows: The first lens L1 has negative optical power, its object side has a convex structure near the optical axis, and its image side has a concave structure near the optical axis. The second lens L2 is a biconcave mirror with negative optical power; The third lens L3 is a biconvex lens with positive optical power; The fourth lens L4 has positive optical power, its object side has a convex structure near the optical axis, and its image side has a concave structure near the optical axis. The fifth lens L6 is a double concave mirror with negative optical power, and the sixth lens L7 is a double convex mirror with positive optical power. The fifth lens L6 and the sixth lens L7 form a cemented lens, which makes the lens structure compact, reduces the number of light reflections between the lenses to reduce the loss of light energy, and lowers the misjudgment rate in the algorithm recognition process. The seventh lens, L8, is a biconvex lens with positive optical power; The eighth lens, L9, is a biconvex lens with positive optical power.

[0037] The aforementioned negative-negative-positive-positive-negative-positive-positive-positive optical power sequence, combined with a specific surface shape, achieves systematic correction of large field-of-view aberrations.

[0038] Besides the cemented lens achieving achromatic effect, the Abbe constants of the first to fourth lenses exhibit a series of values: low, high, low, and high. Specifically, the difference in Abbe constant between the first lens L1 and the second lens L2 is greater than 40, the difference between the third lens L3 and the second lens L2 is greater than 15, the difference between the third lens L3 and the fourth lens L4 is greater than 25, and the difference between the fifth lens L6 and the sixth lens L7 is greater than 30. The large difference in Abbe constant between adjacent lenses is beneficial for correcting chromatic aberration, improving image quality, reducing assembly sensitivity, and increasing image plane size. Therefore, the first lens L1 and the second lens L2 form an achromatic lens group, the third lens L3 forms an achromatic lens group with the second lens L2 and the fourth lens L4 respectively, and the fifth lens L6 and the sixth lens L7 form an achromatic lens group.

[0039] In this embodiment, the optical lens satisfies: 40°≤ Fov ≤44°, 9.25mm≤ Y m ≤9.8mm, 15.45mm≤2× D 1≤17.35mm, 0.416mm≤ Y 1≤0.442mm, 54mm≤ TTL ≤56mm, 11.6mm≤ f ≤12.8mm, 9.5mm≤ f 6≤10.5mm, 2.16° / mm≤ Fov / Y m / 2≤2.28° / mm,4.3≤ TTL / f ≤4.75, 0.2≤ bfl / TTL ≤0.28, 1.33≤2× D 1 / f ≤1.36, 24≤ Y 1×180 / pi ≤25.2, -2.9≤ f 1 / f ≤-2.2, -2.15≤ f 2 / f ≤-1.48, 1.28≤ f 3 / f ≤1.44, 10.65≤ f 4 / f ≤11.8, -0.57≤ f 5 / f ≤-0.48, 0.78≤ f 6 / f ≤0.88, 1.77≤ f 7 / f ≤1.98, 2.35≤ f 8 / f ≤2.65, 0.9≤ bfl / f ≤1.28, 0.043° / mm 2 ≤ Fov / (2× D 1) / TTL ≤0.051° / mm 2 1.06≤ r 41 / r 42 ≤1.18, 37≤| r 82 / r 81 |≤39,-7.3mm≤ r 51 ≤-6.7mm, 16.5mm≤ r 52 ≤17.5mm, -9.6mm≤ r 62 ≤-8.6mm; The optical axis distance from the image side of the second lens to the object side of the fourth lens d S4-S7 The thickness of the third lens is between 15.8 mm and 18 mm, and the center thickness is between 3 mm and 3.5 mm; the optical axis distance from the object-side surface of the fifth lens to the image-side surface of the eighth lens is... d S10-S16 The distance from the image-side surface of the eighth lens to the imaging surface is between 8.35 mm and 9.1 mm. d S16-S19 Between 12.2mm and 14.6mm; center thickness of the seventh lens d S13-S14 The center thickness of the eighth lens is between 1.95 mm and 2.35 mm. dS15-S16 Between 1.9 mm and 2.5 mm; the optical axis distance from the image-side surface of the sixth lens to the object-side surface of the seventh lens. d S12-S13 The optical axis distance between the image-side surface of the seventh lens and the object-side surface of the eighth lens is between 0.1 mm and 0.25 mm. d S14-S15 Between 0.1mm and 0.25mm; center thickness of the fifth lens d S10-S11 The center thickness of the sixth lens is between 0.9 mm and 1.1 mm. d S11-S12 Between 2.9mm and 3.15mm. It can be seen that the positive lens with the highest optical power (9.5mm ≤) f The lens (6≤10.5mm) is placed in the middle and rear position and closely arranged with the seventh and eighth lenses (with a spacing between them of 0.1mm to 0.25mm) to form a highly efficient rear convergence-correction module. This not only enhances the convergence capability to compress the length, but also facilitates centralized correction of advanced aberrations.

[0040] In a specific numerical embodiment, the optical parameters of each lens, aperture, and IR filter are shown in Tables 1 to 4: Table 1 Lens optical parameters of the first embodiment

[0041] In the table, a surface with an infinite radius of curvature indicates that its corresponding surface number represents a plane.

[0042] Among them, the distance D_1 between the aperture surface of surface number S9 and the object side of the fifth lens and the distance D_2 between the image side of the eighth lens of surface number S16 and the object side of the filter are variable distances. The variable distance D_1 has a variable range of 2.5mm to 4.1mm, and the variable distance D_2 has a variable range of 7.9mm to 9.85mm.

[0043] Taking object distances of infinity, 300mm, and 100mm as examples, the corresponding interval distances D_1 and D_2 are shown in Table 2: Table 2. Variable interval distances corresponding to the three object distances in the first embodiment.

[0044] The lens magnification is 0 when the object distance is infinity; 0.0390 when the object distance is 300mm; and 0.1061 when the object distance is 100mm.

[0045] Other optical parameters of the lens in this embodiment are shown in Table 3: Table 3 Other optical parameters of the lens at three object distances in the first embodiment

[0046] The optical parameter expressions of the lens in this embodiment are shown in Table 4: Table 4. Optical parameter expressions for the lens at three object distances in the first embodiment.

[0047] The table data in this embodiment uses rounding to obtain the calculated values.

[0048] The first lens L1 is a meniscus with a convex surface facing the object side, which is beneficial for collecting light and reducing distortion, thus improving image quality. The first lens L1 and the second lens L2 are negative power lenses, used to correct distortion and aberration caused by a large field of view, while also expanding the field of view. The image side of the second lens with negative power is concave, which is beneficial for receiving refracted light more smoothly, reducing aberration, lowering lens sensitivity, and also helping to reduce the lens aperture.

[0049] The object-side and image-side of the third lens are both convex, which is beneficial for correcting temperature drift. The third lens, L3, is the first lens with positive optical power from the object side, undertaking the main functions of focusing and imaging. As the optical power inflection point of the system, it is used to control the principal ray angle and image plane position. Furthermore, the object-side and image-side of the third lens L3 have large air gaps, which can adjust aberrations such as spherical aberration, coma, and field curvature, and disperse optical power, avoiding excessive burden on a single lens leading to higher-order aberrations. The compact layout of the fifth lens L6 to the eighth lens L9 compresses the length of the rear group, reduces interface reflections, controls stray light, ensures full-field imaging quality, and facilitates assembly and focusing, making it suitable for small equipment.

[0050] For a physical focal length of 10mm-13mm, the maximum field of view of a standard lens FOV Typically only 20° to 30°, this embodiment successfully decouples the strong correlation between focal length and field of view by using a retro-telescope design with a front group of negative optical power lenses for widening the field of view and a rear group of positive optical power lenses for focusing: the first and second lenses in the front group both have negative optical power and can receive light from a large angle (above 40°); the three rear lenses are all positive optical power lenses, and the positive lens with the highest optical power among the eight lenses appears in this rear group. These three rear group lenses are responsible for strongly converging the light, which determines the long effective focal length of the system; the third and fourth lenses with positive optical power and the fifth lens with a double concave structure are the middle group lenses, which are responsible for correcting the large number of aberrations (such as distortion, field curvature, etc.) caused by the conflict between the large field of view of the front group lenses and the rear group lenses, so that the overall lens physically achieves a field of view of more than 40° for a lens with a focal length of about 12mm, which can both ensure the shooting distance and avoid the field of view being too narrow.

[0051] like Figure 1 As shown, the aperture L5 is positioned between the fourth lens L4 and the fifth lens L6, which helps to increase the solid angle of the light rays projected onto the image plane and improve the illumination.

[0052] Among the positive lenses with optical power, the sixth lens has the highest optical power, with a focal length of 9.99mm. This embodies the design concept of strong convergence in the rear group: placing the positive lens with the highest optical power in the middle and rear position, and closely arranging it with the seventh and eighth lenses to form a highly efficient rear convergence correction module, leaving space for filters and sensors, further contributing to miniaturization; the first to fourth lenses L4 of the front group are responsible for pressing the edge light rays of the large field of view towards the center, reducing the angle of incidence; the aperture controls the aperture and field of view; the sixth lens L7, as the first strong positive lens in the rear group, has a short focal length that allows it to converge light onto the image plane with extremely high efficiency within a limited total length ( TTL / f Within approximately 4.5 (the length is reduced by using a strong convergence post-positioning), the total length is shortened.

[0053] The compact, wide-field-of-view lens design with front lens correction and rear lens strong convergence in this embodiment can integrate the lens and electronic image sensor into a camera device (line scan camera or area scan camera) for application in industrial inspection equipment (such as automated optical inspection equipment).

[0054] Based on a lens resolution of 166LP / mm, Figures 2 to 4 The images show the MTF (Modulation Transfer Function) frequency curves of the lens in the first embodiment above at three different object distances: infinite, 300mm, and 100mm. The horizontal axis represents spatial frequency in line pairs per millimeter (LP / mm), and the vertical axis represents the OTF modulus (a dimensionless, normalized value). Figure 2 It can be seen that, in millimeters, TS 0.0000 (mm) represents a central field-of-view OTF modulus of approximately 54%, while TS 2.3750 (mm) represents a non-central field-of-view (0.5 field of view) OTF modulus of approximately 51%. From... Figure 3 It can be seen that, in millimeters, TS0.0000 (mm) represents a central field-of-view OTF modulus of approximately 55%, while TS 4.7500 (mm) represents an edge field-of-view OTF modulus of approximately 41%. From... Figure 4 As can be seen, in millimeters, TS 0.0000 (mm) represents a center field of view OTF modulus of approximately 54%, and TS 4.7500 (mm) represents an edge field of view OTF modulus of approximately 42%, indicating that the lens can produce clear images.

[0055] Figures 5 to 7The images show the relative illumination curves of the lens in the first embodiment above under three conditions: infinite object distance, 300mm, and 100mm. The relative illumination diagram reflects the uniformity of illumination on the image. The horizontal axis represents the Y-field of view in millimeters (mm), and the vertical axis represents the relative illumination (a dimensionless, normalized value). Figure 5 It can be seen that the optical lens in this specific embodiment has a relative illumination greater than 75% corresponding to a Y-field of view of approximately 4.75mm, reflecting that the lens has high relative illumination and sufficient light intake. From Figure 6 It can be seen that the relative illumination corresponding to a Y-field of view of approximately 4.75mm is about 80%, reflecting that this lens has high relative illumination and sufficient light intake. From Figure 7 As can be seen, the relative illumination corresponding to a Y field of view of approximately 4.75mm is greater than 80%, reflecting that the lens has a high relative illumination and sufficient light intake, ensuring that even when the lens is used in relatively dark environments, there will be no vignetting at the edges of the actual image.

[0056] Figures 8 to 10 The images show the distortion of the lens in the first embodiment above at three different object distances: infinity, 300mm, and 100mm. Distortion is a principal ray aberration, reflecting the similarity of the image. The horizontal axis represents the distortion percentage (in %), and the vertical axis represents the normalized image height (dimensionless). Figure 8 The maximum distortion is approximately 0.55%. Figure 9 The maximum distortion is approximately -0.25%. Figure 10 The maximum distortion is approximately -1.1%, meaning that the optical lens in this embodiment has relatively small distortion and low image distortion.

[0057] Second embodiment: Tables 5, 6, 7, and 8 show a second numerical embodiment of the optical lens according to the present invention, in conjunction with... Figures 11 to 20 To understand the second embodiment, the lens arrangement of the lens is as follows: Figure 11 As shown, compared with the first embodiment, the positive and negative optical power characteristics of the lens remain unchanged. The difference in lens surface shape is that the object side of the second lens L2 in the second embodiment is convex, the object side of the seventh lens L8 is concave, and the image side of the eighth lens L9 is concave.

[0058] The Abbe constants of the first to the third lenses are low, high, and low, respectively. The difference in the Abbe constant values ​​of adjacent lenses is greater than 25. Therefore, the second lens L2, together with the first lens L1 and the third lens L3, forms an achromatic lens group. Similarly, the fifth lens L6, together with the fourth lens L4 and the sixth lens L7, forms an achromatic lens group.

[0059] In this embodiment, the optical lens satisfies: 42°≤ Fov ≤45°, 9.25mm≤ Ym ≤9.8mm,15.45mm≤2× D 1≤17.35mm,0.416mm≤ Y 1≤0.442mm,51mm≤ TTL ≤53.8mm,11.75mm≤ f ≤12.6mm,10.9mm≤ f 6≤12.5mm,2.22° / mm≤ Fov / Y m / 2≤2.29° / mm,4.1≤ TTL / f ≤4.55,0.2≤ bfl / TTL ≤0.26,1.33≤2× D 1 / f ≤1.6,24≤ Y 1×180 / pi ≤25.2,-2.9≤ f 1 / f ≤-2.1,-2.99≤ f 2 / f ≤-2.6,1.28≤ f 3 / f ≤1.55,7.5≤ f 4 / f ≤8,-0.54≤ f 5 / f ≤-0.47,0.93≤ f 6 / f ≤1.02,1.66≤ f 7 / f ≤1.94,1.6≤ f 8 / f ≤1.98,0.8≤ bfl / f ≤1.22,0.045° / mm 2 ≤ Fov / (2× D 1) / TTL ≤0.056° / mm 2 ,0.97≤ r 41 / r 42 ≤1.18,42≤| r 82 / r 81 |≤50,-7.6mm≤ r 51 ≤-6.9mm,17.5mm≤ r 52 ≤20.9mm,-10.7mm≤ r62 ≤-8.7mm; The optical axis distance from the image side of the second lens to the object side of the fourth lens d S4-S7 The thickness of the third lens is between 14.2 mm and 15.6 mm, and the center thickness is between 2.3 mm and 2.9 mm; the optical axis distance from the object side of the fifth lens to the image side of the eighth lens is... d S10-S16 The distance from the image-side surface of the eighth lens to the imaging surface is between 6.22 mm and 8.2 mm. d S16-S19 Between 11mm and 13.6mm; center thickness of the seventh lens d S13-S14 The center thickness of the eighth lens is between 1.4 mm and 1.85 mm. d S15-S16 Between 1.8 mm and 2.4 mm; the optical axis distance from the image-side surface of the sixth lens to the object-side surface of the seventh lens. d S12-S13 The optical axis distance between the image-side surface of the seventh lens and the object-side surface of the eighth lens is between 0.05 mm and 0.15 mm. d S14-S15 Between 0.05mm and 0.15mm; center thickness of the fifth lens d S10-S11 The center thickness of the sixth lens is between 0.65 mm and 0.95 mm. d S11-S12 Between 2.35mm and 2.7mm.

[0060] In a specific numerical embodiment, the optical parameters of each lens, aperture, and IR filter are shown in Tables 5 to 8: Table 5 Lens optical parameters of the second embodiment

[0061] In the table, a surface with an infinite radius of curvature indicates that its corresponding surface number represents a plane.

[0062] Among them, the distance D_1 between the aperture surface of surface number S9 and the object side of the fifth lens and the distance D_2 between the image side of the eighth lens of surface number S16 and the object side of the filter are variable distances. The variable distance D_1 has a variable range of 3.6mm to 4.8mm, and the variable distance D_2 has a variable range of 6.6mm to 8.8mm.

[0063] Taking object distances of infinity, 300mm, and 100mm as examples, the corresponding interval distances D_1 and D_2 are shown in Table 6: Table 6. Variable Interval Distances Corresponding to the Three Object Distances in the Second Embodiment

[0064] The lens magnification is 0 when the object distance is infinity; 0.0379 when the object distance is 300mm; and 0.1031 when the object distance is 100mm.

[0065] Other optical parameters of the lens in this embodiment are shown in Table 7: Table 7 Other optical parameters of the lens at three object distances in the second embodiment

[0066] The optical parameter expressions of the lens in this embodiment are shown in Table 8: Table 8. Optical parameter expressions for the lens at three object distances in the second embodiment.

[0067] The table data in this embodiment uses rounding to obtain the calculated values.

[0068] Based on a lens resolution of 166LP / mm, Figures 12 to 14 The images show the MTF (Modulation Transfer Function) frequency curves of the lens in the second embodiment above at three different object distances: infinite, 300mm, and 100mm. The horizontal axis represents spatial frequency in line pairs per millimeter (LP / mm), and the vertical axis represents the OTF modulus (a dimensionless, normalized value). Figure 12 It can be seen that, in millimeters, TS 0.0000 (mm) represents a central field-of-view OTF modulus of approximately 58%, while TS 2.3750 (mm) represents a non-central field-of-view (0.5 field of view) OTF modulus of approximately 50%. From... Figure 13 It can be seen that, in millimeters, TS 0.0000 (mm) represents a central field-of-view OTF modulus greater than 50%, while TS 4.7500 (mm) represents an edge field-of-view OTF modulus of approximately 42%. From... Figure 14 As can be seen, in millimeters, TS 0.0000 (mm) represents a center field of view OTF modulus of approximately 58%, and TS 4.7500 (mm) represents an edge field of view OTF modulus of approximately 42%, indicating that the lens can produce clear images.

[0069] Figures 15 to 17The images show the relative illumination curves of the lens in the second embodiment above under three conditions: infinite object distance, 300mm, and 100mm. The relative illumination diagram reflects the uniformity of illumination on the image. The horizontal axis represents the Y-field of view in millimeters (mm), and the vertical axis represents the relative illumination (dimensionless, normalized value). Figure 15 It can be seen that the optical lens in this specific embodiment has a relative illumination greater than 85% corresponding to a Y-field of view of approximately 4.75mm, reflecting that the lens has high relative illumination and sufficient light intake. From Figure 16 It can be seen that the relative illumination corresponding to a Y-field of view of approximately 4.75mm is about 88%, indicating that the lens has high relative illumination and sufficient light intake. From Figure 17 As can be seen, the relative illumination corresponding to a Y field of view of approximately 4.75mm is greater than 90%, reflecting that the lens has a high relative illumination and sufficient light intake, ensuring that even when the lens is used in relatively dark environments, there will be no vignetting at the edges of the actual image.

[0070] Figures 18 to 20 The images show the distortion of the lens in the second embodiment above at three different object distances: infinity, 300mm, and 100mm. Distortion is a principal ray aberration, reflecting the similarity of the image. The horizontal axis represents the distortion percentage (in %), and the vertical axis represents the normalized image height (dimensionless). Figure 18 The maximum distortion is approximately -1%. Figure 19 The maximum distortion is approximately -1.55%. Figure 20 The maximum distortion is approximately -2.32%, meaning that the optical lens in this embodiment has relatively small distortion and low image distortion.

[0071] Third embodiment: Tables 9, 10, 11, and 12 show a third numerical embodiment of the optical lens according to the present invention, in conjunction with... Figures 21 to 30 To understand the third embodiment, the lens arrangement of the lens is as follows: Figure 21 As shown, compared with the first embodiment, the positive and negative optical power characteristics of the lens remain unchanged. The difference in lens surface shape is that the object side of the second lens L2 in the third embodiment is convex, and the image side of the eighth lens L9 is concave.

[0072] The Abbe constants of the first to the third lenses are high, low, and high, respectively. The difference in the Abbe constant values ​​of adjacent lenses is greater than 23. Therefore, the second lens L2 forms an achromatic lens group with the first lens L1 and the third lens L3, respectively. Similarly, the fifth lens L6 forms an achromatic lens group with the fourth lens L4 and the sixth lens L7, respectively. The seventh lens L8 forms an achromatic lens group with the sixth lens L7 and the eighth lens L9, respectively.

[0073] In this embodiment, the optical lens satisfies: 45.5° ≤ Fov≤48°,9.25mm≤ Y m ≤9.8mm,16.2mm≤2× D 1≤17.9mm,0.36mm≤ Y 1≤0.42mm,54mm≤ TTL ≤57.6mm,10.5mm≤ f ≤11.6mm,9.9mm≤ f 6≤10.85mm,2.35° / mm≤ Fov / Y m / 2≤2.56° / mm,4.68≤ TTL / f ≤5.35,0.18≤ bfl / TTL ≤0.24,1.53≤2× D 1 / f ≤1.57,22.1≤ Y 1×180 / pi ≤22.5,-3.8≤ f 1 / f ≤-3.15,-3.99≤ f 2 / f ≤-2.3,2.15≤ f 3 / f ≤2.85,5.2≤ f 4 / f ≤7.35,-0.6≤ f 5 / f ≤-0.52,0.88≤ f 6 / f ≤1,1.66≤ f 7 / f ≤1.9,2.35≤ f 8 / f ≤2.83,0.85≤ bfl / f ≤1.21,0.045° / mm 2 ≤ Fov / (2× D 1) / TTL ≤0.053° / mm 2 ,0.99≤ r 41 / r 42 ≤1.2,38≤| r 82 / r 81 |≤46,-7.5mm≤ r 51 ≤-6.7mm,18.5mm≤ r 52≤20.5mm, -9.5mm≤ r 62 ≤-7.6mm; The optical axis distance from the image side of the second lens to the object side of the fourth lens d S4-S7 The thickness of the third lens is between 18mm and 22.5mm, and the center thickness is between 2.1mm and 2.8mm; the optical axis distance from the object-side surface of the fifth lens to the image-side surface of the eighth lens is... d S10-S16 The distance from the image-side surface of the eighth lens to the imaging surface is between 6.12 mm and 8.2 mm. d S16-S19 Between 10mm and 12.8mm; center thickness of the seventh lens d S13-S14 The center thickness of the eighth lens is between 1.4 mm and 1.65 mm. d S15-S16 Between 1.7 mm and 1.99 mm; the optical axis distance from the image-side surface of the sixth lens to the object-side surface of the seventh lens. d S12-S13 The optical axis distance between the image-side surface of the seventh lens and the object-side surface of the eighth lens is between 0.05 mm and 0.15 mm. d S14-S15 Between 0.05mm and 0.15mm; center thickness of the fifth lens d S10-S11 The center thickness of the sixth lens is between 0.7 mm and 0.9 mm. d S11-S12 Between 2.5mm and 3.1mm.

[0074] In a specific numerical embodiment, the optical parameters of each lens, aperture, and IR filter are shown in Tables 9 to 12: Table 9 Lens optical parameters of the third embodiment

[0075] In the table, a surface with an infinite radius of curvature indicates that its corresponding surface number represents a plane.

[0076] Among them, the distance D_1 between the aperture surface of surface number S9 and the object side of the fifth lens and the distance D_2 between the image side of the eighth lens of surface number S16 and the object side of the filter are variable distances. The variable distance D_1 has a variable range of 3.3mm to 4.8mm, and the variable distance D_2 has a variable range of 5.9mm to 7.9mm.

[0077] Taking object distances of infinity, 300mm, and 100mm as examples, the corresponding interval distances D_1 and D_2 are shown in Table 10: Table 10 Variable Interval Distance Table Corresponding to Three Object Distances in the Third Embodiment

[0078] The lens magnification is 0 when the object distance is infinity; 0.0348 when the object distance is 300mm; and 0.0951 when the object distance is 100mm.

[0079] Other optical parameters of the lens in this embodiment are shown in Table 11: Table 11 Other optical parameters of the lens at three object distances in the third embodiment

[0080] The optical parameter expressions of the lens in this embodiment are shown in Table 12: Table 12 Optical parameter expressions for the lens at three object distances in the third embodiment

[0081] The table data in this embodiment uses rounding to obtain the calculated values.

[0082] Based on a lens resolution of 166LP / mm, Figures 22 to 24 The images show the MTF (Modulation Transfer Function) frequency curves of the lens in the third embodiment above at three different object distances: infinite, 300mm, and 100mm. The horizontal axis represents spatial frequency in line pairs per millimeter (LP / mm), and the vertical axis represents the OTF modulus (a dimensionless, normalized value). Figure 22 It can be seen that, in millimeters, TS 0.0000 (mm) represents a central field-of-view OTF modulus of approximately 56%, while TS 4.2750 (mm) represents a non-central field-of-view (0.9 field of view) OTF modulus of approximately 40%. From... Figure 23 It can be seen that, in millimeters, TS 0.0000 (mm) represents a central field-of-view OTF modulus of approximately 61%, while TS 4.7500 (mm) represents a peripheral field-of-view OTF modulus of approximately 40%. From... Figure 24 As can be seen, in millimeters, TS 0.0000 (mm) represents a center field of view OTF modulus of approximately 61%, and TS 4.7500 (mm) represents an edge field of view OTF modulus of approximately 42%, indicating that the lens can produce clear images.

[0083] Figures 25 to 27The images above show the relative illumination curves of the lens in the third embodiment for three conditions: infinite object distance, 300mm, and 100mm. The relative illumination diagram reflects the uniformity of illumination on the image. The horizontal axis represents the Y-field of view in millimeters (mm), and the vertical axis represents the relative illumination (dimensionless, normalized value). Figure 25 It can be seen that the optical lens in this specific embodiment has a relative illumination greater than 92% corresponding to a Y-field of view of approximately 4.75mm, reflecting that the lens has high relative illumination and sufficient light intake. From Figure 26 It can be seen that the relative illumination corresponding to a Y-field of view of approximately 4.75mm is about 95%, reflecting that this lens has high relative illumination and sufficient light intake. From Figure 27 As can be seen, the relative illumination corresponding to a Y field of view of approximately 4.75mm is greater than 96%, reflecting that the lens has a high relative illumination and sufficient light intake, ensuring that even when the lens is used in relatively dark environments, there will be no vignetting at the edges of the actual image.

[0084] Figures 28 to 30 The images show the distortion of the lens in the third embodiment above at three different object distances: infinity, 300mm, and 100mm. Distortion is a principal ray aberration, reflecting the similarity of the image. The horizontal axis represents the distortion percentage (in %), and the vertical axis represents the normalized image height (dimensionless). Figure 28 The maximum distortion is approximately -1%. Figure 29 The maximum distortion is approximately -1.5%. Figure 30 The maximum distortion is approximately -2.15%, meaning that the optical lens in this embodiment has relatively small distortion and low image distortion.

[0085] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0086] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. An optical lens comprising eight lenses of optical power, including a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially along the optical axis from the object plane to the image plane, characterized in that: The optical powers of the first to the eighth lenses are negative, negative, positive, positive, negative, positive, positive, positive, and positive, respectively. The first lens has a convex object-side surface near the optical axis and a concave image-side surface near the optical axis; the second lens has a concave image-side surface near the optical axis; the third and sixth lenses are biconvex mirrors; the fourth lens has a convex object-side surface near the optical axis and a concave image-side surface near the optical axis; the fifth lens is a biconcave mirror; the seventh lens and the eighth lens both have convex image-side and object-side surfaces near the optical axis. The optical axis distance from the image side of the second lens to the object side of the fourth lens is between 14.2 mm and 22.5 mm, and the center thickness of the third lens is between 2.1 mm and 3.5 mm. The optical lens satisfies: 10.5mm ≤ f ≤13mm, 4≤ TTL / f ≤5.5, where, f This refers to the entire focal length of the lens. TTL The distance on the optical axis is from the vertex of the object side of the first lens to the imaging surface; The focal length of each lens satisfies the following condition: -4≤ f 1 / f ≤-1.9, -4.1≤ f 2 / f ≤-1.35, 1.1≤ f 3 / f ≤2.75, 5≤ f 4 / f ≤12, -0.65≤ f 5 / f ≤-0.4, 0.7≤ f 6 / f ≤1.1, 1.6≤ f 7 / f ≤2.05, 1.6≤ f 8 / f ≤2.78, where, f 1 is the focal length of the first lens ，f 2 represents the focal length of the second lens. f 3 is the focal length of the third lens ，f 4 represents the focal length of the fourth lens. f 5 is the focal length of the fifth lens. f 6 is the focal length of the sixth lens. f 7 represents the focal length of the seventh lens. f 8 represents the focal length of the eighth lens.

2. The optical lens according to claim 1, characterized in that, The optical axis distance from the object side of the fifth lens to the image side of the eighth lens is between 6.12 mm and 9.1 mm, and the optical axis distance from the image side of the eighth lens to the imaging surface is between 10.2 mm and 14.6 mm.

3. The optical lens according to claim 1, characterized in that, The optical lens meets the following requirement: 50mm≤ TTL ≤58mm, 0.18≤ bfl / TTL ≤0.24, where, bfl This is the rear focal length of the lens.

4. The optical lens according to claim 1, characterized in that, Among the eight lenses with optical power, the sixth lens is the positive lens with the highest optical power, and its focal length is between 9.6 mm and 12.5 mm.

5. The optical lens according to claim 1, characterized in that, The center thickness of the seventh lens is between 1.4 mm and 2.35 mm, and the center thickness of the eighth lens is between 1.73 mm and 2.5 mm. The optical axis distance from the image side of the sixth lens to the object side of the seventh lens is between 0.02 mm and 0.25 mm, and the optical axis distance from the image side of the seventh lens to the object side of the eighth lens is between 0.05 mm and 0.25 mm.

6. The optical lens according to claim 1, characterized in that, The radius of curvature of the fourth lens satisfies: 0.95 ≤ r 41 / r 42 ≤1.22, where, r 41 Let be the radius of curvature of the object-side surface of the fourth lens. r 42 Let be the radius of curvature of the image-side surface of the fourth lens; The radius of curvature of the eighth lens satisfies: 37 ≤ | r 82 / r 81 |≤50, where, r 81 Let be the radius of curvature of the object-side surface of the eighth lens. r 82 Let be the radius of curvature of the image-side surface of the eighth lens.

7. The optical lens according to claim 1, characterized in that, The radius of curvature of the fifth lens satisfies: -7.6mm≤ r 51 ≤-6.7mm, 16.2mm≤ r 52 ≤21mm, where, r 51 Let be the radius of curvature of the object-side surface of the fifth lens. r 52 Let be the radius of curvature of the image-side surface of the fifth lens.

8. The optical lens according to claim 7, characterized in that, The fifth lens and the sixth lens constitute a cemented lens, and the radius of curvature of the sixth lens satisfies: -10.8mm ≤ r 62 ≤-7.5mm, where, r 62 Let be the radius of curvature of the image-side surface of the sixth lens; And / or, the center thickness of the fifth lens is between 0.65 mm and 1.1 mm, the center thickness of the sixth lens is between 2.25 mm and 3.2 mm, and the optical axis distance from the image side of the fifth lens to the object side of the sixth lens is between 0 mm and 0.25 mm.

9. The optical lens according to claim 1, characterized in that, The lens satisfies: 40°≤ Fov ≤49°, where, Fov This is the maximum field of view of the lens; And / or, 2≤ Fov / Y m / 2≤2.8, where, Y m The image height corresponding to the maximum field of view. Fov This is the maximum field of view of the lens; And / or, 21.5≤ Y 1×180 / pi ≤25.5, where, Y 1 represents the lens image height when the half-field of view is 1°. pi Pi; And / or, 0.04≤ Fov / (2× D 1) / TTL ≤0.055, where, Fov The maximum field of view of the lens, 2× D 1 represents the effective diameter of the first lens.

10. The optical lens according to claim 1, characterized in that, The lens satisfies: 1.3≤2× D 1 / f ≤1.7, where 2× D 1 represents the effective diameter of the first lens; And / or, 0.85≤ bfl / f ≤1.3, where, bfl This is the rear focal length of the lens.

11. The optical lens according to claim 1, characterized in that, The lens satisfies: 9.2mm≤ Y m ≤9.85mm, where, Y m The image height corresponding to the maximum field of view; And / or, 0.35mm≤ Y 1≤0.45mm, where, Y 1 represents the lens image height when the half-field angle is 1°; And / or, 15.5mm≤2× D 1≤18mm, where 2× D 1 represents the effective diameter of the first lens.

12. The optical lens according to claim 1, characterized in that, The optical lens also includes an aperture stop disposed between the fourth lens and the fifth lens, and the optical axis distance between the aperture stop and the object side surface of the fifth lens is adjustable in the range of 2.5mm to 4.8mm; And / or, the optical lens further includes a filter disposed between the eighth lens and the imaging surface, wherein the optical axis distance between the image side of the eighth lens and the filter is adjustable in the range of 5.9 mm to 9.9 mm.

13. The optical lens according to any one of claims 1 to 12, characterized in that, All eight lenses with optical power are spherical mirrors.

14. The optical lens according to any one of claims 1 to 12, characterized in that, The optical lens satisfies: 12mm≤ f ≤13mm.

15. A camera device, characterized in that, It includes electronic photosensitive elements and optical lenses as described in any one of claims 1 to 14.

16. An industrial testing device, characterized in that, It includes an image processor and a camera device as described in claim 15.

Images