Optical lens, camera device and industrial detection equipment with both long-distance and edge image quality

Abstract

The application discloses an optical lens considering both telescopic ability and edge image quality, a camera device and industrial detection equipment with the same. Eight lenses with focal lengths of negative-positive-positive-negative-negative-positive-positive-negative are arranged along the optical axis from the object plane to the image plane. The object side of the first lens is a convex surface, and the image side is a concave surface structure. The second lens, the third lens and the seventh lens are all double convex lenses. The fourth lens is a double concave lens. The object side of the fifth lens is a concave surface structure, and the image side is a convex surface structure. The image side of the sixth lens is a convex surface structure. The object side of the eighth lens is a concave surface structure. The total focal length of the lens is between 14.5 mm and 17 mm, the maximum field of view is between 30° and 38°, and the ratio of the total length of the lens to the total focal length is between 2.5 and 3. The balance between the telescopic resolution and the edge image quality is realized under the compact size.

Description

Technical Field

[0001] This invention relates to the field of optics, and more particularly to an optical lens, a camera device, and an industrial inspection device that combines telescopic capability with edge image quality. Background Technology

[0002] In the design of medium telephoto / medium telephoto lenses, compared with ultra-wide-angle lenses, lenses with a field of view in the range of 30° to 40° have a better sense of telephoto. These lenses usually sacrifice edge image quality in order to pursue telephoto capabilities.

[0003] On the one hand, in order to reduce the total length ( TTL Conventional designs often rely excessively on the strong optical power of the front negative lens to compress the beam, which results in an excessively large chief ray angle (CRA) in the edge field of view, causing severe astigmatism and field curvature, and a sharp drop in image edge resolution.

[0004] On the other hand, pincushion distortion is the main problem in narrow field of view. If the distortion is forcibly corrected in a conventional structure, it will often exacerbate the astigmatism at the edges.

[0005] Thirdly, conventional lenses typically require a longer back focal length (BFL) to smooth out the angle of incidence of light rays at the edges in order to achieve good edge image quality. This directly leads to... TTL / f A high ratio (often exceeding 3.2) contradicts the urgent need for miniaturization in modern devices. Forcibly compressing the overall length will inevitably lead to uncontrolled edge aberrations, failing to meet the edge resolution requirements of high-pixel sensors (such as 48MP, 64MP).

[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 an optical lens that balances telephoto capability and edge image quality, thus solving the problem of balancing telephoto resolution and edge image quality.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An optical lens that balances telephoto capability and edge image quality comprises eight lenses with 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 object side of the first lens has a convex structure near the optical axis, and its image side has a concave structure near the optical axis. The first lens also has negative optical power. The object-side and image-side surfaces of the second, third, and seventh lenses are all convex near the optical axis; The object-side and image-side surfaces of the fourth lens are both concave near the optical axis. The object side of the fifth lens has a concave structure near the optical axis, and its image side has a convex structure near the optical axis. The fifth lens also has negative optical power. The image-side surface of the sixth lens is convex near the optical axis, and the sixth lens has positive optical power. The object side of the eighth lens has a concave structure near the optical axis, and the eighth lens has negative optical power. The optical lens satisfies: 14.5mm ≤ f ≤17mm, 30°≤ Fov ≤38°, and 2.5≤ TTL / f ≤3, where, f This refers to the entire focal length of the lens. Fov The maximum field of view 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 axis distance from the image side of the first lens to the object side of the second lens is between 7.1 mm and 10.25 mm. The center thickness of the second lens is between 2.3 mm and 3.4 mm, the center thickness of the third lens is between 3.8 mm and 5.5 mm, and the center thickness of the fourth lens is between 1.2 mm and 2.95 mm. The optical axis distance from the object side of the second lens to the image side of the fourth lens is between 8.5 mm and 11.5 mm.

[0010] Furthermore, based on any or a combination of the aforementioned technical solutions, the optical axis distance from the image side of the fourth lens to the object side of the fifth lens is between 4.8 mm and 8.8 mm. The center thickness of the fifth lens is between 1 mm and 2.75 mm, the center thickness of the sixth lens is between 1.3 mm and 2.4 mm, the center thickness of the seventh lens is between 1.75 mm and 3.5 mm, and the center thickness of the eighth lens is between 0.7 mm and 1.2 mm. The optical axis distance from the object side of the fifth lens to the image side of the eighth lens is between 6.7 mm and 8.2 mm, and the optical axis distance from the image side of the eighth lens to the imaging surface is between 9.7 mm and 12.9 mm.

[0011] Furthermore, based on any one or a combination of the aforementioned technical solutions, the optical lens satisfies: 43mm ≤ TTL ≤47mm; 0.044≤ Fov / (2× D 1) / TTL ≤0.062; 0.18≤ bfl / TTL ≤0.32; 0.196≤ Y m / TTL ≤0.225; where, 2× D 1 is the effective diameter of the first lens. Fov The maximum field of view of the lens. bfl The rear focal length of the lens. Y m This represents the image height corresponding to the maximum field of view.

[0012] Furthermore, based on any one or a combination of the aforementioned technical solutions, the focal length of the positive lens with the highest optical power is between 8.8 mm and 11 mm. Among the eight lenses with optical power, the positive lens with the highest optical power is either the seventh lens or the third lens.

[0013] Furthermore, based on any one or a combination of the aforementioned technical solutions, the lens satisfies: 1.68≤ Fov / Y m / 2≤1.84, where, Y m The image height corresponding to the maximum field of view; And / or, 30≤ Y 1×180 / pi ≤34, where, Y 1 represents the lens image height when the half-field of view is 1°. pi Pi; And / or, 0.76≤2× D 1 / f ≤0.99, where 2× D 1 represents the effective diameter of the first lens; And / or, 0.55≤ bfl / f ≤0.88, where, bfl This is the rear focal length of the lens.

[0014] Furthermore, following any one or a combination of the aforementioned technical solutions, the third lens and the fourth lens constitute a cemented lens, wherein the radius of curvature of the cemented surface satisfies: -16.1mm ≤ r32 ≤-11.3mm, where, r 32 Let be the radius of curvature of the image-side surface of the third lens; And / or, the seventh lens and the eighth lens constitute a cemented lens, and the radius of curvature of their cemented surface satisfies: -22mm ≤ r 72 ≤-8.5mm, where, r 72 Let be the radius of curvature of the image-side surface of the seventh lens.

[0015] Furthermore, based on any one or a combination of the aforementioned technical solutions, the radius of curvature of the fifth lens satisfies: -5.6mm ≤ r 51 ≤-4.45mm, -8mm≤ r 52 ≤-6.5mm, 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; The optical axis distance between the image side of the fifth lens and the object side of the sixth lens is between 0.01 mm and 0.3 mm.

[0016] Furthermore, based on any one or a combination of the aforementioned technical solutions, among the eight lenses with optical power, the lens with the largest central thickness is the third lens, whose central thickness is between 3.75 mm and 5.2 mm. Among the eight lenses with optical power, the lens with the smallest center thickness is the eighth lens, with a center thickness ranging from 0.7 mm to 1.15 mm.

[0017] Furthermore, based on any one or a combination of the aforementioned technical solutions, the lens satisfies: 9.2mm≤ Y m ≤9.8mm, of which, Y m The image height corresponding to the maximum field of view; And / or, 0.5mm≤ Y 1≤0.63mm, where, Y 1 represents the lens image height when the half-field angle is 1°; And / or, 12.1mm≤2× D 1≤15.3mm, where 2× D 1 represents the effective diameter of the first lens.

[0018] Furthermore, based on any one or a combination of the aforementioned technical solutions, all eight lenses with optical power are spherical mirrors.

[0019] Furthermore, based on any one or a combination of the aforementioned technical solutions, the refractive index of the eight-element lens with optical power is between 1.5 and 2.035, wherein the difference between the maximum and minimum refractive index is between 0.05 and 0.48.

[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 5.9 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 mm to 8.5 mm.

[0021] Furthermore, following any one or a combination of the aforementioned technical solutions, the focal length of each lens satisfies the following condition: -1.68 ≤ f 1 / f ≤-1.17, 0.88≤ f 2 / f ≤1.11, 0.56≤ f 3 / f ≤0.72, -0.44≤ f 4 / f ≤-0.32, -3.6≤ f 5 / f ≤-1.65, 0.99≤ f 6 / f ≤1.61, 0.54≤ f 7 / f ≤1.08, -1.81≤ f 8 / f ≤-0.74, 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 is the focal length of the seventh lens. f 8 represents the focal length of the eighth lens.

[0022] 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.

[0023] 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.

[0024] The beneficial effects of the technical solution provided by this invention are as follows: a. Through synergistic optimization of specific optical power allocation and overall structure, the focal length range is 14.5mm ≤ f ≤17mm, improving the lens's magnification and resolution, while effectively correcting edge distortion and aberrations, solving the pain point of edge image quality degradation, and achieving a significant improvement in edge image quality; b. By strictly controlling the ratio of the total lens length to the focal length within the range of 2.5 to 3, the total optical length is effectively controlled while ensuring optical performance and focal length, thus achieving lens miniaturization and structural compactness. c. The total effective focal length range of the lens is limited to 14.5mm or less. f While the field of view is ≤17mm, the field of view is between 30° and 38°, ensuring that the field of view is not too narrow while looking into the distance. Attached Figure Description

[0025] 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.

[0026] 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 3 The 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 5The 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 14 The 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 16The 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 25 The 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 27The 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

[0027] 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.

[0028] 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.

[0029] This invention aims to provide a medium-telephoto lens with an approximately 16mm focal length and improved edge image quality. Unlike traditional designs that trade length for image quality, this invention resolves the conflict between small size and high-resolution image plane through an innovative structure that shifts the optical power outward (the maximum optical power positive lens is not adjacent to the central aperture stop) and compact parameter constraints. This invention maintains the overall optical length... TTL With focal length fWith a ratio in an extremely compact range of 2.5 to 3, and a field of view limited to a medium to long focal length range of 30° to 38°, it effectively suppresses astigmatism, field curvature, and distortion, thus enabling both telephoto viewing and significantly improving the edge-to-center consistency of the lens's imaging quality.

[0030] 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.

[0031] 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, and also represents the object-side surface of the fourth lens L4 cemented with the third lens L3; S7 represents the image-side surface of the fourth lens L4; S8 represents the surface of the aperture stop L5; S9 represents the object-side surface of the fifth lens L6, and S10 represents the fifth lens... The image side of L6; S11 represents the object side of the sixth lens L7, S12 represents the image side of the sixth lens L7; S13 represents the object side of the seventh lens L8, S14 represents the image side of the seventh lens L8, and also represents the object side of the eighth lens L9 cemented with the seventh lens L8, S15 represents the image side of the eighth lens L9; S16 represents the object side of the filter L10 (such as an IR filter), S17 represents the image side of the filter L10; S18 represents the surface where the imaging surface L11 is located.

[0032] 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 The total length of the lens, in this embodiment of the invention, 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× D 1 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).

[0033] The lens in this embodiment is designed to achieve a maximum field of view of 30° to 38°, providing telephoto-level resolution, with a total focal length of 16mm or more, and parameters constrained to 2.5 ≤ TTL / f ≤3, by sorting the optical power and matching the surface shape, the lens has qualified OTF modulus and relative illumination, while the distortion is small, the image distortion is low, and the edge image quality is improved.

[0034] 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.

[0035] 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 and the third lens L3 are biconvex lenses with positive optical power; The fourth lens, L4, is a biconcave mirror with negative optical power; Both the fifth lens L6 and the sixth lens L7 have negative optical power. Their object side has a concave structure near the optical axis, and their image side has a convex structure near the optical axis. The seventh lens, L8, is a biconvex lens with positive optical power; The eighth lens L9 has negative optical power, its object side has a concave structure near the optical axis, and its image side has a convex structure near the optical axis.

[0036] The aforementioned negative-positive-positive-negative-negative-positive-positive-negative optical power sequence, combined with a specific surface shape, breaks the strict symmetry of the traditional double Gaussian (negative-positive-negative-positive) in terms of actual physical structure and aberration correction mechanism, but retains the potential of the flat image field of the double Gaussian. At the same time, the asymmetric structure allows for the correction of edge rays through a strong negative lens in the rear group (such as the eighth lens L9) in a narrow field of view (30°-38°).

[0037] In this embodiment, the third lens L3 and the fourth lens L4 form a cemented lens, and the difference in their Abbe constants is greater than 18, which is beneficial for correcting chromatic aberration, improving image quality, reducing assembly sensitivity, and increasing image plane size. Therefore, the third lens L3 and the fourth lens L4 form an achromatic lens group; similarly, the seventh lens L8 and the eighth lens L9 form an achromatic lens group.

[0038] In this embodiment, the optical lens satisfies: 30°≤ Fov ≤33.3°, 9.2mm≤ Y m ≤9.8mm, 12.1mm≤2× D 1≤13.6mm, 0.54mm≤ Y 1≤0.6mm, 44mm≤ TTL ≤46mm, 14.6mm≤ f ≤16.7mm, 1.68° / mm≤ Fov / Y m / 2≤1.75° / mm, 2.55≤ TTL / f ≤3; 0.78≤2× D 1 / f ≤0.88, 31.8≤ Y 1×180 / pi ≤33.8, -1.46≤ f 1 / f ≤-1.17, 0.88≤ f 2 / f ≤1.05, 0.56≤ f 3 / f ≤0.71, -0.44≤ f 4 / f ≤-0.32, -2≤ f5 / f ≤-1.65, 0.99≤ f 6 / f ≤1.25, 0.54≤ f 7 / f ≤0.68, -0.91≤ f 8 / f ≤-0.74, 0.18≤ bfl / TTL ≤0.32, 0.55≤ bfl / f ≤0.88, 0.046° / mm 2 ≤ Fov / (2× D 1) / TTL ≤0.062° / mm 2 ; 0.205≤ Y m / TTL ≤0.22; -16.1mm≤ r 32 ≤-15mm, -11mm≤ r 72 ≤-8.5mm, -5.45mm≤ r 51 ≤-4.85mm, -8mm≤ r 52 ≤-7mm; The optical axis distance from the image side of the first lens to the object side of the second lens d S2-S3 Between 7.15mm and 8.15mm; center thickness of the second lens d S3-S4 The center thickness of the third lens is between 2.6mm and 3.25mm. d S5-S6 The center thickness of the fourth lens is between 4.4mm and 5.5mm. d S6-S7 Between 1.2mm and 1.5mm; the optical axis distance from the object-side surface of the second lens to the image-side surface of the fourth lens. d S3-S7 Between 8.5mm and 10.5mm; the optical axis distance from the image-side surface of the fourth lens to the object-side surface of the fifth lens. d S7-S9 Between 5.25mm and 8.8mm; center thickness of the fifth lens d S9-S10 The center thickness of the sixth lens is between 1.02mm and 1.4mm. d S11-S12 The center thickness of the seventh lens is between 1.8mm and 2.4mm. d S13-S14 The center thickness of the eighth lens is between 2.5mm and 3.5mm.d S14-S15 Between 0.8mm and 1.2mm; the optical axis distance from the object-side surface of the fifth lens to the image-side surface of the eighth lens. d S9-S15 The distance from the image-side surface of the eighth lens to the imaging surface is between 7.2 mm and 8.1 mm. d S15-S18 (Right now bfl The distance between the image-side surface of the fifth lens and the object-side surface of the sixth lens is between 9.7 mm and 12.5 mm. d S10-S11 Between 0.01mm and 0.3mm; Among the eight lenses with optical power, the third lens has the largest center thickness. d S5-S6 The thickness ranges from 4.6mm to 5.2mm; the lens with the smallest center thickness is the eighth lens, whose center thickness is... d S14-S15 Between 0.85mm and 1.15mm.

[0039] The refractive index of the eight-element lens with optical power is between 1.57 and 1.98, and the difference between the maximum and minimum refractive index is between 0.08 and 0.3.

[0040] It can be seen that the focal length of the seventh lens, the positive lens with the highest optical power, is 9.567882mm, and the focal length of the entire lens group is... f Reaching approximately 15mm improves the lens's magnification and resolution. Among the eight lenses, the two with the highest optical power are the seventh lens (…). f 7=9.567882mm) and the third lens ( f (3=9.996677mm) Unlike the traditional design that concentrates the positive lens with the maximum optical power on the lens near the aperture (such as the middle group of a double Gaussian structure), this embodiment shifts the optical power outward. This overall balanced distribution of optical power can compensate for the correction of higher-order aberrations (such as higher-order spherical aberration and coma) when dealing with high-magnification sampling of small sensors, and avoids trailing or blurring at the edges of the image.

[0041] 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 In the table, if the radius of curvature is infinite, it means that the 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 5.9mm, and the variable distance D_2 has a variable range of 5mm to 8.5mm.

[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. The lens magnification is 0 when the object distance is infinity; 0.0515 when the object distance is 300mm; and 0.1433 when the object distance is 100mm.

[0044] 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 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. The table data in this embodiment uses rounding to obtain the calculated values.

[0045] Although the first lens L1, which is crescent-shaped, has negative optical power, its convex surface faces the object side, which gives it a strong ability to focus light on the edge rays of the field angle. This is beneficial for collecting light and reduces the requirements for the aperture of subsequent lenses, which is conducive to compact design. The second lens L2, the third lens L3, and the fourth lens L4 are compactly arranged to form a positive-positive-negative front refractive module. The biconvex second lens L2 and third lens L3 provide core positive optical power to balance the negative optical power of the first lens L1, and have strong spherical aberration correction capabilities, effectively collecting large-aperture light and improving central resolution. The biconcave fourth lens L4 can counteract the excessive positive spherical aberration and axial chromatic aberration accumulated by the first two positive lenses, and prevents the equivalent optical power of the first four lenses from becoming excessive, thereby reducing the aberration correction burden on the rear lens group and allowing the rear lens group to focus on fine correction of field curvature and astigmatism.

[0046] like Figure 1As 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.

[0047] The compact layout of the fifth lens L6 to the eighth lens L9 (arranged in a negative-positive-positive-negative optical power sequence) compresses the length of the group and minimizes the air gap between them. This results in a more compact propagation path for light within the group, which is beneficial for the coupling correction of higher-order aberrations. The fifth lens L6 receives light rays from the aperture stop. Since the aperture stop already limits its width, the fifth lens L6 acts as a negative lens, diverging edge rays and reducing the incident height of subsequent lenses, thereby reducing the aberration load on subsequent lenses. Furthermore, the object side of its concave structure corresponds to the image side of the concave structure of the fourth lens L4, which can doubly suppress aberrations in the off-axis field of view.

[0048] The sixth lens L7 and the seventh lens L8 are the most powerful components in the rear lens group, responsible for refocusing light. Their positive optical power pulls edge rays back to the image plane, reducing the incident angle of edge rays and thus improving edge resolution, solving the problem of edge blurring at telephoto views. The final eighth lens L9, with its negative optical power, can compensate for the positive optical power accumulated by the sixth lens L7 and the seventh lens L8, preventing excessive convergence of the image plane, maintaining the stability of the imaging system, and allowing for final fine-tuning of field curvature and distortion, ensuring image plane flatness throughout the entire field of view (30°-38°).

[0049] Among the lenses with positive optical power, the third lens L3 has the highest optical power with a focal length of 9.996677mm, followed by the seventh lens L8 with a focal length of 9.567882mm. This improves the lens's magnification and resolution, breaking the traditional optical power distribution pattern of the double Gaussian structure. It also shows that the front and rear groups of the lens in this embodiment are dominated by strong positive lenses. The third lens L3 acts as the front group engine, initially converging light from a wide field of view; the seventh lens L8 acts as the rear group engine, responsible for core imaging and balancing higher-order aberrations.

[0050] In this embodiment, the optical lens can be integrated with an electronic image sensor to form a camera device (line scan camera or area scan camera) for use in industrial inspection equipment (such as automated optical inspection equipment).

[0051] 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 2It can be seen that, in millimeters, TS 0.0000 (mm) represents a central field-of-view OTF modulus of approximately 52%, while TS 2.3750 (mm) represents a non-central field-of-view (0.5 field of view) OTF modulus of approximately 40%. From... Figure 3 It can be seen that, in millimeters, the OTF modulus of the central field of view represented by TS 0.0000 (mm) is approximately 52%, while the OTF modulus of the peripheral field of view represented by TS 4.7500 (mm) is approximately 45%. From... Figure 4 As can be seen, in millimeters, TS 0.0000 (mm) represents a center field of view OTF modulus of approximately 51%, and TS 4.2750 (mm) represents a non-center field of view (0.9 field of view) OTF modulus of approximately 45%, indicating that the lens can produce clear images.

[0052] Figures 5 to 7 The 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 in the image. The horizontal axis represents the Y-field of view, with units in millimeters (mm), and the vertical axis represents the relative illumination (dimensionless, normalized value). Figure 5 It can be seen that the optical lens in this specific embodiment has a relative illumination of approximately 76% 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 79%, 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 about 84%, 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.

[0053] 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 0.42%. Figure 9 The maximum distortion is approximately -0.15%. Figure 10 The maximum distortion is approximately -0.69%, meaning that the optical lens in this embodiment has low distortion and low image distortion.

[0054] 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 20To 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 surface S11 of the sixth lens L7 in the second embodiment is convex, and the image side surface S15 of the eighth lens L9 is concave.

[0055] The Abbe constants of the first to fourth lenses are high, low, high, low, and the difference in the Abbe constant values ​​of adjacent lenses is greater than 20, thus forming an achromatic lens group. Similarly, the fifth lens L6, the sixth lens L7, the seventh lens L8, and the eighth lens L9 form an achromatic lens group.

[0056] In this embodiment, the optical lens satisfies: 31°≤ Fov ≤38°, 9.2mm≤ Y m ≤9.8mm, 13.2mm≤2× D 1≤15.3mm, 0.5mm≤ Y 1≤0.63mm, 43.6mm≤ TTL ≤46.6mm, 14.7mm≤ f ≤16.2mm, 1.68° / mm≤ Fov / Y m / 2≤1.84° / mm, 2.6≤ TTL / f ≤3; 0.85≤2× D 1 / f ≤0.99, 30.1≤ Y 1×180 / pi ≤33.8, -1.65≤ f 1 / f ≤-1.5, 0.99≤ f 2 / f ≤1.11, 0.58≤ f 3 / f ≤0.68, -0.4≤ f 4 / f ≤-0.34, -3.6≤ f 5 / f ≤-2.9, 1.35≤ f 6 / f ≤1.49, 0.95≤ f 7 / f ≤1.08, -1.81≤ f 8 / f ≤-1.56, 0.19≤ bfl / TTL ≤0.3, 0.58≤ bfl / f ≤0.85, 0.044° / mm 2 ≤ Fov / (2×D 1) / TTL ≤0.06° / mm 2 ; 0.202≤ Y m / TTL ≤0.225; -13.3mm≤ r 32 ≤-11.3mm, -22mm≤ r 72 ≤-20mm, -5.2mm≤ r 51 ≤-4.45mm, -7.4mm≤ r 52 ≤-6.5mm; The optical axis distance from the image side of the first lens to the object side of the second lens d S2-S3 Between 9mm and 10mm; center thickness of the second lens d S3-S4 The center thickness of the third lens is between 2.3mm and 3mm. d S5-S6 The center thickness of the fourth lens is between 3.8mm and 4.6mm. d S6-S7 Between 1.9mm and 2.7mm; the optical axis distance from the object-side surface of the second lens to the image-side surface of the fourth lens. d S3-S7 Between 9.1 mm and 11.3 mm; the optical axis distance from the image-side surface of the fourth lens to the object-side surface of the fifth lens. d S7-S9 Between 4.8mm and 6.5mm; center thickness of the fifth lens d S9-S10 The center thickness of the sixth lens is between 2mm and 2.72mm. d S11-S12 The center thickness of the seventh lens is between 1.63mm and 2.04mm. d S13-S14 The center thickness of the eighth lens is between 1.75mm and 2.25mm. d S14-S15 Between 0.7mm and 0.95mm; the optical axis distance from the object-side surface of the fifth lens to the image-side surface of the eighth lens. d S9-S15 The distance from the image-side surface of the eighth lens to the optical axis of the imaging surface is between 6.7 mm and 7.55 mm. d S15-S18 The optical axis distance between the image-side surface of the fifth lens and the object-side surface of the sixth lens is between 9.7 mm and 12.9 mm. d S10-S11 Between 0.01mm and 0.2mm; Among the eight lenses with optical power, the third lens has the largest center thickness. d S5-S6 The thickness ranges from 3.75mm to 4.55mm; the lens with the smallest center thickness is the eighth lens, whose center thickness is... d S14-S15 Between 0.75mm and 0.9mm.

[0057] The refractive index of the eight-element lens with optical power is between 1.5 and 1.8, and the difference between the maximum and minimum refractive index is between 0.05 and 0.13.

[0058] It can be seen that the two lenses with the greater optical power among the eight lenses are the third lens ( f 3=9.855588mm) and the seventh lens ( f 7 = 15.748595mm), the entire focal length of the lens. f Reaching approximately 15mm, this improves the lens's magnification and resolution. Unlike traditional designs that concentrate the maximum optical power positive lens on the lens near the aperture stop (such as the middle group of a double Gaussian structure), this embodiment shifts the optical power outward. In this embodiment, both the front and rear groups of the lens are dominated by strong positive lenses. The third lens L3 acts as the front group engine, initially converging light from a wide field of view; the seventh lens L8 acts as the rear group engine, responsible for core imaging and balancing higher-order aberrations. When dealing with high-magnification sampling of small sensors, it can compensate for the correction of higher-order aberrations (such as higher-order spherical aberration and coma), avoiding trailing or blurring at the edges of the image.

[0059] 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 In the table, if the radius of curvature is infinite, it means that the corresponding surface number represents a plane.

[0060] 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 2.8mm to 4.6mm, and the variable distance D_2 has a variable range of 5.1mm to 8.5mm.

[0061] 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 The lens magnification is 0 when the object distance is infinity; 0.0499 when the object distance is 300mm; and 0.1402 when the object distance is 100mm.

[0062] 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 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. The table data in this embodiment uses rounding to obtain the calculated values.

[0063] 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 58.5%, while TS 4.2750 (mm) represents a non-central field-of-view (0.9 field of view) OTF modulus of approximately 48%. From... Figure 13 It can be seen that, in millimeters, TS 0.0000 (mm) represents a central field-of-view OTF modulus of approximately 58%, while TS 4.2750 (mm) represents a non-central field-of-view (0.9 field of view) OTF modulus of approximately 46%. From... Figure 14 As can be seen, in millimeters, TS 0.0000 (mm) represents a central field of view OTF modulus of approximately 56%, and TS 4.7500 (mm) represents an edge field of view OTF modulus of approximately 47%, indicating that the lens can produce clear images.

[0064] Figures 15 to 17 The images above show the relative illumination curves of the lens in the second 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 15It can be seen that the optical lens in this specific embodiment has a relative illumination of approximately 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 16 It can be seen that the relative illumination corresponding to a Y-field of view of approximately 4.75mm is approximately 92%, reflecting that this 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 about 95%, 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.

[0065] 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 -1.37%. Figure 20 The maximum distortion is approximately -1.76%, meaning that the optical lens in this embodiment has relatively small distortion and low image distortion.

[0066] 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 surface S11 of the sixth lens L7 in the third embodiment is convex.

[0067] The Abbe constants of the first to fourth lenses are high, low, high, low. Therefore, the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 form an achromatic lens group. Similarly, the fifth lens L6 and the sixth lens L7 form an achromatic lens group, and the seventh lens L8 and the eighth lens L9 form an achromatic lens group.

[0068] In this embodiment, the optical lens satisfies: 31°≤ Fov ≤37.5°, 9.2mm≤ Y m ≤9.8mm, 12.7mm≤2× D 1≤14.3mm, 0.5mm≤ Y 1≤0.61mm, 43.3mm≤ TTL ≤47mm, 14.88mm≤ f≤16.8mm, 1.68° / mm≤ Fov / Y m / 2≤1.84° / mm, 2.6≤ TTL / f ≤3; 0.83≤2× D 1 / f ≤0.92, 30.1≤ Y 1×180 / pi ≤34, -1.68≤ f 1 / f ≤-1.5, 0.99≤ f 2 / f ≤1.09, 0.58≤ f 3 / f ≤0.72, -0.44≤ f 4 / f ≤-0.34, -2.92≤ f 5 / f ≤-1.9, 1.47≤ f 6 / f ≤1.61, 0.8≤ f 7 / f ≤0.92, -1.76≤ f 8 / f ≤-1.52, 0.19≤ bfl / TTL ≤0.3, 0.58≤ bfl / f ≤0.85, 0.046° / mm 2 ≤ Fov / (2× D 1) / TTL ≤0.058° / mm 2 ; 0.196≤ Y m / TTL ≤0.223; -14mm≤ r 32 ≤-12mm, -11.8mm≤ r 72 ≤-9.8mm, -5.6mm≤ r 51 ≤-4.6mm, -7.5mm≤ r 52 ≤-6.8mm; The optical axis distance from the image side of the first lens to the object side of the second lens d S2-S3 Between 9mm and 10.2mm; center thickness of the second lens d S3-S4 The center thickness of the third lens is between 2.6mm and 3.4mm. d S5-S6The center thickness of the fourth lens is between 4mm and 4.6mm. d S6-S7 Between 2.2mm and 2.95mm; the optical axis distance from the object-side surface of the second lens to the image-side surface of the fourth lens. d S3-S7 Between 8.96mm and 10.9mm; the optical axis distance from the image-side surface of the fourth lens to the object-side surface of the fifth lens. d S7-S9 Between 4.8mm and 6.4mm; center thickness of the fifth lens d S9-S10 The center thickness of the sixth lens is between 1.93mm and 2.35mm. d S11-S12 The center thickness of the seventh lens is between 1.3mm and 1.9mm. d S13-S14 The center thickness of the eighth lens is between 2.2mm and 3.2mm. d S14-S15 Between 0.7mm and 0.95mm; the optical axis distance from the object-side surface of the fifth lens to the image-side surface of the eighth lens. d S9-S15 The optical axis distance between the image-side surface of the fifth lens and the object-side surface of the sixth lens is between 7mm and 8.1mm. d S10-S11 Between 0.01mm and 0.2mm; Among the eight lenses with optical power, the third lens has the largest center thickness. d S5-S6 The thickness ranges from 4mm to 4.6mm; the lens with the smallest center thickness is the eighth lens, whose center thickness is... d S14-S15 Between 0.72mm and 0.9mm.

[0069] The refractive index of the eight-element lens with optical power ranges from 1.57 to 2.03, with the difference between the maximum and minimum refractive index ranging from 0.3 to 0.48.

[0070] It can be seen that the two lenses with the greater optical power among the eight lenses are the third lens ( f 3=10.278199mm) and the seventh lens ( f 7=13.3864mm), the entire focal length of the lens. fReaching approximately 15mm improves the lens's magnification and resolution. Unlike the traditional design that concentrates the positive lens with the maximum optical power on the lens near the aperture (such as the middle group of a double Gaussian structure), this embodiment shifts the optical power outward. This overall balanced distribution of optical power can compensate for the correction of higher-order aberrations (such as higher-order spherical aberration and coma) when dealing with high-magnification sampling of small sensors, thus avoiding trailing or blurring at the edges of the image.

[0071] 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 In the table, if the radius of curvature is infinite, it means that the corresponding surface number represents a plane.

[0072] 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 2.75mm to 4.45mm, and the variable distance D_2 has a variable range of 4.85mm to 8.5mm.

[0073] 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 The lens magnification is 0 when the object distance is infinity; 0.0498 when the object distance is 300mm; and 0.1399 when the object distance is 100mm.

[0074] 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 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 The table data in this embodiment uses rounding to obtain the calculated values.

[0075] Based on a lens resolution of 166LP / mm, Figures 22 to 24The 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 58%, while 4.2750 (mm) represents a non-central field-of-view (0.9 field of view) OTF modulus of approximately 48%. From... Figure 23 It can be seen that, in millimeters, TS 0.0000 (mm) represents a central field-of-view OTF modulus of approximately 58%, while 4.2750 (mm) represents a non-central field-of-view (0.9 field of view) OTF modulus of approximately 42%. From... Figure 24 As can be seen, in millimeters, TS 0.0000 (mm) represents a central field of view OTF modulus of approximately 55%, and TS 4.7500 (mm) represents an edge field of view OTF modulus of approximately 50%, indicating that the lens can produce clear images.

[0076] Figures 25 to 27 The 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 in the image. The horizontal axis represents the Y-field of view, measured in millimeters (mm), and the vertical axis represents the relative illumination (a dimensionless, normalized value). Figure 25 It can be seen that the optical lens in this specific embodiment has a relative illumination of approximately 81.5% 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 82%, 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 about 89%, which reflects 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.

[0077] 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 -1.4%. Figure 30The maximum distortion is approximately -1.85%, meaning that the optical lens in this embodiment has relatively small distortion and low image distortion.

[0078] 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.

[0079] 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 object side of the first lens has a convex structure near the optical axis, and its image side has a concave structure near the optical axis. The first lens also has negative optical power. The object-side and image-side surfaces of the second, third, and seventh lenses are all convex near the optical axis; The object-side and image-side surfaces of the fourth lens are both concave near the optical axis, and the third lens and the fourth lens constitute a cemented lens. The object side of the fifth lens has a concave structure near the optical axis, and its image side has a convex structure near the optical axis. The fifth lens also has negative optical power. The image-side surface of the sixth lens is convex near the optical axis, and the sixth lens has positive optical power. The object side of the eighth lens is concave near the optical axis, and the eighth lens has negative optical power. The seventh lens and the eighth lens together form a cemented lens. The optical lens satisfies: 14.5mm ≤ f ≤17mm, 30°≤ Fov ≤38°, and 2.5≤ TTL / f ≤3, where, f This refers to the entire focal length of the lens. Fov The maximum field of view 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.

2. The optical lens according to claim 1, characterized in that, The optical axis distance from the image side of the first lens to the object side of the second lens is between 7.1 mm and 10.25 mm. The center thickness of the second lens is between 2.3 mm and 3.4 mm, the center thickness of the third lens is between 3.8 mm and 5.5 mm, and the center thickness of the fourth lens is between 1.2 mm and 2.95 mm. The optical axis distance from the object side of the second lens to the image side of the fourth lens is between 8.5 mm and 11.5 mm.

3. The optical lens according to claim 1, characterized in that, The optical axis distance from the image side of the fourth lens to the object side of the fifth lens is between 4.8 mm and 8.8 mm. The center thickness of the fifth lens is between 1 mm and 2.75 mm, the center thickness of the sixth lens is between 1.3 mm and 2.4 mm, the center thickness of the seventh lens is between 1.75 mm and 3.5 mm, and the center thickness of the eighth lens is between 0.7 mm and 1.2 mm. The optical axis distance from the object side of the fifth lens to the image side of the eighth lens is between 6.7 mm and 8.2 mm, and the optical axis distance from the image side of the eighth lens to the imaging surface is between 9.7 mm and 12.9 mm.

4. The optical lens according to claim 1, characterized in that, The optical lens satisfies: 43mm≤ TTL ≤47mm; 0.044≤ Fov / (2× D 1) / TTL ≤0.062; 0.18≤ bfl / TTL ≤0.32； 0.196≤ Y m / TTL ≤0.225; where, 2× D 1 is the effective diameter of the first lens. Fov The maximum field of view of the lens. bfl The rear focal length of the lens. Y m This represents the image height corresponding to the maximum field of view.

5. The optical lens according to claim 1, characterized in that, The focal length of the positive lens with the highest optical power is between 8.8mm and 11mm; Among the eight lenses with optical power, the positive lens with the highest optical power is either the seventh lens or the third lens.

6. The optical lens according to claim 1, characterized in that, The lens satisfies: 1.68≤ Fov / Y m / 2≤1.84, where, Y m The image height corresponding to the maximum field of view; And / or, 30≤ Y 1×180 / pi ≤34, where, Y 1 represents the lens image height when the half-field of view is 1°. pi Pi; And / or, 0.76≤2× D 1 / f ≤0.99, where 2× D 1 represents the effective diameter of the first lens; And / or, 0.55≤ bfl / f ≤0.88, where, bfl This is the rear focal length of the lens.

7. The optical lens according to claim 1, characterized in that, The radius of curvature of the cemented surface between the third and fourth lenses satisfies: -16.1mm ≤ r 32 ≤-11.3mm, where, r 32 Let be the radius of curvature of the image-side surface of the third lens; The radius of curvature of the cemented surface between the seventh and eighth lenses satisfies: -22mm ≤ r 72 ≤-8.5mm, where, r 72 Let be the radius of curvature of the image-side surface of the seventh lens.

8. The optical lens according to claim 1, characterized in that, The radius of curvature of the fifth lens satisfies: -5.6mm ≤ r 51 ≤-4.45mm, -8mm≤ r 52 ≤-6.5mm, 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; The optical axis distance between the image side of the fifth lens and the object side of the sixth lens is between 0.01 mm and 0.3 mm.

9. The optical lens according to claim 1, characterized in that, Among the eight lenses with optical power, the lens with the largest center thickness is the third lens, with a center thickness ranging from 3.75 mm to 5.2 mm. Among the eight lenses with optical power, the lens with the smallest center thickness is the eighth lens, with a center thickness ranging from 0.7 mm to 1.15 mm.

10. The optical lens according to claim 1, characterized in that, The lens satisfies: 9.2mm≤ Y m ≤9.8mm, of which, Y m The image height corresponding to the maximum field of view; And / or, 0.5mm≤ Y 1≤0.63mm, where, Y 1 represents the lens image height when the half-field angle is 1°; And / or, 12.1mm≤2× D 1≤15.3mm, where 2× D 1 represents the effective diameter of the first lens.

11. The optical lens according to claim 1, characterized in that, All eight lenses with optical power are spherical mirrors.

12. The optical lens according to claim 1, characterized in that, The refractive index of the eight-element lens with optical power ranges from 1.5 to 2.035, with the difference between the maximum and minimum refractive index ranging from 0.05 to 0.

48.

13. 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 5.9mm; 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 4.8 mm to 8.5 mm.

14. The optical lens according to any one of claims 1 to 13, characterized in that, The focal length of each lens satisfies the following condition: -1.68 ≤ f 1 / f ≤-1.17, 0.88≤ f 2 / f ≤1.11, 0.56≤ f 3 / f ≤0.72, -0.44≤ f 4 / f ≤-0.32, -3.6≤ f 5 / f ≤-1.65, 0.99≤ f 6 / f ≤1.61, 0.54≤ f 7 / f ≤1.08, -1.81≤ f 8 / f ≤-0.74, 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.

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