Optical lens

Abstract

The application discloses an optical lens, which comprises, in sequence from an object side to an imaging surface along an optical axis, a first lens with negative focal length, the object side of which is a convex surface and the image side of which is a concave surface; a second lens with negative focal length, the object side of which is a concave surface and the image side of which is a concave surface; a third lens with positive focal length, the object side of which is a convex surface and the image side of which is a convex surface; a fourth lens with positive focal length, the object side of which is a convex surface and the image side of which is a convex surface; a fifth lens with negative focal length, the object side of which is a concave surface and the image side of which is a concave surface; a sixth lens with positive focal length, the object side of which is a convex surface and the image side of which is a convex surface; a seventh lens with positive focal length, the object side of which is a convex surface and the image side of which is a convex surface; and an eighth lens with positive focal length, the object side of which is a convex surface and the image side of which is a convex surface. The optical lens provided by the application has one or more advantages of large wide angle, day and night focus, and high pixel.

Description

Optical lens Technical Field

[0001] This invention relates to the field of imaging lens technology, and in particular to an optical lens. Background Technology

[0002] With the rapid development of technology, wide-angle lenses, due to their advantages of large field of view and wide shooting area, are widely used in security, automotive, smart home and other fields. However, due to the differences in application environments, consumers have different but increasingly higher performance requirements for lenses. For example, in some complex application scenarios, the lens is required not only to remain in focus under conditions of large temperature differences, but also to cover a wide spectral range from visible light to near-infrared light, typically including the band from 400nm to 1000nm or even wider, such as 1700nm. This requires the lens to work under different lighting conditions, maintaining consistent image sharpness from visible light during the day to infrared light at night.

[0003] Most conventional lenses on the market can only image within a single band of visible or infrared light, resulting in a narrow imaging spectrum, lack of day and night co-focus capability, and low image quality, which cannot adequately meet the diverse market demands. Summary of the Invention

[0004] The purpose of this invention is to provide an optical lens that has at least one or more of the following advantages: wide-angle, day and night co-focus, and high pixel count.

[0005] To this end, the present invention provides an optical lens, which consists of eight lenses and sequentially includes, along the optical axis from the object side to the imaging surface: a first lens with a negative optical power, the object side surface of the first lens is convex, and the image side surface of the first lens is concave; a second lens with a negative optical power, the object side surface of the second lens is concave, and the image side surface of the second lens is concave; a third lens with a positive optical power, the object side surface of the third lens is convex, and the image side surface of the third lens is convex; a fourth lens with a positive optical power, the object side surface of the fourth lens is convex, and the image side surface of the fourth lens is convex; a fifth lens with a negative optical power, the object side surface of the fifth lens is concave, and the image side surface of the fifth lens is concave; a sixth lens with a positive optical power, the object side surface of the sixth lens is convex, and the image side surface of the sixth lens is convex; a seventh lens with a positive optical power, the object side surface of the seventh lens is convex, and the image side surface of the seventh lens is convex; an eighth lens with a positive optical power, the object side surface of the eighth lens is convex, and the image side surface of the eighth lens is convex. Among them, at least one of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens is a glass lens. In some embodiments, the fifth lens and the sixth lens form a cemented lens.

[0006] In some embodiments, the working spectral range of the optical lens is 400 - 1700 nm, which can cover a wide spectral range from visible light to near-infrared light. That is, the optical lens can work under different lighting conditions and has high-quality imaging when switching from visible light during the day to infrared light irradiation at night.

[0007] In some embodiments, the maximum field of view FOV of the optical lens satisfies: 85° < FOV < 100°.

[0008] In some embodiments, the effective focal length f of the optical lens satisfies: 4.0 mm < f < 9.0 mm.

[0009] In some embodiments, the image height IH corresponding to the maximum field of view of the optical lens satisfies: 5.5 mm < IH < 13 mm.

[0010] In some embodiments, the optical lens satisfies the conditional formula: 2 < fb / f < 3; where fb represents the combined focal length of the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens.

[0011] In some embodiments, the optical lens satisfies the conditional formula: 1.2 < IH / f < 1.5; where IH represents the image height corresponding to the maximum field of view of the optical lens, and f represents the effective focal length of the optical lens.

[0012] In some embodiments, the optical lens satisfies the conditional expression: 1 < BFL / f < 2.5; where BFL represents the back focal length of the optical lens.

[0013] In some embodiments, the optical lens satisfies the conditional expressions: -50 < f1 / f < -6, -2 < f2 / f < -0.5; where f1 represents the effective focal length of the first lens and f2 represents the effective focal length of the second lens.

[0014] In some embodiments, the optical lens satisfies the conditional expressions: 1 < f3 / f < 5, 1 < f4 / f < 5; where f3 represents the effective focal length of the third lens and f4 represents the effective focal length of the fourth lens.

[0015] In some embodiments, the optical lens satisfies the conditional expressions: 5 < f7 / f < 50, 2 < f8 / f < 5; where f7 represents the effective focal length of the seventh lens and f8 represents the effective focal length of the eighth lens.

[0016] In some embodiments, the optical lens satisfies the conditional expression: 3 < f1 / f2 < 50; where f1 represents the effective focal length of the first lens and f2 represents the effective focal length of the second lens.

[0017] In some embodiments, the optical lens satisfies the conditional expression: 0.3 < f3 / f4 < 0.95; where f3 represents the effective focal length of the third lens and f4 represents the effective focal length of the fourth lens.

[0018] In some embodiments, the fifth lens and the sixth lens form a cemented lens, and the optical lens satisfies the conditional expressions: -8 < f56 / f < -2, -0.8 < f5 / f6 < -0.4; where f5 represents the effective focal length of the fifth lens, f6 represents the effective focal length of the sixth lens, and f56 represents the combined focal length of the fifth lens and the sixth lens.

[0019] In some embodiments, the optical lens satisfies the conditional expressions: 5 < CT23 / CT2 < 7.5, 1.4 < CT23 / CT3 < 2.5; where CT2 represents the central thickness of the second lens, CT3 represents the central thickness of the third lens, and CT23 represents the distance between the second lens and the third lens on the optical axis.

[0020] In some embodiments, the optical lens satisfies the conditional formula: 0.4 < CT1 / CT8 < 0.8, 1.2 < DM11 / DM82 < 2; where CT1 represents the central thickness of the first lens, CT8 represents the central thickness of the eighth lens, DM11 represents the effective aperture of the object side of the first lens, and DM82 represents the effective aperture of the image side of the eighth lens.

[0021] In some embodiments, the optical lens satisfies the conditional formula: 1.8 < CT3 / CT4 < 3.0, 1.5 < DM31 / DM41 < 3; where CT3 represents the central thickness of the third lens, CT4 represents the central thickness of the fourth lens, DM31 represents the effective aperture of the object side of the third lens, and DM41 represents the effective aperture of the object side of the fourth lens.

[0022] In some embodiments, an aperture stop is provided between the third lens and the fourth lens.

[0023] In some embodiments, a filter is provided between the eighth lens and the imaging surface.

[0024] In some embodiments, at least one of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens is an aspherical lens.

[0025] Compared with the prior art, the optical lens provided by the present invention uses eight lenses. Through specific surface shape combinations and reasonable focal power distributions, the lens can operate under different lighting conditions and can achieve high-quality imaging under both visible light during the day and infrared light irradiation at night. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0027] FIG. 1 is a schematic structural diagram of an optical lens in the first embodiment of the present invention.

[0028] FIG. 2 is a MTF curve diagram of the optical lens in the first embodiment of the present invention under visible light.

[0029] FIG. 3 is a MTF curve diagram of the optical lens in the first embodiment of the present invention under infrared light.

[0030] FIG. 4 is a relative illuminance curve diagram of the optical lens in the first embodiment of the present invention.

[0031] FIG. 5 is a MTF curve diagram of the optical lens in the second embodiment of the present invention under visible light.

[0032] Figure 6 is an MTF curve of the optical lens under infrared light in the second embodiment of the present invention.

[0033] Figure 7 is a relative illumination curve of the optical lens in the second embodiment of the present invention.

[0034] Figure 8 is an MTF curve of the optical lens under visible light in the third embodiment of the present invention.

[0035] Figure 9 is an MTF curve of the optical lens under infrared light in the third embodiment of the present invention.

[0036] Figure 10 is a relative illumination curve of the optical lens in the third embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be thorough and complete.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Throughout this specification, the same reference numerals refer to the same elements.

[0039] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of the invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0040] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0041] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane is called the image-side surface of the lens.

[0042] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0043] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0044] This invention provides an optical lens that includes, along the optical axis from the object side to the imaging plane, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a filter, with the optical centers of each lens located on the same straight line.

[0045] In some embodiments, the first lens is configured to have negative optical power, with its object side being convex and its image side being concave. This allows it to collect as much light as possible from a wide field of view into the rear optical system and to quickly diverge large-angle light rays passing through the first lens. It also facilitates aberration correction of large-angle light rays by the rear optical system, thereby improving the image quality of the lens.

[0046] In some embodiments, the second lens is configured to have negative optical power, with its object side and image side being concave, which can further diverge and adjust the incident light, thereby increasing the light flux entering the system and improving the relative illumination of the system.

[0047] In some embodiments, the third lens is configured to have positive optical power, with its object side and image side being convex. It can converge and adjust the light rays emitted from the first and second lenses, and can lower the height at which the light rays are incident on the subsequent optical system to make the light path more stable. It can also correct some aberrations and distortions, thereby improving the lens's resolving power.

[0048] In some embodiments, the fourth lens is configured to have positive optical power, with its object side and image side being convex. This can further converge the light rays and adjust the trajectory of the light rays in the central and peripheral fields of view to make the transition smoother, thereby balancing various aberrations generated by the front lens and improving the imaging quality of the lens.

[0049] In some embodiments, the fifth lens and the sixth lens form a cemented lens, which can effectively balance the chromatic aberration of each pupil, effectively reduce the back focal shift of infrared light, and achieve the effect of day and night confocal. At the same time, the fifth lens is set to have a negative focal power and the sixth lens is set to have a positive focal power, and the object side of the fifth lens is concave and the image side of the sixth lens is convex, which can effectively eliminate the specular reflection ghost images of the fifth and sixth lenses and improve the imaging quality.

[0050] In some embodiments, the seventh lens is set to have a positive focal power, its object side is convex and its image side is convex; the eighth lens is set to have a positive focal power, its object side is convex and its image side is convex; the seventh and eighth lenses are set as double convex lenses, which can converge and adjust the light rays passing through the front lens group, increase the area of the light rays entering the imaging surface, realize the large image surface of the lens, and improve the imaging quality of the lens.

[0051] In some embodiments, the aperture stop is arranged between the third lens and the fourth lens, which can effectively converge the light rays entering the optical system, and can balance the focal power distribution and aberration of the lens groups before and after the aperture stop, ensure the balance of the incident angles of the light rays of the front and rear lenses, reduce the lens aperture at the rear end of the optical system, reduce the sensitivity of the lens, and improve the stability of the optical lens.

[0052] In some embodiments, the working spectral range of the optical lens is 400~1700nm, which can cover a wide spectral range from visible light to near infrared light, that is, the optical lens can work under different lighting conditions, and has high-quality imaging from the visible light during the day to the infrared light irradiation at night.

[0053] In some embodiments, the optical lens satisfies the conditional formula: 2 < fb / f < 3; where fb represents the combined focal length of the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens. Meeting the above conditions, by reasonably setting the proportion of the focal lengths of the lens group after the aperture stop, it is beneficial to the smooth transition of light rays, so that the light rays enter the imaging surface at a relatively gentle angle as much as possible, reduce the influence of incident light of different wavelength bands on the system sensitivity and relative illuminance, and ensure that the lens has high imaging quality under different lighting conditions, and achieve the wide spectral imaging effect of day and night confocal.

[0054] In some embodiments, the optical lens satisfies the conditional formula: -2 < fa / fb < 2; where fa represents the combined focal length of the first lens, the second lens, and the third lens, and fb represents the combined focal length of the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens. By satisfying the above conditions and reasonably setting the focal length relationship between the lens groups before and after the aperture, the aberration of the system can be better corrected, enabling the lens to have a high resolution under different lighting conditions. Especially when the optical lens forms an image in a relatively dark environment, such as in the state of an infrared light source, the influence of noise caused by too weak light can be reduced, thereby improving the imaging quality and enabling the optical lens to meet the imaging requirements under different light fluxes.

[0055] In some embodiments, the optical lens satisfies the conditional formula: 1.2 < IH / f < 1.5, where IH represents the image height corresponding to the maximum field angle of the optical lens, and f represents the effective focal length of the optical lens. By satisfying the above conditions and reasonably controlling the ratio of the image height to the focal length of the optical lens, both the wide-angle characteristic can be achieved to meet the large wide-angle shooting requirements, and the large image plane characteristic can be achieved to improve the imaging quality of the optical lens. More preferably, by satisfying the above conditions, the maximum field angle FOV of the optical lens can be better achieved to satisfy 85° < FOV < 100°, and the image height IH corresponding to the maximum field angle of the optical lens satisfies 5.5 mm < IH < 13 mm.

[0056] In some embodiments, the optical lens satisfies the conditional formula: 1 < BFL / f < 2.5; where BFL represents the back focal length of the optical lens. By satisfying the above conditions and setting the optical lens to have a relatively large back focal length, it is beneficial to reduce the interference between the lens and the imaging chip and improve the assembly yield.

[0057] In some embodiments, the optical lens satisfies the conditional formula: -50 < f1 / f < -6, 1 < R1 / R2 < 1.8; where f1 represents the effective focal length of the first lens, R1 represents the curvature radius of the object side of the first lens, and R2 represents the curvature radius of the image side of the first lens. By satisfying the above conditions and reasonably setting the meniscus shape of the first lens, as much light as possible in the large field of view can be collected, the field angle of the optical lens can be expanded, and at the same time, the light can enter the rear optical system smoothly, ensuring the imaging quality of the optical lens.

[0058] In some embodiments, the optical lens satisfies the conditional formula: -2 < f2 / f < -0.5, -15 < R3 / R4 < -1; where f2 represents the effective focal length of the second lens, R3 represents the curvature radius of the object side surface of the second lens, and R4 represents the curvature radius of the image side surface of the second lens. Satisfying the above conditions can further facilitate the divergence of incident light, enabling better optimization of system aberration at a large field angle and improving the overall imaging quality.

[0059] In some embodiments, the optical lens satisfies the conditional formula: 1 < f3 / f < 5, -1 < R5 / R6 < -0.5; where f3 represents the effective focal length of the third lens, R5 represents the curvature radius of the object side surface of the third lens, and R6 represents the curvature radius of the image side surface of the third lens. Satisfying the above conditions, by reasonably setting the focal length and surface shape of the third lens, it is beneficial to converge light and make the light transition smoothly, reduce the sensitivity of the optical lens, and at the same time facilitate the regulation of the field angle of the optical lens, reduce the field curvature and distortion of the edge field, and improve the imaging quality of the optical lens.

[0060] In some embodiments, the optical lens satisfies the conditional formula: 1 < f4 / f < 5, -6 < R7 / R8 < -0.5; where f4 represents the effective focal length of the fourth lens, R7 represents the curvature radius of the object side surface of the fourth lens, and R8 represents the curvature radius of the image side surface of the fourth lens. Satisfying the above conditions, by reasonably setting the focal length and surface shape of the fourth lens, it is beneficial to the smooth transition of light, reduce the correction difficulty of edge aberration and distortion, and enable the lens to have a small distortion while achieving a large field angle.

[0061] In some embodiments, the optical lens satisfies the conditional formula: 5 < f7 / f < 50, -5 < R12 / R13 < -0.1; where f7 represents the effective focal length of the seventh lens, R12 represents the curvature radius of the object side surface of the seventh lens, and R13 represents the curvature radius of the image side surface of the seventh lens. Satisfying the above conditions, the focal length and surface shape of the seventh lens can be reasonably set, which is beneficial to balancing the aberration brought by the front lens group and improving the high-quality imaging of the lens.

[0062] In some embodiments, the optical lens satisfies the conditional formula: 2 < f8 / f < 5, -0.2 < R14 / R15 < -0.02; where f8 represents the effective focal length of the eighth lens, R14 represents the curvature radius of the object side surface of the eighth lens, and R15 represents the curvature radius of the image side surface of the eighth lens. Satisfying the above conditions, by reasonably setting the focal length and surface shape of the eighth lens, the light convergence can be accelerated, thereby increasing the height of light focusing, while increasing the photosensitive area of the image plane, effectively improving the imaging quality of the optical system.

[0063] In some embodiments, the optical lens satisfies the conditional formula: 3 < f1 / f2 < 50; where f1 represents the effective focal length of the first lens and f2 represents the effective focal length of the second lens. Meeting the above conditions, by reasonably setting the focal length relationship between the first and second lenses, it is beneficial to converge the divergence angle of incident light, so that the system aberration can be better optimized at a large field angle, improving the overall imaging quality.

[0064] In some embodiments, the optical lens satisfies the conditional formula: 0.3 < f3 / f4 < 0.95; where f3 represents the effective focal length of the third lens and f4 represents the effective focal length of the fourth lens. Meeting the above conditions, by reasonably setting the focal length relationship between the third and fourth lenses before and after the aperture stop, it is beneficial to the smooth transition of light, reducing the correction difficulty of marginal aberration and distortion, and enabling the lens to have a small distortion while achieving a large field angle.

[0065] In some embodiments, the fifth lens and the sixth lens form a cemented lens, and the optical lens satisfies the conditional formulas: -8 < f56 / f < -2, -0.8 < f5 / f6 < -0.4; where f5 represents the effective focal length of the fifth lens, f6 represents the effective focal length of the sixth lens, and f56 represents the combined focal length of the fifth lens and the sixth lens. Meeting the above conditions, the fifth lens and the sixth lens adopt a cemented structure. On the one hand, it can effectively eliminate the chromatic aberration of the system, and on the other hand, it can effectively eliminate the specular reflection ghost image between the fifth lens and the sixth lens, improving the imaging quality.

[0066] In some embodiments, the optical lens satisfies the conditional formulas: 5 < CT23 / CT2 < 7.5, 1.4 < CT23 / CT3 < 2.5; where CT2 represents the central thickness of the second lens, CT3 represents the central thickness of the third lens, and CT23 represents the distance between the second lens and the third lens on the optical axis. Meeting the above conditions, by reasonably setting the relationship between the central thicknesses of the second and third lenses and the air gap, it can effectively mitigate the degree of light deflection, effectively reduce the field curvature and distortion of the system, and improve the imaging quality.

[0067] In some embodiments, the optical lens satisfies the conditional formulas: 1.8 < CT3 / CT4 < 3, 1.5 < DM31 / DM41 < 3; where CT3 represents the central thickness of the third lens, CT4 represents the central thickness of the fourth lens, DM31 represents the effective aperture of the object side of the third lens, and DM41 represents the effective aperture of the object side of the fourth lens. Meeting the above conditions is beneficial to the processing and assembly of the lens, improving the production yield, and at the same time enabling light to enter the rear optical system smoothly, ensuring the imaging quality of the optical lens.

[0068] In some embodiments, the optical lens satisfies the conditional formula: 0.4 < CT1 / CT8 < 0.8, 1.2 < DM11 / DM82 < 2; where CT1 represents the central thickness of the first lens, CT8 represents the central thickness of the eighth lens, DM11 represents the effective aperture of the object side of the first lens, and DM82 represents the effective aperture of the image side of the eighth lens. By satisfying the above conditions and reasonably setting the thickness and aperture relationship of the first and last lenses, while ensuring that as much light as possible enters the system, the area of light entering the image plane is increased, enabling the lens to have a high relative illumination, and even for weak light such as in the infrared light band, clear imaging ability can be achieved.

[0069] As an embodiment, the eight lenses in the optical lens can all be made of plastic lenses or all made of glass lenses, or a glass-plastic hybrid material combination structure can also be adopted. Specifically, the optical lens adopts eight glass lenses (some lenses are made of low-dispersion glass materials). Due to the low-dispersion characteristics of glass itself, chromatic aberration can be effectively reduced, and it can be ensured that light rays of various wavelengths are actually focused on the same plane, and there is no defocusing in the near-infrared range, thus achieving all-day high-definition imaging day and night. In some embodiments, the first lens and the third lens are glass aspherical lenses, which can effectively reduce costs and correct aberrations, providing optical performance products with higher cost performance.

[0070] The present invention will be further described below with multiple embodiments. In each embodiment, the thickness, curvature radius, and material selection of each lens in the optical lens are somewhat different. For specific differences, refer to the parameter tables of each embodiment. The following embodiments are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited only by the following embodiments. Any other changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be regarded as equivalent replacement methods and are included in the protection scope of the present invention.

[0071] In each embodiment of the present invention, when the lens in the optical lens is an aspherical lens, the aspherical surface profile of the lens all satisfies the following equation:

[0072]

[0073] where z is the sagitta distance from the vertex of the aspherical surface at the position where the height is h along the optical axis direction, c is the paraxial curvature of the surface, k is the conic coefficient, and A 2i is the aspherical surface profile coefficient of the 2i-th order.

[0074] First Embodiment

[0075] Please refer to Figure 1, which shows a schematic diagram of the structure of the optical lens 100 provided in the first embodiment of the present invention. The optical lens 100 includes, along the optical axis from the object side to the imaging plane S18, the following components in sequence: a first lens L1, a second lens L2, a third lens L3, an aperture ST, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a filter G1.

[0076] The first lens L1 has negative optical power, its object-side surface S1 is convex, and its image-side surface S2 is concave. The second lens L2 has negative optical power, its object-side surface S3 is concave, and its image-side surface S4 is concave. The third lens L3 has positive optical power, its object-side surface S5 is convex, and its image-side surface S6 is convex. The fourth lens L4 has positive optical power, its object-side surface S7 is convex, and its image-side surface S8 is convex. The fifth lens L5 has negative optical power, and its object-side surface S9 is concave. The fifth lens has a concave image-side surface; the sixth lens L6 has positive optical power, its object-side surface is convex, and its image-side surface S11 is convex. The fifth lens L5 and the sixth lens L6 form a cemented lens with a cemented surface S10; the seventh lens L7 has positive optical power, its object-side surface S12 is convex, and its image-side surface S13 is convex; the eighth lens L8 has positive optical power, its object-side surface S14 is convex, and its image-side surface S15 is convex; the object-side surface S16 and the image-side surface S17 of the filter G1 are both planar.

[0077] To achieve a smaller lens size and reduce costs, the third lens L3 is a glass aspherical lens, while the first lens L1, the second lens L2, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8 are all glass spherical lenses.

[0078] Specifically, the design parameters of each lens of the optical lens 100 provided in this embodiment are shown in Table 1-1.

[0079] Table 1-1

[0080]

[0081]

[0082] The aspherical surface coefficients of each lens of the optical lens 100 in this embodiment are shown in Table 1-2.

[0083] Table 1-2

[0084] Number kA4A6A8A 10 A12 S1-8.18E-01-7.98E-045.58E-061.82E-082.21E-10-7.99E-12S2-1.14E+00-6.65E-041.88E-05-9.14E-073.69E-08-5.03E- 10S54.84E+003.83E-051.54E-06-1.92E-103.39E-10-5.72E-12S6-1.21E+011.13E-042.35E-063.76E-081.18E-108.56E-12 surface

[0085] Figures 2 and 3 show the MTF curves of the optical lens 100 in this embodiment under visible light (486–656 nm) and infrared light (1500–1700 nm), respectively. These curves represent the lens imaging modulation at different spatial frequencies for each field of view in different wavelength bands. The horizontal axis represents the spatial frequency (unit: period / mm), and the vertical axis represents the MTF value. As can be seen from the figures, in the visible light range, the maximum spatial frequency is 120 line pairs, and the MTF value across the entire field of view is greater than 0.65. In the infrared band, the spatial frequency is also 120 line pairs, and the MTF curves for all fields of view are greater than 0.3, with the MTF values ​​for other fields of view approaching the diffraction limit of the optical system (the curve corresponding to the 0° field of view). This indicates that the optical lens 100 can also achieve good imaging performance in the infrared band. From the MTF curves of the visible light and infrared light of the optical lens described above, it can be concluded that the optical lens 100 of this embodiment can cover a wide spectral range from visible light to near-infrared light, and can maintain high image clarity from visible light during the day to infrared light at night, without the need to adjust the focus between day and night.

[0086] Figure 4 shows the relative illumination curve of the optical lens 100 in this embodiment. It represents the relative illumination value at different image heights on the imaging plane. The horizontal axis represents the field of view angle (unit: degrees), and the vertical axis represents the relative illumination value (unit: %). As can be seen from the figure, the relative illumination value of the optical lens remains above 90% from the center to the maximum edge of the field of view, indicating that the optical lens has high relative illumination.

[0087] Second Embodiment

[0088] The optical lens provided in the second embodiment of the present invention has a structure that is generally the same as that of the optical lens 100 in the first embodiment. The main differences are that the curvature radius, thickness, spacing between lenses, and materials of each lens are different.

[0089] Specifically, the design parameters of each lens in the optical lens provided in this embodiment are shown in Table 2-1.

[0090] Table 2-1

[0091]

[0092] The aspherical surface coefficients of each lens in this embodiment are shown in Table 2-2.

[0093] Table 2-2

[0094] Number kA4A6A8A 10 A 12 S1-8.32E-01-7.48E-046.07E-061.98E-082.28E-10-7.26E-12S2-1.21E+00-5.82E-042.13E-05-9.28E-073.69E-08-4.80E- 10S54.93E+003.83E-051.54E-06-1.92E-103.39E-10-5.72E-12S6-9.44E+001.13E-042.35E-063.76E-081.18E-108.56E-12 surface

[0095] Figures 5 and 6 show the MTF curves of the optical lens in this embodiment under visible light (486–656 nm) and infrared light (1500–1700 nm), respectively. As can be seen from the figures, in the visible light range, the maximum spatial frequency is 120 line pairs, and the MTF value across the entire field of view is greater than 0.35. In the infrared band, the spatial frequency is also 120 line pairs, and the MTF curves for all fields of view approach the diffraction limit of the optical system (the curve corresponding to a 0° field of view), indicating that the optical lens provided in this embodiment can also achieve good imaging results in the infrared band. From the MTF curves of the optical lens in visible and infrared light, it can be concluded that the optical lens of this embodiment can cover a wide spectral range from visible light to near-infrared light, maintaining high image clarity from visible light during the day to infrared light at night, without needing to adjust the focus between day and night.

[0096] Figure 7 shows the relative illumination curve of the optical lens in this embodiment. As can be seen from the figure, the relative illumination value of the optical lens remains above 95% from the center to the maximum edge field of view, indicating that the optical lens in this embodiment has high relative illumination.

[0097] Third Embodiment

[0098] The optical lens provided in the third embodiment of the present invention has a structure that is generally the same as that of the optical lens 100 in the first embodiment. The main differences are that the curvature radius, thickness, spacing between lenses, and materials of each lens are different.

[0099] Specifically, the design parameters of each lens in the optical lens provided in this embodiment are shown in Table 3-2.

[0100] Table 3-2

[0101]

[0102] The aspherical surface coefficients of each lens in this embodiment are shown in Table 3-2.

[0103] Table 3-2

[0104] Number kA4A6A8A 10 A 12 S55.02E+001.97E-052.69E-063.22E-082.44E-094.72E-11S6-1.05E+019.42E-053.24E-069.34E-081.58E-092.74E-10 surface

[0105] Figures 8 and 9 show the MTF curves of the optical lens in this embodiment under visible light (486–656 nm) and infrared light (1500–1700 nm), respectively. As can be seen from the figures, in the visible light range, the maximum spatial frequency is 120 line pairs, and the MTF value across the entire field of view is greater than 0.5. In the infrared band, the spatial frequency is also 120 line pairs, and the MTF curves for all fields of view are greater than 0.25, with the MTF values ​​for other fields of view approaching the diffraction limit of the optical system (the curve corresponding to the 0° field of view). This indicates that the optical lens provided in this embodiment can also achieve good imaging results in the infrared band. From the MTF curves of the optical lens in visible and infrared light, it can be concluded that the optical lens of this embodiment can cover a wide spectral range from visible light to near-infrared light, maintaining high image clarity from visible light during the day to infrared light at night, without needing to adjust the focus between day and night.

[0106] Figure 10 shows the relative illumination curve of the optical lens in this embodiment. As can be seen from the figure, the relative illumination value of the optical lens remains above 88% from the center to the maximum edge field of view, indicating that the optical lens in this embodiment has high relative illumination.

[0107] Please refer to Table 4, which shows the optical characteristics of the optical lenses provided in the above embodiments, including the total optical length TTL, effective focal length f, maximum field of view FOV, image height IH corresponding to the maximum field of view, aperture value Fno, and the relevant values ​​corresponding to each of the aforementioned conditional expressions.

[0108] Table 4

[0109]

[0110]

[0111] In summary, the optical lens provided by this invention employs eight glass lenses. Through specific surface shape combinations and reasonable optical power distribution, it can cover a wide spectral range from visible light to near-infrared light. It can maintain high image clarity from visible light during the day to infrared light at night, without the need to adjust the focus between day and night. At the same time, by using low-dispersion glass lenses, the low dispersion characteristic of glass itself can effectively reduce chromatic aberration and ensure that light of various wavelengths is actually focused on the same plane, with near-infrared light remaining in focus, thereby achieving high-definition imaging all day and night.

[0112] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0113] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An optical lens, comprising eight lenses, characterized in that, It sequentially includes, from the object side to the imaging surface along the optical axis: a first lens with a negative optical power, the object side surface of the first lens being convex and the image side surface of the first lens being concave; a second lens with a negative optical power, the object side surface of the second lens being concave and the image side surface of the second lens being concave; a third lens with a positive optical power, the object side surface of the third lens being convex and the image side surface of the third lens being convex; a fourth lens with a positive optical power, the object side surface of the fourth lens being convex and the image side surface of the fourth lens being convex; a fifth lens with a negative optical power, the object side surface of the fifth lens being concave and the image side surface of the fifth lens being concave; a sixth lens with a positive optical power, the object side surface of the sixth lens being convex and the image side surface of the sixth lens being convex; a seventh lens with a positive optical power, the object side surface of the seventh lens being convex and the image side surface of the seventh lens being convex; an eighth lens with a positive optical power, the object side surface of the eighth lens being convex and the image side surface of the eighth lens being convex; wherein, the optical lens satisfies the conditional formula: 2 < fb / f < 3, fb represents the combined focal length of the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens, and f represents the effective focal length of the optical lens; the working spectral range of the optical lens is 400~1700nm; the optical lens satisfies the conditional formula: 5 < CT23 / CT2 < 7.5, 1.4 < CT23 / CT3 < 2.5; wherein, CT2 represents the central thickness of the second lens, CT3 represents the central thickness of the third lens, and CT23 represents the distance between the second lens and the third lens on the optical axis.

2. The optical lens according to claim 1, characterized in that, The optical lens satisfies the conditional formula: 1.2 < IH / f < 1.5, IH represents the image height corresponding to the maximum field angle of the optical lens.

3. The optical lens according to claim 1, characterized in that, The optical lens satisfies the conditional formula: 1 < BFL / f < 2.5; wherein, BFL represents the back focal length of the optical lens.

4. The optical lens according to claim 1, characterized in that, The optical lens satisfies the conditional formula: -50 < f1 / f < -6, -2 < f2 / f < -0.5; wherein, f1 represents the effective focal length of the first lens and f2 represents the effective focal length of the second lens.

5. The optical lens according to claim 1, characterized in that, The optical lens satisfies the conditional formula: 1 < f3 / f < 5, 1 < f4 / f < 5; wherein, f3 represents the effective focal length of the third lens and f4 represents the effective focal length of the fourth lens.

6. The optical lens according to claim 1, characterized in that, The fifth lens and the sixth lens form a cemented lens, and the optical lens satisfies the conditional formula: -8 < f56 / f < -2, -0.8 < f5 / f6 < -0.4; wherein, f5 represents the effective focal length of the fifth lens, f6 represents the effective focal length of the sixth lens, and f56 represents the combined focal length of the fifth lens and the sixth lens.

7. The optical lens according to claim 1, characterized in that, The optical lens satisfies the conditional formula: 5 < f7 / f < 50, 2 < f8 / f < 5; wherein, f7 represents the effective focal length of the seventh lens and f8 represents the effective focal length of the eighth lens.

8. The optical lens according to claim 1, characterized in that, The optical lens satisfies the conditional formula: 3 < f1 / f2 < 50; where, f1 represents the effective focal length of the first lens, and f2 represents the effective focal length of the second lens.

9. The optical lens according to claim 1, characterized in that, The optical lens satisfies the conditional formula: 0.3 < f3 / f4 < 0.95; where, f3 represents the effective focal length of the third lens, and f4 represents the effective focal length of the fourth lens.

10. The optical lens according to claim 1, characterized in that, The optical lens satisfies the conditional formula: -2 < fa / fb < 2; where, fa represents the combined focal length of the first lens, the second lens, and the third lens, and fb represents the combined focal length of the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens.

11. The optical lens according to claim 1, characterized in that, The optical lens satisfies the conditional formulas: 0.4 < CT1 / CT8 < 0.8, 1.2 < DM11 / DM82 < 2; where, CT1 represents the central thickness of the first lens, CT8 represents the central thickness of the eighth lens, DM11 represents the effective aperture of the object side of the first lens, and DM82 represents the effective aperture of the image side of the eighth lens.

12. The optical lens according to claim 1, characterized in that, The optical lens satisfies the conditional formulas: 1.8 < CT3 / CT4 < 3.0, 1.5 < DM31 / DM41 < 3; where, CT3 represents the central thickness of the third lens, CT4 represents the central thickness of the fourth lens, DM31 represents the effective aperture of the object side of the third lens, and DM41 represents the effective aperture of the object side of the fourth lens.

Images