Optical lens

Abstract

This invention provides an optical lens composed of eight lenses, arranged sequentially along the optical axis from the object side to the image plane: a first lens with negative optical power, its object side being convex and its image side being concave; a second lens with negative optical power, its object side being concave and its image side being convex; a third lens with negative optical power, its object side being concave and its image side being convex; a fourth lens with positive optical power; a fifth lens with negative optical power, its object side being concave near the optical axis and its image side being concave; a sixth lens with positive optical power, its object side being convex and its image side being convex; a seventh lens with negative optical power, its object side being concave; and an eighth lens with positive optical power. The optical lens provided by this invention can reduce aberrations, improve image quality, and give the lens one or more advantages such as a large field of view, a large aperture, miniaturization, and high image quality.

Description

Technical Field

[0001] The present invention relates to the technical field of imaging lenses, and particularly to an optical lens. Background Art

[0002] Law enforcement cameras are mainly used for digitally recording the on-site situations during law enforcement processes, such as video recording, photographing, audio recording, etc., so as to provide effective on-site image materials afterwards. During on-site law enforcement, law enforcement officers need to record a large range and clear images. However, the lenses of law enforcement cameras on the market either record images unclearly or have too small field angles and cannot record too many pictures.

[0003] Therefore, how to make the lens of a law enforcement camera meet high imaging quality is an urgent problem to be solved at present. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide an optical lens, which has the advantage of excellent imaging quality.

[0005] The technical solution adopted by the present invention is as follows: An optical lens, the number of lenses with optical power is eight, and sequentially includes from the object side to the imaging surface along the optical axis: A first lens with negative optical power, its object side is convex, and its image side is concave; A second lens with negative optical power, its object side is concave, and its image side is convex; A third lens with negative optical power, its object side is concave, and its image side is convex; A fourth lens with positive optical power; A fifth lens with negative optical power, its object side is concave near the optical axis, and its image side is concave; A sixth lens with positive optical power, its object side is convex, and its image side is convex; A seventh lens with negative optical power, its object side is concave; An eighth lens with positive optical power; Wherein, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: -27 < f2 / f < -8; the curvature radius R3 of the object side of the second lens and the curvature radius R4 of the image side of the second lens satisfy: -0.55 < (R3 - R4) / (R3 + R4) < -0.15.

[0006] Further preferably, the optical lens satisfies one or more of the following conditional expressions: The total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 6.5 < TTL / f < 7.5; The total optical length TTL of the optical lens and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: 2.7 < TTL / IH < 2.8.

[0007] Further preferably, the optical lens satisfies one or more of the following conditional expressions: The true image height IH corresponding to the maximum field angle of the optical lens and the effective focal length f of the optical lens satisfy: 2.4 < IH / f < 2.7; The total optical length TTL of the optical lens, the true image height IH corresponding to the maximum field angle of the optical lens, and the maximum field angle FOV of the optical lens satisfy: 0.06 < 1°×TTL / (IH / 2) / (FOV / 2) < 0.08.

[0008] Further preferably, the optical lens satisfies one or more of the following conditional expressions: The clear aperture radius d1 of the object side of the first lens, the true image height IH corresponding to the maximum field angle of the optical lens, and the maximum field angle FOV of the optical lens satisfy: 0.21 < d1 / (IH / 2) / tan(FOV / 2) < 0.24; The true image height IH corresponding to the maximum field angle of the optical lens, the effective focal length f of the optical lens, and the radian value θ of the maximum half field angle of the optical lens satisfy: 0.9 < (IH / 2) / (f×θ) < 0.93.

[0009] Further preferably, the optical lens satisfies one or more of the following conditional expressions: The effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -1.8 < f1 / f < -1.3; The effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: -26 < f3 / f < -11.

[0010] Further preferably, the optical lens satisfies one or more of the following conditional expressions: The effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 1.6 < f4 / f < 2.3; The radius of curvature R7 of the object side of the fourth lens and the radius of curvature R8 of the image side of the fourth lens satisfy: 0.05 < R7 / R8 < 28.

[0011] Further preferably, the optical lens satisfies one or more of the following conditional expressions: The effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -15 < f5 / f < -6; The effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: 1 < f6 / f < 1.3; The effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: -1.2 < f7 / f < -0.9; The effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: 2.1 < f8 / f < 3.5.

[0012] Further preferably, the optical lens satisfies one or more of the following conditional expressions: The combined focal length f1234 of the first lens, the second lens, the third lens, and the fourth lens and the effective focal length f of the optical lens satisfy: 1.7 < f1234 / f < 2.3; The focal length f2 of the second lens and the combined focal length f1234 of the first lens, the second lens, the third lens, and the fourth lens satisfy: -13 < f2 / f1234 < -4.2.

[0013] Further preferably, the optical lens satisfies one or more of the following conditional expressions: The focal length f2 of the second lens and the focal length f3 of the third lens satisfy: 0.45 < f2 / f3 < 1.2; The radius of curvature R3 of the object side surface of the second lens and the effective focal length f of the optical lens satisfy: -5.5 < R3 / f < -1.15; The radius of curvature R4 of the image side surface of the second lens and the effective focal length f of the optical lens satisfy: -16.5 < R4 / f < -1.7; The radius of curvature R5 of the object side surface of the third lens and the effective focal length f of the optical lens satisfy: -5 < R5 / f < -1.1; The radius of curvature R6 of the image side surface of the third lens and the effective focal length f of the optical lens satisfy: -8.5 < R6 / f < -1.5.

[0014] Further preferably, the optical lens satisfies one or more of the following conditional expressions: The focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: -25.27 < f2 / f < -8.29; The radius of curvature R3 of the object side surface of the second lens and the radius of curvature R4 of the image side surface of the second lens satisfy: -0.52 < (R3 - R4) / (R3 + R4) < -0.17.

[0015] Compared with the prior art, the optical lens provided by the present invention adopts eight lenses with specific optical powers. Through specific surface shape combinations and reasonable optical power distributions, it can improve the imaging quality of the optical lens, reduce aberrations, and enhance the imaging quality of the optical lens, enabling the lens to have one or more advantages such as a large viewing angle, a large aperture, miniaturization, and high imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the optical lens in Embodiment 1 of the present invention.

[0017] Figure 2 This is a field curvature curve diagram of the optical lens in Embodiment 1 of the present invention.

[0018] Figure 3 This is an F-Theta distortion curve of the optical lens in Embodiment 1 of the present invention.

[0019] Figure 4 This is an axial aberration curve of the optical lens in Embodiment 1 of the present invention.

[0020] Figure 5 This is a chromatic aberration curve of the optical lens in Embodiment 1 of the present invention.

[0021] Figure 6 This is an MTF curve of the optical lens in Embodiment 1 of the present invention.

[0022] Figure 7 This is a relative illumination curve of the optical lens in Embodiment 1 of the present invention.

[0023] Figure 8 This is a schematic diagram of the optical lens structure in Embodiment 2 of the present invention.

[0024] Figure 9 This is a field curvature curve diagram of the optical lens in Embodiment 2 of the present invention.

[0025] Figure 10 This is the F-Theta distortion curve of the optical lens in Embodiment 2 of the present invention.

[0026] Figure 11 This is an axial aberration curve of the optical lens in Embodiment 2 of the present invention.

[0027] Figure 12 This is a chromatic aberration curve of the optical lens in Embodiment 2 of the present invention.

[0028] Figure 13 This is the MTF curve of the optical lens in Embodiment 2 of the present invention.

[0029] Figure 14 This is a relative illumination curve of the optical lens in Embodiment 2 of the present invention.

[0030] Figure 15 This is a schematic diagram of the optical lens in Embodiment 3 of the present invention.

[0031] Figure 16This is a field curvature curve diagram of the optical lens in Embodiment 3 of the present invention.

[0032] Figure 17 This is the F-Theta distortion curve of the optical lens in Embodiment 3 of the present invention.

[0033] Figure 18 This is an axial aberration curve of the optical lens in Embodiment 3 of the present invention.

[0034] Figure 19 This is a chromatic aberration curve of the optical lens in Embodiment 3 of the present invention.

[0035] Figure 20 This is an MTF curve of the optical lens in Embodiment 3 of the present invention.

[0036] Figure 21 This is a relative illumination curve of the optical lens in Embodiment 3 of the present invention.

[0037] Figure 22 This is a schematic diagram of the optical lens structure in Embodiment 4 of the present invention.

[0038] Figure 23 This is a field curvature curve diagram of the optical lens in Embodiment 4 of the present invention.

[0039] Figure 24 This is the F-Theta distortion curve of the optical lens in Embodiment 4 of the present invention.

[0040] Figure 25 This is an axial aberration curve of the optical lens in Embodiment 4 of the present invention.

[0041] Figure 26 This is a chromatic aberration curve of the optical lens in Embodiment 4 of the present invention.

[0042] Figure 27 This is the MTF curve of the optical lens in Embodiment 4 of the present invention.

[0043] Figure 28 This is a relative illumination curve of the optical lens in Embodiment 4 of the present invention.

[0044] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0045] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly so specified herein.

[0051] 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.

[0052] The optical lens provided by the embodiment of the present invention has eight lenses with optical powers. They are, in order from the object side to the imaging surface along the optical axis, 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.

[0053] In some embodiments, the first lens may have a negative optical power. Its object side is convex, and its image side is concave. The second lens may have a negative optical power. Its object side is concave, and its image side is convex. The third lens may have a negative optical power. Its object side is concave, and its image side is convex. The fourth lens may have a positive optical power. Its object side may be concave or convex, and its image side may be concave or convex. The fifth lens may have a negative optical power. Its object side is concave near the optical axis, and its image side is concave. The sixth lens may have a positive optical power. Its object side is convex, and its image side is convex. The seventh lens may have a negative optical power. Its object side is concave, and its image side may be concave or convex. The eighth lens may have a positive optical power. Its object side may be concave or convex, and its image side may be concave or convex.

[0054] In some embodiments, the optical lens may further include an aperture. The aperture may be located between the fourth lens and the fifth lens. It can be understood that the aperture can be used to limit the amount of incident light to change the brightness of the imaging.

[0055] In some embodiments, the optical lens may further include a filter. The filter may be disposed between the eighth lens and the imaging surface. The filter is used to filter out interfering light to prevent the interfering light from reaching the imaging surface of the optical lens and affecting normal imaging.

[0056] In some embodiments, the sixth lens and the seventh lens may be glued together to form a cemented lens, which can effectively correct the chromatic aberration of the optical lens, reduce the eccentricity sensitivity of the optical lens, balance the aberration of the optical lens, and improve the imaging quality of the optical lens; it can also reduce the assembly sensitivity of the optical lens, thereby reducing the processing difficulty of the optical lens and improving the assembly yield of the optical lens.

[0057] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: -27 < f2 / f < -8. Meeting the above range can enable the second lens to have an appropriate negative optical power, further expand the field angle of the optical lens, and balance and share the negative optical power at the front end of the optical lens. More specifically, -25.27 < f2 / f < -8.29.

[0058] In some embodiments, the radius of curvature R3 of the object side surface of the second lens and the radius of curvature R4 of the image side surface of the second lens satisfy: -0.55 < (R3 - R4) / (R3 + R4) < -0.15. Satisfying the above range can correct the aberration of the optical lens, ensure the smooth light path passing through the second lens, reduce the tolerance sensitivity of the optical lens, and facilitate the smooth entry of light into the rear lens. More specifically, -0.52 < (R3 - R4) / (R3 + R4) < -0.17.

[0059] In some embodiments, the overall optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 6.5 < TTL / f < 7.5; the overall optical length TTL of the optical lens and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: 2.7 < TTL / IH < 2.8. Satisfying the above range helps to balance the overall length and volume of the optical lens by reasonably controlling the overall length, focal length, and image height of the optical lens, and is beneficial to improving the structural stability of the optical lens. More specifically, 6.95 < TTL / f < 7.06, 2.73 < TTL / IH < 2.86.

[0060] In some embodiments, the true image height IH corresponding to the maximum field angle of the optical lens and the effective focal length f of the optical lens satisfy: 2.4 < IH / f < 2.7. Satisfying the above range can reasonably control the image height and focal length of the optical lens, provide a balance between the image height and focal length for the optical lens, and help to improve the imaging quality. More specifically, 2.52 < IH / f < 2.58.

[0061] In some embodiments, the overall optical length TTL of the optical lens, the true image height IH corresponding to the maximum field angle of the optical lens, and the maximum field angle FOV of the optical lens satisfy: 0.06 < 1°×TTL / (IH / 2) / (FOV / 2) < 0.08. Satisfying the above range helps to control the structural balance of the overall length, field angle, and image height of the optical lens, and makes the structure of the optical lens more stable on the premise of meeting the design requirements.

[0062] In some embodiments, the clear aperture radius d1 of the object side surface of the first lens, the true image height IH corresponding to the maximum field angle of the optical lens, and the maximum field angle FOV of the optical lens satisfy: 0.21 < d1 / (IH / 2) / tan(FOV / 2) < 0.24. Satisfying the above range can reasonably control the front aperture while meeting the requirements of the optical lens having a large field angle and a large image height, which is beneficial to the miniaturization of the optical lens.

[0063] In some embodiments, the true image height IH corresponding to the maximum field angle of the optical lens, the effective focal length f of the optical lens, and the radian value θ of the maximum half-field angle of the optical lens satisfy: 0.9 < (IH / 2) / (f×θ) < 0.93. Meeting the above range helps to keep the distortion of the optical lens within a reasonable range, makes the picture ratio of each field in the final imaging plane relatively harmonious, and improves the imaging quality.

[0064] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -1.8 < f1 / f < -1.3. Meeting the above range enables the first lens to have a strong negative optical power, captures light rays with a large field angle, and is beneficial for the optical lens to have the characteristic of a large field angle. More specifically, -1.67 < f1 / f < -1.4.

[0065] In some embodiments, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: -26 < f3 / f < -11. Meeting the above range makes the third lens have an appropriate negative optical power, which helps to reduce astigmatism. More specifically, -24.61 < f3 / f < -11.58.

[0066] In some embodiments, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 1.6 < f4 / f < 2.3. Meeting the above range makes the fourth lens have an appropriate positive optical power, which helps to balance the overall focal length at the front end of the optical lens, improve the stability of the optical lens, and can reasonably converge light rays to prepare for the aberration correction of the rear-end lens. More specifically, 1.75 < f4 / f < 2.14.

[0067] In some embodiments, the curvature radius R7 of the object side surface of the fourth lens and the curvature radius R8 of the image side surface of the fourth lens satisfy: 0.05 < R7 / R8 < 28. Meeting the above range helps to control the shapes of the object side surface and the image side surface of the fourth lens reasonably and reduces the processing difficulty. More specifically, 0.06 < R7 / R8 < 25.54.

[0068] In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -15 < f5 / f < -6. Meeting the above range helps the fifth lens to have an appropriate negative optical power and can appropriately reduce spherical aberration and coma. More specifically, -13.69 < f5 / f < -6.69.

[0069] In some embodiments, the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: 1 < f6 / f < 1.3. Meeting the above range helps the sixth lens to have an appropriate positive optical power and balance the field curvature and astigmatism of the optical lens. More specifically, 1.11 < f6 / f < 1.19.

[0070] In some embodiments, the effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: -1.2 < f7 / f < -0.9. Meeting the above range helps the seventh lens to have an appropriate negative optical power, enabling reasonable control of the smooth light trend at the rear end of the optical lens and reducing aberration. More specifically, -1.09 < f7 / f < -0.96.

[0071] In some embodiments, the effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: 2.1 < f8 / f < 3.5. Meeting the above range enables the eighth lens to have an appropriate positive optical power, which helps to reasonably control the angle of light entering the rear-end chip and reduces the eccentricity sensitivity of the chip. More specifically, 2.3 < f8 / f < 3.21.

[0072] In some embodiments, the combined focal length f1234 of the first lens, the second lens, the third lens, and the fourth lens and the effective focal length f of the optical lens satisfy: 1.7 < f1234 / f < 2.3; the focal length f2 of the second lens and the combined focal length f1234 of the first lens, the second lens, the third lens, and the fourth lens satisfy: -13 < f2 / f1234 < -4.2. Meeting the above range makes the front end of the optical lens have an appropriate positive optical power as a whole, and enables large-angle light entering the lens to be fully transmitted to the rear light system, obtaining a larger field of view and higher relative illumination. More specifically, 1.82 < f1234 / f < 2.14; -12.62 < f2 / f1234 < -4.53.

[0073] In some embodiments, the focal length f2 of the second lens and the focal length f3 of the third lens satisfy: 0.45 < f2 / f3 < 1.2. Meeting the above range can reasonably control the ratio of the focal lengths of the second lens and the third lens, which is beneficial to the smooth transition of light and can balance various aberrations generated by the optical lens, improving the imaging quality of the optical lens. More specifically, 0.48 < f2 / f3 < 1.08.

[0074] In some embodiments, the radius of curvature R3 of the object side of the second lens and the effective focal length f of the optical lens satisfy: -5.5 < R3 / f < -1.15; the radius of curvature R4 of the image side of the second lens and the effective focal length f of the optical lens satisfy: -16.5 < R4 / f < -1.7. Meeting the above range helps to control the incident angle and the exit angle of light entering and leaving the second lens, making the light trend gentle and reducing the difficulty of aberration correction for the rear-end lens. More specifically, -5.19 < R3 / f < -1.16; -15.18 < R4 / f < -1.83.

[0075] In some embodiments, the radius of curvature R5 of the object side surface of the third lens and the effective focal length f of the optical lens satisfy: -5 < R5 / f < -1.1; the radius of curvature R6 of the image side surface of the third lens and the effective focal length f of the optical lens satisfy: -8.5 < R6 / f < -1.5. Satisfying the above ranges helps to control the incident angle and exit angle of light entering and leaving the third lens, making the light path gentle and reducing the difficulty of aberration correction for the rear lens. More specifically, -4.71 < R5 / f < -1.24; -7.86 < R6 / f < -1.64.

[0076] In some embodiments, the true image height IH corresponding to the maximum field angle of the optical lens and the entrance pupil diameter EPD of the optical lens satisfy: 5 < IH / EPD < 5.2. Satisfying the above range is beneficial to increasing the light transmission amount and improving the relative illumination. More specifically, 5.05 < IH / EPD < 5.16.

[0077] In some embodiments, the distance BL on the optical axis from the image side surface of the eighth lens to the imaging surface and the effective focal length f of the optical lens satisfy: 0.8 < BL / f < 1.5. Satisfying the above range can endow the optical lens with the characteristic of long back focus, meet the arrangement requirements of the rear-end chip, and reduce the assembly and processing difficulty. More specifically, 0.84 < BL / f < 1.36.

[0078] In some embodiments, the effective focal length f of the optical lens, the maximum field angle FOV of the optical lens, and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: 60° < f×FOV / IH < 65°. Satisfying the above range, by reasonably restricting the relationship between the focal length, field angle and image height of the optical lens, is beneficial to achieving the balance of large field angle and large target surface imaging of the optical lens. More specifically, 62.18° < f×FOV / IH < 63.22°.

[0079] In some embodiments, the combined focal length f5678 of the fifth lens, the sixth lens, the seventh lens and the eighth lens and the effective focal length f of the optical lens satisfy: 2.6 < f5678 / f < 3.8. Satisfying the above range can make the overall rear end of the optical lens have a strong positive optical power, effectively transmit more light beams to the imaging surface, and can reduce the deviation of the incident angle and exit angle of light in different fields of view. More specifically, 2.87 < f5678 / f < 3.46.

[0080] In some embodiments, the combined focal length f67 of the sixth lens and the seventh lens and the effective focal length f of the optical lens satisfy: 8 < f67 / f < 16. Meeting the above range, by combining two lenses with positive and negative optical powers, the aberrations generated by each other can be canceled out, and the chromatic aberration of the optical imaging system can be effectively corrected by setting the positive and negative lenses in the cemented lens and setting the combined focal length of the positive and negative lenses, thereby improving the resolution ability of the system. More specifically, 8.73 < f67 / f < 15.04.

[0081] In some embodiments, the combined focal length f1234 of the first lens, the second lens, the third lens, and the fourth lens and the combined focal length f5678 of the fifth lens, the sixth lens, the seventh lens, and the eighth lens satisfy: 0.5 < f1234 / f5678 < 0.8. Meeting the above range, by reasonably setting the optical powers of the lens groups before and after the aperture, it is beneficial to balance the distortion and astigmatism generated by the front and rear end lenses of the optical lens and improve the imaging quality of the optical lens. More specifically, 0.54 < f1234 / f5678 < 0.71.

[0082] In some embodiments, the combined focal length f67 of the sixth lens and the seventh lens and the combined focal length f5678 of the fifth lens, the sixth lens, the seventh lens, and the eighth lens satisfy: 2.3 < f67 / f5678 < 5. Meeting the above range can make the proportion of the focal length of the cemented lens in the rear-end lens more appropriate and further improve the chromatic aberration correction ability of the optical lens. More specifically, 2.52 < f67 / f5678 < 4.66.

[0083] In some embodiments, the optical lens satisfies the conditional expressions: 2.2 mm < f < 2.5 mm, 1.1 mm < EPD < 1.3 mm, 16 mm < TTL < 17 mm, 1.8 < Fno < 2.2, 12° < CRA < 14°, 1.9 mm < BL < 3.3 mm, 150° < FOV < 170°, 5.5 mm < IH < 6.5 mm; where f represents the effective focal length of the optical lens, EPD represents the entrance pupil diameter of the optical lens, TTL represents the overall optical length of the optical lens, Fno represents the f-number of the optical lens, CRA represents the chief ray angle of incidence at the maximum image height of the optical lens, BL represents the distance from the image side of the eighth lens to the imaging plane on the optical axis, FOV represents the maximum field angle of the optical lens, and IH represents the true image height corresponding to the maximum field angle of the optical lens. Meeting the above conditions indicates that the optical lens provided by the embodiments of the present invention has at least the characteristics of miniaturization, large field angle, large aperture, and high imaging quality. More specifically, 2.32 mm < f < 2.38 mm, 1.16 mm < EPD < 1.2 mm, 16.43 mm < TTL < 16.51 mm, 1.9 < Fno < 2.1, 12.19° < CRA < 13.78°, 1.99 mm < BL < 3.19 mm, 159° < FOV < 161°, 5.9 mm < IH < 6.1 mm.

[0084] In some embodiments, the lens material of the optical lens provided by the present invention can be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. On the other hand, when the lens material is glass, the geometric chromatic aberration of the optical system can be effectively corrected by the low dispersion characteristic of the glass itself. The first lens, the third lens, the fourth lens, the sixth lens, the seventh lens, and the eighth lens in the optical lens provided by the present invention adopt glass lenses, and the second lens and the fifth lens adopt plastic lenses.

[0085] In some embodiments, 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 can adopt spherical lenses or aspherical lenses. Compared with the spherical structure, the aspherical structure can effectively reduce the aberration of the optical system, thereby reducing the number of lenses and the size of the lenses, and better realizing the miniaturization of the lens. More specifically, the second lens, the fourth lens, the fifth lens, and the eighth lens of the present invention adopt aspherical lenses, and the first lens, the third lens, the sixth lens, and the seventh lens adopt spherical lenses.

[0086] In each embodiment of the present invention, when the lens adopts an aspherical lens, the shapes of the aspherical surfaces of the optical lens satisfy the following equation: ; Where z is the distance between the surface and the vertex of the surface in the direction of the optical axis, h is the distance from the optical axis to the surface, c is the curvature of the vertex of the surface, K is the quadratic surface coefficient, and B, C, D, E, and F are the fourth, sixth, eighth, tenth, and twelfth order surface coefficients, respectively.

[0087] The present invention will be further described below with reference to several embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens are different; for specific differences, please refer to the parameter tables of each embodiment. The following embodiments are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention.

[0088] Example 1 Please see Figure 1 The diagram shown is a structural schematic of the optical lens 100 provided in Embodiment 1 of the present invention. The optical lens includes, in sequence along the optical axis from the object side to the imaging plane: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a filter G1.

[0089] Among them, the first lens L1 has negative optical power, its object side S1 is convex, and its image side S2 is concave. The second lens L2 has negative optical power, its object side S3 is concave, and its image side S4 is convex. The third lens L3 has negative optical power, its object side S5 is concave, and its image side S6 is convex. The fourth lens L4 has positive optical power, its object side S7 is concave near the optical axis, and its image side S8 is convex. The fifth lens L5 has negative optical power, its object side S9 is concave near the optical axis, and its image side S10 is concave. The sixth lens L6 has positive optical power, its object-side surface S11 is convex, and its image-side surface is convex. The seventh lens L7 has negative optical power, its object side is concave, and its image side S13 is concave. The sixth lens L6 and the seventh lens L7 form a cemented lens group with positive optical power, that is, the cemented surface of the image side of the sixth lens L6 and the object side of the seventh lens L7 is S12. The eighth lens L8 has positive optical power, its object side S14 is convex, and its image side S15 is convex.

[0090] The object-side surface S16 and the image-side surface S17 of filter G1 are both planar. The imaging plane S18 is a plane.

[0091] The first lens L1, the third lens L3, the sixth lens L6 and the seventh lens L7 are all glass spherical lenses, the fourth lens L4 and the eighth lens L8 are glass aspherical lenses, and the second lens L2 and the fifth lens L5 are plastic aspherical lenses.

[0092] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0093] Table 1-1 The surface profile parameters of the aspherical lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0094] Table 1-2 Figure 2 The field curvature curve of Example 1 is shown, which represents the degree of curvature of light of different wavelengths in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within -0.02 mm to 0.04 mm, indicating that the optical lens can effectively correct the field curvature.

[0095] Figure 3 The diagram shows the F-Theta distortion curve of the optical lens 100 in this embodiment, which represents the distortion at different field-of-view angles on the imaging plane. The horizontal axis represents the distortion value (unit: %), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the F-Theta distortion of the optical lens is controlled within -8% to 0, and the image compression in the edge angle region is relatively smooth, effectively improving the sharpness of the unfolded image, indicating that the optical lens 100 can correct distortion well.

[0096] Figure 4 The diagram shows the axial aberration curve of the optical lens 100 in this embodiment, which represents the aberration of each wavelength on the optical axis at the imaging plane. The horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. As can be seen from the figure, the axial aberration offset is controlled within ±0.02 mm, indicating that the optical lens 100 can correct axial aberration well.

[0097] Figure 5The diagram shows the transverse chromatic aberration curve of the optical lens 100 in this embodiment. It represents the chromatic aberration of each wavelength relative to the center wavelength (0.555 μm) at different image heights on the imaging plane. The horizontal axis represents the transverse chromatic aberration value of each wavelength relative to the center wavelength (unit: μm), and the vertical axis represents the normalized field of view. As can be seen from the figure, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within 0~4 μm, indicating that the optical lens 100 can effectively correct chromatic aberration.

[0098] Figure 6 The modulation transfer function (MTF) curve of the optical lens 100 in this embodiment is shown, which represents the lens imaging modulation at different spatial frequencies in each field of view. The horizontal axis represents the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. As can be seen from the figure, the MTF value of this embodiment is above 0.3 throughout the entire field of view. The MTF curve decreases smoothly and evenly from the center to the edge of the field of view, exhibiting good imaging quality and good detail resolution at both low and high frequencies.

[0099] Figure 7 The relative illumination curve of the optical lens 100 in this embodiment is shown, which represents the relative illumination value at different field-of-view angles on the imaging plane. The horizontal axis represents the half-field angle (unit: °), and the vertical axis represents the relative illumination (unit: %). As can be seen from the figure, the relative illumination value of the optical lens is still greater than 70% at the maximum half-field angle, indicating that the optical lens 100 has good relative illumination.

[0100] Example 2 Please see Figure 8 The figure shows a schematic diagram of the structure of the optical lens 200 provided in Embodiment 2 of the present invention. The main difference between this embodiment and Embodiment 1 is that the object side surface S7 of the fourth lens L4 is a convex surface; the image side surface S8 of the fourth lens L4 is a concave surface; and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0101] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0102] Table 2-1 The surface profile parameters of the aspherical lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0103] Table 2-2 In this embodiment, the field curvature curve, F-Theta distortion curve, axial aberration curve, transverse chromatic aberration curve, MTF curve, and relative illumination diagram of the optical lens 200 are respectively as follows: Figures 9 to 14 As shown.

[0104] from Figure 9 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.02mm to 0.03mm, indicating that the optical lens can effectively correct the field curvature.

[0105] from Figure 10 As can be seen, the F-Theta distortion of the optical lens is controlled within -10% to 0, and the image compression in the edge angle area is relatively smooth, which effectively improves the clarity of the unfolded image, indicating that the optical lens 200 can correct distortion well.

[0106] from Figure 11 As can be seen, the axial aberration offset is controlled within ±0.02mm, indicating that the optical lens 200 can effectively correct axial aberration.

[0107] from Figure 12 As can be seen, the chromatic aberration of the longest and shortest wavelengths is controlled within 0~2μm, indicating that the optical lens 200 can correct chromatic aberration well.

[0108] from Figure 13 As can be seen, the MTF value of this embodiment is above 0.4 throughout the entire field of view. The MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good imaging quality and good detail resolution in both low and high frequency conditions.

[0109] from Figure 14 As can be seen, the relative illumination value of the optical lens is still greater than 70% at the maximum half field of view, indicating that the optical lens 200 has good relative illumination.

[0110] Example 3 Please see Figure 15 The figure shows a schematic diagram of the structure of the optical lens 300 provided in Embodiment 3 of the present invention. The main difference between this embodiment and Embodiment 1 is that: the object side S7 of the fourth lens L4 is a convex surface; the image side S8 of the fourth lens L4 is a concave surface; the image side S13 of the seventh lens L7 is a convex surface; the image side S15 of the eighth lens L8 is a concave surface; and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0111] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0112] Table 3-1 The surface profile parameters of the aspherical lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0113] Table 3-2 In this embodiment, the field curvature curve, F-Theta distortion curve, axial aberration curve, transverse chromatic aberration curve, MTF curve, and relative illumination diagram of the optical lens 300 are respectively as follows: Figures 16 to 21 As shown.

[0114] from Figure 16 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.03mm to 0.04mm, indicating that the optical lens can effectively correct the field curvature.

[0115] from Figure 17 As can be seen, the F-Theta distortion of the optical lens is controlled within -10% to 0, and the image compression in the edge angle area is relatively smooth, which effectively improves the clarity of the unfolded image, indicating that the optical lens 300 can correct distortion well.

[0116] from Figure 18 As can be seen, the axial aberration offset is controlled within ±0.02mm, indicating that the optical lens 300 can effectively correct axial aberration.

[0117] from Figure 19 As can be seen, the chromatic aberration of the longest and shortest wavelengths is controlled within -2μm to 4μm, indicating that the optical lens 300 can correct chromatic aberration well.

[0118] from Figure 20 As can be seen, the MTF value of this embodiment is above 0.3 throughout the entire field of view. The MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good imaging quality and good detail resolution in both low and high frequency conditions.

[0119] from Figure 21 As can be seen, the relative illumination value of the optical lens is still greater than 75% at the maximum half field of view, indicating that the optical lens 300 has good relative illumination.

[0120] Example 4 Please see Figure 22 The figure shows a schematic diagram of the structure of the optical lens 400 provided in Embodiment 4 of the present invention. The main differences between this embodiment and Embodiment 1 are: the object side S7 of the fourth lens L4 is a convex surface; the image side S8 of the fourth lens L4 is a concave surface; the image side S13 of the seventh lens L7 is a convex surface; the object side S14 of the eighth lens L8 is a concave surface; and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0121] The relevant parameters of each lens in the optical lens 400 in Example 4 are shown in Table 4-1.

[0122] Table 4-1 The surface profile parameters of the aspherical lens of the optical lens 400 in Example 4 are shown in Table 4-2.

[0123] Table 4-2 In this embodiment, the field curvature curve, F-Theta distortion curve, axial aberration curve, transverse chromatic aberration curve, MTF curve, and relative illumination diagram of the optical lens 400 are respectively as follows: Figures 23 to 28 As shown.

[0124] from Figure 23 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.04mm to 0.03mm, indicating that the optical lens can effectively correct the field curvature.

[0125] from Figure 24 As can be seen, the F-Theta distortion of the optical lens is controlled within -10% to 0, and the image compression in the edge angle area is relatively smooth, which effectively improves the clarity of the unfolded image, indicating that the optical lens 400 can correct distortion well.

[0126] from Figure 25 As can be seen, the axial aberration offset is controlled within ±0.02mm, indicating that the optical lens 400 can correct axial aberration well.

[0127] from Figure 26 As can be seen, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within -2μm to 4μm, indicating that the optical lens 400 can correct chromatic aberration well.

[0128] from Figure 27 As can be seen, the MTF value of this embodiment is above 0.35 throughout the entire field of view. The MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good imaging quality and good detail resolution in both low and high frequency conditions.

[0129] from Figure 28 As can be seen, the relative illumination value of the optical lens is still greater than 70% at the maximum half field of view, indicating that the optical lens 400 has good relative illumination.

[0130] Please refer to Table 5 for the optical characteristics corresponding to each of the above embodiments, including the effective focal length f, total optical length TTL, aperture value Fno, true image height IH corresponding to the maximum field of view, principal ray incident angle CRA at the maximum image height, maximum field of view FOV, distance BL from the image side of the eighth lens to the imaging plane on the optical axis, and the numerical values ​​corresponding to each conditional expression in each embodiment.

[0131] Table 5 In summary, the optical lens provided by the present invention employs eight lenses with specific optical power. Through specific surface shape matching and reasonable optical power distribution, it can improve the imaging quality of the optical lens, reduce aberrations, and enhance the imaging quality of the optical lens, giving the lens one or more advantages such as a large field of view, a large aperture, miniaturization, and high imaging quality.

[0132] 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.

[0133] 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 having optical power, 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, whose object side is convex and whose image side is concave; A second lens with a negative optical power, whose object side is concave and whose image side is convex; A third lens with a negative optical power, whose object side is concave and whose image side is convex; A fourth lens with a positive optical power; A fifth lens with a negative optical power, whose object side is concave near the optical axis and whose image side is concave; A sixth lens with a positive optical power, whose object side is convex and whose image side is convex; A seventh lens with a negative optical power, whose object side is concave; An eighth lens with a positive optical power; Wherein, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: -27 < f2 / f < -8; the curvature radius R3 of the object side of the second lens and the curvature radius R4 of the image side of the second lens satisfy: -0.55 < (R3 - R4) / (R3 + R4) < -0.

15.

2. The optical lens according to claim 1, characterized in that, The optical lens satisfies one or more of the following conditional expressions: The overall optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 6.5 < TTL / f < 7.5; the overall optical length TTL of the optical lens and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: 2.7 < TTL / IH < 2.

8.

3. The optical lens according to claim 1, characterized in that, The optical lens satisfies one or more of the following conditional expressions: The true image height IH corresponding to the maximum field angle of the optical lens and the effective focal length f of the optical lens satisfy: 2.4 < IH / f < 2.7; the overall optical length TTL of the optical lens, the true image height IH corresponding to the maximum field angle of the optical lens, and the maximum field angle FOV of the optical lens satisfy: 0.06 < 1°×TTL / (IH / 2) / (FOV / 2) < 0.

08.

4. The optical lens according to claim 1, characterized in that, The optical lens satisfies one or more of the following conditional expressions: The clear aperture radius d1 of the object side of the first lens, the true image height IH corresponding to the maximum field angle of the optical lens, and the maximum field angle FOV of the optical lens satisfy: 0.21 < d1 / (IH / 2) / tan(FOV / 2) < 0.24; the true image height IH corresponding to the maximum field angle of the optical lens, the effective focal length f of the optical lens, and the radian value θ of the maximum semi-field angle of the optical lens satisfy: 0.9 < (IH / 2) / (f×θ) < 0.

93.

5. The optical lens according to claim 1, characterized in that, The optical lens satisfies one or more of the following conditional expressions: The effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -1.8 < f1 / f < -1.3; the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: -26 < f3 / f < -11.

6. The optical lens according to claim 1, characterized in that, The optical lens satisfies one or more of the following conditional expressions: The effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 1.6 < f4 / f < 2.3; the curvature radius R7 of the object side of the fourth lens and the curvature radius R8 of the image side of the fourth lens satisfy: 0.05 < R7 / R8 < 28.

7. The optical lens according to claim 1, characterized in that, The optical lens satisfies one or more of the following conditional expressions: The effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -15 < f5 / f < -6; The effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: 1 < f6 / f < 1.3; The effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: -1.2 < f7 / f < -0.9; The effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: 2.1 < f8 / f < 3.

5.

8. The optical lens according to claim 1, characterized in that, The optical lens satisfies one or more of the following conditional expressions: The combined focal length f1234 of the first lens, the second lens, the third lens, and the fourth lens and the effective focal length f of the optical lens satisfy: 1.7 < f1234 / f < 2.3; The focal length f2 of the second lens and the combined focal length f1234 of the first lens, the second lens, the third lens, and the fourth lens satisfy: -13 < f2 / f1234 < -4.

2.

9. The optical lens according to claim 1, characterized in that, The optical lens satisfies one or more of the following conditional expressions: The focal length f2 of the second lens and the focal length f3 of the third lens satisfy: 0.45 < f2 / f3 < 1.2; The object-side curvature radius R3 of the second lens and the effective focal length f of the optical lens satisfy: -5.5 < R3 / f < -1.15; The image-side curvature radius R4 of the second lens and the effective focal length f of the optical lens satisfy: -16.5 < R4 / f < -1.7; The object-side curvature radius R5 of the third lens and the effective focal length f of the optical lens satisfy: -5 < R5 / f < -1.1; The image-side curvature radius R6 of the third lens and the effective focal length f of the optical lens satisfy: -8.5 < R6 / f < -1.

5.

10. The optical lens according to claim 1, characterized in that, The optical lens satisfies one or more of the following conditional expressions: The focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: -25.27 < f2 / f < -8.29; The object-side curvature radius R3 of the second lens and the image-side curvature radius R4 of the second lens satisfy: -0.52 < (R3 - R4) / (R3 + R4) < -0.17.

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