Optical lens

Abstract

The present invention provides an optical lens having eight lenses, which include, in order from the object side to the imaging surface along the optical axis: a first lens having negative optical power, whose object side surface is convex and whose image side surface is concave; a second lens having negative optical power, whose image side surface is concave; a third lens having positive optical power, whose object side surface and image side surface are both convex; a fourth lens having positive optical power, whose object side surface and image side surface are both convex; a fifth lens having positive optical power, whose object side surface and image side surface are both convex; a sixth lens having negative optical power, whose object side surface and image side surface are both concave; a seventh lens having negative optical power, whose object side surface is convex and whose image side surface is concave; and an eighth lens having positive optical power, whose object side surface is convex and whose image side surface is concave. The optical lens provided by the present invention improves the imaging quality of the optical lens, reduces aberrations, and improves the imaging quality of the optical lens through the reasonable configuration of the surface shapes of each lens and the reasonable matching of the optical powers.

Description

Technical Field

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

[0002] With the continuous advancement and development of existing image processing algorithms and AI technology, fisheye lenses, as a special type of optical lens, are widely used in various fields such as sports cameras, drones, smart doorbells and smart homes. Therefore, the requirements for fisheye lenses are becoming higher and higher.

[0003] However, existing fisheye lens equipment still has many shortcomings. For example, the lens is too long, large in size, and heavy in weight, which is not convenient for carrying; the increased field of view of the lens makes it difficult to correct system aberrations and reduces the imaging quality; the relative aperture of the lens is small, the light transmission performance is poor, and it cannot adapt to darker environments; and the existing lens imaging target area is small, which makes it difficult to meet market demand.

[0004] Therefore, it is necessary to develop an optical lens with one or more advantages such as a large field of view, high imaging quality, a large aperture, a small size, and a large target surface, so as to better meet the market's high demand for fisheye lenses. Summary of the Invention

[0005] In view of the above problems, an object of the present invention is to provide an optical lens having the advantage of excellent imaging quality.

[0006] The present invention provides an optical lens, comprising eight lenses, which include the following lenses in order from the object side to the imaging surface along the optical axis:

[0007] a first lens having negative optical power, wherein the object-side surface is convex and the image-side surface is concave;

[0008] a second lens element having negative optical power and a concave image-side surface;

[0009] The third lens has positive optical power and its object-side and image-side surfaces are both convex;

[0010] The fourth lens element has positive refractive power, and both the object-side surface and the image-side surface are convex;

[0011] The fifth lens has positive refractive power, and both the object-side surface and the image-side surface are convex;

[0012] a sixth lens element having negative optical power, wherein both the object-side surface and the image-side surface are concave;

[0013] a seventh lens element having negative optical power, whose object-side surface is convex and whose image-side surface is concave;

[0014] an eighth lens element having positive optical power, whose object-side surface is convex and whose image-side surface is concave;

[0015] The effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle satisfy: 3.2 <IH / f<4.0。

[0016] Further preferably, a reflective element is provided between the third lens and the fourth lens, and the surface of the reflective element facing the object side is the incident surface, and the surface facing the imaging surface is the exit surface.

[0017] Further preferably, the reflective element is a prism, and both the incident surface and the exit surface of the prism are planes.

[0018] Further preferably, a protective lens is provided between the first lens and the object side, wherein the object side surface of the protective lens is convex and the image side surface is concave.

[0019] Further preferably, the object side curvature radius R of the seventh lens is 13 and the image side curvature radius R 14 Satisfaction: (R 13 +R 14 ) / (R 13 -R 14) >2.5.

[0020] Further preferably, the distance CT between the third lens and the fourth lens on the optical axis is 34 The effective focal length f of the optical lens satisfies: 4.0 <CT 34 / f<5.5.

[0021] Further preferably, the maximum field of view FOV of the optical lens satisfies: FOV>190°.

[0022] Further preferably, the total optical length TTL and the effective focal length f of the optical lens meet the following conditions: 17.0 <TTL / f<20.0。

[0023] Further preferably, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: -4.5 <f1 / f<-3.5。

[0024] Further preferably, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: -4.5 <f2 / f<-3.0。

[0025] Further preferably, the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 4.0 <f3 / f<6.0。

[0026] The optical lens provided by the present invention improves the imaging quality of the optical lens, reduces aberrations, and improves the imaging quality of the optical lens through the reasonable configuration of the surface shapes of each lens and the reasonable matching of the optical focal length. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0028] Figure 1 and Figure 2 They are schematic structural diagrams of the optical lens without and with protective lenses in Example 1 of the present invention.

[0029] Figure 3 Graph showing the field curvature of the optical lens in Example 1 of the present invention.

[0030] Figure 4 : is the F-Theta distortion curve of the optical lens in Example 1 of the present invention.

[0031] Figure 5 This is a relative illumination curve diagram of the optical lens in Example 1 of the present invention.

[0032] Figure 6 This is the MTF curve of the optical lens in Example 1 of the present invention.

[0033] Figure 7 1 is an axial aberration curve diagram of the optical lens in Example 1 of the present invention.

[0034] Figure 8 Graph showing the vertical axis chromatic aberration of the optical lens in Example 1 of the present invention.

[0035] Figure 9 and Figure 10 They are schematic structural diagrams of the optical lens without and with protective lenses in Example 2 of the present invention.

[0036] Figure 11 Graph showing the field curvature of the optical lens in Example 2 of the present invention.

[0037] Figure 12 : is the F-Theta distortion curve of the optical lens in Example 2 of the present invention.

[0038] Figure 13 This is a relative illumination curve diagram of the optical lens in Example 2 of the present invention.

[0039] Figure 14 This is an MTF curve diagram of the optical lens in Example 2 of the present invention.

[0040] Figure 15 2 is an axial aberration curve diagram of the optical lens in Example 2 of the present invention.

[0041] Figure 16 Graph showing vertical axis chromatic aberration of the optical lens in Example 2 of the present invention.

[0042] Figure 17 and Figure 18 They are schematic structural diagrams of the optical lens without and with protective lenses in Example 3 of the present invention.

[0043] Figure 19 4 is a field curvature curve diagram of the optical lens in Example 3 of the present invention.

[0044] Figure 20 : This is the F-Theta distortion curve of the optical lens in Example 3 of the present invention.

[0045] Figure 21 This is a relative illumination curve diagram of the optical lens in Example 3 of the present invention.

[0046] Figure 22 This is the MTF curve of the optical lens in Example 3 of the present invention.

[0047] Figure 23 4 is an axial aberration curve diagram of the optical lens in Example 3 of the present invention.

[0048] Figure 24 Graph showing vertical axis chromatic aberration of the optical lens in Example 3 of the present invention.

[0049] Figure 25 and Figure 26 They are schematic structural diagrams of the optical lens without and with protective lenses in Example 4 of the present invention.

[0050] Figure 27 4 is a field curvature curve diagram of the optical lens in Example 4 of the present invention.

[0051] Figure 28 : is the F-Theta distortion curve of the optical lens in Example 4 of the present invention.

[0052] Figure 29 This is a relative illumination curve diagram of the optical lens in Example 4 of the present invention.

[0053] Figure 30 This is the MTF curve of the optical lens in Example 4 of the present invention.

[0054] Figure 31 4 is an axial aberration curve diagram of the optical lens in Example 4 of the present invention.

[0055] Figure 32 Graph showing vertical axis chromatic aberration of the optical lens in Example 4 of the present invention.

[0056] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0057] For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely descriptions of embodiments of the present application and are not intended to limit the scope of the present 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.

[0058] It should be noted that in this specification, the terms "first," "second," "third," etc., are used solely to distinguish one feature from another and do not limit the features. Thus, the first lens discussed below could also be referred to as the second lens or the third lens without departing from the teachings of the present invention.

[0059] In the drawings, the thickness, size, and shape of the lenses are slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical and aspherical surfaces shown in the drawings are provided by way of example. That is, the shapes of the spherical and aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0060] In this article, the paraxial region refers to the area near the optical axis. If a lens surface is convex and the location of the convex surface is undefined, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the location of the concave surface is undefined, 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.

[0061] It should also be understood that the terms "comprises," "including," "having," "includes," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application." And, the term "exemplary" is intended to refer to an example or illustration.

[0062] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0063] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0064] The optical lens of the embodiment of the present invention includes, along the optical axis from the object side to the imaging surface, a first lens, a second lens, a third lens, a fourth lens, an aperture, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a filter.

[0065] In some embodiments, the first lens element may have negative power to reduce the angle of incident light, effectively sharing the large object-side field of view. The first lens element has a convex object-side surface and a concave image-side surface, which helps collect as much light from the edge of the field of view as possible and feed it into the rear optical element, achieving wide-angle light collection.

[0066] In some embodiments, the second lens element may have negative optical power, which helps smooth the transition of light, expands the field of view of the optical imaging lens, reduces the difficulty of correcting distortion and chromatic aberration in the rear lens, and improves image quality. The image side surface of the second lens element is concave, which helps increase the field of view of the optical lens and improve the imaging quality of the optical lens.

[0067] In some embodiments, the third lens element may have positive optical power, which helps improve the light-gathering ability of the optical lens. Both the object-side and image-side surfaces of the third lens element are convex, which helps balance various aberrations produced by the optical lens and improve the imaging quality of the optical lens.

[0068] In some embodiments, the fourth lens may have positive optical power, and its object-side surface and image-side surface are both convex; this is beneficial for improving the light-converging ability of the optical lens, while balancing the aberrations of the optical lens and improving the imaging quality of the optical lens.

[0069] In some embodiments, the fifth lens may have positive optical power, and its object-side surface and image-side surface are both convex; this is beneficial for improving the light-converging ability of the optical lens, while balancing the aberrations of the optical lens and improving the imaging quality of the optical lens.

[0070] In some embodiments, the sixth lens element may have negative optical power, and both the object-side surface and the image-side surface thereof are concave; this is beneficial for increasing the field of view of the optical lens and improving the imaging quality of the optical lens.

[0071] In some embodiments, the seventh lens element may have negative optical power, with a convex object-side surface and a concave image-side surface; this is beneficial for increasing the field of view of the optical lens and improving the imaging quality of the optical lens.

[0072] In some embodiments, the eighth lens may have a positive optical power, with its object side surface being convex and its image side surface being concave; this is beneficial for suppressing the angle of the marginal field of view incident on the imaging surface, effectively transmitting more light beams to the imaging surface, and at the same time being able to balance the aberration of the optical lens and improve the imaging quality of the optical lens.

[0073] In some embodiments, in order to reduce the size of the optical lens, a reflecting element with zero optical power for light path folding may be provided between the third lens and the fourth lens, and the reflecting element is a prism. The surface of the prism facing the object side is the incident surface, and the surface facing the imaging surface is the exit surface, and both the incident surface and the exit surface are flat surfaces. A right-angle prism can be used for the prism. Light rays from the object side direction enter the prism through the incident surface, are reflected by the reflecting surface, and then exit through the exit surface. By setting the prism to bend the light path, the thickness of the lens can be effectively shortened.

[0074] In some embodiments, in order to protect the first lens in contact with the outside, a protective lens with optical power is provided between the first lens and the object side. The object side surface of the protective lens is convex and the image side surface is concave. By setting the protective lens, it plays a role in protecting the optical lens, can improve the anti-impact and scratch-resistant ability of the optical lens, and has almost no impact on the imaging quality of the optical lens.

[0075] In some embodiments, the effective focal length f of the optical lens and the true image height IH corresponding to the maximum field of view angle satisfy: 3.2 < IH / f < 4.0. Meeting the above range can achieve the characteristics of a large image surface and improve the imaging quality of the optical lens.

[0076] In some embodiments, the curvature radius R of the object side surface of the seventh lens 13 and the curvature radius R of the image side surface 14 satisfy: (R 13 +R 14 ) / (R 13 -R 14) ) > 2.5. Meeting the above range can increase the image height by controlling the trend of the marginal field of view light beams and reduce the off-axis aberration of the optical lens at the same time.

[0077] In some embodiments, the distance CT on the optical axis between the third lens and the fourth lens 34 and the effective focal length f of the optical lens satisfy: 4.0 < CT 34 / f < 5.5. Meeting the above range is beneficial for realizing the folding structure of the optical lens and reducing the thickness of the lens.

[0078] In some embodiments, the maximum field of view angle FOV of the optical lens satisfies: FOV > 190°. Meeting the above range can achieve that the optical lens has a large field of view angle.

[0079] In some embodiments, the total optical length TTL of the optical lens and the effective focal length f satisfy: 17.0 < TTL / f < 20.0. Meeting the above range ensures that there is sufficient space to adjust the lens structure and optimize the imaging effect.

[0080] In some embodiments, the effective focal length f of the optical lens, the radian θ of the maximum half field angle, and the true image height IH corresponding to the maximum field angle satisfy: 0.8 < (IH / 2) / (f×θ) < 1.1. Meeting the above range controls the distortion within a suitable range, which is beneficial to increasing the true image height.

[0081] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: -4.5 < f1 / f < -3.5. Meeting the above range can make the first lens have an appropriate negative optical power, avoid over-concentration of the negative optical power, and at the same time is beneficial to increasing the field angle, facilitating the collection of edge field light into the rear optical lens as much as possible, and achieving large-angle light collection.

[0082] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: -4.5 < f2 / f < -3.0. Meeting the above range can make the second lens have an appropriate negative optical power, increase the field angle, and improve the imaging quality of the optical lens.

[0083] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 4.0 < f3 / f < 6.0. Meeting the above range can make the third lens have an appropriate positive optical power, which is beneficial to improving the light converging ability of the optical lens, and at the same time can balance various aberrations generated by the optical lens and improve the imaging quality of the optical lens.

[0084] In some embodiments, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 3.0 < f4 / f < 4.0. Meeting the above range can make the fourth lens have an appropriate positive optical power, which is beneficial to improving the light converging ability of the optical lens, and at the same time can balance the aberrations of the optical lens and improve the imaging quality of the optical lens.

[0085] In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 2.0 < f5 / f < 3.5. Meeting the above range can make the fifth lens have an appropriate positive optical power, which is beneficial to improving the light converging ability of the optical lens, and at the same time can balance the aberrations of the optical lens and improve the imaging quality of the optical lens.

[0086] In some embodiments, the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: -2.5 < f6 / f < -1.5. Meeting the above range can make the sixth lens have an appropriate negative optical power, which is beneficial to increasing the field angle of the optical lens and improving the imaging quality of the optical lens.

[0087] In some embodiments, the effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: f7 / f < -5.0. Meeting the above range can make the seventh lens have a negative optical power, which is beneficial to increasing the field angle of the optical lens and improving the imaging quality of the optical lens.

[0088] In some embodiments, the effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: 4.0 < f8 / f < 8.5. Meeting the above range can make the eighth lens have an appropriate positive optical power, which is beneficial to suppressing the angle of the marginal field incident on the imaging surface, effectively transmitting more light beams to the imaging surface, and at the same time balancing the aberration of the optical lens and improving the imaging quality of the optical lens.

[0089] In some embodiments, the focal length f1 of the first lens of the optical lens and the focal length f2 of the second lens satisfy: 1.0 < f1 / f2 < 1.2. Meeting the above range can make the first lens and the second lens have an appropriate negative optical power, which helps the light to transition smoothly, expands the field angle of the optical lens, reduces the difficulty of correcting distortion and chromatic aberration of the rear lenses, and improves the imaging quality of the optical lens.

[0090] In some embodiments, the sixth lens and the seventh lens can be glued together to form a glued 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 technology difficulty of the optical lens and improving the assembly yield of the optical lens.

[0091] To make the system have better optical performance, multiple aspherical lenses are used in the lens, and the aspherical surface shapes of the optical lens satisfy the following equation:

[0092]

[0093] Where, z is the distance between the curved surface and the vertex of the curved surface in the optical axis direction, h is the distance from the optical axis to the curved surface, c is the curvature of the vertex of the curved surface, K is the conic coefficient, and A, B, C, D, E, F are the surface coefficients of the second order, fourth order, sixth order, eighth order, tenth order, and twelfth order respectively.

[0094] The protective lens adopts an aspherical surface type, and the aspherical surface shape satisfies the following equation:

[0095]

[0096] Where z is the distance between the surface and the vertex in the direction of the optical axis, h is the distance from the optical axis to the surface, c is the curvature of the surface vertex, K is the quadratic surface coefficient, and A, B, C, D, E, and F are the second-order, fourth-order, sixth-order, eighth-order, tenth-order, and twelfth-order surface coefficients, respectively.

[0097] The present invention is further illustrated below with reference to several embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens vary; for details, please refer to the parameter tables of each embodiment. The following embodiments are merely preferred embodiments of the present invention, but the present invention is not limited thereto. Any other changes, substitutions, combinations, or simplifications that do not deviate from the novelties of the present invention shall be considered equivalent replacements and are included within the scope of protection of the present invention.

[0098] Example 1

[0099] See also Figure 1 , shown is a schematic structural diagram of the optical lens provided in Example 1 of the present invention, which includes, along the optical axis from the object side to the imaging surface, a first lens L1, a second lens L2, a third lens L3, a prism G1, 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 G2.

[0100] The first lens L1 has negative refractive power, its object-side surface S1 is convex, and its image-side surface S2 is concave;

[0101] The second lens L2 has negative refractive power, and its object-side surface S3 and image-side surface S4 are both concave;

[0102] The third lens L3 has positive refractive power, and its object-side surface S5 and image-side surface S6 are both convex;

[0103] The surface of the prism G1 facing the object side is the incident surface, and the surface facing the imaging surface is the exit surface. Both the incident surface and the exit surface are planes.

[0104] The fourth lens L4 has positive refractive power, and its object-side surface S7 and image-side surface S8 are both convex;

[0105] Aperture ST;

[0106] The fifth lens L5 has positive refractive power, and its object-side surface S9 and image-side surface S10 are both convex;

[0107] The sixth lens L6 has negative refractive power, and its object-side surface S11 and image-side surface S12 are both concave;

[0108] The seventh lens L7 has negative refractive power, its object-side surface S12 is convex, and its image-side surface S13 is concave;

[0109] The sixth lens L6 and the seventh lens L7 form a cemented lens group. That is, the cemented surface between the image-side surface of the sixth lens L6 and the object-side surface of the seventh lens L7 is S12.

[0110] The eighth lens L8 has positive refractive power, its object-side surface S14 is convex, and its image-side surface S15 is concave;

[0111] The object-side surface S16 and the image-side surface S17 of the filter G2 are both flat surfaces;

[0112] The imaging surface S18 is a plane.

[0113] The relevant parameters of each lens in the optical lens in Example 1 are shown in Table 1-1.

[0114] Table 1-1

[0115]

[0116] The surface parameters of the aspheric lens of the optical lens in Example 1 are shown in Table 1-2.

[0117] Table 1-2

[0118]

[0119] See Figure 2 In this embodiment, to protect the optical lens, a removable protective lens can be added between the first lens L1 and the object side. This protective lens has positive optical power, a convex object-side surface S19, and a concave image-side surface S20. Related parameters are shown in Tables 1-3.

[0120] Table 1-3

[0121]

[0122] In this embodiment, the field curvature curve, F-Theta distortion curve, relative illumination curve, MTF curve, axial aberration curve, and vertical chromatic aberration curve of the optical lens are shown as follows: Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 shown.

[0123] Figure 3 The field curvature curves for Example 1 are shown, representing 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 angle (unit: degrees). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within a range of -0.05 to 0.02 mm, demonstrating that the optical lens is capable of effectively correcting field curvature.

[0124] Figure 4 The F-Theta distortion curve for Example 1 is shown. It represents the F-Theta distortion of light of different wavelengths at different image heights on the imaging surface. The horizontal axis represents the F-Theta 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 0-8%, and the image compression in the edge angle area is relatively smooth, which effectively improves the clarity of the expanded image.

[0125] Figure 5 The relative illumination curve for Example 1 is shown, representing the relative illumination values ​​at different field angles on the imaging plane. The horizontal axis represents the half field angle (unit: degrees), and the vertical axis represents the relative illumination (unit: %). As can be seen from the graph, the relative illumination value of the optical lens is still greater than 40% at the maximum half field angle, indicating that the optical lens has good relative illumination.

[0126] Figure 6 The MTF (Modulation Transfer Function) curve for Example 1 is shown. It represents the degree of lens imaging modulation at different spatial frequencies across the field of view. The horizontal axis represents spatial frequency (lp / mm), and the vertical axis represents the MTF value. As can be seen from the graph, the MTF value of this example is consistently above 0.3 across the entire field of view. Within the range of 0 to 160 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, demonstrating excellent imaging quality and detail resolution at both low and high frequencies.

[0127] Figure 7 The following graph shows the axial aberration curve for Example 1, which represents the aberration on the optical axis at the imaging plane for each wavelength. The horizontal axis represents the axial aberration value (unit: μm), and the vertical axis represents the normalized pupil radius. As can be seen from the graph, the offset of the axial aberration is controlled within a range of -20μm to 15μm, indicating that the optical lens can effectively correct axial aberration.

[0128] Figure 8 The vertical chromatic aberration curve for Example 1 is shown. It plots the chromatic aberration of each wavelength relative to the central wavelength (0.55 μm) at different image heights on the imaging plane. The horizontal axis represents the vertical chromatic aberration value of each wavelength relative to the central wavelength (unit: μm), and the vertical axis represents the normalized field of view angle. As can be seen from the graph, the vertical chromatic aberration for both the longest and shortest wavelengths is controlled within a range of -3 μm to 1 μm, demonstrating that this optical lens is capable of excellently correcting chromatic aberration in the peripheral field of view and the secondary spectrum across the entire image plane.

[0129] Example 2

[0130] See also Figure 9, shown is a schematic structural diagram of the optical lens provided in Example 2 of the present invention. Compared with Example 1, this embodiment is different mainly in optical parameters such as the curvature radius of each lens surface and the lens thickness.

[0131] The relevant parameters of each lens in the optical lens in Example 2 are shown in Table 2-1.

[0132] Table 2-1

[0133]

[0134] The surface parameters of the aspheric lens of the optical lens in Example 2 are shown in Table 2-2.

[0135] Table 2-2

[0136]

[0137] See Figure 10 In this embodiment, to protect the optical lens, a removable protective lens can be added between the first lens L1 and the object side. This protective lens has positive optical power, a convex object-side surface S19, and a concave image-side surface S20. Related parameters are shown in Table 2-3.

[0138] Table 2-3

[0139]

[0140] In this embodiment, the field curvature curve, F-Theta distortion curve, relative illumination curve, MTF curve, axial aberration curve, and vertical chromatic aberration curve of the optical lens are shown as follows: Figure 11 、 Figure 12 、 Figure 13 、 Figure 14 、 Figure 15 、 Figure 16 shown.

[0141] Figure 11 The field curvature curves for Example 2 are shown, representing 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 angle (unit: degrees). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within a range of -0.05 to 0.02 mm, demonstrating that the optical lens is capable of effectively correcting field curvature.

[0142] Figure 12The F-Theta distortion curve for Example 2 is shown. It represents the F-Theta distortion of light of different wavelengths at different image heights on the imaging surface. The horizontal axis represents the F-Theta 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 0-3%, and the image compression in the edge angle area is relatively smooth, which effectively improves the clarity of the expanded image.

[0143] Figure 13 The relative illumination curve for Example 2 is shown, representing the relative illumination values ​​at different field angles on the imaging plane. The horizontal axis represents the half field angle (unit: degrees), and the vertical axis represents the relative illumination (unit: %). As can be seen from the graph, the relative illumination value of the optical lens is still greater than 40% at the maximum half field angle, indicating that the optical lens has good relative illumination.

[0144] Figure 14 The MTF (Modulation Transfer Function) curve for Example 2 is shown. It represents the degree of lens imaging modulation at different spatial frequencies across the field of view. The horizontal axis represents spatial frequency (lp / mm), and the vertical axis represents the MTF value. As can be seen from the graph, the MTF value of this example is consistently above 0.4 across the entire field of view. Within the range of 0 to 160 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, demonstrating excellent imaging quality and detail resolution at both low and high frequencies.

[0145] Figure 15 The following graph shows the axial aberration curve for Example 2, which plots the aberration along the optical axis at the imaging plane for each wavelength. The horizontal axis represents the axial aberration value (unit: μm), and the vertical axis represents the normalized pupil radius. As can be seen from the graph, the offset of the axial aberration is controlled within a range of -20 μm to 10 μm, demonstrating that the optical lens is capable of effectively correcting axial aberration.

[0146] Figure 16 The vertical chromatic aberration curve for Example 2 is shown. It plots the chromatic aberration of each wavelength relative to the central wavelength (0.55 μm) at different image heights on the imaging plane. The horizontal axis represents the vertical chromatic aberration value of each wavelength relative to the central wavelength (unit: μm), and the vertical axis represents the normalized field of view angle. As can be seen from the graph, the vertical chromatic aberration for both the longest and shortest wavelengths is controlled within a range of -2 μm to 1 μm, demonstrating that this optical lens is capable of excellently correcting chromatic aberration in the peripheral field of view and the secondary spectrum across the entire image plane.

[0147] Example 3

[0148] See also Figure 17, shown is a schematic structural diagram of an optical lens provided in Example 3 of the present invention, which includes, along the optical axis from the object side to the imaging surface, a first lens L1, a second lens L2, a third lens L3, a prism G1, 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 G2.

[0149] The first lens L1 has negative refractive power, its object-side surface S1 is convex, and its image-side surface S2 is concave;

[0150] The second lens L2 has negative refractive power, its object-side surface S3 is convex, and its image-side surface S4 is concave;

[0151] The third lens L3 has positive refractive power, and its object-side surface S5 and image-side surface S6 are both convex;

[0152] The surface of the prism G1 facing the object side is the incident surface, and the surface facing the imaging surface is the exit surface. Both the incident surface and the exit surface are planes.

[0153] The fourth lens L4 has positive refractive power, and its object-side surface S7 and image-side surface S8 are both convex;

[0154] Aperture ST;

[0155] The fifth lens L5 has positive refractive power, and its object-side surface S9 and image-side surface S10 are both convex;

[0156] The sixth lens L6 has negative refractive power, and its object-side surface S11 and image-side surface S12 are both concave;

[0157] The seventh lens L7 has negative refractive power, its object-side surface S12 is convex, and its image-side surface S13 is concave;

[0158] The sixth lens L6 and the seventh lens L7 form a cemented lens group. That is, the cemented surface between the image-side surface of the sixth lens L6 and the object-side surface of the seventh lens L7 is S12.

[0159] The eighth lens L8 has positive refractive power, its object-side surface S14 is convex, and its image-side surface S15 is concave;

[0160] The object-side surface S16 and the image-side surface S17 of the filter G2 are both flat surfaces;

[0161] The imaging surface S18 is a plane.

[0162] The relevant parameters of each lens in the optical lens in Example 3 are shown in Table 3-1.

[0163] Table 3-1

[0164]

[0165] The surface parameters of the aspheric lens of the optical lens in Example 3 are shown in Table 3-2.

[0166] Table 3-2

[0167]

[0168] See Figure 18 In this embodiment, to protect the optical lens, a removable protective lens can be added between the first lens L1 and the object side. This protective lens has positive optical power, a convex object-side surface S19, and a concave image-side surface S20. Related parameters are shown in Table 3-3.

[0169] Table 3-3

[0170]

[0171] Among them, the surface parameters of the aspheric surface of the protective lens are shown in Table 3-4.

[0172] Table 3-4

[0173]

[0174] In this embodiment, the field curvature curve, F-Theta distortion curve, relative illumination curve, MTF curve, axial aberration curve, and vertical chromatic aberration curve of the optical lens are shown as follows: Figure 19 、 Figure 20 、 Figure 21 、 Figure 22 、 Figure 23 、 Figure 24 shown.

[0175] Figure 19 The field curvature curves for Example 3 are shown, showing 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 angle (unit: degrees). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within -0.01 to 0.02 mm, demonstrating that the optical lens is capable of effectively correcting field curvature.

[0176] Figure 20 The F-Theta distortion curve for Example 3 is shown, representing the F-Theta distortion of light of different wavelengths at different image heights on the imaging surface. The horizontal axis represents the F-Theta 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 a range of -15% to 0, and the image compression at the edge angles is relatively smooth, effectively improving the clarity of the expanded image.

[0177] Figure 21The relative illumination curve for Example 3 is shown, representing the relative illumination values ​​at different field angles on the imaging plane. The horizontal axis represents the half field angle (unit: degrees), and the vertical axis represents the relative illumination (unit: %). As can be seen from the graph, the relative illumination value of the optical lens is still greater than 60% at the maximum half field angle, indicating that the optical lens has good relative illumination.

[0178] Figure 22 The MTF (Modulation Transfer Function) curve for Example 3 is shown. It represents the degree of lens imaging modulation at different spatial frequencies across the field of view. The horizontal axis represents spatial frequency (lp / mm), and the vertical axis represents the MTF value. As can be seen from the graph, the MTF value of this example is consistently above 0.4 across the entire field of view. Within the range of 0 to 160 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, demonstrating excellent imaging quality and detail resolution at both low and high frequencies.

[0179] Figure 23 The following graph shows the axial aberration curve for Example 3, which plots the aberration along the optical axis at the imaging plane for each wavelength. The horizontal axis represents the axial aberration value (in μm), and the vertical axis represents the normalized pupil radius. As can be seen from the graph, the axial aberration offset is controlled within a range of -5 μm to 10 μm, demonstrating that the optical lens is capable of effectively correcting axial aberration.

[0180] Figure 24 The vertical chromatic aberration curve for Example 3 is shown. It plots the chromatic aberration of each wavelength relative to the central wavelength (0.55 μm) at different image heights on the imaging plane. The horizontal axis represents the vertical chromatic aberration value of each wavelength relative to the central wavelength (unit: μm), and the vertical axis represents the normalized field of view angle. As can be seen from the graph, the vertical chromatic aberration for both the longest and shortest wavelengths is controlled within a range of -1 μm to 1 μm, demonstrating that this optical lens is capable of excellently correcting chromatic aberration in the peripheral field of view and the secondary spectrum across the entire image plane.

[0181] Example 4

[0182] See also Figure 25 , shown is a schematic structural diagram of the optical lens provided in Example 4 of the present invention. Compared with Example 3, this embodiment is different mainly in optical parameters such as the curvature radius of each lens surface and the lens thickness.

[0183] The relevant parameters of each lens in the optical lens in Example 4 are shown in Table 4-1.

[0184] Table 4-1

[0185]

[0186] The surface parameters of the aspheric lens of the optical lens in Example 4 are shown in Table 4-2.

[0187] Table 4-2

[0188]

[0189] See Figure 26 In this embodiment, to protect the optical lens, a removable protective lens can be added between the first lens L1 and the object side. This protective lens has positive optical power, a convex object-side surface S19, and a concave image-side surface S20. Related parameters are shown in Table 4-3.

[0190] Table 4-3

[0191]

[0192] Among them, the surface parameters of the aspheric surface of the protective lens are shown in Table 4-4.

[0193] Table 4-4

[0194]

[0195] In this embodiment, the field curvature curve, F-Theta distortion curve, relative illumination curve, MTF curve, axial aberration curve, and vertical chromatic aberration curve of the optical lens are shown as follows: Figure 27 、 Figure 28 、 Figure 29 、 Figure 30 、 Figure 31 、 Figure 32 shown.

[0196] Figure 27 The field curvature curves for Example 4 are shown, showing 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 angle (unit: degrees). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within a range of -0.04 to 0.02 mm, demonstrating that the optical lens is capable of effectively correcting field curvature.

[0197] Figure 28 The F-Theta distortion curve for Example 4 is shown, representing the F-Theta distortion of light of different wavelengths at different image heights on the imaging surface. The horizontal axis represents the F-Theta 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 a range of -15% to 0, and the image compression at the edge angles is relatively smooth, effectively improving the clarity of the expanded image.

[0198] Figure 29The relative illumination curve for Example 4 is shown, representing the relative illumination values ​​at different field angles on the imaging plane. The horizontal axis represents the half field angle (unit: degrees), and the vertical axis represents the relative illumination (unit: %). As can be seen from the graph, the relative illumination value of the optical lens is still greater than 60% at the maximum half field angle, indicating that the optical lens has good relative illumination.

[0199] Figure 30 The MTF (Modulation Transfer Function) curve for Example 4 is shown. It represents the degree of lens imaging modulation at different spatial frequencies across the field of view. The horizontal axis represents spatial frequency (lp / mm), and the vertical axis represents the MTF value. As can be seen from the graph, the MTF value of this example is consistently above 0.4 across the entire field of view. Within the range of 0 to 160 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edges of the field of view, demonstrating excellent imaging quality and detail resolution at both low and high frequencies.

[0200] Figure 31 The following graph shows the axial aberration curve for Example 4, which plots the aberration along the optical axis at the imaging plane for each wavelength. The horizontal axis represents the axial aberration value (unit: μm), and the vertical axis represents the normalized pupil radius. As can be seen from the graph, the offset of the axial aberration is controlled within a range of -50 μm to 15 μm, demonstrating that the optical lens is capable of effectively correcting axial aberration.

[0201] Figure 32 The vertical chromatic aberration curve for Example 4 is shown. It plots the chromatic aberration of each wavelength relative to the central wavelength (0.55 μm) at different image heights on the imaging plane. The horizontal axis represents the vertical chromatic aberration value of each wavelength relative to the central wavelength (unit: μm), and the vertical axis represents the normalized field of view angle. As can be seen from the graph, the vertical chromatic aberration for both the longest and shortest wavelengths is controlled within a range of -1 μm to 1 μm, demonstrating that this optical lens is capable of excellently correcting chromatic aberration in the peripheral field of view and the secondary spectrum across the entire image plane.

[0202] Please refer to Table 5, which shows the optical characteristics corresponding to the above embodiments, including the effective focal length f, total optical length TTL, aperture value FNO, true image height IH and maximum field of view FOV of the optical lens, as well as the numerical values ​​corresponding to each conditional expression in each embodiment.

[0203] Table 5

[0204]

[0205] In summary of the above embodiments, the optical lens provided by the present invention improves the imaging quality of the optical lens, reduces aberrations, and improves the imaging quality of the optical lens through the reasonable configuration of the surface shapes of each lens and the reasonable matching of the optical power.

[0206] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations 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 any one or more embodiments or examples.

[0207] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An optical lens, comprising eight lenses, characterized in that: Along the optical axis from the object side to the imaging surface, it includes: a first lens having negative optical power, wherein the object-side surface is convex and the image-side surface is concave; a second lens element having negative optical power and a concave image-side surface; The third lens has positive optical power and its object-side and image-side surfaces are both convex; The fourth lens element has positive refractive power, and both the object-side surface and the image-side surface are convex; The fifth lens has positive refractive power, and both the object-side surface and the image-side surface are convex; a sixth lens element having negative optical power, wherein both the object-side surface and the image-side surface are concave; a seventh lens element having negative optical power, whose object-side surface is convex and whose image-side surface is concave; an eighth lens element having positive optical power, whose object-side surface is convex and whose image-side surface is concave; The effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle satisfy: 3.2 <IH / f<4.0。 2. The optical lens according to claim 1, wherein: A reflective element is provided between the third lens and the fourth lens. The surface of the reflective element facing the object side is the incident surface, and the surface facing the imaging surface is the exit surface.

3. The optical lens according to claim 1, wherein: A protective lens is provided between the first lens and the object side. The object side of the protective lens is convex, and the image side is concave.

4. The optical lens according to claim 1, wherein: The object side curvature radius R of the seventh lens 13 and the image side curvature radius R 14 Satisfaction: (R 13 +R 14 ) / (R 13 -R 14) >2.

5.

5. The optical lens according to claim 1, wherein: The distance CT between the third lens and the fourth lens on the optical axis 34 The effective focal length f of the optical lens satisfies: 4.0 <CT 34 / f<5.

5.

6. The optical lens according to claim 1, wherein: The maximum field of view (FOV) of the optical lens satisfies: FOV>190°.

7. The optical lens according to claim 1, wherein: The total optical length TTL of the optical lens and the effective focal length f meet 17.0 <TTL / f<20.0。 8. The optical lens according to claim 1, wherein: The focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: -4.5 <f1 / f<-3.5。 9. The optical lens according to claim 1, wherein: The focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: -4.5 <f2 / f<-3.0。 10. The optical lens according to claim 1, wherein: The focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 4.0 <f3 / f<6.0。

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