CN114675405A

CN114675405A - Optical lens

Info

Publication number: CN114675405A
Application number: CN202210584103.1A
Authority: CN
Inventors: 魏文哲; 王克民
Original assignee: Jiangxi Lianchuang Electronic Co Ltd
Current assignee: Hefei Lianchuang Optical Co ltd
Priority date: 2022-05-27
Filing date: 2022-05-27
Publication date: 2022-06-28
Anticipated expiration: 2042-05-27
Also published as: CN114675405B

Abstract

The invention provides an optical lens, which comprises eight lenses in total, and the eight lenses are sequentially arranged from an object side to an imaging surface along an optical axis as follows: the first lens with negative focal power has a convex object-side surface and a concave image-side surface; the second lens with negative focal power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; a third lens with negative focal power, wherein the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface; a fourth lens having an optical power; a diaphragm; a fifth lens having a positive refractive power, an object-side surface of which is convex; a sixth lens element having a negative refractive power, the object-side surface of which is concave; a seventh lens element with positive optical power, wherein both the object-side surface and the image-side surface of the seventh lens element are convex; an eighth lens having a positive refractive power, an object-side surface of which is convex; the effective focal length f of the optical lens and the focal length f1 of the first lens meet the following conditions: -9.5 < f1/f < -4.0. The optical lens realizes the effects of large field angle, large aperture, high definition and high imaging quality.

Description

Optical lens

Technical Field

The invention relates to the technical field of imaging lenses, in particular to an optical lens.

Background

With the rapid development of Advanced Driving Assistance Systems (ADAS), the vehicle-mounted lens has wider application and development. The method comprises a vehicle data recorder, automatic parking, front vehicle collision early warning (FCW), lane departure early warning (LDW), pedestrian detection early warning (PCW) and the like. Although the conventional wide-angle vehicular lens can basically meet the basic requirements of the use of the large-field vehicular lens, the defects such as too small field angle, too small aperture, low definition and low imaging quality still exist.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide an optical lens having advantages of a large field angle, a large aperture, high definition, and high imaging quality.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the invention provides an optical lens, which comprises eight lenses in total, and the eight lenses are sequentially arranged from an object side to an imaging surface along an optical axis as follows:

the first lens with negative focal power has a convex object-side surface and a concave image-side surface;

the second lens with negative focal power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;

a third lens with negative focal power, wherein the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface;

a fourth lens having an optical power;

a diaphragm;

a fifth lens having a positive refractive power, an object-side surface of which is convex;

a sixth lens element having a negative refractive power, the object-side surface of which is concave;

a seventh lens element with positive optical power, wherein both the object-side surface and the image-side surface of the seventh lens element are convex;

an eighth lens having a positive refractive power, an object-side surface of which is convex;

the effective focal length f of the optical lens and the focal length f1 of the first lens meet the following conditions: -9.5 < f1/f < -4.0.

Preferably, the total optical length TTL and the effective focal length f of the optical lens satisfy: TTL/f is more than 10 and less than 24.

Preferably, the effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle satisfy: IH/f is more than 1.6 and less than 3.0.

Preferably, the optical back focus BFL and the effective focal length f of the optical lens satisfy: BFL/f is more than 1.1 and less than 1.6.

Preferably, the incident angle CRA on the image plane of the full-field chief ray of the optical lens satisfies: 1 DEG < CRA < 13 deg.

Preferably, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -20 < f2/f < -6.5.

Preferably, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: -65 < f3/f < -7.5.

Preferably, the effective focal length f of the optical lens and the combined focal length f14 of the first lens to the fourth lens satisfy: -18 < f14/f < -2.0.

Preferably, the focal length f4 of the fourth lens and the object-side and image-side radii of curvature R7 and R8 of the fourth lens satisfy: i R7/f 4I < 1.1, and I R8/f 4I < 4.0.

Preferably, the seventh lens object-side radius of curvature R13 and the image-side radius of curvature R14 satisfy: -1.2 < R13/R14 < -0.7.

Compared with the prior art, the invention has the beneficial effects that: the optical lens of the application combines with the focal power through the lens shape and the focal power between each lens of reasonable collocation, has realized the effect of optical lens large field angle, big light ring, high definition and high imaging quality.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

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

fig. 1 is a schematic structural diagram of an optical lens system according to embodiment 1 of the present invention;

fig. 2 is a field curvature graph of the optical lens in embodiment 1 of the present invention;

FIG. 3 is a graph showing F-Theta distortion of an optical lens in example 1 of the present invention;

fig. 4 is a graph showing a relative illuminance curve of the optical lens in embodiment 1 of the present invention;

fig. 5 is a MTF graph of the optical lens in embodiment 1 of the present invention;

fig. 6 is a graph showing axial aberration of the optical lens in embodiment 1 of the present invention;

FIG. 7 is a vertical axis chromatic aberration diagram of an optical lens in embodiment 1 of the present invention;

fig. 8 is a schematic structural diagram of an optical lens system according to embodiment 2 of the present invention;

FIG. 9 is a graph of curvature of field of an optical lens in embodiment 2 of the present invention;

FIG. 10 is a graph showing F-Theta distortion of an optical lens in example 2 of the present invention;

fig. 11 is a graph showing a relative illumination of an optical lens in embodiment 2 of the present invention;

fig. 12 is a MTF graph of an optical lens in embodiment 2 of the present invention;

fig. 13 is a graph showing axial aberration of the optical lens in embodiment 2 of the present invention;

FIG. 14 is a vertical axis chromatic aberration diagram of an optical lens in embodiment 2 of the present invention;

fig. 15 is a schematic structural diagram of an optical lens system according to embodiment 3 of the present invention;

FIG. 16 is a graph of curvature of field of an optical lens in embodiment 3 of the present invention;

FIG. 17 is a graph showing F-Theta distortion of an optical lens in embodiment 3 of the present invention;

fig. 18 is a graph showing a relative illuminance curve of the optical lens in embodiment 3 of the present invention;

fig. 19 is a MTF graph of an optical lens in embodiment 3 of the present invention;

FIG. 20 is a graph showing axial aberrations of an optical lens according to embodiment 3 of the present invention;

FIG. 21 is a vertical axis chromatic aberration diagram of an optical lens in embodiment 3 of the present invention;

fig. 22 is a schematic structural diagram of an optical lens system according to embodiment 4 of the present invention;

FIG. 23 is a graph of curvature of field of an optical lens in embodiment 4 of the present invention;

FIG. 24 is a graph showing F-Theta distortion of an optical lens in example 4 of the present invention;

fig. 25 is a graph showing the relative illuminance of the optical lens in embodiment 4 of the present invention;

fig. 26 is a MTF graph of the optical lens in embodiment 4 of the present invention;

fig. 27 is a graph showing axial aberration of the optical lens in embodiment 4 of the present invention;

FIG. 28 is a vertical axis chromatic aberration diagram of an optical lens in embodiment 4 of the present invention;

fig. 29 is a schematic structural view of an optical lens system according to embodiment 5 of the present invention;

FIG. 30 is a graph showing curvature of field of an optical lens in embodiment 5 of the present invention;

FIG. 31 is a graph showing F-Theta distortion of an optical lens in example 5 of the present invention;

fig. 32 is a graph showing the relative illuminance of the optical lens in embodiment 5 of the present invention;

fig. 33 is a MTF graph of the optical lens in embodiment 5 of the present invention;

FIG. 34 is a graph showing axial aberrations of an optical lens in embodiment 5 of the present invention;

fig. 35 is a vertical axis chromatic aberration diagram of the optical lens in embodiment 5 of the present invention.

The following detailed description will further illustrate the invention in conjunction with the above-described figures.

Detailed Description

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 the detailed description is merely illustrative of embodiments of the application and does not limit the scope of the application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.

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

In the drawings, the thickness, size, and shape of the lens have been slightly exaggerated for convenience of explanation. In particular, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings. The figures are purely diagrammatic and not drawn to scale.

Herein, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position 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 concave position 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 object is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

It will be further understood that the terms "comprises," "comprising," "has," "having," "includes" and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Moreover, when a statement such as "at least one of" appears after a list of listed features, the entirety of the listed features is modified rather than modifying individual elements in the list. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.

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

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

An optical lens according to an embodiment of the present application includes, in order from an object side to an image side: the zoom lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens.

In some embodiments, the first lens may have a negative power, which is beneficial for reducing the inclination angle of the incident light, thereby achieving effective sharing of a large field of view of the object. The first lens can be of a convex-concave type, so that a larger field angle range is obtained, and large-field-of-view light rays can be collected to enter the rear lens as much as possible. In addition, in practical application, considering the outdoor installation and use environment of the vehicle-mounted application-type lens, the lens can be in severe weather such as rain, snow and the like, and the first lens is set to be in a meniscus shape with the convex surface facing the object side, so that water drops and the like can slide off favorably, and the influence on the imaging of the lens can be reduced.

In some embodiments, the second lens element may have a negative focal power, and the negative focal power of the front end of the optical lens element can be shared, so that the optical lens element is beneficial to avoiding the excessive light deflection caused by the over-concentration of the focal power of the first lens element, and the difficulty in correcting chromatic aberration of the optical lens element is reduced. The second lens can be of a convex-concave surface type, so that the working caliber of the second lens is reduced while the light collecting capacity of the marginal field of view is improved, and the miniaturization of the volume at the rear end of the optical lens is facilitated; in addition, the vertical axis chromatic aberration caused by overlarge deviation angle of marginal field-of-view rays in the process of transmitting the rays from the first lens to the second lens can be effectively avoided, and the difficulty in chromatic aberration correction of the optical lens is reduced.

In some embodiments, the third lens element may have a negative focal power, and also share the negative focal power of the front end of the optical lens, so as to avoid excessive light deflection caused by too concentrated focal power at the front end of the optical lens, and reduce difficulty in correcting chromatic aberration of the optical lens. The third lens can be of a concave-convex surface type, so that edge light rays can be gathered, the gathered light rays can smoothly enter the rear-end optical system, the trend of the light rays is further enabled to be approximately parallel to the optical axis, and subsequent correction on aberration, spherical aberration and other aberration is facilitated; meanwhile, the light ray incidence angle of the object side surface of the fourth lens can be effectively reduced, and the generation of larger aberration on the object side surface of the fourth lens is avoided.

In some embodiments, the fifth lens may have positive focal power, which is beneficial to improving the light converging capability of the peripheral field of view, so that the light trend is smoothly transited to the rear end of the optical lens, and meanwhile, the spherical aberration introduced by the front lens of the optical lens can be balanced. The fifth lens can be of a biconvex type or a convex-concave type, so that the energy of a ghost image projected on an image plane by the central area of the object side of the fifth lens due to reflection can be reduced, and the imaging quality of the optical lens is improved.

In some embodiments, the sixth lens element may have a negative focal power, which is beneficial to increasing the imaging area of the optical lens, and meanwhile, balancing various aberrations of the optical lens, thereby improving the imaging quality of the optical lens. The sixth lens can be of a biconcave type or a concave-convex type, so that the aberration which is difficult to correct when the incident light is converged by the object side surface can be reduced, and the correction pressure of the rear lens can be reduced.

In some embodiments, the seventh lens element may have a positive refractive power, which is beneficial to improving the light converging capability of the optical lens element, effectively transmitting more light beams to the rear lens element, and improving the imaging quality of the optical lens element. The seventh lens can be of a biconvex surface type, so that the light collection capability of the edge field of view is improved, the spherical aberration, the coma aberration and the astigmatism generated by the seventh lens are reduced, and the imaging quality of the optical lens is improved.

In some embodiments, the eighth lens element may have a positive refractive power, which is beneficial to suppress an angle of incidence of the peripheral field of view on the imaging plane, so as to effectively transmit more light beams to the imaging plane, thereby improving the imaging quality of the optical lens. The eighth lens can be of a biconvex type or a convex-concave type, so that the relative illumination of the edge field of view is favorably improved, the generation of a dark corner is avoided, and the imaging quality of the optical lens is improved.

In some embodiments, the fifth lens and the sixth lens or the sixth lens and the seventh lens can be cemented to form a cemented lens, which can effectively correct chromatic aberration of the optical lens, reduce eccentricity sensitivity of the optical lens, balance aberration of the optical lens, and improve imaging quality of the optical lens; the assembly sensitivity of the optical lens can be reduced, the processing difficulty of the optical lens is further reduced, and the assembly yield of the optical lens is improved.

In some embodiments, a diaphragm for limiting the light beam may be disposed between the fourth lens and the fifth lens, and the diaphragm may be disposed near an image side surface of the fourth lens or near an object side surface of the fifth lens, so as to reduce the generation of astigmatism in the optical lens, and facilitate the collection of light entering the optical system, and reduce the rear aperture of the optical lens.

In some embodiments, the object-side surface of the lens behind the diaphragm is a convex surface, which is beneficial to improving the illumination of the optical lens, so that the brightness of the optical lens at the image plane is improved to avoid the generation of a dark corner.

In some embodiments, the aperture value FNO of the optical lens satisfies: FNO is less than or equal to 1.80. The range is satisfied, the large aperture characteristic is favorably realized, and more incident rays are provided for the optical lens.

In some embodiments, the maximum field angle FOV of the optical lens satisfies: the FOV is less than or equal to 220 degrees. The method meets the range, is favorable for realizing the super wide angle characteristic, can acquire more scene information and meets the requirement of large-range detection of the optical lens.

In some embodiments, the incident angle CRA on the image plane of the full-field chief ray of the optical lens satisfies: 1 DEG < CRA < 13 deg. Satisfying the above range, the allowable error value between the CRA of the optical lens and the CRA of the chip photosensitive element can be made larger, and the adaptability of the optical lens to the image sensor can be improved.

In some embodiments, the maximum field angle FOV of the optical lens and the aperture value FNO satisfy: 120 ° < FOV/FNO. Satisfying the above range is advantageous for enlarging the field angle of the optical lens and increasing the aperture of the optical lens, and realizes the characteristics of an ultra-wide angle and a large aperture. The realization of the super-wide angle characteristic is favorable for the optical lens to acquire more scene information, the requirement of large-range detection is met, and the realization of the large aperture characteristic is favorable for improving the problem that the relative brightness of the marginal field of view is reduced rapidly caused by the super-wide angle, so that the acquisition of more scene information is also facilitated.

In some embodiments, the total optical length TTL and the effective focal length f of the optical lens satisfy: TTL/f is more than 10 and less than 24. The optical lens can effectively limit the length of the lens and is beneficial to realizing the miniaturization of the optical lens.

In some embodiments, the real image height IH at which the effective focal length f of the optical lens corresponds to the maximum field angle satisfies: IH/f is more than 1.6 and less than 3.0. Satisfying the above range can make the optical lens not only give consideration to the large image plane characteristics, but also have good imaging quality.

In some embodiments, the optical back focus BFL and the effective focal length f of the optical lens satisfy: BFL/f is more than 1.1 and less than 1.6. The method meets the range, is favorable for obtaining balance between good imaging quality and optical back focal length easy to assemble, and reduces the difficulty of the camera module assembly process while ensuring the imaging quality of the optical lens.

In some embodiments, the real image height IH of the optical lens corresponding to the maximum field angle and the entrance pupil diameter EPD satisfy: IH/EPD is more than 3.0 and less than 5.5. The width of the light ray bundle entering the optical lens can be increased, the brightness of the optical lens at the image plane is improved, the dark corner is avoided, and the field range and the image plane size of the optical lens can be enlarged.

In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -9.5 < f1/f < -4.0. The first lens has appropriate negative focal power, so that the field angle of the optical lens can be enlarged, the influence of distortion removal generated by the first lens on the integral distortion of the optical lens can be reduced, and the difficulty in correcting the distortion of the rear lens can be reduced.

In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -20 < f2/f < -6.5. The second lens has proper negative focal power and can share the negative focal power of the front end of the optical lens, so that the problem that light deflection is too large due to too concentrated focal power of the first lens is avoided, and the difficulty in correcting chromatic aberration of the optical lens is reduced.

In some embodiments, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: -65 < f3/f < -7.5. The third lens has appropriate negative focal power, so that stable light transition is facilitated, and the imaging quality of the optical lens is improved.

In some embodiments, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: i f4/f < 500. The optical lens meets the range, the fourth lens has proper focal power, light can be smoothly transited, and the imaging quality of the optical lens is improved.

In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: f5/f is more than 2.0 and less than 3.8. The fifth lens has proper positive focal power, so that the spherical aberration, the coma aberration, the astigmatism and the field curvature of the optical lens can be balanced, and the imaging quality of the optical lens is improved.

In some embodiments, the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: -2.8 < f6/f < -1.7. The sixth lens element has a proper negative focal power, so that astigmatism and curvature of field of the optical lens are balanced, and the imaging quality of the optical lens is improved.

In some embodiments, the effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: 2.4 < f7/f < 3.5. The seventh lens has appropriate positive focal power, so that the field curvature of the optical lens can be balanced, and the imaging quality of the optical lens can be improved.

In some embodiments, the effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: f8/f is more than 4.0 and less than 8.0. Satisfying the above range, the eighth lens element can have a proper positive focal power, which is beneficial to balance astigmatism of the optical lens and improve the imaging quality of the optical lens.

In some embodiments, the effective focal length f of the optical lens and the combined focal length f14 of the first lens to the fourth lens satisfy: -18.0 < f14/f < -2.0. The method meets the range, is favorable for converging light rays in a large-angle range to realize an ultra-wide-angle characteristic, simultaneously improves the resolution of an edge view field, and balances the total length of the optical lens and good imaging quality in a short time.

In some embodiments, the effective focal length f of the optical lens and the first lens object side radius of curvature R1 and the first lens image side radius of curvature R2 satisfy: r1/f is more than 8.0 and less than 13, and R2/f is more than 2.0 and less than 4.4. The method meets the range, is favorable for realizing the super wide angle characteristic, can acquire more scene information and meets the requirement of large-range detection of the optical lens.

In some embodiments, the second lens object side radius of curvature R3 and the second lens image side radius of curvature R4 satisfy: 3.0 < (R3+ R4)/(R3-R4) < 7.8. The optical lens meets the range, is favorable for balancing the off-axis point aberration generated by the second lens, and improves the imaging quality of the optical lens.

In some embodiments, the second lens image side radius of curvature R4 and the third lens object side radius of curvature R5 satisfy: -0.8 < R4/R5 < -0.6. The shape of the image side surface of the second lens and the shape of the object side surface of the third lens can be controlled to be closer to a concentric circle structure, so that aberration generated when light enters the object side surface of the third lens can be effectively reduced, and the imaging quality of the optical lens is improved.

In some embodiments, the third lens object-side radius of curvature R5 and the image-side radius of curvature R6 satisfy: -8.8 < (R5+ R6)/(R5-R6) < -2.5. The shapes of the object side surface and the image side surface of the third lens can be controlled to be closer to the structure of the meniscus lens, so that various aberrations of the optical lens can be balanced, and the imaging quality of the optical lens can be improved.

In some embodiments, the focal length f4 of the fourth lens and the fourth lens object side radius of curvature R7 and the fourth lens image side radius of curvature R8 satisfy: i R7/f 4I < 1.1, and I R8/f 4I < 4.0. Satisfy above-mentioned scope, be favorable to avoiding the curvature radius of fourth lens object side and image side too big, the aberration that produces when can effectively avoiding light incident and during the emergence promotes optical lens's image quality.

In some embodiments, the effective focal length f of the optical lens and the object-side and image-side radii of curvature R9 and R10 of the fifth lens respectively satisfy: 2.0 < R9/f < 3.0, | R10/f | < 30. The optical lens meets the range, the on-axis point aberration generated by the fifth lens is balanced, and the imaging quality of the optical lens is improved.

In some embodiments, the seventh lens object side radius of curvature R13 and the image side radius of curvature R14 satisfy: -1.2 < R13/R14 < -0.7. The shape of the object side surface and the shape of the image side surface of the seventh lens can be controlled to be closer to a symmetrical concentric circle structure, so that the light trend is facilitated to be stably transited, various aberrations of the optical lens can be effectively balanced, and the imaging quality of the optical lens is improved.

In some embodiments, the seventh lens image side radius of curvature R14 and the eighth lens object side radius of curvature R15 satisfy: r14 is more than-1.1 and R15 is less than or equal to-0.8. The shape of the image side surface of the seventh lens and the shape of the object side surface of the eighth lens can be controlled to be closer to a symmetrical structure, so that the field curvature of the optical lens can be effectively balanced, and the imaging quality of the optical lens is improved.

In some embodiments, the eighth lens object side radius of curvature R15 and the image side radius of curvature R16 satisfy: -2.0 < (R15-R16)/(R15+ R16) < -0.5. Satisfying the above range is beneficial to balance the astigmatism of the optical lens and improve the imaging quality of the optical lens.

In some embodiments, the real image height IH corresponding to the maximum field angle of the optical lens and the maximum half field angle θ satisfy: 0.8mm/rad < (IH/2)/θ < 2.5 mm/rad. The optical lens can be balanced between the ultra-wide angle and the large image plane, so that the imaging quality of the optical lens is improved.

In some embodiments, the total optical length TTL of the optical lens and the distance T38 on the optical axis from the object-side surface of the second lens element to the image-side surface of the fourth lens element satisfy: T38/TTL is more than or equal to 0.35 and less than or equal to 0.5. Satisfying the above range is advantageous for increasing the distance between the object-side surface of the second lens and the image-side surface of the fourth lens, so as to reduce the energy of the ghost image projected on the image plane due to reflection in the central regions of the second lens to the fourth lens.

In order to make the system have better optical performance, a plurality of aspheric lenses are adopted in the lens, and the surface shapes of the aspheric surfaces of the optical lens satisfy the following equation:

；

wherein z is the distance between the curved surface and the vertex of the curved surface in the optical axis direction, h is the distance between the optical axis and the curved surface, c is the curvature of the vertex of the curved surface, K is a quadric coefficient, and A, B, C, D, E, F are second-order, fourth-order, sixth-order, eighth-order, tenth-order and twelfth-order curved coefficients, respectively.

The invention is further illustrated below in the following examples. In various embodiments, the thickness, the curvature radius, and the material selection of each lens in the optical lens are different, and the specific differences can be referred to in the parameter tables of the various embodiments. The following examples are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited only by the following examples, and any other changes, substitutions, combinations or simplifications which do not depart from the innovative points of the present invention should be construed as being equivalent substitutions and shall be included within the scope of the present invention.

Example 1

Referring to fig. 1, a schematic structural diagram of an optical lens system according to embodiment 1 of the present invention is shown, the optical lens system sequentially includes, from an object side to an image plane along an optical axis: the lens system includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture stop ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a filter G1, and a protective glass G2.

The first lens element L1 has negative power, and has a convex object-side surface S1 and a concave image-side surface S2;

the second lens element L2 has negative power, and has a convex object-side surface S3 and a concave image-side surface S4;

the third lens element L3 has negative power, and has a concave object-side surface S5 and a convex image-side surface S6;

the fourth lens element L4 has positive power, and has a concave object-side surface S7 and a convex image-side surface S8;

a diaphragm ST;

the fifth lens element L5 has positive power, and has a convex object-side surface S9 and a concave image-side surface S10;

the sixth lens L6 has negative power, and both the object-side surface S11 and the image-side surface S12 are concave;

the seventh lens L7 has positive power, and both the object-side surface S13 and the image-side surface S14 are convex;

the eighth lens L8 has positive power, and both the object-side surface S15 and the image-side surface S16 are convex;

the sixth lens L6 and the seventh lens L7 may be cemented to form a cemented lens;

the object side surface S17 and the image side surface S18 of the filter G1 are both flat surfaces;

the object side surface S19 and the image side surface S20 of the protective glass G2 are both flat surfaces;

the image forming surface S21 is a plane.

The relevant parameters of each lens in the optical lens in example 1 are shown in table 1-1.

TABLE 1-1

The surface shape parameters of the aspherical lens of the optical lens in example 1 are shown in table 1-2.

Tables 1 to 2

In the present embodiment, a curvature of field curve graph, an F-Theta distortion graph, a relative illumination graph, an MTF graph, an axial aberration graph, and a vertical axis chromatic aberration graph of the optical lens are respectively shown in fig. 2, fig. 3, fig. 4, fig. 5, fig. 6, and fig. 7.

Fig. 2 shows a field curvature curve of example 1, which shows the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis representing the amount of displacement (unit: mm) and the vertical axis representing the half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.06 mm, which indicates that the field curvature of the optical lens is better corrected.

Fig. 3 shows an F-Theta distortion curve of example 1, which represents the F-Theta distortion of light rays of different wavelengths at different image heights on an image forming plane, the horizontal axis represents the F-Theta distortion (unit:%) and the vertical axis represents the half field angle (unit:%). As can be seen from the figure, the F-Theta distortion of the optical lens is controlled within-30% -0, which shows that the F-Theta distortion of the optical lens is effectively controlled, and the restoration is favorably carried out by a software algorithm in the later period.

Fig. 4 shows a relative illuminance curve of example 1, which represents relative illuminance values at different angles of field of view on the imaging plane, with the horizontal axis representing the half field angle (unit: °) and the vertical axis representing the relative illuminance (unit:%). As can be seen from the figure, the relative illuminance value of the optical lens is still greater than 60% at the maximum half field angle, which indicates that the relative illuminance of the optical lens is high.

Fig. 5 shows MTF (modulation transfer function) graphs of embodiment 1, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is more than 0.5 in the whole field of view, and in the range of 0-90 lp/mm, the MTF curve is uniformly and smoothly reduced in the process of the field of view from the center to the edge, and the MTF has good imaging quality and good detail resolution capability under the conditions of low frequency and high frequency.

Fig. 6 shows an axial aberration curve of example 1, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: mm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the offset of the axial aberration is controlled within ± 0.04mm, which indicates that the optical lens can effectively correct the axial aberration.

Fig. 7 shows a vertical axis chromatic aberration curve of example 1, which shows chromatic aberration at different image heights on an image forming plane for each wavelength with respect to a center wavelength (0.55 μm), the horizontal axis shows a vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis shows a normalized angle of view. As can be seen from the figure, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within +/-8 mu m, which shows that the optical lens can effectively correct the chromatic aberration of the marginal field of view and the secondary spectrum of the whole image plane.

Example 2

Referring to fig. 8, a schematic structural diagram of an optical lens system according to embodiment 2 of the present invention is shown, the optical lens system sequentially includes, from an object side to an image plane along an optical axis: the lens system includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture stop ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a filter G1, and a protective glass G2.

the fourth lens element L4 has negative power, and has a concave object-side surface S7 and a convex image-side surface S8;

a diaphragm ST;

the fifth lens L5 has positive power, and both the object-side surface S9 and the image-side surface S10 are convex;

the sixth lens L6 and the seventh lens L7 may be cemented to constitute a cemented lens.

The relevant parameters of each lens in the optical lens in embodiment 2 are shown in table 2-1.

TABLE 2-1

The surface shape parameters of the aspherical lens of the optical lens in example 2 are shown in table 2-2.

Tables 2 to 2

In the present embodiment, a field curvature graph, an F-Theta distortion graph, a relative illuminance graph, an MTF graph, an axial aberration graph, and a vertical axis chromatic aberration graph of the optical lens are respectively shown in fig. 9, fig. 10, fig. 11, fig. 12, fig. 13, and fig. 14.

Fig. 9 shows a field curvature curve of example 2, which shows the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis representing the amount of displacement (unit: mm) and the vertical axis representing the half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.06 mm, which indicates that the field curvature of the optical lens is better corrected.

FIG. 10 is a graph showing F-Theta distortion curves of example 2, in which F-Theta distortion is shown at different image heights on an image forming plane for light rays of different wavelengths, the abscissa indicates F-Theta distortion (unit:%), and the ordinate indicates half field angle (unit:%). As can be seen from the figure, the F-Theta distortion of the optical lens is controlled within-35% -0, which shows that the F-Theta distortion of the optical lens is effectively controlled.

Fig. 11 shows a relative illuminance curve of example 2, which represents relative illuminance values at different angles of field of view on an imaging plane, with the horizontal axis representing a half field angle (unit: °) and the vertical axis representing the relative illuminance (unit:%). As can be seen from the figure, the relative illuminance value of the optical lens is still greater than 60% at the maximum half field angle, which indicates that the relative illuminance of the optical lens is high.

Fig. 12 shows MTF (modulation transfer function) graphs of embodiment 2, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.4 in the whole field of view, and in the range of 0-90 lp/mm, the MTF curve is uniformly and smoothly reduced in the process from the center to the edge field of view, and the MTF has good imaging quality and good detail resolution capability under the conditions of low frequency and high frequency.

Fig. 13 shows an axial aberration curve of example 2, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: mm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the offset of the axial aberration is controlled within ± 0.03mm, which indicates that the optical lens can effectively correct the axial aberration.

Fig. 14 shows a vertical axis chromatic aberration curve of example 2, which shows chromatic aberration at different image heights on an image forming plane for each wavelength with respect to a center wavelength (0.55 μm), the horizontal axis shows a vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis shows a normalized angle of view. As can be seen from the figure, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within +/-8 mu m, which shows that the optical lens can effectively correct the chromatic aberration of the marginal field of view and the secondary spectrum of the whole image plane.

Example 3

Referring to fig. 15, a schematic structural diagram of an optical lens system according to embodiment 3 of the present invention is shown, the optical lens system sequentially includes, from an object side to an image plane along an optical axis: the lens system includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture stop ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a filter G1, and a protective glass G2.

the fourth lens L4 has positive power, and both the object-side surface S7 and the image-side surface S8 are convex;

a diaphragm ST;

the eighth lens element L8 has positive power, and has a convex object-side surface S15 and a concave image-side surface S16;

The relevant parameters of each lens in the optical lens in example 3 are shown in table 3-1.

TABLE 3-1

The surface shape parameters of the aspherical lens of the optical lens in example 3 are shown in table 3-2.

TABLE 3-2

In the present embodiment, a field curvature graph, an F-Theta distortion graph, a relative illuminance graph, an MTF graph, an axial aberration graph, and a vertical axis chromatic aberration graph of the optical lens are shown in fig. 16, 17, 18, 19, 20, and 21, respectively.

Fig. 16 shows a field curvature curve of example 3, which shows the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis representing the amount of displacement (unit: mm) and the vertical axis representing the half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.06 mm, which indicates that the field curvature of the optical lens is better corrected.

FIG. 17 is a graph showing F-Theta distortion curves of example 3, in which F-Theta distortion is shown at different image heights on an image forming plane for light rays of different wavelengths, the abscissa shows F-Theta distortion (unit:%), and the ordinate shows half field angle (unit:%). As can be seen from the figure, the F-Theta distortion of the optical lens is controlled within-35% -0, which shows that the F-Theta distortion of the optical lens is effectively controlled.

Fig. 18 shows a relative illuminance curve of example 3, which represents relative illuminance values at different angles of field of view on the imaging plane, with the horizontal axis representing the half field angle (unit: °), and the vertical axis representing the relative illuminance (unit:%). It can be seen from the figure that the relative illuminance value of the optical lens is still greater than 60% at the maximum half field angle, which indicates that the relative illuminance of the optical lens is higher.

Fig. 19 shows MTF (modulation transfer function) graphs of embodiment 3, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.5 in the whole field of view, and in the range of 0-90 lp/mm, the MTF curve is uniformly and smoothly reduced in the process from the center to the edge field of view, and the MTF has good imaging quality and good detail resolution capability under the conditions of low frequency and high frequency.

Fig. 20 shows an axial aberration curve of example 3, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: mm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the offset of the axial aberration is controlled within ± 0.032mm, which indicates that the optical lens can effectively correct the axial aberration.

Fig. 21 shows a vertical axis chromatic aberration curve of example 3, which shows chromatic aberration at different image heights on an image forming plane for each wavelength with respect to a center wavelength (0.55 μm), the horizontal axis shows a vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis shows a normalized angle of view. As can be seen from the figure, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within +/-7 mu m, which shows that the optical lens can effectively correct the chromatic aberration of the marginal field of view and the secondary spectrum of the whole image plane.

Example 4

Referring to fig. 22, a schematic structural diagram of an optical lens system according to embodiment 4 of the present invention is shown, the optical lens system sequentially includes, from an object side to an image plane along an optical axis: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a diaphragm ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a filter G1, and a protective glass G2.

the fourth lens element L4 has positive power, and has a convex object-side surface S7 and a concave image-side surface S8;

a diaphragm ST;

The relevant parameters of each lens in the optical lens in example 4 are shown in table 4-1.

TABLE 4-1

The surface shape parameters of the aspherical lens of the optical lens in example 4 are shown in table 4-2.

TABLE 4-2

In the present embodiment, a field curvature graph, an F-Theta distortion graph, a relative illuminance graph, an MTF graph, an axial aberration graph, and a vertical axis chromatic aberration graph of the optical lens are shown in fig. 23, 24, 25, 26, 27, and 28, respectively.

Fig. 23 shows a field curvature curve of example 4, which shows the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis representing the amount of displacement (unit: mm) and the vertical axis representing the half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.07 mm, which shows that the field curvature of the optical lens is better corrected.

Fig. 24 shows an F-Theta distortion curve of example 4, which represents the F-Theta distortion of light rays of different wavelengths at different image heights on an image forming plane, the horizontal axis represents the F-Theta distortion (unit:%) and the vertical axis represents the half field angle (unit:%). As can be seen from the figure, the F-Theta distortion of the optical lens is controlled within-35% -0, which shows that the F-Theta distortion of the optical lens is effectively controlled.

Fig. 25 shows a relative illuminance curve of example 4, which represents relative illuminance values at different angles of field of view on the imaging plane, with the horizontal axis representing the half field angle (unit: °) and the vertical axis representing the relative illuminance (unit:%). As can be seen from the figure, the relative illuminance value of the optical lens is still greater than 60% at the maximum half field angle, which indicates that the relative illuminance of the optical lens is high.

Fig. 26 shows MTF (modulation transfer function) graphs of embodiment 4, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.45 in the whole field of view, and in the range of 0-90 lp/mm, the MTF curve is uniformly and smoothly reduced in the process from the center to the edge field of view, and the MTF has good imaging quality and good detail resolution capability under the conditions of low frequency and high frequency.

Fig. 27 shows an axial aberration curve of example 4, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: mm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the offset of the axial aberration is controlled within ± 0.032mm, which indicates that the optical lens can effectively correct the axial aberration.

Fig. 28 shows a vertical axis chromatic aberration curve of example 4, which shows chromatic aberration at different image heights on an image forming plane for each wavelength with respect to a center wavelength (0.55 μm), the horizontal axis shows a vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis shows a normalized angle of view. As can be seen from the figure, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within +/-6 mu m, which shows that the optical lens can effectively correct the chromatic aberration of the marginal field of view and the secondary spectrum of the whole image plane.

Example 5

Referring to fig. 29, a schematic structural view of an optical lens system according to embodiment 5 of the present invention is shown, the optical lens system sequentially includes, from an object side to an image plane along an optical axis: the lens system includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture stop ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a filter G1, and a protective glass G2.

a diaphragm ST;

the sixth lens element L6 has negative power, and has a concave object-side surface S11 and a convex image-side surface S12;

the fifth lens L5 and the sixth lens L6 may be cemented to constitute a cemented lens.

The relevant parameters of each lens in the optical lens in example 5 are shown in table 5-1.

TABLE 5-1

The parameters of the surface shape of the aspherical lens of the optical lens in example 5 are shown in table 5-2.

TABLE 5-2

In the present embodiment, a field curvature graph, an F-Theta distortion graph, a relative illuminance graph, an MTF graph, an axial aberration graph, and a vertical axis chromatic aberration graph of the optical lens are shown in fig. 30, 31, 32, 33, 34, and 35, respectively.

Fig. 30 shows a field curvature curve of example 5, which shows the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis representing the amount of displacement (unit: mm) and the vertical axis representing the half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.07 mm, which shows that the field curvature of the optical lens is better corrected.

Fig. 31 shows an F-Theta distortion curve of example 5, which shows the F-Theta distortion at different image heights on the image forming plane for light rays of different wavelengths, with the horizontal axis showing the F-Theta distortion (unit:%) and the vertical axis showing the half field angle (unit:%). As can be seen from the figure, the F-Theta distortion of the optical lens is controlled within-55 to 0 percent, which shows that the F-Theta distortion of the optical lens is effectively controlled.

Fig. 32 shows a relative illuminance curve of example 5, which represents relative illuminance values at different angles of field of view on the imaging plane, with the horizontal axis representing the half field angle (unit: °) and the vertical axis representing the relative illuminance (unit:%). It can be seen from the figure that the relative illuminance value of the optical lens is still greater than 90% at the maximum half field angle, which indicates that the relative illuminance of the optical lens is higher.

Fig. 33 shows MTF (modulation transfer function) graphs of example 5, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.4 in the whole field of view, and in the range of 0-90 lp/mm, the MTF curve is uniformly and smoothly reduced in the process from the center to the edge field of view, and the MTF has good imaging quality and good detail resolution capability under the conditions of low frequency and high frequency.

Fig. 34 shows an axial aberration curve of example 5, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: mm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the offset of the axial aberration is controlled within ± 0.05mm, which indicates that the optical lens can effectively correct the axial aberration.

Fig. 35 shows a vertical axis chromatic aberration curve of example 5, which shows chromatic aberration at different image heights on an image forming plane for each wavelength with respect to a center wavelength (0.55 μm), the horizontal axis shows a vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis shows a normalized angle of view. As can be seen from the figure, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within +/-14 μm, which shows that the optical lens can effectively correct the chromatic aberration of the fringe field and the secondary spectrum of the whole image plane.

Please refer to table 6, which shows the optical characteristics corresponding to the above embodiments, including the effective focal length f, the total optical length TTL, the aperture FNO, the real image height IH, and the maximum field angle FOV of the optical lens, and the values corresponding to each conditional expression in the embodiments.

TABLE 6

In summary, the optical lens according to the embodiment of the invention realizes the effects of large field angle, large aperture, high definition and high imaging quality by reasonably matching the combination of the lens shapes and the focal powers between the lenses.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above examples are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. An optical lens system comprising eight lenses, in order from an object side to an image plane along an optical axis:

a fourth lens having an optical power;

a diaphragm;

a fifth lens having positive refractive power, the object-side surface of which is convex;

2. An optical lens according to claim 1, wherein the total optical length TTL and the effective focal length f satisfy: TTL/f is more than 10 and less than 24.

3. The optical lens according to claim 1, wherein a real image height IH of the optical lens corresponding to an effective focal length f and a maximum field angle satisfies: IH/f is more than 1.6 and less than 3.0.

4. An optical lens according to claim 1, characterized in that the optical back focus BFL and the effective focal length f of the optical lens satisfy: BFL/f is more than 1.1 and less than 1.6.

5. An optical lens according to claim 1, wherein the incidence angle CRA on the image plane of the full-field chief ray of the optical lens satisfies: 1 DEG < CRA < 13 deg.

6. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -20 < f2/f < -6.5.

7. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: -65 < f3/f < -7.5.

8. An optical lens according to claim 1, wherein an effective focal length f of the optical lens and a combined focal length f14 of the first to fourth lenses satisfy: -18 < f14/f < -2.0.

9. An optical lens according to claim 1, characterized in that the focal length f4 of the fourth lens and the fourth lens object side radius of curvature R7 and image side radius of curvature R8 satisfy: i R7/f 4I < 1.1, and I R8/f 4I < 4.0.

10. An optical lens as claimed in claim 1, characterized in that the seventh lens object side radius of curvature R13 and image side radius of curvature R14 satisfy: -1.2 < R13/R14 < -0.7.