CN114675402B

CN114675402B - Optical lens

Info

Publication number: CN114675402B
Application number: CN202210584122.4A
Authority: CN
Inventors: 魏文哲; 王克民
Original assignee: Jiangxi Lianchuang Electronic Co Ltd
Current assignee: Jiangxi Lianchuang Electronic Co Ltd
Priority date: 2022-05-27
Filing date: 2022-05-27
Publication date: 2022-10-25
Anticipated expiration: 2042-05-27
Also published as: CN114675402A

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 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 having optical power; a seventh lens having optical power; an eighth lens element having a positive refractive power, both the object-side surface and the image-side surface of the eighth lens element being convex; the effective focal length f of the optical lens and the focal length f2 of the second lens meet the following conditions: -25 < f2/f < -8.0. 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 a large-field vehicular lens, the conventional wide-angle vehicular lens still has the defects of too small field angle, too small aperture, low definition, low imaging quality and the like.

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:

an optical lens system comprises eight lenses, in order from an object side to an image plane along an optical axis:

a first lens element having a negative refractive power, the object-side surface of which is convex and the image-side surface of which is concave;

a second lens element having a negative refractive power, the object-side surface of the second lens element being convex and the image-side surface of the second lens element being concave;

a third lens with 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 having optical power;

a seventh lens having optical power;

an eighth lens element having a positive refractive power, both the object-side surface and the image-side surface of the eighth lens element being convex;

the effective focal length f of the optical lens and the focal length f2 of the second lens meet the following conditions: -25 < f2/f < -8.0.

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 14.

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 2.0 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 0.8 and less than 1.5.

Preferably, the incident angle CRA on the image plane of the full-field chief ray of the optical lens satisfies: 2 DEG < CRA < 20 deg.

Preferably, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: f1/f is more than-5.5 and less than or equal to-3.0.

Preferably, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: f1/f2 is more than 0.2 and less than 0.4.

Preferably, the effective focal length f of the optical lens and the combined focal length f13 of the first lens to the third lens satisfy: -5.2 < f13/f < -1.5.

Preferably, the effective focal length f of the optical lens and the combined focal length f67 of the sixth lens and the seventh lens satisfy: -42 < f67/f < -2.5.

Preferably, the first lens object side radius of curvature R1 and the second lens object side radius of curvature R3 satisfy: R1/R3 is more than 2.2 and less than 4.0.

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 embodiment 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 an 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 embodiment 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 curve diagram of the optical lens in embodiment 2 of the present invention;

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

fig. 16 is a graph of curvature of field of the 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 embodiment 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 aberrations of an optical lens unit according to 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 diagram 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 embodiment 5 of the present invention;

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

fig. 33 is a MTF graph of an 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 only used 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, in the present application, the embodiments and features of the embodiments 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: 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 surface 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 aperture of the second lens is reduced while the light collection capability of the marginal field of view is improved, and the miniaturization of the volume of the rear end of the optical lens is facilitated; in addition, the vertical axis chromatic aberration caused by overlarge deflection angle of marginal field of view light in the process of transmitting the light from the first lens to the second lens can be effectively avoided, and the difficulty in correcting chromatic aberration of the optical lens is reduced.

In some embodiments, the third lens element may have a concave-convex shape, which is beneficial for converging edge light rays, so that the converged light rays smoothly enter the rear-end optical system, and further the trend of the light rays is approximately parallel to the optical axis, thereby facilitating subsequent correction of aberrations such as chromatic aberration and spherical aberration; 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 element may have a positive focal power, which is beneficial to improving the light converging capability of the peripheral field of view, and at the same time, effectively controlling the total optical length to reduce the volume of the optical lens, thereby being beneficial to the miniaturization of the optical lens. 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 and the seventh lens may have positive focal power and negative focal power or negative focal power and positive focal power, respectively, which is beneficial to balancing various aberrations of the optical lens and improving the imaging quality of the optical lens. The sixth lens and the seventh lens can be respectively provided with a biconvex type and a biconcave type or a biconcave type and a biconvex type, so that the trend of light rays is approximately parallel to the optical axis, and the correction of aberrations such as astigmatism, field curvature and the like is facilitated.

In some embodiments, the eighth lens element may have positive optical power, which is beneficial to suppress the angle of the peripheral field of view incident on the imaging plane, so as to effectively transmit more light beams to the imaging plane and improve the imaging quality of the optical lens. The eighth lens can be of a biconvex 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 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 occurrence of astigmatism in the optical lens, facilitate the collection of light rays 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: FOV is less than or equal to 220 degrees. The method meets the range, is beneficial to realizing the ultra-wide angle characteristic, thereby being capable of acquiring more scene information and meeting 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: 2 DEG < CRA < 20 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. The optical lens satisfies 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: 10 < TTL/f < 14. 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 2.0 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 0.8 and less than 1.5. 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: 3.5 < IH/EPD < 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 angle 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: f1/f is more than-5.5 and less than or equal to-3.0. The first lens has proper 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 is reduced, and the difficulty in correcting the distortion of the rear lens is reduced.

In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -25 < f2/f < -8.0. The second lens has appropriate 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: i f3/f < 700. The third lens has appropriate 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: the | 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 2.5 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: the < 6/f < 2.5. Satisfying the above range, the sixth lens element can have a proper focal power, which is beneficial to balancing spherical aberration, coma, astigmatism and field curvature of the optical lens, and improving the imaging quality of the optical lens.

In some embodiments, the effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: the | f7/f | < 3.0. Satisfying above-mentioned scope, can making the seventh lens have appropriate focal power, be favorable to balancing optical lens's spherical aberration, coma, astigmatism and field curvature, promote optical lens's imaging quality.

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 2.2 and less than 5.2. 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 f13 of the first lens to the third lens satisfy: -5.2 < f13/f < -1.5. The method meets the range, is favorable for converging light rays in a large-angle range to realize an ultra-wide-angle characteristic, 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 combined focal length f67 of the sixth lens and the seventh lens satisfy: -42 < f67/f < -2.5. The cemented lens formed by the combination of the sixth lens and the seventh lens has proper negative focal power, which is beneficial to balancing the chromatic aberration of the optical lens and improving the imaging quality of the optical lens.

In some embodiments, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: f1/f2 is more than 0.2 and less than 0.4. The optical lens has the advantages that the optical lens meets the range, the second lens has smaller focal power compared with the first lens, on the premise that the optical lens has an ultra-wide angle, the phenomenon that the focal power of the first lens is too concentrated to cause overlarge light deflection is avoided, and the difficulty of chromatic aberration correction of the optical lens is reduced.

In some embodiments, the effective focal length f of the optical lens and the object-side and image-side radii of curvature R1 and R2 of the first lens respectively satisfy: r1/f is more than 7.0 and less than 9.5, R2/f is more than 1.7 and less than 2.7. The method meets the range, is beneficial to realizing the ultra-wide angle characteristic, thereby being capable of acquiring more scene information and meeting 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: 4.5 < (R3 + R4)/(R3-R4) < 8.0. 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 third lens object side radius of curvature R5 and the image side radius of curvature R6 satisfy: -22 < (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 effective focal length f of the optical lens and the object-side and image-side radii of curvature R7 and R8 of the fourth lens respectively satisfy: the | R7/f | < 20, and | R8/f | < 50. 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: r9/f is more than 2.0 and less than 3.8, and R10/f is less than 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 focal length f6 of the sixth lens and the object-side and image-side radii of curvature R11 and R12 of the sixth lens, respectively, satisfy: 0.8 < R11/f6 < 4.2, -1.2 < R12/f6 < -0.6. Satisfy above-mentioned scope, be favorable to avoiding the curvature radius of sixth lens objective 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 focal length f7 of the seventh lens and the object side and image side radii of curvature R13 and R14 of the seventh lens, respectively, satisfy: 0.6 < R13/f7 < 2.0, -2.2 < R14/f7 < -1.0. Satisfy above-mentioned scope, be favorable to avoiding the curvature radius of seventh 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 eighth lens object side radius of curvature R15 and the image side radius of curvature R16 satisfy: -15 < (R15-R16)/(R15 + R16) < -1.0. 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 first lens object side radius of curvature R1 and the second lens object side radius of curvature R3 satisfy: R1/R3 is more than 2.2 and less than 4.0. The optical lens system has the advantages that the range is met, the second lens has smaller curvature radius compared with the first lens, the phenomenon that light rays are deflected too much due to too concentrated focal power of the first lens is avoided on the premise that the optical lens system is guaranteed to have an ultra-wide angle, and the difficulty in chromatic aberration correction of the optical lens system is reduced.

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: 1.0mm/rad < (IH/2)/θ < 2.5mm/rad. The optical lens can be balanced between an ultra-wide angle and a large image plane, so that the imaging quality of the optical lens is improved.

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 and 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: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a stop ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, an optical filter G1, and a cover glass G2.

The first lens L1 has negative focal power, and the object side surface S1 of the first lens L is a convex surface, and the image side surface S2 of the first lens L is a concave surface;

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

the third lens L3 has positive focal power, and the object-side surface S5 is a concave surface, and the image-side surface S6 is a convex surface;

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

a diaphragm ST;

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

the sixth lens L6 has positive focal power, and both the object-side surface S11 and the image-side surface S12 are convex surfaces;

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

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

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

the object side surface S17 and the image side surface S18 of the optical filter G1 are both planes;

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

the image formation 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 this embodiment, the curvature of field curve, F-Theta distortion curve, relative illumination curve, MTF curve, axial aberration curve, and vertical axis aberration curve of the optical lens are shown in fig. 2, fig. 3, fig. 4, fig. 5, fig. 6, and fig. 7, respectively.

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 +/-0.35 mm, which indicates that the field curvature of the optical lens is better corrected.

FIG. 3 shows F-Theta distortion curves of example 1, in which F-Theta distortion at different image heights on an image forming plane is shown for light rays of different wavelengths, the horizontal axis shows F-Theta distortion (unit:%), and the vertical axis shows half field angle (unit:%). As can be seen from the figure, the F-Theta distortion of the optical lens is controlled within-40% -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:%). It can be seen from the figure that the relative illuminance value of the optical lens is still greater than 45% at the maximum half field angle, which indicates that the relative illuminance of the optical lens is higher.

Fig. 5 shows MTF (modulation transfer function) graphs of embodiment 1, which represent lens imaging modulation degrees of different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing MTF values. It can be seen from the figure that the MTF value of this embodiment is above 0.45 in the whole field of view, and in the range of 0-90 lp/mm, the MTF curve decreases uniformly and smoothly in the process from the center to the edge field of view, and has good imaging quality and good detail resolution capability in both 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. It can be seen from the figure that 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 +/-5 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: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a stop ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, an optical filter G1, and a cover glass G2.

The first lens L1 has negative focal power, and the object side surface S1 is a convex surface, and the image side surface S2 is a concave surface;

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

a diaphragm ST;

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

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

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 indicates the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis indicating the amount of displacement (unit: mm) and the vertical axis indicating 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 +/-0.12 mm, which indicates that the field curvature of the optical lens is better corrected.

Fig. 10 shows an F-Theta distortion curve of example 2, which represents the F-Theta distortion of light rays of different wavelengths at different image heights on an image forming plane, the horizontal axis representing the F-Theta distortion (unit:%) and the vertical axis representing the half field angle (unit:%). As can be seen from the figure, the F-Theta distortion of the optical lens is controlled within-25% -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 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 40% 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. It can be seen from the figure that the MTF value of this embodiment is above 0.5 in the whole field of view, and in the range of 0-120 lp/mm, the MTF curve decreases uniformly and smoothly in the process from the center to the edge field of view, and has good imaging quality and good detail resolution capability in both 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 ± 0.02mm, 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 +/-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 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: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a stop ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, an optical filter G1, and a cover glass G2.

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

a diaphragm ST;

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

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

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 this embodiment, the curvature of field curve, F-Theta distortion curve, relative illumination curve, MTF curve, axial aberration curve, and vertical axis chromatic aberration curve 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 shows an F-Theta distortion curve of example 3, 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.

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:%). 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. 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. It can be seen from the figure that the MTF value of this embodiment is above 0.5 in the whole field of view, and in the range of 0-90 lp/mm, the MTF curve decreases uniformly and smoothly in the process from the center to the edge field of view, and has good imaging quality and good detail resolution capability in both 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. It can be seen from the figure that the offset of the axial aberration is controlled within ± 0.04mm, 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 +/-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 4

Fig. 22 is a schematic structural view of an optical lens system according to embodiment 4 of the present invention, 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 stop ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, an optical filter G1, and a cover glass G2.

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

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, the curvature of field curve, F-Theta distortion curve, relative illumination curve, MTF curve, axial aberration curve, and vertical axis chromatic aberration curve of the optical lens are respectively shown in fig. 23, fig. 24, fig. 25, fig. 26, fig. 27, and fig. 28.

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 +/-0.06 mm, which indicates that the field curvature of the optical lens is better corrected.

FIG. 24 is a graph showing F-Theta distortion curves of example 4, 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. 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 65% 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 0.4 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 image quality and the detail resolution capability are good 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 ± 0.03mm, 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 +/-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 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: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a stop ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, an optical filter G1, and a cover glass G2.

the fourth lens L4 has negative focal power, and both the object side surface S7 and the image side surface S8 are concave;

a diaphragm ST;

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

TABLE 5-1

The surface shape parameters 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 +/-0.08 mm, which indicates 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-50% -0, 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:%). As can be seen from the figure, the relative illuminance value of the optical lens is still greater than 80% at the maximum half field angle, which indicates that the relative illuminance of the optical lens is high.

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 0.5 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 image quality and the detail resolution capability are good 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 ± 0.025mm, 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 +/-5 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.

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 embodiments of the present invention achieves the effects of a large field angle, a large aperture, a high definition, and a high imaging quality by reasonably matching the lens shapes and focal power combinations among 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:

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 fourth lens having an optical power;

a diaphragm;

a sixth lens having a focal power;

a seventh lens having optical power;

the effective focal length f of the optical lens and the focal length f2 of the second lens meet the following conditions: -25 < f2/f < -8.0;

the effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle satisfy the following conditions: IH/f is more than 2.0 and less than 3.0.

2. The optical lens assembly as claimed in claim 1, wherein the total optical length TTL and the effective focal length f of the optical lens assembly satisfy: 10 < TTL/f < 14.

3. 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 0.8 and less than 1.5.

4. An optical lens according to claim 1, characterized in that the incidence angle CRA on the image plane of the full field chief ray of the optical lens satisfies: 2 DEG < CRA < 20 deg.

5. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: f1/f is more than-5.5 and less than or equal to-3.0.

6. An optical lens according to claim 1, wherein the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: f1/f2 is more than 0.2 and less than 0.4.

7. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the combined focal length f13 of the first to third lenses satisfy: -5.2 < f13/f < -1.5.

8. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the combined focal length f67 of the sixth lens and the seventh lens satisfy: -42 < f67/f < -2.5.

9. An optical lens according to claim 1, wherein the first lens object side radius of curvature R1 and the second lens object side radius of curvature R3 satisfy: R1/R3 is more than 2.2 and less than 4.0.