CN114815179B

CN114815179B - Optical lens

Info

Publication number: CN114815179B
Application number: CN202210754504.7A
Authority: CN
Inventors: 吴永杰; 魏文哲; 王克民
Original assignee: Jiangxi Lianchuang Electronic Co Ltd
Current assignee: Jiangxi Lianchuang Electronic Co Ltd
Priority date: 2022-06-30
Filing date: 2022-06-30
Publication date: 2022-11-01
Anticipated expiration: 2042-06-30
Also published as: CN114815179A

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; a second lens having a negative refractive power, the object side surface of which is concave; a third lens having a positive refractive power, an object-side surface of which is convex; a diaphragm; a fourth lens having a positive refractive power, an object-side surface of which is convex; a fifth lens element having a positive refractive power, the object-side surface and the image-side surface of the fifth lens element being convex; a sixth lens element having a positive refractive power, wherein both the object-side surface and the image-side surface are convex; a seventh lens having a negative refractive power, an object side surface of which is concave; an eighth lens element with positive refractive power having a convex object-side surface and a concave image-side surface; the total optical length TTL and the effective focal length f of the optical lens meet the following requirements: TTL/f is less than 6.5. The optical lens has the advantages 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 existing wide-angle vehicle-mounted lens can basically meet the basic requirements of the use of the large-field vehicle-mounted lens, various defects still exist, such as small field angle, too small aperture, insufficient resolution 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 realize the purpose, the technical scheme of the invention is as follows:

an optical lens system comprises eight lens elements, 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 having a negative refractive power, the object-side surface of which is concave;

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

a diaphragm;

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

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

a sixth lens element having a positive refractive power, wherein both the object-side surface and the image-side surface are convex;

a seventh lens having a negative refractive power, an object side surface of which is concave;

an eighth lens element with positive refractive power having a convex object-side surface and a concave image-side surface;

the total optical length TTL and the effective focal length f of the optical lens meet the following requirements: TTL/f is less than 6.5;

the effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle satisfy that: 1.9 < IH/f.

Preferably, the optical back focus BFL and the effective focal length f of the optical lens satisfy: BFL/f is not less than 0.6.

Preferably, the entrance pupil diameter EPD of the optical lens and the real image height IH corresponding to the maximum field angle satisfy: IH/EPD < 3.0.

Preferably, the effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle FOV and the maximum field angle satisfy:

。

preferably, the effective focal length f of the optical lens and the focal length f of the first lens element₁Satisfies the following conditions: -1.8 < f₁/f＜0。

Preferably, the effective focal length f of the optical lens and the focal length f of the eighth lens are equal₈Satisfies the following conditions: f is more than 5.0₈/f＜25。

Preferably, the first lens has a radius of curvature of object-side surface R₁Radius of curvature R of image side₂Respectively satisfy: r is more than 1.0₁/ R₂＜4.0。

Preferably, the eighth lens has an object-side radius of curvature R₁₅Radius of curvature R of image side surface₁₆Satisfies the following conditions: -10.0 < (R)₁₅+R₁₆)/(R₁₅-R₁₆)＜-4.0。

Preferably, the sum Σ CT of the thicknesses of all lens centers of the optical lens and the total optical length TTL satisfy: 0.65 < sigma CT/TTL < 0.75.

Compared with the prior art, the invention has the beneficial effects that: the optical lens realizes the effects of large field angle, large aperture, high definition and high imaging quality by reasonably matching the lens shapes and focal power combinations among the lenses.

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-tan θ distortion of an optical lens in example 1 of the present invention;

fig. 4 is a graph showing a relative illumination of an 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 curve diagram of the 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-tan θ distortion of an optical lens in embodiment 2 of the present invention;

fig. 11 is a graph showing a relative illuminance 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-tan θ 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-tan θ 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 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-tan θ distortion of an optical lens in example 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 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, the use of "may" mean "one or more embodiments of the application" when describing embodiments of the 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 accompanying drawings in conjunction with embodiments.

An optical lens according to an embodiment of the present application includes, in order from an object side to an image side: the lens comprises a first lens, a second lens, a third lens, a diaphragm, 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, which is beneficial to obtain a larger field angle range and is beneficial to collect light rays with a large field of view as far as possible into the rear lens. In addition, in practical applications, considering the outdoor installation and use environment of the vehicle-mounted application-type lens, the lens may 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 provided with concave-convex surfaces or double concave surfaces, so that light rays in the edge field of view can be gathered, the gathered light rays can smoothly enter the rear-end optical system, and the trend of the light rays is further in stable transition. In addition, the second lens is set to be in a thick meniscus shape with the convex surface facing the image side, so that the influence of the second lens on the field curvature of the optical lens can be reduced, and the imaging quality of the optical lens is improved.

In some embodiments, the third lens element may have a positive focal power, which is advantageous for converging light rays and reducing the deflection angle of the light rays, so that the light rays are smoothly transitioned. The third lens can be convex-concave or biconvex, so that the energy of a ghost image generated by reflection in the central area of the object side surface of the fourth lens, which is projected on an image surface, can be reduced, and the imaging quality of the optical lens is improved.

In some embodiments, the fourth lens element may have a positive focal power, which is beneficial for converging light rays and reducing the deflection angle of the light rays, so that the light rays are smoothly transited. The fourth lens can be convex-concave or biconvex, and the working caliber of the fourth lens can be further reduced, so that the miniaturization of the volume of the rear end of the optical lens is facilitated, the illumination of the optical lens is improved, and the brightness of the optical lens at the image surface is improved to avoid the generation of a dark angle.

In some embodiments, the fifth lens element may have a positive focal power, which is beneficial for converging light rays and reducing the deflection angle of the light rays, so that the light rays are smoothly transited. The fifth lens element may have a biconvex shape, and the working aperture of the fifth lens element may be further reduced, thereby contributing to the miniaturization of the volume of the rear end of the optical lens.

In some embodiments, the sixth lens element may have a positive focal power, which is beneficial for converging light rays and reducing the deflection angle of the light rays, so that the light rays are smoothly transited. The sixth lens element may have a biconvex shape, and the working aperture of the sixth lens element may be further reduced, thereby contributing to the size reduction of the volume of the rear end of the optical lens.

In some embodiments, the seventh lens element may have a negative focal power, which is beneficial to increase an imaging area of the optical lens, and balance various aberrations generated by the sixth lens element, thereby improving the imaging quality of the optical lens. The seventh lens can be of a biconcave type or a concave-convex type, so that the light ray trend is stable, and the aberration such as astigmatism, field curvature and the like can be corrected conveniently.

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 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 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, an aperture stop for limiting the light beam may be disposed between the third lens and the fourth lens, and the aperture stop may be disposed near an object-side surface of the fourth lens, so as to reduce the generation of astigmatism in the optical lens, and to facilitate the collection of light entering the optical system, thereby reducing the aperture of the rear end of the optical lens.

In some embodiments, the aperture value FNO of the optical lens satisfies: FNO is less than or equal to 1.46. 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: 170 degrees and less than or equal to FOV. The wide-angle detection device has the advantages that the wide-angle characteristic is favorably realized, more scene information can be acquired, and the requirement of large-range detection of the optical lens is met.

In some embodiments, the total optical length TTL and the effective focal length f of the optical lens satisfy: TTL/f is less than 6.5. 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: 1.9 < IH/f. 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 of the optical lens and the effective focal length f satisfy: BFL/f is not less than 0.6. 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 < 3.0. 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 satisfies the following relationship with the maximum field angle FOV and the true image height IH corresponding to the maximum field angle:

，

satisfying the above range can balance the optical lens between a large field angle and high imaging quality.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the first lens are different₁Satisfies the following conditions: -1.8 < f₁The/f is less than 0. Satisfying the above range makes it possible to provide the first lens with an appropriate negative refractive power, which is advantageous for enlarging the field angle of the optical lens.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the second lens₂Satisfies the following conditions: -22 < f₂The/f is less than 0. The second lens has proper negative focal power, can share the negative focal power of the front end of the optical lens, and reduces the difficulty of chromatic aberration correction of the optical lens.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the third lens are₃Satisfies the following conditions: f is more than 0₃And/f is less than 25. Satisfying the above range, the third lens has a proper positive focal power, which is beneficial to smooth transition of light, facilitates correction of astigmatism and curvature of field, and improves imaging quality of the optical lens.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the fourth lens are₄Satisfies the following conditions: f is more than 0₄The/f is less than 7.0. The fourth lens has appropriate positive focal power, so that stable light transition is facilitated, correction of astigmatism and field curvature is facilitated, and imaging quality of the optical lens is improved.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the fifth lens₅Satisfies the following conditions: f is more than 0₅The/f is less than 4.0. The fifth lens has appropriate positive focal power, light smooth transition is facilitated, correction of astigmatism and field curvature is facilitated, and imaging quality of the optical lens is improved.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the sixth lens₆Satisfies the following conditions: f is more than 0₆The/f is less than 2.0. The sixth lens has appropriate positive focal power, so that stable light ray transition is facilitated, correction of astigmatism and curvature of field is facilitated, and imaging quality of the optical lens is improved.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the seventh lens₇Satisfies the following conditions: -2.0 < f7/f < 0. The seventh lens 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 effectiveness of optical lensesFocal length f and focal length f of eighth lens₈Satisfies the following conditions: f is more than 5.0₈And/f is less than 25. The eighth lens has a proper positive 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 focal length f of the sixth lens₆Focal length f of seventh lens₇Satisfies the following conditions: -1.4 < f₆/f₇< -1.0. The method meets the range, is favorable for balancing the chromatic aberration of the optical lens, and improves the imaging quality of the optical lens.

In some embodiments, the first lens has a radius of curvature of the object side R₁Radius of curvature R of image side₂Respectively satisfy: r is more than 1.0₁/ R₂Is less than 4.0. The wide-angle characteristic is favorably realized by meeting the range, so that more scene information can be acquired, and the requirement of large-range detection of an optical lens is met; meanwhile, the distortion generated by the first lens can be reduced as much as possible, the requirement of the subsequent lens on distortion correction is reduced, and the imaging quality of the optical lens is improved.

In some embodiments, the second lens has a radius of curvature of the object side R₃Radius of curvature R of image side surface₄Satisfies the following conditions: -6.0 < (R)₃+R₄)/(R₃-R₄) Is less than 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 effective focal length f of the optical lens and the object-side radius of curvature R of the third lens element₅Radius of curvature R of image side₆Respectively satisfy: 2.0 < R₅/f＜16.0；|R₆The/| is less than 4.0. The optical lens meets the range, is favorable for balancing the off-axis point aberration generated by the third lens, and improves the imaging quality of the optical lens.

In some embodiments, the fourth lens has a radius of curvature of the object side R₇Radius of curvature R of image side₈Satisfies the following conditions: -5.0 < (R)₇-R₈)/(R₇+R₈) Is less than 0. Satisfying the above range, the energy of the ghost image generated by the reflection in the central area of the image side surface of the fourth lens projected on the image plane can be reducedAnd the imaging quality of the optical lens is improved.

In some embodiments, the fifth lens has a radius of curvature of the object side R₉Radius of curvature R of image side surface₁₀Satisfies the following conditions: -4.0 < R₉/R₁₀Is less than 0. The optical lens meets the range, is favorable for balancing the on-axis point aberration generated by the fifth lens, and improves the imaging quality of the optical lens.

In some embodiments, the sixth lens has a radius of curvature of the object side R₁₁Radius of curvature R of image side₁₂Satisfies the following conditions: -2.5. Ltoreq.R₁₁/R₁₂< -1.0. Satisfy above-mentioned scope, can control the shape of sixth lens object side and image side, make it more be close to the concentric circles structure, be favorable to the smooth transition of light trend, can balance optical lens's all kinds of aberrations effectively, promote optical lens's imaging quality.

In some embodiments, the seventh lens has a radius of curvature of object side R₁₃Radius of curvature R of image side surface₁₄Satisfies the following conditions: -2.0 < (R)₁₃-R₁₄)/(R₁₃+R₁₄) Is less than 0. The range is satisfied, the image plane size of the optical lens can be controlled, and the balance between high imaging quality and large image plane characteristic of the optical lens is favorably achieved.

In some embodiments, the eighth lens has an object side radius of curvature R₁₅Radius of curvature R of image side surface₁₆Satisfies the following conditions: -10.0 < (R)₁₅+R₁₆)/(R₁₅-R₁₆) < -4.0. The method meets the range, is favorable for balancing the astigmatism and the field curvature of the optical lens, and improves the imaging quality of the optical lens.

In some embodiments, the sum Σ CT of all lens center thicknesses of the optical lens and the total optical length TTL satisfy: 0.65 < sigma CT/TTL < 0.75. Satisfying the above range is advantageous for shortening the total length of the optical 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 direction of the optical axis, 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 the coefficient of the quadric surface, and A, B, C, D, E, F are the coefficients of the second-order, fourth-order, sixth-order, eighth-order, tenth-order and twelfth-order curved surfaces, 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 stop ST, a fourth lens L4, 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 second lens L2 has negative focal power, and the object side surface S3 is a concave surface, and the image side surface S4 is a convex surface;

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

a diaphragm ST;

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

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 element L7 has negative power, and has a concave object-side surface S13 and a convex image-side surface S14;

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

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 the present embodiment, a field curvature graph, an F-tan θ 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 +/-0.022 mm, which shows that the optical lens can excellently correct the field curvature.

Fig. 3 shows an F-tan θ distortion curve of example 1, which shows F-tan θ distortions at different image heights on an image forming plane for light rays of different wavelengths, with the abscissa representing the F-tan θ distortion (unit:%) and the ordinate representing the half field angle (unit: °). As can be seen from the figure, the distortion curve trend of the F-tan theta of the optical lens is smooth, the image compression of the edge large-angle area is smooth, the definition of the expanded image is effectively improved, and the optical lens can better correct the F-tan theta distortion.

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 80% at the maximum half field angle, indicating that the optical lens has excellent relative illuminance.

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 present embodiment is above 0.5 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly dropped in the process from the center to the edge field of view, and the image quality and the detail resolution capability are excellent in both the low frequency and the 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 shift amount of the axial aberration is controlled within ± 0.016mm, which indicates that the optical lens can excellently 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 stop ST, a fourth lens L4, 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 second lens L2 has negative focal power, the object side surface S3 is a concave surface, and the image side surface S4 is a convex surface;

the third lens L3 has positive focal power, and both the object side surface S5 and the image side surface S6 are convex surfaces;

a diaphragm ST;

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

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 this embodiment, the curvature of field curve, F-tan θ 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. 9, 10, 11, 12, 13, and 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 surface and the sagittal image surface is controlled within +/-0.024 mm, which shows that the optical lens can excellently correct the field curvature.

Fig. 10 shows an F-tan θ distortion curve of example 2, which shows F-tan θ distortions at different image heights on an image forming plane for light rays of different wavelengths, with the abscissa representing the F-tan θ distortion (unit:%) and the ordinate representing the half field angle (unit: °). As can be seen from the figure, the distortion curve trend of the F-tan theta of the optical lens is smooth, the image compression of the edge large-angle area is smooth, the definition of the expanded image is effectively improved, and the optical lens can better correct the F-tan theta distortion.

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 luminance value of the optical lens is still greater than 80% at the maximum half field angle, indicating that the optical lens has excellent relative luminance.

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 present embodiment is above 0.5 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly dropped in the process from the center to the edge field of view, and the image quality and the detail resolution capability are excellent in both the low frequency and the 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 excellently 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 +/-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 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 stop ST, a fourth lens L4, 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.

a diaphragm ST;

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

Relevant parameters of each lens in the optical lens in embodiment 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-tan θ distortion curve, 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 surface and the sagittal image surface is controlled within +/-0.024 mm, which shows that the optical lens can excellently correct the field curvature.

Fig. 17 shows an F-tan θ distortion curve of example 3, which shows F-tan θ distortions at different image heights on an image forming plane for light rays of different wavelengths, with the abscissa representing the F-tan θ distortion (unit:%) and the ordinate representing the half field angle (unit: °). As can be seen from the figure, the F-tan theta curve trend of the optical lens is smooth, the image compression in the edge large-angle area is smooth, the definition of the expanded image is effectively improved, and the optical lens can better correct the F-tan theta distortion.

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 80% at the maximum half field angle, indicating that the optical lens has excellent relative illuminance.

Fig. 19 shows MTF (modulation transfer function) graphs of embodiment 3, 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. As can be seen from the figure, the MTF value of the present embodiment is above 0.5 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly dropped in the process from the center to the edge field of view, and the image quality and the detail resolution capability are excellent in both the low frequency and the 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 amount of displacement of the axial aberration is controlled within ± 0.022mm, which indicates that the optical lens can excellently 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 +/-4 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 stop ST, a fourth lens L4, 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;

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 parameters of the surface shape 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-tan θ distortion curve, 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 +/-0.028 mm, which shows that the optical lens can excellently correct the field curvature.

Fig. 24 shows an F-tan θ distortion curve of example 4, which shows F-tan θ distortions at different image heights on an image forming plane for light rays of different wavelengths, with the abscissa showing the F-tan θ distortion (unit:%) and the ordinate showing the half field angle (unit: °). As can be seen from the figure, the distortion curve trend of the F-tan theta of the optical lens is smooth, the image compression of the edge large-angle area is smooth, the definition of the expanded image is effectively improved, and the optical lens can better correct the F-tan theta distortion.

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 80% at the maximum half field angle, indicating that the optical lens has excellent relative illuminance.

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 present embodiment is above 0.4 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly dropped in the process from the center to the edge field of view, and the image quality and the detail resolution are excellent in both the low frequency and the 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 ± 0.012mm, which indicates that the optical lens can excellently 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 excellently correct the chromatic aberration of the marginal field of view and the secondary spectrum of the whole image surface.

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 stop ST, a fourth lens L4, 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 second lens L2 has negative focal power, and both the object side surface S3 and the image side surface S4 are concave surfaces;

a diaphragm ST;

Relevant parameters of each lens in the optical lens in embodiment 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-tan θ distortion curve, 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 surface and the sagittal image surface is controlled within +/-0.024 mm, which shows that the optical lens can excellently correct the field curvature.

Fig. 31 shows an F-tan θ distortion curve of example 5, which shows the F-tan θ distortion of light rays of different wavelengths at different image heights on an image forming plane, with the horizontal axis showing the F-tan θ distortion (unit:%) and the vertical axis showing the half field angle (unit:%). As can be seen from the figure, the distortion curve trend of the F-tan theta of the optical lens is smooth, the image compression of the edge large-angle area is smooth, the definition of the expanded image is effectively improved, and the optical lens can better correct the F-tan theta distortion.

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 luminance value of the optical lens at the maximum half field angle is still greater than 70%, indicating that the optical lens has good relative luminance.

Fig. 33 shows a Modulation Transfer Function (MTF) graph of example 5, which represents the lens imaging modulation degree for 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 present embodiment is above 0.5 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly dropped in the process from the center to the edge field of view, and the image quality and the detail resolution are excellent in both the low frequency and the 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 ± 0.02mm, which indicates that the optical lens can excellently 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 +/-7 mu m, which shows that the optical lens can well 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 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 among the lenses.

In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means 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;

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

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

a diaphragm;

a fourth 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 real image height IH corresponding to the maximum field angle satisfy that: IH/f is more than 1.9.

2. 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 not less than 0.6.

3. The optical lens of claim 1, wherein an entrance pupil diameter EPD of the optical lens satisfies a real image height IH corresponding to a maximum field angle: IH/EPD < 3.0.

4. The optical lens according to claim 1, wherein the effective focal length f of the optical lens satisfies the following relationship with the real image height IH corresponding to the maximum field angle FOV and the maximum field angle:

。

5. an optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f of the first lens are₁Satisfies the following conditions: -1.8 < f₁/f＜0。

6. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f of the eighth lens₈Satisfies the following conditions: f is more than 5.0₈/f＜25。

7. An optical lens as recited in claim 1, wherein the first lens object side radius of curvature R₁Radius of curvature R of image side₂Respectively satisfy: r is more than 1.0₁/ R₂＜4.0。

8. An optical lens barrel according to claim 1, wherein the eighth lens object side radius of curvature R₁₅Radius of curvature R of image side surface₁₆Satisfies the following conditions: -10.0 < (R)₁₅+R₁₆)/(R₁₅-R₁₆)＜-4.0。

9. An optical lens according to claim 1, wherein the sum Σ CT of all lens center thicknesses and total optical length TTL of the optical lens satisfy: 0.65 < sigma CT/TTL < 0.75.