CN115016105A

CN115016105A - Optical lens

Info

Publication number: CN115016105A
Application number: CN202210935120.5A
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: 2022-08-05
Filing date: 2022-08-05
Publication date: 2022-09-06
Anticipated expiration: 2042-08-05
Also published as: CN115016105B

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: a front lens group with positive focal power, a diaphragm, a rear lens group with positive focal power; the front lens group includes: a first lens having a negative refractive power, a second lens having a positive refractive power, a third lens having a positive refractive power, a fourth lens having a positive refractive power, a fifth lens having a positive refractive power; the rear lens group includes: a sixth lens having positive power, a seventh lens having negative power, an eighth lens having positive power; combined focal length f of front lens group _{Front side} And the combined focal length f of the rear lens group _{Rear end} And the effective focal length f respectively satisfy: f is more than 0 _{Front side} /f＜1.3；6.0＜f _{Rear end} The/f is less than 9.0. 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 using the large-field vehicle-mounted lens, the existing wide-angle vehicle-mounted lens still has many defects, such as small field angle, too small aperture, insufficient resolving power 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.

To achieve the above object, the present invention provides an optical lens system, comprising eight lenses, in order from an object side to an image plane along an optical axis:

the lens comprises a front lens group with positive focal power, a diaphragm and a rear lens group with positive focal power;

wherein the front lens group includes: the first lens with negative focal power has a convex object-side surface and a concave image-side surface; a second lens having a focal power, wherein the object-side surface of the second lens is a concave surface, and the image-side surface of the second lens is a convex surface; a third lens with positive focal power, wherein the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface; 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;

the rear lens group includes: 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;

combined focal length f of the front lens group _{Front side} And the combined focal length f of the rear lens group _{Rear end} And the effective focal length f respectively satisfy: f is more than 0 _{Front part} /f＜1.3，6.0＜f _{Rear end} /f＜9.0。

Preferably, the total optical length TTL and the effective focal length f of the optical lens satisfy: TTL/f is less than 6.5.

Preferably, the effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle satisfy: IH/f is more than 1.9.

Preferably, the optical back focus BFL and the effective focal length f of the optical lens satisfy: BFL/f is more than 0.5.

Preferably, the effective focal length f of the optical lens and the second focal length fFocal length f of two lenses ₂ Satisfies the following conditions: l f ₂ /f|＜130。

Preferably, the second lens has positive optical power.

Preferably, the effective focal length f of the optical lens and the focal length f of the second lens are equal ₂ Satisfies the following conditions: 20 < f ₂ /f＜130。

Preferably, the total optical length TTL of the optical lens and the center thickness CT of the second lens element ₂ Satisfies the following conditions: 0.11 < CT ₂ /TTL＜0.22。

Preferably, the total optical length TTL of the optical lens and the sum Σ CT of the central thicknesses of the first lens element to the eighth lens element along the optical axis satisfy: 0.5 <. sigma CT/TTL < 0.7.

Preferably, the third lens and the fourth lens are cemented together to form a cemented lens, and the sixth lens and the seventh lens are cemented together to form a cemented lens.

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 illuminance curve of the optical lens in embodiment 1 of the present invention;

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

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

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

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

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

FIG. 10 is a graph showing F-tan θ distortion of an optical lens in example 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 curve diagram of the 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 aberrations of an optical lens unit according to embodiment 4 of the present invention;

fig. 28 is a vertical axis chromatic aberration diagram of the optical lens in embodiment 4 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, 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: the lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a diaphragm, a sixth lens, a seventh lens and an eighth lens. The eight lenses form a front lens group with positive focal power and a rear lens group with positive focal power; the front lens group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens, and the rear lens group comprises 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 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 may have a concave-convex shape, which is beneficial for converging light rays in the edge field of view, so that the converged light rays smoothly enter the rear-end optical system, and further the trend of the light rays is in smooth 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 of a convex-concave surface type, so that the energy of a ghost image generated by reflection in the central area of the object side surface of the fourth lens on the 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 in smooth transition. The fourth lens can be convex-concave or biconvex, which is beneficial to improving the illumination of the optical lens, so that the brightness of the optical lens at an image surface is improved, and the generation of a dark corner is avoided.

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 in smooth transition. 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 positive refractive power, which is favorable for converging light rays and reducing the deflection angle of the light rays, so that the light rays are in smooth transition. 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 the 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 or concave-convex surface type, so that the smooth trend of light rays is facilitated, 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 convex-concave type, so that the relative illumination of the edge field of view can be improved, the generation of a dark corner can be avoided, and the imaging quality of the optical lens can be improved.

In some embodiments, the third lens, the fourth lens, 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 stop for limiting the light beam may be disposed between the fifth lens and the sixth lens, and the stop may be disposed near an image side surface of the fifth lens, so as to reduce the occurrence of astigmatism of the optical lens, and to facilitate the collection of light entering the optical system and reduce 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: IH/f is more than 1.9. 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 0.5. 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 combined focal length f of the front lens group of the optical lens _{Front part} And the combined focal length f of the rear lens group _{Rear end} And the effective focal length f respectively satisfy: f is more than 0 _{Front side} /f＜1.3，6.0＜f _{Rear end} The/f is less than 9.0. Satisfying the above range, on the one hand, it is favorable to controlling the incident ray height of the front lens group to reduce the high-order aberration and the mechanical aperture of the lens, and on the other hand, it can reduce the exit angle of the chief ray passing through the rear lens group to improve the relative illumination of the optical lens.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the first lens are different ₁ Satisfies the following conditions: -2.0. ltoreq. f ₁ The/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 lens ₂ Satisfies the following conditions: l f ₂ And/f < 130. The optical lens meets the range, can enable the second lens to have proper focal power, can balance the negative focal power at the front end of the optical lens, and reduces the difficulty of chromatic dispersion 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 are ₃ Satisfies the following conditions: 12 < f ₃ The/f is less than 55. Satisfying the above range, the third lens element can have a proper positive focal power, which is favorable for smooth transition of light and astigmatismAnd the field curvature correction improves the 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 are ₄ Satisfies the following conditions: f is more than 0 ₄ The/f is less than 6.0. Satisfying the above range, the fourth 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 fifth lens ₅ Satisfies the following conditions: f is more than 0 ₅ The/f is less than 4.0. The fifth 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 sixth lens element ₆ Satisfies the following conditions: f is more than 0 ₆ The/f is less than 1.5. 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 lens ₇ Satisfies the following conditions: -1.5 < f ₇ The/f is less than 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 effective focal length f of the optical lens and the focal length f of the eighth lens ₈ Satisfies the following conditions: f is more than 0 ₈ The/f is less than 11.0. The eighth lens element has a proper positive focal power, so that astigmatism and curvature of field 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 radius of curvature R of the object-side surface of the first lens element ₁ Satisfies the following conditions: -1.5 < R ₁ And/f is less than-0.5. The range is satisfied, the receiving of the light rays with large angles is facilitated, and meanwhile, the distortion of the optical lens is reduced.

In some embodiments, an optical lensThe total optical length TTL and the center thickness CT of the second lens ₂ Satisfies the following conditions: 0.11 < CT ₂ TTL is less than 0.22. The field curvature of the optical lens can be corrected, and the imaging quality of the optical lens can be improved.

In some embodiments, the refractive index Nd of the sixth lens ₆ Refractive index Nd of seventh lens ₇ And Abbe number Vd of sixth lens ₆ Abbe number Vd of seventh lens ₇ Respectively satisfy: nd 0.9 < ₆ /Nd ₇ ＜0.95；2.0＜Vd ₆ /Vd ₇ Is less than 2.3. The chromatic aberration correction method meets the range, is favorable for correcting chromatic aberration of the optical lens, and improves imaging quality of the optical lens.

In some embodiments, the total optical length TTL of the optical lens and the sum Σ CT of the central thicknesses of the first lens element to the eighth lens element along the optical axis respectively satisfy: 0.5 <. sigma CT/TTL < 0.7. The optical lens structure meets the range, can effectively compress the total length of the optical lens, and is beneficial to the structural design and the production process 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 shapes of the aspheric surfaces of the optical lens satisfy the following equation:

；

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

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

Example 1

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

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

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

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

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

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

a diaphragm ST;

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

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

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

the third lens L3 and the fourth lens L4, the sixth lens L6 and the seventh lens L7 can be cemented together to form a cemented lens;

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

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

the image forming surface S21 is a plane.

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

TABLE 1-1

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

Tables 1 to 2

In the present embodiment, a 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 +/-0.03 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 at the maximum half field angle is still greater than 70%, indicating that the optical lens has good 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 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 reduced in the process from the center to the edge field of view, and the image quality and the detail resolution capability are excellent under the conditions of low frequency and high frequency.

Fig. 6 shows an axial aberration curve of example 1, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: μm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the amount of shift of the axial aberration is controlled within ± 10 μm, indicating 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 provided in embodiment 2 is shown, the optical lens system sequentially includes, from an object side to an image plane along an optical axis: the lens system includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a stop ST, a sixth lens L6, a seventh lens L7, an eighth lens L8, a filter G1, and a protective glass G2.

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

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

a diaphragm ST;

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

the third lens L3 and the fourth lens L4, the sixth lens L6 and the seventh lens L7 can be cemented together to form a cemented lens.

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

TABLE 2-1

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

Tables 2 to 2

In the present embodiment, a field curvature graph, an F-tan θ distortion curve, 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. 9, fig. 10, fig. 11, fig. 12, fig. 13, and fig. 14.

Fig. 9 shows a field curvature curve of example 2, which shows the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis representing the amount of displacement (unit: mm) and the vertical axis representing the half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.03 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 illuminance value of the optical lens at the maximum half field angle is still greater than 70%, indicating that the optical lens has good relative illuminance.

Fig. 12 shows MTF (modulation transfer function) graphs of embodiment 2, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.5 in the whole field of view, and in the range of 0-160 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 excellent under the conditions of low frequency and high frequency.

Fig. 13 shows an axial aberration curve of example 2, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: μm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the amount of shift of the axial aberration is controlled within ± 10 μm, indicating 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 provided in embodiment 3 is shown, the optical lens system sequentially includes, from an object side to an image plane along an optical axis: the lens comprises a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a diaphragm ST, a sixth lens L6, a seventh lens L7, an eighth lens L8, a filter G1 and protective glass G2.

a diaphragm ST;

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

TABLE 3-1

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

TABLE 3-2

In the present embodiment, a field curvature graph, an F-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 plane and the sagittal image plane is controlled within +/-0.03 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 distortion curve of the optical lens is smooth in trend, 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 at the maximum half field angle is still greater than 70%, indicating that the optical lens has good relative illuminance.

Fig. 19 shows MTF (modulation transfer function) graphs of embodiment 3, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.5 in the whole field of view, and in the range of 0-160 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 excellent under the conditions of low frequency and high frequency.

Fig. 20 shows an axial aberration curve of example 3, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: μm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the amount of shift of the axial aberration is controlled within ± 10 μm, indicating 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 +/-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 4

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

a diaphragm ST;

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

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

TABLE 4-1

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

TABLE 4-2

In the present embodiment, a field curvature graph, an F-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 +/-0.02 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 at the maximum half field angle is still greater than 70%, indicating that the optical lens has good 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 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 reduced in the process from the center to the edge field of view, and the image quality and the detail resolution capability are excellent 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: μm) 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 ± 12 μm, 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 +/-5 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.

Please refer to table 5, 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, the maximum field angle FOV, the chief ray image plane incident angle CRA, and the values corresponding to each conditional expression in the embodiments.

TABLE 5

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 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 embodiments only show several embodiments of the present invention, and the description is specific and detailed, but not construed as limiting the scope of the present 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:

wherein the front lens group includes: the first lens with negative focal power has a convex object-side surface and a concave image-side surface; a second lens having a focal power, wherein the object-side surface of the second lens is a concave surface, and the image-side surface of the second lens is a convex surface; a third lens with positive focal power, wherein the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface; a fourth lens having a positive refractive power, an object-side surface of which is convex; a fifth lens element having positive refractive power, both the object-side surface and the image-side surface of the fifth lens element being convex;

combined focal length f of the front lens group _{Front side} And the combined focal length f of the rear lens group _{Rear end} And the effective focal length f respectively satisfy: f is more than 0 _{Front side} /f＜1.3，6.0＜f _{Rear end} /f＜9.0。

2. An optical lens according to claim 1, wherein the total optical length TTL and the effective focal length f satisfy: TTL/f is less than 6.5.

3. The optical lens according to claim 1, wherein a real image height IH of the optical lens corresponding to an effective focal length f and a maximum field angle satisfies: IH/f is more than 1.9.

4. An optical lens according to claim 1, characterized in that the optical back focus BFL and the effective focal length f of the optical lens satisfy: BFL/f is more than 0.5.

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 second lens are ₂ Satisfies the following conditions: l f ₂ /f|＜130。

6. An optical lens according to claim 1, characterized in that: the second lens has a positive optical power.

7. An optical lens according to claim 6, characterized in that the effective focal length f of the optical lens and the focal length f of the second lens are ₂ Satisfies the following conditions: 20 < f ₂ /f＜130。

8. An optical lens as claimed in claim 6, characterized in that the total optical length TTL of the optical lens and the center thickness CT of the second lens element ₂ Satisfies the following conditions: 0.11 < CT ₂ /TTL＜0.22。

9. An optical lens according to claim 1 or 6, wherein a total optical length TTL of the optical lens and a sum Σ CT of central thicknesses of the first lens to the eighth lens along an optical axis, respectively, satisfy: 0.5 <. sigma CT/TTL < 0.7.

10. An optical lens according to claim 1 or 6, wherein the third lens and the fourth lens are cemented together to form a cemented lens, and the sixth lens and the seventh lens are cemented together to form a cemented lens.