CN115236842B

CN115236842B - Optical lens

Info

Publication number: CN115236842B
Application number: CN202211155884.9A
Authority: CN
Inventors: 凌兵兵; 鲍宇旻
Original assignee: Jiangxi Lianchuang Electronic Co Ltd
Current assignee: Jiangxi Lianchuang Electronic Co Ltd
Priority date: 2022-09-22
Filing date: 2022-09-22
Publication date: 2023-02-24
Anticipated expiration: 2042-09-22
Also published as: CN115236842A

Abstract

The invention provides an optical lens, which comprises six lenses in total, and the six lenses are sequentially arranged from an object side to an imaging surface along an optical axis as follows: a first lens having a negative optical power, both the object-side surface and the image-side surface of which are concave; a diaphragm; the image side surface of the second lens is a convex surface; a third lens having positive refractive power, both of an object-side surface and an image-side surface of which are convex surfaces; a fourth lens element having a negative optical power, wherein both the object-side surface and the image-side surface of the fourth lens element are concave; 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 with negative 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 more than 4.0 and less than 5.0. The optical lens has the advantages of large field of view, large aperture and miniaturization.

Description

Optical lens

Technical Field

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

Background

With the development of automobile intelligence, the driving assistance function of the vehicle is gradually enhanced, wherein visual information collection is a core tool. With the increase of the automatic driving level, the requirements on the vehicle-mounted camera are gradually increased, especially for the front camera. The front camera can enhance the active safety and driver assistance functions, such as Automatic Emergency Braking (AEB), adaptive Cruise Control (ACC), lane Keeping Assist System (LKAS), traffic Jam Assist (TJA), and the like, and has the disadvantages of a large number of lenses, an excessively long optical total length, and the like while satisfying the advantages of high resolution, a large field angle, good environmental adaptability, and the like, and is not beneficial to the miniaturization of an electronic system.

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 of view, a large aperture, and a small size.

To achieve the above object, the present invention provides an optical lens, which comprises six lenses, in order from an object side to an image plane along an optical axis:

a first lens having a negative optical power, both the object-side surface and the image-side surface of which are concave;

a diaphragm;

the image side surface of the second lens is a convex surface;

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

a fourth lens element having a negative optical power, wherein both the object-side surface and the image-side surface of the fourth lens element are concave;

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;

a sixth lens element with negative 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 more than 4.0 and less than 5.0.

Preferably, the total optical length TTL of the optical lens and the real image height IH corresponding to the maximum field angle satisfy: TTL/IH is more than 2.5.

Preferably, the optical back focus BFL and the effective focal length f of the optical lens satisfy: BFL/f is not less than 0.7.

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 is more than 2.5 and less than 2.9.

Preferably, the maximum half field angle HFOV of the optical lens satisfies an incident angle CRA of the maximum field angle chief ray on the image plane: 4.0 < HFOV/CRA < 4.5.

Preferably, the effective focal length f of the optical lens and the focal length f of the first lens are equal ₁ Satisfies the following conditions: -1.5 < f ₁ /f＜0。

Preferably, the effective focal length f of the optical lens and the focal length f of the sixth lens element are equal ₆ Satisfies the following conditions: -4.0 < f ₆ /f＜0。

Preferably, the radius of curvature of the image side surface of the third lens element is R ₆ And the object side curvature radius R of the fourth lens ₇ Satisfies the following conditions: r is more than 0.7 ₆ /R ₇ ＜1.3。

Preferably, the image-side surface of the fourth lens has a radius of curvature R ₈ And the object side curvature radius R of the fifth lens ₉ Satisfies the following conditions: r is more than 1.2 ₈ /R ₉ ＜1.5。

Preferably, a real image height IH corresponding to a maximum field angle of the optical lens and an object-side light-transmitting aperture D of the first lens element ₁ Satisfies the following conditions: d is more than 0.8 ₁ /IH＜1.0。

Compared with the prior art, the invention has the beneficial effects that: the optical lens of the application realizes possessing the advantages of large field of view, large aperture and miniaturization through the combination of the lens shape and focal power between each lens of reasonable collocation.

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 the optical lens in embodiment 1 of the present invention;

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

fig. 5 is a MTF graph of 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 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 example 2 of the present invention;

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

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

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

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

fig. 15 is a schematic structural view 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 unit according to embodiment 3 of the present invention;

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

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

Detailed Description

For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of embodiments of the application and does not limit the scope of the application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.

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

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

Herein, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

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

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

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

The optical lens according to the embodiment of the present invention includes, in order from an object side to an image side: the lens comprises a first lens, a diaphragm, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens.

In some embodiments, the first lens may have a negative power, which is beneficial for reducing the inclination angle of the incident light rays, thereby realizing effective sharing of a large field of view of the object space. The object side surface and the image side surface of the first lens are both concave surfaces, so that the effective working caliber of the first lens can be reduced, and the overlarge caliber of the lens behind the optical lens caused by the excessive divergence of light rays can be avoided.

In some embodiments, the second lens 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 trend of the light rays is in smooth transition. The image side surface of the second lens is a convex surface, so that light rays in the marginal field of view can be emitted, and more light rays can be transmitted to the rear end of the optical lens as far as possible.

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 body side and the image side are convex surfaces, so that coma generated by the third lens body can be reduced, and the imaging quality of the optical lens is improved.

In some embodiments, the fourth lens element may have a negative focal power, which is beneficial to increase an imaging area of the optical lens and improve the imaging quality of the optical lens. The object side surface and the image side surface of the fourth lens are both concave surfaces, so that the emergent angle of emergent light rays can be favorably converged, the relative illumination of the optical lens is improved, the brightness of the optical lens at the image surface is improved, and the generation of a dark angle is avoided.

In some embodiments, the fifth 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 object side surface and the image side surface of the fifth lens are convex surfaces, so that coma generated by the fifth lens can be reduced, and the imaging quality of the optical lens is improved.

In some embodiments, the sixth lens element may have a negative focal power, which is beneficial to increase an imaging area of the optical lens and improve the imaging quality of the optical lens. The object side surface of the sixth lens is a convex surface, the image side surface of the sixth lens is a concave surface, so that the emergent angle of emergent light rays can be converged, the relative illumination of the optical lens is improved, the brightness of the optical lens at the image surface is improved, and the generation of a dark angle is avoided; meanwhile, the field curvature generated by the sixth lens can be reduced, and the imaging quality of the optical lens is improved.

In some embodiments, a diaphragm for limiting the light beam may be disposed between the first lens and the second lens, and the diaphragm may be disposed near an object-side surface of the second lens, so as to reduce generation of ghost of the optical lens, and to facilitate converging light entering the optical system and reduce a rear aperture of the optical lens.

In some embodiments, the aperture value FNO of the optical lens satisfies: FNO is less than or equal to 1.64. The range is satisfied, the large aperture characteristic is favorably realized, and the image definition can be ensured in a low-light environment or at night.

In some embodiments, the maximum field angle FOV of the optical lens satisfies: 100 < FOV. The wide-angle detection method meets the range, is beneficial to realizing wide-angle characteristics, can acquire more scene information and meets the requirement of large-range detection.

In some embodiments, the incident angle CRA of the maximum field angle chief ray of the optical lens on the image plane satisfies: CRA < 15 deg. Satisfying above-mentioned scope, can making the tolerance error numerical value between CRA of optical lens and the CRA of chip photosensitive element great, promote optical lens to image sensor's adaptability.

In some embodiments, the total optical length TTL and the effective focal length f of the optical lens satisfy: TTL/f is more than 4.0 and less than 5.0. The optical lens can effectively limit the length of the lens and realize the miniaturization of the optical lens.

In some embodiments, the total optical length TTL of the optical lens and the real image height IH corresponding to the maximum field angle satisfy: TTL/IH is more than 2.5. Satisfying the above range, while taking good image quality into account, is favorable to shortening the total length of the optical lens, and realizes miniaturization of the optical lens.

In some embodiments, the optical back focus BFL and the effective focal length f of the optical lens satisfy: BFL/f is not less than 0.7. 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: 2.5 < IH/EPD < 2.9. The width of the light ray bundle entering the optical lens can be increased, so that the brightness of the optical lens at the image surface is improved, and the dark corner is avoided.

In some embodiments, the maximum half field angle HFOV of the optical lens satisfies: 4.0 < HFOV/CRA < 4.5. The wide-field optical lens has the advantages that the wide-field optical lens can realize large field of view, incident light can enter the image sensor at a proper angle, the light sensitivity of the image sensor is improved, 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 first lens are different ₁ Satisfies the following conditions: -1.5 < f ₁ The/f is less than 0. The first lens has appropriate negative focal power, and is favorable for reducing the inclination angle of incident light, so that the large object field can be effectively shared.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the second lens are different ₂ Satisfies the following conditions: f is more than 0 ₂ The/f is less than 2.5. Satisfy above-mentioned scope, can make the second lens have appropriate positive focal power, be favorable to assembling light and reduce light deflection angle simultaneously, let the light trend smooth transition, promote optical lens's imaging quality.

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: f is more than 0 ₃ The/f is less than 2.5. Satisfying above-mentioned scope, can making the third lens have appropriate positive focal power, be favorable to assembling light and reduce light deflection angle simultaneously, let the light trend smooth transition, promote optical lens's the formation of image quality.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the fourth lens are different ₄ Satisfies the following conditions: -2.0 < f ₄ The/f is less than 0. The fourth lens has appropriate negative focal power, so that the imaging area of the optical lens can be increased, and the imaging quality of the optical lens can be improved.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the fifth lens ₅ Satisfies the following conditions: f is more than 0 ₅ /f＜2.0. Satisfy above-mentioned scope, can make the fifth lens have appropriate positive focal power, be favorable to assembling light and reduce light deflection angle simultaneously, let the light trend smooth transition, promote optical lens's imaging quality.

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: -4.0 < f ₆ The/f is less than 0. The sixth lens has appropriate negative focal power, so that the imaging area of the optical lens can be increased, and the imaging quality of the optical lens can be improved.

In some embodiments, the radius of curvature of the image-side surface of the third lens, R ₆ Radius of curvature R of object side surface of fourth lens ₇ Satisfies the following conditions: r is more than 0.7 ₆ /R ₇ Is less than 1.3. The optical lens system meets the range, can enable the image side surface of the third lens and the object side surface of the fourth lens to obtain similar surface types, is favorable for reducing the influence of field curvature on the optical lens, and improves the imaging quality of the optical lens.

In some embodiments, the fourth lens has a radius of curvature of image side R ₈ And the object side radius of curvature R of the fifth lens ₉ Satisfies the following conditions: 1.2 < R ₈ /R ₉ Is less than 1.5. The optical lens system has the advantages that the image side surface of the fourth lens and the object side surface of the fifth lens can obtain similar surface types, the influence of field curvature on the optical lens is favorably reduced, and the imaging quality of the optical lens is improved.

In some embodiments, the real image height IH corresponding to the maximum field angle of the optical lens and the object-side aperture D of the first lens ₁ Satisfies the following conditions: d is more than 0.8 ₁ IH is less than 1.0. The range is met, balance between a large image plane at the imaging end and a small caliber at the object side is achieved, the imaging quality of the optical lens is guaranteed, and the front-end caliber is reduced.

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 to the seventh lens along the optical axis, respectively, satisfy: 0.7 < ∑ CT/TTL. 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 some embodiments, the sixth lens object sideRise of Sag ₁₁ And the light-transmitting semi-aperture d of the object side surface of the sixth lens ₁₁ Satisfies the following conditions: | Sag ₁₁ /d ₁₁ And | is less than 0.1. Satisfy above-mentioned scope, can effectively retrain the face type in sixth lens body object side off-axis visual field, guarantee that marginal visual field light has sufficient deflection angle when passing through sixth lens, guarantee that the incident angle when light incides to the image forming surface is less to ensure that optical lens has great relative illuminance, promote optical lens's imaging quality.

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

；

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

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

Example 1

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

The first lens L1 has negative focal power, and the object side surface S1 and the image side surface S2 are both concave surfaces;

a diaphragm ST;

the second lens L2 has positive 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;

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

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

the object side surface S13 and the image side surface S14 of the optical filter G1 are both planes;

the image forming surface S15 is a plane.

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

TABLE 1-1

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

Tables 1 to 2

In this embodiment, the curvature of field curve, F-tan θ distortion, relative illumination, MTF, axial aberration, and homeotropic aberration of the optical lens are shown in fig. 2, 3, 4, 5, 6, and 7, respectively.

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

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 F-tan theta distortion of the optical lens is controlled within +/-40%, which shows that 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 0.3 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve uniformly and smoothly drops in the process of the field of view from the center to the edge, and the MTF has better imaging quality and better detail resolution capability under the conditions of low frequency and high frequency.

Fig. 6 shows an axial aberration curve of example 1, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: μm) 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 ± 40 μm, which indicates that the optical lens can correct the axial aberration well.

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 +/-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 2

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

The first lens L1 has negative focal power, and both the object side surface S1 and the image side surface S2 are concave surfaces;

a diaphragm ST;

the second lens L2 has positive focal power, and both the object side surface S3 and the image side surface S4 are convex surfaces;

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

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

TABLE 2-1

The parameters of the surface shape 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 +/-0.11 mm, which shows that the optical lens can better correct the field curvature.

Fig. 10 shows an F-tan θ distortion curve of example 2, 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 F-tan theta distortion of the optical lens is controlled within +/-40%, which shows that 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 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 embodiment is above 0.3 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve uniformly and smoothly drops in the process of the field of view from the center to the edge, and the MTF has better imaging quality and better detail resolution capability under the conditions of low frequency and high frequency.

Fig. 13 shows an axial aberration curve of example 2, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: μm) 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 ± 40 μm, which indicates that the optical lens can correct the axial aberration well.

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 +/-3 mu m, which shows that the optical lens can effectively correct the chromatic aberration of the marginal field of view and the secondary spectrum of the whole image plane.

Example 3

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

a diaphragm ST;

the fourth lens L4 has negative focal power, and both the object-side surface S7 and the image-side surface S8 are concave 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 plane and the sagittal image plane is controlled within +/-0.11 mm, which shows that the optical lens can better 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 of the optical lens is controlled within +/-40%, which shows that 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 0.3 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 has better imaging quality and better detail resolution capability under the conditions of low frequency and high frequency.

Fig. 20 shows an axial aberration curve of example 3, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: 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 ± 20 μm, indicating that the optical lens can correct the axial aberration well.

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.

Please refer to table 4, 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 4

In summary, the optical lens of the embodiments of the invention combines the lens shapes and the focal powers of the lenses reasonably, thereby achieving the advantages of large field of view, large aperture and miniaturization.

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

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

Claims

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

a diaphragm;

the image side surface of the second lens is a convex surface;

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 total optical length TTL and the effective focal length f of the optical lens meet the following requirements: TTL/f is more than 4.0 and less than 5.0;

the total optical length TTL of the optical lens and the real image height IH corresponding to the maximum field angle satisfy the following conditions: 2.5 < TTL/IH.

2. An optical lens according to claim 1, characterized in that the optical back focus BFL of the optical lens and the effective focal length f satisfy: BFL/f is not less than 0.7.

3. The optical lens of claim 1, wherein the entrance pupil diameter EPD of the optical lens and the real image height IH corresponding to the maximum field angle satisfy: 2.5 < IH/EPD < 2.9.

4. The optical lens according to claim 1, wherein an incident angle CRA of a maximum half field angle HFOV of the optical lens with a maximum field angle chief ray on an image plane satisfies: 4.0 < HFOV/CRA < 4.5.

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 first lens are ₁ Satisfies the following conditions: -1.5 < f ₁ /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 sixth lens are ₆ Satisfies the following conditions: -4.0 < f ₆ /f＜0。

7. An optical lens barrel according to claim 1, wherein the third lens has an image side surface curvature radius R ₆ And the object side curvature radius R of the fourth lens ₇ Satisfies the following conditions: r is more than 0.7 ₆ /R ₇ ＜1.3。

8. An optical lens barrel according to claim 1, wherein the fourth lens has an image side surface curvature radius R ₈ And the object side curvature radius R of the fifth lens ₉ Satisfies the following conditions: r is more than 1.2 ₈ /R ₉ ＜1.5。

9. The optical lens assembly as claimed in claim 1, wherein a true image height IH corresponding to a maximum field angle of the optical lens assembly is equal to an object-side aperture diameter D of the first lens ₁ Satisfies the following conditions: d is more than 0.8 ₁ /IH＜1.0。