CN115097615B

CN115097615B - Optical lens

Info

Publication number: CN115097615B
Application number: CN202211016303.3A
Authority: CN
Inventors: 魏文哲; 王克民
Original assignee: Jiangxi Lianchuang Electronic Co Ltd
Current assignee: Jiangxi Lianchuang Electronic Co Ltd
Priority date: 2022-08-24
Filing date: 2022-08-24
Publication date: 2023-01-20
Anticipated expiration: 2042-08-24
Also published as: CN115097615A

Abstract

The invention provides an optical lens, which comprises seven lenses in total, wherein the seven lenses are sequentially arranged from an object side to an imaging surface along an optical axis: a first lens having a positive refractive power, an object-side surface of which is convex; a second lens having a negative optical power; a diaphragm; 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 having positive refractive power, the object-side surface of which is convex; a sixth lens with positive focal power, wherein the image side surface of the sixth lens is a convex surface; a seventh lens having a negative refractive power, an image-side surface of which is concave; the total optical length TTL and the effective focal length f of the optical lens meet the following requirements: TTL/f is less than 2.0. The optical lens has the advantages of long focus, miniaturization, low cost, high resolution and capability of being used in weak light and severe environment.

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), optical lenses have been more widely used and developed. 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.

The focal length of the lens required in the long-distance imaging is longer, but the longer focal length causes the total length of the lens to be longer, which is not beneficial to the miniaturization of the lens. Meanwhile, the lens needs a larger aperture, so that the lens has good imaging quality at night or in an environment with weak illumination conditions. Therefore, it is necessary to develop an optical lens that has a long focus, is small in size, has a low cost, has high resolution, and can be used in a low-light and severe environment.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide an optical lens that has advantages of a long focus, a small size, a low cost, and a high resolution, and can be used in a low-light and severe environment.

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

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

a second lens having a negative optical power;

a diaphragm;

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

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

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

the total optical length TTL and the effective focal length f of the optical lens meet the following requirements: TTL/f is less than 2.0.

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 less than or equal to 0.8.

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 1.0 and less than 1.3.

Preferably, the optical back focus BFL and the effective focal length f of the optical lens satisfy: BFL/f is not less than 0.10.

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: f. of ₂ /f＜-2.5。

Preferably, the effective focal length f of the optical lens and the focal length f of the fifth lens element ₅ Satisfies the following conditions: 2.2 < f ₅ /f＜35.0。

Preferably, the radius of curvature R of the object-side surface of the first lens is ₁ Focal length f of the first lens ₁ Satisfies the following conditions: r is more than 0.6 ₁ /f ₁ ＜0.8。

Preferably, the effective focal length f of the optical lens and the combined focal length f of the first lens and the second lens are equal ₁₂ Satisfies the following conditions: 1.0 < f ₁₂ /f＜1.8。

Preferably, a real image height IH corresponding to a maximum field angle of the optical lens and the object-side aperture diameter D of the first lens element ₁ Satisfies the following conditions: d is more than 0.9 ₁ /IH＜1.3。

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 seventh lens element along the optical axis satisfy: 0.6 <. Sigma CT/TTL < 0.8.

Compared with the prior art, the invention has the beneficial effects that: the optical lens disclosed by the application combines the lens shape and the focal power between the lenses through reasonable collocation, realizes the effects of long focus, miniaturization, low cost, high resolution and use under weak light and severe environment.

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

Drawings

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

fig. 16 is a graph of curvature of field of the 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 illumination of the optical lens in embodiment 4 of the present invention;

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

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

fig. 28 is a vertical axis chromatic aberration diagram of the optical lens system 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 examples or illustrations.

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 second lens, a diaphragm, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens.

In some embodiments, the first lens may have a positive power, which may increase the peripheral field ray collection capability while reducing the working aperture of the first lens. The object side surface of the first lens is a convex surface, so that incident light rays can be collected as much as possible, and the relative illumination of the optical lens is improved.

In some embodiments, the second lens element has a negative focal power, which can balance the spherical aberration generated by the first lens element, thereby improving the imaging quality of the optical lens assembly.

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 object side surface and the image side surface of the third lens are convex surfaces, so that the influence of coma generated by the third lens on the imaging of the optical lens can be reduced, various aberrations of the optical lens are balanced, 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 increasing the imaging area of the optical lens and improving the imaging quality of the optical lens. The object side surface and the image side surface of the fourth lens are both concave surfaces, and light rays of the marginal field of view can be folded, so that various high-order aberrations caused by excessive divergence of the light rays are avoided, and the imaging quality of the optical lens is improved.

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 of the fifth lens is a convex surface, so that marginal field angle light rays can be collected as much as possible, the relative illumination of the optical lens is improved, the brightness of the optical lens at an image surface is improved, and the generation of a dark angle is avoided.

In some embodiments, the sixth lens element may have a positive focal power, which is beneficial for converging light rays and reducing the deflection angle of the light rays, so that the light rays are in smooth transition.

In some embodiments, the seventh lens element may have a negative refractive power, which is beneficial to increase an imaging area of the optical lens and improve the imaging quality of the optical lens. The image side surface of the seventh lens is a concave surface, marginal field-of-view rays can be folded, the incidence angle CRA of the chief ray with the largest field angle on the image surface is compressed, and the adaptability of the optical lens and the image sensor is improved.

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

In some embodiments, a diaphragm for limiting the light beam may be disposed between the second lens and the third lens, and the diaphragm may be disposed near an object-side surface of the third 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 1.6. 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: FOV < 40 deg. The range is met, the long-focus characteristic is facilitated to be realized, so that the far scene information can be acquired, and the requirement of the optical lens on the far scene detection is met.

In some embodiments, the incident angle CRA of the maximum field angle chief ray of the optical lens on the image plane satisfies: CRA < 28 deg. Satisfying the above range, the allowable error value between the CRA of the optical lens and the CRA of the chip photosensitive element can be made larger, and the adaptability of the optical lens to the image sensor can be improved.

In some embodiments, the total optical length TTL and the effective focal length f of the optical lens satisfy: TTL/f is less than 2.0. 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 less than or equal to 0.8. Satisfying the above range can make the optical lens not only give consideration to the characteristics of a large image plane, but also have good imaging quality.

In some embodiments, the optical back focus BFL of the optical lens and the effective focal length f satisfy: BFL/f is not less than 0.10. The method meets the range, is favorable for obtaining balance between good imaging quality and optical back focal length easy to assemble, and reduces the difficulty of the camera module assembly process while ensuring the imaging quality of the optical lens.

In some embodiments, the real image height IH of the optical lens corresponding to the maximum field angle and the entrance pupil diameter EPD satisfy: IH/EPD is more than 1.0 and less than 1.3. 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 effective focal length f of the optical lens and the focal length f of the first lens are different ₁ Satisfies the following conditions: f is more than 0 ₁ The/f is less than 1.5. Satisfying the above range, the first lens can have a proper positive focal power, and the working aperture of the first lens can be reduced while the peripheral field light collection capability can be improved.

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: f. of ₂ And/f is less than-2.5. The second lens has appropriate negative focal power, spherical aberration generated by the first lens can be balanced, 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 third lens are different ₃ Satisfies the following conditions: f is more than 0 ₃ The/f is less than 1.5. Satisfying the above range, the third lens can be made to have a proper valueThe positive focal power is beneficial to reducing the deflection angle of the light while converging the light, so that the trend of the light is in stable transition, 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 fourth lens are different ₄ Satisfies the following conditions: -1.0 < f ₄ The/f is less than 0. The fourth lens has proper negative focal power, the spherical aberration generated by the third lens can be balanced, and the imaging quality of the optical lens is improved.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the fifth lens ₅ Satisfies the following conditions: 2.2 < f ₅ The/f is less than 35.0. Satisfying above-mentioned scope, can making the fifth lens have appropriate positive focal power, be favorable to gathering light and reducing 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 sixth lens element ₆ Satisfies the following conditions: f is more than 0 ₆ The/f is less than 1.5. The sixth lens element has appropriate positive focal power, so that light can be smoothly transited, various aberrations of the optical lens element can be corrected, and the imaging quality of the optical lens element can be 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: -3.5 < f ₇ The/f is less than 0. The seventh lens has appropriate negative focal power, the imaging area of the optical lens can be increased, various aberrations of the optical lens can be corrected, 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 combined focal length f of the first and second lenses ₁₂ Satisfies the following conditions: 1.0 < f ₁₂ The/f is less than 1.8. Satisfying the above range, the lens group at the front end of the diaphragm can have appropriate positive focal power, and the working aperture at the front end of the optical lens can be reduced.

In some embodiments, the radius of curvature R of the object-side surface of the first lens ₁ Focal length f of the first lens ₁ Satisfies the following conditions: r is more than 0.6 ₁ /f ₁ Is less than 0.8. Satisfy the above rangeThe object side surface of the first lens is a convex surface, so that incident light can be collected as much as possible, and the relative illumination 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 0.9 ₁ IH is less than 1.3. 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 to seventh lenses along the optical axis respectively satisfy: 0.6 <. Sigma CT/TTL < 0.8. 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 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: a first lens L1, a second lens L2, a stop ST, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an optical filter G1, and a cover glass G2.

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

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

a diaphragm ST;

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 the object-side surface S9 is a convex surface, and the image-side surface S10 is a concave surface;

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

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

the third lens L3 and the fourth lens L4 can be glued to form a cemented lens;

the object side surface S15 and the image side surface S16 of the optical filter G1 are both planes;

the object side surface S17 and the image side surface S18 of the protective glass G2 are both planes;

the image formation surface S19 is a plane.

Relevant parameters of each lens in the optical lens in embodiment 1 are shown in table 1-1.

TABLE 1-1

The parameters of the surface shape 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 +/-0.04 mm, which indicates that the optical lens can better 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 F-tan theta distortion of the optical lens is controlled within +/-0.4%, which shows that the optical lens can excellently correct the F-tan theta distortion.

Fig. 4 shows a relative illuminance curve of example 1, which represents relative illuminance values at different angles of field of view on the imaging plane, with the horizontal axis representing the half field angle (unit: °) and the vertical axis representing the relative illuminance (unit:%). As can be seen from the figure, the relative illuminance value of the optical lens is still greater than 80% at the maximum half field angle, indicating that the optical lens has excellent relative illuminance.

Fig. 5 shows MTF (modulation transfer function) graphs of embodiment 1, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. It can be seen from the figure that the MTF value of this embodiment is above 0.4 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve decreases uniformly and smoothly in the process from the center to the edge field of view, and has good imaging quality and good detail resolution capability in both low frequency and high frequency.

Fig. 6 shows an axial aberration curve of example 1, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: 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 +/-2 μm, which shows that the optical lens can effectively correct the chromatic aberration of the fringe field and the secondary spectrum of the whole image plane.

Example 2

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

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

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;

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

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

the third lens L3 and the fourth lens L4 may be cemented 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 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 ± 0.06mm, which indicates that the optical lens can correct the field curvature well.

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 θ distortion of the optical lens is controlled within ± 3.0%, indicating that the optical lens can correct the F-tan θ distortion well.

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 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. 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 ± 20 μm, indicating 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 +/-2 mu m, which shows that the optical lens can effectively correct the chromatic aberration of the marginal field of view and the secondary spectrum of the whole image plane.

Example 3

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

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

a diaphragm ST;

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

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

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 +/-0.06 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 +/-6%, 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 +/-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 4

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

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

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

a diaphragm ST;

Relevant parameters of each lens in the optical lens in embodiment 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 +/-0.04 mm, which shows that the optical lens can well correct the field curvature.

Fig. 24 shows an F-tan θ distortion curve of example 4, 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 θ distortion of the optical lens is controlled within ± 2%, which indicates that the optical lens can correct the F-tan θ distortion well.

Fig. 25 shows a relative illuminance curve of example 4, which represents relative illuminance values at different angles of field of view on the imaging plane, with the horizontal axis representing the half field angle (unit: °), and the vertical axis representing the relative illuminance (unit:%). As can be seen from the figure, the relative illuminance value of the optical lens is still greater than 90% at the maximum half field angle, indicating that the optical lens has excellent relative illuminance.

Fig. 26 shows MTF (modulation transfer function) graphs of embodiment 4, which represent lens imaging modulation degrees of different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing MTF values. As can be seen from the figure, the MTF value of the present embodiment is above 0.5 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly dropped in the process from the center to the edge field of view, and the image quality and the detail resolution are excellent in both the low frequency and the high frequency.

Fig. 27 shows an axial aberration curve of example 4, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: 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. 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 +/-2 μm, 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, and the maximum field angle FOV of the optical lens, and the values corresponding to each conditional expression in the embodiments.

TABLE 5

In summary, the optical lens according to the embodiments of the present invention, by reasonably matching the combination of the lens shape and the focal power between the lenses, achieves the effects of both miniaturization and high resolution at a low cost, and can be used in low light and severe environments.

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

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

Claims

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

a second lens having a negative optical power;

a diaphragm;

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 refractive power, both the object-side surface and the image-side surface of which are concave surfaces;

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

the total optical length TTL and the effective focal length f of the optical lens meet the following requirements: TTL/f is less than 2.0;

the real image height IH corresponding to the maximum field angle of the optical lens and the object-side light-transmitting aperture D of the first lens ₁ Satisfies the following conditions: d is more than 0.9 ₁ /IH＜1.3。

2. 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 less than or equal to 0.8.

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: IH/EPD < 1.0 < 1.3.

4. 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 more than or equal to 0.10.

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: f. of ₂ /f＜-2.5。

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 fifth lens are ₅ Satisfies the following conditions: 2.2 < f ₅ /f＜35.0。

7. An optical lens system according to claim 1, characterised in that the radius of curvature R of the object-side surface of the first lens is ₁ Focal length f of the first lens ₁ Satisfies the following conditions: r is more than 0.6 ₁ /f ₁ ＜0.8。

8. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the combined focal length f of the first and second lens are such that ₁₂ Satisfies the following conditions: 1.0 < f ₁₂ /f＜1.8。

9. An optical lens according to claim 1, wherein a total optical length TTL of the optical lens and a sum Σ CT of central thicknesses of the first lens to the seventh lens along an optical axis, respectively, satisfy: 0.6 <. Sigma CT/TTL < 0.8.