CN115113379B

CN115113379B - Optical lens

Info

Publication number: CN115113379B
Application number: CN202211044042.6A
Authority: CN
Inventors: 魏文哲; 王克民; 张启灿
Original assignee: Jiangxi Lianchuang Electronic Co Ltd
Current assignee: Jiangxi Lianchuang Electronic Co Ltd
Priority date: 2022-08-30
Filing date: 2022-08-30
Publication date: 2023-01-20
Anticipated expiration: 2042-08-30
Also published as: CN115113379A

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: the first lens with negative focal power has a convex object-side surface and a concave image-side surface; a diaphragm; a second lens having a positive refractive power, the object-side surface of which is convex; a third lens with negative focal power, wherein the image side surface of the third lens is a concave surface; a fourth lens having a positive refractive power, an object-side surface of which is convex; a fifth lens having optical power; a sixth lens having a positive refractive power, an object-side surface of which is convex; a seventh lens having a negative optical power; the effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle satisfy the following conditions: IH/f is less than 0.8. 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 applied 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:

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

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

a diaphragm;

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

a third lens with negative focal power, the image side surface of which is concave;

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

a fifth lens having optical power;

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

a seventh lens having a negative optical power;

the effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle satisfy that: IH/f is less than 0.8.

Preferably, the total optical length TTL and the effective focal length f of the optical lens satisfy: TTL/f is less than 2.0.

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 0.15.

Preferably, the effective focal length f of the optical lens and the focal length f of the first lens element ₁ Satisfies the following conditions: -5.0 < f ₁ /f＜0。

Preferably, the effective focal length f of the optical lens and the focal length f of the fourth lens element ₄ Satisfies the following conditions: f is more than 0 ₄ /f＜5.0。

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: l f ₅ /f|＜4.0。

Preferably, the object side curvature radius R of the first lens ₁ Radius of curvature R of image side surface ₂ Satisfies the following conditions: r is more than 1.0 ₁ /R ₂ ＜1.9。

Preferably, an incident angle CRA of a chief ray of a maximum field angle of the optical lens on an image plane satisfies: 15 DEG < CRA < 28 deg.

Preferably, the effective focal length f, the maximum field angle FOV and the real image height IH corresponding to the maximum field angle of the optical lens satisfy: 0.9 < (IH/2)/(f × tan (FOV/2)) < 1.1.

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

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

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

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

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

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

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

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

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

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

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

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

FIG. 16 is a graph of curvature of field of an optical lens in embodiment 3 of the present invention;

FIG. 17 is a graph showing F-tan θ distortion of an optical lens in embodiment 3 of the present invention;

fig. 18 is a graph showing a relative illuminance curve of the optical lens in embodiment 3 of the present invention;

fig. 19 is a MTF graph of an optical lens in embodiment 3 of the present invention;

FIG. 20 is a graph showing axial aberrations of an optical lens according to embodiment 3 of the present invention;

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

fig. 22 is a schematic structural diagram of an optical lens system according to embodiment 4 of the present invention;

fig. 23 is a graph of curvature of field of the 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 aberrations of an optical lens unit according to embodiment 4 of the present invention;

fig. 28 is a vertical axis chromatic aberration diagram of the optical lens in embodiment 4 of the present invention.

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

Detailed Description

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

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

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

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

It will be further understood that the terms "comprises," "comprising," "has," "having," "includes" and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Moreover, when a statement such as "at least one of" appears after a list of listed features, the entirety of the listed features is modified rather than modifying individual elements in the list. Furthermore, 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 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 embodiments with reference to the attached drawings.

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, a sixth lens and a seventh lens.

In some embodiments, the first lens element may have a negative refractive power, so as to avoid excessive divergence of the object-side light rays, which is beneficial for controlling the aperture of the rear lens element. The object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface, so that incident light can be collected as much as possible, and the relative illumination of the optical lens can be improved.

In some embodiments, the second lens may have a positive focal power, which can balance the spherical aberration generated by the first lens, thereby improving the imaging quality of the optical lens. The object side surface of the second lens is a convex surface, so that the light focusing position reflected by the object side surface of the second lens is positioned behind the imaging surface, the design ghost of the optical lens can be effectively improved, and the imaging quality of the optical lens is improved.

In some embodiments, the third 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 image side surface of the third lens is a concave surface, so that light rays of the marginal field of view can be collected, 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 fourth lens element may have a positive focal power, which is beneficial for converging light rays and reducing the deflection angle of the light rays, so that the light rays are in smooth transition. The object side surface of the fourth lens is a convex surface, so that light rays can be converged, and meanwhile, the relative illumination of the optical lens is improved, the brightness of the optical lens at an image surface is improved, and the dark corner is avoided.

In some embodiments, the sixth lens element may have positive refractive power, which is favorable for converging light rays and reducing the deflection angle of the light rays, so that the light rays are in smooth transition. The object side surface of the sixth lens is a convex surface, so that the relative illumination of the optical lens is improved while light rays are converged, the brightness of the optical lens at the image surface is improved, and the dark corner is avoided.

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.

In some embodiments, the third lens and the fourth lens or the fourth lens and the fifth 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 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 images of the optical lens, and facilitate converging light rays 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 1.60. The range is satisfied, the large aperture characteristic is favorably realized, and the definition of the image 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: 15 DEG < 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 corresponding to the maximum field angle and the effective focal length f of the optical lens satisfy: IH/f is less than 0.8. Satisfying the above range can make the optical lens not only give consideration to the large image plane characteristics, but also have good imaging quality.

In some embodiments, the optical back focus BFL and the effective focal length f of the optical lens satisfy: BFL/f is not more than 0.15. 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 < 1.0 < 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, the maximum field angle FOV, and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: 0.9 < (IH/2)/(f × tan (FOV/2)) < 1.1. The method meets the range, is favorable for controlling the ideal image height to be close to the actual image height, realizes small distortion, reduces image quality adjustment at a module or a product end, and reduces the image quality processing burden of a host.

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: -5.0 < f ₁ The/f is less than 0. Satisfying the above range, the first lens can have a proper negative focal power, and the object-side light can be prevented from being too much diffused, which is beneficial to controlling the aperture of the rear lens.

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 3.0. Satisfying the above range, the second lens can have a proper positive refractive power and can be flatThe spherical aberration generated by the first lens is 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 third lens are ₃ Satisfies the following conditions: -35.0 < f ₃ The/f is less than 0. The third 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 fourth lens are ₄ Satisfies the following conditions: f is more than 0 ₄ The/f is less than 5.0. The fourth lens has proper positive 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: l f ₅ The/| is less than 4.0. The fifth lens has proper focal power, so that the fifth lens is favorable for balancing various aberrations of the optical lens and improving the imaging quality of the optical lens.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the sixth lens ₆ Satisfies the following conditions: f is more than 0 ₆ The/f is less than 30.0. The sixth lens has appropriate positive focal power, light can be smoothly transited, spherical aberration and field curvature of the optical lens are corrected, and imaging quality of the optical lens is improved.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the seventh lens ₇ Satisfies the following conditions: -6.0 < 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 first lens has a radius of curvature of the object side R ₁ Radius of curvature R of image side surface ₂ Satisfies the following conditions: 1.0 < R ₁ /R ₂ Is less than 1.9. The optical lens meets the range, can enable the object side surface and the image side surface of the first lens to obtain similar surface types, can balance the spherical aberration generated by the first lens, and improves the opticsAnd the imaging quality of the lens.

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: 1.0 < D ₁ IH is less than 1.2. The range is satisfied, balance between a large image surface at the imaging end and a small aperture at the object side is obtained, the imaging quality of the optical lens is ensured, and the aperture at the front end 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: 0.45 <. Sigma CT/TTL < 0.7. The optical lens structure meets the range, can effectively compress the total length of the optical lens, and is beneficial to the structural design and the production process of the optical lens.

In order to make the system have better optical performance, a plurality of aspheric lenses are adopted in the lens, and the 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 part of each lens in the optical lens are different, and specific differences can be referred to 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 stop ST, a second lens L2, 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 negative focal power, and the object side surface S1 of the first lens L is a convex surface, and the image side surface S2 of the first lens L is a concave surface;

a diaphragm ST;

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

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

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

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

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

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

the 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.

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 indicates the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis indicating a shift amount (unit: mm) and the vertical axis indicating a half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.06 mm, which indicates that the 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 θ distortion of the optical lens is controlled within ± 6%, which indicates that the optical lens can correct the F-tan θ distortion well.

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 90% 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 ± 60 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 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

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 stop ST, a second lens L2, 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.

a diaphragm ST;

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

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

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

the fifth lens L5 has negative focal power, and both the object-side surface S9 and the image-side surface S10 are concave;

the sixth lens element L6 has positive refractive power, and has a convex object-side surface S11 and a concave 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 fourth lens L4 and the fifth lens L5 may be cemented to constitute a cemented lens.

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

TABLE 2-1

The 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 +/-0.05 mm, which indicates that the optical lens can better correct the field curvature.

Fig. 10 shows an F-tan θ distortion curve of example 2, which shows F-tan θ distortions at different image heights on an image forming plane for light rays of different wavelengths, with the abscissa representing the F-tan θ distortion (unit:%) and the ordinate representing the half field angle (unit: °). As can be seen from the figure, the F-tan θ distortion of the optical lens is controlled within ± 8%, 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 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. 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 ± 40 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 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 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 stop ST, a second lens L2, 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 negative focal power, and the object side surface S1 is a convex surface, and the image side surface S2 is a concave surface;

a diaphragm ST;

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

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

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

the sixth lens element L6 has positive focal power, and has a convex object-side surface S11 and a concave image-side surface S12;

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

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

TABLE 3-1

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

TABLE 3-2

In the present embodiment, a field curvature graph, an F-tan θ distortion curve, a relative illuminance graph, an MTF graph, an axial aberration graph, and a vertical axis chromatic aberration graph of the optical lens are shown in fig. 16, 17, 18, 19, 20, and 21, respectively.

Fig. 16 shows a field curvature curve of example 3, which shows the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis representing the amount of displacement (unit: mm) and the vertical axis representing the half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.08 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 +/-7%, 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:%). It can be seen from the figure that the relative luminance value of the optical lens is still greater than 60% at the maximum half field angle, which indicates that the optical lens has better relative luminance.

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 0.4 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly reduced in the process from the center to the edge field of view, and the image quality and the detail resolution capability are good 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

Referring to fig. 22, a schematic structural diagram of an optical lens system according to embodiment 4 of the present invention is shown, the optical lens system sequentially includes, from an object side to an image plane along an optical axis: a first lens L1, a stop ST, a second lens L2, 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.

a diaphragm ST;

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

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

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

TABLE 4-1

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

TABLE 4-2

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

Fig. 23 shows a field curvature curve of example 4, which shows the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis representing the amount of displacement (unit: mm) and the vertical axis representing the half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.06 mm, which indicates that the optical lens can better correct the field curvature.

Fig. 24 shows an F-tan θ distortion curve of example 4, which shows F-tan θ distortions at different image heights on an image forming plane for light rays of different wavelengths, with the abscissa showing the F-tan θ distortion (unit:%) and the ordinate showing the half field angle (unit: °). As can be seen from the figure, the 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. 25 shows a relative illuminance curve of example 4, which represents relative illuminance values at different angles of field of view on the imaging plane, with the horizontal axis representing the half field angle (unit: °) and the vertical axis representing the relative illuminance (unit:%). As can be seen from the figure, the relative illuminance value of the optical lens at the maximum half field angle is still greater than 70%, indicating that the optical lens has good relative illuminance.

Fig. 26 shows MTF (modulation transfer function) graphs of embodiment 4, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the present embodiment is above 0.4 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly dropped in the process from the center to the edge field of view, and the image quality and the detail resolution are good 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 invention, by reasonably matching the lens shapes and focal power combinations among the lenses, achieves the effects of long focus, miniaturization, low cost, high resolution, and being used in low light and severe environments.

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

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

Claims

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

a diaphragm;

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

a fifth lens having optical power;

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

a seventh lens having a negative optical power;

the effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle satisfy that: IH/f is less than 0.8;

the entrance pupil diameter EPD of the optical lens and the real image height IH corresponding to the maximum field angle satisfy the following conditions: IH/EPD is more than 1.0 and less than 1.3.

2. An optical lens according to claim 1, wherein the total optical length TTL and the effective focal length f satisfy: TTL/f is less than 2.0.

3. 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 more than 0.15.

4. An optical lens as claimed in claim 1, characterized in that the optical lens hasEffective focal length f and focal length f of the first lens ₁ Satisfies the following conditions: -5.0 < f ₁ /f＜0。

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 fourth lens are ₄ Satisfies the following conditions: f is more than 0 ₄ /f＜5.0。

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 fifth lens ₅ Satisfies the following conditions: l f ₅ /f|＜4.0。

7. An optical lens as recited in claim 1, characterized in that the first lens has an object-side radius of curvature R ₁ Radius of curvature R of image side ₂ Satisfies the following conditions: 1.0 < R ₁ /R ₂ ＜1.9。

8. An optical lens according to claim 1, wherein an incident angle CRA on an image plane of a maximum field angle chief ray of the optical lens satisfies: 15 DEG < CRA < 28 deg.

9. The optical lens according to claim 1, wherein the effective focal length f, the maximum field angle FOV and the real image height IH corresponding to the maximum field angle of the optical lens satisfy: 0.9 < (IH/2)/(f × tan (FOV/2)) < 1.1.