CN114415348A

CN114415348A - Optical lens

Info

Publication number: CN114415348A
Application number: CN202210321006.3A
Authority: CN
Inventors: 陈星星; 陈伟建; 王克民; 曾吉勇
Original assignee: Jiangxi Lianchuang Electronic Co Ltd
Current assignee: Jiangxi Lianchuang Electronic Co Ltd
Priority date: 2022-03-30
Filing date: 2022-03-30
Publication date: 2022-04-29
Anticipated expiration: 2042-03-30
Also published as: CN114415348B

Abstract

The invention provides an optical lens, which comprises five lenses in total, and the five 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; the second lens with positive focal power has a concave object-side surface and a convex image-side surface; a third lens having a negative optical power; a fourth lens having a positive refractive power, both the object-side surface and the image-side surface of the fourth lens being convex; a fifth lens element with negative refractive power having a convex object-side surface and a concave image-side surface; the field angle FOV and the aperture value FNO of the optical lens meet the following conditions: 120 DEG < FOV/FNO < 150 deg. The optical lens has the advantages of large field angle, large aperture and high resolution.

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 fields such as unmanned aerial vehicles, security, automobiles, meteorology and medical treatment, higher and higher requirements are also put forward on the field angle of the lens carried by the unmanned aerial vehicle. The wide-angle lens compresses light rays in the edge field of view as much as possible by introducing barrel distortion, and further realizes the ultra-wide-angle lens with the field angle exceeding 180 degrees. At present, many problems still exist in the super wide-angle lens, for example, the common super wide-angle lens aperture is less, can cause the camera lens quantity of light entering not enough, the formation of image is unclear, in addition, the aberration correction degree of difficulty is big, the image plane is generally less etc.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide an optical lens having advantages of a large field angle, a large aperture, a small chromatic aberration, and a high resolution.

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

the invention provides an optical lens, which comprises five lenses in total, and sequentially comprises the following components 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; the second lens with positive focal power has a concave object-side surface and a convex image-side surface; a third lens having a negative optical power; a fourth lens having a positive refractive power, both the object-side surface and the image-side surface of the fourth lens being convex; a fifth lens element with negative refractive power having a convex object-side surface and a concave image-side surface;

the field angle FOV and the aperture value FNO of the optical lens meet the following conditions: 120 DEG < FOV/FNO < 150 deg.

Preferably, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: i f1+ f 2I < 1.0.

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 more than 3.0 and less than 3.5.

Preferably, the total optical length TTL of the optical lens and the real image height IH corresponding to the maximum field angle satisfy: TTL/IH is less than 3.1.

Preferably, the incident angle CRA on the image plane of the full-field chief ray of the optical lens satisfies: 30 DEG < CRA < 40 deg.

Preferably, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -5.0 < f1/f < 0.

Preferably, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: f2/f is more than 0 and less than 4.0.

Preferably, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: -3.0 < f3/f < -1.5.

Preferably, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: f4/f is more than 1.2 and less than 1.8.

Preferably, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -40 < f5/f < 0.

Compared with the prior art, the invention has the beneficial effects that: the optical lens disclosed by the application has the advantages of large field angle, large aperture and high resolving power by reasonably matching the lens shapes and focal power combinations among the lenses.

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

Drawings

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

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

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

fig. 3 is a graph showing a relative illuminance curve of the optical lens in embodiment 1 of the present invention;

fig. 4 is a MTF graph of the optical lens in embodiment 1 of the present invention;

FIG. 5 is a graph showing axial aberrations of an optical lens system according to embodiment 1 of the present invention;

FIG. 6 is a vertical axis chromatic aberration diagram of an optical lens in embodiment 1 of the present invention;

fig. 7 is a schematic structural diagram of an optical lens system according to embodiment 2 of the present invention;

FIG. 8 is a graph of curvature of field of an optical lens in embodiment 2 of the present invention;

fig. 9 is a graph showing a relative illuminance curve of an optical lens in embodiment 2 of the present invention;

fig. 10 is a MTF graph of an optical lens in embodiment 2 of the present invention;

fig. 11 is a graph showing axial aberration of the optical lens in embodiment 2 of the present invention;

FIG. 12 is a vertical axis chromatic aberration diagram of an optical lens in embodiment 2 of the present invention;

fig. 13 is a schematic structural diagram of an optical lens system according to embodiment 3 of the present invention;

FIG. 14 is a graph of curvature of field of an optical lens in embodiment 3 of the present invention;

fig. 15 is a graph showing a relative illuminance curve of the optical lens in embodiment 3 of the present invention;

fig. 16 is a MTF graph of the optical lens in embodiment 3 of the present invention;

fig. 17 is a graph showing axial aberration of the optical lens in embodiment 3 of the present invention;

fig. 18 is a vertical axis chromatic aberration diagram of the optical lens in embodiment 3 of the present invention.

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

Detailed Description

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

It should be noted that in this specification, the expressions first, second, third, etc. are 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. Further, when a statement such as "at least one of" appears after a list of listed features, the entire listed feature is modified rather than modifying individual elements in the list. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.

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

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

An optical lens according to an embodiment of the present application includes, in order from an object side to an image side: the lens includes a first lens, a second lens, a third lens, a fourth lens and a fifth lens.

In some embodiments, the first lens may have a negative power, which is beneficial for reducing the inclination angle of the incident light, thereby achieving effective sharing of a large field of view of the object. The first lens can be of a convex-concave surface type, so that a larger field angle range is obtained, and the condition that light rays with a large field of view are collected into the rear lens as much as possible is increased. In addition, in practical application, considering the outdoor installation and use environment of the vehicle-mounted application-type lens, the lens can be in severe weather such as rain, snow and the like, and the first lens is set to be in a meniscus shape with the convex surface facing the object side, so that water drops and the like can slide off favorably, and the influence on the imaging of the optical lens can be reduced.

In some embodiments, the second lens element may have a positive refractive power, which is beneficial to balance the off-axis aberration caused by the first lens element, thereby improving the imaging quality of the optical lens. The second lens can be of a concave-convex surface type, so that light rays in the edge field of view can be gathered, the gathered light rays can smoothly enter the rear-end optical system, and the trend of the light rays is further in stable transition. In addition, the second lens is set to be in a thick meniscus shape with the convex surface facing the image side, so that the influence of the second lens on the field curvature of the optical lens can be reduced, and the imaging quality of the optical lens is improved.

In some embodiments, the third lens element may have a negative refractive power, which is beneficial to balance the spherical aberration caused by the second lens element and improve the imaging quality of the optical lens. The third lens can be of a convex-concave surface type, so that the luminous flux at the rear end of the optical lens can be increased, the shooting effect in a dark environment can be improved, and the imaging quality of the optical lens can be ensured. The third lens can be of a concave-convex surface type or a biconcave surface type, so that light rays in the edge field of view can be converged, the deflection angle of the light rays can be reduced, and the trend of the light rays can be further in stable transition.

In some embodiments, the fourth lens element may have positive refractive power, which is beneficial to suppress the incident angle of the peripheral field of view, and effectively transmit more light beams to the rear end of the optical lens, thereby improving the imaging quality of the optical lens. The fourth lens can be of a double-convex surface type, so that the imaging area of the optical lens can be increased, various aberrations of the optical lens can be balanced, and the imaging quality of the optical lens can be improved.

In some embodiments, the fifth lens element may have a negative focal power, which is beneficial to balance off-axis aberration of the optical lens, and simultaneously, increase an imaging area of the optical lens, and improve imaging quality of the optical lens. The fifth lens can be of a convex-concave surface type, so that marginal field-of-view light can be converged, the imaging area of the optical lens is increased, and the imaging quality of the optical lens is improved.

In some embodiments, the third lens element and the fourth lens element are cemented together to form a cemented lens, which is beneficial to correcting the on-axis aberration of the optical lens and improving the imaging quality of the optical lens.

In some embodiments, a diaphragm for limiting the light beam may be disposed between the second lens and the third lens, which can reduce the occurrence of astigmatism of the optical lens, and is beneficial to converging more light rays into the rear end of the optical lens, increasing the luminous flux at the rear end of the optical lens, and improving the relative illuminance of the optical lens. A diaphragm used for limiting light beams can be arranged between the third lens and the fourth lens, so that the distortion of the optical lens can be reduced, the light rays entering the rear end of the optical lens can be converged, and the caliber of the rear end of the optical lens can be reduced.

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, more incident rays are provided for the optical lens, and therefore enough scene information is obtained.

In some embodiments, the field angle FOV of the optical lens satisfies: the FOV is more than or equal to 210 degrees. The method meets the range, is favorable for realizing the super wide angle characteristic, can acquire more scene information and meets the requirement of large-range detection.

In some embodiments, the incident angle CRA on the image plane of the full-field chief ray of the optical lens satisfies: 30 DEG < CRA < 40 deg. Satisfying the above range, the numerical value of the tolerance between the CRA of the optical lens and the CRA of the chip photosensitive element can be made large, and the illuminance of the edge imaging region can be ensured.

In some embodiments, the field angle FOV and the aperture value FNO of the optical lens satisfy: 120 DEG < FOV/FNO < 150 deg. Satisfying the above range is advantageous for enlarging the field angle of the optical lens and increasing the aperture of the optical lens, and realizes the characteristics of an ultra-wide angle and a large aperture. The realization of the super-wide angle characteristic is favorable for the optical lens to acquire more scene information, the requirement of large-range detection is met, and the realization of the large aperture characteristic is favorable for improving the problem that the relative brightness of the marginal field of view is reduced rapidly caused by the super-wide angle, so that the acquisition of more scene information is also facilitated.

In some embodiments, the total optical length TTL of the optical lens and the real image height IH corresponding to the maximum field angle satisfy: TTL/IH is less than 3.1. Satisfying the above range, taking good image quality into account, being beneficial to shortening the total length of the optical lens and realizing miniaturization design.

In some embodiments, the real image height IH at which the effective focal length f of the optical lens corresponds to the maximum field angle satisfies: IH/f is more than 3.0 and less than 3.5. The ultra-wide angle characteristic can be realized by meeting the range, so that the requirement of large-range shooting is met, the large image surface characteristic can be realized, and the imaging quality of the optical lens is improved.

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 2.5 and less than 3.0. Satisfying above-mentioned scope, being favorable to guaranteeing that optical lens obtains sufficient luminous flux for optical lens obtains promoting at image plane edge luminance and avoids the production of vignetting, can guarantee optical lens's image height simultaneously again and keep at higher level, realized the optical characteristic of big image plane promptly, provide the condition for optical lens arranges with the image sensor of higher pixel, thereby promote optical lens's imaging quality.

In some embodiments, the back focal length BFL and the effective focal length f of the optical lens satisfy: BFL/f is more than 1.1 and less than 1.4. The method meets the range, is favorable for reasonably controlling the back focal length, and ensures the matching performance of the optical lens and the image sensor.

In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -5.0 < f1/f < 0. Satisfying the above range makes it possible to provide the first lens with an appropriate negative refractive power, which is advantageous for enlarging the angle of view of the optical lens and reducing aberrations other than distortion generated by the first lens itself.

In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: f2/f is more than 0 and less than 4.0. The optical lens meets the range, can ensure that the second lens has proper positive focal power, is favorable for correcting various aberrations brought by the first lens, and improves the imaging quality of the optical lens.

In some embodiments, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: -3.0 < f3/f < -1.5. The third lens has appropriate negative focal power, so that spherical aberration caused by the second lens can be balanced, the imaging quality of the optical lens is improved, and the imaging quality of the optical lens is improved.

In some embodiments, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: f4/f is more than 1.2 and less than 1.8. Satisfying above-mentioned scope, can making the fourth lens have appropriate positive focal power, be favorable to suppressing marginal visual field incident angle, transmit more light beams to optical lens rear end effectively, promote optical lens's image quality.

In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -40 < f5/f < 0. The fifth lens has appropriate negative focal power, so that off-axis aberration of the optical lens can be balanced, the imaging area of the optical lens is increased, and the imaging quality of the optical lens is improved.

In some embodiments, the effective focal length f of the optical lens and the first lens object side radius of curvature R1 satisfy: r1/f < 12. The range is met, the field angle of the optical lens is increased, and therefore the requirement of large-range shooting is met.

In some embodiments, the radius of curvature R1 of the object-side surface of the first lens and the radius of curvature R2 of the image-side surface satisfy: 0.5 < (R1-R2)/(R1+ R2) < 0.8. Satisfying the above range is advantageous for obtaining a larger field angle range, which is advantageous for increasing the collection of large field rays into the rear lens as much as possible.

In some embodiments, the radius of curvature R3 of the object-side surface of the second lens and the radius of curvature R4 of the image-side surface satisfy: 0.3 < (R3-R4)/(R3+ R4) < 0.6. The light converging device meets the range, is beneficial to converging light rays of the edge field of view, enables the converged light rays to smoothly enter a rear-end optical system, and further enables the light rays to stably transit.

In some embodiments, the radius of curvature R5 of the object-side surface of the third lens and the radius of curvature R6 of the image-side surface satisfy: i R5/R6I < 3.0. The range is satisfied, and the imaging quality of the optical lens is improved.

In some embodiments, the radius of curvature R7 of the object-side surface of the fourth lens and the radius of curvature R8 of the image-side surface satisfy: i R7/R8I < 1.2. The range is satisfied, the imaging area of the optical lens is increased, various aberrations of the optical lens are balanced, and the imaging quality of the optical lens is improved.

In some embodiments, the radius of curvature R9 of the object-side surface of the fifth lens and the radius of curvature R10 of the image-side surface satisfy: 0 < (R9-R10)/(R9+ R10) < 0.5. The optical lens meets the range, is favorable for converging light rays of the edge field of view, increases the imaging area of the optical lens, and improves the imaging quality of the optical lens.

In some embodiments, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: i f1+ f 2I < 1.0. The optical lens imaging device meets the range, is favorable for balancing the off-axis aberration of the optical lens, and improves the imaging quality 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, F are second-order, fourth-order, sixth-order, eighth-order, tenth-order and twelfth-order curved coefficients, respectively.

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

Example 1

Referring to fig. 1, a schematic structural diagram of an optical lens system 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, an aperture stop ST, a third lens L3, a fourth lens L4, a fifth lens L5, and a filter G1.

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

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

a diaphragm ST;

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

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

the fifth lens element L5 has negative power, and has a convex object-side surface S9 and a concave image-side surface S10;

the third lens L3 and the fourth lens L4 are cemented with each other to constitute a cemented lens;

the object side surface S11 of the filter G1 is a plane, and the image side surface S12 is a plane;

the image forming surface S13 is a plane.

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

TABLE 1-1

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

Tables 1 to 2

In the present embodiment, a curvature of field curve graph, a relative illuminance graph, an MTF graph, an axial aberration graph, and a vertical axis chromatic aberration graph of the optical lens are respectively shown in fig. 2, fig. 3, fig. 4, fig. 5, and fig. 6.

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 +/-0.08 mm, which indicates that the field curvature of the optical lens is better corrected.

Fig. 3 shows a relative illuminance curve of example 1, 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 is still greater than 55% at the maximum half field angle, which indicates that the relative illuminance of the optical lens is high.

Fig. 4 shows MTF (modulation transfer function) graphs of embodiment 1, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.5 in the whole field of view, and in the range of 0-120 lp/mm, the MTF curve is uniformly and smoothly reduced in the process from the center to the edge field of view, and the MTF has good imaging quality and good detail resolution capability under the conditions of low frequency and high frequency.

Fig. 5 shows an axial aberration curve of example 1, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: mm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the offset of the axial aberration is controlled within ± 0.05mm, which indicates that the optical lens can effectively correct the axial aberration.

Fig. 6 shows a vertical axis chromatic aberration curve of example 1, which shows chromatic aberration at different image heights on an image forming plane for each wavelength with respect to a center wavelength (0.55 μm), the horizontal axis shows a vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis shows a normalized angle of view. As can be seen from the figure, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within +/-4 mu m, which shows that the optical lens can effectively correct the chromatic aberration of the marginal field of view and the secondary spectrum of the whole image plane.

Example 2

Referring to fig. 7, a schematic structural diagram of an optical lens system according to embodiment 2 of the present invention is shown, the optical lens system sequentially includes, from an object side to an image plane along an optical axis: a first lens L1, a second lens L2, a third lens L3, a stop ST, a fourth lens L4, a fifth lens L5, and a filter G1.

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

a diaphragm ST;

the fifth lens element L5 has negative power, and has a convex object-side surface S9 and a concave image-side surface S10.

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

TABLE 2-1

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

Tables 2 to 2

In the present embodiment, a curvature of field curve graph, a relative illuminance graph, an MTF graph, an axial aberration graph, and a vertical axis chromatic aberration graph of the optical lens are respectively shown in fig. 8, 9, 10, 11, and 12.

Fig. 8 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 +/-0.08 mm, which indicates that the field curvature of the optical lens is better corrected.

Fig. 9 shows a relative illuminance curve of example 2, 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 50% at the maximum half field angle, which indicates that the relative illuminance of the optical lens is high.

Fig. 10 shows MTF (modulation transfer function) graphs of embodiment 2, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.5 in the whole field of view, and in the range of 0-120 lp/mm, the MTF curve is uniformly and smoothly reduced in the process from the center to the edge field of view, and the MTF has good imaging quality and good detail resolution capability under the conditions of low frequency and high frequency.

Fig. 11 shows an axial aberration curve of example 2, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: mm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the offset of the axial aberration is controlled within ± 0.03mm, which indicates that the optical lens can effectively correct the axial aberration.

Fig. 12 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 +/-4 mu m, which shows that the optical lens can effectively correct the chromatic aberration of the marginal field of view and the secondary spectrum of the whole image plane.

Example 3

Referring to fig. 13, a schematic structural diagram of an optical lens system according to embodiment 3 of the present invention is shown, the optical lens system sequentially includes, from an object side to an image plane along an optical axis: a first lens L1, a second lens L2, a third lens L3, a stop ST, a fourth lens L4, a fifth lens L5, and a filter G1.

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

a diaphragm ST;

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

TABLE 3-1

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

TABLE 3-2

In the present embodiment, a curvature of field curve graph, a relative illuminance graph, an MTF graph, an axial aberration graph, and a vertical axis chromatic aberration graph of the optical lens are respectively shown in fig. 14, 15, 16, 17, and 18.

Fig. 14 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 +/-0.05 mm, which indicates that the field curvature of the optical lens is better corrected.

Fig. 15 shows a relative illuminance curve of example 3, which represents relative illuminance values at different angles of field of view on the imaging plane, with the horizontal axis representing the half field angle (unit: °) and the vertical axis representing the relative illuminance (unit:%). As can be seen from the figure, the relative illuminance value of the optical lens is still greater than 50% at the maximum half field angle, which indicates that the relative illuminance of the optical lens is high.

Fig. 16 shows MTF (modulation transfer function) graphs of embodiment 3, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.5 in the whole field of view, and in the range of 0-90 lp/mm, the MTF curve is uniformly and smoothly reduced in the process from the center to the edge field of view, and the MTF has good imaging quality and good detail resolution capability under the conditions of low frequency and high frequency.

Fig. 17 shows an axial aberration curve of example 3, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: mm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the offset of the axial aberration is controlled within ± 0.05mm, which indicates that the optical lens can effectively correct the axial aberration.

Fig. 18 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 +/-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.

Please refer to table 4, which shows the optical characteristics corresponding to the above embodiments, including the effective focal length f, the total optical length TTL, the aperture FNO, the real image height IH, and the field angle FOV of the optical lens, and the values corresponding to each conditional expression in the embodiments.

TABLE 4

In summary, the optical lens of the embodiments of the invention realizes the advantages of large field angle, large aperture and high resolution by reasonably matching the lens shape and focal power combination among the lenses.

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

Claims

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

the first lens with negative focal power has a convex object-side surface and a concave image-side surface;

the second lens with positive focal power has a concave object-side surface and a convex image-side surface;

a third lens having a negative optical power;

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

a fifth lens element with negative refractive power having a convex object-side surface and a concave image-side surface;

2. An optical lens according to claim 1, wherein the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: i f1+ f 2I < 1.0.

3. The optical lens according to claim 1, wherein a real image height IH of the optical lens corresponding to an effective focal length f and a maximum field angle satisfies: IH/f is more than 3.0 and less than 3.5.

4. The optical lens of claim 1, wherein a real image height IH corresponding to a maximum field angle and a total optical length TTL of the optical lens satisfy: TTL/IH is less than 3.1.

5. An optical lens according to claim 1, wherein the incidence angle CRA on the image plane of the full-field chief ray of the optical lens satisfies: 30 DEG < CRA < 40 deg.

6. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -5.0 < f1/f < 0.

7. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: f2/f is more than 0 and less than 4.0.

8. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: -3.0 < f3/f < -1.5.

9. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: f4/f is more than 1.2 and less than 1.8.

10. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -40 < f5/f < 0.