CN117270171A

CN117270171A - Optical lens

Info

Publication number: CN117270171A
Application number: CN202311261128.9A
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: 2023-09-27
Filing date: 2023-09-27
Publication date: 2023-12-22

Abstract

The invention provides an optical lens, which comprises eight lenses in sequence 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 second lens having negative optical power, the image side surface of which is concave; a third lens having positive optical power, both the object-side surface and the image-side surface of which are convex; a fourth lens element with positive refractive power having convex object-side and image-side surfaces; a fifth lens element with positive refractive power having convex object-side and image-side surfaces; a sixth lens element with negative refractive power having concave object-side and image-side surfaces; a seventh lens element with negative refractive power having a convex object-side surface and a concave image-side surface; the eighth lens element with positive refractive power has a convex object-side surface and a concave image-side surface. The optical lens provided by the invention improves the imaging quality of the optical lens, reduces the aberration and improves the imaging quality of the optical lens through reasonable configuration of the surface types of the lenses and reasonable collocation of the focal power.

Description

Optical lens

Technical Field

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

Background

With the continuous progress of the existing image processing algorithm and AI technology, the fisheye lens is used as a special lens in the optical lens, and is widely applied to various fields such as a moving camera, an unmanned aerial vehicle, an intelligent doorbell, an intelligent home and the like, so that the requirements on the fisheye lens are higher and higher.

However, the existing fisheye lens device has a plurality of defects, such as too long size, large volume, heavy weight and inconvenient carrying; the increase of the angle of view of the lens causes difficulty in correcting the system aberration and degradation of imaging quality; the relative aperture of the lens is smaller, the light transmission performance is poor, and the lens cannot adapt to darker environments; and the existing lens imaging target surface is smaller, so that the market demand is difficult to meet.

Therefore, there is a need to develop an optical lens having one or more advantages of a large angle of view, high imaging quality, large aperture, small size, large target surface, etc., so as to better satisfy the high demands of the market for fisheye lenses.

Disclosure of Invention

In view of the foregoing, an object of the present invention is to provide an optical lens having an advantage of excellent imaging quality.

The invention provides an optical lens, which comprises eight lenses in sequence 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 second lens having negative optical power, the image side surface of which is concave;

a third lens having positive optical power, both the object-side surface and the image-side surface of which are convex;

a fourth lens element with positive refractive power having convex object-side and image-side surfaces;

a fifth lens element with positive refractive power having convex object-side and image-side surfaces;

a sixth lens element with negative refractive power having concave object-side and image-side surfaces;

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

an eighth lens element with positive refractive power having a convex object-side surface and a concave image-side surface;

focal length f of the seventh lens ₇ The effective focal length f of the lens meets the following conditions: f (f) ₇ /f<-5.0。

Further preferably, a reflecting element is disposed between the third lens and the fourth lens, a surface of the reflecting element facing the object side is an incident surface, and a surface facing the imaging surface is an exit surface.

Further preferably, the reflecting element is a prism, and the incident surface and the emergent surface of the prism are both planes.

Further preferably, a protective lens is disposed between the first lens and the object side, the object side of the protective lens is a convex surface, and the image side is a concave surface.

Further preferably, the seventh lens has an object-side surface radius of curvature R ₁₃ And an image side radius of curvature R ₁₄ The method meets the following conditions: (R) ₁₃ +R ₁₄ )/(R ₁₃ -R ₁₄₎ >1.8。

Further preferably, the distance CT between the third lens and the fourth lens on the optical axis ₃₄ The effective focal length f of the lens meets the following conditions: 4.0<CT ₃₄ /f<5.5。

Further preferably, the maximum field angle FOV of the optical lens satisfies: FOV >190 °.

Further preferably, the optical total length TTL and the effective focal length f of the optical lens satisfy: 17.0< TTL/f <20.0.

Further preferably, the effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle satisfy: 3.0< IH/f <4.0.

Further preferably, the focal length f of the first lens ₁ The effective focal length f of the lens meets the following conditions: -5.0<f ₁ /f<-3.0。

Further preferably, the focal length f of the second lens ₂ The effective focal length f of the lens meets the following conditions: -5.0<f ₂ /f<-3.0。

The optical lens provided by the invention improves the imaging quality of the optical lens, reduces the aberration and improves the imaging quality of the optical lens through reasonable configuration of the surface types of the lenses and reasonable collocation of the focal power.

Drawings

The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:

fig. 1 and fig. 2 are schematic diagrams of an unprotected lens and a protected lens of an optical lens in embodiment 1 of the present invention, respectively.

Fig. 3 is a graph showing a field curvature of an optical lens in embodiment 1 of the present invention.

Fig. 4 is an F-Theta distortion curve of the optical lens in example 1 of the present invention.

Fig. 5 is a graph showing the relative illuminance of the optical lens in embodiment 1 of the present invention.

Fig. 6 is an MTF graph of the optical lens in example 1 of the present invention.

Fig. 7 is an axial aberration diagram of the optical lens in embodiment 1 of the present invention.

Fig. 8 is a graph showing a vertical axis chromatic aberration of an optical lens in embodiment 1 of the present invention.

Fig. 9 and 10 are schematic diagrams of an unprotected lens and a protected lens of an optical lens in embodiment 2 of the present invention, respectively.

Fig. 11 is a graph showing a field curvature of an optical lens in embodiment 2 of the present invention.

Fig. 12 is an F-Theta distortion curve of the optical lens in embodiment 2 of the present invention.

Fig. 13 is a graph showing the relative illuminance of the optical lens in embodiment 2 of the present invention.

Fig. 14 is an MTF graph of the optical lens in example 2 of the present invention.

Fig. 15 is an axial aberration diagram of the optical lens in embodiment 2 of the present invention.

Fig. 16 is a vertical axis chromatic aberration chart of the optical lens in embodiment 2 of the present invention.

Fig. 17 and 18 are schematic diagrams of the structures of an unprotected lens and a protected lens of an optical lens in embodiment 3 of the present invention, respectively.

Fig. 19 is a graph showing the field curvature of the optical lens in embodiment 3 of the present invention.

FIG. 20 is a graph showing F-Theta distortion of an optical lens in example 3 of the present invention.

Fig. 21 is a graph showing the relative illuminance of the optical lens in embodiment 3 of the present invention.

Fig. 22 is an MTF graph of the optical lens in example 3 of the present invention.

Fig. 23 is an axial aberration diagram of an optical lens in embodiment 3 of the present invention.

Fig. 24 is a graph showing a vertical axis chromatic aberration of an optical lens in embodiment 3 of the present invention.

Fig. 25 and 26 are schematic diagrams showing the structure of an unprotected lens and a protected lens of an optical lens in embodiment 4 of the present invention, respectively.

Fig. 27 is a graph showing the field curvature of an optical lens in embodiment 4 of the present invention.

FIG. 28 is a graph showing F-Theta distortion of an optical lens in example 4 of the present invention.

Fig. 29 is a graph showing the relative illuminance of the optical lens in embodiment 4 of the present invention.

Fig. 30 is an MTF graph of the optical lens in example 4 of the present invention.

Fig. 31 is an axial aberration diagram of the optical lens in embodiment 4 of the present invention.

Fig. 32 is a vertical axis chromatic aberration chart of the optical lens in embodiment 4 of the invention.

The invention will be further described in the following detailed description 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 these detailed descriptions are merely illustrative of embodiments of the present application and are not intended to limit the scope of the present 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 the present specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the feature. Accordingly, a first lens discussed below may also be referred to as a second lens or a third lens without departing from the teachings of the present invention.

In the drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for convenience of explanation. In particular, the spherical or aspherical shape shown in the drawings is shown by way of example. That is, the shape of the spherical or aspherical surface is not limited to the shape of the spherical or aspherical surface shown in the drawings. The figures are merely examples and are 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, then 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 referred to as the object side of the lens, and the surface of each lens closest to the imaging plane is referred to as the image side of the lens.

It will be further understood that the terms "comprises," "comprising," "includes," "including," "having," "containing," 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. Furthermore, when a statement such as "at least one of the following" appears after a list of features that are listed, the entire listed feature is modified instead of modifying a separate element in the list. Furthermore, when describing embodiments of the present application, use of "may" means "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, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

The optical lens of the embodiment of the invention sequentially comprises from an object side to an imaging surface along an optical axis: the optical lens comprises a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens, a seventh lens, an eighth lens and an optical filter.

In some embodiments, the first lens may have negative optical power, which facilitates reducing the tilt angle of incident light rays, thereby achieving effective sharing of the large field of view of the object. The object side surface of the first lens is a convex surface, and the image side surface is a concave surface; the method is favorable for collecting the light rays of the edge view field as far as possible to enter the rear optical lens, and large-angle light ray collection is realized.

In some embodiments, the second lens may have negative focal power, which is helpful for smooth transition of light, enlarging the field angle of the optical imaging lens, reducing the difficulty of correcting distortion and chromatic aberration of the rear lens, and improving the image quality of the optical imaging lens. The second lens is concave on the image side surface, which is beneficial to increasing the angle of view of the optical lens and improving the imaging quality of the optical lens.

In some embodiments, the third lens may have positive optical power, which may be advantageous for improving the light converging power of the optical lens. The object side surface and the image side surface of the third lens are convex, so that various aberrations generated by the optical lens can be balanced, and the imaging quality of the optical lens can be improved.

In some embodiments, the fourth lens may have positive optical power, with both the object-side and image-side surfaces being convex; the optical lens is beneficial to improving the light converging capability of the optical lens, and meanwhile, the aberration of the optical lens can be balanced, and the imaging quality of the optical lens is improved.

In some embodiments, the fifth lens element may have positive optical power, with both the object-side and image-side surfaces being convex; the optical lens is beneficial to improving the light converging capability of the optical lens, and meanwhile, the aberration of the optical lens can be balanced, and the imaging quality of the optical lens is improved.

In some embodiments, the sixth lens may have negative optical power, with both the object-side and image-side surfaces being concave; the method is beneficial to increasing the field angle of the optical lens and improving the imaging quality of the optical lens.

In some embodiments, the seventh lens element with negative refractive power has a convex object-side surface and a concave image-side surface; the method is beneficial to increasing the field angle of the optical lens and improving the imaging quality of the optical lens.

In some embodiments, the eighth lens element may have positive refractive power, wherein the object-side surface thereof is convex and the image-side surface thereof is concave; the angle of incidence of the edge view field on the imaging surface is favorably pressed, more light beams are effectively transmitted to the imaging surface, meanwhile, the aberration of the optical lens can be balanced, and the imaging quality of the optical lens is improved.

In some embodiments, in order to reduce the size of the optical lens, a reflective element for optical path folding without optical power may be disposed between the third lens and the fourth lens, and the reflective element is a prism. The surface of the prism facing the object side is an incident surface, the surface facing the imaging surface is an emergent surface, and the incident surface and the emergent surface are planes. The prism can adopt a right-angle prism, and light rays from the object side direction enter the prism from the incident surface, are reflected by the reflecting surface and then are emitted from the emergent surface. The thickness of the lens can be effectively shortened by setting the bending light path of the prism.

In some embodiments, to protect the first lens in contact with the exterior, a protective lens with optical power is disposed between the first lens and the object side, the protective lens having a convex object side and a concave image side. Through setting up the protection lens, play the effect of protection optical lens, can improve the anti-impact of optical lens, scratch resistance ability, little influence to optical lens imaging quality simultaneously.

In some embodiments, the focal length f of the seventh lens ₇ The effective focal length f with the optical lens satisfies: f (f) ₇ /f<-5.0. The range is satisfied, so that the seventh lens has negative focal power, which is beneficial to increasing the angle of view of the optical lens and improving the imaging quality of the optical lens.

In some embodiments, the seventh lens has an object-side radius of curvature R ₁₃ And an image side radius of curvature R ₁₄ The method meets the following conditions: (R) ₁₃ +R ₁₄ )/(R ₁₃ -R ₁₄₎ >1.8. Satisfying the above range, the image height can be increased by controlling the fringe field beam profile while reducing the off-axis aberration of the optical lens.

In some embodiments, the distance CT between the third lens and the fourth lens on the optical axis ₃₄ An effective focal length f of the lens is as follows：4.0<CT ₃₄ /f<5.5. The range is satisfied, the realization of the foldback structure of the optical lens is facilitated, and the thickness of the lens is reduced.

In some embodiments, the maximum field angle FOV of the optical lens satisfies: FOV >190 °. Satisfying the above range, the optical lens can be realized to have a large angle of view.

In some embodiments, the optical total length TTL and the effective focal length f of the optical lens satisfy: 17.0< TTL/f <20.0. The range is satisfied, enough space is ensured to adjust the lens structure, and the imaging effect is optimized.

In some embodiments, the effective focal length f of the optical lens and the radian θ of the maximum half field angle and the real image height IH corresponding to the maximum field angle satisfy: 0.8< (IH/2)/(fXθ) <1.1. The above range is satisfied, and the distortion is controlled in a proper range, which is favorable for increasing the true image height.

In some embodiments, the effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle satisfy: 3.0< IH/f <4.0. The range is satisfied, the large image surface characteristic can be realized, and the imaging quality of the optical lens is improved.

In some embodiments, the focal length f of the first lens ₁ The effective focal length f with the optical lens satisfies: -5.0<f ₁ /f<-3.0. The range is satisfied, the first lens can have proper negative focal power, the negative focal power is prevented from being too concentrated, the field angle is increased, the marginal field light rays are collected as much as possible and enter the rear optical lens, and the large-angle light ray collection is realized.

In some embodiments, the focal length f of the second lens ₂ The effective focal length f with the optical lens satisfies: -5.0<f ₂ /f<-3.0. The range is satisfied, so that the second lens has proper negative focal power, the angle of view is increased, and the imaging quality of the optical lens is improved.

In some embodiments, the focal length f of the third lens ₃ The effective focal length f with the optical lens satisfies: 4.0<f ₃ /f<7.0. The third lens has proper positive focal power, which is beneficial to improving the light collection of the optical lensThe focusing capability can balance various aberrations generated by the optical lens and improve the imaging quality of the optical lens.

In some embodiments, the effective focal length f of the optical lens and the focal length f of the fourth lens ₄ The method meets the following conditions: 3.0<f ₄ /f<4.0. The range is satisfied, so that the fourth lens has proper positive focal power, the light converging capability of the optical lens is improved, meanwhile, the aberration of the optical 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 The method meets the following conditions: 2.0<f ₅ /f<3.0. The range is satisfied, so that the fifth lens has proper positive focal power, the light converging capability of the optical lens is improved, meanwhile, the aberration of the optical 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 sixth lens ₆ The method meets the following conditions: -2.5<f ₆ /f<-1.5. The range is satisfied, so that the sixth lens has proper negative focal power, which is beneficial to increasing the angle of view 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 eighth lens ₈ The method meets the following conditions: 5.0<f ₈ /f<9.0. The range is satisfied, the eighth lens has proper positive focal power, is favorable for pressing the angle of incidence of the marginal view field on the imaging surface, effectively transmits more light beams to the imaging surface, can balance the aberration of the optical lens, and improves the imaging quality of the optical lens.

In some embodiments, the focal length f of the first lens of the optical lens ₁ Focal length f of the second lens ₂ The method meets the following conditions: 0.9<f ₁ /f ₂ <1.1. The optical lens has the advantages that the range is met, the first lens and the second lens can have proper negative focal power, smooth transition of light is facilitated, the angle of view of the optical lens is enlarged, the difficulty in correcting distortion and chromatic aberration of the rear-end lens is reduced, and the imaging quality of the optical lens is improved.

In some embodiments, the sixth lens and the seventh lens can be glued to form a glued lens, so that chromatic aberration of the optical lens can be effectively corrected, decentered sensitivity of the optical lens can be reduced, aberration of the optical lens can be balanced, and imaging quality of the optical lens can be improved; the assembly sensitivity of the optical lens can be reduced, the processing technology difficulty of the optical lens is further reduced, and the assembly yield of the optical lens is improved.

For better optical performance of the system, a plurality of aspheric lenses are adopted in the lens, and the shape of each aspheric surface of the optical lens meets the following equation:

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

The invention is further illustrated in the following examples. In various embodiments, the thickness, radius of curvature, and material selection portion of each lens in the optical lens may vary, and for specific differences, reference may be made to the parameter tables of the various embodiments. The following examples are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following examples, and any other changes, substitutions, combinations or simplifications that do not depart from the gist of the present invention are intended to be equivalent substitutes within the scope of the present invention.

Example 1

Referring to fig. 1, a schematic structural diagram of an optical lens provided in embodiment 1 of the present invention is shown, where the optical lens includes, in order from an object side to an imaging plane along an optical axis: the optical lens assembly includes a first lens L1, a second lens L2, a third lens L3, a prism G1, a fourth lens L4, a stop ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and an optical filter G2.

The first lens element L1 has negative refractive power, wherein an object-side surface S1 thereof is convex, and an image-side surface S2 thereof is concave;

the second lens element L2 has negative refractive power, wherein an object-side surface S3 thereof is convex, and an image-side surface S4 thereof is concave;

the third lens element L3 has positive refractive power, and both an object-side surface S5 and an image-side surface S6 thereof are convex;

the surface of the prism G1 facing the object side is an incident surface, the surface facing the imaging surface is an emergent surface, and the incident surface and the emergent surface are planes;

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

a diaphragm ST;

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

the sixth lens element L6 has negative refractive power, and both the object-side surface S11 and the image-side surface S12 thereof are concave;

the seventh lens element L7 with negative focal power has a convex object-side surface S12 and a concave image-side surface S13;

the sixth lens element L6 and the seventh lens element L7 form a cemented lens assembly, i.e., the cemented surface between the image side surface of the sixth lens element L6 and the object side surface of the seventh lens element L7 is S12;

the eighth lens element L8 with positive refractive power has a convex object-side surface S14 and a concave image-side surface S15;

the object side surface S16 and the image side surface S17 of the optical filter G2 are planes;

the imaging surface S18 is a plane.

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

TABLE 1-1

The surface profile parameters of the aspherical lens of the optical lens in example 1 are shown in tables 1 to 2.

TABLE 1-2

Referring to fig. 2, in this embodiment, in order to protect the optical lens, a detachable protection lens may be added between the first lens element L1 and the object side, the protection lens has a negative optical power, the object side S19 is a convex surface, and the image side S20 is a concave surface. The relevant parameters are shown in tables 1-3.

Tables 1 to 3

In this embodiment, the field curvature curve, the F-Theta distortion curve, the relative illuminance curve, the MTF curve, the axial aberration curve, and the vertical chromatic aberration curve of the optical lens are shown in fig. 3, 4, 5, 6, 7, and 8, respectively.

Fig. 3 shows a field 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, the horizontal axis indicates the amount of shift (unit: mm), and the vertical axis indicates the half angle of view (unit: °). From the graph, the field curvature of the meridian image plane and the sagittal image plane is controlled within-0.03-0.01 mm, which indicates that the optical lens can well correct the field curvature.

Fig. 4 shows the F-Theta distortion curve of example 1, which represents F-Theta distortion of light rays of different wavelengths at different image heights on an imaging plane, the horizontal axis represents the F-Theta distortion value (unit:%) and the vertical axis represents the half field angle (unit: °). From the graph, the F-Theta distortion of the optical lens is controlled within-12% -0, the image compression of the edge angle area is gentle, and the definition of the unfolded image is effectively improved.

Fig. 5 shows the relative illuminance curve of example 1, which represents the relative illuminance values for different field angles on the imaging plane, the horizontal axis represents the half field angle (in: °), and the vertical axis represents the relative illuminance (in:%). As can be seen from the figure, the relative illuminance 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 illuminance.

Fig. 6 shows an MTF (modulation transfer function) graph of example 1, which represents the lens imaging modulation degree of different spatial frequencies at each view field, the horizontal axis represents the spatial frequency (unit: lp/mm), and the vertical axis represents the MTF value. As can be seen from the graph, the MTF values of the embodiment are 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 of the field of view from the center to the edge, and the MTF image has better imaging quality and better detail resolution under the conditions of low frequency and high frequency.

Fig. 7 shows an axial aberration diagram of example 1, which represents aberration of each wavelength on the optical axis at the imaging plane, the horizontal axis represents an axial aberration value (unit: μm), and the vertical axis represents a normalized pupil radius. As can be seen from the figure, the offset of the axial aberration is controlled within-10 mu m to 10 mu m, which indicates that the optical lens can better correct the axial aberration.

Fig. 8 shows a vertical axis color difference graph of example 1, which shows color differences at different image heights on an imaging plane for each wavelength with respect to a center wavelength (0.55 μm), with the horizontal axis showing a vertical axis color difference value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis showing a normalized field angle. As can be seen from the graph, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within-1 mu m to 1 mu m, which shows that the optical lens can excellently correct chromatic aberration of an edge view field and a secondary spectrum of the whole image surface.

Example 2

Referring to fig. 9, a schematic structural diagram of an optical lens provided in embodiment 2 of the present invention is shown, and the present embodiment is mainly characterized in that the optical parameters such as the radius of curvature and the thickness of the lens are different from those of embodiment 1.

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

TABLE 2-1

The surface profile parameters of the aspherical lens of the optical lens in example 2 are shown in tables 2-2.

TABLE 2-2

Referring to fig. 10, in this embodiment, in order to protect the optical lens, a detachable protection lens may be added between the first lens element L1 and the object side, the protection lens has a negative optical power, the object side S19 is a convex surface, and the image side S20 is a concave surface. The relevant parameters are shown in tables 2-3.

Tables 2 to 3

In this embodiment, the field curvature curve, the F-Theta distortion curve, the relative illuminance curve, the MTF curve, the axial aberration curve, and the vertical chromatic aberration curve of the optical lens are shown in fig. 11, 12, 13, 14, 15, and 16, respectively.

Fig. 11 shows a field 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, the horizontal axis shows the amount of shift (unit: mm), and the vertical axis shows the half angle of view (unit: °). From the graph, the field curvature of the meridian image plane and the sagittal image plane is controlled within-0.02-0.01 mm, which indicates that the optical lens can well correct the field curvature.

Fig. 12 shows an F-Theta distortion curve of example 2, which represents F-Theta distortion of light rays of different wavelengths at different image heights on an imaging plane, with the horizontal axis representing F-Theta distortion values (in:%) and the vertical axis representing half field angles (in: °). From the figure, the F-Theta distortion of the optical lens is controlled within 0-6%, the image compression of the edge angle area is gentle, and the definition of the unfolded image is effectively improved.

Fig. 13 shows the relative illuminance curve of example 2, which represents the relative illuminance values for different field angles on the imaging plane, the horizontal axis represents the half field angle (in: °), and the vertical axis represents the relative illuminance (in:%). As can be seen from the figure, the relative illuminance value of the optical lens is still greater than 40% at the maximum half field angle, which indicates that the optical lens has better relative illuminance.

Fig. 14 shows an MTF (modulation transfer function) graph of example 2, which represents the lens imaging modulation degree of different spatial frequencies at each view field, the horizontal axis represents the spatial frequency (unit: lp/mm), and the vertical axis represents the MTF value. As can be seen from the graph, the MTF values of the embodiment are 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 of the field of view from the center to the edge, and the MTF image has better imaging quality and better detail resolution under the conditions of low frequency and high frequency.

Fig. 15 shows an axial aberration diagram of example 2, which represents aberration of each wavelength on the optical axis at the imaging plane, the horizontal axis represents an axial aberration value (unit: μm), and the vertical axis represents a normalized pupil radius. As can be seen from the graph, the offset of the axial aberration is controlled within-10 mu m to 15 mu m, which indicates that the optical lens can better correct the axial aberration.

Fig. 16 shows a vertical axis color difference graph of example 2, which shows color differences at different image heights on an imaging plane for each wavelength with respect to a center wavelength (0.55 μm), with the horizontal axis showing a vertical axis color difference value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis showing a normalized field angle. As can be seen from the graph, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within-1 mu m to 1 mu m, which shows that the optical lens can excellently correct chromatic aberration of an edge view field and a secondary spectrum of the whole image surface.

Example 3

Referring to fig. 17, a schematic structural diagram of an optical lens provided in embodiment 3 of the present invention is shown, where the optical lens includes, in order from an object side to an imaging plane along an optical axis: the optical lens assembly includes a first lens L1, a second lens L2, a third lens L3, a prism G1, a fourth lens L4, a stop ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and an optical filter G2.

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

a diaphragm ST;

the imaging surface S18 is a plane.

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

TABLE 3-1

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

TABLE 3-2

Referring to fig. 18, in this embodiment, in order to protect the optical lens, a detachable protection lens may be added between the first lens element L1 and the object side, the protection lens has positive optical power, the object side S19 is convex, and the image side S20 is concave. The relevant parameters are shown in tables 3-3.

TABLE 3-3

In this embodiment, the field curvature curve, the F-Theta distortion curve, the relative illuminance curve, the MTF curve, the axial aberration curve, and the vertical chromatic aberration curve of the optical lens are shown in fig. 19, 20, 21, 22, 23, and 24, respectively.

Fig. 19 shows a field 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, the horizontal axis shows the amount of shift (unit: mm), and the vertical axis shows the half angle of view (unit: °). From the graph, the field curvature of the meridian image plane and the sagittal image plane is controlled within-0.05-0.02 mm, which indicates that the optical lens can well correct the field curvature.

Fig. 20 shows an F-Theta distortion curve of example 3, which represents F-Theta distortion at different image heights on an imaging plane for light rays of different wavelengths, with the horizontal axis representing F-Theta distortion values (in:%) and the vertical axis representing half field angles (in: °). From the figure, the F-Theta distortion of the optical lens is controlled within 0-8%, the image compression of the edge angle area is gentle, and the definition of the unfolded image is effectively improved.

Fig. 21 shows the relative illuminance curve of example 3, which represents the relative illuminance values for different field angles on the imaging plane, the horizontal axis represents the half field angle (in: °), and the vertical axis represents the relative illuminance (in:%). As can be seen from the figure, the relative illuminance value of the optical lens is still greater than 40% at the maximum half field angle, which indicates that the optical lens has better relative illuminance.

Fig. 22 shows an MTF (modulation transfer function) graph of example 3, which represents the lens imaging modulation degree of different spatial frequencies at each view field, the horizontal axis represents the spatial frequency (unit: lp/mm), and the vertical axis represents the MTF value. As can be seen from the graph, the MTF values of the embodiment are 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 of the field of view from the center to the edge, and the MTF image has better imaging quality and better detail resolution under the conditions of low frequency and high frequency.

Fig. 23 shows an axial aberration diagram of example 3, which represents aberration of each wavelength on the optical axis at the imaging plane, the horizontal axis represents an axial aberration value (unit: μm), and the vertical axis represents a normalized pupil radius. As can be seen from the graph, the offset of the axial aberration is controlled within-20 mu m to 15 mu m, which indicates that the optical lens can better correct the axial aberration.

Fig. 24 shows a vertical axis color difference graph of example 3, which shows color differences at different image heights on an imaging plane for each wavelength with respect to a center wavelength (0.55 μm), with the horizontal axis showing a vertical axis color difference value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis showing a normalized field angle. As can be seen from the graph, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within-3 mu m to 1 mu m, which shows that the optical lens can excellently correct chromatic aberration of an edge view field and a secondary spectrum of the whole image surface.

Example 4

Referring to fig. 25, a schematic diagram of an optical lens provided in embodiment 4 of the present invention is shown, and the present invention is mainly characterized in that the optical parameters such as the radius of curvature and the thickness of the lens are different from those of embodiment 3.

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

TABLE 4-1

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

TABLE 4-2

Referring to fig. 26, in this embodiment, in order to protect the optical lens, a detachable protection lens may be added between the first lens element L1 and the object side, the protection lens has positive optical power, the object side S19 is convex, and the image side S20 is concave. The relevant parameters are shown in tables 4-3.

TABLE 4-3

In this embodiment, the field curvature curve, the F-Theta distortion curve, the relative illuminance curve, the MTF curve, the axial aberration curve, and the vertical chromatic aberration curve of the optical lens are shown in fig. 27, 28, 29, 30, 31, and 32, respectively.

Fig. 27 shows a field curvature curve of example 4, in which the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane is shown, the horizontal axis represents the amount of shift (unit: mm), and the vertical axis represents the half angle of view (unit: °). From the graph, the field curvature of the meridian image plane and the sagittal image plane is controlled within-0.05-0.02 mm, which indicates that the optical lens can well correct the field curvature.

Fig. 28 shows an F-Theta distortion curve of example 4, which represents F-Theta distortion at different image heights on an imaging plane for light rays of different wavelengths, with the horizontal axis representing F-Theta distortion values (in:%) and the vertical axis representing half field angles (in: °). From the figure, the F-Theta distortion of the optical lens is controlled within 0-3%, the image compression of the edge angle area is gentle, and the definition of the unfolded image is effectively improved.

Fig. 29 shows the relative illuminance curve of example 4, which represents the relative illuminance values for different field angles on the imaging plane, the horizontal axis represents the half field angle (unit: °), and the vertical axis represents the relative illuminance (unit:%). As can be seen from the figure, the relative illuminance value of the optical lens is still greater than 40% at the maximum half field angle, which indicates that the optical lens has better relative illuminance.

Fig. 30 shows an MTF (modulation transfer function) graph of example 4, which represents the lens imaging modulation degree of different spatial frequencies at each view field, the horizontal axis represents the spatial frequency (unit: lp/mm), and the vertical axis represents the MTF value. As can be seen from the graph, the MTF values of the embodiment are 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 of the field of view from the center to the edge, and the MTF image has better imaging quality and better detail resolution under the conditions of low frequency and high frequency.

Fig. 31 shows an axial aberration diagram of example 4, which represents aberration of each wavelength on the optical axis at the imaging plane, the horizontal axis represents an axial aberration value (unit: μm), and the vertical axis represents a normalized pupil radius. As can be seen from the graph, the offset of the axial aberration is controlled within-20 mu m to 10 mu m, which indicates that the optical lens can better correct the axial aberration.

Fig. 32 shows a vertical axis color difference graph of example 4, which shows color differences at different image heights on an imaging plane for each wavelength with respect to a center wavelength (0.55 μm), with the horizontal axis showing a vertical axis color difference value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis showing a normalized field angle. As can be seen from the graph, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within-2 mu m to 1 mu m, which shows that the optical lens can excellently correct chromatic aberration of an edge view field and a secondary spectrum of the whole image surface.

Referring to table 5, the optical characteristics corresponding to the above embodiments include the effective focal length f, the total optical length TTL, the aperture value FNO, the real image height IH, the maximum field angle FOV and the numerical value corresponding to each conditional expression in the embodiments.

TABLE 5

In summary, the optical lens provided by the invention improves the imaging quality of the optical lens, reduces the aberration and improves the imaging quality of the optical lens through reasonable configuration of the surface types of the lenses and reasonable collocation of the focal power.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., 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 present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. 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 foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims

1. An optical lens comprising eight lenses in total, in order from an object side to an imaging plane along an optical axis:

the saidFocal length f of seventh lens ₇ The effective focal length f of the lens meets the following conditions: f (f) ₇ /f<-5.0。

2. The optical lens as claimed in claim 1, wherein a reflecting element is disposed between the third lens and the fourth lens, and a surface of the reflecting element facing the object side is an incident surface and a surface facing the imaging surface is an exit surface.

3. The optical lens as claimed in claim 1, wherein a protective lens is disposed between the first lens element and the object side, the protective lens having a convex object side and a concave image side.

4. The optical lens of claim 1, wherein the seventh lens has an object-side radius of curvature R ₁₃ And an image side radius of curvature R ₁₄ The method meets the following conditions: (R) ₁₃ +R ₁₄ )/(R ₁₃ -R ₁₄₎ >1.8。

5. The optical lens as claimed in claim 1, wherein a distance CT on an optical axis between the third lens and the fourth lens ₃₄ The effective focal length f of the lens meets the following conditions: 4.0<CT ₃₄ /f<5.5。

6. The optical lens of claim 1, wherein a maximum field angle FOV of the optical lens satisfies: FOV >190 °.

7. The optical lens of claim 1, wherein the optical total length TTL and the effective focal length f of the optical lens satisfy: 17.0< TTL/f <20.0.

8. The optical lens according to claim 1, wherein the effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle satisfy: 3.0< IH/f <4.0.

9. The optical lens of claim 1, wherein the focal length f of the first lens ₁ The effective focal length f of the lens meets the following conditions: -5.0<f ₁ /f<-3.0。

10. The optical lens of claim 1, wherein the focal length f of the second lens ₂ The effective focal length f of the lens meets the following conditions: -5.0<f ₂ /f<-3.0。