CN117389008A

CN117389008A - Optical lens

Info

Publication number: CN117389008A
Application number: CN202311688455.2A
Authority: CN
Inventors: 尚博文; 鲍宇旻; 王克民
Original assignee: Jiangxi Lianchuang Electronic Co Ltd
Current assignee: Jiangxi Lianchuang Electronic Co Ltd
Priority date: 2023-12-11
Filing date: 2023-12-11
Publication date: 2024-01-12
Anticipated expiration: 2043-12-11
Also published as: CN117389008B

Abstract

The invention provides an optical lens, which comprises six 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 element with negative refractive power having a convex object-side surface and a concave image-side surface; the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface; a fourth lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a fifth lens with positive focal power, the object side surface of which is a convex surface; a sixth lens element with positive refractive power having a convex image-side surface; the object-side radius of curvature R5 of the third lens and the image-side radius of curvature R6 of the third lens satisfy: 0.3< (R5-R6)/(R5+R6) <0.9. 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

Along with the continuous improvement of the requirements of people on driving experience, the vehicle-mounted application optical lens is increasingly used in intelligent driving, and the position of the vehicle-mounted optical lens in the related industries of automobiles is continuously improved.

Advanced Driving Assistance Systems (ADASs) play an important role in intelligent driving, and collect environmental information through various lenses in combination with sensors to ensure driving safety of drivers. The panoramic lens is used for shooting the environment around the vehicle, pictures captured by a plurality of cameras are finally transmitted to the vehicle-mounted processor for real-time processing, and the pictures are properly corrected, spliced and fused by the processor, so that a continuous, seamless and omnibearing 360-degree panoramic image is generated. The wide-angle lens is generally adopted as the all-round lens, so that the problems of large aberration, large field curvature, poor imaging quality and the like exist, and the user requirement is difficult to meet. Therefore, it is necessary to develop an optical lens with good imaging effect.

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

the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface;

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

a fifth lens with positive focal power, the object side surface of which is a convex surface;

a sixth lens element with positive refractive power having a convex image-side surface;

the object-side curvature radius R5 of the third lens and the image-side curvature radius R6 of the third lens satisfy: 0.3< (R5-R6)/(R5+R6) <0.9.

Further preferably, the object-side radius of curvature R3 of the second lens and the image-side radius of curvature R4 of the second lens satisfy: 0.3< (R3-R4)/(R3+R4) <0.9.

Further preferably, the total optical length TTL of the optical lens and the central thickness CT3 of the third lens along the optical axis satisfy: 0.15< CT3/TTL <0.35.

Further preferably, the optical total length TTL and the effective focal length f of the optical lens satisfy: TTL/f >15.0.

Further preferably, 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 half field angle satisfy: 0.9< ih/(f x θ) <1.2.

Further preferably, the total optical length TTL, the radian θ of the maximum half field angle and the real image height ih corresponding to the maximum half field angle of the optical lens satisfy: 5.0< TTL/ih/θ <5.4.

Further preferably, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -6.5< f1/f < -4.5.

Further preferably, the focal length f4 of the fourth lens and the focal length f5 of the fifth lens satisfy: -1.6< f4/f5< -1.2.

Further preferably, a combined focal length f13 of the first lens, the second lens, and the third lens and a combined focal length f46 of the fourth lens, the fifth lens, and the sixth lens satisfy: 2.0< f13/f46<14.0.

Further preferably, a combined focal length f12 of the first lens and the second lens and a focal length f3 of the third lens satisfy: -0.8< f12/f3< -0.2.

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 is a schematic structural diagram of an optical lens in embodiment 1 of the present invention.

Fig. 2 is a graph showing a field curvature of an optical lens in embodiment 1 of the present invention.

Fig. 3 is an F-Theta distortion curve of the optical lens in embodiment 1 of the present invention.

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

Fig. 5 is an MTF graph of the optical lens in example 1 of the present invention.

Fig. 6 is an axial aberration diagram of the optical lens in embodiment 1 of the present invention.

Fig. 7 is a graph showing a vertical axis chromatic aberration of an optical lens in embodiment 1 of the present invention.

Fig. 8 is a schematic structural diagram of an optical lens in embodiment 2 of the present invention.

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

Fig. 10 is an F-Theta distortion curve of the optical lens in embodiment 2 of the present invention.

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

Fig. 12 is an MTF graph of the optical lens in example 2 of the present invention.

Fig. 13 is an axial aberration diagram of an optical lens in embodiment 2 of the present invention.

Fig. 14 is a vertical axis chromatic aberration chart of the optical lens in embodiment 2 of the present invention.

Fig. 15 is a schematic structural diagram of an optical lens in embodiment 3 of the present invention.

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

FIG. 17 is a graph showing F-Theta distortion of an optical lens in example 3 of the present invention.

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

Fig. 19 is an MTF graph of the optical lens in example 3 of the present invention.

Fig. 20 is an axial aberration diagram of an optical lens in embodiment 3 of the present invention.

Fig. 21 is a graph showing a vertical axis chromatic aberration of an optical lens in embodiment 3 of the present 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 diaphragm, a fourth lens, a fifth lens, a sixth lens, an optical filter and protective glass.

In some embodiments, the first lens element may have a negative optical power, with the object-side surface being convex and the image-side surface being concave. The second lens element may have negative refractive power, wherein the object-side surface thereof is convex and the image-side surface thereof is concave. The third lens element may have positive refractive power, wherein the object-side surface thereof is concave and the image-side surface thereof is convex. The fourth lens element with negative refractive power has a convex object-side surface and a concave image-side surface. The fifth lens element may have positive optical power, and an object-side surface thereof may be convex. The sixth lens may have positive optical power, and an image side surface thereof is convex.

In some embodiments, the object-side radius of curvature R5 of the third lens and the image-side radius of curvature R6 of the third lens satisfy: 0.3< (R5-R6)/(R5+R6) <0.9. The range is satisfied, the light from the edge view field of the second lens can be received as much as possible, meanwhile, the smooth trend of the light is facilitated, and the aberration correction pressure of the rear end lens of the optical lens is reduced.

In some embodiments, the object-side radius of curvature R3 of the second lens and the image-side radius of curvature R4 of the second lens satisfy: 0.3< (R3-R4)/(R3+R4) <0.9. The range is satisfied, the deflection angle of the light can be reduced, and the light trend is more stable; meanwhile, coma and curvature of field can be corrected, the imaging flatness is improved, and the imaging quality of the optical lens is improved.

In some embodiments, the optical total length TTL of the optical lens and the center thickness CT3 of the third lens along the optical axis satisfy: 0.15< CT3/TTL <0.35. The optical lens has the advantages that the correction capability of the optical lens to field curvature can be improved, and meanwhile, the optical lens is favorable for being matched with the third lens with positive focal power, so that more light rays are stably converged to the rear end of the optical lens.

In some embodiments, the optical total length TTL and the effective focal length f of the optical lens satisfy: TTL/f >15.0. Satisfying the above range ensures that the optical lens has a sufficient total length to be designed to meet the requirement of high resolution.

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 half field angle satisfy: 0.9< ih/(f x θ) <1.2. The purpose of large image surface can be realized by meeting the above range.

In some embodiments, the total optical length TTL, the radian θ of the maximum half field angle, and the real image height ih corresponding to the maximum half field angle of the optical lens satisfy: 5.0< TTL/ih/θ <5.4. Satisfying the above range balances the relationship between the optical lens image height, the optical total length, and the angle of view.

In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -6.5< f1/f < -4.5. The above range is satisfied, so that the first lens has proper negative focal power, which is favorable for forming a short focal length lens structure so as to enable light rays with large visual angles to enter the optical lens.

In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -5.0< f2/f < -4.0. The range is satisfied, so that the second lens has proper negative focal power, and the negative focal power of the first lens can be shared, so that light rays with large field angle can smoothly enter the optical lens, and the light receiving range is enlarged.

In some embodiments, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: 5.0< f3/f <8.0. The range is satisfied, so that the third lens has proper positive focal power, and the negative focal power at the front end of the optical lens can be balanced, so that light rays with large field angles can smoothly enter the rear end of the optical lens.

In some embodiments, the focal length f4 of the fourth lens and the focal length f5 of the fifth lens satisfy: -1.6< f4/f5< -1.2. The range is satisfied, the focal length is close, and the formation of the cemented lens is facilitated, and the chromatic aberration of the optical lens is improved.

In some embodiments, the combined focal length f13 of the first, second, and third lenses and the combined focal length f46 of the fourth, fifth, and sixth lenses satisfy: 2.0< f13/f46<14.0. The above range is satisfied, and aberration and chromatic aberration in the optical system are reduced, thereby improving imaging quality. Because the lens combination focal length before the diaphragm is larger, spherical aberration and coma can be corrected more effectively. Meanwhile, as the focal length of the lens combination behind the diaphragm is smaller, chromatic aberration can be better corrected, so that the color reproducibility and color reproducibility of the optical system are improved.

In some embodiments, the combined focal length f12 of the first lens and the second lens and the focal length f3 of the third lens satisfy: -0.8< f12/f3< -0.2. Satisfying the above range, it can be ensured that the off-axis aberration generated by the third lens to the front lens of the optical lens is not excessively corrected, thereby resulting in a reduction of the image height of the optical lens; meanwhile, better aberration correction capability can be provided, and the imaging quality of the optical lens is improved.

In some embodiments, the fourth lens and the fifth 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 stop ST, a fourth lens L4, a fifth lens L5, a sixth lens L6, an optical filter G1, and a cover glass 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, wherein an object-side surface S5 thereof is concave, and an image-side surface S6 thereof is convex;

a diaphragm ST;

the fourth lens element L4 has negative refractive power, wherein an object-side surface S7 thereof is convex, and an image-side surface S8 thereof is concave;

the fifth lens element L5 has positive refractive power, wherein an object-side surface S8 thereof is convex, and an image-side surface S9 thereof is concave;

the fourth lens element L4 and the fifth lens element L5 form a cemented lens assembly, i.e., a cemented surface between the image side surface of the fourth lens element L4 and the object side surface of the fifth lens element L5 is S8;

the sixth lens element L6 with positive refractive power has a convex object-side surface S10 and a convex image-side surface S11;

the object side surface S12 and the image side surface S13 of the optical filter G1 are planes;

the object side surface S14 and the image side surface S15 of the protective glass G2 are planes;

the imaging surface S16 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

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. 2, 3, 4, 5, 6, and 7, respectively.

Fig. 2 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-0.1 mm to 0.05mm, which indicates that the optical lens can well correct the field curvature.

Fig. 3 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 figure, the F-Theta distortion of the optical lens is controlled within-5% -0, the image compression of the edge angle area is gentle, and the definition of the unfolded image is effectively improved.

Fig. 4 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 50% at the maximum half field angle, which indicates that the optical lens has better relative illuminance.

Fig. 5 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. 6 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-30 mu m to 5 mu m, which indicates that the optical lens can better correct the axial aberration.

Fig. 7 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 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 excellently correct chromatic aberration of the marginal field of view and the secondary spectrum of the whole image surface.

Example 2

Referring to fig. 8, a schematic structural diagram of an optical lens provided in embodiment 2 of the present invention is shown, and compared with embodiment 1, the difference is that: the image side surface S9 of the fifth lens element L5 is convex, the object side surface S10 of the sixth lens element L6 is concave, and the optical parameters such as the radius of curvature and the lens thickness of the lens surfaces are different.

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

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. 9, 10, 11, 12, 13, and 14, respectively.

Fig. 9 shows a field curvature curve of example 2, 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 +/-0.05 mm, which indicates that the optical lens can well correct the field curvature.

Fig. 10 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 0-20%, the image compression of the edge angle area is gentle, and the definition of the unfolded image is effectively improved.

Fig. 11 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 50% at the maximum half field angle, which indicates that the optical lens has better relative illuminance.

Fig. 12 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. 13 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-20 mu m to 10 mu m, which indicates that the optical lens can better correct the axial aberration.

Fig. 14 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 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 excellently correct chromatic aberration of the marginal field of view and the secondary spectrum of the whole image surface.

Example 3

Referring to fig. 15, a schematic structural diagram of an optical lens provided in embodiment 3 of the present invention is shown, and compared with embodiment 1, the difference is that: the image side surface S9 of the fifth lens element L5 is convex, the object side surface S10 of the sixth lens element L6 is concave, and the optical parameters such as the radius of curvature and the lens thickness of the lens surfaces are different.

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

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. 16, 17, 18, 19, 20, and 21, respectively.

Fig. 16 shows a field curvature curve of example 3, 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-0.05 mm to 0.06mm, which indicates that the optical lens can well correct the field curvature.

Fig. 17 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 0-20%, the image compression of the edge angle area is gentle, and the definition of the unfolded image is effectively improved.

Fig. 18 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 (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 50% at the maximum half field angle, which indicates that the optical lens has better relative illuminance.

Fig. 19 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. 20 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 figure, the offset of the axial aberration is controlled within-20 mu m to 5 mu m, which indicates that the optical lens can better correct the axial aberration.

Fig. 21 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 2 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 4, 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 corresponding to the maximum half field angle, the chief ray incident angle CRA, the maximum field angle FOV, and the numerical values corresponding to each condition in each embodiment.

TABLE 4 Table 4

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 six lenses in order from an object side to an imaging surface along an optical axis, comprising:

2. The optical lens of claim 1, wherein the object-side radius of curvature R3 of the second lens and the image-side radius of curvature R4 of the second lens satisfy: 0.3< (R3-R4)/(R3+R4) <0.9.

3. The optical lens of claim 1, wherein an optical total length TTL of the optical lens and a center thickness CT3 of the third lens along an optical axis satisfy: 0.15< CT3/TTL <0.35.

4. The optical lens of claim 1, wherein the optical total length TTL and the effective focal length f of the optical lens satisfy: TTL/f >15.0.

5. The optical lens according to claim 1, wherein the effective focal length f of the optical lens satisfies the following conditions: 0.9< ih/(f x θ) <1.2.

6. The optical lens according to claim 1, wherein the total optical length TTL, the radian θ of the maximum half field angle, and the true image height ih corresponding to the maximum half field angle of the optical lens satisfy: 5.0< TTL/ih/θ <5.4.

7. The optical lens of claim 1, wherein an effective focal length f of the optical lens and a focal length f1 of the first lens satisfy: -6.5< f1/f < -4.5.

8. The optical lens of claim 1, wherein a focal length f4 of the fourth lens and a focal length f5 of the fifth lens satisfy: -1.6< f4/f5< -1.2.

9. The optical lens of claim 1, wherein a combined focal length f13 of the first lens, the second lens, and the third lens and a combined focal length f46 of the fourth lens, the fifth lens, and the sixth lens satisfy: 2.0< f13/f46<14.0.

10. The optical lens of claim 1, wherein a combined focal length f12 of the first lens and the second lens and a focal length f3 of the third lens satisfy: -0.8< f12/f3< -0.2.