CN115291372B - Optical lens - Google Patents
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- CN115291372B CN115291372B CN202211219851.6A CN202211219851A CN115291372B CN 115291372 B CN115291372 B CN 115291372B CN 202211219851 A CN202211219851 A CN 202211219851A CN 115291372 B CN115291372 B CN 115291372B
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
- G02B13/002—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface
- G02B13/0045—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface having five or more lenses
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/06—Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
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Abstract
The invention provides an optical lens, which comprises three groups of lens groups in total, wherein the three groups of lens groups are as follows from an object side to an imaging surface along an optical axis in sequence: the first lens group having negative power includes: the image side surface of the first lens is a concave surface; a second lens with negative focal power, wherein the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a convex surface; a diaphragm; the second lens group having positive optical power includes: the image side surface of the third lens is a convex surface; a fourth lens having positive refractive power, both of an object-side surface and an image-side surface of which are convex surfaces; the third lens group having positive optical power includes: a fifth lens having a negative refractive power, an image-side surface of which is concave; a sixth lens element having a positive refractive power, wherein both the object-side surface and the image-side surface are convex; a seventh lens element having a refractive power, the object-side surface of which is concave and the image-side surface of which is convex; the eighth lens with focal power has a convex object-side surface and a concave image-side surface. The optical lens has the advantages of large field angle, large aperture, high definition and high imaging quality.
Description
Technical Field
The invention relates to the technical field of imaging lenses, in particular to an optical lens.
Background
With the rapid development of Advanced Driving Assistance Systems (ADAS), the vehicle-mounted lens has wider application and development. The method comprises a vehicle data recorder, automatic parking, front vehicle collision early warning (FCW), lane departure early warning (LDW), pedestrian detection early warning (PCW) and the like. Although the conventional wide-angle vehicle-mounted lens can basically meet the basic requirement of using the large-field vehicle-mounted lens, the conventional wide-angle vehicle-mounted lens still has many defects, such as too small field angle or aperture, insufficient resolution and the like.
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, high definition, and high imaging quality.
To achieve the above object, the present invention provides an optical lens assembly, which includes three groups of lens assemblies, in order from an object side to an image plane along an optical axis:
the first lens group having negative power includes: the image side surface of the first lens is a concave surface; a second lens with negative focal power, wherein the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a convex surface;
a diaphragm;
the second lens group having positive optical power includes: the image side surface of the third lens is a convex surface; a fourth lens having positive refractive power, both of an object-side surface and an image-side surface of which are convex surfaces;
the third lens group having positive optical power includes: a fifth lens having a negative refractive power, an image-side surface of which is concave; a sixth lens element having a positive refractive power, wherein both the object-side surface and the image-side surface are convex; a seventh lens element with a focal power, wherein the object-side surface of the seventh lens element is concave and the image-side surface of the seventh lens element is convex; and an eighth lens element with a refractive power, wherein the object-side surface is convex and the image-side surface is concave.
Preferably, the total optical length TTL and the effective focal length f of the optical lens satisfy: TTL/f is more than 4.0 and less than 5.0.
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 1.6 and less than 1.8.
Preferably, the optical back focus BFL and the effective focal length f of the optical lens satisfy: BFL/f is more than 0.4 and less than 0.7.
Preferably, the maximum field angle FOV of the optical lens and the effective working aperture D of the object side surface of the first lens 1 And the real image height IH corresponding to the maximum field angle satisfies the following conditions: d is more than 0.55 1 /IH/tan(FOV/2)＜0.65。
Preferably, the focal length f of the first lens group G1 Focal length f of the second lens group G2 Satisfies the following conditions: -1.3 < f G1 /f G2 ＜0.7。
Preferably, an effective focal length f of the optical lens and a focal length f of the third lens group G3 Satisfies the following conditions: f is more than 5.0 G3 /f＜10.0。
Preferably, the effective focal length f of the optical lens and the focal length f of the seventh lens element 7 Satisfies the following conditions: 2.0 < | f 7 /f|。
Preferably, the effective focal length f of the optical lens and the focal length f of the eighth lens element 8 Satisfies the following conditions: 2.5 < | f 8 /f|。
Preferably, the total optical length TTL of the optical lens and the sum Σ CT of the central thicknesses of the first lens element to the eighth lens element along the optical axis satisfy: 0.5 <. Sigma CT/TTL < 0.8.
Compared with the prior art, the invention has the beneficial effects that: the optical lens realizes the effects of large field angle, large aperture, high definition and high imaging quality 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 F-tan θ distortion of an optical lens in example 1 of the present invention;
fig. 4 is a graph showing a relative illuminance curve of the optical lens in embodiment 1 of the present invention;
fig. 5 is a MTF graph of the optical lens in embodiment 1 of the present invention;
fig. 6 is a graph showing axial aberration of the optical lens in embodiment 1 of the present invention;
fig. 7 is a vertical axis chromatic aberration curve diagram of the optical lens in embodiment 1 of the present invention;
fig. 8 is a schematic structural diagram of an optical lens system according to embodiment 2 of the present invention;
FIG. 9 is a graph of curvature of field of an optical lens in embodiment 2 of the present invention;
FIG. 10 is a graph showing F-tan θ distortion of an optical lens in example 2 of the present invention;
fig. 11 is a graph showing a relative illumination of an optical lens in embodiment 2 of the present invention;
fig. 12 is a MTF graph of an optical lens in embodiment 2 of the present invention;
fig. 13 is a graph showing axial aberration of the optical lens in embodiment 2 of the present invention;
FIG. 14 is a vertical axis chromatic aberration diagram of an optical lens in embodiment 2 of the present invention;
fig. 15 is a schematic structural view of an optical lens system according to embodiment 3 of the present invention;
fig. 16 is a graph of curvature of field of the optical lens in embodiment 3 of the present invention;
FIG. 17 is a graph showing F-tan θ distortion of an optical lens in embodiment 3 of the present invention;
fig. 18 is a graph showing the relative illumination of the optical lens in embodiment 3 of the present invention;
fig. 19 is a MTF graph of an optical lens in embodiment 3 of the present invention;
FIG. 20 is a graph showing axial aberrations of an optical lens unit according to embodiment 3 of the present invention;
FIG. 21 is a vertical axis chromatic aberration diagram of an optical lens in embodiment 3 of the present invention;
fig. 22 is a schematic structural diagram of an optical lens system according to embodiment 4 of the present invention;
FIG. 23 is a graph of curvature of field of an optical lens in embodiment 4 of the present invention;
FIG. 24 is a graph showing F-tan θ distortion of an optical lens in embodiment 4 of the present invention;
fig. 25 is a graph showing the relative illuminance of the optical lens in embodiment 4 of the present invention;
fig. 26 is a MTF graph of an optical lens in embodiment 4 of the present invention;
fig. 27 is a graph showing axial aberration of the optical lens in embodiment 4 of the present invention;
fig. 28 is a vertical axis chromatic aberration diagram of the optical lens in embodiment 4 of the present invention.
The following detailed description will further illustrate the invention in conjunction with the above-described figures.
Detailed Description
For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of embodiments of the application and does not limit the scope of the application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.
It should be noted that in this specification the expressions first, second, third etc. are only used to distinguish one feature from another, and do not represent any limitation on the features. Thus, the first lens discussed below may also be referred to as the second lens or the third lens without departing from the teachings of the present invention.
In the drawings, the thickness, size, and shape of the lens have been slightly exaggerated for convenience of explanation. In particular, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings. The figures are purely diagrammatic and not drawn to scale.
Herein, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.
It will be further understood that the terms "comprises," "comprising," "has," "having," "includes" and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Moreover, when a statement such as "at least one of" appears after a list of listed features, the entirety of the listed features is modified rather than modifying individual elements in the list. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to 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 present application, the embodiments and features of the embodiments may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
The optical lens according to the embodiment of the present invention includes, in order from an object side to an image side: the lens system comprises a first lens group G1 with negative focal power, a diaphragm ST, a second lens group G2 with positive focal power, a third lens group G3 with positive focal power and a filter A1.
The first lens group G1 includes: a first lens having a negative refractive power, an image-side surface of which is concave; the second lens with negative focal power has a concave object-side surface and a convex image-side surface.
The second lens group G2 includes: a third lens element L3 having a positive refractive power and having a convex image-side surface; the fourth lens element L4 having positive refractive power has a convex object-side surface and a convex image-side surface.
The third lens group G3 includes: a fifth lens having a negative refractive power, an image-side surface of which is concave; a sixth lens element having a positive refractive power, wherein both the object-side surface and the image-side surface are convex; a seventh lens element having a refractive power, the object-side surface of which is concave and the image-side surface of which is convex; the eighth lens with focal power has a convex object-side surface and a concave image-side surface.
In some embodiments, a stop for limiting light beams may be disposed between the first lens group G1 and the second lens group G2, so as to reduce ghost images of the optical lens, facilitate converging light entering the optical system, and reduce the diameter of the rear end of the optical lens.
In some embodiments, the fifth lens and the sixth lens can be cemented to form a cemented lens, which can effectively correct chromatic aberration of the optical lens, reduce eccentricity sensitivity of the optical lens, balance aberration of the optical lens, and improve imaging quality of the optical lens; the assembly sensitivity of the optical lens can be reduced, the processing difficulty of the optical lens is further reduced, and the assembly yield of the optical lens is improved.
In some embodiments, the total optical length TTL and the effective focal length f of the optical lens satisfy: TTL/f is more than 4.0 and less than 5.0. The optical lens can effectively limit the length of the lens and is beneficial to realizing the miniaturization of the optical lens.
In some embodiments, the real image height IH at which the effective focal length f of the optical lens corresponds to the maximum field angle satisfies: IH/f is more than 1.6 and less than 1.8. Satisfying the above range can make the optical lens not only give consideration to the characteristics of a large image plane, but also have good imaging quality.
In some embodiments, the optical back focus BFL and the effective focal length f of the optical lens satisfy: BFL/f is more than 0.4 and less than 0.7. The method meets the range, is favorable for obtaining balance between good imaging quality and optical back focal length easy to assemble, and reduces the difficulty of the camera module assembly process while ensuring the imaging quality of the optical lens.
In some embodiments, the maximum field angle FOV of the optical lens, the object side effective working aperture D of the first lens 1 And the real image height IH corresponding to the maximum field angle satisfies the following conditions: d is more than 0.55 1 IH/Tan (FOV/2) < 0.65. The optical lens has the advantages that the optical lens has a large field angle and a large image plane, the front port diameter is small, and the miniaturization of the optical lens is facilitated.
In some embodiments, the effective focal length f of the optical lens and the focal length f of the first lens are different 1 Satisfies the following conditions: -2.0 < f 1 The/f is less than 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 field angle of the optical lens.
In some embodiments, the effective focal length f of the optical lens and the focal length f of the second lens are different 2 Satisfies the following conditions: -45.0 < f 2 And/f < -7.0. The second lens has proper negative focal power and can share the negative focal power of the first lens group of the optical lens, so that the overlarge light ray deflection caused by the excessively concentrated focal power of the first lens is avoided, and the difficulty in correcting chromatic aberration of the optical lens is reduced.
In some embodiments, the effective focal length f of the optical lens and the focal length f of the third lens are 3 Satisfies the following conditions: f is more than 0 3 The/f is less than 2.5. The third lens has appropriate positive focal power, so that stable light transition is facilitated, astigmatism can be corrected conveniently, and the imaging quality of the optical lens is improved.
In some embodiments, the effective focal length f of the optical lens and the focal length f of the fourth lens are 4 Satisfies the following conditions: f is more than 0 4 The/f is less than 3.0. Satisfy above-mentioned scope, can make the fourth lens have appropriate positive focal power, be favorable to the smooth transition of light, be convenient for to the correction of curvature of field, promote optical lens's imaging quality.
In some embodiments, the effective focal length f of the optical lens and the focal length f of the fifth lens 5 Satisfies the following conditions: -2.0 < f 5 The/f is less than 0. The fifth lens has appropriate negative focal power, so that the imaging area of the optical lens can be increased, and the imaging quality of the optical lens can be improved.
In some embodiments, the effective focal length f of the optical lens and the focal length f of the sixth lens element 6 Satisfies the following conditions: f is more than 0 6 The/f is less than 1.5. The sixth lens has appropriate positive focal power, light can be smoothly transited, spherical aberration and field curvature of the fifth lens are balanced, and imaging quality of the optical lens is improved.
In some embodiments, the effective focal length f of the optical lens and the focal length f of the seventh lens 7 Satisfies the following conditions: 2.0 < | f 7 And/f |. Satisfying above-mentioned scope, can making the seventh lens have appropriate focal power, be favorable to balanced optical lens's coma and astigmatism, promote optical lens's imaging quality.
In some embodiments, the effective focal length f of the optical lens and the focal length f of the eighth lens element 8 Satisfies the following conditions: 2.5 < | f 8 And/f |. Satisfying the above range, the eighth lens can have a proper focal power, which is beneficial to balance coma and astigmatism of the optical lens and improve the imaging quality of the optical lens.
In some embodiments, the focal length f of the first lens group G1 G1 Focal length f of the second lens group G2 G2 Satisfies the following conditions: -1.3 < f G1 /f G2 Is less than 0.7. Satisfy the above range, the diaphragm can be madeThe focal length distribution of the front lens group and the rear lens group is close, so that the light is gentle and excessive, and the imaging quality of the optical lens is improved.
In some embodiments, the effective focal length f of the optical lens and the focal length f of the third lens group G3 G3 Satisfies the following conditions: f is more than 5.0 G3 The/f is less than 10.0. Satisfy above-mentioned scope, through the focus of each lens of rational distribution third lens group, can control the angle of emergent ray, can make the tolerance error numerical value between CRA of zoom lens and the CRA of chip photosensitive element great, promote zoom lens to image sensor's adaptability.
In some embodiments, the rise Sag of the image-side surface of the eighth lens 16 And light passing half aperture d 16 Satisfies the following conditions: sag of 0 16 /d 16 Is less than 0.1. Satisfy above-mentioned scope, can effectively retrain the face type of the image side off-axis visual field of eighth lens, guarantee that marginal visual field light has sufficient deflection angle when passing through eighth lens, guarantee that the angle of incidence angle when light incides to the image forming surface is less to ensure that optical lens has great relative illuminance, promote optical lens's imaging quality.
In some embodiments, the total optical length TTL of the optical lens and the sum Σ CT of the central thicknesses of the first lens element to the eighth lens element along the optical axis respectively satisfy: 0.5 <. Sigma CT/TTL < 0.8. The optical lens structure meets the range, can effectively compress the total length of the optical lens, and is beneficial to the structural design and the production process of the optical lens.
In order to make the system have better optical performance, a plurality of aspheric lenses are adopted in the lens, and the surface shapes of the aspheric surfaces of the optical lens satisfy the following equation:
wherein z is the distance between the curved surface and the vertex of the curved surface in the optical axis direction, h is the distance between the optical axis and the curved surface, C is the curvature of the vertex of the curved surface, K is a quadric coefficient, and A, B, C, D, E and F are second-order, fourth-order, sixth-order, eighth-order, tenth-order and twelfth-order curved coefficients respectively.
The invention is further illustrated below by means of a number of examples. In various embodiments, the thickness, the curvature radius, and the material selection part of each lens in the optical lens are different, and specific differences can be referred to the parameter tables of the various embodiments. The following examples are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the following examples, and any other changes, substitutions, combinations or simplifications which do not depart from the gist of the present invention should be construed as being equivalent replacements within the scope of the present invention.
Example 1
Referring to fig. 1, a schematic structural diagram of an optical lens system according to embodiment 1 of the present invention is shown, the optical lens system sequentially includes, from an object side to an image plane along an optical axis: a first lens group G1 with negative focal power, a diaphragm ST, a second lens group G2 with positive focal power, a third lens group G3 with positive focal power and a filter A1. The first lens group G1 comprises a first lens L1 and a second lens L2; the second lens group G2 includes a third lens L3 and a fourth lens L4; the third lens group G3 includes a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8.
The first lens L1 has negative focal power, and both the object side surface S1 and the image side surface S2 are concave surfaces;
the second lens L2 has negative focal power, and the object side surface S3 is a concave surface, and the image side surface S4 is a convex surface;
a diaphragm ST;
the third lens L3 has positive focal power, and the object-side surface S5 is a concave surface, and the image-side surface S6 is a convex surface;
the fourth lens L4 has positive focal power, and both the object side surface S7 and the image side surface S8 are convex surfaces;
the fifth lens L5 has negative focal power, and both the object-side surface S9 and the image-side surface S10 are concave;
the sixth lens L6 has positive focal power, and both the object-side surface S11 and the image-side surface S12 are convex surfaces;
the seventh lens element L7 has positive refractive power, and has a concave object-side surface S13 and a convex image-side surface S14;
the eighth lens element L8 has a negative refractive power, and has a convex object-side surface S15 and a concave image-side surface S16;
the fifth lens L5 and the sixth lens L6 can be cemented to form a cemented lens;
the object side surface S17 and the image side surface S18 of the optical filter A1 are both planes;
the image formation surface S19 is a plane.
The relevant parameters of each lens in the optical lens in example 1 are shown in table 1-1.
TABLE 1-1
The surface shape parameters of the aspherical lens of the optical lens in example 1 are shown in table 1-2.
Tables 1 to 2
In this embodiment, the curvature of field curve, F-tan θ distortion, relative illumination, MTF, axial aberration, and homeotropic aberration of the optical lens are shown in fig. 2, 3, 4, 5, 6, and 7, respectively.
Fig. 2 shows a field curvature curve of example 1, which indicates the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis indicating a shift amount (unit: mm) and the vertical axis indicating a half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.05 mm, which shows that the optical lens can excellently correct the field curvature.
Fig. 3 shows an F-tan θ distortion curve of example 1, which shows F-tan θ distortions at different image heights on an image forming plane for light rays of different wavelengths, with the abscissa representing the F-tan θ distortion (unit:%) and the ordinate representing the half field angle (unit: °). As can be seen from the figure, the F-tan theta distortion of the optical lens is controlled within 40%, the trend of the F-tan theta distortion curve is smooth, the image compression of the edge large-angle area is smooth, the definition of the expanded image is effectively improved, and the optical lens can better correct the F-tan theta distortion.
Fig. 4 shows a relative illuminance curve of example 1, which represents relative illuminance values at different angles of field of view on the imaging plane, with the horizontal axis representing the half field angle (unit: °) and the vertical axis representing the relative illuminance (unit:%). As can be seen from the figure, the relative luminance value of the optical lens at the maximum half field angle is still greater than 70%, indicating that the optical lens has good relative luminance.
Fig. 5 shows MTF (modulation transfer function) graphs of embodiment 1, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.3 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve uniformly and smoothly drops in the process of the field of view from the center to the edge, and the MTF has better imaging quality and better detail resolution capability under the conditions of low frequency and high frequency.
Fig. 6 shows an axial aberration curve of example 1, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: μm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the amount of shift of the axial aberration is controlled within ± 10 μm, indicating that the optical lens can correct the axial aberration well.
Fig. 7 shows a vertical axis chromatic aberration curve of example 1, which shows chromatic aberration at different image heights on an image forming plane for each wavelength with respect to a center wavelength (0.55 μm), the horizontal axis shows a vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis shows a normalized angle of view. As can be seen from the figure, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within +/-3 mu m, which shows that the optical lens can effectively correct the chromatic aberration of the marginal field of view and the secondary spectrum of the whole image plane.
Example 2
Referring to fig. 8, a schematic structural diagram of an optical lens system provided in this embodiment 2 is shown, the optical lens system sequentially includes, from an object side to an image plane along an optical axis: a first lens group G1 with negative focal power, a diaphragm ST, a second lens group G2 with positive focal power, a third lens group G3 with positive focal power and a filter A1. The first lens group G1 comprises a first lens L1 and a second lens L2; the second lens group G2 includes a third lens L3 and a fourth lens L4; the third lens group G3 includes a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8.
The first lens L1 has negative focal power, and both the object side surface S1 and the image side surface S2 are concave surfaces;
the second lens L2 has negative focal power, the object side surface S3 is a concave surface, and the image side surface S4 is a convex surface;
a diaphragm ST;
the third lens L3 has positive focal power, and the object side surface S5 is a concave surface, and the image side surface S6 is a convex surface;
the fourth lens L4 has positive focal power, and both the object-side surface S7 and the image-side surface S8 are convex surfaces;
the fifth lens L5 has negative focal power, and both the object-side surface S9 and the image-side surface S10 are concave;
the sixth lens L6 has positive focal power, and both the object-side surface S11 and the image-side surface S12 are convex surfaces;
the seventh lens element L7 has positive refractive power, and has a concave object-side surface S13 and a convex image-side surface S14;
the eighth lens element L8 has negative refractive power, and has a convex object-side surface S15 and a concave image-side surface S16;
the fifth lens L5 and the sixth lens L6 may be cemented to constitute a cemented lens.
The relevant parameters of each lens in the optical lens in embodiment 2 are shown in table 2-1.
TABLE 2-1
The 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 field curvature graph, an F-tan θ distortion curve, a relative illumination graph, an MTF graph, an axial aberration graph, and a vertical axis chromatic aberration graph of the optical lens are respectively shown in fig. 9, fig. 10, fig. 11, fig. 12, fig. 13, and fig. 14.
Fig. 9 shows a field curvature curve of example 2, which indicates the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis indicating the amount of displacement (unit: mm) and the vertical axis indicating 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 shows that the optical lens can excellently correct the field curvature.
Fig. 10 shows an F-tan θ distortion curve of example 2, which shows F-tan θ distortions at different image heights on an image forming plane for light rays of different wavelengths, with the abscissa representing the F-tan θ distortion (unit:%) and the ordinate representing the half field angle (unit: °). As can be seen from the figure, the F-tan theta distortion of the optical lens is controlled within 40%, the trend of the F-tan theta distortion curve is smooth, the image compression of the edge large-angle area is smooth, the definition of the expanded image is effectively improved, and the optical lens can better correct the F-tan theta distortion.
Fig. 11 shows a relative illuminance curve of example 2, which represents relative illuminance values at different angles of field of view on an imaging plane, with the horizontal axis representing a half field angle (unit: °) and the vertical axis representing the relative illuminance (unit:%). As can be seen from the figure, the relative luminance value of the optical lens at the maximum half field angle is still greater than 70%, indicating that the optical lens has good relative luminance.
Fig. 12 shows MTF (modulation transfer function) graphs of embodiment 2, which represent lens imaging modulation degrees of different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing MTF values. As can be seen from the figure, the MTF value of the embodiment is above 0.3 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly reduced in the process from the center to the edge field of view, and the image has better imaging quality and better detail resolution capability under the conditions of low frequency and high frequency.
Fig. 13 shows an axial aberration curve of example 2, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: μm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the amount of shift of the axial aberration is controlled within ± 10 μm, indicating that the optical lens can excellently correct the axial aberration.
Fig. 14 shows a vertical axis chromatic aberration curve of example 2, which shows chromatic aberration at different image heights on an image forming plane for each wavelength with respect to a center wavelength (0.55 μm), the horizontal axis shows a vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis shows a normalized angle of view. As can be seen from the figure, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within +/-3 mu m, which shows that the optical lens can effectively correct the chromatic aberration of the marginal field of view and the secondary spectrum of the whole image plane.
Example 3
Referring to fig. 15, a schematic structural diagram of an optical lens system provided in embodiment 3 is shown, the optical lens system sequentially includes, from an object side to an image plane along an optical axis: the lens system comprises a first lens group G1 with negative focal power, a diaphragm ST, a second lens group G2 with positive focal power, a third lens group G3 with positive focal power and a filter A1. The first lens group G1 comprises a first lens L1 and a second lens L2; the second lens group G2 includes a third lens L3, a fourth lens L4; the third lens group G3 includes a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8.
The first lens L1 has negative focal power, and the object side surface S1 is a convex surface, and the image side surface S2 is a concave surface;
the second lens L2 has negative focal power, the object side surface S3 is a concave surface, and the image side surface S4 is a convex surface;
a diaphragm ST;
the third lens L3 has positive focal power, and both the object side surface S5 and the image side surface S6 are convex surfaces;
the fourth lens L4 has positive focal power, and both the object side surface S7 and the image side surface S8 are convex surfaces;
the fifth lens L5 has negative focal power, and the object side surface S9 is a convex surface, and the image side surface S10 is a concave surface;
the sixth lens L6 has positive focal power, and both the object-side surface S11 and the image-side surface S12 are convex surfaces;
the seventh lens element L7 has a negative power, and has a concave object-side surface S13 and a convex image-side surface S14;
the eighth lens element L8 has a negative refractive power, and has a convex object-side surface S15 and a concave image-side surface S16;
the fifth lens L5 and the sixth lens L6 may be cemented to constitute a cemented lens.
The relevant parameters of each lens in the optical lens in example 3 are shown in table 3-1.
TABLE 3-1
The parameters of the surface shape of the aspherical lens of the optical lens in example 3 are shown in table 3-2.
TABLE 3-2
In the present embodiment, a field curvature graph, an F-tan θ distortion curve, a relative illuminance graph, an MTF graph, an axial aberration graph, and a vertical axis chromatic aberration graph of the optical lens are shown in fig. 16, 17, 18, 19, 20, and 21, respectively.
Fig. 16 shows a field curvature curve of example 3, which shows the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis representing the amount of displacement (unit: mm) and the vertical axis representing the half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.10 mm, which shows that the optical lens can excellently correct the field curvature.
Fig. 17 shows an F-tan θ distortion curve of example 3, which shows the F-tan θ distortion of light rays of different wavelengths at different image heights on an image forming plane, with the horizontal axis showing the F-tan θ distortion (unit:%) and the vertical axis showing the half field angle (unit:%). As can be seen from the figure, the F-tan theta distortion of the optical lens is controlled within 40%, the trend of the F-tan theta distortion curve is smooth, the image compression of the edge large-angle area is smooth, the definition of the expanded image is effectively improved, and the optical lens can better correct the F-tan theta distortion.
Fig. 18 shows a relative illuminance curve of example 3, which represents relative illuminance values at different angles of field of view on the imaging plane, with the horizontal axis representing the half field angle (unit: °) and the vertical axis representing the relative illuminance (unit:%). As can be seen from the figure, the relative luminance value of the optical lens at the maximum half field angle is still greater than 70%, indicating that the optical lens has good relative luminance.
Fig. 19 shows MTF (modulation transfer function) graphs of embodiment 3, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.4 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly reduced in the process from the center to the edge field of view, and the image quality and the detail resolution capability are good under the conditions of low frequency and high frequency.
Fig. 20 shows an axial aberration curve of example 3, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: μm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the shift amount of the axial aberration is controlled within ± 20 μm, which indicates that the optical lens can correct the axial aberration well.
Fig. 21 shows a vertical axis chromatic aberration curve of example 3, which shows chromatic aberration at different image heights on an image forming plane for each wavelength with respect to a center wavelength (0.55 μm), the horizontal axis shows a vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis shows a normalized angle of view. As can be seen from the figure, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within +/-5 mu m, which shows that the optical lens can effectively correct the chromatic aberration of the marginal field of view and the secondary spectrum of the whole image plane.
Example 4
Fig. 22 is a schematic structural diagram of an optical lens system provided in this embodiment 4, which includes, in order from an object side to an image plane along an optical axis: a first lens group G1 with negative focal power, a diaphragm ST, a second lens group G2 with positive focal power, a third lens group G3 with positive focal power and a filter A1. The first lens group G1 comprises a first lens L1 and a second lens L2; the second lens group G2 includes a third lens L3, a fourth lens L4; the third lens group G3 includes a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8.
The first lens L1 has negative focal power, and the object side surface S1 is a convex surface, and the image side surface S2 is a concave surface;
the second lens L2 has negative focal power, the object side surface S3 is a concave surface, and the image side surface S4 is a convex surface;
a diaphragm ST;
the third lens L3 has positive focal power, and both the object side surface S5 and the image side surface S6 are convex surfaces;
the fourth lens L4 has positive focal power, and both the object-side surface S7 and the image-side surface S8 are convex surfaces;
the fifth lens L5 has negative focal power, and the object side surface S9 is a convex surface, and the image side surface S10 is a concave surface;
the sixth lens L6 has positive focal power, and both the object-side surface S11 and the image-side surface S12 are convex surfaces;
the seventh lens element L7 has negative power, and has a concave object-side surface S13 and a convex image-side surface S14;
the eighth lens element L8 has positive refractive power, and has a convex object-side surface S15 and a concave image-side surface S16;
the fifth lens L5 and the sixth lens L6 may be cemented to constitute a cemented lens.
The relevant parameters of each lens in the optical lens in example 4 are shown in table 4-1.
TABLE 4-1
The surface shape parameters of the aspherical lens of the optical lens in example 4 are shown in table 4-2.
TABLE 4-2
In the present embodiment, the curvature of field curve, F-tan θ distortion curve, relative illumination curve, MTF curve, axial aberration curve, and vertical axis chromatic aberration curve of the optical lens are respectively shown in fig. 23, 24, 25, 26, 27, and 28.
Fig. 23 shows a field curvature curve of example 4, which shows the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, with the horizontal axis representing the amount of displacement (unit: mm) and the vertical axis representing the half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.10 mm, which shows that the optical lens can better correct the field curvature.
Fig. 24 shows an F-tan θ distortion curve of example 4, which shows the F-tan θ distortion of light rays of different wavelengths at different image heights on an image forming plane, with the horizontal axis showing the F-tan θ distortion (unit:%) and the vertical axis showing the half field angle (unit:%). It can be seen from the figure that the F-tan θ distortion of the optical lens is controlled within 40%, the trend of the F-tan θ distortion curve is smooth, the image compression in the large-angle edge area is smooth, the definition of the expanded image is effectively improved, and the optical lens can better correct the F-tan θ distortion.
Fig. 25 shows a relative illuminance curve of example 4, which represents relative illuminance values at different angles of field of view on the imaging plane, with the horizontal axis representing the half field angle (unit: °), and the vertical axis representing the relative illuminance (unit:%). As can be seen from the figure, the relative luminance value of the optical lens is still greater than 80% at the maximum half field angle, indicating that the optical lens has excellent relative luminance.
Fig. 26 shows MTF (modulation transfer function) graphs of embodiment 4, which represent the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.3 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly reduced in the process from the center to the edge field of view, and the image quality and the detail resolution capability are better under the conditions of low frequency and high frequency.
Fig. 27 shows an axial aberration curve of example 4, which represents the aberration on the optical axis at the imaging plane for each wavelength, with the horizontal axis representing the axial aberration value (unit: μm) and the vertical axis representing the normalized pupil radius. As can be seen from the figure, the shift amount of the axial aberration is controlled within ± 20 μm, which indicates that the optical lens can excellently correct the axial aberration.
Fig. 28 shows a vertical axis chromatic aberration curve of example 4, which shows chromatic aberration at different image heights on an image forming plane for each wavelength with respect to a center wavelength (0.55 μm), the horizontal axis shows a vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis shows a normalized angle of view. As can be seen from the figure, the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within +/-5 mu m, which shows that the optical lens can excellently correct the chromatic aberration of the marginal field of view and the secondary spectrum of the whole image surface.
Please refer to table 5, which shows the corresponding optical characteristics of the above embodiments, including the effective focal length f, the total optical length TTL, the f-stop FNO, the real image height IH, the maximum field angle FOV, the chief ray image plane incident angle CRA, and the values corresponding to each conditional expression in each embodiment.
TABLE 5
In summary, the optical lens according to the embodiments of the present invention achieves the effects of a large field angle, a large aperture, a high definition, and a high imaging quality by reasonably matching the lens shapes and focal power combinations among the lenses.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above embodiments only show several embodiments of the present invention, and the description is specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (10)
1. An optical lens system includes three groups of lenses, which are sequentially disposed along an optical axis from an object side to an image plane:
the first lens group with negative focal power sequentially comprises: a first lens having a negative refractive power, an image-side surface of which is concave; a second lens with negative focal power, wherein the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a convex surface;
a diaphragm;
the second lens group with positive focal power sequentially comprises: the image side surface of the third lens is a convex surface; a fourth lens having a positive refractive power, both the object-side surface and the image-side surface of the fourth lens being convex;
the third lens group with positive focal power sequentially comprises: a fifth lens having a negative refractive power, an image-side surface of which is concave; a sixth lens element having a positive refractive power, the object-side surface and the image-side surface of the sixth lens element being convex; a seventh lens element with a focal power, wherein the object-side surface of the seventh lens element is concave and the image-side surface of the seventh lens element is convex; an eighth lens element having a refractive power, the object-side surface of the eighth lens element being convex and the image-side surface of the eighth lens element being concave;
the effective focal length f of the optical lens and the real image height IH corresponding to the maximum field angle satisfy that: IH/f is more than 1.6 and less than 1.8.
2. An optical lens according to claim 1, wherein the total optical length TTL and the effective focal length f satisfy: TTL/f is more than 4.0 and less than 5.0.
3. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f of the fifth lens 5 Satisfies the following conditions: -2.0 < f 5 /f＜0。
4. An optical lens according to claim 1, characterized in that the optical back focus BFL and the effective focal length f of the optical lens satisfy: BFL/f is more than 0.4 and less than 0.7.
5. An optical lens as claimed in claim 1, characterized in that the maximum field angle FOV of the optical lens, the object-side effective working aperture D of the first lens 1 And the real image height IH corresponding to the maximum field angle satisfies the following conditions: d is more than 0.55 1 /IH/tan(FOV/2)＜0.65。
6. An optical lens according to claim 1, characterized in that the focal length f of the first lens group G1 Focal length f of the second lens group G2 Satisfies the following conditions: -1.3 < f G1 /f G2 ＜0.7。
7. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f of the third lens group G3 Satisfies the following conditions: f is more than 5.0 G3 /f＜10.0。
8. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f of the seventh lens 7 Satisfies the following conditions: 2.0 < | f 7 /f|。
9. An optical lens according to claim 1, characterized in that the effective focal length f of the optical lens and the focal length f of the eighth lens 8 Satisfies the following conditions: 2.5 < | f 8 /f|。
10. An optical lens according to claim 1, wherein a total optical length TTL of the optical lens and a sum Σ CT of central thicknesses of the first lens to the eighth lens along an optical axis, respectively, satisfy: 0.5 <. Sigma CT/TTL < 0.8.
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