CN111708158B - Wide-angle lens and imaging apparatus - Google Patents
Wide-angle lens and imaging apparatus Download PDFInfo
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- CN111708158B CN111708158B CN202010840115.7A CN202010840115A CN111708158B CN 111708158 B CN111708158 B CN 111708158B CN 202010840115 A CN202010840115 A CN 202010840115A CN 111708158 B CN111708158 B CN 111708158B
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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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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
- G02B1/041—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
- G02B13/001—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
- G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
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Abstract
The present invention provides a wide-angle lens, including: the first lens with negative focal power has a convex object-side surface and a concave image-side surface; the image side surface of the second lens is a concave surface; a third lens with positive focal power, wherein the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a convex surface; a diaphragm; the fourth lens with positive focal power has a convex object-side surface and a convex image-side surface; a fifth lens element with negative refractive power, the object-side surface of which is concave and the image-side surface of which is concave; the sixth lens with positive focal power has a convex object-side surface and a convex image-side surface; a seventh lens element with positive refractive power having a convex object-side surface and a convex image-side surface; an optical filter; the fourth lens and the fifth lens form a bonding body. The first lens and the third lens are glass lenses, and the other lenses are plastic aspheric lenses. The wide-angle lens provided by the invention at least has the characteristics of good thermal stability, light weight, small volume, high imaging quality and the like. The invention also provides an imaging device.
Description
Technical Field
The present disclosure relates to optical lenses, and particularly to a wide-angle lens and an imaging device.
Background
With the performance improvement and size reduction of common photosensitive elements such as a photosensitive coupling element (CCD) or a Complementary Metal Oxide Semiconductor (CMOS), the performance improvement and size reduction of the photosensitive elements are realized, and thus higher requirements are provided for high imaging quality and miniaturization of a matched lens.
In recent years, with the explosive development of the automatic driving technology, the automobile industry is undergoing an unprecedented great revolution, and the vehicular lens is also facing a rapid development as a key component of the automatic driving assistance system. In some occasions, because the use environment of the automobile is often cold and hot alternated, the imaging lens is required to have good thermal stability, and the glass material with stable thermal expansion coefficient is used completely, so that the manufacturing cost is high and the market competitiveness is poor; meanwhile, in order to reduce chromatic aberration, a glass spherical lens is often used for bonding in the lens to form a glass bonding body, but the weight of the glass bonding body is large, the size of the lens is also often large in consideration of a glass processing technology, and the miniaturization and the light weight of the lens are not facilitated.
Disclosure of Invention
In order to solve the above problems, the present invention provides a wide-angle lens and an imaging device, which have at least the characteristics of good thermal stability, light weight, small volume, high imaging quality, and the like.
In a first aspect, an embodiment of the present invention provides a wide-angle lens, which includes, in order from an object side to an image plane along an optical axis, a first lens element, a second lens element, a third lens element, a stop, a fourth lens element, a fifth lens element, a sixth lens element, a seventh lens element, and an optical filter; the first lens has negative focal power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; the second lens has negative focal power, the object side surface of the second lens is a convex surface or a concave surface, and the image side surface of the second lens is a concave surface; the third lens has positive focal power, and both the object side surface and the image side surface of the third lens are convex surfaces; the fourth lens has positive focal power, and both the object side surface and the image side surface of the fourth lens are convex surfaces; the fifth lens has negative focal power, the object side surface and the image side surface of the fifth lens are both concave surfaces, and the fourth lens and the fifth lens form a plastic aspheric surface adhesive body; the sixth lens has positive focal power, and both the object side surface and the image side surface of the sixth lens are convex surfaces; the seventh lens has positive focal power, and both the object side surface and the image side surface of the seventh lens are convex surfaces; wherein, first lens and third lens are glass sphere lens, and second lens, fourth lens, fifth lens, sixth lens and seventh lens are plastic aspheric lens, and wide-angle lens satisfies the conditional expression: 0.01/° < D/h/FOV < 0.02/°; where FOV represents the maximum angle of view of the wide-angle lens, D represents the maximum aperture of the object-side surface of the first lens, and h represents the actual image height corresponding to the maximum angle of view of the wide-angle lens.
In a second aspect, embodiments of the present invention further provide an imaging apparatus, including the wide-angle lens described above, and an imaging element configured to convert an optical image formed by the wide-angle lens into an electrical signal.
Compared with the prior art, the wide-angle lens provided by the invention adopts the matching of seven glass-plastic mixed lenses, and has good thermal stability and can realize clear imaging through reasonable control of various surface types and reasonable combination of materials and focal power. The light is incident from the object side surface of the first lens, the object side surface of the first lens needs to be enlarged in order to realize the wide-angle characteristic, but the volume of the lens is larger, the conditional expression of 0.01/° < D/h/FOV < 0.02/°ismet, the small caliber at the front end of the lens can be realized by reasonably controlling the D value, and the small volume of the lens is ensured while the wide angle of view of the lens is realized. The imaging requirements of good thermal stability and high pixel can be met while the miniaturization is realized. The lens adopts a plastic aspheric surface adhesive body, effectively reduces aberration such as chromatic aberration and the like, and has the advantages of light weight, small volume, low cost and the like compared with a conventional glass spherical surface adhesive body. Meanwhile, after the plastic aspheric adhesive body is abutted against the diaphragm, the characteristic that light beams near the diaphragm are concentrated is utilized, the aperture of the adhesive body is effectively reduced while aberration correction such as chromatic aberration is realized, and the weight and the manufacturing cost of the lens are further reduced.
The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
Drawings
Fig. 1 is a schematic structural diagram of a wide-angle lens in a first embodiment of the present application;
FIG. 2 is a field curvature diagram of a wide-angle lens according to a first embodiment of the present application;
FIG. 3 is a MTF chart of a wide-angle lens according to a first embodiment of the present application;
FIG. 4 is a diagram of axial chromatic aberration of a wide-angle lens according to a first embodiment of the present application;
FIG. 5 is a schematic structural diagram of a wide-angle lens in a second embodiment of the present application;
FIG. 6 is a field curvature diagram of a wide-angle lens according to a second embodiment of the present application;
FIG. 7 is a MTF graph of a wide-angle lens according to a second embodiment of the present application;
FIG. 8 is a diagram of axial chromatic aberration of a wide-angle lens in a second embodiment of the present application;
fig. 9 is a schematic structural diagram of a wide-angle lens in a third embodiment of the present application;
FIG. 10 is a field curvature diagram of a wide-angle lens according to a third embodiment of the present application;
FIG. 11 is an MTF chart of a wide-angle lens according to a third embodiment of the present application;
FIG. 12 is a diagram of axial chromatic aberration of a wide-angle lens according to a third embodiment of the present application;
fig. 13 is a schematic structural diagram of a wide-angle lens in a fourth embodiment of the present application;
FIG. 14 is a field curvature diagram of a wide-angle lens according to a fourth embodiment of the present application;
FIG. 15 is an MTF chart of a wide-angle lens in a fourth embodiment of the present application;
FIG. 16 is a diagram illustrating axial chromatic aberration of a wide-angle lens according to a fourth embodiment of the present application;
fig. 17 is a schematic configuration diagram of an image forming apparatus provided in a fifth embodiment of the present invention.
Detailed Description
In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
An embodiment of the present invention provides a wide-angle lens, which includes, in order from an object side to an image plane along an optical axis, a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an optical filter. The first lens has negative focal power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; the second lens has negative focal power, the object side surface of the second lens is a convex surface or a concave surface, and the image side surface of the second lens is a concave surface; the third lens has positive focal power, and both the object side surface and the image side surface of the third lens are convex surfaces; the fourth lens has positive focal power, and both the object side surface and the image side surface of the fourth lens are convex surfaces; the fifth lens has negative focal power, the object side surface and the image side surface of the fifth lens are both concave surfaces, and the fourth lens and the fifth lens form a plastic aspheric surface adhesive body; the sixth lens has positive focal power, and both the object side surface and the image side surface of the sixth lens are convex surfaces; the seventh lens has positive focal power, and both the object side surface and the image side surface of the seventh lens are convex surfaces; the first lens and the third lens are both glass spherical lenses, the second lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all plastic aspheric lenses, and the optical centers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all positioned on the same straight line; the wide-angle lens satisfies the conditional expression: 0.01/° < D/h/FOV < 0.02/°; where FOV represents the maximum angle of view of the wide-angle lens, D represents the maximum aperture of the object-side surface of the first lens, and h represents the actual image height corresponding to the maximum angle of view of the wide-angle lens.
The light is incident from the object side surface of the first lens, the object side surface of the first lens needs to be enlarged in order to realize the wide-angle characteristic, but the volume of the lens is larger, the conditional expression of 0.01/° < D/h/FOV < 0.02/°ismet, the small caliber at the front end of the lens can be realized by reasonably controlling the D value, and the small volume of the lens is ensured while the wide angle of the lens is realized; the lens adopts the plastic aspheric surface adhesive body, effectively reduces aberration such as chromatic aberration and the like, and has the advantages of light weight, small volume, low cost and the like compared with the conventional glass spherical surface adhesive body. Meanwhile, after the plastic aspheric adhesive body is abutted against the diaphragm, the aperture of the adhesive body is effectively reduced while aberration correction such as chromatic aberration and the like is realized by utilizing the characteristic that light beams near the diaphragm are concentrated, and the weight and the manufacturing cost of the lens are further reduced; the optical filter is arranged between the seventh lens and the imaging surface and can be used for selectively filtering part of light so as to optimize the imaging result.
Further, in some embodiments, the wide-angle lens satisfies the conditional expression:
1.5＜Imgh/f＜1.9； （1）
where, Imgh represents a half of the diagonal length of the effective pixel area on the imaging surface of the wide-angle lens, and f represents the focal length of the wide-angle lens. Satisfying the conditional expression (1), the imaging of the photosensitive element to a large object side space can be realized, which is advantageous for realizing a wide angle.
Further, in some embodiments, the wide-angle lens satisfies the conditional expression:
0.017/°＜TTL/h/FOV＜0.023/°； （2）
wherein, TTL represents the total optical length of the wide-angle lens, FOV represents the maximum field angle of the wide-angle lens, and h represents the image height corresponding to the maximum field angle of the wide-angle lens. Satisfying the conditional expression (2), the miniaturization of the lens can be realized, and the optical total length of the lens under the same imaging surface with the same field angle is ensured to be shorter.
Further, in some embodiments, the wide-angle lens satisfies the conditional expression:
-2.2＜f2/f＜-1.9； （3）
-0.9＜f2/f3＜-0.7； （4）
where f2 denotes a focal length of the second lens, f3 denotes a focal length of the third lens, and f denotes a focal length of the wide-angle lens. Because the second lens is a concave lens, the second lens has a divergent effect on light, the included angle between marginal light and an optical axis can be reduced, conditional expressions (3) and (4) are satisfied, the focal length of the second lens in the whole system can be reasonably controlled to account for the ratio, the deflection angle of the light is effectively reduced, and the optical aberration can be reduced by matching with a subsequent lens.
Further, in some embodiments, the wide-angle lens satisfies the conditional expression:
0.33＜(T23+T45)/T17＜0.4； （5）
2.0＜T23/T45＜3.5； （6）
where T23 denotes an air space on the optical axis between the first lens and the second lens, T45 denotes an air space on the optical axis between the second lens and the third lens, and T17 denotes an air space on the optical axis between the first lens and the stop. The requirements of conditional expressions (5) and (6) are favorable for reasonably distributing the lens distance at the front end of the wide-angle lens, so that the whole system can meet the wide-angle characteristic and realize miniaturization.
Further, in some embodiments, the wide-angle lens satisfies the conditional expression:
2.6＜E4/C4+E5/C5＜2.9； （7）
where E4 denotes an edge thickness of the fourth lens, E5 denotes an edge thickness of the fifth lens, C4 denotes a center thickness of the fourth lens, and C5 denotes a center thickness of the fifth lens. The fourth lens and the fifth lens form the plastic aspheric adhesive lens, the conditional expression (7) is satisfied, the manufacturing difficulty can be reduced and the adhesive yield of the plastic lens can be increased by reasonably distributing the ratio of the center thickness to the edge thickness of the fourth lens and the fifth lens.
Further, in some embodiments, the wide-angle lens satisfies the conditional expression:
-15mm-1＜(V4+V5)(φ4+φ5)＜-11mm-1； （8）
39mm-1＜(V6+V7)(φ6+φ7)＜42mm-1； （9）
where V4 denotes an abbe number of the fourth lens, V5 denotes an abbe number of the fifth lens, V6 denotes an abbe number of the sixth lens, V7 denotes an abbe number of the seventh lens, Φ 4 denotes an optical power of the fourth lens, Φ 5 denotes an optical power of the fifth lens, Φ 6 denotes an optical power of the sixth lens, and Φ 7 denotes an optical power of the seventh lens. The chromatic aberration of the system can be well corrected and the imaging quality can be improved by reasonably distributing and balancing the dispersion relation among the lenses according to the conditional expressions (8) and (9).
Further, in some embodiments, the wide-angle lens satisfies the conditional expression:
0.5＜ƩCT/TTL＜0.65； （10）
wherein Ʃ CT represents the total thickness of the first lens element to the seventh lens element, and TTL represents the total optical length of the wide-angle lens. Satisfying the conditional expression (10), the total thickness of the centers of the lenses can be reasonably configured, the total optical length of the lens can be effectively shortened, and the miniaturization and the wide angle of the lens can be realized.
Further, in some embodiments, the wide-angle lens satisfies the conditional expression:
0.15＜BFL/TTL＜0.19； （11）
the BFL represents a distance between an image side surface of the seventh lens and an imaging surface of the wide-angle lens on an optical axis, and the TTL represents an optical total length of the wide-angle lens. Satisfy conditional expression (11), the back focal distance of camera lens can reasonable control, reduce the structural interference of camera lens body and imaging chip, be favorable to the installation of camera lens to be used.
Further, in some embodiments, the wide-angle lens has an f-number less than 2.1, which can meet the requirements of a dark environment.
The surface shapes of the aspheric lens in the wide-angle lens provided by the invention all satisfy the following equations:
wherein z represents the distance between the curved surface and the vertex of the curved surface in the optical axis direction, c represents the curvature of the vertex of the curved surface, K represents a conic coefficient, h represents the distance between the optical axis and the curved surface, and B, C, D, E, F, G, H represents the curved surface coefficients of fourth order, sixth order, eighth order, tenth order, twelfth order, fourteenth order and sixteenth order, respectively.
In the following embodiments, the thickness, the radius of curvature, and the material selection of each lens in the wide-angle lens are different, and specific differences can be referred to in the parameter tables of the embodiments.
First embodiment
Referring to fig. 1, a schematic structural diagram of a wide-angle lens 100 according to an embodiment of the present invention includes, in order from an object side to an image plane along an optical axis: a first lens L1, a second lens L2, a third lens L3, a stop ST, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and a filter G1.
The first lens element L1 has negative power, and has a convex object-side surface S1 and a concave image-side surface S2;
the second lens element L2 has negative power, and has a convex object-side surface S3 and a concave image-side surface S4;
the third lens L3 has positive power, and both the object-side surface S5 and the image-side surface S6 are convex;
the fourth lens L4 has positive power, and both the object-side surface S7 and the image-side surface S8-1 are convex;
the fifth lens L5 has negative focal power, the object-side surface S8-2 and the image-side surface S9 of the fifth lens L5 are both concave, and the fourth lens L4 and the fifth lens L5 form a plastic aspheric adhesive body, specifically, the image-side surface S8-1 of the fourth lens L4 and the object-side surface S8-2 of the fifth lens L5 are bonded integrally, that is, the image-side surface S8-1 of the fourth lens L4 and the object-side surface S8-2 of the fifth lens L5 are bonded seamlessly, and the bonding surface is S8;
the sixth lens L6 has positive power, and both the object-side surface S10 and the image-side surface S11 are convex;
the seventh lens L7 has positive power, and both the object-side surface S12 and the image-side surface S13 are convex;
the stop ST is disposed between the third lens L3 and the fourth lens L4.
The filter G1 is disposed between the seventh lens L7 and the imaging surface S16, and the filter G1 can be used to selectively filter part of the light, so as to optimize the imaging result. In this embodiment, the imaging surface S16 may be a plane where light incident from the object side is imaged on the image side by the wide-angle lens 100.
The first lens L1 and the third lens L3 in the wide-angle lens 100 are both glass spherical lenses; the second lens L2, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are all plastic aspheric lenses, and optical centers of the first lens L2, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are all located on the same straight line.
The parameters related to each lens in the wide-angle lens 100 provided in this embodiment are shown in table 1.
TABLE 1
The surface type coefficients of the respective aspherical surfaces of the second lens L2, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 in the wide-angle lens 100 in the present embodiment are shown in table 2.
TABLE 2
As shown in fig. 2, fig. 3 and fig. 4, the field curvature diagram, the MTF diagram and the axial chromatic aberration diagram of the wide-angle lens 100 provided in this embodiment are respectively shown, and as can be seen from fig. 2, the field curvature of the wide-angle lens 100 in this embodiment is entirely within a range of-0.1 mm to 0.1mm, which indicates that the field curvature is well corrected, and the wide-angle lens 100 has a high field curvature performance; as can be seen from fig. 3, the MTF curve of the wide-angle lens 100 uniformly decreases from 0 ° to 90 °, and the overall resolution of the lens at 60lp/mm is greater than 0.5, which indicates that the wide-angle lens 100 has good resolution and good image resolution performance; as can be seen from FIG. 4, the overall chromatic aberration is in the range of-0.06 mm to 0.06mm, which indicates that the wide-angle lens 100 has good achromatic performance.
Second embodiment
Referring to fig. 5, a schematic structural diagram of a wide-angle lens 200 according to an embodiment of the present invention is shown, where the structure of the wide-angle lens 200 in the embodiment is substantially the same as that of the wide-angle lens 100 in the first embodiment, and the difference is that: the object side surface S3 of the second lens is concave, and the relevant parameters and air space of each lens of the lens are different.
Table 3 shows the lens-related parameters of wide-angle lens 200 according to the present embodiment.
TABLE 3
The surface shape coefficients of the aspherical surfaces in wide-angle lens 200 in the present embodiment are shown in table 4.
TABLE 4
In the present embodiment, the field curvature diagram, the MTF diagram and the axial chromatic aberration diagram of the wide-angle lens 200 are respectively shown in fig. 6, fig. 7 and fig. 8, and it can be seen from fig. 6 that the field curvature of the wide-angle lens 200 is entirely within a range of-0.05 mm to 0.05mm, which indicates that the field curvature is well corrected, and the wide-angle lens 200 has a high field curvature performance; as can be seen from fig. 7, the MTF curve of the wide-angle lens 200 decreases uniformly from 0 ° to 90 °, and the overall resolution of the lens at 60lp/mm is greater than 0.6, which indicates that the wide-angle lens 200 has good resolution performance; as can be seen from fig. 8, the total chromatic aberration of the wide-angle lens 200 is in the range of-0.04 mm to 0.04mm, which indicates that the wide-angle lens 200 has good achromatic performance.
Third embodiment
Referring to fig. 9, a schematic structural diagram of a wide-angle lens 300 according to an embodiment of the present invention is shown, where the structure of the wide-angle lens 300 in the embodiment is substantially the same as that of the wide-angle lens 100 in the first embodiment, and the difference is that: the relevant parameters and air intervals of the lenses of the lens are different.
The parameters related to each lens of the wide-angle lens 300 provided in the present embodiment are shown in table 5.
TABLE 5
The surface shape coefficients of the aspherical surfaces in the wide-angle lens 300 in the present embodiment are shown in table 6.
TABLE 6
In the present embodiment, the field curvature diagram, the MTF diagram and the axial chromatic aberration diagram of the wide-angle lens 300 are respectively shown in fig. 10, fig. 11 and fig. 12, and as can be seen from fig. 10, the field curvature of the wide-angle lens 300 is entirely within a range of-0.1 mm to 0.1mm, which indicates that the field curvature is well corrected, and the wide-angle lens 300 has a high field curvature performance; as can be seen from fig. 11, the MTF curve of the wide-angle lens 300 uniformly decreases from 0 ° to 90 °, and the overall resolution of the lens at 60lp/mm is greater than 0.5, which indicates that the wide-angle lens 300 has good resolution performance; as can be seen from FIG. 12, the total chromatic aberration of the wide-angle lens 300 is in the range of-0.1 mm to 0.1mm, which indicates that the wide-angle lens 300 has good achromatic performance.
Fourth embodiment
Referring to fig. 13, a schematic structural diagram of a wide-angle lens 400 according to an embodiment of the present invention is shown, where the structure of the wide-angle lens 400 in the embodiment is substantially the same as that of the wide-angle lens 100 in the first embodiment, and the difference is that: the object side surface S3 of the second lens is concave, and the relevant parameters and air space of each lens of the lens are different.
The parameters related to each lens in the wide-angle lens 400 provided in the present embodiment are shown in table 7.
TABLE 7
The surface shape coefficients of the aspherical surfaces in the wide-angle lens 400 in the present embodiment are shown in table 8.
TABLE 8
In the present embodiment, the field curvature diagram, the MTF diagram, and the axial chromatic aberration diagram of the wide-angle lens 400 are respectively shown in fig. 14, fig. 15, and fig. 16, and it can be seen from fig. 14 that the field curvature is entirely within a range of-0.05 to 0.05mm, which indicates that the field curvature is well corrected, and the wide-angle lens 400 has a high field curvature performance; as can be seen from fig. 15, the overall resolution of the lens is greater than 0.6 when the MTF curve of the wide-angle lens 400 is 60lp/mm, which indicates that the wide-angle lens 400 has good resolution performance; as can be seen from fig. 16, the total chromatic aberration of the wide-angle lens 400 is in the range of-0.04 mm to 0.04mm, which indicates that the wide-angle lens 400 has good achromatic performance.
Table 9 shows the four embodiments and their corresponding optical characteristics, which mainly include the focal length F, F-number F/NO, field angle FOV and total optical length TTL of the wide-angle lens, and the values corresponding to each of the foregoing conditional expressions.
TABLE 9
In summary, the wide-angle lens provided by the embodiment of the invention has at least the following advantages:
(1) the first lens and the third lens in the wide-angle lens provided by the embodiment of the invention are both glass lenses; the second lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all plastic aspheric lenses, and the aberration of the lens is effectively corrected by optimally configuring the positive and negative refractive indexes of each lens.
(2) First lens and third lens all adopt the lens of glass material, and other lenses adopt the plastic material, through glass and the reasonable collocation of plastic material, make the camera lens have good thermal stability, can be applicable to the demand in fields harsher to the environment, for example fields such as on-vehicle, unmanned aerial vehicle, control.
(3) The wide-angle lens provided by the embodiment of the invention adopts the plastic aspheric lens, so that the aberration of the lens can be effectively corrected, and the resolving power of the whole lens group is improved. Particularly, the fourth lens and the fifth lens form a plastic aspheric surface adhesive body, so that aberration such as chromatic aberration is effectively reduced, and compared with a conventional glass spherical surface adhesive body, the wide-angle lens has the advantages of light weight, small volume and low cost, and the market competitiveness of the product is greatly improved.
(4) The plastic aspheric adhesive body in the wide-angle lens provided by the embodiment of the invention is arranged on one side of the diaphragm, which is far away from the object side, so that the aperture of the adhesive body is effectively reduced, and the weight and the manufacturing cost of the lens are further reduced.
(5) In order to realize the wide-angle characteristic, the object side surface of the first lens needs to be enlarged, but the lens volume is large, and the conditional expression is satisfied: D/h/FOV is more than 0.01 and less than 0.02; through reasonable control D value, can realize the small-bore of camera lens front end, guarantee that the camera lens has less volume when realizing the wide visual angle of camera lens.
In summary, the wide-angle lens provided by the embodiment of the invention adopts a combination of seven glass-plastic mixed lenses, and by reasonably distributing the focal power, the surface type, the central thickness of each lens, the on-axis distance between each lens and the like, the lens has the beneficial effects of miniaturization, light weight, good thermal stability, good processability and the like while realizing good imaging quality.
Fifth embodiment
Referring to fig. 17, a schematic structural diagram of an imaging device 500 according to the present embodiment includes a wide-angle lens (e.g., the wide-angle lens 100) and an imaging element 510 in any of the embodiments. The imaging element 510 may be a CMOS (Complementary Metal Oxide Semiconductor) image sensor, and may also be a CCD (Charge Coupled Device) image sensor.
The imaging device 500 may be a vehicle monitor, a drone, a panoramic camera, and any other electronic device with a wide-angle lens.
The imaging device 500 provided by the embodiment includes the wide-angle lens in any of the above embodiments, and since the wide-angle lens has the characteristics of good thermal stability, light weight, small volume, clear imaging and the like, the imaging device 500 can clearly image, is light and has the advantages of better thermal stability and the like.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (9)
1. A wide-angle lens, which is composed of a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens, a seventh lens and a filter in sequence from an object side to an image plane along an optical axis,
the first lens has negative focal power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface;
the second lens has negative focal power, the object side surface of the second lens is a convex surface or a concave surface, and the image side surface of the second lens is a concave surface;
the third lens has positive focal power, and both the object-side surface and the image-side surface of the third lens are convex surfaces;
the fourth lens has positive focal power, and both the object-side surface and the image-side surface of the fourth lens are convex surfaces;
the fifth lens has negative focal power, both the object side surface of the fifth lens and the image side surface of the fifth lens are concave surfaces, and the fourth lens and the fifth lens form a plastic aspheric surface adhesive body;
the sixth lens has positive focal power, and both the object side surface and the image side surface of the sixth lens are convex surfaces;
the seventh lens has positive focal power, and both the object side surface and the image side surface of the seventh lens are convex surfaces;
wherein, first lens with the third lens are glass sphere lens, the second lens fourth lens fifth lens sixth lens with the seventh lens are plastic aspheric lens, wide-angle lens satisfies the conditional expression:
0.01/°＜D/h/FOV＜0.02/°；
2.6＜E4/C4+E5/C5＜2.9；
wherein FOV represents the maximum field angle of the wide-angle lens, D represents the maximum clear aperture of the object-side surface of the first lens, h represents the actual image height corresponding to the maximum field angle of the wide-angle lens, E4 represents the edge thickness of the fourth lens, E5 represents the edge thickness of the fifth lens, C4 represents the center thickness of the fourth lens, and C5 represents the center thickness of the fifth lens.
2. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:
1.5＜Imgh/f＜1.9；
wherein, Imgh represents a half of a diagonal length of an effective pixel area on an imaging surface of the wide-angle lens, and f represents a focal length of the wide-angle lens.
3. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:
0.017/°＜TTL/h/FOV＜0.023/°；
wherein, TTL represents the total optical length of the wide-angle lens.
4. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:
-2.2＜f2/f＜-1.9；
-0.9＜f2/f3＜-0.7；
where f2 denotes a focal length of the second lens, f3 denotes a focal length of the third lens, and f denotes a focal length of the wide-angle lens.
5. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:
0.33＜(T23+T45)/T17＜0.4；
2.0＜T23/T45＜3.5；
wherein T23 denotes an air space on the optical axis between the first lens and the second lens, T45 denotes an air space on the optical axis between the second lens and the third lens, and T17 denotes an air space on the optical axis between the first lens and the stop.
6. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:
-15mm-1＜(V4+V5)(φ4+φ5)＜-11mm-1；
39mm-1＜(V6+V7)(φ6+φ7)＜42mm-1；
wherein V4 denotes an abbe number of the fourth lens, V5 denotes an abbe number of the fifth lens, V6 denotes an abbe number of the sixth lens, V7 denotes an abbe number of the seventh lens, φ 4 denotes an optical power of the fourth lens, φ 5 denotes an optical power of the fifth lens, φ 6 denotes an optical power of the sixth lens, φ 7 denotes an optical power of the seventh lens.
7. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:
0.5＜ƩCT/TTL＜0.65；
Ʃ CT represents the sum of the central thicknesses of the first lens element to the seventh lens element on the optical axis, and TTL represents the total optical length of the wide-angle lens.
8. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:
0.15＜BFL/TTL＜0.19；
and BFL represents the distance between the image side surface of the seventh lens and the imaging surface on the optical axis, and TTL represents the total optical length of the wide-angle lens.
9. An imaging apparatus comprising the wide-angle lens according to any one of claims 1 to 8, and an imaging element for converting an optical image formed by the wide-angle lens into an electrical signal.
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