Disclosure of Invention
In view of the above, the present invention provides a two-lens small-diameter large-field-angle lens, which can not only capture images in a narrow space, but also satisfy the requirements of small outer diameter and large field angle.
In order to achieve the purpose, the invention provides the following technical scheme:
the lens with two lenses, small diameter and large field angle is characterized in that the lens is sequentially provided with the following components from an object side to an image side along an optical axis: a first lens (L1), an aperture Stop (Stop), and a second lens (L2); wherein the first lens (L1) is a negative lens having a first surface and a second surface whose central position is concave to the image side; the second lens (L2) is a positive lens having a third surface and a fourth surface convex to the image side; the aperture Stop (Stop) is positioned between the first lens (L1) and the second lens (L2) and is used for balancing the outer diameter of the two lenses.
Preferably, in the above two-lens small-diameter large-field-angle lens, the surfaces of the first lens (L1) and the second lens (L2) are spherical or aspherical.
Preferably, in the two-lens small-diameter large-angle lens described above, an optical filter (IR) is provided on the image side of the second lens (L2).
Preferably, in the above two-lens small-diameter large-field-angle lens, the lens satisfies the following conditions: 0.1< (Tfs/f)/tan (hfov) < 0.5; wherein, Tfs is: the distance from the center of the object space surface of the first lens (L1) to the aperture Stop (Stop); f is the effective focal length of the lens; the HFOV is half of the maximum field angle.
Preferably, in the above two-lens small-diameter large-field-angle lens, the lens satisfies the following conditions: 1< f/f2< 2; wherein f is the effective focal length of the lens; f2 is the focal length of the second lens.
Preferably, in the above two-lens small-diameter large-field-angle lens, the lens satisfies the following conditions: 0.1< [ Ho/tan (HFOV) ]/f < 0.5; the Ho is the height of the light at the edge of the object space surface of the first lens when the maximum field angle is achieved; HFOV is half of the maximum field angle; f is the effective focal length of the lens.
According to the technical scheme, compared with the prior art, the invention has the following characteristics:
a first lens (L1) which is a negative lens and is beneficial to realizing a large field angle;
the aperture diaphragm (Stop) is positioned between the two lenses, and the outer diameters of the two lenses are balanced, so that the requirement of small outer diameter of the lens is favorably met;
the second lens (L2) is a positive lens, and the focal power required by the lens for imaging is mainly provided by the second lens;
the invention adopts two lenses, can shoot in narrow space, meets the size requirement of small outer diameter of the lens and the function of large field angle, and can be used in the field of narrow shooting space or narrow installation space of the lens.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic diagram of the present invention.
Fig. 2 is a schematic structural diagram of embodiment 1 of the present invention.
FIG. 3 is a light ray fan diagram of embodiment 1 of the present invention.
FIG. 4 is a graph showing curvature of field and distortion in example 1 of the present invention.
Fig. 5 is a graph showing MTF resolution in embodiment 1 of the present invention.
Fig. 6 is a schematic structural diagram of embodiment 2 of the present invention.
FIG. 7 is a light ray fan diagram according to example 2 of the present invention.
Fig. 8 is a graph showing curvature of field and distortion in example 2 of the present invention.
Fig. 9 is a graph showing MTF resolution in embodiment 2 of the present invention.
Fig. 10 is a schematic structural diagram of embodiment 3 of the present invention.
FIG. 11 is a light ray fan diagram of embodiment 3 of the present invention.
FIG. 12 is a graph showing curvature of field and distortion in example 3 of the present invention.
FIG. 13 is a graph showing MTF resolution in embodiment 3 of the present invention
FIG. 14 is a schematic structural diagram of embodiment 4 of the present invention.
Figure 15 is a ray fan diagram of embodiment 4 of the present invention.
FIG. 16 is a graph showing curvature of field and distortion in example 4 of the present invention.
FIG. 17 is a graph showing MTF resolution in embodiment 4 of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, 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 invention.
Example 1: fig. 2 is a schematic view of an optical lens according to a first embodiment of the invention. As shown in fig. 2 to 5, the first lens L1, the aperture Stop, the second lens L2, the optical filter (IR), and the Image plane Image are disposed in this order from the object side to the Image side along the optical axis according to the first embodiment of the present invention; a first lens L1 having a first surface S1 and a second surface S2 whose central position is concave to the image side; the aperture Stop has a surface S3; a second lens L2 having a third surface S4 and a fourth surface S5 convex to the image side; the filter IR has a first surface S6 facing the object side and a second surface S7 facing the image side; the Image plane Image has a surface S8.
Lens data of the above-described lens are shown in tables 1 and 2 below.
[ TABLE 1 ]
[ TABLE 2 ]
The conditions satisfied by the above-described lens are shown in table 3.
[ TABLE 3 ]
Marking
|
Content of the presentation
|
Numerical value
|
f
|
Effective focal length of lens
|
1.469
|
HFOV
|
Half of maximum field angle
|
70
|
f1
|
Focal length of the first lens (L1)
|
-1.638
|
f2
|
Focal point of the second lens (L2)Distance between
|
1.17
|
Ho
|
The first lens (L1) object side surface edge ray height at maximum field angle.
|
0.782
|
Tfs
|
The distance from the center of the object space surface of the first lens (L1) to the aperture Stop (Stop)
|
0.907
|
|
|
|
2、
|
0.1<(Tfs/f)/tan(HFOV)<0.5
|
0.225
|
3、
|
1<f/f2<2
|
1.256
|
4、
|
0.1<[Ho/tan(HFOV)]/f<0.5
|
0.194 |
In the above embodiment:
as shown in fig. 3 (light sector), it can be seen that the spherical aberration of the lower order has been corrected well and the spherical aberration of the higher order is smaller.
As shown in fig. 4 (field curvature and distortion diagram), the distortion curve is relatively smooth, which effectively improves the definition of the expanded image.
As shown in fig. 5 (MTF resolution graph), it can be seen from the curves that MTF curves of the meridian and the sagittal of each field of view are relatively close, which indicates that the lens has relatively good imaging consistency in both directions of the meridian (T) and the sagittal (S), and the lens has relatively good imaging effect and resolution.
Example 2:
fig. 5 is a schematic view of an optical lens according to a second embodiment of the present invention. As shown in fig. 6 to 9, the first lens L1, the aperture Stop, the second lens L2, the optical filter (IR), and the Image plane Image are disposed in this order from the object side to the Image side along the optical axis according to the second embodiment of the present invention; a first lens L1 having a first surface S1 and a second surface S2 whose central position is concave to the image side; the aperture Stop has a surface S3; a second lens L2 having a third surface S4 and a fourth surface S5 convex to the image side; the filter IR has a first surface S6 facing the object side and a second surface S7 facing the image side; the Image plane Image has a surface S8.
Lens data of the above lenses are shown in table 4 below.
[ TABLE 4 ]
The conditions satisfied by the above-described lens are shown in table 5.
[ TABLE 5 ]
Marking
|
Content of the presentation
|
Numerical value
|
f
|
Effective focal length of lens
|
1.008
|
HFOV
|
Half of maximum field angle
|
60
|
f1
|
Focal length of the first lens (L1)
|
-2.27
|
f2
|
Focal length of the second lens (L2)
|
0.806
|
Ho
|
The first lens (L1) object side surface edge ray height at maximum field angle.
|
0.392
|
Tfs
|
The distance from the center of the object space surface of the first lens (L1) to the aperture Stop (Stop)
|
0.365
|
|
|
|
2、
|
0.1<(Tfs/f)/tan(HFOV)<0.5
|
0.209
|
3、
|
1<f/f2<2
|
1.251
|
4、
|
0.1<[Ho/tan(HFOV)]/f<0.5
|
0.225 |
In the above embodiment:
as shown in fig. 7 (light sector), it can be seen that the spherical aberration of the lower order has been corrected well and the spherical aberration of the higher order is smaller.
As shown in fig. 8 (field curvature and distortion diagram), the distortion curve is relatively smooth, which effectively improves the definition of the expanded image.
As shown in fig. 9 (MTF resolution graph), it can be seen from the curves that MTF curves of the meridian and the sagittal of each field of view are relatively close, which indicates that the lens has relatively good imaging consistency in both directions of the meridian (T) and the sagittal (S), and the lens has relatively good imaging effect and resolution.
Example 3:
fig. 10 is a schematic view of an optical lens according to a third embodiment of the present invention. As shown in fig. 10 to 13, the first lens L1, the aperture Stop, the second lens L2, the filter IR, and the Image plane Image are disposed in this order from the object side to the Image side along the optical axis according to the third embodiment of the present invention; a first lens L1 having a first surface S1 and a second surface S2 whose central position is concave to the image side; the aperture Stop has a surface S3; a second lens L2 having a third surface S4 and a fourth surface S5 convex to the image side; the filter IR has a first surface S6 facing the object side and a second surface S7 facing the image side; the Image plane Image has a surface S8.
Lens data of the above lenses are shown in table 6 below.
[ TABLE 6 ]
The conditions satisfied by the above-described lens are shown in table 7.
[ TABLE 7 ]
Marking
|
Content of the presentation
|
Numerical value
|
f
|
Effective focal length of lens
|
1.037
|
HFOV
|
Half of maximum field angle
|
60
|
f1
|
Focal length of the first lens (L1)
|
-2.093
|
f2
|
Focal length of the second lens (L2)
|
0.825
|
Ho
|
The first lens (L1) object side surface edge ray height at maximum field angle.
|
0.365
|
Tfs
|
A first lens (L1) object spaceDistance from surface center to aperture Stop (Stop)
|
0.359
|
|
|
|
2、
|
0.1<(Tfs/f)/tan(HFOV)<0.5
|
0.200
|
3、
|
1<f/f2<2
|
1.257
|
4、
|
0.1<[Ho/tan(HFOV)]/f<0.5
|
0.203 |
In the above embodiment:
as shown in fig. 11 (light sector), it can be seen that the spherical aberration of the lower order has been corrected well and the spherical aberration of the higher order is smaller.
As shown in fig. 12 (field curvature and distortion diagram), the distortion curve is relatively smooth, and the definition of the expanded image is effectively improved.
As shown in fig. 13 (MTF resolution graph), it can be seen from the curves that MTF curves of the meridian and the sagittal of each field of view are relatively close, which indicates that the lens has relatively good imaging consistency in both directions of the meridian (T) and the sagittal (S), and the lens has relatively good imaging effect and resolution.
Example 4:
fig. 14 is a schematic view of an optical lens according to a fourth embodiment of the invention. As shown in fig. 14 to 17, the first lens L1, the aperture Stop, the second lens L2, the filter IR, and the Image plane Image are disposed in this order from the object side to the Image side along the optical axis according to the fourth embodiment of the present invention; a first lens L1 having a surface S1 and a second surface S2 whose central position is concave to the image side; the aperture Stop has a surface S3; a second lens L2 having a third surface S4 and a fourth surface S5 convex to the image side; the filter IR has a first surface S6 facing the object side and a second surface S7 facing the image side; the Image plane Image has a surface S8.
Lens data of the above lenses are shown in table 8 below.
[ TABLE 8 ]
The conditions satisfied by the above-described lens are shown in table 9.
[ TABLE 9 ]
Marking
|
Content of the presentation
|
Numerical value
|
f
|
Effective focal length of lens
|
1.038
|
HFOV
|
Half of maximum field angle
|
60
|
f1
|
First pass throughFocal length of mirror (L1)
|
-1.994
|
f2
|
Focal length of the second lens (L2)
|
0.813
|
Ho
|
The first lens (L1) object side surface edge ray height at maximum field angle.
|
0.365
|
Tfs
|
The distance from the center of the object space surface of the first lens (L1) to the aperture Stop (Stop)
|
0.356
|
|
|
|
2、
|
0.1<(Tfs/f)/tan(HFOV)<0.5
|
0.198
|
3、
|
1<f/f2<2
|
1.277
|
4、
|
0.1<[Ho/tan(HFOV)]/f<0.5
|
0.203 |
In the above embodiment:
as shown in fig. 15 (light sector), it can be seen that the spherical aberration of the lower order has been corrected well and the spherical aberration of the higher order is smaller.
As shown in fig. 16 (field curvature and distortion diagram), the distortion curve is relatively smooth, and the definition of the expanded image is effectively improved.
As shown in fig. 17 (MTF resolution graph), it can be seen from the curves that MTF curves of the meridian and the sagittal of each field of view are relatively close, which indicates that the lens has relatively good imaging consistency in both directions of the meridian (T) and the sagittal (S), and the lens has relatively good imaging effect and resolution.
As described above, the two-lens small-diameter large-field-angle lens according to the present invention satisfies both the size requirement for a small outer diameter of the lens and the function of a large field angle, and has a simple structure, and can perform photographing in a narrow space.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.