CN113296252B - Zoom lens - Google Patents

Abstract

The invention discloses a zoom lens, which comprises a first fixed lens group, a zoom lens group, a second fixed lens group, a focusing lens group and an optical filter, wherein the first fixed lens group, the zoom lens group, the second fixed lens group, the focusing lens group and the optical filter are sequentially arranged from an object side to an image side along an optical axis; the zoom lens further satisfies the following condition: FA/FC is more than or equal to 1.32 and less than or equal to 1.97, FB/FC is more than or equal to 0.9 and less than or equal to-0.18,0 and less than or equal to FD/FC and less than or equal to 1.1, wherein FA is the focal length of the first fixed lens group, FB is the focal length of the zoom lens group, FC is the focal length of the second fixed lens group, and FD is the focal length of the focusing lens group. The lens has excellent confocal imaging capability under visible light and infrared light, has a temperature compensation function, does not need to be focused again when switching day and night, has clear imaging, small volume, large image surface, wide application range and low cost, and can be matched with various types of camera equipment to meet various use requirements.

Description

a zoom lens

technical field

The invention belongs to the technical field of optical lenses, and in particular relates to a zoom lens.

Background technique

With the development of AI face recognition technology, the zoom lens is conducive to further improving the development and application space in this field. However, in the field of AI face recognition, it needs to be based on clearer images to achieve its excellent recognition accuracy and processing efficiency. Therefore, higher requirements are put forward for the aperture, image plane, resolution, infrared performance and high and low temperature performance of the camera lens. However, the currently used lenses generally have the following shortcomings: small aperture, which cannot meet the brightness requirements of images in low-light environments; large image area and small size cannot be balanced, and cannot meet the space requirements of the lens; low resolution, the current mainstream 1080P lens , the resolution is 2 million, which obviously cannot meet the high-pixel requirements of face recognition; the infrared performance and high and low temperature performance cannot be taken into account, and the high and low temperature performance is often sacrificed to meet the day and night confocal requirements, which cannot meet the high and low temperature environment. The real-time requirements of face recognition make it difficult to guarantee stable working performance.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the above problems and propose a zoom lens that can achieve excellent confocal imaging capabilities under visible and infrared light, and has a temperature compensation function, and does not need to refocus when switching between day and night. It is large and has a wide range of applications, which can effectively improve the efficiency of light transmission and reduce production costs, and can be matched with various types of camera equipment to meet the needs of use.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A zoom lens proposed by the present invention includes a first fixed lens group, a zoom lens group, a second fixed lens group, a focus lens group and an optical filter arranged in sequence from the object side to the image side along the optical axis. , the zoom lens group and the focus lens group move along the optical axis respectively;

The zoom lens also meets the following conditions:

1.32≤FA/FC≤1.97, -0.9≤FB/FC≤-0.18, 0≤FD/FC≤1.1

Wherein, FA is the focal length of the first fixed lens group, FB is the focal length of the zoom lens group, FC is the focal length of the second fixed lens group, and FD is the focal length of the focusing lens group.

Preferably, the zoom lens also satisfies:

0≤FW/FC≤0.5

Among them, FW is the focal length of the wide-angle end of the zoom lens.

Preferably, the first fixed lens group has positive refraction power, the zoom lens group has negative refraction power, the second fixed lens group has positive refraction power, and the focusing lens group has positive refraction power.

Preferably, the first fixed lens group includes a first lens with negative refractive power, a second lens with positive refractive power, and a third lens with positive refractive power arranged sequentially from the object side to the image side;

The zoom lens group includes a fourth lens with negative refractive power, a fifth lens with negative refractive power and a sixth lens with positive refractive power arranged sequentially from the object side to the image side;

The second fixed lens group includes a seventh lens with positive refractive power, an eighth lens with positive refractive power, a ninth lens with positive refractive power and a tenth lens with negative refractive power arranged in sequence from the object side to the image side. lens;

The focusing lens group includes an eleventh lens with positive refractive power, a twelfth lens with positive refractive power, and a thirteenth lens with negative refractive power arranged in sequence from the object side to the image side.

Preferably, the first lens, the third lens, the fourth lens, the sixth lens, the tenth lens and the thirteenth lens are all flint glass, and the second lens, the fifth lens, the seventh lens, the eighth lens, the ninth lens The lenses, the eleventh lens and the twelfth lens are all crown glasses.

Preferably, the zoom lens includes at least one cemented lens group formed by cementing adjacent lenses.

Preferably, the zoom lens also satisfies:

为变焦镜头所覆盖的靶面直径，TTL为变焦镜头的总长。in,

is the diameter of the target surface covered by the zoom lens, and TTL is the total length of the zoom lens.

Preferably, the zoom lens further includes an aperture STO located between the zoom lens group and the second fixed lens group.

Preferably, both the first fixed lens group and the second fixed lens group include at least one lens that satisfies:

1.43≤nd≤1.64, 60≤vd≤96

Among them, nd is the refractive index, and vd is the Abbe number.

Compared with prior art, the beneficial effect of the present invention is:

1) By reasonably setting the focal length, lens quantity and shape between each lens group, the overall quality is balanced, which is conducive to reducing the assembly tolerance between lens groups, facilitating assembly and improving lens assembly accuracy;

2) Optimize the distribution of the focal power of the lens group to achieve excellent confocal imaging capabilities for the visible and infrared spectra. At the same time, it has a temperature compensation function that solves the problem of focus drift in high and low temperature environments. There is no false focus in the temperature range of ℃, and it still has good resolution in the state of large aperture, achieving the effect of clear imaging, and has a wide range of applications;

3) It can ensure a large field of view while reducing the overall length, effectively improving light transmission efficiency and reducing production costs. The lens is small in size and large in image area, and can be matched with various types of camera equipment to meet the needs of use;

4) Through the combination of crown glass and flint glass, the correction of chromatic aberration and secondary spectrum in the 380-850nm band can be realized, and the resolution can be guaranteed without refocusing when switching between day and night.

Description of drawings

Fig. 1 is the structural diagram of zoom lens of the present invention;

Fig. 2 is the wide-angle end MTF diagram of the zoom lens of the present invention under normal temperature and visible light;

Fig. 3 is the wide-angle end MTF diagram of the zoom lens of the present invention under visible light at -40°C;

Fig. 4 is the wide-angle end MTF diagram of the zoom lens of the present invention under visible light at +80°C;

Fig. 5 is the wide-angle end MTF diagram of the zoom lens of the present invention under normal temperature infrared light;

Fig. 6 is the wide-angle end MTF diagram of the zoom lens of the present invention under -40°C infrared light;

Fig. 7 is the wide-angle end MTF diagram of the zoom lens of the present invention under +80°C infrared light;

Fig. 8 is the telephoto end MTF diagram of the zoom lens of the present invention under normal temperature and visible light;

Fig. 9 is the telephoto end MTF diagram of the zoom lens of the present invention under visible light at -40°C;

Fig. 10 is the MTF diagram of the zoom lens of the present invention at the telephoto end under visible light at +80°C;

Fig. 11 is the telephoto end MTF diagram of the zoom lens of the present invention under normal temperature infrared light;

Fig. 12 is the telephoto end MTF diagram of the zoom lens of the present invention under -40°C infrared light;

Fig. 13 is the MTF diagram of the telephoto end of the zoom lens of the present invention under +80°C infrared light.

Description of Reference Signs: 1. First fixed lens group; 2. Zoom lens group; 3. Second fixed lens group; 4. Focusing lens group; 5. Optical filter; 11. First lens; 12. Second lens ;13, the third lens; 21, the fourth lens; 22, the fifth lens; 23, the sixth lens; 31, the seventh lens; 32, the eighth lens; 33, the ninth lens; 34, the tenth lens; 41 , the eleventh lens; 42, the twelfth lens; 43, the thirteenth lens; STO, aperture; IMA, image plane.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the application with reference to the drawings in the embodiments of the application. Apparently, the described embodiments are only some, not all, embodiments of the application. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the application. The terms used herein in the description of the application are only for the purpose of describing specific embodiments, and are not intended to limit the application.

As shown in Figures 1-13, a zoom lens includes a first fixed lens group 1, a zoom lens group 2, a second fixed lens group 3, a focusing lens group 4 and The optical filter 5, when focusing, the zoom lens group 2 and the focusing lens group 4 move along the optical axis respectively;

The zoom lens also meets the following conditions:

1.32≤FA/FC≤1.97, -0.9≤FB/FC≤-0.18, 0≤FD/FC≤1.1

Wherein, FA is the focal length of the first fixed lens group 1 , FB is the focal length of the zoom lens group 2 , FC is the focal length of the second fixed lens group 3 , and FD is the focal length of the focus lens group 4 .

In one embodiment, the zoom lens also satisfies:

0≤FW/FC≤0.5

Among them, FW is the focal length of the wide-angle end of the zoom lens.

When the lens works, the light passes through the first fixed lens group 1, the zoom lens group 2, the second fixed lens group 3 and the focus lens group 4 to adjust the optical path, and then passes through the optical filter 5 to form an image on the image plane, and the zoom lens Group 2 can move along the optical axis for optical zooming between the wide-angle end and the telephoto end of the zoom lens, and the focus lens group 4 can also move along the optical axis for correcting the image plane of the zoom lens group 2 during zooming location changes. And by reasonably setting the focal length between the lens groups, the overall quality is ensured to be balanced, which is conducive to reducing the assembly tolerance between the lens groups, facilitating assembly and improving the assembly accuracy of the lens.

In one embodiment, the first fixed lens group 1 has positive refractive power, the zoom lens group 2 has negative refractive power, the second fixed lens group 3 has positive refractive power, and the focusing lens group 4 has positive refractive power.

In one embodiment, the first fixed lens group 1 includes a first lens 11 with negative refractive power, a second lens 12 with positive refractive power and a third lens with positive refractive power arranged in sequence from the object side to the image side. lens 13;

The zoom lens group 2 includes a fourth lens 21 with negative refractive power, a fifth lens 22 with negative refractive power, and a sixth lens 23 with positive refractive power arranged in sequence from the object side to the image side;

The second fixed lens group 3 includes a seventh lens 31 with positive refractive power, an eighth lens 32 with positive refractive power, a ninth lens 33 with positive refractive power, and a ninth lens 33 with negative refractive power arranged in sequence from the object side to the image side. degree tenth lens 34;

The focusing lens group 4 includes an eleventh lens 41 with positive refractive power, a twelfth lens 42 with positive refractive power, and a thirteenth lens 43 with negative refractive power arranged in order from the object side to the image side.

The lens realizes the excellent confocal imaging capability of the visible and infrared spectrum through the optimal distribution of the focal power of the lens group and the reasonable configuration of the number and shape of the lens. The problem of focus drift, there is no virtual focus in the temperature range of -40°C to 80°C, and it still has good resolution at large apertures, achieving clear imaging effects, and has a wide range of applications. It should be noted that the number and shape of each lens group of the lens can be adjusted arbitrarily under the condition that the optical power requirement is met.

In one embodiment, the first lens 11, the third lens 13, the fourth lens 21, the sixth lens 23, the tenth lens 34 and the thirteenth lens 43 are all flint glass, the second lens 12, the fifth lens 22 , the seventh lens 31, the eighth lens 32, the ninth lens 33, the eleventh lens 41 and the twelfth lens 42 are crown glass. Realize the correction of chromatic aberration and secondary spectrum in the 380-850nm band, and ensure the resolution without refocusing when switching between day and night.

In one embodiment, the zoom lens includes at least one cemented lens group formed by cementing adjacent lenses. To eliminate chromatic aberration and improve image quality.

In one embodiment, the zoom lens also satisfies:

为变焦镜头所覆盖的靶面直径，TTL为变焦镜头的总长。in,

is the diameter of the target surface covered by the zoom lens, and TTL is the total length of the zoom lens.

By controlling the diameter of the target surface and the total length of the zoom lens, the lens can obtain a lens with a small volume and a large image surface, which can meet the use requirements of various types of imaging equipment.

In an embodiment, the zoom lens further includes an aperture STO located between the zoom lens group 2 and the second fixed lens group 3 . The diaphragm STO is set behind the zoom lens group 2, and the rear of the diaphragm STO is realized, so that the maximum aperture of the zoom lens can reach F1.4, and the amount of light entering in a low-light environment is sufficient to ensure the brightness of the image and improve the image quality .

In one embodiment, both the first fixed lens group 1 and the second fixed lens group 3 include at least one lens that satisfies:

1.43≤nd≤1.64, 60≤vd≤96

Among them, nd is the refractive index, and vd is the Abbe number.

The lens realizes the correction of chromatic aberration and secondary spectrum in the 380-850nm band by controlling the material properties of the lenses in the first fixed lens group 1 and the second fixed lens group 3, such as the combination of crown glass and flint glass. Good resolution can be guaranteed without refocusing when switching between day and night.

Specifically, as shown in Figure 1, in the present embodiment, the first fixed lens group 1 has positive refractive power, the zoom lens group 2 has negative refractive power, the second fixed lens group 3 has positive refractive power, and the focusing lens group 4 has Positive power. The first fixed lens group 1 includes three lenses, the zoom lens group 2 includes three lenses, the second fixed lens group 3 includes four lenses, and the focusing lens group 4 includes three lenses. Wherein, the first lens 11 is a meniscus lens with negative power, the second lens 12 is a meniscus lens with positive power, the third lens 13 is a meniscus lens with positive power, and the fourth lens 13 is a meniscus lens with positive power. Lens 21 is a biconcave lens with negative refractive power, the fifth lens 22 is a biconcave lens with negative refractive power, the sixth lens 23 is a meniscus lens with positive refractive power, and the seventh lens 31 is a meniscus lens with positive refractive power. The eighth lens 32 is a biconvex lens with positive refractive power, the ninth lens 33 is a biconvex lens with positive refractive power, and the tenth lens 34 is a biconvex lens with negative refractive power. Concave lens, the eleventh lens 41 is a biconvex lens with positive refractive power, the twelfth lens 42 is a biconvex lens with positive refractive power, and the thirteenth lens 43 is a biconcave lens with negative refractive power , the first lens 11 and the second lens 12 form a first cemented lens group, the ninth lens 33 and the tenth lens 34 form a second cemented lens group, and the twelfth lens 42 and the thirteenth lens 43 form a third cemented lens group , the diaphragm STO is an iris diaphragm.

The focal length setting in the present embodiment is as shown in table 1:

Table 1

FA/FC 1.66 FB/FC -0.29 FD/FC 0.45 FW/FC 0.18 Total number of cemented lens groups 3

Each lens is a spherical lens, and the specific relevant parameters include the radius of curvature, thickness, refractive index and Abbe number, as shown in Table 2:

Table 2

In Table 2, numbering is carried out according to the number of optical surfaces. Since there are cemented lens groups composed of multiple lenses, the same number is used on the cemented surface. For example, L1&L2, 33&34, 42&43 correspond to the first cemented lens group and the second Two cemented lens groups and a third cemented lens group. Therefore, in this embodiment, numbers S1 to S23 correspond to the mirror surfaces of the lenses sequentially arranged from the object side to the image side, and S24 and S25 are the object-side mirror surface and the image-side mirror surface of the optical filter 5 respectively.

The zoom parameters of the wide-angle end and the telephoto end are shown in Table 3, where: Z1 is the distance between the first fixed lens group 1 and the zoom lens group 2, Z2 is the distance between the zoom lens group 2 and the second fixed lens group 3, Z3 Z4 is the distance between the second fixed lens group 3 and the focusing lens group 4, and Z4 is the distance between the focusing lens group 4 and the image plane.

table 3

wide-angle end telephoto end Z1 2.42 27.79 Z2 27.46 2.09 Z3 10.04 0.69 Z4 1.5 10.84

According to the relevant parameter settings in Table 1, Table 2, and Table 3, Figure 2-4 shows the wide-angle end MTF diagrams of the lens at room temperature, -40°C and +80°C under visible light, and Figure 5-7 shows the lens at room temperature , -40°C and +80°C infrared light at the wide-angle end. Figure 8-10 shows the telephoto end MTF of the lens at room temperature, -40°C and +80°C under visible light. Figure 11-13 shows the lens at the telephoto end. In the telephoto end MTF diagrams of the lens at room temperature, -40°C and +80°C infrared light, the MTF did not decrease significantly. To sum up, this lens takes into account the confocal capabilities of infrared and visible light, and through the adjustment of Z1, Z2, Z3, and Z4, the zoom magnification is large, and the large aperture of F1.4 can be realized. It is small in size and large in target area. In the temperature range of -40°C to 80°C, there is no false focus, the image is clear, and the application range is wide.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only represent the more specific and detailed embodiments described in the present application, but should not be construed as limiting the scope of the patent for the invention. It should be noted that, for those skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the scope of protection of the patent application should be based on the appended claims.

Claims (7)

1. A zoom lens, characterized in that: the zoom lens is composed of a first fixed lens group (1), a zoom lens group (2), a second fixed lens group (3), a focusing lens group (4) and an optical filter (5) which are arranged in sequence from an object side to an image side along an optical axis, when focusing is carried out, the zoom lens group (2) and the focusing lens group (4) respectively move along the optical axis, the first fixed lens group (1) has positive focal power, the zoom lens group (2) has negative focal power, the second fixed lens group (3) has positive focal power, and the focusing lens group (4) has positive focal power, wherein:

the first fixed lens group (1) is composed of a first lens (11) with negative focal power, a second lens (12) with positive focal power and a third lens (13) with positive focal power which are arranged in sequence from the object side to the image side;

the zoom lens group (2) is composed of a fourth lens (21) with negative focal power, a fifth lens (22) with negative focal power and a sixth lens (23) with positive focal power which are arranged in sequence from the object side to the image side;

the second fixed lens group (3) is composed of a seventh lens (31) with positive focal power, an eighth lens (32) with positive focal power, a ninth lens (33) with positive focal power and a tenth lens (34) with negative focal power which are arranged in sequence from the object side to the image side;

the focusing lens group (4) is composed of an eleventh lens (41) with positive focal power, a twelfth lens (42) with positive focal power and a thirteenth lens (43) with negative focal power, which are arranged in sequence from the object side to the image side;

the zoom lens further satisfies the following conditions:

1.32≤FA/FC≤1.97，-0.9≤FB/FC≤-0.18，0≤FD/FC≤1.1

and FA is the focal length of the first fixed lens group (1), FB is the focal length of the zoom lens group (2), FC is the focal length of the second fixed lens group (3), and FD is the focal length of the focusing lens group (4).

2. The zoom lens according to claim 1, wherein: the zoom lens further satisfies:

0≤FW/FC≤0.5

wherein FW is a wide-angle end focal length of the zoom lens.

3. The zoom lens according to claim 1, wherein: the first lens (11), the third lens (13), the fourth lens (21), the sixth lens (23), the tenth lens (34) and the thirteenth lens (43) are all made of flint glass, and the second lens (12), the fifth lens (22), the seventh lens (31), the eighth lens (32), the ninth lens (33), the eleventh lens (41) and the twelfth lens (42) are all made of crown glass.

4. The zoom lens according to claim 1, wherein: the zoom lens comprises at least one cemented lens group formed by adjacent lenses through cementing.

5. The zoom lens according to claim 1, wherein: the zoom lens further satisfies:

0.05≤

/TTL

wherein,

and the TTL is the total length of the zoom lens and is the diameter of a target surface covered by the zoom lens.

6. The zoom lens according to claim 1, wherein: the zoom lens further comprises a stop STO, which is located between the zoom lens group (2) and the second fixed lens group (3).

7. The zoom lens according to any one of claims 1 to 6, wherein: the first fixed lens group (1) and the second fixed lens group (3) both comprise at least one lens, and the following conditions are satisfied:

1.43≤nd≤1 .64，60≤vd≤96

where nd is a refractive index and vd is an Abbe number.

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