CN112068294A

CN112068294A - Zoom lens

Info

Publication number: CN112068294A
Application number: CN202011086830.2A
Authority: CN
Inventors: 邹文镔; 徐奉刚; 陈汇东
Original assignee: Sunny Optics Zhongshan Co Ltd
Current assignee: Sunny Optics Zhongshan Co Ltd
Priority date: 2020-10-12
Filing date: 2020-10-12
Publication date: 2020-12-11

Abstract

The invention relates to a zoom lens, which sequentially comprises a first fixed lens group with positive focal power, a first zoom lens group with negative focal power, an aperture Stop (STO), a second fixed lens group with positive focal power, a second zoom lens group with positive focal power, a focusing lens group with negative focal power and a third zoom lens group with positive focal power along the direction from an object side to an image side. The zoom lens can realize the zoom ratio of more than 20 times, meet the performance requirements of high magnification, small volume, large aperture and large target surface, and realize the full-focus 4K imaging. And through reasonable focal power distribution and selection of specific glass materials, chromatic aberration and secondary spectrum correction between 380 nm and 940nm of a long focal end are realized, and full-focal-length infrared confocal can be met. Can also meet the requirement of no virtual coke at the temperature range of-40 ℃ to +80 ℃.

Description

Zoom lens

Technical Field

The invention relates to the technical field of optical systems and device design, in particular to a zoom lens.

Background

With the development of security industry, the definition requirement of high-end markets on pictures is higher and higher, and 4K resolution ratio gradually becomes mainstream. The telescopic resolution of the existing large-magnification zoom lens is more than 2M and 4M level, and the market demand can not be met. Further, the zoom lens has a relationship in which the magnification change and the front end diameter and the total length of the lens are restricted from each other, and it is difficult to achieve miniaturization. The traditional "-zooming-focusing" or "two zooming-focusing" has limited structural freedom, is difficult to realize a long-focus large-aperture large target surface, has large infrared defocusing amount at the telescopic end, and is difficult to realize infrared confocal.

Disclosure of Invention

The present invention is directed to solving the above problems and to providing a zoom lens.

To achieve the above object, the present invention provides a zoom lens, which comprises, in order from an object side to an image side, a first fixed lens group having positive optical power, a first zoom lens group having negative optical power, an aperture stop, a second fixed lens group having positive optical power, a second zoom lens group having positive optical power, a focus lens group having negative optical power, and a third zoom lens group having positive optical power.

According to an aspect of the present invention, the first fixed lens group includes, in order in an object-side to image-side direction, a first lens having negative optical power, a second lens having positive optical power, a third lens having positive optical power, and a fourth lens having positive optical power.

According to one aspect of the invention, the first and second lenses comprise a cemented lens set.

According to an aspect of the present invention, the first zoom lens group includes, in order in an object-side to image-side direction, a fifth lens having a negative power, a sixth lens having a negative power, a seventh lens having a positive power, and an eighth lens having a negative power.

According to an aspect of the present invention, the second fixed lens group includes, in order in an object-side to image-side direction, a ninth lens having positive optical power, a tenth lens having negative optical power, and an eleventh lens having positive optical power.

According to an aspect of the present invention, the second zoom lens group includes, in order in an object-side to image-side direction, a twelfth lens having positive optical power, a thirteenth lens having negative optical power, and a fourteenth lens having positive optical power.

According to one aspect of the invention, the thirteenth lens and the fourteenth lens constitute a cemented lens set.

According to one aspect of the invention, the focusing lens group comprises a fifteenth lens with positive or negative optical power, a sixteenth lens with positive or negative optical power in sequence from the object side to the image side, and the fifteenth lens and the sixteenth lens form a cemented lens group.

According to an aspect of the invention, the third zoom lens group includes a seventeenth lens having a positive optical power.

According to an aspect of the present invention, focal lengths of the first fixed lens group, the first zoom lens group, the second fixed lens group, the second zoom lens group, the focus lens group, and the third zoom lens group are FG1, FG2, FG3, FG4, FG5, FG6 in this order, a focal length at a wide-angle end of the zoom lens is FW, satisfying: FG1/FW is more than or equal to 5.0 and less than or equal to 8.5, -FG 2/FW is more than or equal to 1.7 and less than or equal to-0.9, FG3/FW is more than or equal to 6.0 and less than or equal to 9.5, FG4/FW is more than or equal to 1.7, -FG 5/FW is more than or equal to 3.0 and less than or equal to-1.0, and FG6/FW is more than or equal to 2..

According to an aspect of the present invention, at least 3 lenses of the zoom lens are aspheric lenses, and both of the object-side surface and the image-side surface of the aspheric lenses are aspheric.

According to an aspect of the present invention, the stroke of the first zoom lens group is D2, the total length of the zoom lens is TTL, and: 0.25 < | D2/TTL | < 0.35.

According to an aspect of the present invention, the stroke of the first zoom lens group is D2, the stroke of the second zoom lens group is D4, and 0.3 ≦ D4/D2 ≦ 0.4 is satisfied.

According to one aspect of the invention, between the focal length FG2 of the first zoom lens group and the focal length FG5 of the focus lens group is satisfied: 0.5 < FG2/FG5 < 1.5.

According to an aspect of the invention, the maximum lens diameter of the first fixed lens group is Φ G1, the total length of the zoom lens is TTL, and: phi G1/TTL is more than 0.35 and less than 0.55.

The zoom lens is arranged according to the limitation, adopts a six-group framework with focal power of positive-negative-positive-negative-positive and four-group linkage mode of three-zoom-focusing, can realize zoom of more than 20 times, meets the performance requirements of high magnification, small volume, large aperture and large target surface, and realizes the full-focus 4K imaging.

The zoom lens realizes chromatic aberration and secondary spectrum correction between 380 and 940nm telephoto ends through reasonable collocation of positive and negative focal powers and the practicability of a specific aspheric lens, and can meet full-focus infrared confocal.

The zoom lens is arranged according to the limitation, can realize the zoom ratio of more than 20 times, meets the performance requirements of high magnification, small volume, large aperture and large target surface, and can realize the full-focus 4K imaging. And through reasonable focal power distribution and selection of specific glass materials, chromatic aberration and secondary spectrum correction between 380 nm and 940nm of a long focal end are realized, and full-focal-length infrared confocal can be met. Can also meet the requirement of no virtual coke at the temperature range of-40 ℃ to +80 ℃.

Drawings

FIG. 1 is a schematic view showing a configuration of a zoom lens according to embodiment 1 of the present invention;

fig. 2 schematically shows an MTF chart at the wide-angle end of a zoom lens according to embodiment 1 of the present invention;

FIG. 3 is a schematic representation of an MTF chart at the telephoto end of a zoom lens according to embodiment 1 of the present invention;

FIG. 4 schematically shows a 850nm out-of-focus curve at the wide-angle end of a zoom lens according to embodiment 1 of the present invention;

FIG. 5 is a schematic view showing a structure of a zoom lens according to embodiment 2 of the present invention;

fig. 6 schematically shows an MTF chart at the wide-angle end of a zoom lens according to embodiment 2 of the present invention;

FIG. 7 schematically shows an MTF chart at the telephoto end of a zoom lens according to embodiment 2 of the present invention;

FIG. 8 schematically shows a 850nm out-of-focus curve at the wide-angle end of a zoom lens according to embodiment 2 of the present invention;

FIG. 9 is a schematic view showing a structure of a zoom lens according to embodiment 3 of the present invention;

fig. 10 schematically shows an MTF chart at the wide-angle end of a zoom lens according to embodiment 3 of the present invention;

FIG. 11 is a schematic representation of an MTF chart at the telephoto end of a zoom lens according to embodiment 3 of the present invention;

fig. 12 schematically shows a 850nm defocus graph of the zoom lens according to embodiment 3 of the present invention at the wide-angle end.

Detailed Description

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 embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

The present invention is described in detail below with reference to the drawings and the specific embodiments, which are not repeated herein, but the embodiments of the present invention are not limited to the following embodiments.

Referring to fig. 1, the present invention provides a zoom lens, which sequentially includes a first fixed lens group, a first zoom lens group, an aperture stop STO, a second fixed lens group, a second zoom lens group, a focusing lens group, and a third zoom lens group along an object-side to image-side direction. In the present invention, the first fixed lens group has positive focal power, the first zoom lens group has negative focal power, the second fixed lens group has positive focal power, the second zoom lens group has positive focal power, the focus lens group has negative focal power, and the third zoom lens group has positive focal power.

In the zoom lens of the present invention, the first zoom lens group, the second zoom lens group, and the third zoom lens group are movable along the optical axis, and are used for optical zooming between the telephoto end and the wide-angle end of the zoom lens of the present invention. The focusing lens group can move along the optical axis and is used for compensating the change of the image surface position in the optical zooming process.

Specifically, in the zoom lens of the present invention, the first fixed lens group includes, in order from the object side to the image side, a first lens L1 having negative optical power, a second lens L2 having positive optical power, a third lens L3 having positive optical power, and a fourth lens L4 having positive optical power, and the first lens L1 and the second lens L2 form a cemented lens group.

In the present invention, the first zoom lens group includes, in order in an object-side to image-side direction, a fifth lens L5 having negative optical power, a sixth lens L6 having negative optical power, a seventh lens L7 having positive optical power, and an eighth lens L8 having negative optical power.

The second fixed lens group of the present invention includes, in order in the object-to-image direction, a ninth lens L9 having positive optical power, a tenth lens L10 having negative optical power, and an eleventh lens L11 having positive optical power.

The second zoom lens group of the present invention includes, in order in an object-to-image direction, a twelfth lens L12 having a positive optical power, a thirteenth lens L13 having a negative optical power, and a fourteenth lens L14 having a positive optical power, and the thirteenth lens L13 and the fourteenth lens L14 constitute a cemented lens group.

The focusing lens group of the invention sequentially comprises a fifteenth lens L15 with positive power or negative power, a sixteenth lens L16 with positive power or negative power, and a cemented lens group consisting of the fifteenth lens L15 and the sixteenth lens L16 along the object-side to image-side direction.

The third zoom lens group of the present invention includes a seventeenth lens L17 having positive optical power.

In the zoom lens, at least 3 lenses in the zoom lens are aspheric lenses, and the object side surface and the image side surface of each aspheric lens are aspheric surfaces.

In the zoom lens of the present invention, the focal lengths of the first fixed lens group G1, the first zoom lens group G2, the second fixed lens group G3, the second zoom lens group G4, the focus lens group G5, and the third zoom lens group G6 are FG1, FG2, FG3, FG4, FG5, and FG6 in this order, and the focal length at the wide-angle end of the zoom lens is FW, and the following conditions are satisfied: FG1/FW is more than or equal to 5.0 and less than or equal to 8.5, -FG 2/FW is more than or equal to 1.7 and less than or equal to-0.9, FG3/FW is more than or equal to 6.0 and less than or equal to 9.5, FG4/FW is more than or equal to 1.7, -FG 5/FW is more than or equal to 3.0 and less than or equal to-1.0, and FG6/FW is more than or equal to 2.. A focal length FG2 of the first zoom lens group and a focal length FG5 of the focus lens group satisfy: 0.5 < FG2/FG5 < 1.5.

In the present invention, the stroke of the first zoom lens group is D2, the total length of the zoom lens of the present invention is TTL, and the following requirements are satisfied: 0.25 < | D2/TTL | < 0.35.

The stroke of the second zoom lens group is D4, and the relationship between the stroke D4 of the second zoom lens group and the stroke D2 of the first zoom lens group is satisfied: the absolute value of D4/D2 is more than or equal to 0.3 and less than or equal to 0.4.

In the present invention, the maximum lens diameter of the first fixed lens group is Φ G1, and the total length of the zoom lens of the present invention is TTL, satisfying: phi G1/TTL is more than 0.35 and less than 0.55.

In conclusion, the zoom lens provided by the invention is arranged according to the above limitation, can realize the zoom ratio exceeding 20 times, meets the performance requirements of high magnification, small volume, large aperture and large target surface, and can realize the full-focus 4K imaging. And through reasonable focal power distribution and selection of specific glass materials, chromatic aberration and secondary spectrum correction between 380 nm and 940nm of a long focal end are realized, and full-focal-length infrared confocal can be met. Can also meet the requirement of no virtual coke at the temperature range of-40 ℃ to +80 ℃.

The imaging lens according to the present invention is specifically explained below by giving 3 specific groups of embodiments according to the above-described arrangement of the present invention. The zoom lens comprises 17 lenses, wherein a first lens L1 and a second lens L2 form a cemented lens group, a thirteenth lens L13 and a fourteenth lens L14 form a cemented lens group, a fifteenth lens L15 and a sixteenth lens L16 form a cemented lens group, an aperture stop S, a filter and an imaging surface are added, 35 optical surfaces are included, and the 35 optical surfaces are numbered as S1-S35 in sequence for convenience of description.

Three sets of embodiment data are as in table 1 below:

TABLE 1

The first implementation mode comprises the following steps:

fig. 1 is a schematic diagram showing a zoom lens structure according to a first embodiment of the present invention.

Table 2 below lists relevant parameters of each lens of the present embodiment, including surface type, radius of curvature, thickness, refractive index of material, abbe number:

TABLE 2

Table 3 shows the aspherical surface coefficients of the aspherical lenses in the present embodiment, K is a conic constant of the surface, and A, B, C, D, E are aspherical surface coefficients of fourth order, sixth order, eighth order, tenth order, and twelfth order, respectively.

Serial number

K

A

B

C

D

E

S16

0.235816

2.52E-06

9.09E-09

-2.34E-10

2.16E-12

-7.79E-15

S17

293.6179

2.62E-06

1.32E-08

-3.27E-10

4.02E-12

-1.87E-14

S22

-0.3975558

-3.47E-06

2.49E-08

-1.29E-10

4.35E-13

-1.08E-15

S23

-0.5530994

8.70E-06

-4.94E-08

1.31E-09

-1.55E-11

6.74E-14

S30

-17.32177

-4.16E-06

1.43E-07

-3.17E-09

3.20E-11

-1.25E-13

S31

-0.4694071

6.96E-07

7.32E-08

-2.50E-10

-5.77E-12

4.33E-14

TABLE 3

In the present embodiment, the ninth lens L9, the twelfth lens L12, and the seventeenth lens L17 are aspherical lenses.

Table 4 lists the wide-angle end, telephoto end magnification variation data as follows:

	wide angle end	Long coke end
			T1	1.2	46.4
T2	46.4	1.2
			T3	17.1	1.5
T4	3.5	11.2
			T5	1.5	19.4
T6	11.5	1.5

TABLE 4

Fig. 2 to 4 schematically show MTF charts at the wide-angle end, MTF charts at the telephoto end and 850nm defocus graphs at the wide-angle end of the zoom lens according to embodiment 1 of the present invention. The attached drawings show that the zoom lens obtained according to the embodiment 1 of the invention realizes the optical zoom with the maximum aperture of 1.6, the zoom ratio of more than 20 times, and the correction of the position chromatic aberration and the magnification chromatic aberration between 380 nm and 940nm, and meets the requirements of the full-focus 4K resolution, small lens size and large magnification.

The second embodiment:

fig. 5 is a schematic diagram showing a zoom lens structure according to a second embodiment of the present invention.

Table 5 below lists relevant parameters of each lens of the present embodiment, including surface type, radius of curvature, thickness, refractive index of material, abbe number:

TABLE 5

Table 6 shows the aspherical surface coefficients of the aspherical lenses in the present embodiment, K is a conic constant of the surface, and A, B, C, D, E are aspherical surface coefficients of fourth order, sixth order, eighth order, tenth order, and twelfth order, respectively.

Serial number

K

A

B

C

D

E

S10

3.54E-01

-3.87E-06

3.34E-08

-9.75E-10

1.58E-11

-9.87E-13

S11

-1.20E+00

1.20E-05

1.54E-08

-7.02E-10

5.18E-11

-1.73E-13

S17

3.89E-01

-4.25E-06

3.67E-08

-1.07E-09

8.74E-11

-2.05E-13

S18

-1.10E+00

1.32E-05

1.69E-08

-7.71E-10

3.30E-11

-2.90E-13

S23

3.17E-01

-3.47E-06

2.99E-08

-8.73E-10

2.42E-11

-4.68E-13

S24

-8.96E-01

1.08E-05

1.38E-08

-6.29E-10

1.06E-11

-6.55E-13

S31

4.07E-01

-4.45E-06

3.84E-08

-1.12E-09

2.82E-11

-2.15E-13

S32

-1.15E+00

1.38E-05

1.77E-08

-8.08E-10

5.36E-11

-7.99E-13

TABLE 6

In the present embodiment, the sixth lens L6, the ninth lens L9, the twelfth lens L12, and the seventeenth lens L17 are aspherical lenses.

Table 7 lists the wide-angle end, telephoto end magnification variation data as follows:

TABLE 7

Fig. 6 to 8 schematically show MTF charts at the wide-angle end, MTF charts at the telephoto end and 850nm defocus graphs at the wide-angle end of the zoom lens according to embodiment 2 of the present invention. With reference to the accompanying drawings, it can be known that the zoom lens obtained according to embodiment 2 of the present invention realizes an optical zoom having a maximum aperture of 1.6, a zoom ratio exceeding 20 times, and a positional chromatic aberration and a magnification chromatic aberration between 380 nm and 940nm, and satisfies a full-focus 4K resolution, a small lens size, and a large magnification.

The third embodiment is as follows:

fig. 9 is a block diagram schematically showing a zoom lens according to a third embodiment of the present invention.

Table 8 below lists relevant parameters of each lens of the present embodiment, including surface type, radius of curvature, thickness, refractive index of material, abbe number:

TABLE 8

Table 9 shows the aspherical surface coefficients of the aspherical lenses in the present embodiment, K is a conic constant of the surface, and A, B, C, D, E are aspherical surface coefficients of fourth order, sixth order, eighth order, tenth order, and twelfth order, respectively.

TABLE 9

In the present embodiment, the fifth lens L5, the twelfth lens L12, and the seventeenth lens L17 are aspherical lenses.

Table 10 lists the wide-angle end, telephoto end magnification variation data as follows:

	wide angle end	Long coke end
			T1	1.5	44.3
T2	44.3	1.5
			T3	16.7	1.5
T4	4	12
			T5	1.5	20.2
T6	13	1.5

Fig. 10 to 12 schematically show MTF charts at the wide angle end, an MTF chart at the telephoto end of the head, and 850nm defocus graphs at the wide angle end of the zoom lens according to embodiment 3 of the present invention. With reference to the accompanying drawings, it can be known that the zoom lens obtained according to embodiment 3 of the present invention realizes optical zooming with a maximum aperture of 1.6, a zoom ratio exceeding 20 times, and positional chromatic aberration and magnification chromatic aberration between 380 nm and 940nm corrected, and satisfies a full-focus 4K resolution, a small lens size, and a large magnification.

The above description is only one embodiment of the present invention, and is not intended to limit the present invention, and it is apparent to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A zoom lens is characterized by sequentially comprising a first fixed lens group with positive focal power, a first zoom lens group with negative focal power, an aperture Stop (STO), a second fixed lens group with positive focal power, a second zoom lens group with positive focal power, a focusing lens group with negative focal power and a third zoom lens group with positive focal power along the direction from an object side to an image side.

2. The zoom lens according to claim 1, wherein the first fixed lens group includes, in order in an object-to-image direction, a first lens (L1) having negative optical power, a second lens (L2) having positive optical power, a third lens (L3) having positive optical power, and a fourth lens (L4) having positive optical power.

3. The zoom lens of claim 2, wherein the first lens (L1) and the second lens (L2) comprise a cemented lens group.

4. The zoom lens according to claim 1, wherein the first zoom lens group includes, in order in an object-to-image direction, a fifth lens (L5) having negative optical power, a sixth lens (L6) having negative optical power, a seventh lens (L7) having positive optical power, and an eighth lens (L8) having negative optical power.

5. The zoom lens according to claim 1, wherein the second fixed lens group includes, in order in an object-to-image direction, a ninth lens (L9) having positive optical power, a tenth lens (L10) having negative optical power, and an eleventh lens (L11) having positive optical power.

6. The zoom lens according to claim 1, wherein the second zoom lens group includes, in order in an object-to-image direction, a twelfth lens (L12) having positive optical power, a thirteenth lens (L13) having negative optical power, and a fourteenth lens (L14) having positive optical power.

7. The zoom lens of claim 6, wherein the thirteenth lens (L13) and the fourteenth lens (L14) constitute a cemented lens group.

8. The zoom lens according to claim 1, wherein the focusing lens group comprises, in order in an object-to-image direction, a fifteenth lens (L15) having positive or negative optical power, a sixteenth lens (L16) having positive or negative optical power, and the fifteenth lens (L15) and the sixteenth lens (L16) form a cemented lens group.

9. The zoom lens according to claim 1, wherein the third zoom lens group includes a seventeenth lens (L17) having positive optical power.

10. A zoom lens according to any one of claims 1 to 9, wherein the focal lengths of the first fixed lens group, first zoom lens group, second fixed lens group, second zoom lens group, focus lens group and third zoom lens group are FG1, FG2, FG3, FG4, FG5, FG6 in this order, and the focal length at the wide-angle end of the zoom lens is FW, satisfying: FG1/FW is more than or equal to 5.0 and less than or equal to 8.5, -FG 2/FW is more than or equal to 1.7 and less than or equal to-0.9, FG3/FW is more than or equal to 6.0 and less than or equal to 9.5, FG4/FW is more than or equal to 1.7, -FG 5/FW is more than or equal to 3.0 and less than or equal to-1.0, and FG6/FW is more than or equal to 2..

11. A zoom lens according to any one of claims 1 to 9, wherein at least 3 lenses of the zoom lens are aspherical lenses, and both of the object-side surface and the image-side surface of the aspherical lenses are aspherical.

12. The zoom lens according to any one of claims 1 to 9, wherein the stroke of the first zoom lens group is D2, and the total length of the zoom lens is TTL, which satisfies: 0.25 < | D2/TTL | < 0.35.

13. The zoom lens of any one of claims 1 to 9, wherein the stroke of the first zoom lens group is D2, and the stroke of the second zoom lens group is D4, and 0.3 ≦ D4/D2| ≦ 0.4 is satisfied.

14. The zoom lens of claim 10, wherein a focal length FG2 of the first zoom lens group and a focal length FG5 of the focus lens group satisfy: 0.5 < FG2/FG5 < 1.5.

15. The zoom lens according to any one of claims 1 to 9, wherein the maximum lens diameter of the first fixed lens group is Φ G1, and the total length of the zoom lens is TTL, satisfying: phi G1/TTL is more than 0.35 and less than 0.55.