# US 9,753,263 B2 · Zoom lens system

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- Number: US 9,753,263 B2
- Document ID: US9753263B2
- Status: Granted
- Kind: B2
- Application number: 14/855,851
- Filed: 2015-09-16
- Published: 2016-12-15
- Granted: 2017-09-05
- Earliest claimed: 2015-06-09
- Assignees: Hanwha Techwin Co., Ltd.
- Applicants: Hanwha Techwin Co., Ltd.
- Inventors: Jiyeong Yoo
- Web page: https://patentgrep.com/patent/US9753263B2

## CPC

- G02B 15/177: having a negative front lens or group of lenses
- G02B 5/208: {for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation}
- G02B 13/146: {with corrections for use in multiple wavelength bands, such as infrared and visible light, e.g. FLIR systems}
- G02B 15/142: {having two groups only}
- G02B 15/1425: {the first group being negative}
- G02B 15/20: having an additional movable lens or lens group for varying the objective focal length
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A zoom lens system includes: a first lens group having a negative refractive power; a second lens group having a positive refractive power; and an aperture between the first and second lens groups, wherein the first lens group and the second lens group are sequentially arranged from an object side to an image side, wherein the zoom lens system performs zooming and focusing by moving the second and first lens groups, respectively, along an optical axis, and satisfies 2.5<(fw/ft)×(Tw/Y)<4.5, where fw denotes an entire focal length at a wide-angle end, ft denotes an entire focal length at a telephoto end, and Tw denotes a distance between an image plane and an object side lens surface of a lens closest to the object side of the first lens group at the wide-angle end, and Y denotes a radical axis image height.

## Claims

### Claim 1

A zoom lens system comprising:
a first lens group having a negative refractive power;
a second lens group having a positive refractive power; and
an aperture disposed between the first lens group and the second lens group,
wherein the first lens group and the second lens group are sequentially arranged from an object side to an image side,
wherein the zoom lens system is configured to perform zooming by moving the second lens group along an optical axis, and perform focusing by moving the first lens group along the optical axis, and
wherein the zoom lens system satisfies a conditional expression below:
2.5<(fw/f1)×(Tw/Y)<4.5,
where fw denotes an entire focal length at a wide-angle end, ft denotes an entire focal length at a telephoto end, and Tw denotes a distance between an image plane and an object side lens surface of a lens that is closest to the object side of the first lens group at the wide-angle end, and Y denotes a radical axis image height.

### Claim 2 (depends on 1)

The zoom lens system of claim 1, wherein the zoom lens system satisfies conditional expressions below:
2.5<|f1/fw|<3.0,
0.8<|f1/f2|<1.0, and
3.1<|f2/fw|<3.5,
where f1 denotes a focal length of the first lens group, and f2 denotes a focal length of the second lens group.

### Claim 3 (depends on 1)

The zoom lens system of claim 1, wherein the first lens group comprises:
a first lens having a negative refractive power;
a second lens having a negative refractive power; and
a third lens having a positive refractive power,
wherein the first lens, the second lens, and the third lens are sequentially arranged from the object side to the image side.

### Claim 4 (depends on 3)

The zoom lens system of claim 3, wherein the second lens and the third lens are cemented lenses.

### Claim 5 (depends on 4)

The zoom lens system of claim 4, wherein the zoom lens system satisfies a conditional expressions below:
vd12>65, and
Nd13>1.90,
where vd12 denotes an Abbe number of the second lens, and Nd13 denotes a refractive index of the third lens at a d-line.

### Claim 6 (depends on 1)

The zoom lens system of claim 1, wherein the second lens group comprises:
a fourth lens, a fifth lens, and a sixth lens each having a positive refractive power;
a seventh lens having a negative refractive power; and
an eighth lens and a ninth lens each having a positive refractive power,
wherein the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are sequentially arranged from the object side to the image side.

### Claim 7 (depends on 6)

The zoom lens system of claim 6, wherein the fourth lens comprises at least one aspherical lens,
wherein the zoom lens system satisfies a conditional expression below:
vd24>60,
where vd24 denotes an Abbe number of the fourth lens.

### Claim 8 (depends on 6)

The zoom lens system of claim 6, wherein the sixth lens, the seventh lens, and the eighth lens are triple cemented lenses.

### Claim 9 (depends on 8)

The zoom lens system of claim 8, wherein the zoom lens system satisfies a conditional expression below:
3.5<|(vd28−vd27)|/vd26<5.0,
where vd26, vd27, and vd28 respectively denote Abbe numbers of the sixth lens, the seventh lens, and the eighth lens.

### Claim 10 (depends on 8)

The zoom lens system of claim 8, wherein the zoom lens system satisfies a conditional expression below:
vd26<vd27<vd28,
where vd26, vd27, and vd28 respectively denote Abbe numbers of the sixth lens, the seventh lens, and the eighth lens.

### Claim 11 (depends on 1)

The zoom lens system of claim 1, further comprising a near infrared light blocking filter between the first lens group and the second lens group.

### Claim 12

A zoom lens system comprising:
a first lens group having a negative refractive power;
a second lens group having a positive refractive power; and
an aperture disposed between the first lens group and the second lens group,
wherein the first lens group and the second lens group are sequentially arranged from an object side to an image side,
wherein the zoom lens system is configured to perform zooming by moving the second lens group along an optical axis and perform focusing by moving the first lens group along the optical axis,
wherein the second lens group comprises:
a fourth lens, a fifth lens, and a sixth lens each having a positive refractive power;
a seventh lens having a negative refractive power; and
an eighth lens and a ninth lens each having a positive refractive power,
wherein the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are sequentially arranged from the object side to the image side,
wherein the zoom lens system satisfies a conditional expression below:
3.5<|(vd28−vd27)|/vd26<5.0,
where vd26, vd27, and vd28 respectively denote Abbe numbers of the sixth lens, the seventh lens, and the eighth lens.

### Claim 13 (depends on 12)

The zoom lens system of claim 12, wherein the sixth lens, the seventh lens, and the eighth lens are cemented lenses.

### Claim 14 (depends on 13)

The zoom lens system of claim 13, wherein the zoom lens system satisfies a conditional expression below:
vd26<vd27<vd28,
where vd26, vd27, and vd28 respectively denote Abbe numbers of the sixth lens, the seventh lens, and the eighth lens.

### Claim 15 (depends on 12)

The zoom lens system of claim 12, wherein the fourth lens comprises at least one aspherical lens, and
wherein the zoom lens system satisfies a conditional expression below:
vd24>60,
where vd24 denotes an Abbe number of the fourth lens.

### Claim 16 (depends on 12)

The zoom lens system of claim 12, wherein the zoom lens system satisfies a conditional expression below:
2.5<(fw/f1)×(Tw/Y)<4.5,
where fw denotes an entire focal length at a wide-angle end, ft denotes an entire focal length at a telephoto end, and Tw denotes a distance between an image plane and an object side lens surface of a lens that is closest to the object side of the first lens group at a wide-angle end, and Y denotes a radical axis image height.

### Claim 17 (depends on 12)

The zoom lens system of claim 12, wherein the zoom lens system satisfies conditional expressions below:
2.5<|f1/fw|<3.0,
0.8<|f1/f2|<1.0, and
3.1<|f2/fw|<3.5,
where f1 denotes a focal length of the first lens group, and f2 denotes a focal length of the second lens group.

### Claim 18 (depends on 12)

The zoom lens system of claim 12, wherein the first lens group comprises:
a first lens having a negative refractive power;
a second lens having a negative refractive power; and
a third lens having a positive refractive power,
wherein the first lens, the second lens, and the third lens are sequentially arranged from the object side to the image side, and the second lens and the third lens are cemented lenses.

### Claim 19 (depends on 18)

The zoom lens system of claim 18, wherein the zoom lens system satisfies conditional expressions below:
vd12>65, and
Nd13>1.90,
where vd12 denotes an Abbe number of the second lens, and Nd13 denotes a refractive index of the third lens at a d-line.

### Claim 20 (depends on 11)

The zoom lens system of claim 11, further comprising a near infrared light blocking filter between the first lens group and the second lens group.