# US 2021/0278640 A1 · Set of negative meniscus lenses, wide-angle optical system, image pickup apparatus, and projection apparatus

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- Number: US 2021/0278640 A1
- Document ID: US20210278640A1
- Status: Published application
- Kind: A1
- Application number: 17/329,303
- Filed: 2021-05-25
- Published: 2021-09-09
- Earliest claimed: 2018-11-28
- Assignees: Olympus Corporation
- Applicants: Olympus Corporation
- Inventors: Takayoshi TOGINO
- Web page: https://patentgrep.com/patent/US20210278640A1

## CPC

- G02B 13/06: Panoramic objectives; So-called "sky lenses" {including panoramic objectives having reflecting surfaces}
- G02B 9/60: having five components only
- G02B 9/62: having six components only
- G02B 9/64: having more than six components
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A set of negative meniscus lenses is a set which is to be used for an optical system having an angle of view not smaller than 240°. One negative meniscus lens in the set of negative meniscus lenses is located nearest to an object. The set of negative meniscus lenses has a predetermined lens surface, and the predetermined lens surface is a hemispherical surface or a surface extending beyond hemisphere.

## Claims

### Claim 1

A set of negative meniscus lenses, comprising:
a first meniscus lens; and
a second meniscus lens; wherein
the set of negative meniscus lenses has a predetermined lens surface,
the set of negative meniscus lenses is used for an optical system having an angle of view not smaller than 240°,
one negative meniscus lens in the set of negative meniscus lenses is located nearest to an object,
the predetermined lens surface is a hemispherical surface or a surface extending beyond hemisphere,
the first meniscus lens and the second meniscus lens are adjacent, and
both the first meniscus lens and the second meniscus lens are meniscus lenses having a convex surface directed toward an object side.

### Claim 2 (depends on 1)

The set of negative meniscus lenses according to claim 1, wherein following conditional expressions (1) and (2) are satisfied:
0.9<(RL1o/ndL1)/dL1oi<1.6 (1)
0.4<(RL2o/ndL2)/dL2oi<1.4 (2)
where,
RL1o denotes a radius of curvature of an object-side surface of the first meniscus lens,
RL2o denotes a radius of curvature of an object-side surface of the second meniscus lens,
ndL1 denotes a refractive index for a d-line of the first meniscus lens,
ndL2 denotes a refractive index for a d-line of the second meniscus lens,
dL1oi denotes a distance between a center of curvature of the object-side surface of the first meniscus lens and a center of curvature of an image-side surface of the first meniscus lens, and
dL2oi denotes a distance between a center of curvature of the object-side surface of the second meniscus lens and a center of curvature of an image-side surface of the second meniscus lens.

### Claim 3 (depends on 1)

The set of negative meniscus lenses according to claim 1, wherein following conditional expressions (3) and (4) are satisfied:
1.5<RL1o/RL1i<3.0 (3)
0.2<(DL1+DL12)/RL10<0.7 (4)
where,
RL1o denotes a radius of curvature an object-side surface of the first meniscus lens,
RL1i denotes a radius of curvature of an image-side surface of the first meniscus lens,
DL1 denotes a distance on an optical axis between the object-side surface of the first meniscus lens and the image-side surface of the first meniscus lens, and
DL12 denotes a distance on the optical axis between the image-side surface of the first meniscus lens and an object-side surface of the second meniscus lens.

### Claim 4 (depends on 1)

The set of negative meniscus lenses according to claim 1, wherein following conditional expressions (5), (6), and (7) are satisfied:
0.5<dL1oi/RL1i<1.7 (5)
0.3<dL1iL2o/RL2o<1.1 (6)
0.7<dL2oi/RL2i<6.0 (7)
where,
RL1i denotes a radius of curvature of an image-side surface of the first meniscus lens,
RL2o denotes a radius of curvature of an object-side surface of the second meniscus lens,
RL2i denotes a radius of curvature of an image-side surface of the second meniscus lens,
dL1oi denotes a distance between a center of curvature of an object-side surface of the first meniscus lens and a center of curvature of the image side surface of the first meniscus lens,
dL1iL2o denotes a distance between a center of curvature of the image side surface of the first meniscus lens and a center of curvature of the object-side surface of the second meniscus lens, and
dL2oi denotes a distance between the center of curvature of the object-side surface of the second meniscus lens a center of curvature of the image-side surface of the second meniscus lens.

### Claim 5 (depends on 1)

The set of negative meniscus lenses according to claim 1, wherein the predetermined lens surface is a surface which is convex on the object side.

### Claim 6 (depends on 1)

A wide-angle optical system having an angle of view not smaller than 240°, comprising:
a set of negative meniscus lenses according to claim 1; and
a lens which is disposed on an image side of the set of negative meniscus lenses.

### Claim 7 (depends on 6)

An image pickup apparatus comprising:
a wide-angle optical system according to claim 6; and
an image sensor which is disposed on an image side of the wide-angle optical system, wherein
the image sensor has an image pickup surface, and converts an image formed on the image pickup surface by the wide-angle optical system to an electric signal.

### Claim 8 (depends on 6)

A projection apparatus comprising:
a wide-angle optical system according to claim 6; and
a display element which is disposed on an image side of the wide-angle optical system, wherein
the display element has a display surface, and
an image displayed on the display surface is projected on an object side by the wide-angle optical system.