US 2026/0083307 A1Published application

Optical system, imaging device, and endoscope system

AssigneeSony Group Corporation

InventorNaomichi KIKUCHI

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Abstract

An optical system includes an image forming optical system with a first and a second lens group, and forms an image of light from a subject on each of a visible light imaging element and an infrared light imaging element. The system also includes a separation optical system that separates an optical path of light passing through the image forming optical system into at least two optical paths. The first lens group includes a plurality of cemented lenses formed by bonding a lens having positive refractive power and a lens having negative refractive power, in which when αp is an average linear expansion coefficient of the lens having positive refractive power at 100° C. to 300° C. and αn is an average linear expansion coefficient of the lens having negative refractive power at 100° C. to 300° C., the following conditional formula |1−αp/αn|<0.2 is satisfied.

Claims13

Dependent claims

An optical system comprising:

an image forming optical system that includes a first lens group having positive refractive power and a second lens group configured to be movable in an optical axis direction according to a distance to a subject, and forms an image of light from the subject on each of a visible light imaging element and an infrared light imaging element;
an aperture diaphragm arranged between the subject and the image forming optical system;
and
a separation optical system that separates an optical path of light passing through the image forming optical system into an optical path of visible light to the visible light imaging element and an optical path of infrared light to the infrared light imaging element,
wherein when BF (air) is an air conversion distance from a vertex on a side of the separation optical system of a lens at an end portion on a side of the separation optical system among lenses having refractive power of the image forming optical system to the visible light imaging element, and L is a distance on an optical axis from the aperture diaphragm to the visible light imaging element, the following conditional formula
BF
⁢
(
air
)
/
L
>
0.3
is satisfied,
the first lens group includes a plurality of cemented lenses formed by bonding a lens having positive refractive power and a lens having negative refractive power, and
in the plurality of cemented lenses, when αp is an average linear expansion coefficient at 100° C. to 300° C. in the lens having the positive refractive power, and αn is an average linear expansion coefficient at 100° C. to 300° C. in the lens having the negative refractive power, the following conditional formula
❘
"\[LeftBracketingBar]"
1
-
α
⁢
p
/
α
⁢
n
❘
"\[RightBracketingBar]"
<
0.
2
is satisfied.

31 more elements

An endoscope system comprising:

a rigid endoscope unit that generates a visible light image and an infrared light image of a subject;
a visible light imaging element;
an infrared light imaging element;
and
an optical system connected to the rigid endoscope unit to form the visible light image on the visible light imaging element and form the infrared light image on the infrared light imaging element,
the optical system including:
an image forming optical system that includes a first lens group having positive refractive power and a second lens group configured to be movable in an optical axis direction according to a distance to a subject, and forms an image of light from the subject on each of the visible light imaging element and the infrared light imaging element;
an aperture diaphragm arranged between the subject and the image forming optical system;
and
a separation optical system that separates an optical path of light passing through the image forming optical system into an optical path of visible light to the visible light imaging element and an optical path of infrared light to the infrared light imaging element,
wherein when BF (air) is an air conversion distance from a vertex on a side of the separation optical system of a lens at an end portion on a side of the separation optical system among lenses having refractive power of the image forming optical system to the visible light imaging element, and L is a distance on an optical axis from the aperture diaphragm to the visible light imaging element, the following conditional formula
BF
⁢
(
air
)
/
L
>
0.3
is satisfied,
the first lens group includes a plurality of cemented lenses formed by bonding a lens having positive refractive power and a lens having negative refractive power, and
in the plurality of cemented lenses, when αp is an average linear expansion coefficient at 100° C. to 300° C. in the lens having the positive refractive power, and αn is an average linear expansion coefficient at 100° C. to 300° C. in the lens having the negative refractive power, the following conditional formula
❘
"\[LeftBracketingBar]"
1
-
α
⁢
p
/
α
⁢
n
❘
"\[RightBracketingBar]"
<
0.
2
is satisfied.

37 more elements

Dependencies are inferred from the claim text.