Optical system, image projection apparatus, and imaging apparatus

Patent metadata

Field	Value
Publication number	US-2026050148-A1
Application number	US-202519357499-A
Country	US
Kind code	A1
Filing date	Oct 14, 2025
Priority date	Jun 13, 2023
Publication date	Feb 19, 2026
Grant date	—

Abstract

An optical system has a reduction conjugate point on a reduction side and a magnification conjugate point on a magnification side, and has an intermediate imaging position conjugate with each of these points inside. The optical system includes: a first sub-optical system including a plurality of lenses arranged along an optical axis, and an aperture stop; and a second sub-optical system including a prism. The prism includes a first transmission surface located on the reduction side; a second transmission surface located on the magnification side; and a reflection surface group including a plurality of reflection surfaces having a first reflection surface and a second reflection surface located between the first transmission surface and the second transmission surface in a Y direction perpendicular to the Z direction, and located in order of an optical path from the first transmission surface to the second transmission surface.

First claim

What is claimed is:

1 . An optical system having a reduction conjugate point on a reduction side and a magnification conjugate point on a magnification side, and having an intermediate imaging position conjugate with each of the reduction conjugate point and the magnification conjugate point inside, the optical system comprising:
a first sub-optical system including a plurality of lenses arranged along an optical axis in a Z direction, and an aperture stop between two lenses among the plurality of lenses; and a second sub-optical system disposed closer to the magnification side than the first sub-optical system and including a prism having a plurality of optical surfaces, wherein the prism includes: as the plurality of optical surfaces,
a first transmission surface located on the reduction side;
a second transmission surface located on the magnification side; and
a reflection surface group including a plurality of reflection surfaces having a first reflection surface and a second reflection surface located between the first transmission surface and the second transmission surface in a Y direction perpendicular to the Z direction, and located in order of an optical path from the first transmission surface to the second transmission surface,
a light flux travels in a YZ surface including the Z direction and the Y direction inside the prism, the intermediate imaging position of a first light flux closest to the optical axis is disposed between the first transmission surface and the first reflection surface, the second transmission surface has a shape with a convex surface facing the magnification side, and a reflection surface located on a most magnification side in the reflection surface group has a convex shape with respect to the inside of the prism, the first reflection surface has stronger positive power than the second reflection surface, and on the YZ surface with respect to an effective region of the plurality of optical surfaces, a distance FL 2 is smaller than a distance FL 1 in the distance FL 1 between a point of the first reflection surface farthest from a perpendicular line of the optical axis passing through a surface vertex of an optical surface on a most magnification side of the first sub-optical system and the perpendicular line and the distance FL 2 between a point of the second transmission surface farthest from the perpendicular line and the perpendicular line.

2 . The optical system according to claim 1 , wherein
on the YZ surface, in a distance PL 1 parallel to the Z direction between a point of the first transmission surface closest to the perpendicular line and a point of the first reflection surface farthest from the perpendicular line, and in a distance PL 2 parallel to the Z direction between a point of the second reflection surface closest to the perpendicular line and a point of the second transmission surface farthest from the perpendicular line, the distance PL 2 is smaller than the distance PL 1 .

3 . The optical system according to claim 1 , wherein in a case where a YZ coordinate (yt1, zt1) of a first point through which a principal ray of the first light flux passes on the first transmission surface is compared with a YZ coordinate (yr2, zr2) of a second point from which the principal ray of the first light flux reflects on the second reflection surface, a Z coordinate interval |zr2−zt1| is smaller than a Y coordinate interval |yr2−yt1|.

4 . The optical system according to claim 2 , satisfying the following formulae (1) and (2):

0.5
<

PL
⁢
2
/
PL
⁢
1

<
0.8

(
1
)

❘
"\[LeftBracketingBar]"

(

zr
⁢
2

-

zt
⁢
1

)

/

(

yr
⁢

2

-

yt
⁢
1

)

❘
"\[RightBracketingBar]"

<

1.
.

(
2
)

5 . The optical system according to claim 1 , satisfying the following formula (3):

0.5
<

α
⁢
r
⁢
2

<
3.

(
3
)

wherein,
αr2 is an angle (unit: °) formed between a normal line at a position of the second reflection surface on which a principal ray of the first light flux is made incident and a normal line of a conjugate surface including the reduction conjugate point.

6 . The optical system according to claim 1 , satisfying the following formula (4):

0.
<

rt
⁢
1
⁢
x
/
rt
⁢
1
⁢
y

<
0.8

(

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Imaoka Takuya
• Kobayashi Yasushi

Classifications

• G02B17/0856

  comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors · CPC title

• G03B21/28

  Reflectors in projection beam {(in illumination beam G03B21/2066)} · CPC title

• G02B27/0972

  Prisms (prisms per se G02B5/04) · CPC title

• G02B13/18 Primary

  with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)} · CPC title

• G03B21/14

  Details · CPC title