Projection optical system and projector
A projection optical system capable of performing compact and proximate projection and a projector including the projection optical system. The projection optical system includes a first optical group which is a dioptric system and a second optical group which is a catoptric system. The second optical group includes a first catoptric system to a third catoptric system that have a first reflection surface with a concave surface shape, a second reflection surface with a curved surface shape, and a third reflection surface with a convex surface shape. The first catoptric system to the third catoptric system satisfy Conditional Expression (1) for focal distances. Image light emitted from the first optical group is reflected by the second optical group to be projected to a projection surface.
1. A projection optical system comprising:
a dioptric system including a plurality of lenses and having positive powers and a catoptric system that are installed in order from a reduction side,
wherein the catoptric system includes first, second, and third catoptric systems installed in order from a side of the dioptric system along an optical path of light emitted from the dioptric system,
wherein the first catoptric system includes a first reflection surface that has a concave surface shape,
wherein the second catoptric system includes a second reflection surface that has a curved surface shape,
wherein the third catoptric system includes a third reflection surface that has a convex surface shape,
wherein at least two of the first, second, and third reflection surfaces have an aspherical shape, and
wherein when f1 is a focal distance of the first catoptric system, f2 is a focal distance of the second catoptric system, and f3 is a focal distance of the third catoptric system, f1, f2, and f3 satisfy Conditional Expression (1) below
| f 2|>| f 3|>| f 1| (1).
2. The projection optical system according to claim 1 ,
wherein when F is a focal distance of the whole system and FL is a focal distance of the dioptric system, Conditional Expression (2) below is satisfied
0.05< F/FL< 0.15 (2).
3. The projection optical system according to claim 1 ,
wherein all the plurality of lenses are rotationally symmetric systems.
4. The projection optical system according to claim 3 ,
wherein all surfaces of the plurality of lenses and the first to third catoptric systems are configured with rotationally symmetric surfaces to form a coaxial optical system that has a same optical axis.
5. The projection optical system according to claim 1 ,
wherein the plurality of lenses include a light transmission reflection optical system that has a light transmission region functioning as a part of the dioptric system and a light reflection region functioning as the second reflection surface.
6. The projection optical system according to claim 5 ,
wherein the light transmission reflection optical system is disposed in a most enlargement side in the dioptric system and is fixed in focusing at the time of magnification associated with a change in a projection distance.
7. The projection optical system according to claim 1 ,
wherein the dioptric system includes at least one lens group moved at the time of magnification and is configured to include a 1-1th lens group with a positive power and a 1-2th lens group with a positive power in order from the reduction side using a variable interval on a most reduction side as a boundary, and Conditional Expression (3) below is satisfied when F 1-1 is a focal distance of the 1-1th lens group and F 1-2 is a focal distance of the 1-2th lens group
0.0<| F 1-1 /F 1-2 |<1.0 (3).
8. The projection optical system according to claim 1 ,
wherein a numerical aperture on an object side is equal to or greater than 0.27.
9. The projection optical system according to claim 1 ,
wherein the reduction side is substantially telecentric.
10. The projection optical system according to claim 1 ,
wherein a magnification range is 1.4 times or more.
11. A projector comprising:
a light source;
a light modulation element that modulates light from the light source to form image light; and
the projection optical system according to claim 1 that projects the image light.
12. A projector comprising:
a light source;
a light modulation element that modulates light from the light source to form image light; and
the projection optical system according to claim 2 that projects the image light.
13. A projector comprising:
a light source;
a light modulation element that modulates light from the light source to form image light; and
the projection optical system according to claim 3 that projects the image light.
14. A projector comprising:
a light source;
a light modulation element that modulates light from the light source to form image light; and
the projection optical system according to claim 4 that projects the image light.
15. A projector comprising:
a light source;
a light modulation element that modulates light from the light source to form image light; and
the projection optical system according to claim 5 that projects the image light.
16. A projector comprising:
a light source;
a light modulation element that modulates light from the light source to form image light; and
the projection optical system according to claim 6 that projects the image light.
17. A projector comprising:
a light source;
a light modulation element that modulates light from the light source to form image light; and
the projection optical system according to claim 7 that projects the image light.
18. A projector comprising:
a light source;
a light modulation element that modulates light from the light source to form image light; and
the projection optical system according to claim 8 that projects the image light.
19. A projector comprising:
a light source;
a light modulation element that modulates light from the light source to form image light; and
the projection optical system according to claim 9 that projects the image light.
20. A projector comprising:
a light source;
a light modulation element that modulates light from the light source to form image light; and
the projection optical system according to claim 10 that projects the image light.