| CPC G03B 21/28 (2013.01) [G02B 17/0816 (2013.01); G03B 21/2066 (2013.01)] | 17 Claims |
|
1. A projection system comprising:
a first optical system; and
a second optical system including an optical element and disposed on an enlargement side of the first optical system, wherein:
the optical element has a first transmissive surface, a first reflection surface disposed on the enlargement side of the first transmissive surface, a second reflection surface disposed on the enlargement side of the first reflection surface, and a second transmissive surface disposed on the enlargement side of the second reflection surface,
the second reflection surface has a concave shape,
a first optical axis of the first optical system and a second optical axis of the second reflection surface intersect each other,
the first transmissive surface and the first reflection surface are located on one side of the first optical axis,
the second reflection surface is located on other side of the first optical axis,
the optical element includes only two reflection surfaces and only two transmissive surfaces, which are the first transmissive surface, the first reflection surface, the second reflection surface and the second transmissive surface with the first reflection surface and the second reflection surface being the only reflection surfaces along an optical path between the first transmissive surface and the second transmissive surface,
the first reflection surface reflects a light flux passing through the first transmissive surface in a direction that intersects the first optical axis,
the first reflection surface reflects by 90° the light flux passing through the first transmissive surface, and
the first reflection surface is a flat mirror.
|