Patent ID: 8657450
Filing Date: 2014-02-25
Classification: G03B

Abstract:
1. A projection optical system which is arranged to cause a number of light beams output from an image forming element on a first conjugate surface to slantingly enter a second conjugate surface and project an enlarged image of an image formed by the image forming element, on the second conjugate surface, the projection optical system comprising: a first optical system disposed on a first optical path between the image forming element and the second conjugate surface and including a refracting optical system; a second optical system disposed on the first optical path at a downstream position of the first optical system and including a reflection surface having a positive power; and first and second reflection mirrors disposed in this order on a second optical path between the image forming element and the reflection surface to reflect the light beams along the second optical path, wherein the first and second reflection mirrors are arranged so that a direction of an optical path of the light beams from the second reflection mirror to the reflection surface contains a component of a direction that is opposite to a predetermined direction from the image forming element to the first optical system, and a projection image of the image forming element on the second conjugate surface, a projection of the reflection surface onto the second conjugate surface, and a projection of the image forming element onto the second conjugate surface are arrayed in this order on the second conjugate surface.