Patent ID: 7591560
Filing Date: 2009-09-22
Classification: G02B

Abstract:
1. A reflection optical system placed between two image surfaces one of which is an enlargement side image surface and the other of which is a reduction side image surface, and forming no intermediate image between the two image surfaces, said reflection optical system comprising: a first mirror; a second mirror; and a third mirror; wherein among optical surfaces of the reflection optical system, curved surfaces are only three reflection surfaces of the first mirror, the second mirror and the third mirror in the order from the side of said enlargement side image surface, and the following conditional expressions (1) and (2) are met: where θL: minimum angle which a light beam passing through the center of a reduction side pupil forms with respect to the enlargement side image surface; and θUL: difference between maximum and minimum angles which a light beam passing through the center of a reduction side pupil forms with respect to the enlargement side image surface.