Patent ID: 9075322
Filing Date: 2015-07-07
Classification: G03F

Abstract:
1. A reflective imaging optical system which forms, on a second plane, an image of a predetermined area on a first plane, the reflective imaging optical system comprising: a first reflecting mirror, a second reflecting mirror, a third reflecting mirror, a fourth reflecting mirror, a fifth reflecting mirror, a sixth reflecting mirror, a seventh reflecting mirror and an eighth reflecting mirror which are arranged in an order of reflection from the first plane toward the second plane; and an entrance pupil which is positioned on a side opposite to the reflective imaging optical system with respect to the first plane intervening therebetween; wherein the following condition is fulfilled provided that PD represents a distance along an optical axis between the entrance pupil and the first plane, TT represents a distance along the optical axis between the first plane and the second plane, and R represents an angle of incidence (rad) of a main light beam coming into the first plane: