Patent ID: 7218453
Filing Date: 2007-05-15
Classification: G02B,G03F

Abstract:
1. A projection system for imaging an object field onto an image field, said projection system comprising: at least two partial objectives; at least one intermediate image field between said partial objectives; and a concave reflector having a concave reflecting surface; wherein said concave reflecting surface satisfies at least one of the following conditions: (a) said concave reflecting surface crosses an optical axis of said projection system proximate along the optical axis to the intermediate image field; or (b) said concave reflecting surface crosses the optical axis of said projection system at a position where the condition |H (c) said concave reflecting surface crosses the optical axis of said projection system at a position where the condition d=y*L is met, with d being an axial distance from said concave reflecting surface to the intermediate image field, and with L being the total geometrical light path travelled by a light beam along the optical axis from the object field to the image field, wherein y ranges from 0 to 0.10.