ILLUMINATION SYSTEM, LITHOGRAPHIC APPARATUS AND METHOD OF ADJUSTING AN ILLUMINATION MODE

摘要

An illumination system is disclosed that has a plurality of moveable reflective elements (22a, 22b, 22c) and associated actuators which may be configured to form an illumination mode. One or more of the actuators is arranged to move between first, second and third positions, and so move an associated moveable reflective element (22a, 22b, 22c) between first, second and third orientations, the first and second orientations being such that radiation reflected from the moveable reflective element (22a, 22b, 22c) forms part of the illumination mode, and the third orientation being such that radiation reflected from the moveable reflective element does not form part of the illumination mode.