Lithographic apparatus and device manufacturing method

摘要

A reaction mass 14; 54; 64 and an actuator 15; 55; 65 are used to reduce unwanted vibrations of an optical element 10; 50; 60 in the projection system of a lithographic projection apparatus. The reaction mass 14; 54; 64 may be mechanically connected only to the optical element 50; 60 or may be compliantly mounted to the projection system frame 11.