Projection System, Lithographic Apparatus, Method of Projecting a Beam of Radiation onto a Target and Device Manufacturing Method

摘要

A projection system (PS) is provided that includes a sensor system (20) that measures at least one parameter that relates to the physical deformation of a frame (10) that supports the optical elements (11) within the projection system (PS), and a control system (30) that, based on the measurements from the sensor system (20), determines an expected deviation of the position of the beam of radiation projected by the projection system (PS) that is caused by the physical deformation of the frame (10).