Illumination system and lithographic apparatus

摘要

An illumination system comprising a polarization member which comprises first and second polarization modifiers each connected to an actuator configured to move a respective polarization modifier into at least partial intersection with a radiation beam such that the polarization modifier applies a modified polarization to at least part of the radiation beam, and an array of individually controllable reflective elements which is positioned to receive the radiation beam after it has passed the polarization member, the illumination system further comprising a controller capable of controlling the actuators such that the first and second polarization modifiers intersect with different portions of the radiation beam.