Lithographic apparatus and device manufacturing method

A lithographic apparatus comprising:

• a projection system configured to project a patterned radiation beam onto a target portion of a substrate, the projection system comprising two optical elements at least partly determining an optical path of the projection system, a position of a first of the optical elements being controllable by a control loop, and
• a feed forward controller having a feed forward control input operationally coupled to a signal in the control loop of the first of the two optical elements, and a feed forward control output operationally connected to an actuator to affect a position of the second of the optical elements based on the signal of the control loop of the first of the optical elements.

A device manufacturing method comprising:

• projecting a patterned beam of radiation onto a target portion of a substrate via a projection system, and
• controlling a position of a movable optical element of the projection system so as to control a position of the projected patterned beam of radiation.

A device manufacturing method comprising:

• projecting a beam of radiation onto a target portion of a substrate via a projection system, the projection system comprising two optical elements at least partly determining an optical path of the projection system,
• controlling a position of a first of the optical elements with a control loop, and
• affecting a position of the second of the optical elements based on the signal of the control loop.