Disclosed is a system configured to project a beam of radiation onto a target portion of a substrate within a lithographic apparatus. The system comprises a mirror (510) having an actuator (500) for positioning the mirror and/or configuring the shape of the mirror, the actuator also providing active damping to the mirror, and a controller (515a, 515b) for generating actuator control signals for control of said actuator(s). A first coordinate system is used for control of said actuator(s) when positioning said mirror and/or configuring the shape of said mirror and a second coordinate system is used for control of said actuator(s) when providing active damping to said mirror.