Abstract: A projection system (PS1) for a lithographic apparatus comprises: an optical path (100); a plurality of sensors (S1-S4); one or more actuators (A1-A4); and a controller (CN). The optical path is operable to receive an input radiation beam (Bin) and to project an output radiation beam (Bout) onto a substrate to form an image. The optical path comprises: a plurality of optical elements (M1-M4), the plurality of optical elements comprising: a first set of at least two optical elements (M1, M4) and a second set of at least one optical element (M2, M3). Each sensor is associated with one of the plurality of optical elements and is operable to determine a position of that optical element. Each actuator is associated with one of the second set of optical elements and is operable to adjust that optical element.

Abstract: A lithographic apparatus includes a reflector to redirect a radiation beam, e.g. an EUV beam. The position of the reflector is controlled using a controller and a positioning system. The positioning system includes a non-compensating actuator device and a compensating actuator device to compensate for parasitic forces of the non-compensating actuator device. The positioning system and controller can provide a more accurate position of the reflector, reduce deformation of the reflector and reduce the magnitude of forces transmitting through the reflector.

Abstract: A projection system (PS1) for a lithographic apparatus comprises: an optical path (100); a plurality of sensors (S1-S4); one or more actuators (A1-A4); and a controller (CN). The optical path is operable to receive an input radiation beam (Bin) and to project an output radiation beam (Bout) onto a substrate to form an image. The optical path comprises: a plurality of optical elements (M1-M4), the plurality of optical elements comprising: a first set of at least two optical elements (M1, M4) and a second set of at least one optical element (M2, M3). Each sensor is associated with one of the plurality of optical elements and is operable to determine a position of that optical element. Each actuator is associated with one of the second set of optical elements and is operable to adjust that optical element.

Abstract: A lithographic apparatus comprising a reflector (15) to redirect a radiation beam e.g. an EUV beam. The position of the reflector is controlled using a controller and a positioning system. The positioning system comprises a non-compensating actuator device (300) and a compensating actuator device (200) to compensate for parasitic forces of the non-compensating actuator device. The positioning system and controller can provide a more accurate position of the reflector, reduce deformation of the reflector and reduce the magnitude of forces transmitting through the reflector.

Abstract: A signal-processing device (301) for controlling a focus actuator (309) in an optical disc system (30), wherein the signal processing device (309) generates a focus actuator control signal (CS) to be supplied to the focus actuator (309). The focus actuator control signal (CS) is based on a focus error signal (FE) and a central aperture signal (CA). If the central aperture signal (CA) is equal to or above a certain threshold value the focus actuator control signal will correspond to the focus error signal (FE). However, when the central aperture signal is below the threshold value the focus actuator control signal will have a predefined level. By providing a focus actuator control signal (CS) in accordance herewith it is possible to extend the regions of the focus error signal (FE) in which the relative distance between the focus point and the data layer of the record medium (304) is not correctly represented.

Abstract: A signal-processing device (301) for controlling a focus actuator (309) in an optical disc system (30), wherein the signal processing device (309) generates a focus actuator control signal (CS) to be supplied to the focus actuator (309). The focus actuator control signal (CS) is based on a focus error signal (FE) and a central aperture signal (CA). If the central aperture signal (CA) is equal to or above a certain threshold value the focus actuator control signal will correspond to the focus error signal (FE). However, when the central aperture signal is below the threshold value the focus actuator control signal will have a predefined level. By providing a focus actuator control signal (CS) in accordance herewith it is possible to extend the regions of the focus error signal (FE) in which the relative distance between the focus point and the data layer of the record medium (304) is not correctly represented.