Abstract: A field facet system for a lithography apparatus comprises: an optical element comprising a base body and an elastically deformable facet portion connected to the base body and having a light-reflecting optically active surface; and a plurality of actuating elements for deforming the facet portion to change a radius of curvature of the optically active surface. The actuating elements are operatively connected to the facet portion to isolate a heat induced deflection of the actuating elements from the facet portion so that the radius of curvature is not affected by the heat-induced deflection of the actuating elements.

Abstract: A field facet system for a lithography apparatus comprises: an optical element which comprises an elastically deformable facet portion having a light-reflecting optically active surface; and at least one actuating element for introducing a bending moment into the facet portion to deform the facet portion to change a radius of curvature of the optically active surface. The facet portion is curved in an arched manner in a plan view of the optically active surface. The rigidity of the facet portion as viewed along a longitudinal direction of the facet portion is variable so that a normal vector oriented perpendicularly to the optically active surface tilts exclusively about a spatial direction when the bending moment is introduced into the facet portion.

Abstract: A field facet for a field facet mirror of a projection exposure apparatus has a reflection surface spanned by two field facet coordinates. An actuator device having at least two independently controllable actuator units serves to deform the reflection surface in at least two independent deformation degrees of freedom. A first of the deformation degrees of freedom brings about a change in a curvature of the reflection surface along a primary curvature coordinate which coincides with one of the field facet coordinates. A second of the deformation degrees of freedom brings about a change in a torsion of the reflection surface about the primary curvature coordinate. This can yield a field facet, the imaging performance of which is optimized, for example adapted to different illumination channel assignments within the projection exposure apparatus.