A projection system for a lithographic apparatus having a plurality of mirror imaging systems. In an embodiment, the mirror imaging systems are arranged in two rows with each row being perpendicular to a scanning direction of the projection system. Each mirror imaging systems has an associated imaging field. The mirror imaging systems are arranged in a manner that precludes gaps between adjacent imaging fields in the scanning direction. Each mirror imaging system includes a concave mirror and a convex mirror arranged concentrically with the concave mirror. The concave mirrors have a first mirror portion and a second mirror portion that are independently movable. In one embodiment, each of the mirror imaging systems has an associated phase, and the mirror imaging systems in one row are positioned 180 degrees out of phase with the mirror imaging systems in the other row.