In a solid immersion lithography apparatus, the final element of the projection system is maintained at a distance of less than about 50 nm from the substrate by an actuator system. The final element may be formed as two parts, with a fluid, e.g. a liquid, confined between them. The actuator system may be controlled relative to a reference frame, which may be supported by a bearing. Backscatter detection can be used to determine if the distance between the final element and the substrate is too large. A cleaning device can clean the substrate between exposures.