Patent ID: 8004650

Claim:
A method of irradiating a layer including: directing and focusing a radiation beam to a spot on said layer by means of at least one optical element; causing relative movement of the layer relative to said at least one optical element so that, successively, different portions of the layer are irradiated and an interspace between a surface of said at least one optical element nearest to said layer is maintained; and maintaining at least a portion of said interspace through which said radiation irradiates said spot on said layer filled with a liquid, the liquid being supplied via a supply conduit and flowing out of an outflow opening; wherein the outflow opening via which the liquid flows out onto the layer is provided in the form of at least one canal that includes an elongated open portion that opens towards said layer, said canal distributing supplied liquid longitudinally along said canal and said elongated open portion of said canal dispensing distributed liquid towards said layer, wherein at least a portion of said liquid fills up a recess through which said radiation irradiates said spot.