Patent ID: 7358507

Claim:
A method of irradiating a layer ( 3 ) including: directing and focusing a radiation beam ( 7 ) to a spot ( 11 ) on said layer ( 3 ) by means of at least one optical element ( 59 ); causing relative movement of the layer ( 3 ) relative to said at least one optical element ( 59 ) so that, successively, different portions of the layer ( 3 ) are irradiated and an interspace ( 53 ) between a surface of said at least one optical element ( 59 ) nearest to said layer ( 3 ) is maintained; and maintaining at least a portion of said interspace ( 53 ) through which said radiation irradiates said spot ( 11 ) on said layer ( 3 ) filled with a liquid ( 91 ) supplied via a supply conduit; characterized by directing gas ( 71 - 73 ) to said layer ( 3 ); and removing supplied liquid ( 91 ) from said layer ( 3 ) in the vicinity of a flow of said gas ( 71 - 73 ).