POSITIONIERVORRICHTUNG MIT EINER SCHEIBE MIT EINEM GESCHLOSSENEN GASSYSTEM ZUR ERZEUGUNG EINES FLUIDKISSENS

A positioning device of the type described characterised by the incorporation of the puck into a closed circuit gas system from which the puck establishes the flow of fluid to provide the fluid cushion. Typically the positioning device is characterised by the provision of a heat transfer mechanism incorporated in the closed circuit to provide for heat exchange between the heat transfer mechanism and gas flowing around the system. The puck is coupled to a lens and a mask to provide for close following of a surface of a work-piece so as to keep a magnified image of the mask stable; the combination of puck, lens and mask forming a unit counterbalanced by a counterweight acting to provide for adjustment of focus of the laser beam relative to the surface of the work-piece.