Lithographic device

A lithographic device has a radiation system for supplying a projection beam of radiation; a mask table provided with a mask holder for holding a mask; a substrate table provided with a substrate holder for holding a substrate; and a projection system for imaging an irradiated portion of the mask onto a target portion of the substrate. The projection system is separated from the table by an intervening space which can be at least partially evacuated and which is delimited at the location of the projection system by a mirror from which the employed radiation is directed toward the substrate table. The intervening space contains a hollow tube located between the solid surface and the substrate table and situated around the path of radiation, the form and size of the tube being such that radiation focused by the de Jager et al. projection system onto the substrate table does not intercept a wall of the hollow tube. A gas flushing unit is provided for continually flushing the inside of the hollow tube with a flow of gas.