Patent ID: 7130017

Claim:
A projection exposure apparatus, comprising: an illumination system; a reticle; a projection objective; and an image plane, wherein interstitial spaces between the individual elements of the apparatus are open to ambient space; and a gas purge device arranged in at least one of the interstitial spaces for carrying a stream of one of a noble gas and nitrogen, wherein the gas purge device is of a shape and size so that one or more interstitial spaces are at least to a large extent sealed off from the ambient space surrounding the projection exposure apparatus, wherein the gas purge device is equipped with at least one gas inflow device that is configured as a hollow orifice passage and with at least one gas outflow device, wherein the hollow orifice passage is ring-shaped and extends circumferentially about an optical axis of the apparatus so as to achieve a laminar inflow stream of the nitrogen or the noble gas into the gas purge device, wherein the gas purge device includes a compartment extending between the ring-shaped passage to permit the gas to flow in a transverse direction relative to the inflow into the gas purge device.