LENS MODULE COMPRISING AT LEAST ONE REPLACEABLE OPTICAL ELEMENT

摘要

Disclosed is a lens module (7), especially a projection lens for semiconductor lithography, comprising at least one replaceable optical element (9) that is disposed in a lens housing (12). At least one gas exchange device (15) is positioned in an area of the replaceable optical element (9) in such a way that a receiving zone (10') for the replaceable optical element (9) can be flushed when the optical element (9) is replaced.