Lithographic apparatus and device manufacturing method

摘要

A lithographic apparatus comprising a radiation system (IL) for providing a projection beam of radiation; a support structure (MT) for supporting patterning means (MA), the patterning means serving to impart the projection beam with a pattern in its cross-section; a substrate table (WT) for holding a substrate (W); and a projection system (PL) for projecting the patterned beam onto a target portion of the substrate. According to the invention the apparatus further comprises a source (IRS) for providing infrared radiation into a measurement zone (1) within said lithographic apparatus, and a detector (2) for receiving the infrared radiation from the source after having passed through said measurement zone and for outputting a signal indicative of the presence of a gas present within the measurement zone. <IMAGE>