Patent ID: 8368039
Filing Date: 2013-02-05
Classification: H05G

Abstract:
1. An apparatus comprising: a chamber defining an internal surface, the chamber housing a collector mirror having a shape that defines a primary focus at a target location and a secondary focus at an intermediate location; a light source configured to produce an amplified light beam along a beam path through an aperture of the collector mirror to irradiate a target material in the chamber at the target location and to generate extreme ultraviolet light, the light source including a gain medium for amplifying light of a source wavelength; and a subsystem overlying at least a portion of the internal surface of the chamber, the subsystem including a plurality of annular features, each annular feature having a central open region that permits generated extreme ultraviolet light to pass through to the intermediate focus and each annular feature extends from a chamber wall into a path of the amplified light beam, wherein the subsystem is configured to reduce a flow of the amplified light beam at the source wavelength from the chamber internal surface back along the beam path toward the light source.