Abstract: An optical system having an input surface configured to receive an input optical signal having a polarization, and a polarization changer comprising the input surface and configured to generate two orthogonal polarization components from the input optical signal. The polarization changer also changes a direction of the polarization of the input optical signal in a controlled manner while maintaining coherence of the two orthogonal polarization components in order to reduce stimulated Brillion scattering.

Abstract: A method and apparatus to eliminate contaminants in a lithography process for fabrication of integrated circuit devices. The method includes depositing a photoresist material on surface of a semiconductor substrate. A purge gas flow is provided proximate to an optical element to prevent a vapor from the exposed photoresist material from coming into contact with the optical element. In one embodiment, the purge gas flows into a perforated and open ended enclosure in which the optical element is provided in the form of a lens. One open end of the enclosure is coupled to the lens and the other open end is positioned above the surface of the semiconductor substrate. Perforation of the enclosure facilitates movement of purge gas thereto, eliminating contact with the vapor from the developed resist and unwanted deposition of a solid contamination on the lens.