Ultraviolet polarization beam splitter for microlithography

Abstract

The present invention provides an ultraviolet (UV) polarizing beam splitter cube. The UV polarizing beam splitter cube is transmissive to light at wavelengths equal to or less than 170 nm and can image, at high quality, light incident over a wide range of angles and including a numeric aperture greater than 0.6. The UV polarizing beam splitter cube comprises a pair of prisms that are made of at least a fluoride material, and a coating interface having at least one layer of a thin film fluoride material. Alternating layers of thin film fluoride materials can comprise a first fluoride material having a first refractive index and a second fluoride material having a second refractive index. The first and second fluoride materials form a stack of fluoride materials having relatively high and low refractive indices such that the coating interface separates UV light into two polarized states.

Dependencies are inferred from the claim text.