Illumination system that suppresses debris from a light source

摘要

There is provided an illumination system for wavelengths of <=193 nm. The illumination system includes an object plane, a plane conjugated to the object plane, a first collector between the object plane and the conjugated plane, and a second collector after the conjugated plane. The first collector focuses a beam bundle of rays from the object plane in the conjugated plane. At least one of the first and second collectors includes a mirror shell. The rays strike the mirror shell at an angle of incidence of less than 20° relative to a surface tangent of the mirror shell.