Patent ID: 6907058
Filing Date: 2005-06-14
Classification: G01J,H01S

Abstract:
1. A beam parameter monitoring unit for coupling with a molecular fluorine (F 2 ) or ArF laser resonator that produces an output beam having a wavelength below 200 nm, comprising: an uncoated beam splitter formed of substantially material transparent to radiation having said wavelength below 200 nm disposed to reflect a portion of the radiation in the output beam; a detector for measuring at least one optical parameter of the output beam portion reflected by the uncoated beam splitter; and a beam path enclosure containing said uncoated beam splitter and having an interior prepared such that an optical path of said beam portion through said enclosure from said laser resonator to said detector via said reflection by said beam splitter is substantially free of photoabsorbing species that substantially photoabsorb radiation of said wavelength below 200 nm so that the beam portion reflected by said beam splitter reaches said detector without substantial attenuation from said photoabsorbing species.