Patent ID: 7747127

Claim:
An optical member comprising: a plurality of mutually stuck optical members comprising fluorite (CaF 2 ) and synthetic quartz (SiO 2 ) for use in an ultraviolet region having wavelengths of 100-200 nm; a fluorine-based organic compound provided between the optical members wherein the fluorine-based organic compound is selected from the group consisting of: where m means one or more, n means ten or more, p means one or more and q means one or more, and an adhesive fluorine resin for adhesively sealing a periphery of the fluorine-based organic compound at a periphery of the optical members, where the adhesive fluorine resin has an optical thickness of 10 μm, and a deterioration by UV absorption can be avoided when the optical member is irradiated with a KrF laser of a deep UV wavelength of 248 nm at an output of 3W/cm 2 for 148 hours.