Objective, particularly a projection objective for use in semiconductor lithography

摘要

The invention relates to an objective, particularly a projection objective for use in semiconductor lithography, comprising optical elements such as lenses ( 16 ) and mirrors ( 11 a). According to the invention, at least a portion of the optical elements ( 16, 11 a) is provided with a reflective surface outside of the optically active area serving as the reference surface ( 12 ) for a the optical element inside the objective ( 8 ).