Catadioptric reduction projection optical system.

摘要

A catadioptric reduction optical system for forming the reduced image of an object includes, a first partial optical system having first reflecting means and first refracting means to condense a light beam from the object and form a reduced primary image, and a second partial optical system having second reflecting means and second refracting means to form a further reduced secondary image from primary image. The first reflecting means has one concave reflecting mirror, the first refracting means has a front lens group G11 of positive refractive power and a rear lens group G12 of negative refractive power both disposed between said object and the concave reflecting mirror. The second reflecting means has one concave reflecting mirror. The second refracting means has a lens group of positive refractive power disposed between the concave reflecting mirror and the secondary mirror. Use: Projector for litographic step in the production of semiconductor devices. <IMAGE>