Patent ID: 7190527

Claim:
A refractive projection objective for microlithography with a numerical aperture NA greater than 0.7, consisting of: a first lens group immediately following an object plane of the projection objective and having negative refractive power; a second lens group immediately following the first lens group and having positive refractive power; a third lens group immediately following the second lens group and having negative refractive power for generating a constriction of a light beam passing through the projection objective; a fourth lens group immediately following the third lens group and having positive refractive power; and a fifth lens group immediately following the fourth lens group and having positive refractive power; the projection objective thereby consisting of a first convexity, a second convexity, and a waist arranged between the first and second convexity, wherein the first convexity has a maximum diameter denoted by D1, and the second convexity has a maximum diameter denoted by D2, and 0.8 <D 1 /D 2 <1.1.