US 2003/0227693 A1 · Projection optical system and projection exposure device which uses same

Abstract

A projection optical system that is telecentric or very nearly telecentric on both sides is formed of four positive lens groups with a central diaphragm for achieving at least very nearly unity magnification. The second and third lens groups are movable along the optical axis of the projection optical system, preferably at the same rate and in the same direction, in order to vary the magnification of the projection optical system. The range of movement of the second and third lens groups includes a position where the first and second lens groups together are a mirror image about the plane of the diaphragm of the third and fourth lens groups together. A projection exposure device uses the projection optical system to form an image of an illuminating beam modulated by a mask pattern on a workpiece. An image magnification detector controls movement of the second and third lens groups.

Claims20

Dependent claims

A projection optical system having an optical axis and comprised of, in order:

a first lens group;
a second lens group;
a diaphragm;
a third lens group;
and
a fourth lens group;
wherein
said second lens group and said third lens group are movable along the optical axis of the projection optical system in order to vary the magnification of the projection optical system;
the range of movement of said second lens group and said third lens group along the optical axis includes a position where the first lens group and the second lens group as a first lens unit and the third lens group and the fourth lens group as a second lens unit are positioned symmetrically on opposite sides of a plane that includes said diaphragm so that the first and second lens units are mirror images of one another with regard to said plane so that the optical projection system achieves at least very nearly unity magnification when said second lens group and said third lens group are at said position;
and
the projection optical system is telecentric or very nearly telecentric on both sides.

8 more elements

Dependencies are inferred from the claim text.

Projection optical system and projection exposure device which uses same

Life of this patent

Projection optical system and projection exposure device which uses same

Life of this patent

Abstract

Claims20