Patent ID: 6210865
Filing Date: 2001-04-03
Classification: G03F,G21K,Y10S

Abstract:
A condenser system for use with a ringfield camera to collect and image radiation to a mask comprising:a small compact source of radiation;collector mirrors comprising at least two substantially equal radial segments of a parent aspheric mirror, each having one focus at the radiation source and a curved line focus filling the object field of the camera at the radius of the ringfield and each producing a beam of radiation; anda corresponding number of sets of correcting mirror means which are capable of translation or rotation, or both, such that all of the beams of radiation pass through the entrance pupil of the camera and form a coincident arc image at the ringfield radius, wherein at least one of the correcting mirrors of each set, or a mirror that is common to said sets of mirrors, from which the radiation emanates, is a concave relay mirror that is positioned to shape a beam segment having a chord angle of about 25 to 85 degrees into a second beam segment having a chord angle of about 0 to 60 degrees, wherein the distance from the collector mirrors to the concave relay mirror is equal to 3 to 10 times the distance from the concave relay mirror to the mask.