The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 11, 2005
Filed:
Dec. 17, 2003
Michael Gerhard, Aalen, DE;
Daniel Krähmer, Aalen, DE;
Michael Gerhard, Aalen, DE;
Daniel Krähmer, Aalen, DE;
Carl Zeiss SMT AG, Oberkochen, DE;
Abstract
An objective (), in particular for a microlithography projection apparatus, has lenses or lens parts falling into at least two groups. The first group () is made of a first crystalline material and the second group () is made of a second crystalline material. In the first group (), an outermost aperture ray () is subject to a first optical path difference between two mutually orthogonal states of linear polarization; and the same outermost aperture ray is subject to a second optical path difference in the second group (). The two different crystalline materials are selected so that the first and second optical path difference approximately compensate each other. A suitable selection consists of calcium fluoride for the first and barium fluoride for the second crystalline material.