(19)

(11)

EP 1 864 175 A2

(12)

(88) Date of publication A3: 19.04.2007 (43) Date of publication: 12.12.2007 Bulletin 2007/50 (21) Application number: 06738149.1 (22) Date of filing: 13.03.2006

(51) International Patent Classification (IPC):  G02B 17/00(2006.01) (86) International application number: PCT/US2006/009059 (87) International publication number: WO 2006/107527 (12.10.2006 Gazette 2006/41)

(84) Designated Contracting States: DE FR GB (30) Priority: 31.03.2005 US 667237 P (71) Applicant: KLA-Tencor Technologies Corporation Milpitas, California 95035 (US)	(72) Inventors: SHAFER, David Fairfield, Connecticut 06430 (US) ARMSTRONG, J. Joseph Milpitas, California 95035 (US) CHUANG, Yung-Ho Cupertino, California 95014 (US) (74) Representative: Holmes, Matthew Peter et al MARKS & CLERK, Sussex House, 83-85 Mosley Street Manchester M2 3LG Manchester M2 3LG (GB)