(19)

(11)

EP 1 492 994 A2

(12)

(88) Date of publication A3: 18.12.2003 (43) Date of publication: 05.01.2005 Bulletin 2005/01 (21) Application number: 03714507.5 (22) Date of filing: 04.04.2003

(51) International Patent Classification (IPC)7: G01B 9/02 (86) International application number: PCT/US2003/010212 (87) International publication number: WO 2003/087710 (23.10.2003 Gazette 2003/43)

(84) Designated Contracting States: AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT RO SE SI SK TR (30) Priority: 09.04.2002 US 371172 P 13.08.2002 US 217531 (71) Applicant: Zygo Corporation Middlefield, CT 06455-0448 (US)	(72) Inventor: HILL, Henry, Allen Tucson, AZ 85716 (US) (74) Representative: Cole, David John et al 46 Kirkhill Gardens,West Greenlees Estate Cambuslang,Glasgow G72 8EZ Cambuslang,Glasgow G72 8EZ (GB)