(19)

(11)

EP 0 261 199 A1

(12)

(43) Date of publication: 30.03.1988 Bulletin 1988/13 (21) Application number: 87902207.0 (22) Date of filing: 27.02.1987

(51) International Patent Classification (IPC):  H01J 35/ 06( . ) H01J 35/ 16( . ) H01J 35/ 12( . ) H01J 35/ 24( . ) (86) International application number: PCT/US1987/000418 (87) International publication number: WO 1987/006055 (08.10.1987 Gazette 1987/22)

(84) Designated Contracting States: DE FR GB NL (30) Priority: 25.03.1986 US 19860843960 (71) Applicant: VARIAN ASSOCIATES, INC. Palo Alto, CA 94303 (US)	(72) Inventor: ANDERSON, Weston, A. Palo Alto, CA 94306 (US) (74) Representative: Cline, Roger Ledlie, et al  EDWARD EVANS & CO. Chancery House 53-64 Chancery Lane London WC2A 1SD London WC2A 1SD (GB)