(19)

(11)

EP 0 052 621 A1

(12)

(43) Date of publication: 02.06.1982 Bulletin 1982/22 (21) Application number: 81901297.0 (22) Date of filing: 27.05.1981

(51) International Patent Classification (IPC):  G01D 1/ 14( . ) H01J 37/ 24( . ) G01N 15/ 14( . ) H01J 37/ 28( . ) (86) International application number: PCT/AU1981/000065 (87) International publication number: WO 1981/003592 (10.12.1981 Gazette 1981/29)

(84) Designated Contracting States: DE GB NL SE (30) Priority: 27.05.1980 AU 19800003748 18.07.1980 AU 19800004607 (71) Applicant: COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANISATION Parkville, VIC 3052 (AU)	(72) Inventor: HARROWFIELD, Ian Roy North Fitzroy, Vic, 3068 (AU)