(19)

(11)

EP 0 646 251 A1

(12)

(43) Date of publication: 05.04.1995 Bulletin 1995/14 (21) Application number: 93910213.0 (22) Date of filing: 17.05.1993

(51) International Patent Classification (IPC):  G02B 6/ 28( . ) (86) International application number: PCT/GB1993/001005 (87) International publication number: WO 1993/025923 (23.12.1993 Gazette 1993/30)

(84) Designated Contracting States: DE FR GB IT NL (30) Priority: 16.06.1992 GB 19920012727 (71) Applicant: THE SECRETARY OF STATE FOR DEFENCE IN HER BRITANNIC MAJESTY'S GOVERNMENT OF THE UNITED KINGDOM OF GREAT BRITAIN AND Farnborough, Hants. GU14 6TD (GB)	(72) Inventor: JENKINS, Richard, Michael DRA Malvern Worcs WR14 3PS (GB) (74) Representative: Beckham, Robert William, et al  Defence Research Agency Intellectual Property Department DRA Farnborough R69 Building Farnborough, Hants. GU14 6TD Farnborough, Hants. GU14 6TD (GB)