(19)

(11)

EP 0 452 430 A1

(12)

(43) Date of publication: 23.10.1991 Bulletin 1991/43 (21) Application number: 90913856.0 (22) Date of filing: 13.09.1990

(51) International Patent Classification (IPC):  H01S 3/ 067( . ) (86) International application number: PCT/GB1990/001418 (87) International publication number: WO 1991/004594 (04.04.1991 Gazette 1991/08)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB IT LI LU NL SE (30) Priority: 15.09.1989 GB 19890021006 (71) Applicant: THE UNIVERSITY OF SOUTHAMPTON Southampton, Hampshire SO9 5NH (GB)	(72) Inventors: MORKEL, Paul Roos Southampton, Hants SO2 3PH (GB) PAYNE, David Neil Southampton, Hants SO3 5QG (GB) (74) Representative: Harland, Linda Jane, et al  c/o Reddie & Grose 16 Theobalds Road London WC1X 8PL London WC1X 8PL (GB)