公开(公告)号：EP0681711A4

公开(公告)日：1995-07-26

申请号：EP94907325

申请日：1994-01-25

申请人： PILKINGTON BARNES HIND INC

发明人： FREEMAN MICHAEL H

IPC分类号： B23K26/06 ,  G02B5/18 ,  G02C7/04 ,  G02C7/06 ,  B23K26/00 ,  G02B27/42

CPC分类号： G02B5/1895 ,  B23K26/066 ,  G02B5/1876 ,  G02C7/041 ,  G02C7/043 ,  G02C7/044 ,  G02C2202/20

摘要： A multifocal contact lens has diffractive power arising from a series of concentric zones each providing an asymmetric retardation of light across the zone width to direct light predominantly into a required order and sign of diffraction. At least some of the concentric zones are shaped so that the step height varies so that it is different in one region (A) of the lens from that in another region (B), whereby the intensity of light associated with an image observed by diffraction at one order in that region (A) of the lens is greater than the light intensity associated with the same image when observed at the same order through another region (B) of the lens.