公开(公告)号：US20210370703A1

公开(公告)日：2021-12-02

申请号：US17282959

申请日：2019-10-04

Applicant: SICPA HOLDING SA

Inventor： Andrea CALLEGARI ,  Pierre DEGOTT ,  Todor DINOEV ,  Philipp EGGER

IPC: B42D25/324 ,  B42D25/21

Abstract: An optical security element made of a refractive transparent or partially transparent optical material and comprising an optical assembly of a caustic layer having a light-redirecting surface with a relief pattern of given depth and a focal length fC and an adjacent lens element of focal length fL configured to redirect incident light received from a point-like light source through it and to form a projected image containing a caustic pattern directly on a retina of an observer. A marked object, as well as a method of visually authenticating an object, and use of optical security elements for authenticating or securing against counterfeiting are also disclosed.