DIFFRACTIVE INDICIA FOR A SURFACE

摘要

Diffractive indicia for a surface (1) comprising a plurality of small separate diffractive elements (2) and means for adhering the diffractive elements to the surface. Each diffractive element has a diffractive surface relief structure and is not separately resolvable to the human eye. The appearance of the diffractive indicia, when applied to the surface, changes when the viewing angle and/or angle of ilumination relative to the surface changes. In preferred arrangements, the diffractive indicia are incorporated in an ink or a transfer medium. A palette of diffractive indicia with different characteristic colours and other optical properties may be provided.