Method of applying a pattern, and security device for an article

Abstract

Methods of applying a pattern and security devices are disclosed. In one arrangement, a receiving member having a layered structure is provided. The layered structure comprises a layer of phase change material. The phase change material is thermally switchable between a plurality of stable states having different refractive indices relative to each other. An embossing member is stamped into the receiving member. The embossing member heats a selected portion of the layer of phase change material via contact with the receiving member during the stamping. The heating thermally switches phase change material in the selected portion and thereby applies a pattern of different refractive indices to the layer of phase change material.

Dependencies are inferred from the claim text.