Patent ID: 8413908
Filing Date: 2013-04-09
Classification: G07D

Abstract:
1. An optical security mark is applied to at least part of an object, comprising at least one structure comprised by at least one metamaterial made up of a plurality of meta-atoms forming a structure, and having transverse dimensions in a plane on which meta-atoms are located, defined by the formula wherein: b b wherein the metamaterial is selected from metamaterials generating magnetic responses with a relative magnetic permeability (μ said magnetic responses produce a spectral signature when at least part of the metamaterial is subjected to said incident radiation (I) of the aforementioned wavelength or at wavelengths belonging to the same range, such that said spectral signature corresponds to at least one specific code assigned to said metamaterial, said specific code being: a value of the relative magnetic permeability at a wavelength (λ) of an incident radiation (I) according to formula wherein μ r is the relative magnetic permeability and (λ) is the wavelength of the incident radiation, or the value of the wavelength (λ) at which the metamaterial has a particular relative magnetic permeability (μ wherein λ and μ combinations of at least one specific permeability code and at least one specific wavelength code (λ), and in that said first transverse dimension and said second transverse dimension are each at least equal to the wavelength (λ) of the incident radiation.