Optical-Effect-Producing Medium, Use Thereof and Object Having an Optically Responsive Feature Produced Using Said Optical-Effect-Producing Medium

摘要

There is described an optical-effect-producing medium comprising a carrier medium (1) containing or comprising pigment particles (10) having at least one optically responsive pigment or dye (100) that responds to incident electromagnetic radiation of at least a selected excitation wavelength or wavelength band (λ_EX) by producing an optical response in the visible or near-visible spectrum. A refractive index (n₁) of the carrier medium (1) and a refractive index (n₂; n₃) of the pigment particles (10) are selected to maximise the amount of incident electromagnetic radiation reaching the said at least one optically responsive pigment or dye (100). Also described is the use of such optical-effect-producing medium to produce an optically responsive feature, especially for security, authentication and/or identification purposes, as well as objects comprising such an optically responsive feature.