Patent attributes
The present invention relates to a counterfeit-proof volume hologram multilayer structure capable of securely preventing a counterfeiter from replicating a volume hologram recorded therein. The multilayer structure comprises a transparent surface protective layer, a volume hologram layer, and an adhesive layer which are sequentially laminated and is characterized in that particles having particle diameter of 350 nm or more are dispersed in at least one of the transparent surface protective layer, the volume hologram layer, and the adhesive layer and that the refractive index ratio (nF/nB) is set to be not less than 1.05 or not greater than 0.95, wherein nF is the refractive index of the particles and nB is the refractive index of the medium in which the particles are dispersed, or characterized in that at least either the refractive index ratio (nP/nH) between the transparent surface protective layer and the volume hologram layer or the refractive index ratio (nH/nA) between the volume hologram layer and the adhesive layer is set to be not less than 1.08, wherein nP is the refractive index of the transparent surface protective layer, nH is the refractive index of the volume hologram layer, and nA is the refractive index of the adhesive layer.
