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Abstract

Polymer-based optically-variable devices (OVDs) for security applications and methods for producing the same. The uniformity of thickness of the structure of such devices is optimized by controlling previously neglected process parameters such as the temperature distribution of the deposition nozzle, the substrate and the deposition drum, their emissivities, the micro-roughness of the substrate, and the rate of monomer re-evaporation. Re-evaporation is minimized by initiating radiation-curing within two seconds of monomer deposition. A method includes equipment reducing all sources of emissivity non-homogeneities, such as surface blemishes in the surface areas exposed to the substrate to preferentially fabricate substrates with haziness less than 5% and gloss greater than 90%. Controlling, a maximum variation of thickness of the transmissive layer of an OVD ensures that no appreciable color-shift variation is visible to the naked eye.

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First Claim