US Patent 11747268 Coded polymer substrates for banknote authentication

A method and system for authenticating an item includes irradiating the item, the item including a polymer substrate including a polymer material and a doping material and configured to emit a radiation spectrum having a spectral signature in response to the irradiating, the doping material capable of absorbing or scattering radiation at a specific wavelength to generate the spectral signature, detecting the spectral signature, and determining a code associated with the spectral signature.