Security labelling

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An optically detectable security marker for emitting light at a pre-selected wavelength comprises a rare earth dopant and a carrier incorporating the dopant. The interaction of the carrier and the dopant provide a fluorescent fingerprint different from the rare earth dopant. Independent claims are included for the following : (a) a system for validating an item having an optically detectable security feature emitting light at one of pre-selected wavelength comprising a device for illuminating the security feature with at least one wavelength for producing emissions from the rare earth dopant; a device for detecting emission from the security feature at a pre-selected wavelength; a device for comparing the detected emission with a security profile for the item; a device for the electronic selection of the photodiode signals based on the fluorescent lifetime of the detected signal corresponding to the emitted radiation from the marker; and a device for indicating a successful validation in the event of the emission matching the security profile; and (b) validating the item involving illuminating the security feature; detecting emission from the feature; comparing the detected emission; detecting and comparing the electronic signals from the photodiode based on the fluorescent lifetime; and indicating the successful validation.