DETECTION OF COUNTERFEIT ARTICLES

摘要

This invention relates to a means of invisibly marking articles for identification and authentication purposes, especially in the retail trade. Articles, or their packaging, are labelled with a mark which is only discernible as such with the aid of suitable infrared imaging equipment. A preferred embodiment exploits the sensitivity of a standard silicon charge coupled device television camera to provide a cheap readily available system which can be small enough to be used covertly. An optical filter is used to prevent visible light from entering the camera whilst allowing infrared radiation to pass and a tungsten lamp with a similar second optical filter is used to provide a covert source of infrared radiation.