Security, identificaiton and verification systems

摘要

A method of operating a security system includes making a plurality of security tags, each of which includes a plurality of particles randomly distributed in a light-transmitting matrix, providing a reader which includes means for causing light of one or more wavelengths to impinge on a security tag and means for interpreting the light reflected and/or refracted and/or diffracted by the particles in the matrix, and presenting said tags to said reader.