bragg diffracting security markers

摘要

A method of marking articles illuminated with a water mark comprises steps on which an ordered regular array of particles is deposited on the article in a configuration which marks the article, where radiation with detected wavelength is diffracted on the said array. An article with a water mark made using the said method is also proposed. The method of making an article which shows an image comprises steps on which an ordered regular array of particles is deposited in an image configuration, the said particle array is covered by a matrix composition and the coating of the particle array is fixed such that the image is visible when radiation is diffracted on the said array.