Embedded optical signatures in documents

摘要

A method of embedding an optical signature in a document and document produced therefrom. The optical signature uses an invisible optical pattern or covering that can reflect light in non-visible wavelengths, such as light in infrared, or fluoresces when exposed to a particular wavelength of light, such as ultra-violet light. The invisible optical pattern can be a covering over another optical pattern, or a base pattern upon which a second optical pattern is embedded.