Hand held wireless reading viewer for bar codes printed with fluorescing inks that are invisible to the human eye. The reading viewer comprises a portable housing with a window transparent to the excitation and emission wavelengths, an LED or laser diode illuminator module having optical filter and diffuser,...http://www.google.de/patents/US7516899?utm_source=gb-gplus-sharePatent US7516899 - Hand held wireless reading viewer of invisible bar codes
