Patent ID: 9540523
Date: 2017-01-10
CPC Classifications: B41M,C09D,G01N,G07D

Claim:
1. In combination with a security ink containing a first plurality of quantum dots, an optical apparatus for analyzing said security ink, comprising: a time-varying light source which excites said security ink, thereby causing said security ink to emit an emission spectrum having first and second distinct regions which are characterized by first and second distinct lifetimes; at least one photodetector; a first optical element which allows only said first region of said emission spectrum from an optical signal to pass through it; a second optical element which allows only said second region of said emission spectrum from an optical signal to pass through it; and an electronics module which determines the photoluminescence lifetime of said security ink over said first and second regions by monitoring at least one time or frequency response of said at least one photodetector.