Method and apparatus for reading and verifying holograms

Abstract

A system and method for reading the information stored in holograms and other diffractive objects. The information is read by analyzing the diffraction pattern produced when a laser beam is focused onto a small spot on the object and scanned across the object.

1 - 13 . (canceled)  
   
   
       14 . A security device comprising an arrangement of light-emitting particles on a surface, said arrangement forming a pattern of varying spectral emission properties corresponding to each of the light emitting particles.  
   
   
       15 . The security device of  claim 14 , wherein said light-emitting particles are selected from the group consisting of fluorophores, quantum dots, fluorescent fibers, and nanometer-sized particles.  
   
   
       16 . The security device of  claim 14 , wherein said light-emitting particles are quantum dots composed of a plurality of layers including at least one layer of a semiconductor material.  
   
   
       17 . The security device of  claim 16 , wherein said semiconductor material is comprised of a first layer of CdSe and a second layer of ZnSe.  
   
   
       18 . The security device of  claim 14 , wherein said arrangement provides a representation of information that is at lest one of random and structured information.  
   
   
       19 - 20 . (canceled)