Diffractive Surfaces With Color Shifting Backgrounds

Abstract

A security article includes a light transmissive substrate having a first surface and an opposing second surface, with the first surface having an embossed region with an optical diffraction pattern or a holographic image pattern. A color shifting optical coating is formed on the substrate such as on the opposing second surface, with the optical coating providing an observable color shift as the angle of incident light or viewing angle changes. The security article can be used in a variety of applications and products to provide for enhanced security measures such as anticounterfeiting.

1 . A security article comprising: a light transmissive substrate having a first surface and an opposing second surface, said first surface having a diffraction grating pattern or a holographic image pattern formed thereon; and a color-shifting multilayer optical film structure formed on said diffraction grating pattern or said holographic image pattern formed on said first surface of said light transmissive substrate, so as to conform to the shape thereof, said color-shifting multilayer optical film structure being defined by a reflector layer formed directly on said diffraction grating pattern or said holographic image pattern formed on said first surface of said light transmissive substrate, a dielectric layer formed directly on said reflector layer, and an optical absorber layer formed directly on said dielectric layer and having a first surface thereof opposite a second surface thereof formed directly on said dielectric layer, said first surface of said reflector layer replicating said diffraction pattern or said holographic image pattern formed on said first surface of said light transmissive substrate; and wherein said color-shifting multilayer optical film structure provides color shifting with change of viewing angle or angle of incident light.  
   
   
       2 . A security article as defined in  claim 1 , wherein the first surface of the absorber layer has the diffraction pattern or holographic image pattern replicated and formed therein.  
   
   
       3 . A security article as defined in  claim 1 , wherein a layer of the color-shifting multilayer optical film structure is segmented.  
   
   
       4 . A security article as defined in  claim 2  wherein a layer of the color-shifting multilayer optical film structure is segmented.  
   
   
       5 . A security article as defined in  claim 3  wherein the reflector layer is segmented.