Patent ID: 8998265
Filing Date: 2015-04-07
Classification: B42D,B44F,G02B,Y10T

Abstract:
1. A paired optically variable security element, comprising: a first optically variable interference device having a first dielectric of a lower refractive index (n a second optically variable interference device having a second dielectric of a higher refractive index (n wherein a range spanned up by said third and said fourth wavelengths of said second device is within a range spanned up by said first and said second wavelengths of said first device, and the first and the second optically variable interference devices have a same-interference design at an angle of incidence of spectral matching, and wherein, based on different refractive indexes for the first and second dielectric materials, a light propagation speed inside and outside of the first optically variable interference device is different from a light propagation speed inside and outside of the second optically variable interference device.