Optically Variable Inks (OVI): versatility in formulation and usage
Pierre Degott · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2000
Optically Variable Inks (OVI) are printing inks containing high precision, multi-layer interference filters as their constituent pigment. They display a strong and unique color change form a normal to an angled viewing position. During the last 10 years OVI has gained wide acceptance as an overt protection for numerous value documents including banknotes and ID cards. Meanwhile, continuous improvement has taken place over the last two years in a variety of areas.