DOVID

DOVID

A diffractive optically variable image device (DOVID) is a type of optical variable device; a security feature based on visual effects created by diffraction. DOVIDs are incorporated in government-issued documents of value (banknotes, passports, visas, identification credentials and driver licenses) to increase their counterfeit resistance. Brand protection is another application of DOVIDs. DOVIDs contain micro- or nanostructures in the form of diffractive gratings. Due to these structures, they exhibit optically variable effects such as dynamic chromatic, holographic, and kinematic effects, two- or three-dimensional images or color-changing effects, which ideally are easily recognized, but are difficult to reproduce. Well known examples of DOVIDs are holograms such as 2D or 3D or 2D/3D holograms based on mask illumination, dot matrix or e-beam origination technology and Kinegrams.A DOVID can also contain elements which are invisible to the unaided human eye such as microprint, kinetic microtext, or a variable laser-readable micro-image that is invisible when magnified under white light. DOVID structures can be incorporated in a foil: which is then hot stamped on a paper document (e.g., banknote, visa), incorporated within the structure of a polycarbonate or composite card (e.g., passport, driver licenses) before personalization or integrated in a laminate that is heat sealed to the surface of a card after personalization (e.g., driver licenses, identity cards).

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