Patent ID: 7389939

Claim:
A security feature, comprising: a first covert layer comprising a first covert material that is not visible to a human eye except under a first condition in which the first covert material is stimulated by a source other than visible light, the first covert layer further comprising a material constructed and arranged to produce, upon an attempted intrusion into any part of the security feature, a first effect that is visible at least under the first condition; an optically variable layer comprising an optically variable material and having first and second sides, the first side being disposed adjacent the first covert layer, the optically varying layer being constructed and arranged to cover at least a portion of the first covert layer; and a second covert layer disposed adjacent to the second side of the optically variable layer, the second covert layer being constructed and arranged to cover at least a portion of the optically variable layer, the second covert layer comprising a second covert material that is visible to the human eye only at a second condition.