A security device comprises a substrate (1) having an array of microlenses (3) on one side and one or more corresponding arrays of microimages (4) on the other side. The microimages (4) are located at a distance from the microlenses (3) substantially equal to the focal length of the microlenses. The...http://www.google.com/patents/US7830627?utm_source=gb-gplus-sharePatent US7830627 - Optically variable devices
