| 摘要 |
Retroreflective material is used to create security features in secure documents. Retroreflective material in the document or sheets used for document creation is laser engraved to create optically variable images, identification quality grayscale images, different directional images viewable at corresponding angles of incidence, multidimensional images, and floating images. High refractive index glass beads are selectively applied to areas of a document surface using a variety of techniques. The beads may be applied in the form of a pre-determined or personalized pattern. |
