Retroreflective security features in secure documents
View Patent ↗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.
1. A secure document comprising:
a core layer;
a retroreflective material applied to the core layer, the retroreflective material being on a surface of the secure document, and wherein different directional grayscale images are laser engraved in the same location on the retroreflective material at corresponding first and second angles of incidence wherein the different directional images laser engraved at the same location represent different types of information about a bearer of the secure document; and wherein the retroreflective material is selectively applied to an area, but less than the entire area of the surface and forming a pre-determined or personalized pattern; and
wherein, the laser engraving is carried out with a neodymium:yttrium aluminum garnet (Nd:YAG) laser having a wavelength output of about 1064 nm, operating at 10 watts maximum, a beam diameter of about 2.3 mm to 10 mm, and a frequency of about 50 Khz.
2. The document of claim 1 comprising a host layer shaped in the form of the pre-determined or personalized pattern, the retroreflective material comprising beads selectively embedded in the pattern.
3. The document of claim 1 comprising a host layer, the retroreflective material comprising beads selectively embedded in the host layer in a shape of the pattern.
4. The document of claim 1 wherein the pattern comprises a pattern conveying personal information of a bearer of the document.