Machine readable identification information in hologram bar=code - having fixed and variable code section formed by combination of two diffraction angle materials and blanked out section

摘要

The bar code pattern is produced in a hologram form that has +45 and -45 degrees diffraction elements. The pattern is formed in 2 layers and consists of a fixed and a variable code structure. A light source (1) is directed vertically onto the surface and the top layer has both +45, -45 or blanked out sections. The reflected beam is received by one of two detectors (2,3). For the variable coding bar code is formed in blanked out sections, such that the beam reflects off the lower layer. ADVANTAGE - Provides protection against falsification.