| 摘要 |
<p>An information carrier is produced with an optical diffraction grating pattern that is embedded into the structure and is difficult to copy. The carrier has a laminated structure (3, 4, 5). The diffraction grating structure is produced as a fine surface pattern in two of the layers (4, 5). The optical refractive index values (n3, n4, n5) of the layers are selected such the differences (n4-n3) and (n5-n3) are in the visible range and are approximately equal and greater than 0.2. The absolute difference (n4-n4) is in a second spectral range and is less than 0.1. A centre layer (4) has a data structure (7) that is optically machine read.</p> |
