| 摘要 |
<p>Paper security with luminescent authenticity mark overprinted or incorporated, which is absorbant in the visible spectrum but has a transparency window in the infrared The luminescent substance emits in that window. By the absorption in the visible spectrum, the undesirable stray emissions are suppressed making then visible the luminescent substance by excitation. To check the authenticity of the document, an emission into the infrared is used. Appropriate luminescent substances are metal rare earths into appropriate host networks, particularly in ferrite or garnet networks, which contain transition metal ions as absorbing elements. </p> |
