| 摘要 |
A security document, such as a banknote or a check, is provided with a perforation pattern (5) having holes (5a, 5b) with elongate cross section. When viewing the perforation pattern (5) from a direction that is non-perpendicular to the surface of the document, different holes will have different optical transmission, which can be verified by eye or electronically. Perforation patterns (5) of this type are hard to forge and easy to verify. |
