| 摘要 |
In apparatus for authenticating documents (12) such as banknotes, light reflected from, or transmitted through, a document (12), is formed by a lens system (20) to a beam (32) which is directed to a series of wavelength selective beam splitters (34) each of which transmits light of greater than a characteristic wavelength and reflects light of lesser wavelength. The characteristic wavelengths of the beam splitters (34) increase or decrease along the series. The resulting output beams (36) are sensed by photosensors (40) to produce electrical signals which are digitized. The resulting data is analyzed, for example, by comparison with corresponding data derived from a genuine document, to provide an output signal on a line (48) indicative of the authenticity of the document (12). <IMAGE> |
