| 摘要 |
<p>The invention discloses a method and a device for the authentication of a document, a valued good or a packaging, carrying a marking (M) exhibiting a viewing-angle dependent light reflection spectrum. The authentication method is based on a measurement of the intensity of light reflected by the marking at least at two different viewing angles in response to a sequential wide-angle illumination with light of different spectral characteristics, and the comparison of the measured intensity values with corresponding reference values. The authentication device (1) has at least two light sources (4) of different spectral characteristics, a wide-angle illumination optics (3), and at least two photodetectors (5) collecting light reflected by said markings at least at two different viewing angles. It may further have a programmed "learning mode" for measuring and storing a set of reflected intensity values of a reference item, and a programmed "testing mode", for measuring a corresponding set of intensity values on an item to be authenticated and comparing them with the previously stored set of reference values, hereby deriving and indicating a test result.</p> |
