Patent ID: 8139839

Claim:
An apparatus for checking the authenticity of bank notes in unprotected areas, comprising: a sensor assembly containing a light source which produces light of a first wavelength with which the bank notes to be checked are illuminated, whereupon illumination by the first wavelength of one or more feature substances present in and/or on the bank notes produce light of a second wavelength detected by the sensor assembly; and a control device arranged to evaluate data received from the sensor assembly about the light of the second wavelength and compare the data with reference data to determine the authenticity of the bank notes; wherein structure and operation of the sensor assembly and/or the control device permits conclusions to be drawn on the feature substance or substances contained in the bank notes without initially revealing the feature substance or substances contained in the bank notes, wherein the sensor assembly and control device is arranged to detect and evaluate at least one further property of the bank notes and is arranged to execute a check of the feature substance or substances only upon an indication of the presence of a bank note in the check of the further property and is arranged not to execute a check of the feature substance or substances upon an indication of the presence of a forged bank note in the check of the further property.