Patent ID: 7462840

Claim:
A reader for a secure tag, the reader comprising a first excitation source that stimulates at least one transition; and a second excitation source that stimulates more transitions than the first excitation source; and a detector for detecting luminescence from the secure tag in response to excitation from the first excitation source and in response to excitation from the second excitation source to ensure that luminescence is detected at a pre-determined wavelength in response to the second excitation source but not the first excitation source; and a processor for processing the detected luminescence to determine if an acceptance criterion is fulfilled, wherein the acceptance criterion comprises a first set of luminescence values in response to excitation from the first excitation source, where the first set of luminescence values includes no luminescence being detected at the pre-determined wavelength; and a second set of luminescence values in response to excitation from the second excitation source, where the second set of luminescence values includes luminescence being detected at the pre-determined wavelength.