Patent ID: 7175086
Filing Date: 2007-02-13
Classification: G01N,G11B

Abstract:
1. An authentication system, comprising: a first light source having a first light source spectral distribution and being capable of providing sufficient excitation to produce a photoluminescent emission from a medium comprising a luminescent tag and a color, wherein the photoluminescent emission has a photoluminescence intensity; a second light source having a visible multi-wavelength spectral distribution and being capable of providing sufficient visible multi-wavelength illumination of the medium to generate a second analog response, wherein the second analog response is different from the photoluminescent emission; and at least three optically filtered light sensing devices for detecting analog emission intensity in a spectral sensitivity range; wherein each light sensing device has a different device spectral sensitivity range which includes at least a portion of the visible multi-wavelength spectral distribution; wherein the device spectral sensitivity range of at least one of the light sensing devices includes at least a portion of a desired photoluminescent emission wavelength range; and wherein each light sensing device is configured to receive at least one of the photoluminescent emission and the second analog signal.