Patent ID: 6994257
Filing Date: 2006-02-07
Classification: G06K

Abstract:
1. An apparatus for retrieving information, encoded as a function of surface dimension and thickness of at least one of a plurality of materials, said materials mildly absorbing radiation over a range of infrared wavelengths and substantially non-absorbing in visible wavelengths, at select wavelengths, comprising: at least one of a plurality of sources of radiation wherein said at least one of a plurality of sources of radiation emits infrared radiation over a range of frequencies; means for scanning the at least one of a plurality of sources of radiation over the medium and material disposed thereon, wherein a portion of said radiation is reflected or transmitted from the medium and material disposed thereon, said reflected or transmitted portion having a variable intensity over a scan, a variation of said intensity being a function of infrared radiation absorption or transmission characteristics of the medium and material and the thickness and surface dimensions of the material disposed on the medium; means for collecting the reflected or transmitted portion of the radiation at each of a plurality of select wavelengths, from the range of wavelengths emitted by the at least one of a plurality of sources of radiation; means for converting said collected radiation at each of the plurality of select wavelengths into a plurality of electrical signals; means for determining, from the plurality of electrical signals, the reflectance or transmittance at the plurality of select wavelengths, for each of a plurality of spaced apart locations on the medium and material disposed thereon, placement of said locations being along the scan; means for identifying, from the reflectance or transmittance at the plurality of select wavelengths at each of the plurality of spaced apart locations on the medium and material disposed thereon, the thickness and presence of the material at each of the plurality of spaced apart locations; means for deducing the surface dimensions of the material from presence of the material at each of the plurality of spaced apart locations; means for decoding the information encoded in the thickness and surface dimension of the material.