Optics: measuring and testing – Document pattern analysis or verification
Patent
1993-04-05
1995-02-28
Rosenberger, Richard A.
Optics: measuring and testing
Document pattern analysis or verification
235454, G06K 710
Patent
active
053942345
ABSTRACT:
In a preferred embodiment, a method of of of determining if a compound diffraction grating has been forged, the compound diffraction grating including a plurality of diffraction grating elements of different types, the compound diffraction grating being read by serially detecting light diffracted by the diffraction grating elements, including: determining the amplitude of diffracted light signals as the compound diffraction grating is being read; and determining that the compound diffraction grating is forged if the amplitude is below a selected threshold level. In another aspect of the invention, there is provided a method determining if such a diffraction grating has been forged, the method including: measuring the number of transitions between diffraction grating elements across the strip; and comparing the number with a pre-recorded number of the transitions and determining that the diffraction grating strip has been forged if the numbers are not the same. In a further aspect of the invention there is provided a method of determining if a compound diffraction grating has been forged, the method including: illuminating the compound diffraction grating with a beam of light substantially orthogonal to the compound diffraction grating; and determining that the compound diffraction grating has been forged when the beam of light is reflected substantially orthogonally from the compound grating.
REFERENCES:
patent: 4023010 (1977-05-01), Horst et al.
patent: 4211918 (1980-07-01), Nyfeler et al.
patent: 4501439 (1985-02-01), Antes
patent: 4544266 (1985-10-01), Antes
patent: 4641017 (1987-02-01), Lopata
patent: 5200794 (1993-04-01), Nishiguma et al.
Bianco James S.
Horan David J.
Control Module Inc.
Crozier John H.
Rosenberger Richard A.
LandOfFree
Method and apparatus for detecting forged diffraction gratings o does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for detecting forged diffraction gratings o, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for detecting forged diffraction gratings o will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-852080