FORM DEPICTING, OPTICAL INTERFERENCE AUTHENTICATING DEVICE

摘要

TITLE A FORM DEPICTING, OPTICAL INTERFERENCE AUTHENTICATING DEVICE INVENTORS Jerzy A. Dobrowolski Fang C. Ho Allan J. Waldorf A hard to simulate, readily distinguishable from counterfeits, optical interference authenticating device comprises a substrate, and at least one optical interference, form depicting coating on the substrate and partially covering the substrate to delineate a known, distinct and readily distinguishable form thereon. The said at least one optical interference coating comprises at least one optical interference layer having known spectral reflectance and spectral transmittance characteristics when viewed at at least one particular angle so that the form is visible in particular colouration at the or each said particular angle of incidence of light thereon by reflected or transmitted light At least one other optical interference coating may be provided on the substrate and may completely cover one side of it and the substrate may be transparent, semi-transparent or opaque, depending how the spectral characteristics are to be observed. A marginal edge portion of the form depicting coating may taper in thickness to provide a multi-coloured auriole around the form. When a plurality of form depicting coatings are provided they may partially overlie one another to provide a more complex pattern.