Abstract: To prevent unauthorized duplication of an information storage cards such as magnetic cards, IC cards, and optical cards, the card carries an identification region which may be identified by a simple optical sensor. The identification region may consist of holograph, diffraction grating, a multiplicity of parallel grooves and other processed surfaces having certain reflective or transmissive directivities. In particular, the identification region comprises a plurality of segments having two or more different reflective or transmissive directivities, and these segments are uniformly distributed in the identification region so that all of the segments may be accessed simultaneously by the optical sensor which comprises a light emitter and a light receiver including a plurality of parts each capable of individually detecting light reflected by or transmitted through the identification region.

Abstract: A highly simple and compact optical head for optically determining authenticity of an article by impinging a light beam upon an identification region provided on the article and having a selected reflective directivity, and receiving light reflected by the identification region. The identification region may consist of a holograph, a diffraction grating or a multiplicity of parallel grooves. The optical head comprises a light emitting element fixedly secured to a casing and a light receiving element placed coaxially in a light path of a light beam emitted from the light emitting element and having an opening for allowing the light beam to pass through the light receiving surface facing away from the light emitting element and being divided into a plurality of sectors defined around an axial center line of the light emitting element with each of the sectors being capable of individually detecting a magnitude of light impinging thereon.