Authenticity identifying structure for an article

An identifying structure for determining the authenticity of an article, comprising:

• an identification region provided on said article including an identification layer having a specific light reflective property, and a polarization plane rotating layer consisting of optically anisotropic material which rotates a plane of polarization of incident light to said identification region when said light is reflected by said identification region substantially by 90.degree.;
• light emitting means for projecting incident light upon said light reflecting region, said incident light comprising linearly polarized light having a certain wave length and a plane of polarization extending in a first direction;
• light receiving means for receiving exit light therefrom;
• a filter provided in association with said light receiving means, said filter allowing transmission of light having a plane of polarization extending in a second direction which is substantially perpendicular to said first direction;
• and
• identification means for detecting the authenticity of said article by evaluating said exit light received by said light receiving means;
• wherein the identification region consists of a light reflecting region comprising a multiplicity of parallel V- or U-grooves extending in parallel with each other, a hologram, or a diffraction grating having a specific diffractive property or a specific light reflective directivity;
• and
• wherein said identification layer also serves as said polarization plane rotating layer.

An identifying structure for determining the authenticity of an article, comprising:

• an identification region provided on said article including an identification layer having a specific light reflective property, and a polarization plane rotating layer consisting of optically anisotropic material which rotates a plane of polarization of incident light to said identification region when said light is reflected by said identification region substantially by 90.degree.;
• light emitting means for projecting incident light upon said light reflecting region, said incident light comprising linearly polarized light having a certain wave length and a plane of polarization extending in a first direction;
• light receiving means for receiving exit light therefrom;
• a filter provided in association with said light receiving means, said filter allowing transmission of light having a plane of polarization extending in a second direction which is substantially perpendicular to said first direction;
• and
• identification means for detecting the authenticity of said article by evaluating said exit light received by said light receiving means;
• wherein the identification region consists of a light reflecting region comprising a multiplicity of parallel V- or U-grooves extending in parallel with each other, a hologram, or a diffraction grating having a specific diffractive property or a specific light reflective directivity;
• and
• wherein said polarization plane rotating layer consists of a combination of said identification layer and a protective layer covering said identification layer.

An identifying structure for determining the authenticity of an article, comprising:

• an identification region provided on said article including an identification layer having a specific light reflective property, and a polarization plane rotating layer consisting of optically anisotropic material which rotates a plane of polarization of incident light to said identification region when said light is reflected by said identification region substantially by 90.degree.;
• light emitting means for projecting incident light upon said light reflecting region, said incident light comprising linearly polarized light having a certain wave length and a plane of polarization extending in a first direction;
• light receiving means for receiving exit light therefrom;
• a filter adjacent said light receiving means, said filter allowing transmission of light having a plane of polarization extending in a second direction which is substantially perpendicular to said first direction;
• and
• identification means for detecting the authenticity of said article by evaluating said exit light received by said light receiving means.