Security reader for automatic detection of tampering and alteration

Abstract

A document ( ) is covered by a laminate ( ) comprising a layer of microspheres ( ) over an adhesive layer ( ) covering a source image ( ) such as a photograph, printed matter, or a bar code arranged on a substrate ( ). Light impinging on the document ( ) is split by the optical properties of the microspheres ( ) and underlying specular reflectors. The remaining light passes through the microspheres ( ), through the adhesive layer ( ) and strikes the substrate ( ) or source image ( ) on the document ( ), and is reflected ( ) and scattered ( ). Alternatively, the laminate ( ) can comprise a plain or clear layer of polyester without microspheres over the adhesive layer ( ). Light impinging on the laminate ( ) passes through the polyester and laminate ( ) to strike the substrate ( ) or source image ( ) where it is reflected and scattered. A first light source ( ) directs light to the document ( ). A second light source ( ) directs light towards a beam splitting mirror ( ) which reflects the light to the document ( ). The light turning properties of the mirror ( ) produce a light source which appears to an image receiver ( ) as being returned from the surface of the document ( ) at an angle of less than 1°. The image receiver ( ) passes a signal via line ( ) to a personal computer ( ) which processes the received information. Such processing is to establish whether the document ( ) includes a retroreflective laminate, a plain polyester laminate, or neither. Additionally, further processing can establish whether the document ( ) has been tampered with, altered, or forged.