SECURITY READER FOR AUTOMATIC DETECTION OF TAMPERING AND ALTERATION

A document (10) is covered by a laminate (13) comprising a layer of microsph eres (16) over an adhesive layer (14) covering a source image (12) such as photograph, printed matter, or a bar code arranged on a s ubstrate (11). Light impinging on the document (10) is s plit by the optical properties of the microspheres (16) and underlying specular r eflectors. The remaining light passes through the micros pheres (16), through the adhesive layer (14) and strikes the substrate (11) or sour ce image (12) on the document (10), and is reflected (18 ) and scattered (20). Alternatively, the laminate (13) can comprise a plain or cle ar layer of polyester without microspheres over the adhe sive layer (14). Light impinging on the laminate (13) passes through the polyeste r and laminate (14) to strike the substrate (11) or sour ce image (12) where it is reflected and scattered. A first light source (24) directs light to the document (10). A second light source (26, 2 7) directs light towards a beam splitting mirror (23) which reflects the light to to th e document (10). The light turning properties of the mir ror (23) produce a light source which appears to an image receiver (40) as being retu rned from the surface of the document (10) at an angle o f less than 1.degree.. The image receiver (40) passes a signal via line (32) to a p ersonal computer (41) which processes the received infor mation. Such processing is to establish whether the document (10) includes a retroreflect ive laminate, a plain polyester laminate, or neither. Ad ditionally, further processing can establish whether the document (10) has been tampered with, altered, or forged.