Abstract: The invention relates to an optical identifier (30) for generating an identification signal in response to an incident radiation beam (12), and to a corresponding method. In order to provide an optical identifier (30) which can be produced by a simplified process and which has nevertheless a sufficient or even improved stability against environmental interferences it is proposed that said identifier comprises a carrier layer (32), at least partially transparent to said radiation beam (12), having a first scattering face (34) comprising a plurality of randomly oriented partial faces for scattering at least a part of said radiation beam (12), wherein said identification signal is formed by a scattered part of said radiation beam (12). Further, a device comprising said identifier, and a reading apparatus for identifying the identifier are proposed.

Abstract: The invention relates to an optical identifier (30) for generating an identification signal in response to an incident radiation beam (12), and to a corresponding method. In order to provide an optical identifier (30) which can be produced by a simplified process and which has nevertheless a sufficient or even improved stability against environmental interferences it is proposed that said identifier comprises a carrier layer (32), at least partially transparent to said radiation beam (12), having a first scattering face (34) comprising a plurality of randomly oriented partial faces for scattering at least a part of said radiation beam (12), wherein said identification signal is formed by a scattered part of said radiation beam (12). Further, a device comprising said identifier, and a reading apparatus for identifying the identifier are proposed.

Abstract: An optical identifier (1) can be used as a Physical Unclonable Function for producing a speckle pattern, as a response, upon being challenged with a light beam, as a challenge. This property can be used for identification of the optical identifier or of an object attached thereto, for the authentication of an information carrier or for generation of transaction keys. Since the response obtained in response to given challenge is highly sensitive to the relative position of the optical identifier, light beam source and detector for the speckle pattern, this relative position has to be accurately adjusted to reliably obtain the same response to a given challenge. To this aim, an optical identifier is proposed having an alignment area (3) for splitting an incident beam into distinct beams (6, 7) which can be detected as alignment signals (10a, 10b, 10c, 10d) on a detector (8) and used for the monitoring and for the adjustment of said relative position.

Abstract: An optical information carrier comprises a data layer for carrying the information, an outer surface for receiving a light beam for reading the information, and a transparent layer for transmitting the light beam to the data layer. The transparent layer comprises a pattern of physical damages for locally deforming the light beam. The physical damages are embedded in the transparent layer at a depth between the outer surface and the data layer. In the pattern of physical damages additional information is encoded. The additional information may be used for the purpose of copy protection.