Abstract: A coin (1) with a metal surface (2, 3) has macroscopic reliefs (5) which serve for visually specifying the value of the coin and as an authenticity feature. Microscopically fine relief structures (8) with a diffraction effect are formed directly in at least one of the surfaces (2, 3). The relief structures (8) are preferably arranged in a recessed relationship and are covered with a lacquer (9). It is also advantageous if at least a part of the relief structures (8) entails an asymmetrical profile shape and/or the grating vectors in a radial orientation. The release structures (8) may also include a machine-readable coding which is recognized by inexpensive optical reading devices for installation in coin testers. The application of the microscopic relief structure (8) to a hard material surface (2, 3) can be effected by the removal of material by means of exposure of the material surface (2, 3) with a laser beam.

Abstract: The optical waveguide coupler comprises a structure (1) of a number of elongated narrow optical waveguide strips (2), which consist respectively of a front area (3), a center area (4) and a coupling area (5). The center area (4) has respective transition areas (6) and (7) to the corresponding area (3) or (5). A gap (9) in the front areas (3) provided between two adjoining strips (2) is larger than the thickness of the narrow strips (2). The front faces (8) of the front areas (3), and the front faces of the coupling areas (5) are embodied to be as smooth as possible, wherein all strips form a stack in the coupling area (5). The gaps are pits which result from etching of an Si substrate with the aid of a DRIE etching process.