Abstract: An optical device (10) for providing a synthetic integral image includes a polymer foil stack (111). The polymer foil stack (111) includes at least one polymer foil (11). A first interface (17) of the polymer foil stack (111) includes optically distinguishable image data bearer structures (116). The first interface (17) has a general shape defined by a first array (115) of curved interface portions (117), on which the image data bearer structures (116) are superimposed. Preferably, the optical device (10) includes a second interface (12) of the polymer foil stack (111), which has a second array (13) of microlenses (14). The second interface (12) is provided at a distance from the first interface (17), which distance is close to a focal length of the microlenses (14). The second array (13) is in registry with the first array (115).

Abstract: Methods and devices for angle determination, and retroreflecting foils are presented. A retroreflecting foil (1) is arranged at a surface, an angle of which is going to be determined. The retroreflecting foil has a lens surface with a plurality of spherical microlenses (4) and a reflecting surface with a plurality of spherical mirrors (5) of a second main radius of curvature. The lens surface of the retroreflecting foil is illuminated, and transitions between darkness and light in radiation reflected from the retroreflecting foil, either upon changing a relative angle between the retroreflecting foil and the illuminating light or spatial transitions over the surface of the retroreflecting foil, are observed. An angle measure associated with the transitions is determined. The spherical mirrors present preferably at least one inner point (22) of a spherical mirror surface at which reflection according to the second main radius of curvature is prohibited.