OPTICAL SAFETY ELEMENT AND SYSTEM FOR VISUALISING HIDDEN INFORMATION

摘要

The invention relates to an optical safety element and to a system for visualising hidden information which is associated with said optical element. The inventive safety optical element is provided with a substrate layer in which a relief structure defined by relief parameters such as the shape, depth, a spatial frequency and an azimuth angle and which is used for forming an optically perceptible effect in a surface area extended between axes X and Y. One or several relief parameters defining the structure thereof are modified in the area surface (27) according to a parameter variation function. The surface area (27) is divided into one or several areas pattern areas (29, 30) and a background area (28). One or several relief parameters defining the structure thereof are modified in the pattern areas (29, 30) according to the parameter variation function of the background area (28). Said invention also relates to a verification element provided with a verification raster which is defined by a periodic transmission function whose period correspond to the parameter variation function period.