Optically effective surface relief microstructures and method of making them

• Main Author: Stalder, Martin
• Format: Patent
• Language: English
• Published: 16.07.2019
• Subjects: BOOK COVERS; BOOKBINDING; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDEDFOR; FILES; LOOSE LEAVES; MOVABLE-STRIP WRITING OR READING APPARATUS; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PERFORMING OPERATIONS; PHYSICS; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITYFEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOTOTHERWISE PROVIDED FOR; PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCESIN A PLASTIC STATE; SPECIAL PRINTED MATTER; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

The present invention relates to an element comprising a surface area with a specific, optically effective surface relief microstructure (12). The surface relief microstructure has a surface modulation of top regions (13) and bottom regions (14), wherein in a first lateral direction of the surface area there is in average at least one transition from a top to a bottom region or vice versa within every 20 micrometer, and in a second lateral direction of the mask, which is perpendicular to the first direction, there is in average at least one transition from a first to a second zone or vice versa within every 200 micrometer. In the microstructure, (i) in the first direction the lateral arrangement of the transitions is non-periodic, and (ii) the top regions substantially lie in the same top relief plateau (15) and the bottom regions substantially lie in the same bottom relief plateau (16).