The present invention relates to a method for the replication of a patterned surface relief microstructure, comprising the steps of generation of a first layer with a patterned surface relief microstructure, generation of a master, by copying the microstructure of the first layer into a second layer, thereby involving at least one dry or wet etching step, characterized by an additional step, in which the microstructure of the master is brought into contact with a replica material, such that the microstructure of the master is reproduced in the replica. The invention further relates to the elements made as a replica according to the method. The surface relief microstructures are suitable to display images with a positive-negative and/or color image flip. The elements according to the invention are particularly useful for securing documents and articles against counterfeiting and falsification.

Disclosed are techniques and systems for manufacturing an optical disc having a stochastic (i.e., non-deterministic) anti-piracy feature in the form of a multi-spiral structure, and for verifying the feature on the optical disc to authenticate the disc for playback. The multi-spiral structure may be comprised of multiple partially interleaved, and partially overlapping, spiral data tracks formed in a designated area of the optical disc. A process of forming the multi-spiral structure may include forming, in the designated area, a first spiral data track with first track pitch and a second spiral data track with second track pitch that is different than the first track pitch. The multi-spiral structure may be analyzed to determine verification parameters for verifying the multi-spiral structure, and those verification parameters may be encrypted so that they may be subsequently decrypted and used to verify the multi-spiral structure on a disc reading device.