Abstract: An optical information carrier is presented. The information carrier comprises at least one active layer for recording/reading data in/from as a result of one- or multi-photon interaction; and at least one reference layer structure associated with said at least one active layer. The reference layer structure comprises at least one dielectric material and is different from that of the active layer in its optical properties with respect to one- or multi-photon interaction. Detection of light returned from the reference layer structure allows to control a process of focusing an optical beam onto an addressed recording plane in the active layer during at least one of the recording and reading processes.

Abstract: Cooperativity between groups within a polymeric photochromic medium provides the basis for enhanced writing effect. The cooperatively may be among photochromic groups being present in a high concentration.

Abstract: An optical information carrier and method and apparatus for securing the carrier are presented. The optical information carrier comprises a recording medium for recording data therein in the form of a first pattern of spaced-apart recorded regions configured to provide a first optical response to incident light, and comprises a pattern of spaced-apart regions configured to respond to incident light by a second optical response pattern. Distribution of the spaced-apart regions forming the second optical response pattern is indicative of an individual and identifiable carrier specific signature.

Abstract: Disclosed is a process for forming a conductor pattern on a face of a substrate, which is typically sorbing and porous, such as paper or cloth. The method comprises forming on the surface an exposed pattern of colloid particles, corresponding to the conductor pattern to be formed. The colloid particles suitable for use according to the invention are those that are capable of catalyzing electroless deposition of copper, silver, gold, and the like. After the exposed pattern of colloid particles is formed, precipitation of a metal substance on said face is caused, to form said conductor pattern.

Abstract: The present invention is directed to a 3-dimensional optical memory comprising as an active medium a compound capable of interconverting from one isomeric form to another by interaction of light. Said compound is bound to a polymer for achieving a uniform memory unit.