Abstract: The invention concerns a pre-engraved substrate for a memory disc recordable by magnetic, magneto-optical or phase transition constraint, its manufacturing method and the resulting disc. Said pre-engraved substrate comprises a support (1) having at its surface a surface film (2) in a reflecting material and enabling to obtain a surface with optical polish and at least a recordable film (4), the surface film (2) and the film (4) comprising a succession of microgrooves and/or pits (7) representing a pre-formatting signal, the walls (8) of said pits and/or microgrooves (7) being formed in such of films (2) and (4) of the material constituting said film. The invention is useful for making magnetic, magneto-optical and phase transition optical discs, used particularly in the field of computers.

Abstract: Master disks for providing dies in particular for pressing optical disks, methods of manufacturing same, pressing dies obtained from such master disks and optical disks obtained from the latter and such pressing dies, the master disks consisting of a support carrying at its surface a succession of microcups representative of the information to be duplicated and consisting of a hard, conducting material reflecting in the near infrared range and selected from a zirconium, hafnium or titanium nitride or carbonitride, a hard ceramic reflecting in the near infrared range and conducting at the surface only and a hard glass reflecting in the near infrared range and conducting at the surface only.

Abstract: Master disks for providing dies in particular for pressing optical disks, methods of manufacturing same, pressing dies obtained from such master disks and optical disks obtained from the latter and such pressing dies, the master disks consisting of a support carrying at its surface a succession of microcups representative of the information to be duplicated and consisting of a hard, conducting material reflecting in the near infrared range and selected from a zirconium, hafnium or titanium nitride or carbonitride, a hard ceramic reflecting in the near infrared range and conducting at the surface only and a hard glass reflecting in the near infrared range and conducting at the surface only.

Abstract: A method for providing compact discs with an antipiracy marking and a mold for pressing compact discs for making compact discs carrying an antipiracy marking as well as compact discs comprising an antipiracy marking pattern, the compact disc consisting of a substrate including on one of its sides the information to be read by the compact disc player and on the opposite side an antipiracy marking pattern.

Abstract: The invention concerns a preformatted substrate, a preformatted substrate comprising information to be duplicated, as well as their processes of manufacture and a process of manufacture of a master disk and/or an optical disk. The preformatted substrates are constituted of a support coated with a layer of resin sensitive to at least one stress comprising on its surface a first succession of micropits or first groove representative of the preformatting signal, the depth of these micropits or groove being smaller than the thickness of the layer of photosensitive resin. These substrates may be used in the field of information archiving and in the field of manufacture of optical disks.

Abstract: An optical disk die is manufacture from a laminated disk which includes a substrate, an overlying heat sensitive layer, a reflective layer, and a final output protective layer. A laser beam forms micro-pits in the heat sensitive layer. These micro-pits become exposed after removal of the protective and reflective layers. A thin metallic coating is deposited over the surface of the pitted heat sensitive layer wherein the contours of the micro-pits are followed. A thicker second metallic layer is deposited over the first metallic layer and has an interface with the first metallic layer which duplicates a pattern of the micro-pits. Finally, the deposited second layer is separated from the remainder of the laminated disk thereby forming a die having the micro-pit pattern therein.

Abstract: A method for the manufacture of an optically readable disc, notably for providing and fixing the recording of a coded information in a sensitive resin layer applied on a transparent substrate made of an inorganic material, such as notably glass, the resin layer being preferably coated outside by a thin protective layer.According to the invention, this method is characterized in that it consists in recording in a manner known per se the signal corresponding to the coded information by localized activation of the sensitive layer through the substrate, then to remove the protective layer, to perform the engraving of the substrate through the activated zones of the sensitive layer playing the role of an engraving mask, to remove the remaining of this sensitive layer, to coat the engraved substrate with a thin reflecting metallic layer and finally to deposit on the metallic layer a final protective external layer. The invention relates also to the disc obtained by the method.

Abstract: The optimiser includes P cells for the computation and memorization of a content, the P contents simulating the deformation of a backward wave front which explores a plane representative of a concrete situation submitted to constraints.The set of elementary optimum actions which define the optimum path between an initial state and a final state are found by iteration.