U.S. Philips Corporation

Polygram Gmbh

Du Pont Optical Company

501 Philips & Du Pont Optical Company

Horst-Christian Langowski

Gerhard F Eggers

Klaus Schmitz

A cathode-sputtering apparatus for the surface-coating of objects has a vacuum chamber which contains a helium-group gas, in which chamber a target cathode and an anode are arranged. A voltage for producing plasma discharges is applied to these electrodes and a magnetic field is applied, which intensifies the plasma discharges and concentrates them at the location of the target cathode. For measuring a critical target-consumption condition, at least one probe is provided in the target cathode, which probe is actuated when the target material is eroded up to the probe.

Cathode-sputtering apparatus comprising a device for measuring critical

A method is described for the vacuum-coating of substrates, such as glass plates, foils, plastics substrates for optical discs etc., in which the substrates are introduced into a vacuum-coating arrangement and are vacuum-coated in accordance with a PVD (physical vapour-deposition) process such as for example cathode sputtering or vapour-deposition. In order to avoid pinholes in the coating the method is carried out in three steps, namely a first PVD step, in which the substrates and any particles adhering thereto are coated; a particle-displacement step in which the coated particles are displaced from their initial positions on the substrate; and an additional, second PVD step, in which the substrates are coated a second time to cover the defects formed in the coating by adhering particles in the first coating step.

Method of removing particles from substrate surfaces

An optically readable, high storage density information carrier usually in the form of a disk, for example, a digitally recorded audio disk (CD) or a video disk (VLP) including a base, and a microstructure on the base which contains the recorded information, and consists of spiral or annular tracks or channels on one or both sides thereof. A reflective layer of a suitable metal or alloy is applied to the side of the information disk carrying the microstructure in at least that portion in which the microstructure exists. The present invention provides an improved reflective layer which, in turn, is covered by a protective layer. The improved reflective layer is a metal alloy selected from one of the following groups of alloys: (1) a Cu-Cr alloy containing from 0.3 to 1.5% chromium, (2) an Al-Mg-Si alloy containing 0.5 to 1.5% each of magnesium and silicon, and (3) an Mg-Mn-Si alloy containing 1.2 to 2% manganese and 0.05 to 0.1% silicon.

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Hanover, Germany

Horst-Christian Langowski