Abstract: An optically readable information disc having a supporting plate which on at least one side has a layer of synthetic resin in which an optically readable structure has been provided which is covered with a layer of a metal alloy which is selected from the group consisting of a Ag-Cu alloy with more than 40 at.% Ag, a Cu-Cr alloy with more than 8 at.% Cr, an Al-Cr alloy with more than 75 at.% Al, an Al-Cu alloy with more than 40 at.% Al, an Al-B alloy with more than 70 at.% Al, an Al-Mn alloy with at least 75 at.% Al and an Al-lanthanide alloy with 0.1 to 3 at.% of the lanthanide.

Abstract: A method of fabricating an optical fiber by means of the double crucible method. A double crucible is used of which at least the inner crucible has a double-walled construction. The double wall accommodates a metal wire coil. During the fabrication of the optical fiber the core glass is heated by means of a high-frequency electric field and the crucible wall is cooled with a cooling liquid.BACKGROUND OF THE INVENTIONThe invention relates to a method of continuously fabricating optical fibers from a core glass and at least one cladding glass. The method uses an apparatus comprising two or more concentric crucibles (the "double crucible" method). The invention further relates to stepped index and graded index fibers obtained by this method and to an apparatus comprising at least two crucibles for use in this method.The "double crucible" method is a known technique for the continuous production of optical fibers of the graded index type as well as of the stepped index (monomode and multimode) type.