Method for producing a preform for drawing optical fibers
AssigneeAEG-Telefunken Kabelwerke AG, Rheydt
InventorsBertram Glessner, Paul Pitsch, Peter Heinen, Hartmut Peglow
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Abstract
A process is disclosed for making a preform from which optical fibers may be drawn, comprising forming a tubular glass body having a hollow center and concentric layers, at least one layer being a doped layer, and each layer having different indices of refraction. A partial vacuum is formed within the interior of the tubular glass body, at least part of the glass body is softened by heating, and the softened portions of the tubular glass body are collapsed to form a preform. The pressure of the partial vacuum is selected to effectively eliminate a dip in the index of refraction of any glass fiber drawn from the preform.
Claims21
An improved process for making a preform from which optical fibers may be drawn, said preform characterized by having essentially no reduction in index of refraction in the center of an optical fiber drawn from said preform, comprising:
- forming a tubular glass body having a hollow center and at least two concentric layers, at least one interior layer being doped, each layer having an index of refraction different from each adjacent layer;
- precollapsing said tubular glass body by heating;
- applying a partial vacuum to said hollow center of said tubular glass body;
- softening at least part of said tubular glass body by heating;
- and
- finally collapsing the softened portions of said tubular glass body under said partial vacuum to form a preform, said partial vacuum selected to effectively eliminate a dip in index of refraction in the center of any glass fiber produced from said preform.
Dependencies are inferred from the claim text.