Thomson-csf

Yves Nemaud

Marc Turpin

Michel Faure

Christiane Baylac

Arnaud De Panafieu

A process for the manufacture of a glass blank in the form of a rod from which the optical fibre is drawn, said blank being produced starting from a molten bath of glass. A first stage of the process comprises melting a mixture of starting materials having a higher impurity content (&lt;10.sup.-4) in the form of so-called transition metals then the final blank (&lt;10.sup.-7). A second stage consists in inducing separation into two solid phases (a hard phase rich in silica and a soft phase poor in silica) by drawing the blank from the bath of molten glass and by subsequently subjecting it to a thermal annealing treatment. This is followed by deep etching and by peripheral etching to eliminate the soft phase and its impurities to different extents as a function of depth, which creates a radial refractive index gradient and an optical cladding.

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Paris, France

Yves Nemaud