US 6,631,628 B2Granted

Method of purifying natural or synthetic silica, and application thereof to depositing purified natural or synthetic silica on an optical fiber preform

AssigneeAlcatel

InventorsAlain Drouart, Benoît Gouez, Yves Lumineau, Pierre Ripoche, Jean-Forent Campion

Life of this patent

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Abstract

Natural or synthetic silica is deposited on a preform set into rotation in front of a plasma torch which moves back and forth substantially parallel to a longitudinal direction of the preform, a first feed duct feeds the plasma with grains of natural or synthetic silica while a second feed duct feeds the plasma with a fluorine or chlorine compound, preferably a fluorine compound, mixed with a carrier gas. Any sodium or lithium contained in the grains of natural or synthetic silica react with the fluorine or chlorine of the fluorine or chlorine compound, thereby making it possible to improve the optical quality of fibers drawn from a preform built up with natural or synthetic silica, and to do so at reduced cost.

Claims3

Dependent claims

A method of purifying natural or synthetic silica in which a plasma is fed by a first feed duct with grains of natural or synthetic silica,

wherein a second feed duct feeds the plasma with a fluorine or chlorine compound mixed with a carrier gas,
the feed conditions of the two ducts are adjusted to cause alkali or alkaline-earth elements contained in the natural or synthetic silica grains to react with the fluorine or the chlorine of the fluorine or chlorine compound, causing fluorides or chlorides to be given off in gaseous form,
wherein the second feed duct is positioned entirely external to a supply source for the plasma, wherein the grains of natural or synthetic silica and the fluorine or chlorine compound are both supplied externally and directly to the plasma at an end of the supply source.

Dependencies are inferred from the claim text.

Facts

Application: 10/247,616Filed 20 Sep 2002 · continuation
Priority: FR 97 035196 Mar 1997
Published: US 2003/0019245 A130 Jan 2003
Granted: 14 Oct 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

C01B 33/12
Silicon oxides; Hydrates thereof: silica; Hydrates thereof, e.g. lepidoic silicic acid
C03B 19/01
Other methods of shaping glass: by progressive fusion or sintering of powdered glass onto a shaping substrate, i.e. accretion , e.g. plasma…
C03B 37/01291
Starting from pulverulent glass: by progressive melting, e.g. melting glass powder during delivery to and adhering the so-formed melt to a target…
C03C 1/022
Pretreated ingredients: purification of silica sand or other minerals

Family

Application09/035,146Parent of this continuation · filed 5 Mar 1998
US 2003/0019245 A1Pre-grant publication · published 30 Jan 2003
US 6,477,864 B2Parent of this continuation
US 2001/0001366 A1Published application
US 6,631,628 B2This patent

From the US filing history. Foreign family members aren’t listed.