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US 5,330,548 AGranted
Method for producing glass preform for optical fiber
AssigneeSumitomo Electric Industries, Ltd.
InventorsToshio Danzuka, Masumi Ito, Ichiro Tsuchiya
Life of this patent
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Abstract
A transparent glass preform for an optical fiber is produced by heating a glass soot preform to remove gas from the soot preform at a temperature at which the soot preform is not vitrified under reduced pressure, and then heating the preform at a temperature at which the preform is vitrified under reduced pressure, whereby the transparent glass preform containing no or little bubbles and having a uniform outer diameter is produced.
Claims6
A method for producing a glass preform for an optical fiver, comprising the steps of:
- heating a glass soot preform to remove gas from said soot preform at a temperature of from 900.degree. to 1200.degree. C. at which said soot preform is not vitrified under reduced pressure, continuing heating until the pressure is reduced to 10 Pa or lower, and then
- heating the preform from the above-heating step at a temperature of 1500.degree. to 1600.degree. C. under pressure of 10 Pa or lower for 1 to 60 minutes at which the preform is vitrified under reduced pressure.
Dependencies are inferred from the claim text.