Claims
- 1. A method for producing a silica glass preform containing fluorine for use in the fabrication of an optical fiber, which comprises the steps of:
- (1) forming a porous silica glass soot around a transparent glass rod core from a glass-forming raw material by vapor deposition to obtain a complex glass preform,
- (2) heating the complex glass preform in an atmosphere consisting of SiF.sub.4 under a pressure of from 2 atm. to 20 atm. for a period of time sufficient to add fluorine to the complex glass preform during the time between formation of soot preform and a subsequent vitrification of the preform, and
- (3) heating the complex glass preform formed in step (2) at a higher temperature at which the complex glass preform is vitrified to form a transparent silica glass preform.
- 2. The method according to claim 1, wherein SiF.sub.4 is continuously flowed in the heating atmosphere.
- 3. The method according to claim 2, wherein SiF.sub.4 is flown at a rate not lower than 50 ml/min.
- 4. The method according to claim 1, wherein the heating temperatures are not lower than 800.degree. C.
- 5. The method according to claim 4, wherein the temperatures are not lower than 800.degree. C. and not higher than 1,400.degree. C.
Priority Claims (1)
Number |
Date |
Country |
Kind |
60-87580 |
Apr 1985 |
JPX |
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Parent Case Info
This is a divisional application of Ser. No. 526,522 filed May 21, 1990, now U.S. Pat. No. 5,053,068, which is a continuation of Ser. No. 211,158, filed Jun. 22, 1988, now abandoned, which is a continuation of Ser. No. 855,396, filed Apr. 24, 1986, now abandoned.
US Referenced Citations (3)
Foreign Referenced Citations (3)
Number |
Date |
Country |
55-67533 |
May 1980 |
JPX |
56-50136 |
May 1981 |
JPX |
60-51635 |
Mar 1985 |
JPX |
Divisions (1)
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Number |
Date |
Country |
Parent |
526522 |
May 1990 |
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Continuations (2)
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Number |
Date |
Country |
Parent |
211158 |
Jun 1988 |
|
Parent |
855396 |
Apr 1986 |
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