EP0195407A1
Expired / Lapsed
EP
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Method for producing glass preform for optical fiber
Assignee: Sumitomo Electric Industries Ltd
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Filing: 1986-03-18
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Granted: —
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Expires: 2006-03-18
Abstract
Abstract A method for producing a glass preform for use in fabrication of an optical fiber, which comprises steps of forming a glass soot preform (1) from a glass-forming raw material, optionally heating the soot preform (1) under reduced pressure at a temperature at which the soot preform (1) is not vitrified, heating the soot preform (1) in an atmosphere comprising at least one fluorine-containing compound under reduced pressure or a pressure not lower than atmospheric pressure if the soot preform has been heated under the reduced pressure in the previous step, or under reduced pressure if the soot preform has not been heated in the previous step, and vitrifying the fluorine-added preform for a sufficient time to vitrify it, by which a glass preform having substantially no bubble therein and containing a sufficient amount of fluorine.
Inventors
- 👤 Michihisa C/O Yokohama Works Kyoto
- 👤 Yoichi C/O Yokohama Works Ishiguro
- 👤 Akira C/O Yokohama Works Urano
- 👤 Hideo C/O Yokohama Works Kakuzen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 11:17
CPC Classifications
C; C03; C03B; C03B37/00; C03B37/01; C03B37/012; C03B37/014; C03B37/01446; C03B37/0146; C03B2201/00; C03B2201/06; C03B2201/07; C03B2201/075; C03B2201/08; C03B2201/12; Y; Y10; Y10S; Y10S65/00; Y10S65/15; Y10S65/16; Y10S65/90
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
114 words
A method for producing a glass preform for'use in fabrication of an optical fiber, which comprises steps of: forming a glass soot preform from a glass-forming raw material, optionally heating the soot preform under reduced pressure at a temperature at which the soot preform is not vitrified, heating the soot preform in an atmosphere comprising at least one fluorine-containing compound under reduced pressure or a pressure not lower than atmospheric pressure if the soot preform has been heated under the reduced pressure in the previous step, or under reduced pressure if the soot preform has not been heated in the previous step, and vitrifying the fluorine-added preform for a sufficient time to vitrify it.
Claim 2
Independent Claim
114 words
A method for producing a glass preform for'use in fabrication of an optical fiber, which comprises steps of: forming a glass soot preform from a glass-forming raw material, optionally heating the soot preform under reduced pressure at a temperature at which the soot preform is not vitrified, heating the soot preform in an atmosphere comprising at least one fluorine-containing compound under reduced pressure or a pressure not lower than atmospheric pressure if the soot preform has been heated under the reduced pressure in the previous step, or under reduced pressure if the soot preform has not been heated in the previous step, and vitrifying the fluorine-added preform for a sufficient time to vitrify it.
Claim 3
Dependent Claim
76 words
The method according to claim 1, which comprises steps of: forming a glass soot preform from a glass-forming raw material, heating the soot preform under reduced pressure at a temperature at which the soot preform is not vitrified, filling the spaces in the soot preform with at least one fluorine-containing compound, heating the soot preform in the presence or absence of the fluorine-containing compound, and vitrifying the fluorine-added preform for a sufficient time to vitrify it.
Claim 4
Dependent Claim
15 words
The method according to claim 2, wherein the fluorine-containing compound is in a gas state.
Claim 5
Dependent Claim
47 words
The method according to claim 3, wherein the fluorine-containing compound is one selected from the group consisting of SiF 4 , SF 6 , CF 4 , C 2 F 6 , C 3 F 8 , CC1 2 F 2 and COF 2 and mixtures thereof.
Claim 6
Dependent Claim
14 words
The method according to claim 4, wherein the fluorine-containing compound is SiF 4 .
Claim 7
Dependent Claim
26 words
The method according to claim 2, wherein the fluorine-containing compound is filled in the spaces of the soot preform under pressure not lower than atmospheric pressure.
Claim 8
Dependent Claim
21 words
The method according to claim 2, wherein the latter heating step of the soot preform is carried out under reduced pressure.
Claim 9
Dependent Claim
27 words
The method according to claim 2, wherein at least a part of the soot preform has a bulk density of not smaller than 0.4 g/cm 3 .
Claim 10
Dependent Claim
16 words
The method according to claim 2, wherein the vitrification step is carried out under reduced pressure.
Claim 11
Dependent Claim
19 words
The method according to claim 2, wherein the latter heating step and the vitrification step are simultaneously carried out.
Claim 12
Dependent Claim
54 words
The method according to claim 2, wherein the soot preform consisting of S10 2 glass soot particles is heated under reduced pressure at a temperature at which the soot preform is not vitrified and vitrified under reduced pressure in an atmosphere comprising SiF 4 for a sufficient time to add fluorine to the preform.
Claim 13
Dependent Claim
49 words
The method according to claim 1, which comprises steps of forming a glass soot preform from a glass-forming raw material, heating the soot preform in an atmosphere comprising at least one fluorine-containing compound under reduced pressure for a sufficient time to add fluorine thereto, and vitrifying the fluorine-added preform.
Claim 14
Dependent Claim
18 words
The method according to claim 11, wherein the heating step and the vitrification step are simultaneously carried out.
Claim 15
Dependent Claim
26 words
The method according to claim 11, the pressure or the partial pressure of the fluorine-containing compound in the heating step is from 0.01 to 0.5 atm.
Claim 16
Dependent Claim
17 words
The method according to claim 11, which further comprises dehydrating the soot preform before the heating step.
Claim 17
Dependent Claim
27 words
The method according to claim 11, wherein the soot preform consists of a core portion of a pure glass and a peripheral portion of glass soot particles.
References Cited (Backward Citations)
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