Patent US4586943A successfully refreshed from Google Patents.
US4586943A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the production of glass preform for optical fibers
Assignee: Sumitomo Electric Industries Ltd
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Filing: 1984-10-16
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Granted: 1986-05-06
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Expires: 2004-10-16
Abstract
Abstract A method for producing a glass preform for optical fibers by heating a glass soot preform consisting of glass fine particles made mainly of silicon oxide, which method comprises the steps of: (1) heating the glass soot preform to dehydrate and to remove impurities therefrom; (2) heating the glass soot preform in a gas atmosphere containing at least fluorine or fluorine-based compound to add fluorine to the glass soot preform; and (3) heating the glass soot preform to make it transparent, from the transparent preform prepared by which method, an optical fiber having superior transmission characteristics can be prepared.
Inventors
- 👤 Michihisa Kyoto
- 👤 Naoki Yoshioka
- 👤 Gotaro Tanaka
- 👤 Minoru Watanabe
- 👤 Hiroshi Shimba
- 👤 Nobuo Inagaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 11:51
CPC Classifications
C; C03; C03B; C03B37/00; C03B37/01; C03B37/012; C03B37/014; C03B37/01446; C03B2201/00; C03B2201/06; C03B2201/08; C03B2201/12; C03B2203/00; C03B2203/10; C03B2203/22; Y; Y10; Y10S; Y10S65/00; Y10S65/15; Y10S65/16
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
136 words
A method for producing a glass preform for optical fibers by heating a glass soot preform consisting of fine glass particles made substantially of silicon dioxide, wherein the formation of hydrogen fluoride by fluorine or fluorine-based treating compounds during heating is suppressed, which method comprises the steps of: (1) heating the glass soot preform to from 800° to 1,200° C., until it is dehydrated and any volatile impurities are removed; (2) then heating the glass soot preform at a temperature which is at most 1400° C. in a gas atmosphere containing at least fluorine or fluorine-based compound in the absence of hydrogen containing compounds to add fluorine to the glass soot preform; and (3) then after all the fluorine has been added, heating the glass soot preform to sinter said preform into a transparent glass preform.
Claim 2
Independent Claim
136 words
A method for producing a glass preform for optical fibers by heating a glass soot preform consisting of fine glass particles made substantially of silicon dioxide, wherein the formation of hydrogen fluoride by fluorine or fluorine-based treating compounds during heating is suppressed, which method comprises the steps of: (1) heating the glass soot preform to from 800° to 1,200° C., until it is dehydrated and any volatile impurities are removed; (2) then heating the glass soot preform at a temperature which is at most 1400° C. in a gas atmosphere containing at least fluorine or fluorine-based compound in the absence of hydrogen containing compounds to add fluorine to the glass soot preform; and (3) then after all the fluorine has been added, heating the glass soot preform to sinter said preform into a transparent glass preform.
Claim 3
Dependent Claim
21 words
A method as claimed in claim 1, wherein the temperature in the first heating step is from 800° to 1200° C.
Claim 4
Dependent Claim
21 words
A method as claimed in claim 1, wherein the temperature in the second heating step is from 1100° to 1400° C.
Claim 5
Dependent Claim
21 words
A method as claimed in claim 1, wherein the temperature in the third heating step is not lower than 1600° C.
Claim 6
Dependent Claim
22 words
A method as claimed in claim 1, wherein the glass soot preform is in the form of a tube or a rod.
Claim 7
Dependent Claim
20 words
A method as claimed in claim 1, wherein the third heating step is carried out in a helium gas atmosphere.
Claim 8
Dependent Claim
38 words
A method as claimed in claim 1, wherein the fluorine-based compound to be used in the second heating step is selected from the group consisting of CF 4 , SF 6 , SiF 4 and COF 2 .
Claim 9
Dependent Claim
32 words
A method as claimed in claim 1, wherein the glass soot preform comprises a core and a cladding and a bulk density of the core is larger than that of the cladding.
Claim 10
Dependent Claim
21 words
A method as claimed in claim 8, wherein the temperature in the first heating step is from 800° to 1200° C.
Claim 11
Dependent Claim
21 words
A method as claimed in claim 8, wherein the temperature in the second heating step is from 1100° to 1400° C.
Claim 12
Dependent Claim
21 words
A method as claimed in claim 8, wherein the temperature in the third heating step is not lower than 1600° C.
Claim 13
Dependent Claim
22 words
A method as claimed in claim 8, wherein the glass soot preform is in the form of a tube or a rod.
Claim 14
Dependent Claim
20 words
A method as claimed in claim 8, wherein the third heating step is carried out in a helium gas atmosphere.
Claim 15
Dependent Claim
38 words
A method as claimed in claim 8, wherein the fluorine-based compound to be used in the second heating step is selected from the group consisting of CF 4 , SF 6 , SiF 4 and COF 2 .
Claim 16
Dependent Claim
33 words
A method as in claim 1, wherein the temperature in the second heating step is from 1100° to 1400° C., and the temperature in the third heating step is not lower than 1600°.
References Cited (Backward Citations)
FR2428618A1
Cited
JPS5567533A
Cited
JPS55167149A
Cited
JPS5650136A
Cited
JPS56160333A
Cited
JPS57135735A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1989-05-05 | 1989-11-04 | 1990-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-05 | 1993-11-04 | 1994-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-05 | 1997-11-04 | 1998-05-06 | $7700.00 | Window Closed / Lapsed |