Patent US4610709A successfully refreshed from Google Patents.
US4610709A
Expired / Lapsed
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Method for producing glass preform for optical fiber
Assignee: Sumitomo Electric Industries Ltd
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Filing: 1985-01-23
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Granted: 1986-09-09
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Expires: 2005-01-23
Abstract
Abstract Fluorine is selectively added to a cladding portion of a glass preform by producing a soot preform which comprises a core portion and a cladding portion under such conditions that an additive concentration or a bulk density of the outermost part of the core portion is to be larger than that of the inner part thereof and heating the soot preform in an atmosphere containing fluorine or fluorine-containing compound at least for some period to obtain a transparent glass preform.
Inventors
- 👤 Hiroshi Kawauchi
- 👤 Michihisa Kyoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:01
CPC Classifications
C; C03; C03B; C03B37/00; C03B37/10; C03B37/12; C03C; C03C13/00; C03C13/04; C03C13/045; C03B37/01; C03B37/012; C03B37/014; C03B37/01413; C03B37/0142; C03B37/01446; C03B2201/00; C03B2201/06; C03B2201/08; C03B2201/12; C03B2203/00; C03B2203/10; C03B2203/22; C03B2207/00; C03B2207/36; Y; Y10; Y10S; Y10S65/00; Y10S65/15; Y10S65/16
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
144 words
A method for producing a glass preform, comprising the steps of: producing a soot preform which comprises a core portion and a cladding portion wherein a metal oxide additive concentration or a bulk density of a radially outer part of said core portion is larger than that of said cladding portion and is larger than that of the radially inner part of said core portion to a degree such that when said soot preform is heated, said radially outer part sinters first, and heating said soot preform in an atmosphere containing fluorine or a fluorine-containing compound until a transparent glass preform is formed, the addition of the fluorine or fluorine-containing compound in the heating step being timed such that said radially outer part sinters before said cladding portion and thereby substantially prevents the penetration of fluorine into said inner part of said core portion.
Claim 2
Independent Claim
144 words
A method for producing a glass preform, comprising the steps of: producing a soot preform which comprises a core portion and a cladding portion wherein a metal oxide additive concentration or a bulk density of a radially outer part of said core portion is larger than that of said cladding portion and is larger than that of the radially inner part of said core portion to a degree such that when said soot preform is heated, said radially outer part sinters first, and heating said soot preform in an atmosphere containing fluorine or a fluorine-containing compound until a transparent glass preform is formed, the addition of the fluorine or fluorine-containing compound in the heating step being timed such that said radially outer part sinters before said cladding portion and thereby substantially prevents the penetration of fluorine into said inner part of said core portion.
Claim 3
Dependent Claim
31 words
A method according to claim 1, wherein before the heating step is the step of heating said soot preform in an atmosphere containing a chlorine-containing compound to dehydrate said soot preform.
Claim 4
Dependent Claim
26 words
A method according to claim 1, wherein the heating step includes the step of heating said soot preform at a temperature of 1,000° to 1300° C.
Claim 5
Dependent Claim
44 words
A method according to claim 1, wherein the producing step includes the step of producing said soot preform wherein both said additive concentration and said bulk density of said radially outer part of said core portion are larger than that of said cladding portion.
Claim 6
Dependent Claim
36 words
A method as in claim 1, wherein, at the time the fluorine or fluorine-containing compound is added, said radially outer part has relative density of ≧0.45, and said cladding portion has a relative density of <0.45.
References Cited (Backward Citations)
US3806224A
Cited
US4165223A
Cited
JPS54160414A
Cited
FR2428618A1
Cited
JPS5567533A
Cited
JPS58208146A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-09-08 | 1990-03-10 | 1990-09-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-09-08 | 1994-03-10 | 1994-09-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-09-08 | 1998-03-10 | 1998-09-09 | $7700.00 | Window Closed / Lapsed |