Patent US4693738A successfully refreshed from Google Patents.
US4693738A
Expired / Lapsed
US
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Method for producing glass preform for optical fiber
Assignee: Sumitomo Electric Industries Ltd
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Filing: 1985-09-30
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Granted: 1987-09-15
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Expires: 2005-09-30
Abstract
Abstract An optical fiber comprising a core essentially made of quartz and a cladding made of fluorine added quartz is fabricated with good productivity from a glass preform produced by a method comprising maintaining a hollow cylindrical porous glass preform in a first high temperature atmosphere comprising at least one fluorine-containing compound with jetting a cooling gas through the central hollow part of the porous glass preform to grade the amount of fluorine to be added in the radial direction of the porous glass preform and then sintering the porous glass preform in a second high temperature atmosphere kept at a temperature higher than the first high temperature atmosphere to make it transparent.
Inventors
- 👤 Masao Hoshikawa
- 👤 Michihisa Kyoto
- 👤 Koji Yano
- 👤 Gotaro Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 01:47
CPC Classifications
C; C03; C03B; C03B37/00; C03B37/10; C03B37/14; C03B37/01; C03B37/012; C03B37/014; C03B37/01446; C03B37/0146; C03B37/12; C03B2201/00; C03B2201/06; C03B2201/08; C03B2201/12; C03B2203/00; C03B2203/10; C03B2203/22; C03B2203/26; Y; Y02; Y02P; Y02P40/00; Y02P40/50; Y02P40/57; Y10; Y10S; Y10S65/00; Y10S65/15; Y10S65/16
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
163 words
A method for producing a glass preform for an optical fiber comprising the steps of: maintaining, for a sufficient contact time, a hollow cylindrical porous glass preform in a first high temperature atmosphere comprising at least one gaseous fluorine-containing compound while jetting a cooling gas through the central hollow part of the porous glass preform to grade an amount of fluorine thereby added in the radial direction of the porous glass preform, said amount of fluorine added to the porous glass preform being added in sufficient quantity and under proper operating conditions to modify the refractive index of said porous glass preform, and said cooling jet being sufficient to provide for the establishment of a gradient of partial pressure of the fluorine-containing compound which increases toward the outer periphery of the porous glass preform, and then sintering the porous glass preform in a second high temperature atmosphere kept at a temperature higher than the first high temperature atmosphere to make the preform transparent.
Claim 2
Independent Claim
163 words
A method for producing a glass preform for an optical fiber comprising the steps of: maintaining, for a sufficient contact time, a hollow cylindrical porous glass preform in a first high temperature atmosphere comprising at least one gaseous fluorine-containing compound while jetting a cooling gas through the central hollow part of the porous glass preform to grade an amount of fluorine thereby added in the radial direction of the porous glass preform, said amount of fluorine added to the porous glass preform being added in sufficient quantity and under proper operating conditions to modify the refractive index of said porous glass preform, and said cooling jet being sufficient to provide for the establishment of a gradient of partial pressure of the fluorine-containing compound which increases toward the outer periphery of the porous glass preform, and then sintering the porous glass preform in a second high temperature atmosphere kept at a temperature higher than the first high temperature atmosphere to make the preform transparent.
Claim 3
Dependent Claim
20 words
A method according to claim 1, wherein the porous preform is a fine glass particle mass produced by flame hydrolysis.
Claim 4
Dependent Claim
19 words
A method according to claim 2, wherein the fine glass particle mass is made of pure quartz glass particles.
Claim 5
Dependent Claim
12 words
A method according to claim 1, wherein the cooling gas comprises helium.
Claim 6
Dependent Claim
14 words
A method according to claim 1, wherein the first high temperature atmosphere comprises chlorine.
Claim 7
Dependent Claim
34 words
A method according to claim 1 wherein the fluorine-containing compound is at least one selected from the group consisting of SF 6 , CF 4 , C 2 F 6 and SiF 4 .
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-09-14 | 1991-03-16 | 1991-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-09-14 | 1995-03-16 | 1995-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-09-14 | 1999-03-16 | 1999-09-15 | $7700.00 | Window Closed / Lapsed |