Patent US4389230A successfully refreshed from Google Patents.
US4389230A
Expired / Lapsed
US
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Process for improving the transmission characteristics of optical fibers drawn from preforms made by the MCVD technique
Assignee: Telecom Italia SpA
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Filing: 1981-06-15
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Granted: 1983-06-21
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Expires: 2001-06-15
Abstract
Abstract In order to improve the transmission characteristics of optical fibers drawn from the preforms manufactured by vapor deposition of silica on an inner wall surface of a supporting tube of glass, the tube is subjected to a two-stage heat treatment with deuterium whereby OH - groups at least on the inner tube surface are isotopically replaced by OD - groups. This pretreatment can be carried out in the same apparatus which is subsequently used for producing the preform.
Inventors
- 👤 Eros Modone
- 👤 Giacomo Roba
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 07:59
CPC Classifications
C; C03; C03C; C03C13/00; C03C13/04; C03C13/045; C03C13/047; C03B; C03B37/00; C03B37/01; C03B37/012; C03B37/014; C03B37/018; C03B37/01853; C03B2201/00; C03B2201/06; C03B2201/20; C03B2201/22; Y; Y10; Y10S; Y10S65/00; Y10S65/90
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
136 words
A process for improving the transmission characteristics of optical fibers drawn from preforms which are produced by vapor deposition of silica on an inner wall surface of a supporting tube of silica glass, comprising the step of subjecting at least said inner wall surface of the supporting tube to a pretreatment with deuterium at elevated temperatures and for a period sufficient to isotopically replace a significant number of hydrogen atoms in the tube material close to said inner wall surface with deuterium atoms, said inner wall surface being maintained in contact with gaseous deuterium at a relatively low elevated temperature for inducing deuterium adsorption by the tube wall in a first treatment stage followed by a sharp temperature increase in a second treatment stage for promoting the substitution of hydrogen by deuterium in the tube material.
Claim 2
Dependent Claim
136 words
A process for improving the transmission characteristics of optical fibers drawn from preforms which are produced by vapor deposition of silica on an inner wall surface of a supporting tube of silica glass, comprising the step of subjecting at least said inner wall surface of the supporting tube to a pretreatment with deuterium at elevated temperatures and for a period sufficient to isotopically replace a significant number of hydrogen atoms in the tube material close to said inner wall surface with deuterium atoms, said inner wall surface being maintained in contact with gaseous deuterium at a relatively low elevated temperature for inducing deuterium adsorption by the tube wall in a first treatment stage followed by a sharp temperature increase in a second treatment stage for promoting the substitution of hydrogen by deuterium in the tube material.
Claim 3
Dependent Claim
49 words
A process as defined in claim 1 wherein the temperature is maintained in a range of substantially 100° to 200° for a period of several hours in said first treatment stage and is then raised to at least 500° C. for approximately one hour in said second treatment stage.
Claim 4
Dependent Claim
31 words
A process as defined in claim 1 or 2 wherein the entire tube is immersed in a deuterium atmosphere at elevated pressure in both said first and said second treatment stage.
Claim 5
Dependent Claim
30 words
A process as defined in claim 1 or 2 wherein the tube is traversed by a flow of pressurized and preheated deuterium gas in said first and second treatment stages.
Claim 6
Dependent Claim
23 words
A process as defined in claim 4 wherein the tube is subjected in said second treatment stage to additional localized heating from without.
References Cited (Backward Citations)
US3791714A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-06-20 | 1986-12-20 | 1987-06-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-06-20 | 1990-12-20 | 1991-06-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-06-20 | 1994-12-20 | 1995-06-21 | $7700.00 | Window Closed / Lapsed |