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US4040807A
Expired / Lapsed
US
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Drawing dielectric optical waveguides
Assignee: Post Office
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Filing: 1975-06-30
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Granted: 1977-08-09
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Expires: 1995-06-30
Abstract
Abstract The attenuation in a dielectric optical waveguide can be reduced by the following techniques: 1. Surrounding the double crucible during the drawing operation by a non-oxidizing atmosphere. 2. Feeding glass rod into the melt at a slow rate. 3. Guiding glass rod into the melt so that movement of the glass rod transverse to the melt surface is inhibited. 4. Melting the glass in the double crucible under vacuum.
Inventors
- 👤 John Edwin Midwinter
- 👤 Clive Richard Day
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:50
CPC Classifications
C; C03; C03B; C03B5/00; C03B5/16; C03B5/225; C03B5/2252; C03B37/00; C03B37/01; C03B37/02; C03B37/022; C03B37/023; C03B37/08; C03B37/085
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
132 words
A method of manufacturing a bubble-free dielectric optical waveguide comprising: loading preformed core and cladding glasses in rod form into the inner and outer compartments respectively of a metallic double crucible, having concentric adjacent outlet orifices, cladding glass being loaded in said outer and core glass in said inner compartment melting the glasses in said crucible; completely surrounding the double crucible containing melted glasses with a nonoxidising atmosphere; drawing from said orifices core and cladding glasses to form a clad dielectric optical waveguide; and continuously replenishing said inner and outer compartments of the double crucible by feeding preformed core and cladding glass rods having a diameter between 3 and 10 millimeters into the glass melt at a rate less than 30 millimeters per minute thereby avoiding pulling gas into the glass melt.
Claim 2
Independent Claim
132 words
A method of manufacturing a bubble-free dielectric optical waveguide comprising: loading preformed core and cladding glasses in rod form into the inner and outer compartments respectively of a metallic double crucible, having concentric adjacent outlet orifices, cladding glass being loaded in said outer and core glass in said inner compartment melting the glasses in said crucible; completely surrounding the double crucible containing melted glasses with a nonoxidising atmosphere; drawing from said orifices core and cladding glasses to form a clad dielectric optical waveguide; and continuously replenishing said inner and outer compartments of the double crucible by feeding preformed core and cladding glass rods having a diameter between 3 and 10 millimeters into the glass melt at a rate less than 30 millimeters per minute thereby avoiding pulling gas into the glass melt.
Claim 3
Dependent Claim
13 words
A method as claimed in claim 1 wherein the non-oxidising atmosphere includes carbon-dioxide.
Claim 4
Dependent Claim
13 words
A method as claimed in claim 2 wherein the non-oxidising atmosphere includes carbon-monoxide.
Claim 5
Dependent Claim
20 words
A method as claimed in claim 2 wherein said non-oxidising atmosphere includes between 5% and 90% by volume of carbon-monoxide.
Claim 6
Dependent Claim
20 words
A method as claimed in claim 2 wherein said non-oxidising atmosphere includes between 5% and 20% by volume of carbon-monoxide.
Claim 7
Dependent Claim
16 words
A method as claimed in claim 2 wherein said non-oxidising atmosphere is dried prior to use.
Claim 8
Dependent Claim
19 words
A method as claimed in claim 2 wherein said non-oxidising atmosphere is heated to remove carbonyls prior to use.
Claim 9
Dependent Claim
13 words
A method as claimed in claim 1 wherein the non-oxidising atmosphere includes nitrogen.
Claim 10
Dependent Claim
14 words
A method as claimed in claim 8 wherein the non-oxidizing atmosphere includes carbon monoxide.
Claim 11
Dependent Claim
23 words
A method as claimed in claim 8 wherein said non-oxidizing atmosphere includes between 5 percent and 90 percent by volume of carbon monoxide.
Claim 12
Dependent Claim
23 words
A method as claimed in claim 8 wherein said non-oxidizing atmosphere includes between 5 percent and 20 percent by volume of carbon monoxide.
Claim 13
Dependent Claim
16 words
A method as claimed in claim 8 wherein said non-oxidizing atmosphere is dried prior to use.
Claim 14
Dependent Claim
19 words
A method as claimed in claim 8 wherein said non-oxidizing atmosphere is heated to remove carbonyls prior to use.
Claim 15
Dependent Claim
19 words
A method as claimed in claim 1 wherein said rod has a diameter of between 6 and 8 mm.
Claim 16
Dependent Claim
22 words
A method as claimed in claim 14 wherein said feed rate is greater than 15 and less than 30 mm per minute.
Claim 17
Dependent Claim
40 words
A method of loading glass into a heated double crucible as claimed in claim 15 wherein prior to feeding said glass rod into said double crucible, said glass rod is stored in a silica tube in a dry inert atmosphere.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-08 | 1981-02-07 | 1981-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-08 | 1985-02-07 | 1985-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-08 | 1989-02-07 | 1989-08-09 | $7700.00 | Window Closed / Lapsed |