US4636236A
Expired / Lapsed
US
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Method for producing a preform for drawing optical fibers
Assignee: Alcatel Lucent SAS
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Filing: 1985-05-23
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Granted: 1987-01-13
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Expires: 2005-05-23
Abstract
Abstract A process is disclosed for making a preform from which optical fibers may be drawn, comprising forming a tubular glass body having a hollow center and concentric layers, at least one layer being a doped layer, and each layer having different indices of refraction. A partial vacuum is formed within the interior of the tubular glass body, at least part of the glass body is softened by heating, and the softened portions of the tubular glass body are collapsed to form a preform. The pressure of the partial vacuum is selected to effectively eliminate a dip in the index of refraction of any glass fiber drawn from the preform.
Inventors
- 👤 Bertram Glessner
- 👤 Paul Pitsch
- 👤 Peter Heinen
- 👤 Hartmut Peglow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 23:52
CPC Classifications
C; C03; C03B; C03B37/00; C03B37/01; C03B37/012; C03B37/014; C03B37/018; C03B37/01861; C03B37/01869
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
146 words
An improved process for making a preform from which optical fibers may be drawn, said preform characterized by having essentially no reduction in index of refraction in the center of an optical fiber drawn from said preform, comprising: forming a tubular glass body having a hollow center and at least two concentric layers, at least one interior layer being doped, each layer having an index of refraction different from each adjacent layer; precollapsing said tubular glass body by heating; applying a partial vacuum to said hollow center of said tubular glass body; softening at least part of said tubular glass body by heating; and finally collapsing the softened portions of said tubular glass body under said partial vacuum to form a preform, said partial vacuum selected to effectively eliminate a dip in index of refraction in the center of any glass fiber produced from said preform.
Claim 2
Dependent Claim
146 words
An improved process for making a preform from which optical fibers may be drawn, said preform characterized by having essentially no reduction in index of refraction in the center of an optical fiber drawn from said preform, comprising: forming a tubular glass body having a hollow center and at least two concentric layers, at least one interior layer being doped, each layer having an index of refraction different from each adjacent layer; precollapsing said tubular glass body by heating; applying a partial vacuum to said hollow center of said tubular glass body; softening at least part of said tubular glass body by heating; and finally collapsing the softened portions of said tubular glass body under said partial vacuum to form a preform, said partial vacuum selected to effectively eliminate a dip in index of refraction in the center of any glass fiber produced from said preform.
Claim 3
Dependent Claim
17 words
The process of claim 1, wherein the collapsed tubular glass body has an essentially circular cross section.
Claim 4
Dependent Claim
34 words
The process of claim 1, wherein the tubular glass body is precollapsed under atmospheric pressure to ensure its mechanical stability, thereby resulting in a preform having an essentially circular cross section after final collapsing.
Claim 5
Dependent Claim
16 words
The process of claim 1, wherein the tubular glass body is collapsed over its entire length.
Claim 6
Dependent Claim
18 words
The process of claim 1, wherein the tubular glass body is collpased over only part of its length.
Claim 7
Dependent Claim
22 words
The process of claim 1, wherein the tubular glass body is collapsed into a preform in the shape of a solid rod.
Claim 8
Dependent Claim
45 words
The process of claim 1, wherein the tubular glass body is collapsed into a tubular preform having a hollow center, wherein the diameter of the preform and the diameter of its hollow center are both less than the corresponding diameters in the tubular glass body.
Claim 9
Dependent Claim
43 words
The process of claim 1, wherein the tubular glass body is first collapsed at one end, thereby sealing that end; forming a partial vacuum within the interior of the tubular glass body; and, thereafter, sealing the opposite end of said tubular glass body.
Claim 10
Dependent Claim
20 words
The process of claim 8, wherein the tubular glass body sealed at both ends is drawn into a glass fiber.
Claim 11
Dependent Claim
33 words
The process of claim 8, wherein, after being sealed both ends, said tubular glass body is collapsed along essentially its entire length into a preform and, thereafter, is drawn into a glass fiber.
Claim 12
Dependent Claim
25 words
The process of claim 1, wherein the collapsed portions of the preform can be drawn into a fiber that has an essentially circular cross section.
Claim 13
Dependent Claim
38 words
The process of claim 1, wherein the tubular glass body is precollapsed under less than atmospheric pressure, a partial vacuum is created within its interior, and the precollapsed tubular glass body is further collapsed to form a preform.
Claim 14
Dependent Claim
40 words
The process of claim 1, wherein the tubular glass body has a deficient doped layer from which doping material has evaporated, and said deficient doped layer is removed before applying the partial vacuum to said hollow center of said body.
Claim 15
Dependent Claim
20 words
The process of claim 1, wherein the formation of a deficient doped layer within the tubular glass body is prevented.
Claim 16
Dependent Claim
17 words
The process of claim 1, conducted within an environment having a pressure of less than atmospheric pressure.
Claim 17
Dependent Claim
33 words
The process of claim 15, wherein the pressure within the interior of the tubular glass body is reduced with respect to the pressure acting on the outer wall of the tubular glass body.
Claim 18
Dependent Claim
31 words
The process of claim 1, wherein at least one concentric layer having a different index of refraction from that of the doped layer comprises an essentially pure SiO 2 glass layer.
Claim 19
Dependent Claim
13 words
The process of claim 1, wherein the doped layer is a coating layer.
Claim 20
Dependent Claim
14 words
The process of claim 18, wherein the coating layer is composed of doped silicon.
Claim 21
Dependent Claim
32 words
The process of claim 19, wherein the doped silicon comprises a doping substance selected from the group consisting of germanium dioxide, phosphorus pentoxide, and a combination of germanium dioxide and phosphorus pentoxide.
Claim 22
Dependent Claim
14 words
The process of claim 13, wherein said deficient doped layer is removed by etching.
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) | 1990-01-12 | 1990-07-14 | 1991-01-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-12 | 1994-07-14 | 1995-01-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-12 | 1998-07-14 | 1999-01-13 | $7700.00 | Window Closed / Lapsed |