Method of collapsing a tube for an optical fiber preform
US6718800B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 20, 2000 |
| Grant date | Apr 13, 2004 |
| Priority date | — |
| Expiry date | Feb 9, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P40/57
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
The present invention provides a method of preparing preforms for optical fibers. The invention allows one to remove or significantly reduce undesirable refractive index variations in the central portion of the optical fibers. The method of preparing the preform having a central duct includes the steps of a first collapsing step, an etching step and a second collapsing step. The first collapsing step reduces the size of the central duct without closing the central duct by heating the preform at a first preform collapsing temperature. A portion of the last deposited layer of the core glass layers is etched by flowing an etchant gas through the central duct at a lower temperature than the preform collapsing temperature. The preform is finally collapsed at a second collapsing temperature to close the central duct of the preform and form a solid rod.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.