Method of making a large MCVD single mode fiber preform by varying internal pressure to control preform straightness
US6105396A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 14, 1998 |
| Grant date | Aug 22, 2000 |
| Priority date | — |
| Expiry date | Jul 14, 2018 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC03B2203/24
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A large optical preform 303 is made by a modified chemical vapor deposition (MCVD) process by depositing successive layers of core and cladding materials onto the inside surface of a rotating glass tube 33 having a hydroxyl ion (OH.sup.-) level that is less than 0.5 parts per million (ppm) by weight. The tube is then collapsed inwardly to form a core rod 301 in which the deposited core material 31 has a diameter that is greater than about 5 millimeters and the deposited cladding material 32 has an outside diameter that is less than about 15 millimeters. A machine-vision system 140, 150, 160 monitors and controls the diameter of the glass tube by regulating the pressure within the tube. Moreover, the machine-vision system monitors and controls the straightness of the tube by varying its rotational speed according to angular position. After the core rod 301 is formed, it is plasma etched to remove contaminants, and then overclad with two glass jackets 34, 35 having a hydroxyl ion (OH.sup.-) level that is less than 1.0 ppm by weight to create a large preform 303 from which about 400 kilometers of singlemode optical fiber can be drawn per meter of length.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.