The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 01, 1990
Filed:
Jun. 13, 1985
Giacomo Roba, Genova-Cogoleto, IT;
Abstract
In producing a preform for an optical fiber by MCVD technology, involving the buildup of a core matrix of doped silica layers inside a glass tube with subsequent thermal collapse of the structure, a layer of dopant is deposited on the inner surface of the finished core matrix before the collapse. The thickness of this dopant layer, which advantageously is in a colloidal state, progressively diminishes along the tube axis in a direction away from an end of the tube at which the collapse begins. The law of thickness variation is chosen to maintain an internal gas pressure of vaporized dopant equal to the vapor pressure of the dopant in the core material at the collapsing temperature, in order to prevent the appearance of a paraxial dip in the refractive-index profile of an optical fiber subsequently drawn from the collapsed preform.