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:
Sep. 08, 1992
Filed:
Jan. 14, 1991
Michihisa Kyoto, Yokohama, JP;
Yoichi Ishiguro, Yokohama, JP;
Akira Urano, Yokohama, JP;
Hideo Kakuzen, Yokohama, JP;
Sumitomo Electric Industries, Ltd., Osaka, JP;
Abstract
A glass preform is produced by forming a glass soot composite body having a core portion consisting of a solid glass and a peripheral portion consisting of a porous glass mass, removing trapped gas and water from pores of the soot composite body by heating the soot composite body under a pressure lower than several ten Torr. at a temperature at which the porous glass mass is not vitrified, filling the pores in the porous glass mass of the soot composite body with a gas containing SiF.sub.4, the partial pressure of which is a function of the desired specific difference of refractive index, thus uniformly adding fluorine to the soot glass mass, and vitrifying the fluorine-added soot glass mass into a transparent glass mass to form a glass preform.