Patent ID: 8919153
Filing Date: 2014-12-30
Classification: C03B

Abstract:
1. A method of manufacturing a glass preform, comprising: a fixing step for preparing a starting member by inserting a starting mandrel into a tubular handle and fixing such that the tip portion of the starting mandrel protrudes from an end of the tubular handle; a deposition step for producing a glass soot body by depositing glass particles on the circumference of the starting member by subjecting the starting member and a glass synthesizing burner to relative two-way motions along the starting mandrel in a range extending from the tip portion of the starting mandrel to a part of the tubular handle; an extraction step for pulling out the starting mandrel from the tubular handle and the glass soot body; a vitrification step for producing a consolidated glass pipe by heating the glass soot body after the extraction step; and a collapsing step for making a solid glass preform by reducing a pressure inside of the consolidated glass pipe and heating the consolidated glass pipe, wherein the mean density of a glass soot body deposited on the circumference of the tubular handle is made larger than the mean density of a glass soot body deposited on the circumference of the starting mandrel, and the longitudinal variation in the mean density of a glass soot body deposited from the start of deposition to the tenth layer of glass particles within the range of ±50 mm from the end of the tubular handle is 0.01 g/cc/mm or less.