Patent ID: 7082791

Claim:
A method of manufacturing a soot preform for an optical fiber by depositing glass particles generated through a flame hydrolysis reaction of raw material gases onto a starting rod being rotated and pulled up, comprising: providing an apparatus that comprises: a reaction chamber for depositing said glass particles over the starting rod; an upper room located on top of said reaction chamber, for housing the soot preform being pulled up; at least one core deposition burner disposed in the reaction chamber; a horizontally extending slit made in an upper portion of a sidewall of the reaction chamber which is closest to said core deposition burner, at a location slightly underneath a ceiling of said reaction chamber; and a gas exit made in a wall of the reaction chamber which is opposed to the wall having said slit; disposing the starting rod in said reaction chamber; passing the gases into said reaction chamber through said slit; operating the burner to deposit said glass particles over the starting rod; and pulling up the starting rod deposited with said glass particles, wherein a velocity of the gases passing through said slit is set between 3 m/sec and 20 m/sec.