Patent ID: 8820122

Claim:
A method for preparing a titania-doped quartz glass, comprising: feeding a silicon-providing reactant gas and a titanium-providing reactant gas through a burner tip along with a combustible gas in the form of hydrogen gas at a linear velocity of up to 100 m/sec and a combustion-supporting gas; subjecting the reactant gases to oxidation or flame hydrolysis to form synthetic silica-titania fine particles under an oxyhydrogen flame; depositing the silica-titania fine particles on a rotating target; concurrently with the depositing, melting and vitrifying the deposited particles to grow an ingot of titania-doped quartz glass; and retracting the target at such a rate that the distance between the burner tip and a growth front of the ingot is at least 250 mm; wherein the ingot has a growth axis, the burner includes a central tube for feeding the reactant gases having a nozzle axis, and the burner is oriented relative to the target such that the angle included between the growth axis and the nozzle axis is 126 degrees to 140 degrees.