Method of manufacturing a glass of optical quality

Glass is produced by depositing presintering composition on a preform moving in front of the plasma torch moves back and forth substantially parallel to the longitudinal direction of the preform, the first supply duct presintered in plasma grains of sintered composition was supplied, when the fluorine compounds second supply duct is mixed with a carrier gas into a plasma or chlorine compounds, advantageously provide a fluorine compound, in which the pre-sintered composition of has a BET surface area of 30~90m Granulocyte four metal oxide high-purity silicon dioxide which has been pyrogenically produced having a low metal content than the 0.2 [mu] g / g produced by reacting silicon chloride or metalloid oxide having.