Patent ID: 8402788

Claim:
A method for manufacturing an optical fiber base material comprising: producing glass fine particles through a hydrolysis of a glass material gas in a flame created with an oxidizing gas and a combustible gas that are ejected from a burner comprising: a central gas discharge tube having a port that ejects a gas containing an oxidizing gas; a plurality of first oxidizing gas discharge tubes having a plurality of ports that eject a gas containing an oxidizing gas, the plurality of ports of the plurality of first oxidizing gas discharge tubes being arranged in a concentric circle with the port of the central gas discharge tube so as to externally surround the port of the central gas discharge tube; a combustible gas discharge tube having a port that ejects a combustible gas, the port of the combustible gas discharge tube being concentrically arranged with the port of the central gas discharge tube so as to externally surround the port of the central gas discharge tube, the combustible gas discharge tube having the plurality of first oxidizing gas discharge tubes arranged therein; and a second oxidizing gas discharge tube having a port that ejects an oxidizing gas, the port of the second oxidizing gas discharge tube being concentrically arranged with the port of the central gas discharge tube so as to externally surround the port of the combustible gas discharge tube, the method further comprising depositing the glass fine particles on a starting member to form the optical fiber base material, wherein the step of producing glass fine particles comprises controlling O 1 , O 2 , O 3 , and H so as to satisfy H/(O 1 +O 2 +O 3 )>2 and O 1 <O 2 <O 3 where O 1 denotes a gas flow rate at the port of the central gas discharge tube, O 2 denotes a gas flow rate at each of the plurality of ports of the plurality of first oxidizing gas discharge tubes, O 3 denotes a gas flow rate at the port of the second oxidizing gas discharge tube, and H denotes a gas flow rate at the port of the combustible gas discharge tube.