Patent ID: 7891217

Claim:
A method of producing an optical fiber preform, the method comprising a step of depositing a glass film on the inner wall surface of a starting pipe by heating the starting pipe from the outer circumferential surface thereof with a plasma burner so as to oxidize a glass raw material and deposit a glass film on the inner wall surface of the pipe while introducing a gas containing the glass raw material into the pipe, the plasma burner being moved in parallel with the axis of the pipe; wherein the plasma burner includes at least two inlets of gases for forming plasma and the inner diameter thereof at the region where the plasma is formed is 80 mm or more, and the deposition step is performed in a manner such that the relationship, 150 mm/second <Q/S <600 mm/second is satisfied, wherein Q is the total flow rate of the gases introduced into the burner, and S is the sectional area at the region.