Patent ID: 6840063

Claim:
A method for manufacturing an optical fiber preform, comprising the steps of: depositing a clad layer and a core layer on an inner surface of a preform tube by using a first heater to form a deposited tube; shrinking one end of the deposited tube by using said first heater to seal the one end of the deposited tube; arranging the deposited tube having the sealed end and an open end vertically through a circular heater by making the sealed end the upper end; moving the circular heater to said one end of the deposited tube, and then adjusting a heating temperature of the circular heater to be not lower than a softening point of the deposited tube; and shrinking and closing the deposited tube by heating the deposited tube while moving the circular heater at a desired speed and rotating the deposited tube, wherein a flame pressure of said circular heater during the shrinking and closing step is higher than a flame pressure of said first heater during the deposition step.