Patent ID: 9321670
Filing Date: 2016-04-26
CPC Classification: C03B,Y02P

Claim Text:
1. A method of manufacturing an optical fiber using an optical fiber preform, the method comprising: starting fiber-drawing after placing the distal end of the conical portion of the optical fiber preform in the central position and withdrawing a bare optical fiber which is heated and melted from the distal end of the conical portion; at the same time as the fiber drawing is started, lowering the optical fiber preform at a lowering speed of between 5 mm/min and 20 mm/min and accelerating a speed of the fiber-drawing at a rate of acceleration of between 20 m/min once a weld portion where the quartz tube is welded to the dummy tube has reached a range relative to the central position of between +10% and −10% of a length of the heater, suspending the lowering until the tapered shape in a vicinity of the weld portion is deformed; continuing the fiber drawing while the speed is accelerated at the same acceleration rate even while the lowering of the optical fiber preform is suspended; after the fiber drawing is continued until an outer diameter of the bare optical fiber reaches 10 to 20% thicker with respect to a target outer diameter, temporarily lifting up the optical fiber preform; when the outer diameter of the bare optical fiber reaches the target outer diameter by adjusting the outer diameter of the bare optical fiber so as to be narrower, resuming the lowering of the optical fiber preform at a lowering speed of between 0.2 mm/min and 5 mm/min; and accelerating the fiber drawing speed at a rate of acceleration of between 50 m/min