Apparatus for drawing an optical fiber and method for controlling feed speed of an optical fiber preform

An apparatus for drawing an optical fiber and a method for controlling the feed speed of an optical fiber preform whereby the drawing speed of an optical fiber is stabilized to keep the size of the outer diameter uniform. The capstan speed is determined based on the outer diameter of the optical fiber. When the capstan speed is out of a target speed range, the preform feed speed is controlled to bring the capstan speed into the target range. A control unit includes a calculation unit for receiving a drawing speed signal output from the capstan and calculating a feed speed of the perform. The control unit regulates the outer diameter of the optical fiber by regulating the speed of the capstan according to a signal received from the outer diameter measurement unit indicating a change in the outer diameter of the optical fiber.