Method of manufacturing optical fiber and apparatus for manufacturing optical fiber

An apparatus for manufacturing an optical fiber with a hole from a preform having a through hole, comprising:

• a drawing furnace configured to place the preform;
• an application device configured to apply a pressure by introducing a gas into the through hole;
• an image capturing device configured to capture an image of the optical fiber;
• a measuring unit configured to measure a hole diameter of the optical fiber based on the image captured by the image capturing device;
• and
• a controller configured to control a pressure of the gas introduced into the through hole by the application device, based on a measurement result of the measuring unit,
• wherein the image capturing device includes a mechanism that takes continuing to focus on the position of the optical fiber as a predetermined countermeasure to make the image clear and maintains the image in a clear state, when the optical fiber deviates.