Optical fiber manufacturing method and optical fiber manufacturing apparatus

An optical fiber manufacturing method comprising[H]:

• a passing process, passing a glass fiber through a fiber path before applying a resin, the glass fiber being drawn from a glass preform, the fiber path being formed through a cooling tube, and the cooling tube being housed in a casing and being cooled by a coolant;
• and
• applying the resin to the glass fiber after the passing process,
• wherein the passing process includes
• supplying a dry gas into a dry space formed between the casing and the cooling tube, the dry gas having a first dew point lower than a temperature of the cooling tube,
• measuring, by a dew point meter, a second dew point at one or both of an inlet and an outlet of the fiber path, and
• controlling a flow rate of the dry gas such that the second dew point measured by the dew point meter is lower than the temperature of the cooling tube.

An optical fiber manufacturing method comprising[H]:

• a passing process, passing a glass fiber through a fiber path before applying a resin, the glass fiber being drawn from a glass preform, the fiber path being formed through a cooling tube, and the cooling tube being housed in a casing and being cooled by a coolant;
• and
• applying the resin to the glass fiber after the passing process,
• wherein the passing process includes
• supplying a dry gas into a dry space formed between the casing and the cooling tube, the dry gas haying a first dew point lower than a temperature of the cooling tube,
• measuring, by a dew point meter, a second dew point at one or both of an inlet and an outlet of the fiber path, and
• controlling the first dew point of the dry gas supplied into the casing, such that the second dew point measured by the dew point meter is lower than the temperature of the cooling tube.