Method of inspecting ultraviolet curable resin for optical fiber and method of manufacturing optical fiber

A method of manufacturing an optical fiber which is performed in such a manner that a bare optical fiber is coated with an ultraviolet curable resin for an optical fiber which is recognized as an accepted product which is an ultraviolet curable resin used for manufacturing optical fiber, and then the ultraviolet curable resin for an optical fiber is cured in a method of inspecting an ultraviolet curable resin for an optical fiber having viscosity of 1.2 Pa·s to 6.2 Pa·s at a temperature of 25±5° C., the method comprising:

• placing the ultraviolet curable resin, which is an inspecting target, for an optical fiber inside a sealed apparatus, the ultraviolet curable resin for the optical fiber having viscosity of 1.2 Pa·s to 6.2 Pa·s at the temperature of 25±5° C.;
• determining, prior to decompressing an inside of the sealed apparatus, a liquid level of the ultraviolent curable resin in a testing container;
• measuring, while the inside of the sealed apparatus is decompressed, a highest liquid level of the ultraviolent curable resin in the testing container;
• determining a liquid level rise based on the determined liquid level and the measured highest liquid level;
• determining a ratio of volume expansion of the ultraviolet curable resin based on the determined liquid level rise;
• decompressing the inside of the sealed apparatus having the ultraviolet curable resin to a predetermined pressure, the inside of the sealed apparatus is left at the predetermined pressure for a predetermined time and the ultraviolet curable resin is left standing inside of the sealed apparatus;
• and
• accepting, the inspecting target as an accepted product, when the ratio of volume expansion of the ultraviolet curable resin is equal to or less than a predetermined threshold,
• wherein, when the ultraviolet curable resin is recognized as the accepted product, the ultraviolet curable resin is used for manufacturing optical fiber.