Manufacturing method of optical fiber

Abstract

The present invention provides a manufacturing method of optical fiber that improves the adherence between a coating and a bare optical fiber composed of silica glass during the formation of the coating on the bare optical fiber in high-speed drawing of optical fiber. In this method, the temperature of the bare optical fiber prior to being introduced into a coating material in the coating apparatus is made to be between 60 and 110° C. The bare optical fiber is cooled by blowing cooling gas onto that prior to being introduced into the coating material in the coating apparatus. Furthermore, during cooling of bare optical fiber, at least two types of cooling gases having different coefficients of thermal conductivity are mixed and blown onto the bare optical fiber. In addition, the temperature of the bare optical fiber is made to be within a prescribed range by changing the mixing ratio of the cooling gas.

Dependencies are inferred from the claim text.