JPS6413105A - Optical fiber and its production - Google Patents

Abstract

PURPOSE:To improve the adhesion between an inside layer resin and outside layer resin and to obtain an optical fiber having excellent reliability and transmission characteristic by forming an outside layer covering while only the surface part of an inside layer covering is not cured yet and curing the two layers by photoirradiation. CONSTITUTION:The optical fiber 3 is passed through an inside layer coating die 5 right after drawing and is coated with a liquid photosetting resin 4 on the outside circumference; thereafter the resin layer is cured by a 1st curing device 6 to first form the covering of the inside layer. Gaseous N2 from an N2 cylinder 1 and gaseous O2 from an O2 cylinder 9 are mixed in a gas mixing part 8 and while the gaseous atmosphere mixture is purged to the 1st curing device 6, the resin is cured at the time of curing the inside layer. The fiber is then inserted into an outside layer coating die 12 and is coated with a liquid setting resin 11 which is an outside layer material; in succession, the outside layer and the inside layer are cured by the 2nd curing device. The covering tightly adhered with the inside layer and the outside layer is thereby prepd., by which the transmission characteristics, move particularly the temp. characteristics are improved. The reliable optical fiber is thus obtd.