| 摘要 |
PURPOSE:To inexpensively obtain an optical fiber having an excellent radiation resistant characteristic and mechanical strength by subjecting a bare optical fiber obtd. by spinning a preform to a coating, then to a heating treatment in an H2 atmosphere. CONSTITUTION:The bare optical fiber 4 obtd. by inserting the preform 2 into a spinning furnace 1 provided with a resistance heating element 1a and spinning the preform is passed through a primary coater 5, by which a primary coating material (e.g.; epoxy acrylate) is coated thereon. The fiber is then passed through a heating treatment furnace 6 and is subjected to a drying and solidifying treatment, by which the optical fiber strand 9 is obtd. The strand 9 is introduced into a treatment column 8 and while the strand is passed through partition chambers 8b, 8c, and body 8a, the inside of the body 8a is kept under the H2 atmosphere (2-3atm) by supplying H2 thereto form a gas supply pipe 8e and the strand is heated to 150-250 deg.C by a heating element 8d. The strand is passed through the column at a speed of about >=10sec heating treatment time. The strand 9 passed through the column is taken up on a drum 10.
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