| 摘要 |
PURPOSE:The preform for optical fiber is heated in a quartz tube reciprocating in the vertical direction to inhibit contaminants from furnace materials from depositing on the preform or on the resultant optical fiber whereby the strength of the drawn optical fiber is increased. CONSTITUTION:When the preform 1 is drawn into optical fiber 1A, a vertically reciprocating quartz tube is set on the axis of the furnace which is composed of carbon heaters 2 and carbon core tube 3. Then, the preform 1 is inserted into the quartz tube 10 and the objective optical fiber is formed by drawing. According to the process of the present invention, the fine particles or impurities flying out of the carbon core tube 3 and the carbon heaters 2 precipitate on the outer surface of the quartz tube 10 and carbon heaters 2 precipitate on the outer surface of the quartz tube 10 and the contamination of the preform 1 or the optical fiber 1A can be completely avoided. Thus, the resultant fiber is made free from impurities and damages and has increased strength. Moreover, the quartz tube 10 vertically reciprocates without local heating, resulting in prolonged life. |
