| 摘要 |
<p>While a middle part of a plastic optical fiber bundle in a lengthwise direction thereof is being heated, it is twisted, and it is pulled in axial directions of the bundle. A biconically tapered portion is formed at the middle part of the bundle by the twisting and the pulling. When the biconically tapered portion has been formed into a predetermined shape, the heating is stopped, and simultaneously, a gas is blown against an outer periphery of the biconically tapered portion so as to rapidly cool this tapered portion. The biconically tapered portion is solidified to the predetermined shape by the rapid cooling.</p> |
