| 摘要 |
PURPOSE:To obtain a preform for a long-sized image guide having little change in the outside diameter in the longitudinal direction by providing a specified structure to a preform forming capsule in which a bundle of optical transmission fibers to be integrated by sticking is put. CONSTITUTION:Bundled many optical transmission fibers are arranged so that both ends are positioned opposite to each other and the fibers are integrated by sticking to form an image guide. At this time, the bundled optical transmission fibers 1 are arranged in a capsule 9 having branch parts 9a, 9b extended in the axial directions at both the upper and lower ends. The capsule 9 is then evacuated and moved in a heating furnace 3 while supporting through the branch parts 9a, 9b to integrate the fibers 1 by sticking. |
