| 摘要 |
PURPOSE: To surely realize the hermetic performance of a structure for hermetic sealing of an optical fiber by shrinking and forming a metallic cylinder further formed on the circumference of a buffer layer formed on the circumference of the sheath of the optical fiber in a central axial direction. CONSTITUTION: The optical fiber 2 is passed into the hole of the buffer layer 3 and the buffer layer 3 is moved up to the part where the hermetic sealing with the optical fiber 2 is desired to be executed in a first production stage. Next, the optical fiber 2 and the buffer layer 3 are inserted into the metallic cylinder 1. The optical fiber 2, the buffer layer 3 and the metallic cylinder 1 are concentrically arranged. Next, a metal mold 6 is pushed from a bore D side in the longitudinal direction from the one end of the metallic cylinder 1 in the state of fixing its position in a second production stage. The metallic cylinder 1 is then shrunk and formed in the central axial direction, by which the outside diameter is made into D-ΔD. Elastic stress is generated in the buffer layer 3 by the shrinkage of the metallic cylinder 1, by which self- restraining forces P and Q are respectively generated between the sheath of the optical fiber 2 and the buffer layer 3 and between the buffer layer 3 and the metallic cylinder 1. |
