PURPOSE: To prevent the heat generation and the damage of an optical fiber, and to smoothly perform welding work by providing a fiber sheath having a space part on the outer circumferential face of the optical fiber, injecting a cool water into this space part, discharging the water and cooling the end face of the optical fiber.
CONSTITUTION: An optical fiber 14 is attached to an fiber sheath having a space part 13 on the outer circumferential face, and the fiber sheath 15 is provided with a suction tube 19, a gas tube 20 and a suction pipe 16a. A cooling water is injected into the space 13 part, and the warmed water is discharged from a discharging tube 18. Therefore, the heat generation and the damage of the optical fiber 14 are prevented, and the dew condensation generated at the end face of the optical fiber due to the cool water is also prevented by the gas suction pipe 16b.
ISHIDE TAKASHI
HASHIMOTO YOSHIO
FURUYA SHIGERU
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