| 摘要 |
PURPOSE:To decrease light transmission losses and to improve bendability by forming a fluorinated methacrylate copolymer as a sheath material and a vinylidene fluoride copolymer as a protective material and specifying the relation between the refractive indices of both. CONSTITUTION:A polymer essentially consisting of polymethyl methacrylate is formed as a core material, the fluorinated methacrylate copolymer having the refractive index n2 as the sheath material and the copolymer essentially consisting of the vinylidene fluoride having the refractive index n3 as the protective material. The refractive indices of the sheath material and the protective material satisfy the relation n2>=n3. Namely, this optical fiber has the soft protective layer on the outer layer of the sheath material layer and, therefore, the fiber surface does not crack in spite of the repeated bending treatment of the optical fiber. In addition, the refractive index of the sheath material is higher than the refractive index of the protective material and, therefore, light is totally reflected at the boundary between the sheath material and the protective material even if the sheath layer cracks. The generation of the large transmission loss of the light is thus obviated and the degradation in the light transmission performance by bending of the optical fiber is prevented. |
