| 摘要 |
<p>PURPOSE:To identify a heat detected place with a simple arrangement by utilizing the local microbending loss of a covered optical fiber caused by the contraction of a press-winding type composed of a thremo-contracting material. CONSTITUTION:Covered optical fibers 12 are twisted together around a center tensile strength wire 11, a press-winding tape 13 composed of the thermo- contracting material is wound on the fibers 12, a metallic conduit 14 having high heat conductivity is applied as a housing, and solid particles are included in the covering layers of the covered optical fibers 12. Consequently, when the ambient temperature becomes high, the press-winding tape 13 contracts in its longitudinal direction, the optical fibers 12 including the solid particles in their covering layers are pressed and meander discontinuously, and optical transmission loss caused by microbending increases. Thus, time of day and the place where the ambient temperature rises can be accurately detected by continuously monitoring the longitudinal directional optical transmission loss distribution of the optical fibers 12 by a back scattering light measuring instrument.</p> |
