| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem wherein a monitoring object can not be detected when a tension of an optical cable is restored and generation of an optical transmission loss is restored. SOLUTION: This detection device wherein a photodetector measures a change of the optical transmission loss at an optical loss generation part caused by application of a tensile force to the optical cable, and an abnormality on an optional position in the longitudinal direction of the optical fiber is measured has a characteristic wherein the optical loss generation part is equipped with a change maintaining device for maintaining the change of the optical transmission loss. Hereby, the change of the optical transmission loss generated at the optical loss generation part caused by application of the tension to the optical cable is maintained as it is by the change maintaining device even if the tension applied to the optical cable is removed, to thereby detect surely the monitoring object. COPYRIGHT: (C)2005,JPO&NCIPI |
