| 摘要 |
PROBLEM TO BE SOLVED: To prevent various kinds of measurements in a using line under communication and to prevent both the influence, on a communication line and the influence on the measurement, so as to safely start measuring work. SOLUTION: Measuring light from a light source 2 is emitted to an optical fiber, and a reflected light from the optical fiber is branched by a branching means 3 to be detected by a photo-receiving element 4. A photo-reception level of the element 4 is output to a processing means 8 after A/D-converted by an A/D converter 6 to conduct various kinds of measurements for the optical fiber. The processing means 8 determines the optical fiber as a using line to keep emission of measuring light in a inhibited condition before the emission of the measuring light, in the case where the photo-reception level detected by the photo-receiving element 4 is a predetermined set value or more. |
