| 摘要 |
PURPOSE:To simplify a photocircuit constitution, by a method wherein a semiconductor laser is used as a light-emitting element and a light-receiving element as well. CONSTITUTION:A photopulse from a semiconductor laser 1, driven from a pulse generator 10, is coupled to a light path 3 via a lens 11. When the photopulse propagates in the light path 3 and if a fault point 4 exists, the size of a back scattering light changes discontinuously. An impedance measuring device 13 measures the impedance of the semiconductor laser 1, and an oscilloscope 9 measures a time which has elapsed unitl the impedance value, which is the measurement results, changes discontinuously to find a distance to the fault point 4. |
