| 摘要 |
PURPOSE:To dispense with a drive power source and to remove the effect of electromagnetic induction, by detecting the movement of a magnetic body part by an earth current as light transmission loss due to the change in the width of the gap between the end surfaces of optical fibers. CONSTITUTION:When an earth current flows to an earth cable 20, a magnetic field is generated and a magnetic body part 13 moves so as to be attracted to the earth cable 20. When the magnetic body part 13 moves as mentioned above, the end surface 2a of one optical fiber 2 moves simultaneously. Because the other optical fiber 1 is fixed by a fixing jig 15, said optical fiber 1 does not move and the width of the gap between the end surfaces 1a, 2a of the optical fibers 1, 2 becomes large. If the width of the gap between the end surfaces of the optical fibers becomes large, an earth current can be detected by the increase in the transmission loss of light transmitted from one optical fiber to the other. |
