| 摘要 |
A fibre optic transducer, which may take the form of a current sensor, and which comprises a first light path which is defined by a light transmitting element (19) and a second light path which is defined by a coil (10) of optical fibre (11). The coil-forming optical fibre (11) has a length which is significantly greater than that of the light transmitting element (19). A modulated light source (14) is provided for directing light simultaneously into both the first and the second light paths. Also, the transducer includes detector/processing circuitry (15 to 17 and 20 to 24) for detecting for light exiting from the light paths during successive time periods that include first and second time intervals t1 and t2. The detector/processing circuitry includes means for referencing the level of light that exits from the coil (10) with respect to that which exits from the light transmitting element (19) and, to this end, use is made of the difference in transmission time of light through the first and second light path having the significantly different lengths.
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