| 摘要 |
A clip-on device for detecting whether or not an optical fibre is carrying a light signal subjects a first portion of an optical fibre to microbending and detects any light escaping from the fibre as a result. The device comprises an anvil having an undulating surface and a pulsed pressure pad, driven by a motor for urging an optical fibre against the undulating surface of the anvil so that a portion of the fibre is subjected to microbending of a gradually increasing extent. A second portion of the fibre is subjected to macrobending by a light guide, which macrobending is insufficient, by itself, to cause a substantial amount of light to escape from the fibre, but serves to concentrate the light caused to leak from the fibre by microbending of the first portion of the fibre. A control unit, operatively coupled to the photodetectors and associated with the light guides and to the pressure pad gives an output indication on receipt of a signal from the photodetector that escaping light has been detected and, on receipt of such signal, stops the motor so that the pressure pad is stopped from further increasing the extent of microbending of the portion of the fibre. |
