| 摘要 |
<p>A fibre optic switch (24) which includes an actuator (162, 166) reversibly movable between at least two switch positions, an actuator position detector (23) and a single optical fibre path (20) connected between the actuator and the actuator position detector. A beam splitter (18) is provided to couple light from a light source into the fibre so as to travel towards the actuator. A filter (162, 166) is selectably insertable into the path of light emanating from an end of the fibre at the actuator and a retroreflector (168) reflects the filtered light back to the fibre. The reflected light is directed by the beam splitter towards the actuator position detector.</p> |
