| 摘要 |
Light pulses from laser diode 15 are transmitted by optical flbre 23 to coupler 25 which divides each pulse between further optical fibres 41a to 41d. Different delays are introduced in the fibres 41a to 41d to allow the coupler 31 to pass a train of pulses from fribres 57a to 57c and 41d along a fibre 59 to detector 17. Plate 29 is displaceable by flap 19 whose position is to be monitored and has openings 53a to 53e which control passage of light from 41a, b and c to 57a, b and c respectively in accordance with a digital code. …<??>In an alternative system the light can be reflected from different areas of the moving plate. A single coupler can be used in of 25 and 31 for both input and output functions. |
