| 摘要 |
Each optical head of a free space optical data link includes a lens (21,22) at whose focus an end of an optical fibre (23,24) is arranged. The opto-electronic transducers (25, 28), for converting electronic signals to be transmitted to optical form and converting received optical signals to electronic form, are arranged at the other ends of the optical fibres so that the transducer may be arranged remotely from the optical heads, for example in the buildings on the roofs of which the optical heads are arranged. Adjustment means are provided for use in aligning the optical heads in attitude and azimuth, focusing, and adjusting the optical fibre to lie on the axis of the lens. A method is described of achieving maximum transmitted signal amplitude by modulation of an audio signal at the receiver in accordance with the received intensity and feeding back the modulated signal via 32 to the transmitter end to allow correct alignment of the transmitter. <IMAGE> |
