A plurality of optical transmission sources provide data communication from a transmitting module to a common detector cooperative with a receiving module, the modules being subject to relative rotation about a shared axis. The detector can be located on the shared axis, each of the sources directing a beam onto the detector regardless of relative module orientation, and/or the light can be diffused, so that it is detected regardless of source and detector placement and relative module orientations. Transmissions can be distinguished according to synchronized timing, differing optical frequencies, differing baud rates, and/or differing circular polarizations. The detector can split the light into a plurality of beams which pass through different optical filters and are thereby distinguished. Cut-off circuits can prevent failed sources from transmitting. A diffused second light source and a second plurality of detectors can provide reverse communication from the receiving module to the transmitting module.