Dust, mist, and/or Rayleigh scattering means I wouldn't need to be in the beampath to "see" it, but I guess if you've solved the problem of aiming a collimated laser beam from a moving ship to another moving ship, and reliably hitting the "receiver" at the far end, you can probably do it at low enough power levels to make that very hard…
Doesn't help - the quadcopter's cameras don't _need_ to be only sensitive to the human-visible spectrum.
(having said that, Rayleigh scattering is frequency dependant, if I recall my high school physics correctly, IR will scatter lees than visible light – I doubt thst matter though, in ship-to-ship communication there'd be more than enough mist/water in the air to scatter enough IR for a suitable camera to see the beam)
