I agree that alignment and interference are problems if one wants multiple beams. If you're using lasers one way I see is to split each signal beam into a grid

I agree that alignment and interference are problems if one wants multiple beams. If you're using lasers one way I see is to split each signal beam into a grid so it's many rays in a grid pattern where a few rays will hit the target sensor array. Multiple grids can then be overlaid without interference. The sensor grid at the target must be able to detect which sensor is receiving which beam and adapt over time. Overall that doesn't sound infeasible to me. But then I don't do optics, so maybe I'm ignorant of a basic limitation.