I'm really curious how the tracking works in such a system, and how "bad" the beam spread is (my impression is that from the diffraction limit alone the beam has to be spread over at least a ~10m radius after travelling 36000km).

Some info on the laser itself would also be very interesting (power? wavelength?).

Really cool project though!

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amelius 4 hours ago | parent | next [-]

> and how "bad" the beam spread is

The spread makes the tracking easier, I suppose.

	▲	TimorousBestie 3 hours ago \| parent [-]
		Perhaps a little, however. Different paths through the atmosphere will perturb the phase of the signal; depending on conditions not all of that ~10m beam width is going to decode with an acceptable bit error rate.

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mytailorisrich 2 hours ago | parent | prev [-]

Tracking and actuation is nothing new or particularly challenging, IMHO. It's the laser/optical part combined with throughput at that distance that is the main area of R&D, I think.