I am going to have a hard time not making one of these. I surmise the dot is always moving in a tiny circle around a central point. The instantaneous brightnes

I am going to have a hard time not making one of these. I surmise the dot is always moving in a tiny circle around a central point. The instantaneous brightness combined with the phase of the dot gives it a local map of reflectivity. This is combined with synthetic inertia and sometimes external forces (a gravity like preference in some demos) to produce the movement. The circle rate is quite high. It looks like at least 4 times the frame rate of the youtube video, maybe much more. I suppose that means some sort of coil arrangement for mirror aiming.