"But then the disc's rotation speed has to be super-constant and the read:write head movement super-precise so that the positioning, depth and timing of head laser firing can match the nanocrystal sizing and layering."
Why spin the disc? Have a flat square that the head can move across, or better, have the head mounted so the read/write point is scanned by adjusting the optics, rather then move the disc or the head. Or am I missing something?