I've seen a few projected laser image systems, most of them pretty small, but here's one that seems similar to the majority.

http://www.circuitcellar.com/flash2002...stract.htm

and you might want to see

http://en.wikipedia.org/wiki/Laser_video_projector

Manufacturers exploit this spinning mirror technology for a number of reasons, not the least of which is that it's easier to build a fixed, spinning mirror mechanism and a single moving mirror, with the system relying on electronics and timing, rather than two moving mirrors that have to rely not only on electronics and timing, but on very precise manufacturing as well.

I don't know a lot about lasers, but I do know a fair amount about positioning systems, particularly fixed-disk head actuators, many of which were designed and fabricated not far from here. I also have some knowledge of what is easy to manufacture, and what is not.

I also know a bit about the mechanical problems of linear positioners, ranging from valves on rocket engines, to carriages on flatbed plotters. I mention the latter because the original question in this thread was about feedback mechanisms. You can imagine that a 1.3x2-meter plotter, with two degrees of freedom and pretty high carriage/pen velocity (>1.5 m/sec) would require pretty good feedback, in order to hold .02mm tolerance.

RE