🚀 go-pugleaf

      The low rent approach to this problem is to glue a mirror to the
cone of an old loudspeaker.  You can produce interesting but not meaningful
patterns in this way.  A setup with two mirrors, one for X and one for Y,
allows positioning.  Connection to a pair of D/As with DC-coupled power amps
provides computer control, or connection to an audio system provides 
decorative patterns.  Don't expect much precision.

      The high rent approach is feedback-controlled mirror galvanometers
from General Scanning Corporation.  These have a mirror, a galvanometer 
movement, and a variable capacitor for position feedback.  This is how
the laser-show people do it.

					John Nagle