In 1999, in my Physics 534 class, my teacer, Camille Gagnon
(his website),
made a demonstration with rotating mirrors and a laser which projected
nice patterns on the wall. I had been very impressed, I had decided
to do the same thing eventually.
By using mirrors fixed to dc motors, I have been able to
reproduce the same effects.
Pictures
One the pictures, left to right, we see:
How I glued the mirror to the first motor. (It's a mirror with the reflecting material on the surface instead of behind the glass.).
Only the first mirror spinning.
Both mirrors spinning.
Above are the patterns obtained when both mirrors are spinning in the
same direction.
If the two mirrors are spinning in opposite directions,
flower patterns are obtained, as above.
Disclaimer
I cannot be held responsible for any damages that could occur to you
or your equipment while following the procedures present on this page.
Also, I GIVE ABSOLUTELY NO WARRANTY on the correctness and usability
of the informations on this page. Please note, however, that the procedures
above have worked in my case without any damages or problems.