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Ah... That's right - the other projector didn't have galvos, just spinning mirrors. But yeah, setting one laser to hit the mirrors at a shallow angle while the other is aligned to a sharper angle will make the relative pattern sizes different, also giving you the circle-within-a-circle effect.
Adam
i hate to say your wrong again, but... LOL
its not a circle in a circle, there the same size just ext to each other but when i took the pic it turned out like that
Hmmm... Interesting.
I've done several experiments with the spinning mirror effect, including the two laser idea, and one of the problems I had was making sure that the path each beam took between the two mirrors was roughly equal. If the path lengths weren't equal, then one beam would draw a larger circle (off the first mirror only) than the other beam would, and the patterns would be *slightly* different. I assumed that you had the same thing going on, only on a much larger scale.
Then again, I was using a home-made rig with fairly large mirrors to begin with, and I probably had more "wobble" on the mirrors than I needed. Thinking back on it now though, the small differences I noticed were probably about as bad as they could ever get with that sort of setup.
Then too, if you have small mirrors to start with you can't hardly get them too far miss-aligned or the beam won't hit the second mirror at all. Evidently that's the arrangement you have in your projector.
Still, it is hard to tell that the circles are not concentric from the pics. It's a cool effect!
Adam
a few more pics and videos to help you all out on how i got the effect
http://i80.photobucket.com/albums/j1...s/DSCN2824.jpg
http://i80.photobucket.com/albums/j1...s/DSCN2822.jpg
http://s80.photobucket.com/albums/j1...7082006006.flv
http://s80.photobucket.com/albums/j1...7082006004.flv
http://s80.photobucket.com/albums/j1...t=27082006.flv
Very Cool, Wherer did you get this laser ufo from?
its called a crab and i got it from maplin - www.maplin.co.uk
there are lots of them on ebay to