Hi
I think by this tou are meaning galvanometers.  They cost more than servos
to get decent ones and I am not planning any serious shows with the
equipment.  As I said before, it is mainly a demo of computer control of
the beam.  By using servos, I can turn the project into something else when
I am finished.  As for raster and other scanning methods, it is way too
complex for a short project.  I saw the tomorrows world program a while
ago.  They projected a flower didn't they?


Tim Kerby

At 10:51 12/12/97 +0000, you wrote:
>I believe that for the kind of thing you describe, the lasers are
deflected by
> cunning gadgets.
>
>You know how a simple ammeter works: they're like that except the needle is
> replaced by a tiny mirror.
>The laser shines at a mirror, and angular deflection is proportional to
current.
>The light beam becomes a very long zero-mass needle!
>You still have the inertia of the coil and mirror, but this is still a lot
> faster and simpler than steppers
>
>You use a pair to scan in x and y directions.
>
>What kind of show did you have in mind?
>The arrangement above can generate nice Lissajous figures.
>
>If you want to do some kind of raster scanning, then typically you'd use a
> rotating octagonal mirror to do the
>repetitive sweeps. Tomorrow's World showed this principle with a mix of red
> green and blue lasers to produce a
>cinema type of display. Always focused too.
>
>


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