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On Sun, 14 Jan 2018 23:37:16 -0500,
wrote:

On Sun, 14 Jan 2018 22:09:37 -0500, wrote:

45 years ago I was in a bar in Chicago and they had a laser deal that
plotted the 2 channels of the sound system as a Lissajous pattern on
the back wall.
I tried to make one using an old Neon laser and mirrors on speaker
drivers about 40 years ago. It was almost working when the free used
laser I had crapped out. Now that laser diodes cost less than a stick
of gum I wanted to try again. What is the best way to steer the laser?
Piezo crystal or some kind of mirror solution

===

I'm not an expert on piezo crystal optics but I think you'll have more
fun engineering an electromechanical linkage to a mirror. It will
also be more intuitive and use readily available components.

That was my thinking before I started working on laser printers but
these days it is a pretty mature science and those parts may be as
cheap as lasers. I found out the first time down the rabbit hole, you
need a 1st surface mirror. A regular silver on glass mirror creates a
ghost image. I ended up with a dental mirror sans handle, epoxied to a
coil spring with arms going out to 2 small speaker cones 90 degrees
out. The laser I had was a neon, about 1.5" in diameter and a foot
long that needed a HV power supply to spark up. These days you can get
a diode that runs on 4.5vdc. Just about the time I got the geometry
right, my laser broke.
I came up with another laser down here but it was pressed into service
at the flower store and went with the store. That design was still a
little funky and I wanted to try something different.
I really don't believe that in the 70s they were using a crystal tho.
We did us one in a 3800 but it only deflected in one axis.
I may be missing a whole different concept in steering a laser. I
thought Richard may have dabbled in this stuff.