Laser display (was Re: Orlando hamfest)

From: der Mouse <mouse_at_Rodents.Montreal.QC.CA>
Date: Tue Feb 15 11:30:58 2005

>> the foundation for a Laser MAME rig (who wants to play "Star Wars"
>> on the living room wall? Anyone?
> Now THAT would be cool, but I'd rather play Asteroids. Wonderful
> monochrome vectors - much cheaper :)


> If you wanted to do Star Wars, you'd probably need to rig up a DPSS
> green laser and some form of blue laser to do it properly. With
> Asteroids you just use a red laser pointer :)

If I had colour, I'd do Tempest. I have a (very hacky) setup for
playing Tempest, using keyboard keys for the buttons, a spinner with
breadboard-built interface circuitry connected to a parallel port for
the knob, and a SPARCstation with a cg6 for the display (the cg6 does
line-draw in "hardware" (likely really firmware)), a hacking-up of the
MAME Tempest module.

However, remember that you can do lissajous figures easily with speaker
"motors", since both deflection signals are sine waves. A game like
Tempest or Asteroids or etc requires _very_ high acceleration rates out
of the deflectors, or you get things like rounded corners, and very
good linearity, or you get non-straight lines. You also need to be
able to do at least several thousand, probably several tens of
thousands, of lines per second to get reasonably flicker-free displays.
It's hard enough to do all that with electronics, never mind with
physical devices.

If I wanted to do this sort of thing, I'd look for a substance whose
index of refraction changes with applied voltage and build prisms out
of it, to use as the deflectors. (This is more difficult for colour.
For that I might simply build three of them and then have some very
careful alignment procedures to get registration right on the display
surface.) It might be enough to use mirrors on piezo actuators, but I
wouldn't count on it without testing it.

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Received on Tue Feb 15 2005 - 11:30:58 GMT

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