3D

[William Maddox]

--- On Fri, 10/8/10, Fred Cisin <cisin at xenosoft.com> wrote:

> > Wow!  How?  Using a display capable of
> rendering actual depth?
> 
> I warned you that it was CRUDE, . . .
> You looked into a dark cabinet, in which there was a moving
> mirror,
> reflecting a CRT.  The image would change according to
> the position of the
> mirror.  When it was moving fast enough, persistence
> of vision would give
> you a visual image in which parts of the image were
> actually different
> distances!   I think that the images were
> chosen for maximum suitability.
> I never saw a commercial implementation attempt.

I once saw a product announcement for a commercial 3D display
that used a flexible varifocal mirror.  If you've ever seen one
of those things that makes a coin inside appear to be floating
in space just inside an opening at the top, you've seen how a
concave mirror can manipulate apparent depth. From the diagrams/photos, 
it looked like the device used the acoustic wave from a hi-fi speaker 
to drive the mirror.  The image was provided by a vector display,
limited to wire-frame graphics, and there was likely some electronics 
or software to compensate for the distortion introduced by the optics.
It was a big box, somewhat reminiscent of both a radar console and an arcade game.  If I recall correctly, the tube was mounted overhead,
and you looked down into the mirror at its reflection.

--Bill