Re: Late evening thoughts on stereo formats

[P3D Gregory J. Wageman <gjw@xxxxxxxxxx>]

Greg Marshell replied:

>I'm not sure what Dr. T assumed, and I haven't yet had time to check out
>what a "vectograph" is, but what I meant is like a lenticular print in
>that left and right are combined into one image.

If I remember correctly, the vectograph is a print made with polarizing
inks, sort of like an anaglyph, but polarized.

>Indeed, I think backlit transparencies is a great way to display most
>photography.

I've always like the look of backlit transparency, too.  It's a common
technique at trade shows in booth displays.

There's a simpler way to implement your viewer, though.  Put the
transparancies side-by-side with a polarizer in front of each.  In front
of one (say, the right), place a front-surface mirror at a 45 degree angle
and in front of the left, place a half-silvered mirror also at a 45
degree angle.  The front-surface mirror reflects the right image onto
the half-silvered mirror, which re-inverts it and combines it with the
direct-viewed left image.  The polarization remains to keep the images
separate at the viewer's eyes.

           Left    Right
          image    image
         ------- --------
         ------- -------- <= Orthogonal polarizers
            |  /     |  /
            | /      | /
            v/       |/
            /<-------/
           /|       /
          / |      /
         /  v     /

         ^        ^
         |        |
      Half-      Front-surface
 silvered mirror    mirror

This is a rather old technique and I don't take credit for inventing
it.

        -Greg W.


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