P3D 2&1/2 D

[John Toeppen <toeppen@xxxxxxxx>]

It has been argued that stereophotography is 2 1/2 D.  It has even been
said that we are not holographers.  I partially agree with the first and
personally take exception to the second point.... and expect that others
might too.

Complete volumetric image recording would record each ray of light
reflected off of each and every surface of all sides of the object
captured from each and every perspective. This is not holography.

Holography records the phase and angle of most every wave of laser light
reflected from the object towards the image (film) plane.   The light
waves create fine interference fringes in an emulsion that should have a
thickness of 7 microns or greater.  Fine vanes of refractive index
change are arranged like venetian blinds through the thickness of the
film.  Colors appear that are like the old Lippman plates, just as
transparent soap bubbles adopt colors.  This is just how it records the
data, the human eyes can't detect phase.  To playback beam of uniform
phase is used to illuminate the hologram and the waves of light from the
original object are "decoded" by this "reference beam."

Since there are 50,000 waves of red light (of 633 nm red) per inch
things must be very stable to record such images.  Air currents and
vibrations are major obstacles.  Considerable efforts are often required
to achieve the require 1/4 wave stability requirements.  The films are
slow, so the lasers have to be powerful (Watts not mW) for large images
in photoresist DuPont photopolymer, Dichromated gel, or DCPVA.  However,
I have done good 4x5 silver plates with red laser pointers.  A TEM 00
532nm 1mW green laser pointer "only" cost $300 now from Polaroid Corp. 
I bet the coherence length of that is pretty good.

Anyhow, two photos are not even the same as an object photographed many
times on a rotational table (video at 33 1/3rpm?).

Stereo photography records what we need to see.  Two images, one for
each eye.  Angle and color recorded, no phase requirements, no laser. 
Impressive quality on a molecular level, resolution beyond what we
normally need to see.  Not cheap, just great.  A personal indulgence. 
An art, a science, a reason to go look at the world in search of neat
stuff; eyecandy.

And then the satisfaction of viewing film, the best kind of images. 
Full fovial satisfaction, resolution of the veins of the leaves on the
trees in the foreground, with the deep colors and full detail of sky and
distant mountains.  Or live steam rail.  Hot rods or oceans. There is no
best subject for stereo.  Nor is pure film alone the limit.

I would love to see club's collections on the web.  I would like to see
collections traded, as Dan and I did.  Then I would like to see these
collections gathered and stamped out in volume.  Then I would like to
see these sold to the masses so that they need not be ignorant (of eye
stereo)any more....

Then too, they may just want to wait for it to come out on video
(3&1/2D).

John Toeppen
http://members.home.net/toeppen/


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End of PHOTO-3D Digest 3171
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