P3D Re: PHOTO-3D digest 2839

[Bob_Maxey@xxxxxxxxxxxx]

>>I was interested in Ken Dunkley's to Bob Maxey's post that not all
>>holograms reproduce the whole view from a broken fragment. We have a
white
>>light reflection hologram at work of a piece of netsuke (Japanese ivory
>>carving). Which got broken by accident and each piece shows only part of
>>the carving ,like Ken says it is an image plane hologram with part of the
>>image apearing in front of the plate.


What creates a holographic image, is the collision of light waves. It is
referred to as interference patterns. to oversimplify, a laser beam is
split. Part of the laser beam strikes the recording medium and part strikes
the recording medium after being reflected off the object. Some systems
vary a tad from this, but this is the basic idea. It is in these recorded
interference patterns that a true 3D image is produced. What complicates
the discussion is the various types of holographic images available.
Dichromate images, embossed holographic images; produced from a master,
like a record by pressure. there are what are called Stereo parallax
stereograms and multiplex holograms as well.

Some are white light holograms and some are viewed by laser light. We all
are familiar with the images produced on mylar. Usually, they are created
by stacked artwork in layers.

As far as your Holo of the carving, the entire image is still there.
However, and this was not mentioned in my original post, the image is
degraded to some degree. however, under proper conditions, the entire image
can be reconstructed - quality will not be as good as it was originally.
The name Holograph roughly translates to Whole Image.

Also, holographs are recorded on many new materials that yield sharper
images and faster exposure times. There are new films available and a
number of polymers that are being used. Agfa recently discontinued their
film.


>>Although I suspect that a hologram
>>appearing as a virtual image just behind the plate may not show the whole
>>view if broken either. It may have to be some distance behind the plate
for
>>the whole object to be seen through part of it as would be the case with
a
>>real object.
>>Another slightly nit -picking point Bob-Maxey used the term
>>holograph , in the UK at least that term has to be avoided in favor of
>>hologram as the term holograph is already used to describe an authors
>>original draught in their own handwriting.


Holography, Hologram, holographic, it is all the same. You are very astute
to point out that a Holograph is a term for a hand written manuscript in
the author's own hand. but I see lots of holographic images and they come
from as far away as Russia, and the terms are used interchangeably. I
prefer the term Holographic Image.


After working with these items for some time, I have a large collection
from many different manufacturers. I will try to answer questions if anyone
is interested.

RM



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End of PHOTO-3D Digest 2840
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