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ee ea To continue with our examination of the little-known world of 3-D in motion pictures, author Bertram starts with an explanation of holography, or photography in 3-D with
lasers. Last month’s installment dealt with
the history of 3-D filmmaking, and the perceptual and psychological factors involved. This month, he concludes with projections on the future and reminders of many of the artistic complications of making films
with an additional visual dimension.
Let the imagination run wild, and get ready for that big step into the holographic movie. And watch that first step...
eee a ee eee eee
film
and the third dimension
Cpart 2)
by John Bertram
Enter the Laser
Holography, holography, holography! So much is being said about this new and complex procedure that it is diffi
cult to put it all into perspective (no pun intended) for the
purposes of this report. Nonetheless, the attempt shall be made.
Put as simply as possible (in order that I not get too confused) each microscopic point of a three dimensional object reflects light waves out in ever expanding “wavefronts ’’. These wavefronts interact with each other and form a complex wave pattern. If this complex wave could be reproduced
Re ORO eye Pe nen reemeMnrMOb nerves ss 2 res eS John Bertram is presently completing studies in the film program at York University. His short films, A Visit, Christmas 1971, And So It Goes and Future Light have won several prizes in student competitions. :
we would have a visual copy of the object itself, in three dimensions, and distinguishable only by touch.
Ordinary photography records only a part of this complex wave pattern: the intensity, or amplitude, of the waves. In order to have a three dimensional image, the “phase variations”, or patterns of interaction between the wavefronts, must also be reproduced. But in order to record these on a photosensitive plate, they must first be converted into amplitude equivalents. This is accomplished by the technique of “interferometry”, in which a photographic record is made of the interference pattern formed when a plane wave intersects with the complex wave. When this recorded “fringe” pattern is illuminated by another plane wave from the same angle, the original complex wave is reproduced, giving a three dimensional image of the original object. This technique is known as “wavefront reconstruction’.
April 1976 / 45