Theatre Design & Technology - Fall 1978 - 11

"If a high-power laser were fo
sfrike a viewer direcfly in fhe eye,
fhe refina would burn before fhe
eye could close. "

Rear-screen projection of laser effects (patterns) is quite
common for use in films. The concepts of laser effects, and
the effects which are actually available, are changing rapidly,
and a film company often finds itself in the beginning stages
of production with a small rear-screen, and the producer, director, and special effects man watching a potpourri of laser
effects, watching and waiting for the ones which might fit into
the mood of the particular scene. It was this sort of procedure
first followed in Logan's Run. After a few sessions the special
effects people were able to choose the desired patterns, film
them from the rear-screen, and then later superimpose the
laser effects over the chosen scenes of the film.
Laser effects can also be projected directly onto the actors.
This was done in two films for which I consulted, Lipstick and
Demon Seed, using a half-watt argon laser. Strict precautions
must be taken in order to avoid hitting the eyes of the actors
with the raw laser beam during rehearsals and while testing
the diffraction effects since even a half-watt laser can burn the
retina. Once the patterns are engaged, however, and the raw
beam is dissipated by the optics of a laser projector, then the
danger is greatly reduced. If the players are moving, any laser
light which might strike them does so very fleetingly. Greater
precautions should be taken when using higher power lasers
and when the beam is not wholly dissipated by the optics of
the projection system.
The sophistication and complexity of laser projectors vary
enormously. Some package shows consist of no more than
pieces of shower curtain glass, several diffraction gratings,
and a series of mirrors and beam-splitters. Other projection
systems include several sets of scanning mirrors for each
color or line out of the laser. A krypton laser, for example, has
many possible lines of color and is usually operated with
broad band mirrors. The raw beam, which appears to be
white, is sent through a prism which bends and separates the
different lines of light. Each line of light can then be sent to a
set of scanning mirrors, one of the set vibrating in the vertical
axis and the other in the horizontal. These mirrors, when
electronically signaled, can create various complicated patterns (lissajous) and, if able to scan rapidly enough, are able
to draw out names and logos onto a screen or into fog or
smoke. With the rise of high-rate scanning and sophisticated
computer electronics to drive the mirrors, the images are

limited only by the imagination.
Los Angeles-based Laser Images, Inc., is the major producer of laser entertainment. Their shows, Laserium and
Laserock, were first presented in Los Angeles four and a half
years ago and the success of both shows, which combine one
two watt Krypton laser effects with music, demonstrates the
viability of an all-laser production.
As this type of sophisticated technology becomes more
widespread, obvious applications include multi-media shows,
trade shows, and amusement parks. Of course, the existing
use of laser effects for discotheques, rock concerts, movies,
and television should expand rapidly as the technology advances.
The large laser and logo system are ideal for grand openings, sports events, special occasions, and the like, and in the
very near future we will undoubtedly see a quick burgeoning
in this area of laser use. The higher power argon laser which
uses predominantly short and mid-range wavelengths is used
for larger projections, although the power of the raw beam in
a twenty-two watt laser tends to melt the mirror coatings on
the steering and scanning mirrors and also heats the mirror
substrate to such a degree that the mirror warps, thus expanding the beam and making it very difficult to control.
Specially coated mirrors must be created for these lasers. If
the ambient light levels can be controlled sufficiently, however, no more than a one or two watt laser should be necessary.(lf a high-power laser were to strike a viewer directly in
the eye, the retina would burn before the eye could close.)
Holography has a growing application in the entertainment
area, and an entire field of display holography has grown out
of early holographic work. There are now several types of
holograms, each with its own special application and display
characteristics. Of particular interest for film and theatre are
the multiplex type, and the large display hologram available
in both virtual image (image appears behind hologram) and
real image (image in front of hologram).
The multiplex hologram or intergram, first developed by
Lloyd Cross of San Francisco, is really a hybridization of
motion picture and holographic techniques. It is, very simply,
the integration of a multitude of 35mm motion picture frames
using holographic techniques. It is especially fascinating because it incorporates motion (although not real time), and

In order fo be appreciafed in
fheafre producfion ... holograms
musf be quife large and fhe cosfs
rise proporfionafely ... "
USITT/Fall. 1978

Theatre Design & Technology

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