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  While the device may have spe-
cialized use in commercial TV
studios, this application remains to
be evaluated by industry experts.
Because the light emitted from
the laser TV camera comes from a
single source, the lighting effects
are similar to those of a photo
taken with a flashbulb; the effect
of many light sources from dif-
ferent angles is not possible with
the presently developed system.
Laser scans from several different
points are conceivable but might
prove impractical from the stand-
point of cost. Single-source illum-
ination, however, may prove com-
pletely adequate for some uses
such as "spot" TV news reporting.
  Another potential use is that of
an all-weather landing aid for
aircraft. The device could be used
as a direct vision video "radar" ef-
fective from an altitude of several
hundred feet. Runways or heli-
copter landing spots can be readily
marked off with reflective paints
or tapes. These would give energy
returns to the laser receiver with
several hundred times the intensity
of the surrounding terrain. Such a
landing aid would be especially
valuable in remote military bases
as in jungle or other dense areas.
For helicopter landings, landing
sites could be quickly indicated
by ground crews using portable
makers.
  An operational landing aid sys-
tem would employ a relatively
powerful continuous beam laser
and a "tracking aperture" receiver.
  Laser TV has potential as a
means of covert surveillance for
law enforcement agencies. As used
in the present system, the laser
beam's fast scan speed and low in-
tensity combine to make it virtu-
ally invisible, so that dark areas
such as doorways could be
scanned at night without the
knowledge of those observed.
With a properly tailored system it
would be possible to observe per-
sons at distances in excess of a mile.
  In the field of science, a number
of applications such as studies of
the nocturnal habits of animals
may be feasible.
  In the present system red light
emitted by a helium-neon gas laser
is used to scan the subject through
a pair of rotating, diamond-faceted
mirrors. The fast line sweep of the
JANUARY, 1966
   Perkin-Elmer Laser TV would prove useful as a pilot's direct vision landing
aid effective from a few hundred feet altitude until after touchdown. The
use of
special retro-reflective runway markings
times greater than normal materials.
transmitted laser beam is synchro-
nized with the electron beam of a
standard television picture re-
ceiver, and laser light energy re-
flected from the subject is sensed
by a self-contained receiver. The
energy returned from the subject
controls the intensity of the elec-
tron beam of the TV monitor's pic-
ture tube, forming the image. The
very low useful energy emission of
about one milliwatt from the dem-
onstrator unit has proved adequate
for imaging objects about 30 feet
distant.
  Performance and range capa-
bility of all forms of this system
could be tremendously enhanced
by utilizing the new argon green-
beam lasers, which provide output
powers of several watts. Other
laser wavelengths also could be
employed.
  Versions of this type of system
also could have application as a
lunar or planetary landing aid for
spacecraft. For close-range use the
simpler helium-neon    lasers are
preferred.
  Lasers, first developed in 1961,
are a source of brilliant, pure, co-
herent and monochromatic light.
The name laser is the acronym for
Light Amplification by Stimulated
Emission of Radiation. Lasers of
various types have been devel-
results in energy returns several hundred
oped, some of intense power which
virtually emit "bullets" of light
which have a life of only a fraction
of a second. The gas laser used in
the present TV system is of far
lower power but emits its pure
light beam continuously.
    SUSPENSION BRIDGES IN
         HALF THE TIME
  Bethlehem Steel Corporation re-
cently announced it has developed
a method for the fabrication of
suspension bridge cables which
will speed erection of these struc-
tures and outmode the present
time-consuming practice of "spin-
ning" these cables wire-by-wire.
  The newly-perfected process
makes possible manufacture and
socketing of brridge strands having
parallel wires within the manufac-
turer's plant, and the transporta-
tion of these prefabricated strands
on reels to the bridge site for rela-
tively speedy erection.
  Engineers claim that the new
development will "significantly re-
duce" the construction time re-
quired for major suspension
bridges, with important financial
advantages to the bridge owner in
terms of reduced debt interest
charges and earlier toll collections.
  Time and money savings, they
point out, will depend upon a num-
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