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October 1968 Electronics World
 Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
from
Electronics World, published May 1959
- December 1971. All copyrights hereby acknowledged.
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In this 1968 "Macs
Service Shop" story titled "The Laser - Toy or Tool?," Mac educates Barney on lasers, from Einstein's 1917
stimulated emission theory and
Townes &
Schawlow's
1958 optical maser to
Maiman's 1960 ruby crystal laser using a mirrored rod pumped by flash tubes
for coherent, narrow-beam red light. He highlights properties like focusability
(1/10,000th cm spot), minimal divergence (200 ft at 25 miles), and applications:
surgery (retina welding, scalpels), metal cutting, ICBM/satellite defense,
precise ranging, gyroscopes, altimeters, auto modeling, 118-mile / 10-TV-channel
communications, high-speed holography for 3D TV, erasers, potato peelers, chalk
lines, tattoo removal. Schawlow predicted office/factory/home ubiquity in 20
years, with a market at $300M/year then and to $1B/year by 1975 (laser market
exceed $16B in 2023). Mac (aka John Frye) accurately predicted things like
lasers revolutionized medicine (LASIK), industry (cutting/welding), navigation
(gyroscopes), telecom (fiber optics), LIDAR/autos, and holography/AR.
Mac's Service Shop: The Laser - Toy or Tool?
 By John T. Frye
The laser promises to exceed even the cathode ray scope in terms of usefulness
and versatility.
"Mac," Barney said to his boss, "what's all this big deal about lasers? Seems
as though I can't pick up a magazine these days that doesn't mention them. Last
night I suddenly realized that I've only a very vague idea of what a laser is or
what it can do. Do you suppose you can help clear away any of the smog?"
"I can try," Mac replied, taking his pipe from his pocket and loading it. "How
far back do I have to start?"
"Better just start at the beginning," Barney answered. "Just assume I'm a complete
idiot about lasers and you won't be far wrong."
"Okay. In that case we may as well begin with 1917 when Albert Einstein observed
that an atom or molecule stimulated by an electromagnetic wave should temporarily
absorb energy that would be given off subsequently as light when the particle returned
to its unexcited state. Experiments proved him right, and in 1958 Charles Townes
and Arthur Schawlow dreamed up a device they thought could be made to produce an
intense stream of photons -- the basic units of light -- by stimulating molecules
of gas confined in a cylinder.
"Since the device was actually a variation of Townes' Nobel Prize-winning invention,
the maser, which produced microwaves by a process called "microwave amplification
by stimulated emission of radiation," they called their invention an "optical maser."
In 1960, T. H. Maiman, researcher for the Hughes Aircraft Company, used their theory
to build the world's first working laser that emitted bursts of intense red light.
"Instead of a gas, Maiman used a synthetic ruby crystal grown in molten aluminum
oxide to which a pinch of chromium had been added to provide the crystals with a
chromium atom for every 5000 aluminum atoms. The resulting crystal, in the form
of a slender ruby-red rod, had both ends highly polished and silvered to form mirrors.
One end was heavily silvered to make it highly reflective, while the other was silvered
more lightly to cause it to be partially transparent. A flash tube, similar to that
used in strobe lights, was wrapped around the rod in the form of a coil.
"When the flash tube was fired, the intense light it gave off excited the chromium
atoms of the crystal, and their electrons shifted to paths farther from their nuclei
than normal. When these electrons fell back into place, photons of light were emitted.
Some escaped through the transparent walls of the rod, but others hit the mirrors
at either end and were reflected back towards the other end. In their ping-pong
excursions, the photons stimulated other chromium atoms into emitting photons, and
finally the gathering, surging stampede burst through the partially silvered end
of the rod in an intense pulse of red light. Since this light was tremendously more
powerful than the light from the flash tube that triggered it, we had "light amplification
by stimulated emission of radiation," or a laser.
"Laser light differs in important ways from ordinary light. For one thing, it
has a very narrow frequency range, and it is coherent."
"Hold it!" Barney interrupted. "That's the word I keep stumbling across in all
laser articles. What does it mean ?"
"It means the resonant cavity action of the space between the mirrored surfaces
of the crystal has marshaled the photons into plane wavefronts before they escaped.
They are working together like oarsmen in a racing shell. Not only does this greatly
intensify their collective strength, but it also keeps their parallel rays from
diverging. The beam that emerges from the end of the 1/4" rod spreads to a width
of only 200 feet at a distance of twenty-five miles. Maiman says, in principle,
the laser can generate a beam less than a hundredth of a degree of arc."
"Modern laser light isn't always red, is it ?"
"No. Using different techniques and materials, scientists can produce laser beams
in a spectrum of wavelengths all the way from infrared to blue. They can also be
produced continuously or in pulses. While that synthetic ruby was the first substance
to "lase," over a hundred different gases, glasses, plastics, semiconductors, and
liquids have now been teased into producing laser beams by "pumping" them with flashes
of light, high-voltage discharges, the injection of a stream of electrons, or even
through the use of chemical agents."
"I still can't see why a laser is so super," Barney complained. "It makes a pretty
bright light, and the way it's produced is pretty neat, but what's it good for ?"
"The raw power that can be packed into a beam of light, the fact the light beam
contains a very narrow band of frequencies that permit it to be precisely focused
and used in making precise measurements, and the ability to maintain a very narrow
beam over great distances -- these are the important properties of the laser," Mac
replied.
A laser beam can be focused into a spot only 1 /10,000th of a centimeter wide,
and that tiny spot burns billions of times brighter than the sun's surface. It can
punch holes through steel plates, can "weld" a detached retina in a human eye, and
can cut through flesh like a surgeon's scalpel and cauterize the smaller severed
blood vessels as it goes. Since the beam actually exerts pressure on a surface on
which it impinges, it has been proposed that powerful laser beams be used to push
back into orbit satellites that have begun to fall toward the earth, or even to
generate enough heat to melt an incoming ICBM before it can reach its target.
"Keep in mind that a laser wavelength is only about 1 /1000th as long as the
microwaves used in conventional radar. This makes laser altimeters, range finders,
and aerial mappers extremely accurate. Honeywell recently developed a laser gyroscope
that employs laser beams instead of a spinning rotor to sense rotation, thus doing
away with the friction and drift of conventional gyros. Explorer 22 carried aloft
a 10-lb array of fused silica glass mirrors that reflected back to earth a tracking
laser beam. With this device it was possible to locate the satellite within ten
feet at a distance of 600 miles. Two Japanese firms, Hitachi Ltd. and the Mitsubishi
Electric Corp., are exploiting at shorter ranges this ability of a laser beam to
resolve linear measurements accurately. The equipment translates the contours of
clay automobile models into digital dimensional data. Changes in contours detected
by the laser are recorded on tape that can be processed by a computer to generate
control programs for the automatic milling of stamping dies. This materially
reduces the time needed for new auto designs to get from the styling studio to the
production line.
"The rare-earth gallium-arsenide semiconductor laser devised by R. N. Hall of
General Electric Company is especially interesting. It is easily excited to laser
action with efficiencies up to 75% and is responsive to simple caloric, magnetic,
or electric- potential control of modulation and frequency. That makes it ideal
for use in communications, and desert distances up to 118 miles have been spanned
by communication over such a laser beam. The Air Force Avionics Laboratory at Wright-Patterson
AFB has developed a single-laser communications system that can carry ten TV channels
simultaneously.
"The use of the beam as an illuminant also has some interesting possibilities.
For example, a laser beam in combination with a spinning mirror camera and a Kerr-cell
shutter has produced framing rates exceeding one million per second and individual
exposure times of less than 30 nanoseconds. And very recently it has been discovered
that if an object is illuminated with two lasers of different colors and a holographic
picture is taken of the object, a full -- color three -- dimensional picture can
be reproduced with ordinary light shining through the film. The reproduced image
seems to float in space, and if the observer moves, he changes his field of view
just as if he were observing a real object. This may well be the forerunner of 3D
color TV.
"Physicist Schawlow insists lasers are still very primitive devices." "They're
still about at the crystal stage of radios, or airplanes around 1910," he says and
goes on: "Laser technology has come a long way, but it still has a hell of a long
way to go."
"He thinks that in no more than twenty years the laser will be a common tool
in the office, the factory, and in the home, where it may be used to peel potatoes
and as a pilot light for kitchen stoves. To make his point, he has built and will
soon market a laser eraser, a model of which he has already attached to his typewriter.
When Schawlow makes a mistake, he pushes a button and the laser beam vaporizes the
dark energy-absorbing typed letters and leaves the energy-reflecting white paper
unscarred with no eraser rubbings to be brushed away.
"The thin, perfectly-straight beam of a laser makes a wonderful "chalk -line"
for tunnel builders and other construction workers. It can even remove a tattoo
design from human skin. The laser ray penetrates the translucent white skin with
little harm but vaporizes the darker dye pigment beneath. In the same manner a laser
beam can weld a broken lead inside a vacuum tube without damaging the glass envelope."
"Okay, okay! I'm convinced a laser is a perfect chalk line, an extremely ac-
curate micrometer, a welder, a punch press, a radar, a gyroscope, a high-speed camera,
a super-duper coaxial cable, a bloodless surgical knife, an eraser, a potato peeler,
and a producer of optical illusions," Barney exclaimed. "That thing has more uses
than a zipper!"
"You'll get no argument out of me about that," Mac said. "It reminds me very
much of the cathode-ray oscilloscope. When that first came out, it seemed little
more than a laboratory toy; but it soon moved on to the production line as a test
instrument, went to war as a radar display device, came into the home as the heart
of black-and-white TV and then color TV, and proliferated into dozens of different
versions.
"The laser seems destined to follow in its footsteps. At first, as Maiman put
it, the new light source seemed `a solution seeking a problem,' but it is finding
those problems with ever-increasing frequency and is solving them. Even now lasers
are a $300 million a year business, and this is expected to grow to a billion-dollar-a-year
business by 1975."
"I'd like to make a final small contribution to this discussion," Barney declared.
"I read recently that several authorities are calling for stricter safety around
lasers. Split-second exposure of the eye to a laser beam is all it takes to cause
permanent burns to the retina or even blindness. In the laboratory lasers have produced
fatal hemorrhages in the brains of mice. Several agencies are investigating hazards
that may threaten workers around lasers. That pretty pencil of colored light is
like the pretty little coral snake: it's nothing to fool around with!"
Mac's Radio Service Shop Episodes on RF Cafe
This series of instructive
technodrama™
stories was the brainchild of none other than John T. Frye, creator of the
Carl and Jerry series that ran in
Popular Electronics for many years. "Mac's Radio Service Shop" began life
in April 1948 in Radio News
magazine (which later became Radio & Television News, then
Electronics
World), and changed its name to simply "Mac's Service Shop" until the final
episode was published in a 1977
Popular Electronics magazine. "Mac" is electronics repair shop owner Mac
McGregor, and Barney Jameson his his eager, if not somewhat naive, technician assistant.
"Lessons" are taught in story format with dialogs between Mac and Barney. There
are 131 stories as of January 2026.
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