The summer of 1960 saw the world's first demonstration of an entirely
new source of light, which on the other hand, is so concentrated and powerful
that it can produce power densities billions of times as inteuse as those on
the surface of sun, and, on the other hand, can be controlled so precisely
that surgeons use it to perform many delicate operations on the human eye.
The beam from this new device can burn holes in steel and set carbon on fire,
and it has many remarkable features apart from its powe, it spreads out so
little that if it were sent from the earth to the moon it would illuminate an
area of the moon's surface only by two miles in diameter. It is very pure,
all the light in it being of the same wavelength, and it is coherent which
means that all the light waves in the beam are exactly in phase with each
other, these last two properties may not seem remarkable-they may not even
mean much to most people but to scientists and engineers they are very important
for the technological benefits they bring.
The name of the new instrument is the laser, from the initials of light
Amplification by Stimulated Emission of Radiation-the process taking place
inside it. In the few years since 1960, the laser has become well known as a
weapon in the armory of james Bond's enemies and other film villains or heros.
More important , it has given rise to a whole new technology. The tremendous
expansion in its use is evident from the fact that at the end of 1964 only
two hundred eye operations had been carried out anywhere in the world with
lasers, while 18 months later one American Company could claim that fifty one
thousand people had undergone eye surgery with the lasers it had produced.
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