The Laser

The laser is one of the most advanced tools we have in our
civilization. Lasers are powerful enough to cut through a
thick piece of steel, yet can be used in medicine to
perform delicate surgery. 

The inventions of the laser which stands for light
amplification by stimulated emission of radiation, can be
dated to 1958 with the publication of the scientific paper,
"Infrared and Optical Master" by Arthur L. Schawlow.
Theodore H. Maiman then built the first laser, a ruby that
produced bursts of red light. Maiman first operated his
laser in 1960. 

A laser is a device that creates and amplifies a narrow,
intense beam of coherent light. In a laser, the atoms or
molecules of a crystal, such as a ruby or garnet --or of a
gas, liquid, or other substance -- are excited in what is
called the laser cavity so that more of them are at higher
energy levels. Reflective surfaces at both ends of the
cavity permit energy to reflect back and forth building up
in each passage. 

Lasers now range in size from semiconductor lasers as small
as a grain of salt to solid-state and lasers as large as a
storage building. The light beam produced by most lasers is
pencil-thin and maintains its size and direction over very
large distances. 

Lasers are widely used in industry for cutting and boring
metals and other materials, in medicine for surgery, and in
communications, scientific research and holography. They
are an integral part of such familiar devices as barcode
scanners used in super markets, scanners, laser printers,
and compact disk players. 

Since laser beams could easily be adversely affected by
atmospheric conditions such as rain fog, low clouds, and
objects in the air, such as birds, scientists and engineers
suggested a number of novel schemes to protect the light
from interference, including shielding it in metal and
thermal gas lenses to navigate around bends. 

It took a major innovation, the development in the early
1970's of hair thin strands of encased glass, called fiber
optic waveguides before the laser could transmit telephone
signals. Since then, optical fiber has become the medium of
choice for telecommunication companies to transmit voice,
data, and video.
 
The potential for lasers developed faster in the field of
medicine after Kumar Patel invented the carbon dioxide
laser which permitted surgeons to perform intricate surgery
using photons rather than scalpels; performing operations
that a few years ago were almost impossible to perform.
Shorter lasers are being used to "weld" detached retinas.
 
Lasers are very important and are becoming more and more
advanced. Scientist are still trying to find new ways to
harness the power of the laser. 
 
Bibliography:
 
Townes, Charles H. How The Laser Happened: Adventures of a
Scientist. Oxford University Press, NY, 1999.