The word "laser" is an acronym for "light
amplification by stimulated emission of radiation." What
does it mean? In short, a high energy atom can be stimulated to
release light that is in phase (in step, or matching) a wave that
hits it, thus amplifying the stimulating wave. When billions and
billions of atoms do this at once, they produce a monochromatic
ray of light where all the waves are in step with each other.
This is a great advantage in applications that require a focused
and concentrated beam of light. In science too, the monochromatic
nature of this light (being of a single wavelength) makes it easier
to use in experiments.
When lasers were first invented in 1960, no one knew
what to do with them. Today, you can find them almost everywhere,
from the CD players, to supermarket barcode scanners, to surgery
tools, to the Mars Sojourner Rover, which used laser rangefinding
to avoid running into rocks. One application that promises to
vastly improve the Internet you are using to view this site is
fiber optics. Because of its high frequency, light can carry massive
amounts of information. (Just compare what you see through your
eyes with what you hear!) However, until the laser was invented,
light usually spread out, diffused, and generally got blurred
so that at large distances no information could be extracted.
With a laser beam, the light is very bright, monochromatic, and
tightly focused. This helps a laser beam carry for great distances.
(Scientists bounced laser beams off the moon!) However, for earthly
destinations, air, dust, and objects will often get in the way
of a laser beam, preventing it from traveling too far. That is,
until fiber optics were invented. Fiber optics are simply thin
strands of ultra-pure glass. Due to the angle of incidence, there
is total internal reflection for a laser beam traveling down this
strand of glass, and thus, most of the light arrives intact at
the other end, delivering vast amounts of information.
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