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Lasers are, like light bulbs, widely used and just as under
appreciated. They are used in everything from laser pointers and advanced
weapons targeting systems, to laser eye surgery and even high-tech laser
microphones. Also like light bulbs, they are very complicated to
understand and produce. |
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But
what actually are lasers? The phrase LASER is an acronym; it stands for
Light Amplification by Stimulated Emission of Radiation. I don’t know the
textbook definition of what that means, but what happens is that light is
bounced between two mirrors, one of which is a “partially silvered”
mirror; it lets some light through, but most is bounced back. Each time
the light is bounced back, it passes through a special substance that,
when photons hit it, enters an “excited” state. These “excited” particles
zoom around and, when they hit another particle, release a photon. In this
example, two photons (the ones that excited the particles) have become
three! So, essentially, the light level is always increasing and
decreasing at the same time. It is increasing because the substance is
amplifying (not focusing) the light, and decreasing because some light is
escaping through the mirror. It is a very ingenious device, the laser. |
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This
is all very well and good, you might say, but what practical uses are
there for a laser? There is an alarming amount of uses for a laser. CD
players, CD-ROM readers in computers, distance finders, almost all
manufacturing plants, and those things I named above all use lasers.
Distance finders work by sending a short burst of laser light and timing
how fast it takes to come back. CD players and CD-ROM readers work in a
similar fashion, bouncing light off of CDs, which have many small ridges
on them, and then timing how fast and in which direction the light is
reflected. Manufacturing plants use lasers to cut sheets of metal when
precision is needed. Ultra-high intensity lasers can quickly melt the
hardest sheets of metal. Sort of like being warmed up by the sun, but
multiplied by one thousand. Futuristic laser microphones work by bouncing
a laser beam off of a pane of glass, and, like with the CDs, measuring
when and how much the beam moves. Laser eye surgery is pretty much welding
and scorching specific spots in the eye.
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