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PROFESSOR: We're
now going to look

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at another laser,
the argon laser.

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It's much more powerful
than a helium-neon laser.

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In fact, it can put out
several watts and even

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several tens of watts,
principally, in the blue,

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in the green, and also
in the ultraviolet.

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In this first
demonstration, we're

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going to take the output
of this argon laser here,

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and, without focusing it,
we're going to send it

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onto a piece of cardboard.

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And we want to show
you what happens.

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Now, here you see
the argon laser.

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It puts out about 2 watts
or so in the blue and green.

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The blue is around
4880 angstroms,

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the green is around 5145,
and other weaker wavelengths,

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both in the visible and
also in the ultraviolet.

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You can't see very
much of the laser,

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so what we're going to
do is take the top off

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so you can get a closer look
at what's inside this laser.

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Here is the argon laser
without the top on.

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It certainly looks
very complicated.

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But I'll try and help
you along by identifying

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some of the important
features in the laser.

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And we'll do this in close-up.

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So first, let's zoom in to
the left side of the laser,

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where we see the
mirror mount that holds

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one of the laser mirrors.

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So the mirror is
held down there.

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And then the air path between
the mirror and the discharge

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tube is sealed with
bellows over here.

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And here is, then, the
beginning of the discharge tube.

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Here you see the cathode--

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the big cathode--
for this laser.

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The bore of the tube
is inside this magnet.

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So you can't see it.

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And then there is
this magnet here

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that provides a
longitudinal magnetic field.

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So here is the magnet.

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And then the anode
is located over here.

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Now, because this is a
powerful arc discharge,

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both the bore and the
magnet are water-cooled.

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Over here, you see
that the discharge tube

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is terminated with a
window at Brewster's angle.

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And, finally, the
second mirror is

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mounted in this hole over here.

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Now, we're going to turn
the power on and look

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at the output.

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Now, the argon laser
puts out a lot of power,

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as I said, around 1 or
2 watts from this laser.

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And one thing you
don't want to do

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is get in the way of the beam.

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Now, here, we see a
piece of cardboard

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that's unlucky enough
to be in the way of even

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an unfocused beam.

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So if we turn up the
power in the argon laser,

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you see what happens.

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You see a nice hole burnt in
and lots of smoke comes out.

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And this is, remember,
the unfocused beam.

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We have about 1 watt of power.

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And here is the
hole we just burned

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in the piece of cardboard.

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Looks pretty bad.

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And, remember, this is
the unfocused argon beam.