Physics 2000 Einstein's Legacy Lasers

Lasers

Lasers are used to cut precise patterns in glass and metal, to reshape corneas to correct poor vision, and to provide intense heat in controlled fusion experiments. But we also use lasers as very precise light sources in supermarket checkout lines, CD players, and to transmit most telephone signals.


But what is a laser? How is laser light different from regular light?

You can figure this out by playing with different kinds of light in the demonstration below. Notice how the distance between peaks, the "wavelength", changes with the color.


With laser light all the crests and troughs line up with each other.

Yes that means that all the light is exactly the same color. We call that "monochromatic".

But the laser light has a second thing that is special. All the waves are going in the same direction. It is much more "orderly" than the other light.

That is exactly what makes laser light special. It is very organized waves with all the light exactly the same color and going in exactly the same direction. We can also think of light as little particles. With a laser these particles come in a perfectly uniform stream all going in the same direction. Because it is so orderly we can control laser light extremely well, and that is why we can use it to do so many things.

Cool. But now I want to find out how we produce light like that...

Lasers Atom/Light Interactions Population Inversion Creating a Laser


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