Understand Lasers in One Minute

Then make your own death ray in five

A ruthless DJ vaporizes innocent party-goers with death lasers (not really). Public domain.

Quick background info

Laser is an acronym for “light amplification by stimulated emission of radiation.” If it sounds like complete gibberish, read it again at the end.

When an atom is excited, its electrons rise to higher energy levels. When the electrons fall back down, they release the energy as photons (light). Depending on how much they fall, different light is released. That’s why some things make pretty colors when they burn.

Sometimes, an atom releases more than it was given (amplifying it). Lasers work because of this fact.

Ok, now start the clock.

1. Trap some atoms between two mirrors.
2. Stimulate them with some energy. Get them really riled up!
3. Some of the atoms emit more than they were given. These extra photons will excite other atoms and get duplicated again and again.
4. The photons bounce wildly between the two mirrors. Since one of the mirrors is only 99% reflective, some escape!
5. Only perfectly parallel photons escape, which is why laser light is a beam.
6. Enemy vaporization time.

More information

• (text) HyperPhysics: Lasers
• (video) Axis of Awesome: Learning About Lasers with Veritasium

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