Lasers have been shown in Science Fiction movies for a long time. Just like many inventions, they were first theorized and then made quite a while ago (the first working examples were in the 50′s!). Since then, lasers have been added to nearly every invention, revolutionizing entire industries (music, medical, etc.). Have you ever wondered how a laser works? What makes a laser different from a regular light? If so, read on.
What does “laser” mean?
First, laser actually stands for “light amplification by stimulated emission of radiation.” If you can understand that at face-value, you can pretty much figure out how lasers work. Since most people just skip over phrases with too many big words, I’ll break it down.
How is a laser different from a light bulb?
Photons (light energy) are released when an electron goes from a higher level orbit to a lower level orbit. That’s why heating something up causes it to change color; some of that heat is being released as light energy. I did a post about different types of lights and explained how they work in a fairly nontechnical manner. Essentially, they all work by exciting electrons, which go up in orbit and then release a photon when they drop in orbit. The difference is that “normal” lights do this pretty randomly, but lasers are more organized (amazing how much more you can accomplish if you are organized, isn’t it?).
What makes it so bright?
When photons are released, the energy level is what determines the color (frequency). If you can get all of the photons released at the same energy level, they build upon each other and are a much brighter, more focused beam of light. Inside a laser, this is done by having two mirrors. When a photon is released, it bounces back and forth between the mirrors, which causes other photons to be released if their electrons are stimulated at the same level. Essentially, it is like having one person on a boat running from side to side screaming, “Come on, this is fun!” Other people start to go along with him and the boat starts rocking. Eventually it capsizes and they drown, but that’s another story…
All these photons are rushing back and forth between the mirrors, convincing other electrons to let their photons out to enjoy the fun. Meanwhile, one of the mirrors is not completely a mirror (kind of like how you can just barely see through some one-way mirrors on the mirror side) and some of the photons escape. Enough of them keep bouncing around to continue causing other photons to do the same, but the ones which do escape are all of the same frequency, making them a very intense light.
How can lasers be used?
All kinds of devices use the laser in difference ways. For instance, CD players shine the laser onto the spinning CD, which has tiny grooves in some places. The parts that are flat (no grooves) reflect the laser back to an optical sensor, but the grooved parts do not. Since digital media only needs ones and zeros to represent data, the flat spots become 1′s and the grooved spots become 0′s.
What does it mean again?
Once again, the acronym is “light amplification by stimulated emission of radiation.” Now it should make a bit more sense. The light (photons) is amplified (because the photons are all at the same frequency) by stimulated emission (meaning the electrons are all stimulated to produce that same frequency of light) of radiation (which is simply the process of releasing energy as waves and/or particles).