Have you ever wondered why you just can’t just shine a flashlight through a lens and call it a laser? It’s because of the way a laser generates light in the first place.
The word LASER is an acronym for Light Amplification by Stimulated Emission of Radiation.
That’s a mouthful. Let's break it down.
Let's do an experiment that shows you how a laser is different from light from a flashlight by looking at the wavelengths that make up the light.
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Materials:
- laser such as these: https://amzn.to/3FAog5f
- diffraction grating or old CD
- flashlight
- clear tape
- red, green, and/or blue fingernail polish
Download your student worksheet here! This download was provided by Laser Classroom.
Lasers are optical light that is amplified, which means that you start with a single particle of light (called a photon) and you end up with a lot more than one after the laser process.
Stimulated emission means that the atom you’re working with, which normally hangs out at lower energy levels, gets excited by the extra energy you’re pumping in, so the electrons jump into a higher energy level. When a photon interacts with this atom, if the photon as the same exact energy as the jump the electron made to get to the higher level, the photon will cause the electron to jump back down to the lower level and simultaneously give off a photon in the same exact color of the photon that hit the atom in the first place.
The end result is that you have photons that are the same color (monochromatic) and in synch with each other. This is different from how a light bulb creates light, which generates photons that are scattered, multi-colored, and out of phase. The difference is how the light was generated in the first place.
Radiation refers to the incoming photon. It’s a word that has a bad connotation to it (people tend to think all radiation is dangerous, when really it’s only a small percentage that is). So in this case, it just means light in the laser. The incoming photon radiation that starts the process of stimulated emission (when the electron jumps between energy levels and generates another photon), and the light amplification means that you started with one photon, and you ended up with two. Put it all together and you have a LASER!
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The light blox are no longer available, but you can use laser pointers such as these: https://amzn.to/3FAog5f
The downloaded worksheet says we need A red, green and blue Light Blox with slit caps, * One red and one green LASER Blox. What are these things and where do we get them?