Hey Ray! Trapping laser light

PITTSBURGH (KDKA) — If you have ever used a laser to point at things, or to play with your pets, you may have noticed that laser light travels in a straight line. We are going to try an experiment that will essentially capture a laser beam. To know that the beam is trapped, our experiment will bend the laser beam. If you are wondering why we can't we just use a mirror to reflect it, a mirror would just cause the beam to bounce into another straight line. We want the beam to go in curved path, so we know that we are trapping the beam.

To do this, we have an old, plastic pop bottle with water in it, something to poke or drill a hole in the bottle, and dish to catch the water. We also need a laser. The laser we used is one is a little more powerful than the ones you use to play with your pets.

You can try to use a traditional laser pointer for this experiment, though. Also, you never want the laser to shine in anyone's eyes. Since laser light can cause eye damage, this experiment should only be conducted under the supervision of a responsible adult.

For our experiment, we are going to shine the laser through the bottle of water. We want a hole in the bottle where the laser shines to the other side. The laser shines easily through the bottle, but once the stream of water starts, you will notice the beam do something different.

The laser light stays trapped in the stream of water, even as the stream curves downward.

This happens because of how light reflects differently within different substances. When the laser light shines through something denser, like the water, the light reflects where that denser water meets less dense air. This bouncing and reflecting keeps occurring over and over inside the stream.

This is called Total Internal Reflection. It is also an example of how fiber optics work!