Laser light is not a natural form of light; it’s man-made. Laser is actually an acronym for Light Amplification by Stimulated Emission of Radiation.
We use lasers in many things such as DVD players, bar-code scanners at store registers, surgical implements, games, TVs and other devices. Some lasers are used to precision cut all kinds of materials. But one of the most popular ways to experience lasers involves pure entertainment — laser shows!
Arizona Science Center recently installed a new laser system in its Dorrance Planetarium, making it only the second planetarium in the world to display the largest variety of laser special effects. You can see a laser show like never before on the planetarium’s 60-foot full-dome screen.
Here’s an activity for an at-home version of a laser show you can build yourself.
- 1 small food can, empty and cleaned; 4-ounce green chile cans work well.
- 1 balloon
- 2-3 rubber bands
- 1 wood craft stick
- 1 small binder clip
- 1 keychain laser pointer (find at your local dollar store)
- 1¾-inch mosaic mirror tile (find at craft stores)
- Double-sided tape
- Can opener
- Remove the bottom lid of your empty, clean can with the can opener, so both ends are open.
- Cut the neck off a balloon (the top third of the balloon with the opening) and discard it.
- Stretch the remaining portion of the balloon over one end of the can and secure it with a rubber band. Your can should look like a drum.
- Secure the craft stick to the outside of your can with a rubber band. Three quarters of the craft stick should extend past the balloon-covered top.
- Using the binder clip as a wedge under the laser pointer, secure the small laser pointer onto the stick with a rubber band so that the laser is angled upward and the laser point hits the balloon surface when turned on.
- Use the double-sided tape to secure the small mirror exactly over the point where the laser hits the balloon. This will reflect your laser pointer onto a wall or away from you, so please use caution. NEVER point lasers at eyes.
- Turn out the lights, point the can at a blank wall, turn the laser on, hold the open end of the can up to your mouth and sing! You will see fun light patterns form and change on the wall.
The vibrations made from your voice transfer to the balloon and mirror, causing the mirror to shake. The mirror reflects the laser light onto the wall and moves so fast that your brain puts each tiny dot of laser light together as one consistent image (wonky circles, figure eights, etc.). This is called persistence of vision and is the same principle for how flip books, cartoons and movies work.
Professional laser shows use computer-controlled mirror movements to give precise and elaborate shapes of the reflected laser light (usually timed to music), but the basics are the same.
What happens when you make a really low sound or really high-pitched sound into your laser can? What happens if you hold your can up to a speaker playing music? Try different experiments, and be sure to send me pictures of your build!