Set up all the stuff you collected onto a table near a blank wall, preferably a white one or one painted a light color.
Turn off the lights.
Aim the laser through the objects and/or off the surfaces. Watch what happens to the laser dot.
Try jiggling the laser in your hand – what happens?
Try moving the objects around – what happens?
Try combining objects (ex. boucing it off a reflective surface and through a transparent one) – what happens?
Lasers are just very concentrated beams of light. And, because light acts like a wave, it behaves in certain ways. Two of these are key to making a homemade laser show:
Diffuse Reflection: Light bounces off of mirrored surfaces. In the case of lasers, if you bounce the beam off a flat reflective surface, it will bounce out in a single beam at the same angle it entered. BUT, in the case of some surfaces, the light being reflected spreads out into multiple points of reflection. THAT is diffuse reflection and it is why you can see “rainbows” on the surface of a CD or DVD.
Diffraction and Refraction: When light passes through some transparent objects, like a flat piece of glass, its direction may change (that’s called refraction and we’ll deal with it more in a future Mr. O), but still comes out otherwise unaffected. This is why you can see just fine through a glass window. But, in some transparent materials, especially ones that aren’t perfectly transparent or that have unusal shapes, the light is spread out and broken into multiple beams. That is called diffraction and is why you sometimes see a rainbow of light when it passes through a prism or water.
By using diffraction and diffuse reflection, we can create mini-laser shows by shining them off of and through various common household objects. Just make sure to add some tunes to make the show complete!