I first created this device to amaze my friends as we discovered the joys of psychedelics. It produces a variety of smooth flowing shapes on surfaces. These shapes move, and often appear to rotate in threespace. The effect can be choreographed by any computer with stereo sound and an audio amplifier. It can be built for a pittance from spare parts.
This is not a scientific instrument, so don't expect precision! Furthermore, I won't insult your intelligence by giving you specific mundane details about dimensions and orientations.. mine is just a big wad of hot glue. There are many ways to pull off the design successfully.
First, glue a magnet chip onto the back
mirror, along a short edge..
Split the rubber band into two equal pieces. Glue a piece to the back
of each mirror
along its other
short edge, like this:
So now you have made hinged
mirrors which the electromagnet
s can tug
on. See where I'm going with this?
The next step it to unite a mirror with an electromagnet. The idea is to get the mirror's magnet chip in front of the electromagnet's business end (about 1/4 inch away), using only the tightened rubber band to mount the mirror. This way, the mirror can swing freely in one dimension, actuated by the electromagnet. After this is done, try pushing on the mirror to see if the magnet chip will stick to the electromagnet. If this happens, it's not good! Try tightening the rubber band or putting a dab of glue on the magnet chip.
Now make another of these magnetmirror devices with the other electromagnet and mirror. One device will control the X position of the laser beam, while the other will control the Y position. Mount one of the magnetmirrors to a flat surface so that it's mirror swings vertically. This is magnetmirror Y.
Now for the trickiest part of the project... You will need your laser, the other magnetmirror, and some patience. You need to mount both the laser and the second magnetmirror on the same surface as magnetmirror Y. This second magnetmirror is X, so it needs to swing horizontally instead of vertically. The laser must be mounted in such a way that it bounces off one mirror, then the other, then out of the device. Experiment with different positions of magnetmirror x and the laser, and be careful to see what happens when the mirrors are swung to different angles. There should be no mirror position where the beam doesn't hit both mirrors and leave the device. Got it? (I'll try to work on a better explanation of this someday.) Once you have found the positions, hot-glue everything together very decisively.
Now your device is finished! But how do you control it? Consider the physics of this device. If you put a sine-wave (try 30-60hz) into one of the electromagnets, its mirror will swing back and forth, producing a straight line of light on your surface. If you put a sine wave into one magnetmirror and a cosine wave (of the same frequency) into the other, you will get a circle or oval. Putting different frequencies into each axis will give a variety of smooth flowing shapes. Sweeping frequencies will make the shapes morph together. Another interesting effect is this: Each magnetmirror has its own unique resonant frequency. If you put a wave of this frequency (or some multiple of it) into the magnetmirror, Its mirror will swing very strongly and produce interesting effects. Be careful with this though. (See: Tacoma Narrows Bridge for an explanation of the dangers of resonance.)
I choreographed my first trippy laser show using an Amiga computer and Protracker music software. I attached the LEFT speaker-out to magnetmirror Y, and RIGHT to magnetmirror-X. I used a sine-wave instrument, and sequenced a "song" to control the laser. (You could also use a whistle sample because that is pretty sinusodial.) I tried feeding real music into the device, but the results were not nearly as spectacular.
The night I unveiled the laser device, It was astounding!