Final Project: Laser Dance

Tom McGuire, John Harrison

This project was originally written up here

General idea:

The basic idea is to create a structure which creates visual and audio elements based on its ambient surroundings and
its own internals, both electronically and physically. At the heart of the structure is a laser beam which is controlled
by a mirror. The mirror's angle can be controlled in both the x and y plane by two speakers. This is
a picture of our demo model to experiment with this idea. We are considering trying to modulate the beam and thus
control its brightness with a third speaker.

For our structure we are planning a large, monolith-type sculpture which can be in or outdoors. The structure will
emit sounds, respond to the sounds around it and shoot a laser beam onto, perhaps, the outside of a building. Besides
being our contribution to the ShiftSpace Technology: Art and Sound by Design Final Project Exhibition, we hope it may
draw attention to the exhibition itself by being outside and thus visable and audible (to some extent) within the downtown area.

History:

Manipulating a laser beam using a mirror and two speakers is not a new idea. Most recently the idea has been
realized here and here.
However, we feel that more can be explored not with the technique but with the artistic expression possible with this technique.

Technical Implementation:

Internally we plan to have a laptop running Pd. Our initial Pd patch which we may refine takes sound from a microphone and mixes
it with a cycling sine wave. here is the same patch with low pass filters thrown in. This helps the feedback be low if the structure does not have a natural low resonance. The result is output directly in the left channel and p
hase
shifted in a continually cycling manner in the right channel. The phase shift itself changes in speed and amplitude by two sawtooth waves. Since
all of the wave frequencies are very slow and inharmonic with each other, the sounds will never repeat.

Because the left and right channels are controlling the x and y axes of the mirror which is deflecting the laser beam,
the beam's patterns will also continually change with the sound.

A large speaker will amplify the right channel, making it very audible to viewer/listeners. It will also cause a
feedback loop with the microphone. The microphone also picks up the ambient noise around it, and the images and sounds
are effected by this as well.

The quality of the feedback sound and image is in large part a function of the resonance of the structure itself. In
this way, the structure is in itself defining its own range of sound by its physical makeup.

We are exploring adding a third channel using a second soundcard. The third channel would be connected to a speaker
which moved up and down a plastic rectangle with a hole in it. In its resting state, the laser beam would shoot through
this hole. As this 3rd speaker vibrated, the hole would move and the beam would be modulated. This may allow us to
control brightness.

For testing purposes, we made this pd patch. It allows full control of phase shifts with a slider to see how the laser image shifts accordingly.
Ideally, the structure could be powered internally, say, by a car battery. A built-in charger would allow us to plug it in to recharge the battery.
Tom and John's Diagram

Logochip:

file:schematic

Physical Implementation:

We wish to have a something large and with mass and resonance. We are continuing to explore various possibilities from
a Washington Monument structure to Abdell's Kranae-Aekyad. We
may create a skeleton and then wrap the structure using chicken wire. Or we may make the structure out of styrofoam.