Our Lissajous exhibit uses a laser galvanometer to create Lissajous curves on a distant target. In addition to generating these special curves, an audio amplifier and speakers are provided to generate the tones corresponding to each note, allowing users to correlate sound to the curves. The curves are controlled using two keyboards next to the galvanometer, one for each axis of the curve. Entering the same note on each keyboard will produce an ellipse with an aspect ratio (ellipticity) related to the timing of the note inputs; for equal frequencies (same notes) the tilt and aspect ratio is related directly to the relative phase of the two notes. Entering different notes on the two keyboards will produce a more complex curve, with complexity increasing with increasing note differences. Up to four notes can be entered on each keyboard to generate even more complex curves. There is a hold button on each keyboard to sustain up to four-note inputs.
sound frequencies, frequency and phase measurement, musical play
Science North, Sudbury, Ontario, Canada