Laser galvo mirrors: perfect instrument for the demonstration of Lissajous figures

Abstract

A pair of galvo mirrors reflecting light from a laser pointer is suggested for use as a school demonstration of Lissajous figures. The device is small, cheap and easy to assemble. Combined with a two-channel waveform generator, a full spectrum of excellently stable Lissajous figures can be generated (concerning frequency ratio, amplitude ratio and initial phase angle difference). The operation at frequencies faster than the vision persistence allows us to draw the figures on a normal projection screen or on a wall. When operated with a violet laser pointer and a thermoluminescent foil, the frequencies can be decreased and the advance in figure drawing can be followed. The memory effect of the thermoluminescent foil also enables us to record and observe several Lissajous figures simultaneously.

Demonstrating beat phenomenon and Lissajous figures with hard disk drive voice-coil motors

“…When the oscillating frequency is high enough, the Lissajous curve can be displayed on other screens rather than phosphorescent foil due to the visual persistence effect. Polác ˇek et al used the laser galvo mirrors to show the Lissajous figures on a normal projection screen or a wall [6]. The simpler the curves, the higher the oscillating frequency, resulting in a higher scanning rate of the curves.…”

“…Lissajous experiment displays the compound oscillation visually with the light beam reflected from the oscillating mirrors driven by tuning forks. Today, the Lissajous experiments can be repeated easily with the electromagnetic-driven oscillating mirror and the laser [3][4][5][6]. Naturally, the experiment about traditional oscillating mirrors can be demonstrated with the modified VCM component.…”