Jules Antoine Lissajous (1822-1880) - Jules Lissajous, a French physicist and mathematician, investigated the relationships of sound frequencies, waves, and vibrations. In 1850, his doctoral thesis was based on vibrating bars using Chladni's sand patterns and nodal theories. Lissajous began his experiments with sound waves and vibrations by using tuning forks in water and noting the ripple patterns from different applied frequencies.

Lissajous also developed a method for visualizing the waveforms created by vibrations. This optical method of capturing vibrations is represented in his well-known Lissajous Figures. These figures were created by reflecting a light beam from mirrors on two tuning forks vibrating at right angles. The images of these light beams as they reflected off the mirrors were captured on a screen.



Before the onset of digital technology, Lissajous Figures were used to represent the frequencies of sound waves in radio signals. This was accomplished by observing the pattern a signal of unknown frequency created when it was combined with a signal of known frequency.

Oscilloscope displays, showing the ratios of two or more frequency signals in horizontal and vertical axes, are visual examples of Lissajous Figures, represented by repetitive oscillatory motions containing the two perpendicular directions of different frequencies. The resulting paths of the oscilloscope waveforms depend on the ratio of frequencies and the phase difference.

In 1873, Jules Antoine Lissajous was awarded the Lacaze Prize for his scientific contributions to our understanding of sound.[2]


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