Jules Antoine Lissajous

Jules Antoine Lissajous, date and photographer unknown.

Jules Antoine Lissajous (March 4, 1822 - June 24, 1880) was a French mathematician, after whom Lissajous figures are named. Among other innovations, Lissajous invented the Lissajous apparatus, a device which creates the figures that bear his name. In it a light is shone (or laser beam) off a mirror attached to a vibrating tuning fork, which is then reflected off another mirror attached to another, perpendicular vibrating tuning fork (usually of a different pitch, creating a specific harmonic interval), then onto a wall, which resulted in a Lissajous figure. This led to the invention of other apparati such as the harmonograph.