| Jules Antoine Lissajous | |
| Birth Date: | 1822 3, df=yes |
| Birth Place: | Versailles, France |
| Death Place: | Plombières-les-Dijon, France |
| Nationality: | French |
| Fields: | Physics |
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| Thesis1 Year: | and |
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| Known For: | Lissajous figures |
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Jules Antoine Lissajous (in French pronounced as /ʒyl ɑ̃twan lisaʒu/; 4 March 1822 in Versailles – 24 June 1880 in Plombières-les-Dijon) was a French physicist, after whom Lissajous figures are named. Among other innovations, Lissajous invented the Lissajous apparatus, a device that creates the figures that bear his name. In it, a beam of light is bounced off a mirror attached to a vibrating tuning fork, and then reflected off a second mirror attached to a perpendicularly oriented vibrating tuning fork (usually of a different pitch, creating a specific harmonic interval), onto a wall, resulting in a Lissajous figure. This led to the invention of other apparatus such as the harmonograph.