Jean Cabannes (Marseille August 12, 1885 - Saint-Cyr sur mer October 31, 1959) was a French physicist specialising in optics. From 1910 to 1914 Cabannes worked in the laboratory of Charles Fabry in Marseille on the topic launched by Lord Rayleigh at the end of the XIXth century of how gas molecules diffused light. In 1914 he showed that pure gases could scatter light. His career was then interrupted for five years by WWI. In 1919 Cabannes returned to Fabry's laboratory to complete his thesis, after which he moved to Montpellier, and later on to Paris. In 1925 he and Jean Dufay calculated the height of the ozone layer. J. Cabannes, P. Daure and Y. Rocard were among the scientists that, in 1928, discovered that gases diffusing monochromatic light could also change its wavelength. This was identified independently by C.V. Raman and K.S. Krishnan, and by Grigory Landsberg and Leonid Mandelstam. Cabannes was among candidates for the Nobel Prize in Physics of 1929 (proposed by C. Fabry), which was awarded to de Broglie. The 1930 prize went to Raman who gave the complete explanation of the effect now bearing his name, using quantum mechanics.

The lunar crater Cabannes is named in his honor.

A short note in French, by Aimé Cotton, on Jean Cabannes scientific achievements, can be found at http://www.lapasserelle.com/jean_cabannes.htm