Fresnel, Augustin Jean 1788-1827
French physicist

Born in Broglie, he was head of the department of Public Works in Paris. His intensive study of the problem of projecting well-defined beams of light led to the celebrated multi-faceted lighthouse lens (the 'Fresnel lens'). His experimental and theoretical investigations into the interference, diffraction and polarization of light, coupled with his facility with new mathematical ideas, contributed greatly to the establishment of the undulatory theory of light. He also invented a special prism ('Fresnel's rhomb') to produce circularly polarized light. His most brilliant papers were a series published in 1818-21 relating polarization phenomena to Thomas Young's hypothesis of transverse waves, and his ?uvres Compl�tes ('Complete Works') published in three volumes in the 1860s, contain practically everything that was known in optics up to the time of his death.