Etienne-Louis Malus (23 July 1775 - 24 February 1812) was a French officer, engineer, physicist, and mathematician. His mathematical work was almost entirely concerned with the study of light. He studied geometric systems called ray systems, closely connected to Julius Plücker's line geometry. He conducted experiments to verify Christiaan Huygens' theories of light and rewrote the theory in analytical form. His discovery of the polarisation of light by reflection was published in 1809 and his theory of double refraction of light in crystals, in 1810. Read more