Malus, Étienne Louis

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Malus, Étienne Louis

(ātyĕn` lwē mälüs`), 1775–1812, French artillery officer and physicist. In 1810 he stated his discovery of the polarization of light by reflection and published a memoir of his theory of double refraction.

Malus, Étienne Louis


Born June 23, 1775, in Paris; died there Feb. 23, 1812. French physicist; member of the Paris Academy of Sciences (1810).

After graduating from the Ecole Polytechnique in Paris (1796), Malus entered the engineer corps. As a captain, he participated in the Egyptian campaign (1798) and in the construction of the defenses of Strasbourg (1806-07). Upon his return to Paris he became an examiner and, in 1811, director of the instructional division of the Ecole Polytechnique. Malus discovered polarization of light upon reflection from transparent bodies (1808) and upon refraction (1811, independently of and simultaneously with J. B. Biot). He assigned “poles” to “particles” of light and described as “polarized” those rays in which the particles are oriented identically. In 1810 he established the law by which the intensity of polarized light passing through an analyzer varies (the Malus law). Malus derived a method for determining the direction of the optical axis of a crystal.


“Sur Une Propriété de la lumière réfléchie par les corps diaphanes.” Bulletin des séances de la Société philomatique de Paris, 1808, vol. 1, p. 266.
“Théorie de la double refraction de la lumière dans les substances cristal-lines.” Mémoires des savants étrangeres, 1811, vol. 2, p. 305.


Arago, F. Biografii znamenitykh astronomov, fizikov i geometrov, vol. 2. St. Petersburg, 1860. (Translated [from French].)