Physicist and engineer — Étienne-Louis Malus (Paris, 1775 – Paris, 1812) was a French physicist, mathematician and military engineer. An officer of the corps of engineers, he took part in Napoleon’s Egyptian campaign before devoting himself to the study of optics. In 1808 he discovered the polarisation of light by reflection, observing through a calcite crystal the light reflected from the windows of the Luxembourg Palace. He formulated the law that bears his name, describing how the intensity of polarised light varies when passing through an analyser. His studies contributed decisively to understanding the wave-like, transverse nature of light, later developed by Fresnel and Young.
Trivia
The discovery of polarisation came about by chance: one evening Malus looked through a crystal of Iceland spar at the sunset light reflected from the windows of the Luxembourg Palace and noticed that, on rotating the crystal, the image darkened.
Theories and contributions
- Malus’s law — The intensity of polarised light after an analyser depends on the square of the cosine of the angle: .
- Polarisation by reflection — Light reflected from a surface can be partially or totally polarised.
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Linked atoms
2 linked atoms.