Physicist and engineer — Augustin-Jean Fresnel (Broglie, 1788 – Ville-d’Avray, 1827) was a French physicist and engineer, among the principal architects of the wave theory of light. An engineer with the Corps des Ponts et Chaussées, he devoted himself to optics in an almost amateur fashion, but with revolutionary results. By developing a mathematical model of diffraction and interference, he showed that light phenomena can be explained by assuming that light is a wave, superseding Newton’s corpuscular theory. He also understood that light is a transverse wave, thereby explaining polarisation. He applied his knowledge in designing the stepped lenses that bear his name, still used in coastal lighthouses today.
Fun fact
When Fresnel presented his wave theory, the mathematician Poisson objected that it absurdly implied a bright spot at the centre of a disc’s shadow; the experiment instead confirmed exactly that spot (known as the ‘Poisson spot’), turning the objection into proof in Fresnel’s favour.
Theories and contributions
- Wave theory of light — Explains diffraction and interference by treating light as a wave, via the Huygens-Fresnel principle.
- Transverse nature of light — Light is a transverse wave, which accounts for polarisation phenomena.
- Fresnel lens — Thin stepped lens that concentrates light with little material, used in lighthouses.
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Linked atoms
2 linked atoms.