Augustin Jean Fresnel

French physicist. Famous for research in wave optics theory.

[ Born: 1788 / Broglie, France. ]

[ Died: 1827 / Ville d'Avary, France. ]

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• 1821 - Proved mathematically that light could only have a transverse component, as this was the only way to explain polarisation.
• Used mirrors instead of aperatures, (to avoid diffraction effects), to conclusively explain the phenomenon of light interference.
• Developed the “Fresnel equations” which describe the movement of light through media of different refractive indices.
• Invented the “zone plate”, which focuses light via diffraction instead of refraction.
• Credited with discovering “Fresnel diffraction” or near-field diffraction – the phenomenon which occurs when a wave passes though an aperture and diffracts in the near field.

Trivia - In 1819 Fresnel became the commissioner for lighthouses in France and created a special type of lens, the “Fresnel lens” to substitute for more expensive mirrors.

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