Augustin Fresnel

Augustin Fresnel

Augustin-Jean Fresnel (1788–1827) was a French engineer and physicist who made significant contributions to the field of optics, particularly in the study of the behavior of light. His work laid the groundwork for the understanding of wave optics and had a profound impact on the development of optical theories.

Early Life

Augustin-Jean Fresnel was born on May 10, 1788, in Broglie, France. He was the second of four sons in the family. Despite his early interest in mathematics, Fresnel's education was interrupted by the political turmoil of the French Revolution. He later resumed his studies and graduated from the École Nationale des Ponts et Chaussées (National School of Bridges and Roads), where he trained to become a civil engineer.

Career and Contributions

Fresnel's career began in the field of civil engineering, but his interests soon turned to the study of light and optics. His most notable contributions include:

Wave Theory of Light

Fresnel is best known for his strong advocacy of the wave theory of light, which was initially proposed by Christiaan Huygens but had fallen out of favor compared to Isaac Newton's corpuscular theory. Fresnel's mathematical development of the wave theory helped to explain phenomena such as diffraction and interference, which could not be adequately explained by the corpuscular theory.

Fresnel Equations

Fresnel developed a set of equations, now known as the Fresnel equations, which describe the behavior of light when moving between media of different refractive indices. These equations are fundamental in the study of light reflection and refraction.

Fresnel Lens

Perhaps Fresnel's most famous invention is the Fresnel lens. Originally designed for use in lighthouses, the Fresnel lens is a type of compact lens that allows for the construction of lighthouses with much greater light intensity and range. The design of the lens enables it to capture more oblique light from a light source, thereby allowing the light to be visible over greater distances.

Death and Legacy

Augustin-Jean Fresnel died on July 14, 1827, at the age of 39, from tuberculosis. Despite his relatively short life, Fresnel's contributions to optics have had a lasting impact. The principles he developed are fundamental to the field of optical science and engineering. The unit of measure for optical power, the dioptre, is sometimes referred to as the "fresnel" in his honor, and his name is one of the 72 inscribed on the Eiffel Tower.

See Also

• Optics
• Wave theory of light
• Diffraction
• Interference (wave propagation)
• Refractive index