Augustin Jean Fresnel

Augustin Jean Fresnel [ oɡystɛ ʒɑ fʀɛnɛl ] ( born May 10, 1788 at Broglie (Eure), † July 14, 1827 in Ville d'Avray, near Paris ) was a French physicist and engineer, who significantly to the creation of the wave theory of light and contributed to optics. He studied both theoretically and experimentally the behavior of light.

Life

Fresnel was the son of an architect and as a child suffered from a severe learning disability, so he could not read at age nine. At thirteen he entered the École Centrale in Caen, and at sixteen and a half the École Polytechnique, where he graduated with honors of the engineer. Then he went to the École Nationale des Ponts et Chaussées. He worked as an engineer for the department of Vendée, Drôme and Ille -et -Vilaine. But as he had supported the Bourbons, he lost his job in 1814, when Napoleon came to power again. In the second restoration of the monarchy he obtained a post as engineer in Paris, where he spent much of his remaining life.

His research in optics, which he continued until his death seem to have started around the year 1814, when he was preparing an article on the aberration of light, which, however, was not published. In 1818 he wrote an article on diffraction for which he in the following year the prize of the Académie des sciences in Paris received (see also Poisson spot). In 1823 he was unanimously elected member of the Academy. In 1825 he was elected as a Foreign Member of the Royal Society of London, from the Rumford Medal he was awarded in 1824. In 1819 he was appointed Secretary of the Commission for lighthouses for which it was first designed Fresnel lens as a replacement for the previously used mirror. He died near Paris of tuberculosis.

The wave theory of light, demonstrated experimentally for the first time by Thomas Young, has been extended to a large class of optical phenomena and permanently established by his brilliant discoveries and mathematical deductions. By the use of two flat metal mirrors, arranged at an angle of almost 180 ° from one another, he avoided in the experiment by Francesco Maria Grimaldi ( 1618-1663 ) by the use of covers for the light transmission occurring diffraction. This he could carry in a convincing manner the interference phenomena in accordance with the wave theory calculation. In addition to this experiment, Fresnel has also become known for his interference experiment with the biprism.

With François Arago he studied the laws of the interference of polarized rays. He produced circularly polarized light using a Glasrhombus, known as Fresnel rhomb, having obtuse angles of 126 ° and acute angles of 54 °. His works on questions of optics learned during his lifetime only little public recognition, and many of his articles have been printed by the Académie des Sciences until years after his death. But as he wrote in 1824 to Young, " the sensitivity or the vanity, love of glory is called " was blunted in him. "All the compliments I have received from Arago, Laplace and Biot never prepared me so much pleasure as the discovery of theoretical truth, or the confirmation of a calculation by experiment. "

1969 was proposed by the French side, a unit of frequency ( a terahertz ) to name in his honor with Fresnel, but this was never implemented. According to him, the Fresnel number is named, which gives a measure of the strength of diffraction at an aperture.

Fresnel is immortalized among the 72 names on the Eiffel Tower.

Deonyme

Fresnel's name was in the following terms ( Deonyme ) Input:

• The Fresnel integrals are special improper integrals.
• The Fresnel formulas deal with the degree of reflection of electromagnetic waves.
• Fresnel lenses with much less glass also generate short focal lengths as conventional lenses.
• The Fresnel zone plate can be used by diffraction and interference for X-rays.
• The Fresnel zone describes a spatial region between transmit and receive antenna of a radio link.
• The Fresnel Biprismaversuch is an experimental arrangement for generating interference of light rays from a divergent light source.
• The Fresnel double mirror also generated are capable of interference of light rays from a divergent light source.
• 1969 France proposed Fresnel as the unit of frequency before.
• The Fresnel parallelepiped is an optical prism with a 45 ° linearly -polarized light can be converted into circularly -polarized light.
• The Fresnel entrainment coefficient was used to calculate the speed of light in moving media.
• The Fresnel number describes how much is the diffraction of a light beam at a panel.