Augustin-Jean Fresnel (1788–1827)

Augustin-Jean Fresnel

1788 Augustin-Jean Fresnel was born at Broglie, France. He was a French engineer and physicist who contributed significantly to the establishment of the theory of wave optics. His father was an architect and led him to a closely related profession.

1804 When he was 16 and half years old he was accepted to Polytechnic School that he graduated getting the title of engineer of bridges.

1814 Until this year he turned different assignments as an engineer. Because of a rebellion act against the emperor he was fired. He continued to have activities related to Physics.

On the 28th of December he wrote to a friend: „I do not know what is meant by light polarization; please my uncle M. Merime to send me the works that can clarify me”. Eight months after this, he had done important discoveries for this domain.

1819 He got the Academy of Sciences award for researches regarding light diffraction.

1823 He was accepted among academics.

1825 Royal Society in London chose him among its members.

1827 Royal Society offered him Rumford medal. 

Fresnel’s first researches were related to the double refraction phenomenon. The phenomenon studied by Huyghens was known, by which an incident light beam was divided into two beams by an Iceland spar crystals or by quartz. After many experiments, Fresnel concluded that the majority of crystals support the double refraction phenomenon that is more or less emphasized. Then he performed the double refraction phenomenon using as circumstance a compressed glass prism. So he demonstrated that the double refraction is determined by the existence of an unequal structure of the birefringent material in different directions.

Grimaldi (1665) had observed the first the possibility of interference of two light beams. Hooke had searched by this phenomenon, unclear yet, the explication for colourful iridescence that was noticed to soap bubbles; in fine, Young (1802), researching the phenomenon, took into account the phase difference between the overlapping oscillations. Fresnel has the merit of leading so good the experiment so that to allow him to establish a complete theory on interference phenomenon, precisely establishing the conditions it can happen. He firstly stated that the phenomenon can take place only within identical rays, videlicet of the same colour (the same) and having the same refractive index (η); these rays must start from the same point, from the same source and to browse different distances. By the device called “Fresnel’s mirrors” interference conditions were created. To explain diffraction, Fresnel started from Huyghens’ principle that he completed with the idea of interference of beams that start from distinct sections of wave front. Using the intuitive method of zonal construction (1818), he explained the light rectilinear propagation and the deviations that this propagation suffers close to obstacles, namely, he explained the diffraction phenomenon. Completing Huyghens’s principle with the interference notion, Fresnel gave to this principle a physical meaning. Huyghens-Fresnel principle allows the study of the problem regarding the intensity of light diffraction problem settlement.

The last Fresnel’s works, done in collaboration with Arago, are related to light polarization. They determined the conditions when the two polarized rays can interfere. Fresnel explained the rotating polarization phenomenon, considering it a special form of birefringence.

Polarized light study led Fresnel to the conclusion that the light beam is transversal, fact that, together with other observations, led to cosmic ether hypothesis leaving.

1827 He died being 39 years old, at Ville D’Avray, near Paris, because of tuberculosis.

During his short life, he contributed a lot to the development of Knowledge regarding light phenomena and his name is connected forever to the great discoveries of Physics field. Fresnel’s mirrors, formula, biprisme, Fresnel areas and Huyghens-Fresnel principle abundantly confirm the information above.[1]

 

 

Bibliography:

    1. Augustin-Jean Fresnel (1788 – 1827), ro.biography.name

 

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