दिनविशेष १४ जुलै

दिनविशेष १४ जुलै

Augustin-Jean Fresnel

French physicist and engineer, reviver of wave theory of light, inventor of catadioptric lighthouse lens

Death - 14 july 1827

Augustin-Jean Fresnel (/ˈfrɛznəl/ FREZ-nəl, /freɪˈnɛl/ fray-NEL; French: [ɔɡystɛ̃ʒɑ̃ fʁɛnɛl]; 10 May 1788 – 14 July 1827) was a French civil engineer and physicist whose research in optics led to the almost unanimous acceptance of the wave theory of light, excluding any remnant of Newton's corpuscular theory, from the late 1830s until the end of the 19th century.

But he is perhaps better known for inventing the catadioptric (reflective/refractive) Fresnel lens and for pioneering the use of "stepped" lenses to extend the visibility of lighthouses, saving countless lives at sea. The simpler dioptric (purely refractive) stepped lens, first proposed by Count Buffon and independently reinvented by Fresnel, is used in screen magnifiers and in condenser lenses for overhead projectors.