INFOGRAPHICS – In 1822, Augustin Fresnel presented a lens that would revolutionize maritime signalling. By channeling light into a narrow beam, his invention dramatically increases the range of headlights.
For the signal of a lighthouse to be perceived from very far away, it must first be emitted from a tower high enough so that it overcomes the earth’s curvature. This is the geographical scope. It results from the technical prowess of engineers from Ponts et Chaussées and workers, who in the 19th or 20th century built these buildings often at the risk of their lives. The construction of the lighthouse of Ar Men, nicknamed the hell of hells, lasted nearly 15 years. Then, the light rays must travel long distances despite the turbulence of the atmosphere. This is optical range.
The Fresnel lens
This article is for subscribers only. You have 80% left to discover.
Pushing back the limits of science is also freedom.
Keep reading your article for 1€ the first month
Already subscribed? Login