Fresnel lens

Fresnel lens, 1968. In 1822 a French physicist named Augustin Fresnel invented a lens that would make his name commonplace along the sea coasts of Europe and North America. It looked like a giant glass beehive with a light at the centre.The lens could be as tall as twelve feet with concentric rings above and below to bend the light into a narrow beam. At the centre the lens was shaped like a magnifying glass, so that the concentrated beam was even more powerful. Tests showed that while an open flame lost nearly 97% of its light, a flame with reflectors lost 83% of its light, the Fresnel lens was able to capture all but 17% of its light.Because of its amazing efficiency a Fresnel lens could easily throw its light 20 or more miles to the horizon.