Thursday, July 26, 2012

Fresnel Lens, Montauk Pt. Lighthouse Museum

The Fresnel lens was invented in 1822 by French physicist Augustine Fresnel as a way to convert the scattered light rays from a light source into a single, powerful, beam of light via a series of glass prisms arranged in concentric rings around it that redirected the scattered rays through a central lens that itself was shaped to further magnify the light passing through it. Tests indicated that a single flame lost 97% of its illumination without any re-direction. With reflectors, it still lost 83%, but with the new invention, only 17% was lost, thus making it perfect for seacoast applications. Depending on its size, the Fresnel lens can cast beams as far as twenty miles.

Early light sources were oil burning lamps that created a great deal of soot, thus requiring frequent cleaning in all types of weather and conditions, a daunting task for the lighthouse keepers charged with their upkeep. You also didn't want to break anything, either.

The Fresnel lens has had a great impact on photography as it is utilized for its ability to shape light on commercial sets for still and motion picture photographers worldwide.

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