Origin of the Safeview lens
America’s first lighthouse used a system of silvered reflectors to intensify the main light source, a whale-oil lamp. But, by the 1850’s, the government authorized use of a technology new to U.S.: the glorious, multiprismed lens invented in France by Augustin Fresnel (pronounced Fray-nell) in 1822.
It was a marvel....a complex array of dazzling glass prisms and bull’s-eye lens mounted in a gleaming brass framework. Each lens cost $12,000 at the time plus shipping costs from France.
The Fresnel lens was much more efficient at collecting and directing the light rays and produced a beam five times more powerful than the reflector system used previously. But, to take maximum advantage of the higher light intensity, the light had to be placed high enough to compensate for the curvature of the earth. When mounted at 100 feet above sea-level, it had a visible range of up to 18 miles at sea.
Fresnel lenses can now be economically stamped or moulded out of transparent plastic and are used in a variety of situations, including being responsible for the optical effect of the Safeview lens.
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