The Fresnel Lens

View of Fresnel lens and view from Bodie Island light tower
Fresnel lens and view from Bodie Island Lighthouse

National Park Service

Developed by French physicist Augustin Jean-Fresnel in the early 1820s, the Fresnel lens revolutionized lighthouses throughout the world. Its deceptively simple design meant that light could travel much farther from a lighthouse beam than with a conventional lens. Six types of Fresnel lenses were manufactured for lighthouses in the 1800s, sixth-order, fifth-order, fourth-order, third-order, second-order, and first-order, each one improving upon the other in terms of beam power and range.

In short, a Fresnel lens is much thinner than a conventional lens, using prisms to refract light to the center of the lens, where it is concentrated into a powerful beam.

The first Bodie Island Lighthouse, completed in 1847, used Argand reflector lamps until 1854, less powerful than a Fresnel lens. In 1854, a fourth-order Fresnel lens was installed, dramatically improving the range of the beam. The second tower, completed in 1859, included a third-order Fresnel lens with a range of 15 miles. The third (and current) Bodie Island Lighthouse, completed in 1872, houses the most powerful first-order Fresnel lens, with a range exceeding 18 miles.

Last updated: August 16, 2017