Bull’s Eye Fresnel Lens
The Fresnel Lens revolutionized lighthouse lighting when it was invented in 1822 by Augustin Jean Fresnel in France. Fresnel lenses are shaped with concentric rings of prisms around a central lens. The light source, a lamp or bulb, is behind the central lens. The scattered light that shines out from the lamp is directed by the concentric rings of prisms to form a series of parallel beams so close together they appear as one tight beam. The Fresnal Lens could focus 83% of the light from just one lamp to the distant horizon. In the case of the Port Burwell Lighthouse, its light could be seen 40 km. away.
Lighthouses were a crucial navigational measure on the Great Lakes, but more so in Lake Erie, as the risk of grounding and wrecking was very high due to the shallow waters. The rhythmic flashing light of a lighthouse would warn sailors of dangers and guide them to safety, either away from sandy shoals or toward a harbour. The Port Burwell harbour was one of the best natural harbours on Lake Erie and was the hub of shipping and fishing since the early 1800’s. Later years saw the area fade to become a quiet fishing village and tourist area.
The importance of the Fresnel lenses has not waned as it is still used today, often made of plastic, in the production of automobile headlights, traffic signals and projectors, as well as cameras, magnifying equipment, and solar collectors.
The many Fresnel lenses at the Port Burwell Marine Museum are beautiful examples of an old technology that allowed people to explore and travel throughout Canada’s coastlines and inland lake system.
· Object ID: 988.17.02
· Object Name: Bull’s Eye Fresnel Lens
· Dimensions: 103 cm H x 97 cm W
Jennifer Beauchamp, Curator, Port Burwell Marine Museum and Historic Lighthouse