Lens Technology

The Fresnel Lens was a significant technological development for light houses. It captures and projects further, as parallel beams, significantly more light from a light source than conventional convex glass lens by using arrays of specially ground and angled glass sections. Other scientist proposed the possibility of parallel light beans, but Augustin-Jean Fresnel, a french engineer and physicist whose work in light was based in the wave theory, developed the first operational lens in the early 1820s, a few years prior to his death. Further development of the original models led to Fresnel lens of different sizes in the second half of the 19th century. The largest were used along ocean shorelines where distance was paramount. The principle behind the Fresnel Lens was extended to other forms of lighting, e.g., theatrical lighting. The Fresnel Lens in the photo, which appears to be one of the largest models (about 12 ft high and capable of throwing a beam of light 20 miles) is located in the Lighthouse and Museum on the Pensacola Naval Air Station (home of the Navy Blue Angles). Today, it is very unusual for find a lighthouse with its original glass Fresnel Lens. Those that remain are likely to have acrylic replica of the original glass.