A Fresnel Lens was developed by French physicist Augustin-Jean Fresnel for use in lighthouses.
Fresnel lenses consist of a series of concentric grooves etched into plastic. Their thin, lightweight construction, and excellent light gathering ability make them useful in a variety of applications .
A Fresnel lens replaces the curved surface of a conventional optical lens with a series of concentric grooves. These contours act as individual refracting surfaces, bending parallel light rays to a common focal length. As a result, a Fresnel lens, while thin, is capable of focusing light similar to a conventional optical lens but with many advantages.