A Fresnel lens is a type of compact lens originally designed for use in lighthouses. It consists of a series of concentric rings, which reduce the amount of material needed while maintaining the lens's ability to focus light. This design allows for a thinner and lighter lens compared to traditional curved lenses, making it easier to handle and install. Fresnel lenses are used in various applications beyond lighthouses, including in projectors, camera systems, and solar energy devices. Their unique structure enables them to capture and direct light efficiently, making them valuable in both commercial and scientific fields.