fresnel lens

noun

1. Optics. a large lens with a surface of concentric grooves of prismatic profile, used in automobile headlights, searchlights, spotlights, etc.

noun

1. a lens consisting of a number of smaller lenses arranged to give a flat surface of short focal length

1. A thin optical lens consisting of concentric rings of segmental lenses and having a short focal length. Placing a light source at the focal point of the lens gives rise to a strong beam of nearly parallel rays. Fresnel lenses are used primarily in spotlights, lighthouses, and the headlights of motor vehicles.