| Optics. a large lens with a surface of concentric grooves of prismatic profile, used in automobile headlights, searchlights, spotlights, etc. |
Fres·nel lens  (frə-něl')   (click for larger image in new window) n. A thin optical lens consisting of concentric rings of segmental lenses and having a short focal length, used primarily in spotlights, overhead projectors, and the headlights of motor vehicles. [After Augustin Jean Fresnel.] |
| Fresnel lens (frə-něl') Pronunciation Key
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. |
