On the upper were two head-lights with a ship's anchor light (Fresnel lens) between them.
|Fresnel lens |
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.