The Fresnel Lens

• In 1822 the Fresnel lens was invented.

• An unlimited number of flashing combinations, could be produced.

• Ships found the lights to be brighter and they could see the lights at greater distances

• The Fresnel lens is made of 100’s of pieces of specially cut glass.

• It surrounds the lamp bulb, which concentrates the light downward.

Two types of lenses

Fixed Lens• Shows a steady light

all around the horizon

Revolving Lens• Produces a flash or

characteristic.• The number of flashes

per minute depends on the number of flash panels and the speed at which the optic (lens) revolves.

• Because of the special design, and because it is made of glass, the lens intensifies the glow from the lamp.

• The lens takes the rays of light and bends them into a single beam of light, which shines out in a specific direction.

Sites Noted

http://www.outer-banks.com/lighthouses.asp

http://www.uscg.mil/hq/g-cp/history/weblighthouses/lighthouse_curriculum.html