Lighthouse In Waves

Fresnel lenses were ranked by Order, with a first order lens being the largest, most powerful and expensive; and a sixth order lens being the smallest. The order is based on the focal length of the lens. A first order lens has the longest focal length, with the sixth being the shortest. Coastal lighthouses generally use first, second or third order lenses, while harbor lights and beacons use fourth, fifth or sixth order lenses.
Some lighthouses, such as those at Cape Race, Newfoundland, and Makapuu Point, Hawaii, used a more powerful hyperradiant Fresnel lens manufactured by the firm of Chance Brothers.
In recent times, many Fresnel lenses have been replaced by rotating aerodrome beacons which require less maintenance. In modern automated lighthouses, this system of rotating lenses is often replaced by a high intensity light that emits brief omnidirectional flashes (concentrating the light in time rather than direction). These lights are similar to obstruction lights used to warn aircraft of tall structures. Recent innovations are "Vega Lights", and initial experiments with LED panels.