Before GPS, radar, and modern digital navigation, sailors depended on a powerful beam of light.

But a lighthouse isn't simply a giant flashlight.

Its optics, rotating mechanisms, lens design, elevation, visibility, and flashing pattern are all carefully engineered to help ships identify their position and avoid dangerous waters.

In Engineering Insights S2 E90, we explore the engineering behind lighthouse optical and navigation systems.

We begin with the light source.

Early lighthouses used candles, oil lamps, and later more powerful lamps. Modern systems can use high-intensity electric lights and specialized optics to project light across enormous distances.

The most fascinating component is often the Fresnel lens.

Instead of using a massive solid lens, engineers divided  ...