The Office of Naval Research funded the development of a simple array of six lights outfitted with Fresnel lenses mounted on the stern of a ship, called a Tactical Vectoring Equipment (TVE) display.

The most important thing to know about Fresnel lenses, before casually attempting to drop them into conversation, has to do with phonetics: "Fresnel" is pronounced "Fruh-NEL." If the silent "S" makes ...