Old light technologies: lenses, glasses, telescopes, prisms, Fresnel lenses for lighthouses, ... laser may be too recent to be considered as "old". Despite be

Old light technologies: lenses, glasses, telescopes, prisms, Fresnel lenses for lighthouses, ... laser may be too recent to be considered as "old". Despite being worked on for centuries, optics are still a super active field for fundamental research, R&D, and new products. LEDs are incredible for example. Extraordinary efficiency.