A lens technology that cuts glare created when light reflects off materials like plastic and glass. In 1929, the founder of Polaroid, Edwin Land, wanted to figure out how to cut glare in car windshields, so he built a huge filter: a layer of stretched-out polyvinyl alcohol and iodine crystals whose pattern of parallel lines blocked glare-producing polarized light waves while allowing other light waves to pass through. This layer was sandwiched between layers of tint, UV filters, and antiscratch treatment. The company added polarization to the sights for American tank gunners in World War II, fashion designers started using it in sunglasses in the fifties, and Nascar drivers like Richard Petty popularized it in the seventies. In the eighties, companies like Costa and Smith began selling polarized fishing sunglasses that allowed anglers to see beneath the surface of the water, and the concept spread to other sports. Today it’s difficult to find a pair of sporty shades that aren’t polarized.