Almost any pair of sunglasses, even those cheap gas-station shades, can make you instantly look cooler. Decidedly uncool are the benefits that single-digit spectacles can’t afford—like cutting down on glare on sunny or snowy days, and preventing UV rays from slowly cooking your eyeballs. Luxottica, the company behind Ray-Ban and its iconic Wayfarers, has a very particular recipe for the sandwiched stack of materials that make up its Sun RX prescription lenses.
Layer 1: Scratch-Resistant Shell
Ray-Ban encases the entire lens in a layer of silicone resin to protect the surface from scratches and nicks. Applied via wet-bath for uniform coverage, the coating hardens under heat and UV light.
Layer 2: Colored Tint
Rather than tinting the lens itself—which could lead to uneven coloration as a result of the prescription-cutting process—Ray- Ban applies color as a separate polycarbonate layer. Dyes mix with the molten raw material prior to molding.
Layer 3: Polarizing Film Light reflecting off flat surfaces such as lakes and roads oscillates horizontally, creating glare in situations where sunglasses matter most. A thin layer of polyvinyl alcohol with a series of microscopic vertical slits stretches across the lens, canceling out (or polarizing) the harsh light.
Layer 4: Prescription Lens A computer-guided diamond cutter contours polycarbonate lenses to ‘script-perfect magnification. The impact-resistant material filters vision-impairing UV light and is roughly half the weight of hardened glass common in other shades.
Layer 5: Anti-Reflective Coating
A dark, shiny surface tends to act like a mirror, especially in bright sun. To combat this effect, invisible layers of silica oxide, titanium oxide, and zirconium oxide bounce light in a different directions, keeping reflections of your face out of sight.
source: popsci.com By Stan Horaczek