ballistic performance of polycarbonates. In the early 1970s, Wigglesworth investigated the ballistic resistance of 3 mm. and 2 mm. thicknesses of allyl resin and tempered glass as a function of the diameter of a small steel ball, impact velocity, and curvature of the lens. In 1996, Belkin described new ballistic eyewear that also provided improved protection from injuries caused by laser light reaching the eyes. Research into improved protection of the eyes from ballistic threats has continued. For example, Kelly presented work investigating layered materials to provide protection from 9 mm automatic gunfire, a much greater level of ballistic protection than previously available. While they demonstrated a successful concept, they recognized that advances in manufacturability were still needed for such protective eyewear to be affordable and plentiful. In 2006 Hartley et al. were awarded a US Patent for Eyewear for ballistic and light protection. The invention was not for new protective materials but for a system that would allow the easier interchange of lenses between various types of protective devices, such as glasses, goggles and face shields. References External links Examples of gas mask glasses and other military glasses from WWI and WWII A brief story of Eduoard Benedictus inventing laminated glass. La Piana FG, Ward TP. The development of eye armor for the American infantryman. Ophthalmology Clinics of North America. 1999;12(3):421–434 Safety clothing Eyewear Ballistics