Nanometer-scale surface relief structures that can be designed to provide ultrahigh broadband antireflection performance, with structures etched or replicated directly into the surface of the bulk material, have been developed by TelAztec. They eliminate the need for thin-film antireflection coatings and offer durability in harsh environments. Laser damage threshold testing was conducted on the microstructures and fabricated in Schott Borofloat glass windows 80 mm in diameter and 2.75 mm thick. One window was antireflection-treated on both surfaces, and the other was untreated. The test was performed at 1064 nm with a 20-ns pulse length. The treated glass had a laser damage threshold of 56.8 J/cm2, whereas the untreated glass registered 38.3 J/cm2.