BK7 B270 Optical Glass Window An Optical Window is an optically flat. These regular windows are applied to isolate different physical environments while allowing light pass. When selecting windows,please consider materials, transmission, scattering, parallelism and resistance to certain environment. It can be widely used on laser technology, IR detector and imaging technology etc. Worldhawk offers standard and high precision optical glass windows in round ,rectangular, wedge windows and custom shape and size with different optical glasses,Fused Silica, Sapphire, ZnSe, Zns and IR crystal. The high precision parallelism of 10 arc seconds, surface quality of 10/5 and flatness of �»/20. Single layer or multi-layer anti-reflection coatings are available.