Windows
| Materials | Illustration | Property and Application | |
| Windows | BK7, Germanium, Zinc Selenide, Barium Fluoride, Calcium Fluoride, Silicon,Fused Silica |  |
Windows are used to isolate different physical environments while allowing light to pass. When selecting windows you should consider materials, transmission, scattering, wavefront distortion, parallelism and resistance to certain environment. A window is parallel usually with anti reflection coating |