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