Silicon is a semiconductor material commonly used in infrared optical systems op- erating in the near-IR and MW spectral band. Silicon has the lowest density among common infrared materials, making it ideal for systems with weight constraint.
Silicon (Si) Windows manufactured from optical grade silicon are popular for the 1.2 - 7µm spectral region due to their low cost and low density. Due to its low density (half that of germanium or zinc selenide), silicon is ideal for weight sensitive applica- tions, especially those in the 3 - 5µm region. Density is 2.329 g/cm3 and Knoop Hard- ness is 1150, making it harder and less brittle than germanium.
