Technical parameterTolerance Diameter range1-400mm Diameter tolerance+0/-0.05mm Angle tolerance卤2鈥?卤5鈥濃€?/p> Surface Quality40/20 Surface Figure位/10 per @633nm Bevelling0.1-0.5mm MaterialOptical glass or infrared optical material Coating 8-14渭m or 3-5渭m Change of refractive index with wavelength Wavelength (nm)Refractive index (n)WavelengthRefractive index 13573.497540003.4257 1367.33.492642583.4245 1395.13.492945003.4236 1529.53.479550003.4223 1660.63.469655003.4213 1709.23.466460003.4202 1813.23.460865003.4195 1970.23.453770003.4189 2152.63.447675003.4186 Features: Silicon (Si) Windows manufactured from optical grade silicon are popular for the 1.2 - 7碌m spectral region due to their low cost (1/10 of Germanium and ZnSe price) and low density. Due to its low density (half that of Germanium or Zinc Selenide), Silicon windows is ideal for weight sensitive applications, especially those in the 3 - 5碌m region. Density is 2.329 g/cm3 and Knoop Hardness is 1150, making it harder and less brittle than Germanium. Optical grade Silicon is normally specified with a resistivity of 10 to 40 Ohm-cm which is higher than most semiconductor applications. The usual Silicon material, unless otherwise specified is Czochralski (Cz) Grade which has a Si-O absorption band at 9渭m and so not important if the windows are used in the 3 to 5渭m thermal band. Where required Float Zone (FZ) material can be supplied which does not have this absorption. Thin FZ Si windows of 0.5-1mm thickness can be used at 8-12渭m band. Very high resistivity (>1000 Ohm*cm) material can be supplied on special order, particularly for THz applications. We produce hyper- and hemispherical Si lenses with R2-R12.7mm. Silicon is used for windows and lenses in the 2-6碌m range, ideal choice for IR LED lenses. The refractive index is near 3.4 throughout the range. Silicon high thermal conductivity and low weight are attractive features in IR or FTIR applications. Silicon is also used as a high reflectivity mirror substrate for lasers and for IR silicon viewports. Product Pictures:Optical Window suppliers website:http://www.alsfox-optics.com/infrared-optics/optical-window/