Edmund Optics Inc. 25mm Diameter Germanium Window, Uncoated NT68-737

Uncoated or with AR Coatings Designed for 3-12µm or 8-12µm Minimal Chromatic Aberration Due to Low Dispersion Ideal for Infrared Applications Requiring Rugged Optics TECHSPEC® Germanium (Ge) Windows are available off-the-shelf with two anti-reflection coating options: 3 - 12µm for mid-infrared or broadband multi-spectral applications, or 8 - 12µm for thermal imaging applications. Due to its high index of refraction (around 4.0 from 2 - 14µm), an anti-reflection coating is recommended on these germanium windows for sufficient transmission in the region of interest. Germanium is subject to thermal runaway, meaning that the transmission decreases as temperature increases. As such, these germanium windows should be used at temperatures below 100°C. Germaniums high density (5.33 g/cm3) should be considered when designing for weight-sensitive systems. The Knoop Hardness of germanium (780) is approximately twice that of magnesium fluoride, making it ideal for infrared applications requiring rugged optics.