Best Price High Transmission AR Coated Optical Ge/Ge Window for Infrared Imaging

Germanium windows are optical windows that are opaque to ultraviolet and visible light, but have a wide range of transmission in the infrared. It has minimal chromatic aberration due to low dispersion and we recommend anti-reflective coating due to its high refractive index (4.0 from 2 – 14μm).

Germanium (Ge) is a heavy and hard substance with a Knoop hardness of 780, almost twice that of MgF. It is often a good choice for applications where rugged optics are critical. Its density is 5.33 g/cm3. Its transfer characteristics do drop dramatically with increasing temperature, a property known as thermal runaway, and we don't recommend it for applications where temperatures typically rise above 100C.

It is well suited for IR laser applications, especially where rugged optics are required. It can also be used as a longpass filter, transmitting only wavelengths greater than 2 µm. Germanium is non-reactive to air, water, alkalis, and many acids, and is highly scratch-resistant.