Optical glass 7-12μm IR2 Ge Plano-Convex (PCX) Lenses

Germanium (Ge) Plano-Convex Lenses are available with a broadband AR coating for the 7 µm to 12 μm spectral range deposited on both surfaces. This coating greatly reduces the high surface reflectivity of the substrate, yielding an average transmission in excess of 94% over the entire AR coating range. See the Graphs tab for detailed information.

Plano-convex lenses have a positive focal length and approachest fobrm for infinite and finite conjugate applications. These lenses focus a collimated beam to the back focus and collimate light from a point source. They are designed with minimal spherical aberration and have a focal length given by:

f = R/(n-1),

where R is the radius of curvature of the convex portion of the lens and n is the index of refraction. To minimize the introduction of spherical aberration, a collimated light source should be incident on the curved surface of the lens when being focused and a point light source should be incident on the planar surface when being collimated.

Due to its broad transmission range (2 - 16 µm) and opacity in the visible portion of the spectrum, germanium is well suited for IR laser applications. It is also inert to air, water, alkalis, and acids (except nitric acid). Germanium's transmission properties are highly temperature sensitive; in fact, the absorption becomes so large that germanium is nearly opaque at 100 °C and completely non-transmissive at 200 °C. For other MIR lenses and spherical singlets, please refer to the Selection Guide below.

When handling optics, one should always wear gloves. This is especially true when working with germanium, as dust from the material is hazardous. For your safety, please follow all proper precautions, including wearing gloves when handling these lenses and thoroughly washing your hands afterward.